The Anterior Cruciate Ligament: Reconstruction and Basic Science1

About this Book Why this Book Is Needed The anterior cruciate ligament (ACL) is one of the most written about topics in Orthopaedics, such that it has become very difficult for most Orthopaedists to stay current through regular casual reading of the literature. Yet until now there has not been a comprehensive ACL text. This book fills that gap. We have attempted to present the essence of the world’s accumulated clinically relevant ACL-related knowledge in 81 concise chapters.

in this text, along with the many videos, provide a more in-depth alternative. Through partnership with the leading sports medicine companies, new devices will be introduced on the website along with expert orthopaedic evaluations—“peer reviewed marketing.”

The Technique of ACL Reconstruction The best techniques for each component of ACL reconstruction: harvest, fixation, tunnels, notchplasty, and so forth, are collected and presented. This information leads directly to good outcomes.

About the Associate Editors and Contributors

Choices

The associate editors listed on the cover and the other contributors are a “dream team” of leading ACL surgeons and scientists from around the world who were chosen based on their accomplishments and research on the specific topic of their chapter. Other distinguished surgeons are being continually added as special contributors of new “hot topics” for the ACL website.

After technique, ACL surgery is all about choices: interference versus cortical fixation, bone–patella tendon–bone versus hamstring, auto versus allograft, accelerated versus protected rehab, anterior versus posterior hamstring harvest, metal versus bio versus osteoconductive, single versus double bundle, and so on. Information on both sides of each argument is presented to allow the surgeon to make each choice a well-informed one.

Fixation Devices and Troubleshooting Each of the leading ACL reconstruction fixation devices has its own chapter written by its creator or one of its most skilled users. Each such chapter presents scientific rationale, technique, results, and, most importantly, a troubleshooting section. Every surgeon encounters technical problems during cases, but we know of no other source for the practicing surgeon to find the best way to get out of them. Most device information comes to surgeons from company representatives who do provide a useful service; but the chapters

Related Topics The expert treatment of related pathology— cartilage and ligamentous—is essential for the ACL surgeon, and is presented here. There are also 10 chapters on different types of complications, much of it probably unfamiliar to many. There is original research on the incidence of ACL tears, economics, and stability results. New horizons, including four double bundle techniques, navigation, and tissue engineering are also presented, along with biomechanical information and much more. vii

About this Book

The DVD Dozens of surgical technique videos of the component techniques that make up ACL reconstruction, and a few additional topics, comprise the included DVD. Some videos were created especially for this DVD, others represent classics from the AAOS and elsewhere. All are the best we know of on the given topic and form the only such large collection of ACL videos.

The Website The dedicated website includes an e edition of the book. At this writing there are 10 additional chapters not included in the print version on new “hot topics,” such as quadriceps tendon ACL reconstruction results, and more will be added as new advances or controversies emerge. There are also product introductions in partnership with industry, useful links, course offerings, and much more. The website also includes the “Ask the Experts” and “ACL Database” features described below.

Ask the Experts The contributors to this book have all agreed to field questions from Orthopaedic Surgeons with website passwords on their particular topics, or others. These

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e-mailed queries are directed to a central question center, distributed to the appropriate surgeon, and then answered confidentially to the surgeon who posed the question. The idea is to assist surgeons everywhere to better treat their patients by getting help from the best when they need it.

Staying Current: The ACL Database The book’s short gestation period has ensured that each chapter is up-to-date at publication. However, through the book’s website, significant new ACL-related knowledge is being added each quarter to keep it that way. This is how it works: Beginning in January 2007, every month the 50 or so new ACL-related article references published in the world’s peer reviewed literature have been appended to the bibliography for the most relevant chapter(s) or sections of the text to which they relate. Presentations and even posters from the major sports medicine meetings are similarly categorized each month. Thus, the ACL database presents a continually updated compendium of essentially all the world’s new ACL-related knowledge as it is being created, organized by topic. This is an ideal research tool for any ACL-related topic about which you need to know.

Acknowledgments The special contributors listed on the cover of the book have been involved in this project from the beginning and have supported its development with their time and energy simply because they believed in the worthwhile nature of the project. There are none brighter or more dedicated. I am grateful to them and to all the other esteemed contributing authors: the “dream team” of ACL scientists and surgeons described on the preceding page. I was confident that they would produce the outstanding works of scholarship that they have, but I was continually surprised at how easy to work with these illustrious scientists and surgeons all were and how they respected the time deadlines and constraints of space and organizational structure of the project. This clearly comes

from being passionate about their ideas and their work and is reflected in the high quality of the chapters. I would also like to especially thank one of those contributors, Bert Zarins, for all he taught me about both sports medicine and life as my fellowship mentor many years ago. Kim Murphy and all of the people at Elsevier have been a great pleasure to deal with. She showed enthusiasm and creativity for the project from the beginning and continues to do so. They have also worked diligently to help avoid delays so that the book will be up to date at its publication. Finally, the staff at our clinic and my family have all been wonderful about the time diverted from them to this book.

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List of Contributors Keiichi Akita, MD, PhD Unit of Clinical Anatomy, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Arturo Almazan, MD Orthopedic Sports Medicine and Arthroscopy Department, National Institute of Rehabilitation; Associate Professor, Sports Medicine Residency Program, National Autonomous University of Mexico, Mexico City, Mexico Andrew A. Amis, PhD, DSc(Eng), FIMechE Professor, Departments of Mechanical Engineering and Musculoskeletal Surgery, Imperial College London, London, England Allen F. Anderson, MD Director, Lipscomb Clinic Research and Education Foundation, Tennessee Orthopedic Alliance, Nashville, Tennessee Christian N. Anderson, MD Resident, Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee John C. Anderson, MD Pacific Orthopaedics and Sports Medicine; Medical Staff, Portland Adventist Medical Center Portland, Oregon

F. Alan Barber, MD, FACS Fellowship Director, Plano Orthopedic and Sports Medicine Center, Plano, Texas Gene R. Barrett, MD Codirector of Knee Service, Mississippi Sports Medicine and Orthopaedic Center, Jackson, Mississippi Guy Bellier, MD Cabinet Goethe, Institut de l'Appareil Locomoteur Nollet, Paris, France Manfred Bernard, MD Priv.-Doz., Klinik Sanssouci, Berlin, Germany Bruce D. Beynnon, PhD Associate Professor, McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont Robert H. Brophy, MD Fellow, Shoulder/Sports Medicine, Hospital for Special Surgery, New York, New York Charles H. Brown, Jr., MD Medical Director, Abu Dhabi Knee and Sports Injury Centre, Abu Dhabi, United Arab Emirates xi

List of Contributors Taylor D. Brown, MD Bone and Joint Center of Houston, Houston, Texas Anthony Buoncristiani, MD Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania David Caborn, MD Department of Orthopaedic Surgery, University of Louisville, Louisville, Kentucky Guglielmo Cerullo, MD Clinica Valle Giulia, Roma, Italy Neal C. Chen, MD Clinical Fellow, Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, New York Pascal Christel, MD, PhD Professor of Orthopaedic Surgery, Institut de l'Appareil Locomoteur Nollet, Paris, France Vassilis Chouliaras, MD Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece Massimo Cipolla, MD Clinica Valle Giulia, Roma, Italy Philippe Colombet, MD Clinique du Sport de Bordeaux, Mérignac, France Nader Darwich, MD Deputy Medical Director, Abu Dhabi Knee and Sports Injury Centre, Abu Dhabi, United Arab Emirates Laura Deriu, MD Department of Orthopaedics, Catholic University, Rome, Italy Patrick Djian, MD Cabinet Goethe, Institut de l'Appareil Locomoteur Nollet, Paris, France Apostolos P. Dimitroulias, MD Orthopaedic Surgeon, University Hospital of Larissa, Larissa, Greece xii

Lars Ejerhed, MD, PhD Department of Orthopaedics, Northern Älvsborg County Hospital, Uddevalla Hospital, Trollhättan Uddevalla, Sweden Carlo Fabbriciani, MD Professor and Chairman of Orthopaedics and Traumatology, Department of Orthopaedics, Catholic University, Rome, Italy Julian A. Feller, FRACS Associate Professor, Musculoskeletal Research Centre, La Trobe University; Orthopaedic Surgeon, La Trobe University Medical Centre, Melbourne, Victoria, Australia Mario Ferretti, MD Research Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Jean Pierre Franceschi, MD Hôpital de la Conception, Marseille, France Ramces Francisco, MD Orthopaedic Surgeon/Affiliate, Orthopaedic Arthroscopic Surgery International, Clinica Zucchi, Milan, Italy Vittorio Franco, MD Clinica Valle Giulia, Roma, Italy Stuart E. Fromm, MD Black Hills Orthopaedic and Spine Center, Rapid City, South Dakota Freddie H. Fu, MD, DSc (Hon), DPs (Hon) David Silver Professor and Chairman, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania John P. Fulkerson, MD Orthopedic Associates of Hartford, P.C.; Clinical Professor and Sports Medicine Fellowship Director, Department of Orthopedic Surgery, University of Connecticut, Farmington, Connecticut William E. Garrett, Jr., MD, PhD Duke Sports Medicine Center, Durham, North Carolina

List of Contributors Anastasios Georgoulis, MD Professor of Orthopaedic Surgery; Chief, Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece George Giakas, BSc, PhD Department of Sports Science, University of Thessaly, Karyes, Trikala, Greece Enrico Giannì, MD Clinica Valle Giulia, Roma, Italy Thomas J. Gill, MD Assistant Professor, Department of Orthopedic Surgery, Harvard Medical School, Boston, Massachusetts Alberto Gobbi, MD Director, Orthopaedic Arthroscopic Surgery International, Clinica Zucchi, Milan, Italy Steven Gorin, DO Institute of Sports Medicine and Orthopaedics, P.A. Aventura, Florida Tinker Gray, MA, ELS Research Director, Shelbourne Knee Center at Methodist Hospital, Indianapolis, Indiana Letha Y. Griffin, MD, PhD Peachtree Orthopaedic Clinic, Atlanta, Georgia

Stephen M. Howell, MD Professor, Department of Mechanical Engineering; Member of Biomedical Graduate Group, University of California at Davis, Sacramento, California Mark R. Hutchinson, MD Professor of Orthopaedics and Sports Medicine, University of Illinois at Chicago, Chicago, Illinois R.P.A. Janssen, MD Orthopaedic Surgeon, Department of Orthopaedic Surgery and Traumatology, Máxima Medical Center, Veldhoven, Netherlands Timo Järvelä, MD, PhD Department of Orthopaedics and Traumatology, Tampere City Hospital; Tampere University, Tampere, Finland; Department of Orthopaedics Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Markku Järvinen, MD, PhD Tampere University; Department of Trauma, Musculoskeletal Surgery, and Rehabilitation, Tampere University Hospital, Tampere, Finland Don Johnson, MD, FRCS Director, Sports Medicine Clinic, Carleton University, Ottawa, Ontario, Canada

David R. Guelich, MD Chicago Orthopaedics and Sports Medicine, Chicago, Illinois

Brian T. Joyce, BA Research Coordinator, Illinois Sports Medicine and Orthopaedic Centers, Glenview, Illinois

Yung Han, MD Resident, McGill University Orthopaedic Surgery Residency Program, Montreal, Canada

Auvo Kaikkonen, MD, PhD Inion Oy; Tampere University, Tampere, Finland

Michael E. Hantes, MD Consultant Orthopaedic Surgeon, University Hospital of Larisa, Larisa, Greece

Anastassios Karistinos, MD Assistant Professor, Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, Texas

Aaron Hecker, MA Bioskills Laboratory Manager, Smith and Nephew, Mansfield, Massachusetts

Jüri Kartus, MD, PhD Department of Orthopaedics, Norra Älvsborg/Uddevalla Hospital, Trollhättan, Sweden xiii

List of Contributors John F. Keating, BA, MB, BCh, BAO, MPhil, FRCSI, FRCSEd Consultant Orthopaedic Surgeon, Department of Trauma and Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom James Kercher, MD Emory School of Medicine, Emory University, Atlanta, Georgia Petteri Kousa, MD, PhD Department of Orthopaedics; Department of Surgery, University of Tampere, Tampere University Hospital, Tampere, Finland; Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center; Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont Jason Koh, MD Northwestern Medical Faculty Foundation, Chicago, Illinois Michael Kuhn, MD Clinical Instructor, Surgery, Uniformed Services University, Bethesda, Maryland; Fellow, Department of Orthopaedic Surgery and Sports Medicine, New England Baptist Hospital, Boston, Massachusetts Bert R. Mandelbaum, MD Santa Monica and Orthopaedic and Sports Medicine Foundation, Santa Monica, California Robert G. Marx, MD, MSc, FRCSC Associate Professor of Orthopedic Surgery and Public Health, Weill Medical College of Cornell University; Attending Orthopedic Surgeon; Director, Foster Center for Clinical Outcome Research, Hospital for Special Surgery, New York, New York Brian P. McKeon, MD Assistant Clinical Professor of Orthopedics, Tufts University; Head Team Physician, Boston Celtics, Boston Sports and Shoulder Center, Chestnut Hill, Massachusetts xiv

Giuseppe Milano, MD Associate Professor, Department of Orthopedics, Catholic University, Rome, Italy Mark D. Miller, MD Professor, Department of Orthopaedic Surgery, Director of Sports Medicine, University of Virginia; Team Physician, James Madison University, Charlottesville, Virginia Kai Mithoefer, MD Clinical Instructor in Orthopedic Surgery, Harvard Medical School; Harvard Vanguard Orthopedics and Sports Medicine, Brigham and Women's Hospital, Boston, Massachusetts Tomoyuki Mochizuki, MD, PhD Section of Orthopedic Surgery, Division of Cartilege Regeneration, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Anna-Stina Moisala, MD Tampere University, Tampere, Finland Craig D. Morgan, MD The Morgan-Kalman Clinic, Wilmington, Delaware Constantina Moraiti, MD Department of Orthopaedic Surgery, Orthopaedic Sports Medicine Center of Ioannina, University of Ioannina, Ioannina, Greece Takeshi Muneta, MD, PhD Section of Orthopedic Surgery, Division of Cartilege Regeneration, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Brian J. Murphy, MD Freeworld Imaging, Miami, Florida Janne T. Nurmi, DVM, PhD Inion Oy; Faculty of Veterinary Medicine, Department of Clinical Veterinary Sciences, University of Helsinki, Tampere, Finland

List of Contributors Nicholas E. Ohly, MBBS, MRCSEd Specialist Registrar, Department of Trauma and Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom Antti Paakkala, MD, PhD Department of Radiology, Tampere University Hospital, Tampere, Finland Lonnie E. Paulos, MD Professor, Orthopedic Surgery, Baylor College of Medicine; Codirector, The Roger Clemens Institute for Sports Medicine and Human Performance, Houston, Texas Hans H. Paessler, MD ATOS Clinic, Center of Knee Surgery, Foot Surgery and Sports Trauma, Heidelberg, Germany Hemant G. Pandit, FRCS (Orth) North Hampshire Hospital, Nuffield Orthopaedic Centre, Oxford, United Kingdom Michael J. Patzakis, MD Professor and Chairman, Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California; LACþUSC Medical Center, Los Angeles, California Chadwick C. Prodromos, MD President, Illinois Sports Medicine and Orthopaedic Centers; Assistant Professor, Orthopaedic Surgery, Section of Sports Medicine, Rush University Medical Center, Chicago, Illinois Giancarlo Puddu, MD Clinica Valle Giulia, Roma, Italy

New England Baptist Hospital, Boston, Massachusetts Andrew Riff, BS Medical Student, Georgetown University School of Medicine, Washington, DC Stavros Ristanis, MD, PhD Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece James Robinson, MD Imperial College of Science, Technology and Medicine, London, United Kingdom Julie Rogowski, BS Professional Education Coordinator, Illinois Sports Medicine and Orthopaedic Centers, Glenview, Illinois Abdou Sbihi, MD Hôpital de la Conception, Marseille, France Sven Ulrich Scheffler, MD Sports Medicine and Arthroscopy Service, Department of Orthopaedics and Traumatology, Center for Musculoskeletal Surgery, Charité, Campus Mitte, University Medicine Berlin, Berlin, Germany K. Donald Shelbourne, MD Shelbourne Knee Center at Methodist Hospital; Associate Professor, Department of Orthopaedics, Indiana University School of Medicine, Indianapolis, Indiana Kelvin Shi, MS Statistician, Forest Labs, Inc., New York, New York Konsei Shino, MD, PhD Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan

Paul Re, MD Director, Sports Medicine Emerson Hospital Orthopaedic Affiliates, Concord, Massachusetts

Holly J. Silvers, MPT Director of Research, Santa Monica Orthopaedic and Sports Medicine Research Foundation, Santa Monica, California

John Richmond, MD Chairman, Department of Orthopaedics,

Joseph H. Sklar, MD Assistant Clinical Professor, Tufts University School of Medicine; xv

List of Contributors New England Orthopaedic Surgeons, Springfield, Massachusetts

Center for Musculoskeletal Surgery, Berlin, Germany

James R. Slauterbeck, MD Associate Professor, McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont

Tony Wanich, MD Orthopaedic Resident, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York

James S. Starman, MD Research Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Nicholas Stergiou, PhD HPER Biomechanics Laboratory, University of Nebraska at Omaha, Omaha, Nebraska Neil P. Thomas, BSC, MB, BS, FRCS North Hampshire Hospital, Basingstoke, United Kingdom; Hampshire Clinic, Wessex Knee Unit, Hampshire, United Kingdom Fotios Paul Tjoumakaris, MD Attending Physician, Department of Orthopaedics, Cape Regional Medical Center, Cape May Court House, New Jersey Harukazu Tohyama, MD, PhD Associate Professor, Department of Sports Medicine, Hokkaido University School of Medicine, Sapporo, Japan Elias Tsepis, BSc, PT, MSc, PhD Associate Professor, Physical Therapy, Supreme Technological Institution of Patra at Aigio, Patra, Greece Frank Norman Unterhauser, MD Center for Musculoskeletal Surgery, Clinic for Trauma and Reconstructive Surgery, Charité, Campus Mitte, Berlin, Germany George Vagenas, BSc, PhD National and Kapodistrian University of Athens, Faculty of Physical Education and Sport Science, Illioupolis, Attiki, Greece Michael Wagner, MD Sports Traumatology and Arthroscopy Service, xvi

Russell F. Warren, MD Professor of Orthopaedics, Weill Medical College of Cornell University; Surgeon-in-Chief, Hospital for Special Surgery, New York, New York Kate E. Webster, PhD Research Fellow, Musculoskeletal Research Centre, La Trobe University, Melbourne, Victoria, Australia Andreas Weiler, MD, PhD Head of Sports Traumatology and Arthroscopy Service, Center for Musculoskeletal Surgery, Berlin, Germany Kazunori Yasuda, MD, PhD Professor and Chairman, Department of Sports Medicine and Joint Surgery, Hokkaido University School of Medicine, Sapporo, Japan Bing Yu, PhD Associate Professor, Division of Physical Therapy, Department of Allied Health Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina Charalampos G. Zalavras, MD Associate Professor, Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California; LACþUSC Medical Center, Los Angeles, California Bertram Zarins, MD Augustus Thorndike Clinical Professor of Orthopaedic Surgery, Harvard Medical School; Chief, Sports Medicine Service, Massachusetts General Hospital, Boston, Massachusetts

PART A ANATOMY, PHYSIOLOGY, BIOMECHANICS, EPIDEMIOLOGY

Anatomy and Biomechanics of the Anterior Cruciate Ligament INTRODUCTION Anterior cruciate ligament (ACL) reconstruction is the sixth most common procedure performed in orthopaedics, and it is estimated that between 75,000 and 100,000 ACL repair procedures are performed annually in the United States alone.1,2 The ACL has therefore been intensively studied, and outcomes of ACL surgery have received considerable attention. This has included research on surgical technique factors such as tunnel position, graft choices, and fixation methods, as well as postoperative rehabilitation protocols. Traditional single-bundle ACL reconstruction has focused on reconstruction of one portion of the ACL, the anteromedial (AM) bundle, and although outcomes are generally good, with success rates between 69% and 95%, there remains room for improvement.3,4 A prospective study of a cohort of ACL reconstructed patients 7 years after surgery revealed degenerative radiographic changes in 95% of patients, and only 47% were able to return to their previous activity level following ACL reconstruction.5 However, it should be noted that some studies of long-term follow-up have more encouraging results. Jarvela et al demonstrated tibiofemoral degenerative changes in only 18% of patients at 7 years follow-up post ACL reconstruction with bone–patella–bone grafts.6 In addition, Roe et al reported on a cohort of patients reconstructed with bone–patellar tendon–bone grafts and found an incidence of 45% with degenerative radiographic changes at 7 years follow-up, as well

as an incidence of 14% with degenerative changes in a group with hamstring grafts.7 A thorough review of the anatomy and biomechanics of the normal ACL reveals key points regarding its complex role in stabilization of the knee joint. Improved awareness of the anatomy and biomechanical properties of the normal ACL may lead to improvements in techniques for ACL reconstruction and an associated improvement in outcomes over traditional results. This chapter describes the normal anatomy of the two bundles of the ACL and reviews the biomechanical contributions of each bundle.

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CHAPTER

James S. Starman Mario Ferretti Timo Järvelä Anthony Buoncristiani Freddie H. Fu

ANTERIOR CRUCIATE LIGAMENT ANATOMY Historical Descriptions One of the earliest known descriptions of the human ACL was made around 3000 BC, written on an Egyptian papyrus scroll. During the Roman era, the earliest description of the ligament using its modern name was made by Claudius Galen of Pergamon (199–129 BC), who described the “ligamenta genu cruciate.” In 1543 the first known formal anatomical study of the human ACL was completed by Andreas Vesalius in his book De Humani Corporis Fabrica Libris Septum. Two bundles of the ACL were described for the first time in 1938 by Palmer et al, followed by Abbott et al in 1944 and Girgis et al in 1975.8–10 Each author described an AM bundle and a

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Anterior Cruciate Ligament Injury posterolateral (PL) bundle, named for the relative location of the tibial insertion sites of each bundle. More recently, in 1979 and again in 1991, Norwood et al and Amis et al, respectively, described a third bundle of the ACL anatomy, the intermediate (IM) bundle.11,12 Although it may be said that a two-bundle description of the ACL anatomy is an oversimplification of the complete anatomy, many studies have been based on this functional division, and it has been accepted as a reasonable way to understand the anatomy and biomechanics of the ligament. The IM bundle is most similar to the AM bundle in both anatomical and biomechanical considerations, and for the purposes of this chapter it is therefore considered as part of the AM bundle.

Anatomy of the Anteromedial and Posterolateral Bundles The ACL is a structure composed of numerous fascicles of dense connective tissue that connect the distal femur and the proximal tibia. Histological studies have demonstrated that a septum of vascularized connective tissue is present that separates the AM and PL bundles (Fig. 1-1). In addition, it has been shown that the histological properties of the ligament are variable at different stages in ACL development. At the time of fetal ACL development, the ACL is observed to be hypercellular with circular, oval, and fusiform-shaped cells. Later, in the adult ACL, the histology reveals a relatively hypocellular pattern with predominantly fibroblast cells with spindle-shaped nuclei.13,14 The ligament finds its origin on the medial surface of the lateral femoral condyle (LFC), runs an oblique course

within the knee joint from lateral and posterior to medial and anterior, and inserts into a broad area of the central tibial plateau. The cross-sectional area of the ligament varies significantly throughout its course from approximately 44 mm2 at the midsubstance to more than three times as much at both its origin and insertion.10,15,16 The total length of the ligament is approximately 31 to 38 mm and varies by as much as 10% throughout a normal range of motion.17

Anterior Cruciate Ligament Development ACL formation has been observed in fetal development as early as 8 weeks, corresponding to O'Rahilly stages 20 and 21.18,19 A leading hypothesis holds that the ACL originates as a ventral condensation of the fetal blastoma and gradually migrates posteriorly with the formation of the intercondylar space.20 The menisci are derived from the same blastoma condensation as the ACL, a finding that is consistent with the hypothesis that these structures function in concert.21 Another proposed mechanism of fetal ACL formation is from a confluence between ligamentous collagen fibers and fibers of the periosteum.22 Following the initial formation of the ligament, no major organizational or compositional changes are observed throughout the remainder of fetal development.19 Two distinct bundles of the ACL are present at 16 weeks of gestation (Fig. 1-2). In arthroscopy, the AM and PL bundles can also be appreciated, particularly with the knee held in 90 to 120 degrees of flexion (Fig. 1-3). Finally, cadaveric dissection also reveals two anatomical bundles of the ACL (Fig. 1-4). In summary, there is a considerable amount of interindividual variability with respect to the relative sizes of the AM and PL bundles, as seen in fetal, arthroscopic, and cadaveric studies; however, all individuals with an intact ACL have both bundles of ligament.

Insertion Site Anatomy

FIG. 1-1 Fetal anterior cruciate ligament, sagittal cut. Arrows indicate the septum of vascularized connective tissue dividing the anteromedial (AM) and posterolateral (PL) bundles.

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Anatomical studies have characterized the individual contributions of both the AM and PL bundles to the overall ACL architecture. Odensten and Gillquist described the femoral origin of the ACL as an ovoid area measuring 18 mm in length and 11 mm in width.23 Within this area, the AM bundle occupies a position located on the proximal portion of the medial wall of the LFC, and the PL bundle occupies a more distal position near the anterior articular cartilage surface of the LFC (Fig. 1-5, A). Harner et al studied the digitized origin and insertion of the AM and PL bundles in five cadavers and concluded that each bundle occupies approximately 50% of the total femoral origin, with crosssectional areas of 47  13 mm2 and 49  13 mm2 for AM and PL, respectively.16

Anatomy and Biomechanics of the Anterior Cruciate Ligament

1

FIG. 1-2 16-week fetus demonstrating two bundles of the anterior cruciate ligament with the knee in extension (A, sagittal view with medial femoral condyle removed) and flexion (B, frontal view). AM, Anteromedial; LFC, lateral femoral condyle; PL, posterolateral.

FIG. 1-3 Arthroscopic view of anteromedial (AM) and posterolateral (PL) bundles in 14-year-old female. Left knee, 110 degrees flexion. LFC, Lateral femoral condyle.

On the tibia, the insertions of the AM and PL bundles are located between the medial and lateral tibial spine over a broad area stretching as far posterior as the posterior root of the lateral meniscus. The full ACL insertion has been described as an oval area measuring 11 mm in diameter in the coronal plane and 17 mm in the sagittal plane.10,15,24 Within this area the AM bundle insertion can be found in an anterior

FIG. 1-4 Two distinct bundles of ACL present in cadaveric specimen. Left knee, 90 degrees flexion. AM, Anteromedial; LFC, lateral femoral condyle; PL, posterolateral.

and medial position, whereas the PL bundle insertion is located more posteriorly and laterally (Fig. 1-5, B). Posteriorly, fibers of the PL bundle are in close approximation to the posterior root of the lateral meniscus and, in some individuals, may attach to the meniscus itself (Fig. 1-6). The overall size of the tibial insertion is approximately 120% of the femoral origin; however, as is the case with the femoral origin, the two bundles 5

Anterior Cruciate Ligament Injury

FIG. 1-5 A, Femoral insertion sites of anteromedial (AM) and posterolateral (PL) bundles (right knee, medial femoral condyle removed). B, Tibial insertion sites of AM and PL bundles (right knee tibial plateau, menisci removed). Lat men, Lateral meniscus; MM, medial meniscus.

flexion. The femoral insertion sites are oriented vertically when the knee is in zero degrees, and the two bundles of the ACL are oriented in parallel (Fig. 1-7). As the knee moves into 90 degrees of flexion, the AM bundle insertion site on the femur rotates posteriorly and inferiorly, in contrast to the femoral insertion of the PL bundle, which rotates anteriorly and superiorly. This change in alignment of the insertion sites leads to a horizontal plane of insertions for the AM and PL bundle with the knee in 90 degrees of flexion (Fig. 1-8). The change in insertion site alignment causes the two bundles to twist around each other and become crossed. As the knee is flexed, the PL bundle can be seen anterior to the AM bundle at its femoral insertion (Fig. 1-9).

Tensioning Pattern FIG. 1-6 Posterolateral (PL) bundle tibial insertion is located just anterior to the posterior root of the lateral meniscus (Lat men). Left knee, arthroscopic view.

share approximately equal tibial insertion site areas: the AM bundle occupies 56  21 mm2, and the PL bundle occupies 53  21 mm2.16 The size and length of each bundle is also unique. The AM bundle is approximately 38 mm in length.10,15,17 The PL bundle has been less well studied. Kummer and Yamamoto measured the PL bundle in 50 cadavers and determined an average length of 17.8 mm.25 However, the AM and PL bundles have a similar diameter.

Crossing Pattern Based on their anatomical positions, the AM and PL bundles change alignment as the knee moves from extension to 6

The change in alignment of the AM and PL femoral insertion sites allows the ACL to twist around itself as it is moved through a complete range of motion. Clearly, this crossing pattern, along with the differences in the length of each bundle, has implications for the tensioning pattern of the overall ligament and each individual bundle. In a study by Gabriel et al, forces were measured in each bundle during an anterior load of 134N over several flexion angles, as well as for a combined rotatory load of 10 Nm valgus and 5 Nm internal tibial torque.26 The results showed that the PL bundle is tightest in extension (in situ force of 67  30N) and becomes relaxed as the knee is flexed, whereas the AM bundle is more relaxed in extension, and reaches a maximum tightness as the knee approaches 60 degrees of flexion (in situ forces of 90  17N).12,26 This tensioning pattern also can be observed grossly in cadaveric and arthroscopic views of the bundles (Fig. 1-10). The PL bundle is also observed to tighten during internal and external rotation.

Anatomy and Biomechanics of the Anterior Cruciate Ligament

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FIG. 1-7 Crossing pattern of anteromedial (AM) and posterolateral (PL) bundles. With the knee in extension, the AM and PL bundles are parallel (A, left knee, medial femoral condyle removed) and the insertion sites are oriented vertically (B).

FIG. 1-8 Crossing pattern of anteromedial (AM) and posterolateral (PL) bundles. With the knee in flexion, the AM and PL bundles are crossed (A, left knee, medial femoral condyle removed) and the insertion sites are oriented horizontally (B).

In summary, the ACL consists of two distinct bundles, the AM and PL bundles, and these bundles contribute synergistically to the stability of the knee. The alignment of the insertion sites of AM and PL on the femur allows the ligament to become crossed as the knee is flexed and can be observed as a vertical alignment of the femoral insertion sites during extension and a horizontal alignment of femoral insertion sites during flexion. We will now turn our attention to biomechanics for a review of the role of the ACL and the specific contributions of each bundle.

BIOMECHANICS Historical Studies The field of biomechanics has a long history, with the earliest known considerations dating back to Chinese and Greek literature around 400 to 500 BC. The first modern work in biomechanics was completed during the 1500s to 1700s by well-known figures such as Galileo, DaVinci, Borelli, Hooke, and Newton. Orthopaedic biomechanics was 7

Anterior Cruciate Ligament Injury

FIG. 1-9 Arthroscopic view and computer model of anteromedial (AM) and posterolateral (PL) bundle crossing pattern in extension (top) and flexion (bottom). The PL bundle is obscured in extension but becomes visible in flexion as it moves anteriorly on the femoral side. LFC, Lateral femoral condyle.

FIG. 1-10 Arthroscopic views of an anterior cruciate ligament (ACL)-injured left knee with an intact posterolateral (PL) bundle and torn anteromedial bundle (removed). In extension, the PL bundle is tensioned maximally and appears taut (A), and in 90 degrees flexion, the PL bundle is more relaxed (B).

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Anatomy and Biomechanics of the Anterior Cruciate Ligament initially advanced during the 1940s and 1950s by the work of Eadweard Muybridge, Arthur Steindler, Verne Inman, Henry Lissner, and A. H. Hirsch. Since the 1960s, the information learned from biomechanical studies in orthopedics has been applied to refine clinical treatment approaches.

Anterior-Posterior Translation Control The dynamic nature of the two bundles of the ACL during knee flexion demonstrates the complex role of the ACL in stabilization of the knee joint. However, initial biomechanical studies of the ACL focused mainly on its function of resisting anterior tibial translation.27,28 From this work we know that the in situ forces of the ACL vary considerably during a normal range of motion of the knee joint. With a 110N anterior tibial load applied, the ACL demonstrates high in situ forces between 0 and 30 degrees flexion, with a maximum occurring at 15 degrees. In situ forces are at their lowest point between 60 and 90 degrees, with a minimum occurring at 90 degrees. As mentioned earlier, recent studies have also been completed to evaluate the individual roles of each bundle of the ACL in anterior-posterior translation. These studies have shown that the AM bundle has relatively constant levels of in situ forces during knee flexion, whereas the PL bundle is more variable, with high in situ forces at 0, 15, and 30 degrees of flexion but rapidly decreasing in situ forces beyond this angle.28

Rotational Stability Clinical experience has suggested that biomechanical considerations of anterior-posterior translation alone do not correlate with subjective evaluations of knee stability and that a more complete evaluation of the role of rotational stability is relevant.29 Therefore, in recent years closer attention has been given to the rotational stabilizing function of the ACL.26,30,31 Included in the study by Gabriel et al was an analysis of a combined rotatory load of 10 Nm valgus and 5 Nm internal tibial torque at 15 and 30 degrees flexion. For the PL bundle, in situ forces of 21N were recorded at 15 degrees and 14N at 30 degrees. For the AM bundle, in situ forces were 30N and 35N, respectively. This demonstrates that the both the AM and PL bundles contribute to rotational stability of the knee at these angles. In addition to biomechanical studies, recent studies using in vivo kinematics analysis have assessed rotational stability in the ACL during various functional activities such as walking, running, and cutting.32–34 Andriacchi et al studied the in vivo kinematics of normal and ACL-deficient subjects during four phases of walking and determined that

1

an ACL-deficient knee is positioned differently than a normal knee. During walking, the intact ACL maintains a balance of rotation during the interval of swing phase to heel strike. However, in the ACL-deficient knee, an increased internal rotation occurs between these phases of walking, which is maintained through the stance phase.30 A study of running and cutting in ACL-deficient patients demonstrated normal anterior-posterior stability during running but abnormal rotational movements compared with subjects with an intact ACL.34 Finally, a magnetic resonance imaging (MRI)-based study of the in vivo kinematics of the normal ACL during weight-bearing knee flexion has demonstrated that several components of ACL kinematics change during weightbearing knee flexion. First, as the flexion angle increases, axial rotation (or twist) of the ACL increases as well. At full extension the ACL is internally twisted by approximately 10 degrees; however, this increases to approximately 20 degrees when the knee is moved to 30 degrees flexion, and it increases to approximately 40 degrees with the knee at 60 to 90 degrees flexion. Second, the orientation of the ligament within the joint space changes with the flexion angle. As the knee flexion angle increases, so does the lateral angulation of the ligament. Therefore, the ligament may possess a lateral force component, functioning to constrain internal tibial rotation.32,33 In summary, the ACL provides an important part of rotational stability during both low- and high-demand activities by helping to maintain the normal position of the tibiofemoral contact, a role that is shared by both bundles of the ligament.

Biomechanics Considerations in Anterior Cruciate Ligament Surgery Based on the aforementioned research into the role of rotational stability, work has been completed to assess the ability of different surgical techniques in restoring both anteriorposterior translation of the knee and rotational stability. Yagi et al performed a study comparing a single-bundle reconstruction with the femoral tunnel placed at the 11- or 1-o'clock position with anatomical double-bundle ACL reconstruction and the femoral tunnels placed based on the insertion site anatomy of the transected ACL.35 In this study, the doublebundle ACL reconstruction was better able to resist anterior tibial translation at full extension and 30 degrees flexion, compared with the single-bundle technique. Additionally, when a combined internal tibial and valgus torque was applied at 15 and 30 degrees flexion, the double-bundle ACL reconstruction had a response closer to the intact ACL compared with the single-bundle technique. 9

Anterior Cruciate Ligament Injury Yamamoto et al compared the double-bundle ACL reconstruction with a lateral single-bundle reconstruction, with the femoral tunnel placed approximately at a 10-o'clock position for the right knee.36 The double-bundle anatomical reconstruction better restored the anterior tibial translation at 60 degrees and 90 degrees flexion when compared with the single-bundle technique.36 Finally, Tashman et al performed an in vivo kinematics analysis of normal and single-bundle reconstructed knees.31 Subjects with a normal ACL were compared with a group of single-bundle ACL reconstructed patients to evaluate anterior-posterior translation and knee rotation during downhill jogging. Single-bundle ACL reconstructed patients had fully restored anterior-posterior translation as compared with subjects with a normal ACL but were found to lack normal rotational kinematics.31 Because the singlebundle reconstruction is an approximation of the position of the AM bundle, it can be concluded that part of the rotational stability is derived from the actions of the PL bundle. In summary, Yagi et al and Yamamoto et al have demonstrated that normal anterior-posterior translation may be restored using traditional single-bundle reconstruction techniques. However, it is not possible to restore rotational stability using this approach.35,36 In addition, Tashman et al have shown that single-bundle reconstruction is not capable of restoring normal rotational kinematics.36 Anatomical double-bundle reconstruction, in contrast, offers an opportunity to restore both components of normal knee stability as demonstrated in cadaveric biomechanics studies, and it is possible that this will soon be demonstrated in an in vivo kinematics model as well.35,36

CONCLUSION The anatomy of the ACL shows that the ligament consists of two distinct and functional bundles, the AM and PL bundles. These two bundles have unique points of attachment in the knee, and this leads to their complex spatial relationship throughout knee flexion, as well as their different roles in biomechanics and knee stability. It is important to take the anatomical properties of the ACL into consideration when performing ACL surgery. This may lead to a more accurate restoration of knee kinematics to the native state and improvements in long-term outcomes. However, although the current body of knowledge of the anatomy and biomechanics of the ACL is extensive, it remains incomplete. Future work in areas such as in vivo kinematics will allow for a more complete understanding of rotational stability and knee motion during complex movements.

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References 1. ABOS, Diplomat 2004. www.abos.org 2. Griffin LY, Agel J, Albohm MJ, et al. Non-contact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 2000;8:141–150. 3. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction: a meta-analysis. Arthroscopy 2001;17:248–257. 4. Freedman KB, D'Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 5. Fithian DC, Paxton EW, Stone ML, et al. Prospective trial of a treatment algorithm for the management of the anterior cruciate ligamentinjured knee. Am J Sports Med 2005;33:335–346. 6. Jarvela T, Paakkala T, Kannus P, et al. The incidence of patellofemoral osteoarthritis and associated findings seven years after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18–24. 7. Roe J, Pinczewski LA, Russell VJ, et al. A seven year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction. Am J Sports Med 2005;33:1337–1345. 8. Palmer I. On the injuries to the ligaments of the knee joint. Acta Chir Scand 1938;91:282. 9. Abbott LC, Saunders JB, Bost FC, et al. Injuries to the ligaments of the knee joint. J Bone Joint Surg Am 1944;26A:503–521. 10. Girgis FG, Marshall JL, Al Monajem ARS. The cruciate ligaments of the knee joint. Clinic Orthop 1975;106:216–231. 11. Norwood LA, Cross MJ. Anterior cruciate ligament: functional anatomy of its bundles in rotary instabilities. Am J Sports Med 1979;7:23. 12. Amis AA, Dawkins GPC. Functional anatomy of the anterior cruciate ligament. Fibre bundle actions related to ligament replacement and injuries. J Bone Joint Surg Br 1991;73:260–267. 13. Shino K, Inoue M, Horibe S, et al. Maturation of allografts tendons transplanted into the knee. An arthroscopic and histological study. J Bone Joint Surg Br 1988;70:556–560. 14. Falconiero RP, DiStefano VJ, Cook TM. Revascularization and ligamentization of autogenous anterior cruciate ligament grafts in humans. Arthroscopy 1998;14:197–205. 15. Arnoczsky SP. Anatomy of the anterior cruciate ligament. Clin Orthop 1983;172:19–25. 16. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 17. Fu FH, Bennett CH, Lattermann C, et al. Current trends in anterior cruciate ligament reconstruction. Part 1: biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821–830. 18. O'Rahilly R. The early prenatal development of the human knee joint. J Anat 1951;85:166–170. 19. Gardner E, O'Rahilly R. The early development of the knee joint in staged human embryos. J Anat 1968;102:289–299. 20. Ellison AE, Berg EE. Embryology, anatomy, and function of the anterior cruciate ligament. Orthop Clin North Am 1985;16:3–14. 21. Galleazzi R. Clinical and experimental study of the semilunar cartilage of the knee joint. J Bone Joint Surg 1929;9:515. 22. Behr CT, Potter HG, Paletta GA, Jr. The relationship of the femoral origin of the anterior cruciate ligament and the distal femoral physeal plate in the skeletally immature knee. An anatomic study. Am J Sports Med 2001;29:781–787. 23. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for reconstruction. J Bone Joint Surg Am 1985;67:257–262. 24. Petersen W, Tillmann B. Anatomy and function of the anterior cruciate ligament. Orthopade 2002;31:710–718.

Anatomy and Biomechanics of the Anterior Cruciate Ligament 25. Kummer B, Yamamoto Y. [Funktionelle Anatomie der Kreuzbaender]. Arthroskopie 1988;1:2–10. 26. Gabriel MT, Wong EK, Woo SL, et al. Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads. J Orthop Res 2004;22:85–89. 27. Takai S, Woo SL-Y, Livesay GA, et al. Determination of the in situ loads on the human anterior cruciate ligament. J Orthop Res 1993;11:686–695. 28. Sakane M, Fox RJ, Woo SL-Y, et al. In situ forces in the anterior cruciate ligament and its bundles in response to anterior tibial loads. J Orthop Res 1997;15:285–293. 29. Kocher MS, Steadman JR, Briggs KK, et al. Relationships between objective assessment of ligament stability and subjective assessment of symptoms and function after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:629–634. 30. Andriacchi TP, Dyrby CO. Interactions between kinematics and loading during walking for the normal and ACL deficient knee. J Biomech 2005;38:293–298.

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31. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 32. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 33. Li G, DeFrate LE, Sun H, et al. In vivo elongation of the anterior cruciate ligament and posterior cruciate ligament during knee flexion. Am J Sports Med 2004;32:1415–1420. 34. Waite JC, Beard DJ, Dodd CA, et al. In vivo kinematics of the ACLdeficient limb during running and cutting. Knee Surg Sports Traumatol Arthrosc 2005;13:377–384. 35. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 36. Yamamoto Y, Hsu Y, Woo SL, et al. Knee stability and graft function after anterior cruciate ligament reconstruction: a comparison of a lateral and an anatomical femoral tunnel placement. Am J Sports Med 2004;32:1825–1832.

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2

CHAPTER

William E. Garrett, Jr. Bing Yu

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Mechanisms of Noncontact Anterior Cruciate Ligament Injuries As in the prevention of other injuries in sports, understanding injury mechanisms is a key component of preventing noncontact anterior cruciate ligament (ACL) injuries.1 The research effort to determine risk factors of sustaining noncontact ACL injuries is increasing as the concerns of increased incidents and cost for treatment, as well as serious consequences of noncontact ACL injuries, are growing. Prospective cohort studies are commonly used in epidemiological research designs for determining risk factors of injuries and diseases2 and are being used to determine risk factors of sustaining noncontact ACL injuries.3 The results of epidemiological studies with cohort designs, however, are descriptive in nature and lack cause-and-effect relationship between identified risk factors and the injury.2 Without a good understanding of the injury mechanisms, the risk factors of sustaining noncontact ACL injuries identified from epidemiological studies could be misinterpreted and could lead to the selection of nonoptimal injury prevention programs. Injuries of the ACL frequently occur in athletic movements such as stopping or quickly changing directions. These kinds of movements often are awkward and off-balance maneuvers. Video analysis often shows a hard landing with the knee near full extension in these movements as the athlete experienced a sensation of the knee collapsing into a valgus position. The quadriceps muscles are likely to be the major source of the anterior shear force that causes the rupture of the ACL in these movements. However, we have not been accustomed to considering the fact that our own muscles can create injuries. Although a

valgus moment applied to the knee can create enough deformation to cause an injury of the ACL, few noncontact ACL injuries involve serious injuries to the medial collateral ligament (MCL) that would occur if the knee sustained sufficient valgus moment loading to injure the ACL. This chapter will examine biomechanical studies relating to ACL injury and explore strains induced by the quadriceps muscles near full knee extension and by valgus moment loading. Mechanically, ACL injury occurs when an excessive tension force is applied on the ACL. A noncontact ACL injury occurs when a person self-generates great forces or moments at the knee that applied excessive loading on the ACL. An understanding of the mechanisms of ACL loading during active human movements, therefore, is crucial for understanding the mechanisms of noncontact ACL injuries and risk factors of sustaining noncontact ACL injuries. Berns et al4 investigated the effects of combined knee loading on ACL strain on 13 cadaver knees. The strain of the anteromedial (AM) bundle of the ACL was recorded using liquid mercury strain gauges at 0 and 30 degrees knee flexion. The results of this study showed that anterior shear force on the proximal end of the tibia was the primary determinant of the strain in the AM bundle of the ACL, whereas neither pure knee internal-external rotation moment nor pure knee valgus-varus moment had significant effects on the strain of the AM bundle of the ACL. The results of this study further showed that anterior shear force at the proximal end of the tibia combined with a knee

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries valgus moment resulted in a significantly greater strain in the AM bundle of the ACL than did the anterior shear force at the proximal end of the tibia alone. Markolf et al5 also investigated effects of anterior shear force at the proximal end of the tibia and knee valgus, varus, internal rotation, and external rotation moments on the ACL loading of cadaver knees. A 100N anterior shear force and 10-Nm knee valgus, varus, internal rotation, and external rotation moments were added to cadaver knees. The ACL loading was recorded as the knee was extended from 90 degrees flexion to 5 degrees hyperextension. The results of this study showed that an anterior shear force on the tibia generated significant ACL loading, whereas the knee valgus, varus, and internal rotation moments also generated significant ACL loading only when the ACL was loaded by the anterior shear force at the proximal end of the tibia. The results of this study further showed that the ACL loading due to the anterior shear force combined with either a valgus or a varus moment to the knee was greater than that due to the anterior shear force alone, whereas the ACL loading due to the anterior shear force combined with a knee external rotation moment was lower than that due to anterior shear force alone. The knee valgus and external rotation moment loading are elements of dynamic valgus that many current ACL injury prevention programs are trying to avoid.3 The results of the study by Markolf et al5 also showed that ACL loading due to the combined knee varus and internal rotation moment loading was greater than that due to either knee varus moment loading or internal rotation moment loading alone and that the ACL loading due to combined knee valgus and external rotation moment loading was lower than that due to either knee valgus or external rotation moment loading alone. Finally, the results of this study showed that the ACL loading due to the anterior shear force and knee valgus, varus, and internal rotation moments increased as the knee flexion angle decreased. Fleming et al6 studied the effects of weight bearing and tibia external loading on ACL strain. They implanted a differential variable reluctance transducer to the AM bundle of the ACL of 11 subjects. ACL strains were measured in vivo when a subject's leg was attached to a knee loading fixture that allowed independent application of anteriorposterior shear force, valgus-varus moments, and internalexternal rotation moments to the tibia and simulation of weight-bearing conditions. The anterior shear force was applied on the proximal end of the tibia from 0N to 130N in 10-N increments. The valgus-varus moments were applied to the knee from 10 Nm to 10 Nm in 1-Nm increments. The internal-external rotation moments were applied to the knee from 9 Nm to 9 Nm in 1-Nm increments. The knee flexion angle was fixed at 20 degrees during the test. The results of this study showed that ACL strain significantly

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increased as the anterior shear force at the proximal end of the tibia and the knee internal rotation moment increased, whereas knee valgus-varus and external rotation moments had little effects on ACL strain under the weight-bearing condition. The previously mentioned studies consistently showed that the anterior shear force at the proximal end of the tibia is a major contributor to ACL loading, whereas the knee valgus, varus, and internal rotation moments may increase ACL loading when an anterior shear force at the proximal end of the tibia is applied. According to these ACL loading mechanisms, a small knee flexion angle, a strong quadriceps muscle contraction, or a great posterior ground reaction force can increase ACL loading. Quadriceps muscles are the major contributor to the anterior shear force at the proximal end of the tibia through the patella tendon. DeMorat et al7 demonstrated that a 4500-N quadriceps muscle force could create ACL injuries at 20 degrees knee flexion. Eleven cadaver knee specimens were fixed to a knee simulator and loaded with 4500-N quadriceps muscle force. Quadriceps muscle contraction tests at 400 N (Q-400 tests) and KT-1000 tests were performed before and after the 4500-N quadriceps muscle force loading. Tibia anterior translations were recorded during the Q-400 and KT-1000 tests. All cadaver knee specimens were dissected after all tests to determine the ACL injury states. Six of the 11 specimens had confirmed ACL injuries (three complete ACL tears and three partial tears). All specimens showed increased tibia anterior translation in Q-400 and KT-1000 tests. The result of this study also showed that quadriceps muscle contraction caused not only tibia anterior translation but also tibia internal rotation. Decreasing knee flexion angle increases the anterior shear force at the proximal end of the tibia by increasing the patella tendon–tibia shaft angle. With a given quadriceps muscle force, the anterior shear force at the proximal end of the tibia is determined by the patella tendon–tibia shaft angle, defined as the angle between the patella tendon and the longitudinal axis of the tibia.8 With a given quadriceps muscle force, the greater the patella tendon–tibia shaft angle, the greater the anterior shear force on the tibia. Nunley et al8 studied the relationship between the patella tendon–tibia shaft angle and knee flexion angle with weight bearing. Ten male and 10 female university students without known history of lower extremity injuries were recruited as the subjects. Sagittal plane x-ray films were taken for each subject at 0, 15, 30, 45, 60, 75, and 90 degrees knee flexion, bearing 50% of body weight. Patella tendon–tibia shaft angles were measured from the x-ray films. Regression analyses were performed to determine the relationship between patella tendon–tibia shaft angle and knee flexion angle and to compare the relationship between genders. The results 13

Anterior Cruciate Ligament Injury showed that the patella tendon–tibia shaft angle was a function of the knee flexion angle, with the patella tendon–tibia shaft angle increasing as the knee flexion angle decreased, and that on average the patella tendon–tibia shaft angle was 4 degrees greater in females than in males. The relationship between the patella tendon–tibia shaft angle and knee flexion angle obtained by Nunley et al8 was consistent with those from other studies on the patella tendon–tibia shaft angle under non–weight-bearing conditions.9–11 Decreasing the knee flexion angle also increases ACL loading by increasing the ACL elevation angle and deviation angle, defined as the angle between the longitudinal axis of the ACL and the tibia plateau and the angle between the projection of the longitudinal axis of the ACL on the tibia plateau and the posterior direction of the tibia, respectively.12 The resultant force along the longitudinal axis of the ACL equals the anterior shear force on the ACL divided by the cosines of the ACL elevation and deviation angles. The greater the ACL elevation and deviation angles, the greater the ACL loading with a given anterior shear force on the ACL. Li et al12 determined the in vivo ACL elevation and deviation angles as functions of the knee flexion angle with weight bearing. Five young and healthy volunteers were recruited as the subjects. The ACL elevation and deviation angles at 0, 30, 60, and 90 degrees knee flexion with weight bearing were obtained using individualized dual-orthogonal fluoroscopic images and magnetic resonance imaging (MRI)-based, three-dimensional (3D) models. The results of this study showed that both the ACL elevation and deviation angles increased as the knee flexion angle decreased. Several studies show that ACL loading increases as the knee flexion angle decreases. Arms et al13 studied the biomechanics of ACL rehabilitation and reconstruction and found that quadriceps muscle contraction significantly strained the ACL from 0 to 45 degrees knee flexion but did not strain the ACL when knee flexion was greater than 60 degrees. Beynnon et al14 measured the in vivo ACL strain during rehabilitation exercises and found that isometric quadriceps muscle contraction resulted in a significant increase in ACL strain at 15 and 30 degrees knee flexions but resulted in no change in ACL strain relative to the relaxed muscle condition at 60 and 90 degrees knee flexion. Li et al15,16 investigated the quadriceps and hamstring muscle loading on ACL loading and showed that the in situ ACL loading increased as the knee flexion angle decreased when quadriceps muscles were loaded, regardless of the hamstring muscle loading conditions. Literature also shows that individuals at high risk of sustaining noncontact ACL injuries have a smaller knee flexion angle during athletic tasks than do individuals at low risk. Epidemiological studies show that female athletes are at higher risk of sustaining noncontact ACL injuries than 14

their male counterparts.17–24 Recent biomechanical studies demonstrated that female recreational athletes exhibited small knee flexion angles in running, jumping, and cutting tasks.25,26 Studies also demonstrate that female adolescent athletes had a sharply increased ACL injury rate after age 13 years.27,28 A recent biomechanical study showed that female adolescent soccer players started decreasing their knee flexion angle during a stop-jump task after age 13 years.29 Taken together, these results suggest that small knee flexion angle during landing tasks may be a risk factor of sustaining noncontact ACL injuries. Increasing peak posterior ground reaction forces during athletic tasks increases ACL loading by inducing an increased quadriceps muscle contraction. A posterior ground reaction force creates a flexion moment relative to the knee, which needs to be balanced by a knee extension moment generated by the quadriceps muscles.30 As previously described, the quadriceps muscle contraction adds an anterior shear force on the proximal end of the tibia through the patella tendon. The greater the posterior ground reaction force, the greater the quadriceps muscle force and the greater the ACL loading.30 Cerulli et al31 and Lamontagne et al32 recently recorded in vivo ACL strain in a hop-landing task. A differential variable reluctance transducer was implemented on the middle portion of the AM bundle of the ACLs of three subjects through surgical procedures. Subjects then performed the hop-landing task in a biomechanics laboratory. Force plate, electromyography (EMG), and in vivo ACL strain were recorded simultaneously. The results of this study showed that the peak ACL strain occurred at the impact peak vertical ground reaction force shortly after initial contact between foot and ground. Yu et al30 demonstrated that peak impact vertical and posterior ground reaction forces occurred essentially at the same time. Taken together, these results suggest that a hard landing with a great impact posterior ground reaction force may be a risk factor of sustaining noncontact ACL injuries. Literature shows that individuals at a high risk of sustaining noncontact ACL injuries have greater peak posterior ground reaction forces in athletic tasks. Chappell et al26 studied the lower extremity kinetics as well as kinematics of university-age recreational athletes during landings of stop-jump tasks. Their results showed that female recreational athletes had greater peak resultant proximal tibia anterior shear force and knee joint resultant extension moment during landings of stop-jump tasks than did male recreational athletes. Yu et al studied the immediate effects of a newly designed knee brace with a constraint to knee extension during a stop-jump task.29–29b Their results showed that the university-age female recreational athletes had greater peak posterior ground reaction force during the landing of the stop-jump task than did their male

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries counterparts. Yu et al30 showed that the resultant peak proximal tibia anterior shear force was positively correlated to the peak posterior ground reaction force. Hamstring co-contractions protecting the ACL have been a longstanding clinical concept because hamstring muscles provide a posterior shear force on the tibia that is supposed to reduce the anterior shear force on the tibia from the patellar tendon and thus unload the ACL. Recent scientific studies, however, did not support this concept. Li et al15 showed in a cadaver study that hamstring cocontraction did not significantly decrease tibia anterior translation when the knee flexion angle was less than 30 degrees. Beynnon et al14 found that the isometric hamstring co-contraction of the hamstring muscles did reduce in vivo ACL strain between 15 and 60 degrees knee flexion. Kingma et al33 found that hamstring muscle activation increased only 1.3 to 2.0 times, whereas knee extension moment increased 2.7 to 3.4 times with a knee flexion angle between 5 and 50 degrees, which did not suggest a hamstring recruitment pattern to reduce the ACL loading. O'Connor,34 Pandy et al,35 and Yu et al29 all studied ACL loading using a modeling and computer simulation approach and showed that the hamstring muscles did not reduce ACL loading at all when the knee flexion angle was small. Although biomechanical studies showed that the knee valgus moment was not a major mechanism of ACL loading, a recent epidemiological study by Hewett et al3 reported that external knee valgus moment in a vertical drop landing–jump task was a predictor of ACL injuries. A total of 205 high school soccer, basketball, and volleyball players were followed for three competition seasons. Knee flexion and valgus angles at initial foot contact with the ground and the maximum knee flexion and valgus angles and maximum moments during the stance phase of the vertical drop landing–jump task were recorded prospectively for every subject. A total of nine subjects sustained ACL injuries after three competition seasons. The results of this study showed that knee abduction angle at landing was 8 degrees greater in ACL-injured than in uninjured athletes and that ACL-injured athletes had a 2.5 times greater peak external knee valgus moment and 20% higher peak vertical ground reaction force than did uninjured athletes. The results further showed that peak external knee valgus moment predicted ACL injury status with 73% specificity, 78% sensitivity, and a predictive R2 value of 0.88. The results of this study appear to suggest an association between knee valgus angle and moment with ACL injuries. However, we may have to be cautious when interpreting the association of knee valgus angle and moment with noncontact ACL injuries observed in the study by Hewett et al.3 The observed preinjury knee valgus moments of the nine subjects who suffered ACL injuries in this study

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were less than 0.12 Nm/body weight/standing height. The average body weight and stranding height of the injured subjects in this study were 62 kg and 1.68 m, respectively. This means that the preinjury knee valgus moments of the nine injured subjects in this study were less than 12.5 Nm. These knee valgus moment loadings were similar to those in the studies by Berns et al,4 Markolf et al,5 and Fleming et al,6 which demonstrated that knee valgus loading did not significantly affect ACL loading unless a significant proximal tibia anterior shear force was applied. Furthermore, several other studies in the current literature demonstrate that knee valgus moment loading alone cannot injure the ACL when the MCL is intact. Bendjaballah et al36 studied the effects of knee valgus-varus moment loading on cruciate and collateral ligament loadings using a finite element model. Their results suggest that cruciate ligaments are not major valgus-varus moment loading bearing structures when collateral ligaments are intact. Matsumoto et al37 investigated the roles of the ACL and MCL in preventing knee valgus instability using cadaver knees. Their results demonstrate that the MCL is the major structure to stop medial knee space opening. Mazzocca et al38 tested the effect of knee valgus loading on MCL and ACL injuries. They found that the response of the ACL strain to knee valgus moment loading was minimal when the MCL was intact but significantly increased after the MCL rupture began due to knee valgus moment loading. Their results show that the ACL still had about 60% of its original strength after complete MCL ruptures with medial knee space openings greater than 15 mm due to knee valgus moment loading. This study clearly demonstrates that a complete ACL rupture due to knee valgus moment loading without a complete MCL rupture (grade III injury) is unlikely, whereas clinical observations show that the majority of noncontact ACL injuries do not have significant MCL injuries. A recent study by Fayad et al39 showed that only 5 of a total of 84 contact and noncontact ACL injuries had complete MCL ruptures. Taken together, these studies suggest that knee valgus moment loading alone is not likely to be a major ACL loading mechanism that can result in ACL rupture or a major risk factor of sustaining noncontact ACL injuries. More scientific studies are needed before we can confidently interpret the association of knee valgus angle and moment with noncontact ACL injuries as a sole risk factor of sustaining noncontact ACL injuries. In summary, the current literature clearly suggests that sagittal plane biomechanics are the major mechanism of ACL loading. Decreased knee flexion angle and increased quadriceps muscle force and posterior ground reaction force causing an increased knee extension moment are requirements for increased ACL loading. Although the external knee valgus moment has been demonstrated to be associated 15

Anterior Cruciate Ligament Injury with ACL injuries, the current literature contains no evidence that knee valgus-varus and internal-external rotation moments can produce noncontact ACL injuries in and of themselves without these high sagittal plane forces.

References 1. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med 2005;39: 324–329. 2. Portney LG, Watkins MP. Foundations of clinical research: applications to practice, ed 2. Upper Saddle River, NJ, 2000, Prentice Hall Health. 3. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med 2005;33:492–501. 4. Berns GS, Hull ML, Paterson HA. Strain in the anterior medial bundle of the anterior cruciate ligament under combined loading. J Orthop Res 1992;10:167–176. 5. Markolf KL, Burchfield DM, Shapiro MM, et al. Combined knee loading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13:930–935. 6. Fleming BC, Renstrom PA, Beynnon BD, et al. The effect of weightbearing and external loading on anterior cruciate ligament strain. J Biomech 2001;34:163–170. 7. DeMorat G, Weinhold P, Blackburn T, et al. Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury. Am J Sports Med 2004;32:477–483. 8. Nunley RM, Wright D, Renner JB, et al. Gender comparison of patellar tendon tibial shaft angle with weight bearing. Res Sports Med 2003;11:173–185. 9. Smidt JG. Biomechanical analyses of knee flexion and extension. J Biomech 1973;6:79–82. 10. Buff HU, Jones LC, Hungerford DS. Experimental determination of forces transmitted through the patella-femoral joint. J Biomech 1988;21:17–23. 11. vanEijden TMGJ, De Boer W, Weijs WA. The orientation of the distal part of the quadriceps femoris muscle as a function of the knee flexion-extension angle. J Biomech 1985;18:803–809. 12. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 13. Arms SW, Pope MH, Johnson RJ, et al. The biomechanics of anterior cruciate ligament rehabilitation and reconstruction. Am J Sports Med 1984;12:8–18. 14. Beynnon BD, Fleming BC, Johnson RJ, et al. Anterior cruciate ligament strain behavior during rehabilitation exercises in vivo. Am J Sports Med 1995;23:24–34. 15. Li G, Rudy TW, Sakane M, et al. The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL. J Biomech 1999;32:395–400. 16. Li G, Zayontz S, Most E, et al. In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: an in vitro investigation. J Orthop Res 2004;22:293–297. 17. Ferretti A, Papandrea P, Conteduca F, et al. Knee ligament injuries in volleyball players. Am J Sports Med 1992;20:203–207. 18. Paulos LE. Why Failures Occur Symposium: revision ACL surgery, American Orthopaedic Society for Sports Medicine Eighteenth Annual Meeting, San Diego, CA, July 1992. 19. Malone TR, Hardaker WT, Garrett WE, et al. Relationship of gender to anterior cruciate ligament injuries in intercollegiate basketball players. J South Orthop Assoc 1993;2:36–39. 20. Pearl AJ. The athletic female, Champaign, IL, 1993, Human Kinetics, pp 302–303. 21. Irelan ML. Special concerns of the female athlete. Sports injuries: mechanism, prevention, and treatment, ed 2. Philadelphia, 1994, Williams & Wilkins, pp 153–187.

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22. Lindenfeld TN, Schmitt DJ, Hendy MP, et al. Incidence of injury in indoor soccer. Am J Sports Med 1994;22:354–371. 23. Woodford-Rogers B, Cyphert L, Denegar CR. Risk factors for anterior cruciate ligament injury in high school and college athletes. J Athl Train 1994;29:343–346. 24. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med 1995;23:694–701. 25. Malinzak RA, Colby SM, Kirkendall DT, et al. A comparison of knee joint motions patterns between men and women in selected athletic maneuvers. Clin Biomech 2001;16:438–445. 26. Chappell JD, Yu B, Kirdendall DT, et al. A comparison of knee kinetics between male and female recreational athletes in stop-jump tasks. Am J Sports Med 2002;30:261–267. 27. Yu B, Kirkendall DT, Taft TN, et al. Lower extremity motor controlrelated and other risk factors for noncontact anterior cruciate ligament injuries. Instruct Course Lect 2002;51:315–324. 28. Shea KG, Pfeiffer R, Wang JH, et al. Anterior cruciate ligament injury in pediatric and adolescent soccer players: an analysis of insurance data. J Pediatr Orthop 2004;24:623–628. 29. Yu B, McClure SB, Onate JA, et al. Age and gender effects on lower extremity kinematics of youth soccer players in a stop-jump task. Am J Sports Med 2005;33:1356–1364. 29a. Yu B, Herman D, Preston J, et al. Immediate effects of a knee brace with a constraint to knee extension on knee kinematics and ground reaction forces in a stop-jump task. Am J Sports Med 2004;32:1136–1143. 29b. Yu B, Lin CF, Garrett WE. Lower extremity biomechanics during the landing of a stop-jump task. Clin Biomech 2006;21:297–305. 30. Yu B, Chappell JD, Garrett WE. Authors’ response to letter to the editor. Am J Sports Med 2006;34:312–315. 31. Cerulli G, Benoit DL, Lamontagne M, et al. In vivo anterior cruciate ligament strain behavior during a rapid deceleration movement: case report. Knee Surg Sports Traumatol Arthrosc 2003;11:307–311. 32. Lamontagne M, Benoit DL, Ramsey DK, et al. What can we learn from in vivo biomechanical investigation of lower extremity? Proc XXIII Int Symp Biomech Sports 2005;49–56. 33. Kingma I, Aalbersberg S, van Dieen JH. Are hamstrings activated to counteract shear forces during isometric knee extension efforts in healthy subjects? J Electromyogr Kinesiol 2004;14:307–315. 34. O'Connor JJ. Can muscle co-contraction protect knee ligaments after injury or repair? J Bone Joint Surg Br 1993 Jan;75(1):41–48. 35. Pandy MG, Garner BA, Anderson FC. Optimal control of nonballistic muscular movements: a constraint-based performance criterion for rising from a chair. J Biomech Eng 1995 Feb;117(1):15–26. 36. Bendjaballah MZ, Shirazi-Adl A, Zukor DJ. Finite element analysis of human knee joint in varus-valgus. Clin Biomech 1997;12:139–148. 37. Matsumoto H, Suda Y, Otani T, et al. Roles of the anterior cruciate ligament and medial collateral ligament in preventing valgus instability. J Orthop Sci 2001;6:28–32. 38. Mazzocca AD, Nissen CW, Geary M, et al. Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament. J Knee Surg 2003;16:148–151. 39. Fayad LM, Parellada JA, Parker L, Schweitzer ME. MR imaging of anterior cruciate ligament tears: is there a gender gap? Skeletal Radiol 2003;32:639–646.

Suggested Readings Boden BP, Dean GS, Feagin JA, et al. Mechanisms of anterior cruciate ligament injury. Ortho 2000;23:573–578. Caraffa A, Cerulli G, Projetti M, et al. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthrosc 1996;4:19–21. Chappell JD, Herman DC, Knight BS, et al. Effect of fatigue on knee kinetics and kinematics in stop-jump tasks. Am J Sports Med 2005;33:1022–1029.

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries Kanamori A, Woo SLY, Ma CB, et al. The forces in the anterior cruciate ligament and knee kinematics during a simulated pivot shift test: a human cadaveric study using robotic technology. J Arthroscop Relat Surg 2000;16:633–639. Li G, Rudy TW, Sakane M, et al. The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in ACL. J Biomech 1999;32:395–400. Myklebust G, Engebretsen L, Braekken IH, et al. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sports Med 2003; 13:71–78.

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Olsen O-E, Myklebust G, Engebretsen L, et al. Injury mechanisms for anterior cruciate ligament injuries in team handball. Am J Sports Med 2004;32:1002–1012. Petersen W, Braun C, Bock W, et al. A controlled prospective case control study of a prevention training program in female team handball players: the German experience. Arch Orthop Trauma Surg 2005;125:614–621. Soderman K, Werner S, Pietila T, et al. Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players? A prospective randomized intervention study. Knee Surg Sports Traumatol Arthrosc 2000;8:356–363.

17

3

CHAPTER

Letha Y. Griffin James Kercher

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury INTRODUCTION In the past decade, there has been an increased emphasis on injury prevention in sports. However, a significant difficulty with designing prevention programs for anterior cruciate ligament (ACL) injury is our incomplete understanding of risk factors and mechanism of injury. Two different schemes exist for classifying risk factors. Risk factors can be divided into intrinsic factors, meaning those unique to the individual such as anatomy, muscle strength, and balance, and extrinsic factors, which are external influences on the body including such factors as shoe-surface interactions, braces, and weather conditions. Risk factors can also be categorized as environmental, anatomical, hormonal, neuromuscular, and genetic. The latter classification scheme will be the basis for this discussion.

ENVIRONMENTAL RISK FACTORS Many environmental risk factors specific to ACL injury have been studied, including weather and playing conditions, shoe-surface interaction, footwear, and bracing. These variables are important because they represent potentially avoidable risk factors. The foot plant, the shoe, the surface, and the shoe-surface interaction are critical factors in noncontact ACL injuries. Basic physics describes static and kinetic frictional forces between two bodies. Energy is dissipated once the static frictional force is overcome, allowing movement. This 18

is termed sliding, which causes a shift from static to kinetic frictional force that is more readily overcome. It is logical to assume that during foot plant, characteristics that increase static frictional force between the foot and ground will create higher-energy forces in the lower extremity. Certain studies have examined surface conditions relating to ACL injuries. Olsen et al1 and Torg et al2 both studied team handball and found an increased risk of ACL injury while playing on synthetic floors versus traditional parquet floors. Both believed that the increased friction of synthetic flooring was the cause. Orchard et al,3 Heidt et al,4 and Scranton et al5 all reported higher rainfall and cooler temperatures were related to decreased ACL injuries and theorized that dry, hot weather conditions promote increased frictional forces on the playing field, thus in turn resulting in increased injury rates. Lambson et al6 in a 3-year prospective study looked at footwear to evaluate torsional resistance of modern football cleats. They compared four styles of football shoes and found that the edge design, a design having longer irregular cleats at the periphery and many smaller cleats interiorly, was associated with higher ACL injury rates.

Bracing Pros and Cons Prophylactic and functional (postreconstructive) knee bracing has long been a controversial subject. Over the past 20 years, attitudes have fluctuated regarding the effectiveness of braces in preventing knee injury in the uninjured athlete,

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury the ACL deficient athlete, and the ACL reconstructed athlete. A study by Decoster and Vailas7 on brace prescriptions patterns noted that there has been a decreasing tendency for orthopaedic surgeons to prescribe ACL braces. The authors also noted that a primary factor influencing brace prescription by orthopaedists was the activity level of the patient.7 Early studies on prophylactic brace wear by Teitz et al8 and Rovere et al9 indicated no benefit to brace wear. These authors cited increased rates of knee injury in some athletes using prophylactic knee braces. In contrast, two other studies—the West Point study by Sitler et al10 involving 1396 cadets at the U.S. Military Academy who played intramural tackle football and the Big Ten Conference study by Albright et al11 involving 987 NCAA football players— concluded that prophylactic knee braces were effective in reducing injury. Since these studies, there has been a paucity of data to support prophylactic bracing for ACL injury protection, but it is believed that braces may provide some advantage to reducing medial collateral ligament (MCL) injury.12,13 Braces are commonly prescribed following ACL injury or reconstruction; however, little evidence supports their physiological or biomechanical efficacy. In a prospective randomized clinical trial of functional bracing for ACL deficient athletes, Swirtun et al14 found that subjectively, patients had initial sense of increased stability, but these investigators were unable to find objective benefits. In contrast, Kocher et al studied the use of braces to prevent reinjury in 180 ACL deficient alpine skiers and found reinjury occurred in 2% of the braced skiers compared with 13% of the unbraced “control” skiers.15 Risberg et al investigated the effect of knee bracing after ACL reconstruction in a prospective clinical trial of 60 patients randomized postoperatively (30 braced and 30 without brace) with 2 years of follow-up.16 They found no evidence that bracing affected knee joint laxity, range of motion, muscle strength, functional knee tests, patient satisfaction, or pain in braced athletes compared with athletes who did not use a brace following ACL reconstruction. Furthermore, they found prolonged bracing, which they defined as brace wear 1 to 2 years postoperatively, produced decreases in quadriceps muscle strength. McDevitt et al in a prospective, randomized multicenter study of 100 subjects likewise found no significant differences between braced and nonbraced subjects following ACL reconstruction.17 It has been theorized that damage to the ACL can disrupt mechanoreceptors in the knee leading to decreased proprioception.18 Birmingham et al19 has suggested that brace wear may help to correct this deficit somewhat, but benefits do not carry over to more demanding tasks. To examine knee proprioception, researchers have studied the threshold for detection of passive knee motion and found that brace application to the ACL deficient limb does not improve the threshold to detect passive range of motion.20,21

3

Although the preponderance of evidence would suggest that braces are ineffective in protecting the ACL deficient or reconstructed athletic knee, many patients still wish for a brace because they subjectively report that braces increase their confidence during sports participation.

ANATOMICAL RISK FACTORS Recognition of disparities in noncontact ACL injury rates between men and women has led to much debate on the association of gender-specific anatomical differences as potential injury risk factors. Proposed anatomical risk factors include increased quadriceps femoris angle (Q angle), ligamentous laxity in apparent knee valgus, femoral notch size, ACL geometry, subtalar joint pronation, and body mass index (BMI).

Association Between Q Angle and Injury Risk The Q angle, which typically ranges from 12 to 15 degrees, is formed by the intersection of two lines, one from the anterior superior iliac spine to the midpoint of the patella and another from the tibial tubercle to the same reference point on the patella. It has been proposed that an increased Q angle may be associated with an increased risk for knee injury because excessive lateral forces could negatively influence the knee's mechanical alignment.22,23 Females have been reported to have larger Q angles than their male counterparts24,25; however, in a trigonometric evaluation, Grelsamer et al reported a mean difference of only 2.3 degrees between the Q angles of men and women and furthermore found that men and women of equal height demonstrated similar Q angles.26 Shambaugh et al25 studied the relationship between lower extremity alignment and injury rates in recreational basketball players and found larger Q angles in athletes who sustained knee injures. In contrast, other authors have not been able to relate injury to Q angle.22,27,28 Guerra et al29 reported that quadriceps contraction alters Q angle measurements, thus making it difficult to establish a direct link between static Q angle measurements and injury.

Notch Width as a Risk Factor Structural characteristics of the distal femur and femoral intercondylar notch as well as ACL geometry and the ACL relationship to the intercondylar notch have been implicated as anthropometric factors associated with ACL injury rate disparity between males and females. It has been postulated that a smaller notch, termed notch stenosis, may cause impingement to the ACL and put it at increased risk 19

Anterior Cruciate Ligament Injury of injury, or possibly a smaller notch may imply a smaller ACL leading to decreased load to failure. Although these factors have been heavily studied using plain radiography,30–38 computed tomography (CT),39,40 magnetic resonance imaging (MRI),41,42 and cadaveric43-45 and in vitro37 analysis, a lack of consistent measurement techniques and findings has made it difficult to interpret results. Therefore there is still no consensus relating morphology of the intercondylar notch to ACL injury rates. A chronological summary of the data is listed in Table 3-1.

HORMONAL RISK FACTORS The increased incidence of ACL injury in women compared with men has raised interest regarding the influence of sex hormones on injury occurrence. Fig. 3-1 describes the menstrual cycle. A normal cycle is typically 28 to 30 days. The follicular phase (i.e., the stage of the follicle development) begins with menstruation and ends with ovulation. The latter lasts approximately 3 to 5 days and, if pregnancy does not occur, is followed by the luteal phase, which begins with the involution of the follicle and formation of the corpus luteum. Estradiol secretion is biphasic, peaking in both the follicular and luteal stages. Progesterone is produced by the corpus luteum and therefore occurs in the luteal phase only.

Monthly Distribution of Anterior Cruciate Ligament Injuries Initial surveys of injury occurrence throughout the monthly menstrual cycle revealed that injuries were not equally distributed throughout the cycle but instead were clustered either around menstruation or the ovulation period of the cycle.46–48 However, the reliability of these early data was questioned because subjects were not frequently controlled for the use of birth control pills and hormonal assays were not done

to verify cycle times; instead, athletes recalled or reported their menstrual history. Repeated studies using radioimmunoassays on serum, urine, or saliva verified the non–chance distribution of ACL injuries throughout the menstrual cycle.48–51

Sex Hormones and Laxity If sex hormone levels do influence injury rates, how this occurs is not clear. Multiple studies in the past decade have focused on the influence of sex hormones on knee laxity, and some investigators have even correlated female sex hormone levels and laxity measures with menstrual cycle phase. In 1999, Wojtys and Huston52 reported on a seriescontrolled study of 12 females and 12 males, in which they found a decrease in knee laxity on day 12 of the monthly menstrual cycle in women versus no monthly variation in knee laxity in men. In the following year, however, Belanger et al53reported no significant difference in anterior knee laxity throughout the monthly cycle in 18 Brown University athletes studied over 10 weeks. Similarly, Karageanes et al54 reported no significant changes in ACL laxity from the follicular to luteal phases. This research group measured laxity before workouts in 26 athletes, comparing these data to self-charted menstrual cycles. Van Lunen et al,55 using a within-subjects linear model, reported on 12 females tested for knee laxity at the onset of menses, near ovulation, and on day 23 with hormonal assays performed on blood drawn on those same days. They found no association between follicular, ovulatory, or luteal phase hormone concentrations and ACL laxity measures. This is in contrast to an earlier study by Heitz et al,56 who not only compared laxity measures taken on days 1, 10, 11, 12, 13, 20, 21, 22, and 23 of a self-reported menstrual cycle but also compared these data with serum estradiol and progesterone levels as measured by immunoassays in seven active females who reported normal 28- to 30-day menstrual cycles. These investigators found a significant difference in anterior knee laxity when comparing laxity

Proliferative phase (uterus) Follicular phase (ovary)

LH

Menstrual phase

Progestational phase (uterus) Luteal phase (ovary)

te es

ro

ne

og

Pr FSH Estrogen

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 Ovulation Menses Menses FIG. 3-1 A normal menstrual cycle. FSH, Follicle stimulating hormone; LH, luteinizing hormone.

20

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury

3

TABLE 3-1 Studies Evaluating Notch Size as an Anterior Cruciate Ligament (ACL) Injury Risk Factor Year Author

Study

Design

Conclusion

Comments

1987 Anderson

Analysis of the intercondylar

Retrospective study. Compared

Significant association between

Notchplasty for

notch by computed

bilateral ACL tears, unilateral tears,

anterior outlet stenosis and

those with

tomography

and normal knees in males and

unilateral and bilateral ACL tears.

documented

females using computed

No gender differences found.

stenosis

et al39

tomography (CT) scan. 1987 Houseworth et al40

The intercondylar notch in acute Retrospective study using computer Narrowed posterior arch of the

Positive

tears of the anterior cruciate

graphic analysis of notch-view

notch may predispose a knee to

association

ligament

radiographs in 50 patients with an

ACL tear.

between notch

acute ACL injury and 50 normal

and injury but no

knees.

comment on gender

112

1988 Souryal et al

Bilaterality in ACL injuries:

Retrospective analysis of 1120

associated intercondylar notch

patients with ACL ruptures. Devised bilateral group compared with

association

stenosis

notch width index (NWI) to

between notch

NWI was significantly less for unilateral and normal knees.

Positive

compare notch widths on

and injury but no

radiographs.

comment on gender

1993 Souryal et al38

Intercondylar notch size in ACL

Prospective blind study of 902 high Athletes with stenotic notch have

Females had

injuries in athletes

school athletes. ACL injuries were

greater risk for noncontact ACL

significantly

recorded and correlated with NWI.

injury. Limit of “critical stenosis”

smaller NWI

was NWI of <0.20 for males and <0.18 for female subjects. 1993 Schickendantz 36

et al

Predictive value of radiographs

Retrospective radiographic study of Size of notch probably a factor in

in the evaluation of unilateral

250 patients with ACL injuries.

ACL injuries, but plain radiographs measurements

and bilateral ACL injuries

Compared unilateral ACL injury,

cannot be used reliably to

Notch should not be

bilateral ACL injury, and noninjured diagnose clinically significant

used to predict

subjects.

potential for ACL

stenosis.

injury 1994 Lund-Hassen et al33

Intercondylar notch width and

A case-control study of 46 female

Notch widths of less than 17 mm

NWI is predictive

the risk for ACL rupture

handball players.

were six times more likely to

of injury

sustain ACL injury. 31

1994 LaPrade et al

Femoral intercondylar notch

Prospective study of 213 athletes. 7 Athletes with a stenotic notch

ACL within a

stenosis and correlation to ACL

ACL tears (4 male, 3 female).

were at significant risk of ACL

stenotic notch

rupture. No statistical difference

may be coupled

injuries

between gender of the athlete and with an inherently NWI. 1997 Muneta et al44

smaller ACL

Intercondylar notch width and

A cadaveric knee study. 16 knees (8 Knees with smaller NWI did

Impingement may

its relation to the configuration

male, 8 female). Notch and ACL

be due to

and cross-sectional area of the

dimensions were measured.

ACL

contain thinner ACLs.

mismatch between size of ACL and notch volume continued

21

Anterior Cruciate Ligament Injury TABLE 3-1 Studies Evaluating Notch Size as an Anterior Cruciate Ligament (ACL) Injury Risk Factor—Cont'd Year Author

Study

Design

Conclusion

Comments

1998 Shelbourne

The relationship between

Prospective study. Intraoperative

et al37

Females have smaller notch

Notch but may

intercondylar notch width of the measurements were taken on 714

widths. After both had

reflect smaller ACL

femur and incidence of ACL

ACL (480 male, 234 female)

reconstructions with equally sized

tears

reconstructions. Patients who

autografts, there was no difference

subsequently tore their contralateral in graft tear rate. Also found that ACL or graft were recorded.

NWI is not effective for standardizing people of differing heights.

2001 Anderson et al41

2001 Rizzo et al45

30

2001 Ireland et al

Correlation of anthropometric

Prospective study of 100 matched

No statistically significant

Notch width did

measurements, strength, ACL

high school basketball players (50

difference in NWI between sexes.

not standardize

size, and intercondylar notch

males and 50 females). Examined

ACL was smaller in females but did equally between

characteristics to sex differences for body fat analysis, muscle

not vary in proportion to notch. No males and females

in ACL tear rates

strength, and magnetic resonance

evidence indicating difference in

imaging (MRI) of the notch and

notch characteristics and sex

cross-sectional area of the ACL.

differences in ACL tears.

Comparison of males' and

Cadaveric study. 15 male knees and Significant difference between

females' ratios of ACL width to

11 female knees.

of different sizes

Females have

male and female ACL widths; ACL: smaller ACL:FIN

femoral intercondylar notch

FIN width ratio which was smaller ratios

(FIN) width

in females.

A radiographic analysis of the

Retrospective study. Notch-view

Smaller notch width and NWI in

Smaller notch

relationship between the size

radiographs from 108 subjects (55

ACL-injured patients regardless of

dimensions at

and shape of the intercondylar

females, 53 males) with ACL injuries notch shape or gender. A-shaped

greater risk of

notch and ACL injury

and 186 with intact ACLs (94

injury

notches were smaller.

females, 92 males). 2002 Tillman et al41a Differences in three

Cadaveric skeletal study of 100 male The intercondylar notch appears

ACL geometry

intercondylar notch geometry

and 100 female skeletons. 3 indices less round in females.

may be the cause

indices between males and

of notch geometry were calculated

of increased ACL

females

using digital photographs: NWI,

injury in females

notch area index, and notch shape index. 42

2002 Charlton et al

Differences in femoral notch

MRI study of 48 asymptomatic

Volume of the ACL located inside

anatomy between males and

subjects (20 females, 28 males).

the femoral notch was significantly smaller ACLs and

females

Analyzed notch morphology.

smaller in females. Subjects with

Females may have smaller notches

smaller notch volumes have smaller ACLs. 2005 Chandrashekar et al43

Sex-based differences in the

Cadaveric study of 20 knees (10

No difference in notch geometry

anthropometric characteristics

males, 10 females). Notch and ACL

between males and females. ACLs females

of the ACL and its relation to

were examined using

in females were smaller in length,

intercondylar notch geometry

three-dimensional (3D) imaging.

cross-sectional area, volume, and mass when compared with ACLs in males.

22

Smaller ACLs in

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury measures at baseline estrogen levels with peak levels of estrogen and when comparing laxity at baseline progesterone levels with that of peak progesterone levels. These results are similar to a series-controlled Japanese study57 involving 16 women and 8 men, which found no statistical difference in anterior displacement over time in men but did find variation in anterior knee laxity in women between the follicular and ovulatory phases and between the follicular and luteal phases at 89N displacement. Furthermore, Shultz et al58 obtained daily knee laxity measures as well as assayed daily serum samples for estradiol, progesterone, and testosterone in 25 females throughout one complete menstrual cycle and concluded that changes in sex hormones mediated changes in knee laxity across the menstrual cycle. Moreover, these investigators found a variable knee laxity response among females, with some females experiencing significant variation in knee laxity across the monthly cycle and others experiencing very little. Even if an association can be demonstrated among sex hormones, menstrual phase, and increased laxity, an increase in knee laxity has not been reliably associated with an increased risk of ACL injury.59–62

Sex Hormones and Ligament Biology Female sex hormones have been found in animal and human studies to have a direct effect on growth and development of bone, muscle, and connective tissue. In 1996, Liu et al63 reported receptor sites for estrogen and progesterone in the human ACL, and in 2005, Lovering and Romani reported androgen receptors in the female ACL as well, suggesting that these sex hormones could have a direct effect on the structure and composition of the ACL.64 In fact, in 1997, Liu et al reported a significant reduction in procollagen synthesis by ACL fibroblasts and in fibroblast proliferation with increasing estradiol concentrations.65 Similarly, Slauterbeck et al66 found that high-dose 17b-estradiol significantly decreased the tensile strength of the ACL in ovariectomized rabbits compared with the tensile strength of the ACL in ovariectomized rabbits not supplemented with estrogen. Seneviratne et al67 reported that despite the presence of estrogen receptors on ovine ACL fibroblasts, there was no significant difference in ACL fibroblast proliferation or collagen synthesis when cells in culture were exposed to 17b-estradiol at physiological concentrations. In 2003, Strickland et al,68 in a controlled laboratory study of 38 matured ewes, found that estrogen or a selective estrogen receptor agonist at physiological levels did not result in a change in the mechanical properties of the sheep's knee ligament. Arendt et al69 mechanically tested ACLs of 26 young rhesus monkeys (14 ovariectomized and 12 shamoperated) and concluded that estrogen had no effect on the

3

mechanical or material properties of the ACL in these primates.

Sex Hormones and Other Concerns Perhaps sex hormones influence ACL injuries not by a direct effect on the mechanical properties of the ligament but on other injury-associated parameters such as balance, muscle response time, mood, and focus.70,71 Estrogen and progesterone have been found to influence the cardiovascular system, blood pressure, heart rate, minute ventilation, substrate metabolism, thermal regulation, resting O2 consumption, and other factors.72,73 Variable results regarding anaerobic performance and the menstrual cycle have been reported, with some researchers claiming no change in anaerobic ability across the cycle and others claiming greater anaerobic capacity and peak power during the luteal phase.74 Wojyts and Huston52 investigated the variations in strength, endurance, and time to peak torque in 12 women on days 1, 12, and 24 of a complete cycle and found no significant variation in any of these factors across the menstrual cycle. Schultz et al have made the thoughtful statement that although we do not know how the impact of the menstrual cycle affects noncontact ACL injuries, the preponderance of evidence favors the idea that the incidence of noncontact ACL injuries does vary throughout the monthly cycle and does not occur by chance alone. Therefore, one has to question the validity of data accumulated in women regarding other risk factors for ACL injury that do not take into account the time of the monthly menstrual cycle during which the data were obtained.75 In summary, research in the area of sex hormones' effects on ACL injury rates has been intense in the last several years, but many questions remain unanswered.

NEUROMUSCULAR RISK FACTORS The majority of ACL injuries occur without direct contact made to the player's knee. Players may describe a bump or a hit to another body area that throws them off balance (a perturbation), but in more than 70% of ACL injuries, a noncontact mechanism has been identified.27,47,76–78 Moreover, interviews with players and analysis of injury videotapes from basketball, soccer, football, and volleyball have revealed that most injuries occur with decelerating, as when stopping, cutting, changing directions, or landing a jump.79–81 However, the exact mechanism—that single action or cascade of events that ultimately results in an ACL injury— is still largely unknown. Markolf et al,82 using fresh frozen cadavers, applied combined loads to the tibia and measured the effects on the ACL through a wide range of motion angles. These researchers found that a combination of 23

Anterior Cruciate Ligament Injury internal rotation and anterior tibial force resulted in the highest load to the ACL. Earlier, Markolf et al had reported that the ACL experienced large loads when the knee was near straight (i.e., at angles between 0 and 20 degrees of flexion).83 The most detailed analysis of the mechanism of ACL injury has been in alpine skiing, where videotape analysis of ACL injuries has revealed two potential mechanisms of injury.84,85 The most common is the so-called “phantom foot mechanism” that occurs when the skier falls or sits backwards, catching the inside edge of the tail of the ski, which results in internal rotation of the tibia with the knee flexed well beyond 90 degrees. The second injury mechanism in skiing occurs with a hard, off-balance landing. In this scenario, the skier's boot “pushes” the tibia forward on landing, increasing the load on the ACL. Garrett has suggested that a large eccentric quadriceps contraction with the knee in slight flexion can result in sufficient force to tear the ACL; in other words, the quadriceps could be the intrinsic force in a noncontact ACL injury.85a This theory was investigated in a laboratory study by DeMorat et al86 using 13 fresh frozen potted knees held in 20 degrees of flexion. A 4500N quadriceps force anteriorly displaced the tibia, resulting in damage to the ACL in 11 knees and gross disruption of this ligament in 6 of these 11 knees. Two knees sustained tibial plateau fractures. It is known that joint stability is provided not only by the static ligament restraints but also by dynamic muscle contraction. In fact, Markolf reported that patients who were not athletes could increase varus and valgus knee stiffness by twofold to fourfold with isometric contraction of the hamstrings and quadriceps.87 Women have been found to be less able to stiffen their knees through muscle contraction than men, a factor that may place women at greater risk for ACL injury when compared with men.88–90 A study by Wojtys et al90 employing 23 volunteers (10 men and 13 women who were selected to participate because they had healthy but “loose knees” [i.e., a manual maximal anterior arthrometric laxity measurement of at least 6 mm]) found that maximal co-contraction of the knee significantly decreased mean anterior tibial translation in all volunteers, but the percent increase in sheer stiffness of the knee was greater in men (P ¼ 0.003). This same research group earlier studied 10 elite female athletes and 10 elite male athletes with sex-matched, nonathlete controls and reported that female athletes compared with male athletes took longer to generate maximal hamstring muscle torque during isokinetic testing and contracted their quadriceps, rather than their hamstrings, as an initial response to anterior tibial translation. Overall, females had less strength and endurance than males and had greater anterior tibial laxity.91 Not only do women demonstrate variations in strength, laxity, and muscle recruitment, but a number of researches 24

have reported that women perform cutting maneuvers and land jumps in a more upright posture—a posture shown by Markolf et al to put greater strain on the ACL.82,83,92–98 In contrast, in 1996 Hewett et al99 reported no difference in knee flexion angles on landing between males and females, and Fagenbaum and Darling evaluated eight females and six male varsity collegiate basketball players and reported that women landed with increased knee flexion angles.100 Recently, several research groups have used threedimensional (3D) kinematics to evaluate landing and cutting movements.101–105 McLean et al evaluated side-stepping in 10 male and 10 female collegiate athletes and found women had significant larger normalized knee valgus moments than males.103 These findings are consistent with other researchers who reported larger knee valgus motions in women compared with men performing side-step cutting maneuvers96 and are also consistent with greater valgus motion reported in women doing jump-landing tasks.106,107 Researchers have also emphasized the relationship of knee position to neuromuscular control of the hip. They believe that knee valgus moments are related to hip flexion and internal rotation on contact during side-stepping,102 a relationship previously emphasized by Kibler.108 Ford et al,109 using 3D kinematic analysis of 81 high school basketball athletes (47 females and 34 males) performing a drop–vertical jump maneuver, reported that females landed with greater total valgus knee motion and a greater maximal valgus knee angle than male athletes. Moreover, this same group of researchers prospectively examined 205 female soccer, basketball, and volleyball players performing a jump-landing task and reported that of these 205 subjects, 9 sustained an ACL injury during the time of the study.107 These 9 subjects had a knee abduction angle on landing of 8 degrees greater (P > 0.05) than uninjured athletes and a 2.5 times greater knee abduction moment (P < 0.001) and 20% higher ground reaction force (P < 0.05) than those who did not sustain an ACL injury. Three-dimensional kinematic and kinetic analysis was used for the study. Increased valgus knee movements in female recreational athletes during the landing phase of vertical and backward jumping were also reported by Chappell et al,92 but this research group found no difference in the magnitude of the knee varus-valgus moments between genders. These researchers also reported that female recreational athletes had an increased proximal tibial anterior sheer force during the landing phase in a stop-jump task compared with male recreational athletes. In their investigation of gender differences in 3D hip and knee joint mechanics in college athletes performing five randomly cued cutting trials, Pollard et al found no gender differences in selected peak hip and knee joint kinematics and movements, except in peak hip abduction, where

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury females demonstrated significantly less peak hip abduction than did males.105 The variable responses reported by investigators with regard to neuromuscular risk factors in female athletes may be related to the relatively small cohort size in many studies, variations between recreational and elite athletes, or age group variations in the athletes tested. Moreover, most researchers compared gender differences, and perhaps the differences or variations in neuromuscular parameters exist among members of the same gender, not merely between genders. Further clarification is needed through additional research efforts.

FAMILIAL TENDENCY TO NONCONTACT ANTERIOR CRUCIATE LIGAMENT INJURY In a retrospective study published in 1994, Harner et al110 compared 31 patients who sustained bilateral ACL injuries with 23 matched control subjects (i.e., no history of ACL injury) and reported a significant increase (P < 0.01) in the ACL incidence rate among immediate family members of the 31 ACL-injured patients compared with the controls. Similarly, Flynn et al111 compared 171 ACL-injured subjects with 171 matched controls and found that ACL-injured patients were twice as likely to have relatives who had sustained an ACL injury compared with the controls (adjusted odds ratio ¼ 2.00; 95% confidence interval, 1.19–3.33).

SUMMARY Despite the plethora of research on gender-specific risk factors for ACL injury over the past several decades, there remains no conclusive evidence of a direct cause-and-effect relationship. It is known that females have increased ACL injury rates. Perhaps this represents the interplay of several risk factors resulting in a cumulative effect. Further research is warranted.

References 1. Olsen OE, Myklebust G, Engebretsen L, et al. Relationship between floor type and risk of ACL injury in team handball. Scand J Med Sci Sports 2003;13:299–304. 2. Torg JS, Stilwell G, Rogers K. The effect of ambient temperature on the shoe-surface interface release coefficient. Am J Sports Med 1996;24:79–82. 3. Orchard J, Seward H, McGivern J, et al. Rainfall, evaporation and the risk of non-contact anterior cruciate ligament injury in the Australian Football League. Med J Aust 1999;170:304–306. 4. Heidt RS, Dormer SG, Cawley PW, et al. Differences in friction and torsional resistance in athletic shoe-turf surface interfaces. Am J Sports Med 1996;24:834–842. 5. Scranton PE, Whitesel JP, Powell JW, et al. A review of selected noncontact anterior cruciate ligament injuries in the National Football League. Foot Ankle Int 1997;18:772–776.

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6. Lambson R, Barnhill B, Higgins R. Football cleat design and its effect on anterior cruciate ligament injuries. Am J Sports Med 1996;24:155–159. 7. Decoster LC, Vailas JC. Functional anterior cruciate ligament bracing: a survey of current brace prescription patterns. Orthopedics 2003;26:701–706; discussion, 706. 8. Teitz C, Hermanson B, Kronmal R, et al. Evaluation of the use of braces to prevent injury to the knee in collegiate football players. J Bone Joint Surg Am 1987;69:2–8. 9. Rovere G, Haupt H, Yates C. Prophylactic knee bracing in college football. Am J Sports Med 1987;15:111–116. 10. Sitler M, Ryan J, Hopkinson W, et al. The efficacy of a prophylactic knee brace to reduce knee injuries in football. A prospective randomized study at West Point. Am J Sports Med 1994;18:310–315. 11. Albright J, Powell J, Smith W, et al. Medial collateral ligament knee sprains in college football. Am J Sports Med 1994;22:12–18. 12. Albright JP, Saterbak A, Stokes J. Use of knee braces in sport. Current recommendations. Sports Med 1995;20:281–301. 13. Najibi S, Albright JP. The use of knee braces, part 1: prophylactic knee braces in contact sports. Am J Sports Med 2005;33:602–611. 14. Swirtun LR, Jansson A, Renstrom P. The effects of a functional knee brace during early treatment of patients with a nonoperated acute anterior cruciate ligament tear: a prospective randomized study. Clin J Sport Med 2005;15:299–304. 15. Kocher MS, Sterett WI, Briggs KK, et al. Effective functional bracing on subsequent knee injury in ACL deficient professional skiers. J Knee Surg 2003;16:87–92. 16. Risberg MA, Holm I, Steen H, et al. The effect of knee bracing after anterior cruciate ligament reconstruction. A prospective, randomized study with two years' follow-up. Am J Sports Med 1999;29:76–83. 17. McDevitt ER, Taylor DC, Miller MD, et al. Functional bracing after anterior cruciate ligament reconstruction: a prospective, randomized, multicenter study. Am J Sports Med 2004;32:1887–1892. 18. Lephart SM, Kocher MS, Fu FH, et al. Proprioception following anterior cruciate ligament reconstruction. J Sport Rehabil 1992;1:188–196. 19. Birmingham TB, Kramer JF, Kirkley A, et al. Knee bracing after ACL reconstruction: effects on postural control and propriception. Med Sci Sports Exerc 2001;33:1253–1258. 20. Beynnon BD, Good L, Risbert MA. The effect of bracing on proprioception of knees with anterior cruciate ligament injury. J Orthop Sports Phys Ther 2002;32:11–15. 21. Risberg MA, Beynnon BD, Peura GD, et al. Proprioception after anterior cruciate ligament reconstruction with and without bracing. Knee Surg Sports Traumatol Arthrosc 1999;7:303–309. 22. Duffey ML, Martin DF, Cannon DW, et al. Etiologic factors associated with anterior knee pain in distance runners. Med Sci Sports Exerc 2000;32:1825–1832. 23. Heiderscheit BC, Hamill J, Van Emmerik RE. Q-angle influences on the variability of lower extremity coordination during running. Med Sci Sport Exerc 1999;31:1313–1319. 24. Heiderscheit BC, Hamill J, Caldwell GE. Influence of Q-angle on lowerextremity running kinematics. J Orthop Sports Phys Ther 2000;30:271–278. 25. Shambaugh JP, Klein A, Herbert JH. Structural measures as predictors of injury in basketball players. Med Sci Sports Exerc 1991;23:522–527. 26. Grelsamer RP, Dubey A, Weinstein CH. Men and women have similar Q angles: a clinical and trigonometric evaluation. J Bone Joint Surg Br 2005;87:1498–1501. 27. Gray J, Taunton J, McKinzie D, et al. A survey of injuries to the anterior cruciate ligament of the knee in female basketball players. Int J Sports Med 1985;6:314–316. 28. Myer GD, Ford KR, Hewett TE. The effects of gender on quadriceps muscle activation strategies during a maneuver that mimics a high ACL injury risk position. J Electromyogr Kinesiol 2005;15:181–189. 29. Guerra JP, Arnold MJ, Gajdosik RL. Q angle: effects of isometric quadriceps contraction and body position. J Orthop Sports Phys Ther 1994;19:200–204.

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Anterior Cruciate Ligament Injury 30. Ireland ML, Ballantyne BT, Little K, et al. A radiographic analysis of the relationship between the size and shape of the intercondylar notch and anterior cruciate ligament injury. Knee Surg Sports Traumatol Arthrosc 2001;9:200–205. 31. LaPrade R, Burnett Q. Femoral intercondylar notch stenosis and correlation to anterior cruciate ligament injuries. Am J Sports Med 1994;22:198–203. 32. Lombardo S, Sethi PM, Starkey C. Intercondylar notch stenosis is not a risk factor for anterior cruciate ligament tears in professional male basketball players: an 11-year prospective study. Am J Sports Med 2005;33:29–34. 33. Lund-Hassen H, Gannon J, Engebretsen L, et al. Intercondylar notch width and risk of ACL rupture in female varisty team handball players. A case control study. Acta Orthop Scand 1994;65:529–532. 34. Norwood LA, Cross MJ. The intercondylar shelf and the anterior cruciate ligament. Am J Sports Med 1977;5:171–176. 35. Palmer I. On the injuries to the ligaments to the knee joint. A clinical study. Acta Chir Scand 1938;53(suppl). 36. Schickendantz M, Weiker G. The predictive value of radiographs in the evaluation of unilateral and bilateral anterior cruciate ligament injuries. Am J Sports Med 1993;21:110–113. 37. Shelbourne KD, Davis TJ, Klootwyk TE. The relationship between intercondylar notch width of the femur and the incidence of anterior cruciate ligament tears: a prospective study. Am J Sports Med 1998;26:402–408. 38. Souryal TO, Freeman TR. Intercondylar notch size and anterior cruciate ligament injuries in athletes: a prospective study. Am J Sports Med 1993;21:535–539. 39. Anderson AF, Lipscomb AB, Liudahl KJ, et al. Analysis of the intercondylar notch by computed tomography. Am J Sports Med 1987;15:547–552. 40. Houseworth S, Mauro V, Mellon B, et al. The intercondylar notch in acute tears of the anterior cruciate ligament: a computer graphics study. Am J Sports Med 1987;15:221–224. 41. Anderson AF, Dome DC, Gautam S, et al. Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate ligament tear rates. Am J Sports Med 2001;29:58–66. 41a. Tillman MD, Smith KR, Bauer JA, et al. Differences in three intercondylar notch geometry indices between males and females: a cadaver study. Knee 2002;9:41–46. 42. Charlton WP, St John TA, Ciccotti MG, et al. Differences in femoral notch anatomy between men and women: a magnetic resonance imaging study. Am J Sports Med 2002;30:329–333. 43. Chandrashekar N, Slauterbeck J, Hashemi J. Sex-based differences in the anthropometric characteristics of the anterior cruciate ligament and its relation to intercondylar notch geometry. Am J Sports Med 2005;33:1492–1498. 44. Muneta T, Takakuda K, Yamamoto H. Intercondylar notch width and its relation to the configuration and cross-sectional area of the anterior cruciate ligament. Am J Sports Med 1997;25:69–72. 45. Rizzo M, Holler SB, Bassett FH. Comparison of males' and females' ratios of anterior-cruciate-ligament width to femoralintercondylar-notch width: a cadaveric study. Am J Orthop 2001;30:660–664. 46. Arendt E, Agel J, Dick R. Anterior cruciate ligament injury patterns among collegiate men and women. J Athletic Tr 1999;34:86–92. 47. Myklebust G, Maehlum S, Holm I, et al. A prospective cohort study of anterior cruciate ligament injuries in elite Norwegian team handball. Scand J Med Sci Sports 1998;8:149–153. 48. Wojtys EM, Huston LJ, Lindenfeld TN, et al. Association between the menstrual cycle and anterior cruciate ligament injuries in female athletes. Am J Sports Med 1998;26:614–619. 49. Beynnon BD, Johnson RJ, Braun S, et al. The relationship between menstrual cycle phase and anterior cruciate ligament injury: a casecontrol study of recreational alpine skiers. Am J Sports Med 2006;34:757–764.

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50. Slauterbeck JR, Fuzie SF, Smith MP, et al. The menstrual cycle, sex hormones, and anterior cruciate ligament injury. J Athl Train 2002;37:275–278. 51. Wojtys EM, Huston LJ, Boynton MD, et al. The effect of the menstrual cycle on anterior cruciate ligament injuries in women as determined by hormone levels. Am J Sports Med 2002;30:182–188. 52. Wojtys EM, Huston LJ. The effect of the female menstrual cycle on lower extremity neuromuscular performance and anterior knee laxity. American Academy of Orthopaedic Surgeons, Anaheim, CA, 1999. 53. Belanger MJ, Moore DC, Crisco JJ, III, et al. Knee laxity does not vary with the menstrual cycle, before or after exercise. Am J Sports Med 2004;32:1150–1157. 54. Karageanes SJ, Blackburn K, Vangelos ZA. The association of the menstrual cycle with the laxity of the anterior cruciate ligament in adolescent female athletes. Clin J Sport Med 2000;10:162–168. 55. Van Lunen BL, Roberts J, Branch JD, et al. Association of menstrualcycle hormone changes with ACL laxity measurements. J Athl Train 2003;38:298–303. 56. Heitz NA. Hormonal changes throughout the menstrual cycle and increased anterior cruciate ligament laxity in females. J Athl Train 1999;343:144–149. 57. Deie M, Sakamaki Y, Sumen Y, et al. Anterior knee laxity in young women varies with their menstrual cycle. Int Orthop 2002;26:154–156. 58. Shultz SJ, Kirk SE, Johnson ML, et al. Relationship between sex hormones and anterior knee laxity across the menstrual cycle. Med Sci Sports Exer 2004;36:1165–1174. 59. Grana W, Moretz J. Ligamentous laxity in secondary school athletes. J Am Med Assoc 1978;240:1975–1976. 60. Kalenak A, Morehouse C. Knee stability and knee ligament injuries. J Am Med Assoc 1975;234:1143–1145. 61. Moretz J, Walters R, Smith L. Flexibility as a prediction of knee injuries in college football players. PSM 1982;10:93–97. 62. Steiner M, Grana W, Chillag K, et al. The effect of exercise on anterior-posterior knee laxity. Am J Sports Med 1986;14:24–29. 63. Liu S, Al-Shakin R, Panossian V, et al. Primary immunolocalization of estrogen progesterone target cells in the human anterior cruciate ligament. J Ortho Res 1996;14:526–533. 64. Lovering RM, Romani WA. Effect of testosterone on the female anterior cruciate ligament. Am J Physiol Regul Integr Comp Physiol 2005;289:R15–R22. 65. Liu SH, Al-Shaikh RA, Panossian V, et al. Estrogen affects the cellular metabolism of the anterior cruciate ligament: a potential explanation for female athletic injury. Am J Sports Med 1997;25:704–709. 66. Slauterbeck JR, Clevenger C, Lundberg W, et al. Estrogen level alters the failure load of the rabbit anterior cruciate ligament. J Orthop Res 1999;17:405–408. 67. Seneviratne AE, Williams RJ, Rodeo SA, et al. The effect of estrogen on ovine anterior cruciate ligament fibroblasts: cell proliferation and collagen synthesis. Am J Sports Med 2004;32:1613–1618. 68. Strickland SM, Belknap TW, Turner SA, et al. Lack of hormonal influences on mechanical properties of sheep knee ligaments. Am J Sports Med 2003;31:210–215. 69. Arendt E, Agel J, Dick R. Profile of the ACL injured athlete. A pilot study. In Griffin LY (ed): Prevention of noncontact ACL injuries, Rosemont, IL, 2001, American Academy of Orthopaedic Surgeons, pp 77–86. 70. Posthuma BW, Bass MJ, Bull SB, et al. Detecting changes in function ability in women with premenstrual syndrome. Am J Obstet Gynecol 1987;15:275–278. 71. Zimmerman E, Parlee MB. Behavioral changes associated with the menstrual cycle: an experimental investigation. J Appl Sociol Psychol 1973;3:335–344. 72. Janse de Jonge XA. Effects of the menstrual cycle on exercise performance. Sports Med 2003;33:833–851. 73. Lebrun CM, Rumball JS. Relationship between athletic performance and menstrual cycle. Curr Womens Health Rep 2001;1:232–240.

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury 74. Materson G. The impact of menstrual phases on anaerobic power performance in collegiate women. J Strength Cond Res 1999;13:325–329. 75. Griffin LY, Albohm MJ, Arendt EA, et al. Understanding and preventing non-contact ACL injuries: a review of the Hunt Valley II Meeting, January 2005. Am J Sports Med 2006;34:1512–1532. 76. Boden BP, Dean GS, Feagin JA. Mechanism of anterior cruciate ligament injury. Orthopedics 2000;23:573–578. 77. Malone TR. Relationship of gender in anterior cruciate ligament (ACL) injuries of NCAA division I basketball players. J South Orthop Assoc 1992;2:36–39. 78. Myklebust G, Makhlum S, Emgebretsen L, et al. Registration of cruciate ligament injuries in Norwegian top level team handball. A prospective study covering two seasons. Scand J Med Sci Sports 1997;7:289–292. 79. Dufek JS, Bates BT. The evaluation and prediction of impact forces during landings. Med Sci Sports Exerc 1990;22:370–377. 80. Ferretti A, Papandrea P, Conteduca F, et al. Knee ligament injuries in volleyball players. Am J Sports Med 1992;20:203–207. 81. Griffis D, Vequist S, Yearout K, et al. Injury prevention of the anterior cruciate ligament. Abstract at the American Orthopaedic Society for Sports Medicine 15th Annual Meeting, No. 13, Traverse City, MI, 1989. 82. Markolf KL, Burchfield DM, Shapiro MM, et al. Combined kneeloading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13:930–935. 83. Markolf K, Gorek J, Kalzo M, et al. Direct measurement of resistant forces in the anterior cruciate ligament. J Bone Joint Surg Am 1990;72:557–567. 84. Ettlinger C, Johnson R, Shealy J. A method to help reduce the risk of serious knee sprains incurred in alpine skiing. Am J Sports Med 1995;23:531–537. 85. Johnson RJ. The ACL injury in female skiers. In Griffin LY (ed): Prevention of noncontact ACL injuries, Rosemont, IL, 2001, American Academy of Orthopaedic Surgeons, pp. 107–112. 85a. Garrett WE Jr. Non-contact ACL injuries in female athletes: risk factors and biomechanical considerations. Instructional Course Lecture Series, 78th Annual American Academy of Orthopaedic Surgeons Meeting. Feb 9, 2003, New Orleans, LA. 86. DeMorat G, Weindhold P, Blackburn T, et al. Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury. Am J Sports Med 2004;32:477–483. 87. Markolf KL, Graff-Radford A, Amstutz HC. In vivo knee stability. A quantitative assessment using an instrumented clinical testing apparatus. J Bone Joint Surg Am 1978;60:664–674. 88. Bryant JT, Cooke TD. Standardized biomechanical measurement for varus-valgus stiffness and rotation in normal knees. J Orthop Res 1988;6:863–870. 89. Such CH, Unsworth A, Wright V, et al. Quantitative study of stiffness in the knee joint. Ann Rheum Dis 1975;34:286–291. 90. Wojtys EM, Ashton-Miller JA, Huston LJ, et al. A gender-related difference in the contribution of the knee musculature to sagittal-plane shear stiffness in subjects with similar knee laxity. J Bone Joint Surg Am 2002;84A:10–16. 91. Huston LJ, Wojtys EM. Neuromuscular performance characteristics in elite female athletes. Am J Sports Med 1996;261–267. 92. Chappell JD, Yu B, Kirkendall DT, et al. A comparison of knee kinetics between male and female recreational athletes in stop-jump task. Am J Sports Med 2002;30:261–267.

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93. Colby SM, Francisco A, Kirkendall DT. Electromyographic and kinematic analysis of cutting maneuvers. Implications for anterior cruciate ligament injury. Am J Sports Med 2000;28:1234–1240. 94. Decker MJ, Torry MR, Wyland DJ, et al. Gender differences in lower extremity kinematics, kinetics, and energy absorption during landing. Clin Biomech (Bristol, Avon) 2003;18:662–669. 95. Huston LJ, Vibert B, Ashton-Miller JA, et al. Gender differences in knee angle when landing from a drop-jump. Am J Knee Surg 2001;14:215–219. 96. Malinzak RA, Colby SM, Kirkendall DT, et al. A comparison of knee joint motion patterns between men and women in selected athletic tasks. Clin Biomech 2001;16:438–445. 97. Teitz CC. Video analysis of ACL injuries. In Griffin LY (ed): Prevention of noncontact ACL injuries. Rosemont, IL, 2001, American Academy of Orthopaedic Surgeons, pp 93–96. 98. Yu B, McClure SB, Onate JA, et al. Age and gender effects on knee motion patterns of youth soccer players in a stop-jump task. Am J Sports Med 2005;33:1356–1364. 99. Hewett TE, Stroupe AL, Nance TA, et al. Plyometric training in female athletes: decreased impact forces and increased hamstring torques. Am J Sports Med 1996;24:765–773. 100. Fagenbaum R, Darling WG. Jump landing strategies in male and female college athletes and the implications of such strategies for anterior cruciate ligament injury. Am J Sports Med 2003;31:233–240. 101. Hewett TE, Myer GD, Ford KR. Decrease in neuromuscular control about the knee with maturation in female athletes. J Bone Joint Surg Am 2004;86:1601–1608. 102. McLean SG, Walker K, Ford KR, et al. Evaluation of a two dimensional analysis method as a screening and evaluation tool for anterior cruciate ligament injury. Br J Sports Med 2005;39:355–362. 103. McLean SG, Huang X, Su A, et al. Sagittal plane biomechanics cannot injure the ACL during sidestep cutting. Clin Biomech (Bristol, Avon) 2004;19:828–838. 104. McLean SG, Lipfert SW, van den Bogert AJ. Effect of gender and defensive opponent on the biomechanics of sidestep cutting. Med Sci Sports Exerc 2004a;36:1008–1016. 105. Pollard CD, Davis IM, Hamill J. Influence of gender on hip and knee mechanics during a randomly cued cutting maneuver. Clin Biomech (Bristol, Avon) 2004;19:1022–1031. 106. Hewett TE, Myer GD, Ford KR. Anterior cruciate ligament injuries in female athletes. Part 1: mechanisms and risk factors. Am J Sports Med 2006;34:299–311. 107. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med 2005;33:492–501. 108. Kibler WB, Livingston B. Closed-chain rehabilitation for upper and lower extremities. J Am Acad Orthop Surg 2001;9:412–421. 109. Ford KR, Myer GD, Hewett TE. Valgus knee motion during landing in high school female and male basketball players. Med Sci Sports Exerc 2003;35:1745–1750. 110. Harner C, Paulos L, Greenwald A, et al. Detailed analysis of patients with bilateral anterior cruciate ligament injuries. Am J Sports Med 1994;22:37–43. 111. Flynn RK, Pedersen CL, Birmingham TB, et al. The familial predisposition toward tearing the anterior cruciate ligament: a case control study. Am J Sports Med 2005;33:23–28. 112. Souryal TO, Moore HA, Evans JP. Bilaterality in anterior cruciate ligament injuries: associated intercondylar notch stenosis. Am J Sports Med 1988;5:449–454.

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4

CHAPTER

Chadwick C. Prodromos Yung Han Julie Rogowski Brian T. Joyce Kelvin Shi

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs INTRODUCTION Although many studies have examined the incidence of anterior cruciate ligament (ACL) tears for given populations, an overall understanding of the real incidences is difficult to ascertain due to the breadth of the data and the disparate manner in which it is reported. The overall number of ACL tears appears to be increasing. This is caused in part by the increased participation of females in high-risk sports, as females clearly have an overall higher incidence of ACL tears than males. This realization has spawned the creation of training programs designed to decrease the incidence of ACL tears in females. The increase in ACL tears is also fueled by the increase in sports participation, from seasonal to yearlong, by athletes of both genders. This results in an increased number of exposures per year above that which was present for single-sport athletes in the past. Some sports appear to have higher risks of ACL tears than others, but these differences have not been well understood. Knowing the relative and absolute risks of ACL tear as a function of these parameters serves to focus attention on preventive strategies, where it is most needed. It also allows athletes and parents to understand the risks of participation in various sports.

PURPOSE Our purpose was to acquire and review all of the relevant peer-reviewed published data on the

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incidence of ACL tears for the purpose of comparing the incidence of ACL tears in the following ways: 1 Among sports 2 Between females and males 3 Between those who have completed a program to decrease the incidence of ACL tears and those who have not

METHODS A computerized search of all papers in the peerreviewed literature that had a possibility of dealing with the incidence of ACL tears was performed using a variety of indexing terms. Searches were then carried out by individual sports. This produced 793 articles that had some relation to knee or ACL injuries. These articles were reviewed, and bibliographies were cross-referenced for other papers, which were also reviewed for the purpose of identifying studies that had actual numerical incidences of complete ACL tears; this eliminated the overwhelming majority of papers. However, 33 papers were found that did have such quantitative data, and they form the basis for this chapter. Of these 33 papers, 25 had data that either used, or could be converted into, the preferred ACL injury incidence reporting method, namely: “ACL tears/1000 exposures.” An exposure is defined as either a practice or a game. These studies are listed in Table 4-1. They are divided by sport and then subdivided by level of competition, gender, and

TABLE 4-1 ACL Tear Rate by Sport, Gender, and Injury Training* Sport

Basketball

Level

Subgroup

Professional {

WNBA

Author

Male and

ACL

Female

Tears

Exposures

ACL

0.20

Trojian22

9

45,036

0.08

332

4,334,807

3.50

514

1,797,730

0.08

168

2,092,224

3.63

0.30

275

925,501

0.08

84

1,046,669

1,375,974

0.30

189

639,898

0.07

49

736,076

4.29

6

21,734

0.48

5

10,452

0.09

1

11,282

5.33

0.14

5

35,226

0.00

0

1360

0.15

5

33,866

0.00

0.19

11

56,960

0.42

5

11,812

0.13

6

45,148

3.23

0.13

11

84,341.66

0.09

11

120,751

0.02

4

169,885

4.50

0.11

2

18,076

0.48

3

6302

0.29

3

10,370

0.42

2

4757

Faude

0.65

11

16,830

Soderman21a

0.18

4.0

22,134

0.04

1.0

27,846

0.17

1393

8,068,016

0.28

1061

NCAA

Agel13

0.18

682

3,889,954

0.29

Collegiate

Harmon36

0.18

359

1,972,170

NCAA

Arendt

14

0.17

238

Naval: collegiate

Gwinn17

0.28

Naval: intramural

Gwinn17

Naval: all levels

Gwinn17 Gomez25 Messina24

0.05

15

290,636

Pfeiffer19

Trained Hewett

21

Trained 20

league Adults

Competitive: trained

Adults

Competitive: untrained

Adults

{

College

Recreational

Bjordal18

0.07

131

1,837,455.83

NCAA

Mihata15

0.21

1295

6,283,785

0.32

871

2,736,615

0.12

424

3,547,170

2.67

NCAA

Agel13

0.21

586

2,840,568

0.33

394

1,208,994

0.12

192

1,631,574

2.75 continued

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

3,733,209

Mihata15

German national

Female/Male

70,185

NCAA

Adults

Exposures

15

College

{

ACL

0.21

Lombardo

Untrained

Male

Tears

23

NBA

Untrained

Exposures

Tears

Professional

High school

Soccer

Female

4

29

30 Sport

Level

Subgroup

High school

Author

Male and

ACL

Female

Tears

Exposures

ACL

Exposures

Male

Tears

ACL

Exposures

Female/Male

Tears

Collegiate

Harmon36

0.20

317

1,605,004

0.32

194

604,430

0.12

123

1,000,574

NCAA

Arendt14

0.19

178

934,971

0.31

97

308,748

0.13

81

626,223

2.38

Naval: collegiate

Gwinn17

0.32

6

18,916

0.77

5

6508

0.08

1

12,408

9.63

Naval: intramural

Gwinn17

0.46

12

26,204

2.70

2

742

0.39

10

25,462

6.92

Naval: all levels

Gwinn17

0.40

18

45,120

0.97

7

7250

0.29

11

37,870

3.34

Untrained

Mandelbaum16

0.49

67

137,448

0.09

6

67,860

0.11

1

9357

0.00

0

5913

0.22

2

9017

0.00

0

4517

Trained Untrained

Pfeiffer19

Trained Untrained

Hewett21

Trained Alpine

Female

Deibert12

0.40

1448

3,641,041

Warme11

0.63

1615

2,550,000

Employees

Oates9

0.02

19

1,196,496

Employees

Viola10

0.04

31

726,836

0.04

10

227,766

0.04

21

499,070

1.0

0.18

315

1,783,903

0.18

146

799,611

0.17

169

984,292

1.06

All ages

skiing

General population

Adults

General population

Lacrosse

College

NCAA

Mihata15

American

Adults

Professional

Scranton37

0.07

61

895,908

DeLee28

0.11

37

331,561

0.11

5

43,891

0.24

5

20,462.67

football High school} Handball

Adults||

Elite athletes

Myklebust31

Adults

Recreational

Seil32

Adults}

Untrained

Petersen30

Trained Young

Competitive

Wedderkopp38

0.33

28

84,690

0.56

23

40,799

0.86

5

5815

1.60

1

625

0.09

4

42,442.42

5.09

#

adults

continued

Anterior Cruciate Ligament Injury

TABLE 4-1 ACL Tear Rate by Sport, Gender, and Injury Training*—Cont'd

TABLE 4-1 ACL Tear Rate by Sport, Gender, and Injury Training*—Cont'd Sport

Level

Australian football

Subgroup

Adults

Professional:

{

Volleyball

Male and

ACL

Female

Tears

Exposures

College

High school

Collegiate

Levy29

Naval: collegiate

Gwinn17

Untrained

Pfeiffer19

0.22

7

31,263

Hewett

21

83

100,820

0.36

21

58,296

0.35

3

8475

0.18

4

22,788

1.94

0.00

0

11,229

0.00

0

5739

0.00

0

3751

0.00

0

7938

0.25

3

11,888

0.77

1

1,306

0.19

2

10,582

4.05

Indoor

All ages**

General

Lindenfeld26

2.78

10

3600

5.21

8

1536

0.97

2

2064

5.37

5.30

1

190

5.0

2

600

1.04

population {{

General

Putukian27

Games only. Assumed 1.5 games and 2.25 practices.

Data was converted by information given by the author. Assumed 2.25 practices. Per hour, we assumed an exposure for team handball to be 2 hours combined practices and games.

Assumed season: 1 year; games; 50 minutes. Games only: games were 45 minutes, so total player hours were divided by 0.75.

{{

0.82

Gwinn

*Incidences are expressed as complete ACL tears/1000 exposures.

**

Female/Male

Naval: collegiate

17

population

#

Exposures

College

All ages

}

ACL

Wrestling

soccer

||

Male

Tears

Orchard33

Trained

}

Exposures

2001

Untrained

{

ACL Tears

Trained

{

Female

Games only: exposure is player hours then multiplied the incidence by 1000.

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

Rugby

Author

4

31

Anterior Cruciate Ligament Injury whether an ACL injury-reduction training program had been applied. The ratio of injury of females versus males is also listed for studies in which there were cohorts for both genders. These data form the basis for the analyses present in this chapter. Table 4-2 aggregates like subgroups from Table 4-1 and provides mean injury rates weighted according to the number of exposures. Table 4-3 lists the remaining studies, which use methods other than “tears/1000 exposures”1–8. Table 4-4 aggregates the like populations from studies that compared incidences by gender. Table 4-5 lists all the studies that involved training regimens designed to reduce ACL tear incidence.

EXPOSURES In all of these studies it is important to remain cognizant of the number of exposures in the given study. The variance in the number of exposure between the studies is very large. The largest study has more than 8 million exposures and the smallest has only 600, a difference of more than 10,000 to 1 in the statistical power of the studies. These differences are so important that we have highlighted all the studies with exposures of more than 100,000 to make it easier for the reader to recognize those incidence studies of greatest statistical power.

DATA CONVERSIONS A number of studies report their incidence by dividing the number of ACL tears by hours of participation instead of practices. In these studies the hourly incidence was therefore used to calculate an incidence per 1000 exposures by converting hours to practices or games and adjusting the incidence accordingly. Doing so allowed these series to be used in the comparative analysis with the other studies, which used the tear per exposure methodology. Without this method, a large number of useful studies would have been lost from the analysis. If an exact practice length was not listed, we assumed a practice length of 2.25 hours. In the study by DeLee,28 the data were presented in tears per hour, but exact data were given on number of practices and games and their lengths, so the data could be directly transformed into tears per 1000 exposures.

INDIVIDUAL SPORTS Alpine Skiing The alpine skiing data are notable for the large disparity in incidence between ski lodge employees, who are assumed to be expert skiers, and recreational skiers. The two studies of ski lodge employees by Oates and Viola show rates of 32

0.02 and 0.04, respectively.9,10 The two general population studies by Warme and Deibert show tenfold higher rates of 0.63 and 0.40, respectively.11,12 Although the rate for the expert skiers is the lowest for any of the high-risk sports studied, the rate for the recreational skiers is overall one of the highest (P < 0.001). It is remarkable that this huge disparity is produced by two independent studies in each group, each with a very large number of exposures. These observations are thus of high reliability and statistical power. The lower risk among the expert skiers is presumably a combination of increased skill and increased fitness in this group. The expert group is also remarkable for being one of only two cohorts for which the rate of injury is the same for males and females. The lack of a gender difference in the large study by Viola10 is also remarkable. Aside from lacrosse, alpine skiing is the only sport studied with a large enough number of exposures to generate reliable numbers to find this lack of a gender difference.

Soccer The soccer data are dominated by the three extremely large studies of Mihata, Agel, and Arendt.13–21 These data are remarkable for their amazing similarity. The female rates in the Mihata, Agel, and Arendt studies are 0.32, 0.33, and 0.31, respectively; the male rates are 0.12, 0.12, and 0.13, respectively. The female–male ratios are all also in the 2.5 to 1 range. The overall female to male difference was highly significant (P < 0.0001). Soccer is also notable in that in all three high school studies with ACL injury-reduction training program cohorts, the programs were apparently successful. (These studies were carried out only in females.) In other words, the trained athletes had significantly lower ACL injury rates (P ¼ 0.0001) than the untrained athletes. These data are dominated by the landmark Mandelbaum et al study,16 which showed a 24% reduction in ACL tear incidence. It should be noted that the one adult study showed no reduction in ACL tear incidence with training.21a

Basketball As was the case with soccer, the basketball rates are dominated by the three large studies of Mihata, Agel, and Arendt.* Also similar to soccer, the basketball numbers are amazingly similar among the studies. The female rates are 0.28, 0.29, and 0.30. The male rates are 0.08, 0.08, and 0.07. The female to male ratios are 3.5, 3.6, and 4.2. The overall difference in rate between females and males was *References 13–15, 17, 19, 21–25.

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

4

TABLE 4-2 Weighted Means for Groups* Sport

Basketball

Level

Male and

ACL

Female

Tears

Exposures

Female ACL

Exposures

Male ACL

Tears

Exposures

Tears

Exposures

0.20

9

45,036

0.21

15

70,185

0.29

2049

7,119,962

0.08

645

8,300,072

0.10

27

233,538.66

0.02

4

169,885

High school: trained

0.45

5

11,069

German National

0.65

11

16,830

0.04

1

27,846

0.18

4

22,134

0.32

1570

4,873,287

0.45

70

155,822

0.08

6.0

78,290

Professional Collegiate

0.17

2694

15,420,034

High school:

Total

untrained

Soccer

15,949,747.66

League Adult competitive: untrained Adult competitive: trained Adult recreational

0.07

2412

11,754,568

Collegiate

0.21

2412

11,754,568

High school:

0.12

842

6,881,281

untrained High school: trained

13,892,945.83 Alpine skiing

Employees

0.03

50

1,923,332

General population

0.49

3063

6,191,041

0.04

10

227,766

0.04

21

499,070

8,114,373 Lacrosse

Collegiate

0.18

315

1,783,903

0.18

146

799,611

0.17

169

984,292 1,783,903

American football

Professional

0.07

61

895,908

High school

0.11

37

331,561 1,227,469

Handball

Elite athletes

0.33

28

84,690

Adult recreational:

0.56

23

40,799

0.11

5

43,891

0.86

5

5815

0.24

5

20,462.67

1.6

1

625

0.09

4

42,442.42

untrained Adult recreational: trained Young adults

154,035.09 Australian

0.82

Professional

83

100,820

football Rugby

100,820 Collegiate

0.22

7

31,263

0.36

24

66,771

0.18

4

22,788 89,559 continued

33

Anterior Cruciate Ligament Injury TABLE 4-2 Weighted Means for Groups*—Cont'd Sport

Volleyball

Level

Male and

ACL

Female

Tears

Exposures

Female ACL

Exposures

Male ACL

Tears

Exposures

Tears

High school: untrained

0.00

0.00

14,980

High school: trained

0.00

0.00

13,677

Total Exposures

28,657 Wrestling

Collegiate

0.25

3

11,888

0.77

1

1306

0.19

2

10,582 11,888

Indoor

General population

2.78

14

3600

5.21

9

7126

1.88

5

2664

soccer 4390 *Incidences are expressed as complete ACL tears/1000 exposures.

highly significant (P < 0.0001). Interestingly, and unlike the case with soccer, the two studies that included a cohort in which athletes had completed a program to diminish the ACL tear incidence showed no reduction in ACL tear rate as a result of training. In fact, the trained athletes in both studies showed increased ACL tear rates versus the untrained athletes, although this difference was not significant.

Indoor Soccer The two studies of indoor soccer are included for the sake of completeness, but with only about 3600 total exposures, they have negligible statistical power by comparison to the more than 10 million soccer exposures by the three large studies cited earlier for outdoor soccer.27,28 Thus the very high female incidence of 5.2 tears per 1000 exposures, more than 10 times the outdoor rate, should be interpreted with caution, although the difference between females and males was statistically significant (P ¼ 0.04). Nonetheless it is of interest that two separate studies arrived at almost identically high rates. If these increased rates were real, there would be two obvious potential causes: first, the fact that this study included only games, not practices, implying a higher risk with competition. Second, the fact that indoor soccer is played on artificial turf, whereas outdoor soccer is played on grass, may upwardly influence the injury rate.

Volleyball The two volleyball studies have only 28,000 exposures, again too small to make reliable incidence conclusions.19,21 However, it is remarkable that no ACL tears were recorded in either study. Basketball and soccer are often included with volleyball as high-risk sports for females. The rates of the six cohorts for basketball and soccer from each of the three large cited studies are all clustered between 0.28 and 0.33. 34

If the average rate of 0.30 is applied to the 28,000 volleyball exposures, about 9 ACL tears would be expected. The fact that none were recorded may support a lower incidence of ACL tears in volleyball than in soccer and basketball.

Football The one large football study, all in high school males, produced an injury rate of 0.11.29 This is very similar to the male rate found in college soccer (0.12) and basketball (0.08). With more than 331,000 exposures, this study is of high statistical power.

Rugby The 0.35 and 0.36 rates for women and the 0.18 rate for men from the two published studies are very similar to the 0.32 rate for women and 0.12 rate for men found in soccer.17,30 This is not unexpected given the similarities of the sports, which involve running and pivoting on a grass surface. It is of interest that the higher level of contact in rugby did not produce a higher ACL tear rate. The 89,000 total exposures are a significant number, although far less than the soccer exposure numbers. Further supporting the validity of the data, however, is the fact that two separate rugby studies produced almost identical ACL tear incidences.

Wrestling With just under 12,000 exposures, the one wrestling study is of low power.17 It showed a rate of 0.77 in females and 0.19 in males.

Lacrosse There is one published study with usable data for our analysis.15 The 0.17 rate of ACL tear for men is similar to that

TABLE 4-3 Studies not Expressed in ACL Tears/1000 Exposures Basketball Basketball

Basketball Soccer

Handball

Handball

Handball

Handball

American

American

Australian

Australian

Football

Football

Football

Football

Deitch6

Deitch6

Deitch6

Heidt4

Myklebust31

Myklebust31

Myklebust31

Myklebust31

Lambson7

Powell1

Orchard8

Orchard8

Year

2006

2006

2006

2000

2003

1997

1997

1997

1996

1992

2001

1999

NBA &

NBA

WNBA

High school

Amateur/semi-

Amateur/semi-

Amateur/semi-

Amateur/semi-

High school NFL

AFL

AFL

professional

professional

professional

professional

1998–1999;

1989–1991

1989–1991

1989–1991

1989–1991,

1980–

1992–2000

1992–1998

3 years

1989, 10

ACLR

ACL

required

required

M

M

M

114

74

78

Level

WNBA Details

1996–2002

1997–2002 14- to 18-

(minus strike- seasons

year-old

females, upper

seasons; two

seasons; two

seasons; two

shortened

females (1

division,

seasons, three

seasons, three

seasons, three

1998–1999)

year,

Norway, one

upper divisions in

upper divisions in

upper divisions in

2 seasons)

season

Norway

Norway

Norway

Arthroscopy

Arthroscopy

Arthroscopy

Not specified Arthroscopy

seasons

Criteria for

Did not

Did not

Did not

ACL injury

specify

specify

specify

Arthroscopy

Sex

M&F

M

F

F

F

M&F

M

F

M

Total ACL

36

22

14

8

29

87

33

54

42

19

10

9

23

29

Practice ACL 17

12

5

6

13

1145

702

443

258

942

3392

1696

1696

3119

6

6

6

1

1

2

2

2

3

definition

injury Game ACL injury

injury Total

2238

number of participants Years

9

7 continued

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

Author

4

35

36 Basketball Basketball

Basketball Soccer

Total player

516

Handball

942

Handball

6784

Handball

3392

Handball

American

American

Australian

Australian

Football

Football

Football

Football

1757

2280

42.1

34.8

3392

seasons Total player

15,447

123,156

game hours Total player

193,389

practice hours Total player

208,836

game and practice hours Number of games Total player

93,400

70,420

22,980

15,547

123,156

31.4

31.3

31.6

31.0

30.8

25.6

19.5

31.8

13.5

5.2

5.2

5.3

31.0

30.8

12.8

9.7

15.9

4.5

games ACL injury/ 1000 players ACL injury/ 1000 player years ACL injury/ 1000 games ACL injury/

1.49

0.93

5.0

1000 player game hours continued

Anterior Cruciate Ligament Injury

TABLE 4-3 Studies not Expressed in ACL Tears/1000 Exposures—Cont'd

TABLE 4-3 Studies not Expressed in ACL Tears/1000 Exposures—Cont'd Basketball Basketball

Basketball Soccer

Handball

Handball

Handball

American

American

Australian

Australian

Football

Football

Football

Football

0.031

34.2

1000 player practice hours ACL injury/

0.14

1000 player game and practice hours ACL injury/

0.20

0.14

0.39

1.49

0.93

1000 player games ACL injury/ 1000 player seasons

15.5

30.8

12.8

9.7

15.9

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

ACL injury/

Handball

4

37

Anterior Cruciate Ligament Injury TABLE 4-4 Ratios of Female to Male ACL Tear Rates* Sport

Basketball

Level

College

Subgroup

Author

Female ACL

Exposures Male ACL

Tear

Tear

Exposures Female/

NCAA

Mihata15

0.28

1061

3,733,209

0.08

332

4,334,807

3.50

NCAA

Agel13

0.29

514

1,797,730

0.08

168

2,092,224

3.63

36

Collegiate

Harmon

0.30

275

925,501

0.08

84

1,046,669

3.75

NCAA

Arendt14

0.30

189

639,898

0.07

49

736,076

4.29

Naval: collegiate

17

Gwinn

0.48

5

10,452

0.09

1

11,282

5.33

Naval: intramural

Gwinn17

0.00

0

1360

0.15

5

33,866

0.00

17

0.42

5

11,812

0.13

6

45,148

3.23

Naval: all levels

Gwinn Mean

0.29 24

0.08 11

120,751

0.02

3.63

Messina

0.09

Mean

0.28

NCAA

Mihata15

0.32

871

2,736,615

0.12

424

3,547,170

2.67

NCAA

Agel13

0.33

394

1,208,994

0.12

192

1,631,574

2.75

Collegiate

Harmon36

0.32

194

604,430

0.12

123

1,000,574

2.67

NCAA

Arendt14

0.31

97

308,748

0.13

81

626,223

2.38

Naval: collegiate

Gwinn17

0.77

5

6508

0.08

1

12,408

9.63

Naval: intramural

Gwinn17

2.70

2

742

0.39

10

25,462

6.92

17

Gwinn

0.97

7

7250

0.29

11

37,870

3.34

Mean

0.32

High

P Value

Male

4

169,885

4.50

school

Soccer

College

Naval: all levels

10

Alpine skiing Employees Lacrosse

Handball

College

Adults

NCAA

Elite athletes

0.91

0.04

21

499,070

1.00

Mihata15

0.18

148

799,611

0.17

169

984,292

1.06

Mean

0.18

1.05

0.59

23

40,799

0.11

5

43,891

5.09

<0.0001

0.35

3

8475

0.18

4

22,788

1.94

0.36

0.77

1

1306

0.19

2

10,582

4.05

0.25

Lindenfeld

5.21

8

1536

0.97

2

2064

5.37

Putukian27

5.20

1

190

5.00

3

600

1.04

Mean

5.21

Myklebust31 0.56 17

Gwinn

Wrestling

College

Naval: collegiate

Gwinn17

General

<0.0001

227,766

0.17

<0.0001

2.67

10

Naval: collegiate

All ages

0.12

0.04

College

soccer

3.50

Viola

Rugby

Indoor

0.08

26

population General population 1.88

2.77

0.04

*Incidences are expressed as complete ACL tears/1000 exposures.

of soccer, rugby, and basketball. The female rate of 0.18, however, is substantially lower than the female rates for these three sports. With 1,783,903 exposures, this study is of high statistical power. Lacrosse stands as the only sport aside from alpine skiing for which the rates for males and females are roughly the same. There is no obvious 38

explanation. The argument has been made that the carrying of the stick is ACL tear protective and may be at least part of the reason for the lower injury rate in females. However, if this were true there would be no obvious explanation for the fact that such an effect does not serve to lower the rate in males compared with other similar sports.

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs

4

TABLE 4-5 Effect of ACL Reduction Training Program on Tear Rate* Sport

Level

Basketball High school

Author

Subgroup Female ACL

Exposures Subgroup Female ACL

Tear

Tear

Competitive

(T–UT)

Hewett21

Untrained

0.29

3

10,370

Trained

0.42

2

4767

13%

Pfeiffer19

Untrained

0.11

2

18,076

Trained

0.48

3

6302

37%

Mean Soccer

Exposures Change

0.18

Soderman21a

0.45

P Value

0.15

Untrained

0.04

1

27,846

Trained

0.18

4

22,134

14%

Untrained

0.22

2

9017

Trained

0.00

0

4517

–22%

Mandelbaum

Untrained

0.49

67

137,448

Trained

0.09

6

67,860

–40%

Pfeiffer19

Untrained

0.11

1

9357

Trained

0.00

0

5913

–11%

adults High school

Hewett21 16

Mean Volleyball High school

0.45

–24%

0.08

Hewett21

Untrained

0.00

0

3751

Trained

0.00

0

7938

0%

19

Untrained

0.00

0

11,229

Trained

0.00

0

5739

0%

Pfeiffer Mean

0.00

Handball The two published female cohorts both have very high incidences of 0.56 and 0.86.30,31 The two male cohorts of 0.24 and 0.11 are relatively unremarkable.31,32 The gender difference is significant (P < 0.0001).

Australian Rules Football The one large published study with usable data showed a quite high ACL tear rate of 0.82 per 1000 exposures (games only in this study).33 This is quite high in relation to other sports for males. The 100,000 exposures represent a substantial number, although not as large as some studies. It is interesting to note that the indoor soccer study, which was also a gamesonly study, also had an unusually high tear rate of 0.97. This suggests the possibility that games have a higher risk of ACL tear than practices, although there are far too little data to make this conclusion. If this is not a contributing factor, other explanations would include an intrinsically high rate for Australian Rules football or that the rate is high due to chance in this modest-sized study.

THE OVERALL RISK OF ANTERIOR CRUCIATE LIGAMENT TEAR This chapter has focused on the rate per exposure in determining ACL risk. However, the number of exposures is

0.0001

0.00

equally, if not more, important. The proliferation of club teams for high-risk sports, especially soccer, thus combines a relatively high-incidence sport with a high yearly number of exposures, leading to an overall high risk. The year-round club soccer player's ACL tear risk will be much higher than the now nearly extinct three-sport athlete of years past, many of whom would have engaged in at least one lower-risk sport such as softball, baseball, tennis, or swimming during the year. Hewett's prospective study,34 for example, found a 4.4% 1-year chance of ACL tear in girls engaged in high-risk sports. For the injury rate of about 0.3 seen in girls' basketball and soccer, a 5% yearly ACL risk would be seen after 167 yearly exposures–not an excessive number for a year-round player.1 Equipped with the incidence contained in this chapter, one need only plug in a putative number of yearly exposures to generate an approximate risk of yearly ACL tear.

FEMALE–MALE INJURY RISK RATIO The female–male ratio for the five sports for which there are reliable data is as follows: basketball, 3.5; soccer, 2.67; rugby, 2.0; lacrosse, 1.05; expert alpine skiers, 1.0. Soccer and basketball dwarf the other sports in level of participation and are the sports usually thought of when this topic is discussed. For these two sports, the increased risk versus males is overall about 3 to 1. This is obviously a higher rate of ACL tear in females versus males but is much less than the rates of 6 or even 8 to 135 that are sometimes cited. 39

Anterior Cruciate Ligament Injury

ANTERIOR CRUCIATE LIGAMENT TEARPREVENTION PROGRAMS The published data have shown ACL injury-prevention programs to be effective in high school soccer. The data in this study, however, have shown no significant benefit in other sports. In this regard, Pfeiffer et al speculate that significant benefit may require strength and possibly flexibility training in addition to landing and agility training.19

IMPLICATIONS FOR FUTURE ANTERIOR CRUCIATE LIGAMENT INJURY-REDUCTION RESEARCH The most striking finding in this study is the 16-fold reduction in alpine skiing injury rate in expert versus recreational skiers, with no difference between males and females. This, combined with the success of female ACL tear reduction programs and the lack of a difference in tear rates in lacrosse, indicates that biological differences between males and females are probably far less important than proper technique. It also squarely highlights basketball as the major sport with both the largest gender disparity, at 3.5 females to 1 male, and the only one that thus far has not proven amenable to reduction of the female rate. Additional study of technical factors contributing to female basketball ACL tears should thus be a high priority for future research.

CONCLUSIONS The following conclusions can be made: 1 Females have a roughly 3.5 times greater risk of ACL tear than males in basketball and 2.7 times greater risk in soccer– not the six to eight times increased risk sometimes cited. 2 ACL tear reduction programs have thus far only proven effective in high school soccer but not in basketball. 3 Recreational alpine skiers have a 16-fold higher incidence of tears than expert skiers. 4 Expert alpine skiers and lacrosse players are the only studied athletes in whom females do not have a higher incidence of ACL tears compared with males. 5 For males, the incidence of ACL tear is similar in football, soccer, and basketball. 6 Volleyball may be a low-risk sport, not high-risk as previously thought, for ACL tear. 7 The approximate yearly risk for ACL tear can be calculated from the data in this chapter. The risk for a 40

year-round female club soccer player would appear to be roughly 5% per year.

References 1. Powell JW, Schootman M. A multivariate risk analysis of selected playing surfaces in the national football league: 1980 to 1989. Am J Sports Med 1992;20:686–694. 2. Myklebust G, Engebretsen L, Braekken IH, et al. Prevention of anterior cruciate ligament injuries in female team handball players. A prospective intervention study over three seasons. Clin J Sport Med 2003;13:71–78. 3. Mykelbust G, Maehlum S, Engebretsen L, et al. Registration of cruciate ligament injuries in Norwegian top level team handball. A prospective study covering two seasons. Scand J Med Sci Sports 1997;7:289–292. 4. Heidt RS, Sweeterman LM, Carlonas RL, et al. Avoidance of soccer injuries with preseason conditioning. Am J Sports Med 2000;28:659–662. 5. Orchard J, Seward H, McGivern J, et al. Rainfall, evaporation and the risk of non-contact anterior cruciate ligament injury in the Australian football league. Med J Aust 1999;170:304–306. 6. Deitch JR, Starkey C, Walters SL, et al. Injury risk in professional basketball players. Am J Sports Med 2006;10:1–7. 7. Lambson RB, Barnhill BS, Higgins RW. Football cleat design and its effect on anterior cruciate ligament injuries. Am J Sports Med 1996;24:155–159. 8. Orchard J. The AFL penetrometer study: work in progress. Aust J Sci Med Sport 2001;4:220–232. 9. Oates KM, Van Eenenaam PV, Briggs K, et al. Comparative injury rates of uninjured, anterior cruciate ligament-deficient, and reconstructed knees in a skiing population. Am J Sports Med 1999;27:606–610. 10. Viola RW, Steadman JR, Mair SD, et al. Anterior cruciate ligament injury incidence among male and female professional alpine skiers. Am J Sports Med 1999;27:792–795. 11. Warme WJ, Feagin JA, King P, et al. Ski injury statistics, 1982 to 1993, Jackson Hole Ski Resort. Am J Sports Med 1995;23:597–600. 12. Deibert MC, Aronsson DD, Johnson RJ, et al. Skiing injuries in children, adolescents, and adults. J Bone Joint Surg Am 1998;80A:25–32. 13. Agel J, Arendt EA, Bershadsky B. Anterior cruciate ligament injury in national collegiate athletic association basketball and soccer. Am J Sports Med 2005;33:524–531. 14. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. Am J Sports Med 1995;23:694–701. 15. Mihata LC, Beutler AI, Boden BP. Comparing the incidence of anterior cruciate ligament injury in collegiate lacrosse, soccer, and basketball players. Am J Sports Med 2006;34:899–904. 16. Mandelbaum BR, Silvers HJ, Watanabe DS, et al. Effectiveness of a neuromuscular and proprioceptive training program in preventing the incidence of anterior cruciate ligament injuries in female athletes. Am J Sports Med 2005;33:1–7. 17. Gwinn DE, Wilckens JH, McDevitt ER, et al. The relative incidence of anterior cruciate ligament injury in men and women at the United States Naval Academy. Am J Sports Med 2000;28:98–102. 18. Bjordal JM, Arnoy F, Hannestad B, et al. Epidemiology of anterior cruciate ligament injuries in soccer. Am J Sports Med 1997;25:341–345. 19. Pfeiffer RP, Shea KG, Roberts D, et al. Lack of effect of a knee ligament injury prevention program on the incidence of noncontact anterior cruciate ligament injury. J Bone Joint Surg 2006;88:1769–1774. 20. Faude O, Junge A, Kindermann W, et al. Injuries in female soccer players. Am J Sports Med 2005;33:1694–1700. 21. Hewett TE, Lindenfeld TN, Riccobene JV, et al. The effect of neuromuscular training on the incidence of knee injury in female athletes. Am J Sports Med 1999;27:699–706.

The Incidence of Anterior Cruciate Ligament Injury as a Function of Gender, Sport, and Injury-Reduction Programs 21a. Soderman K, Werner S, Pietila T, et al. Balance board training: Prevention of traumatic injuries of the lower extremities in female soccer players? Knee Surg Sports Traumatol Arthrosc 2000;8:356–363. 22. Trojian TH, Collins S. The anterior cruciate ligament tear rate varies by race in professional women's basketball. Am J Sports Med 2006;10:1–4. 23. Lombardo S, Sethi PM, Starkey C. Intercondylar notch stenosis is not a risk factor for anterior cruciate ligament tears in professional male basketball players. Am J Sports Med 2005;33:29–34. 24. Messina DF, Farney WC, DeLee JC. The incidence of injury in Texas high school basketball. Am J Sports Med 1999;27:294–299. 25. Gomez E, DeLee JC, Farney WC. Incidence of injury in Texas girls' high school basketball. Am J Sports Med 1996;24:684–687. 26. Lindenfeld TN, Schmitt DJ, Hendy MP, et al. Incidence of injury in indoor soccer. Am J Sports Med 1994;22:364–371. 27. Putukian M, Knowles WK, Swere S, et al. Injuries in indoor soccer. Am J Sports Med 1996;24:317–322. 28. DeLee JC, Farney WC. Incidence of injury in Texas high school football. Am J Sports Med 1992;20:575–580. 29. Levy AS, Wetzler MJ, Lewars M, et al. Knee injuries in women collegiate rugby players. Am J Sports Med 1997;25:360–362. 30. Petersen W, Braun C, Bock W, et al. A controlled prospective case control study of a prevention training program in female team

31.

32. 33.

34.

35. 36. 37.

38.

4

handball players: the German experience. Arch Orthop Trauma Surg 2005;9:614–621. Myklebust G, Maehlum S, Holm I, et al. A prospective cohort study of anterior cruciate ligament injuries in elite Norwegian team handball. Scand J Med Sci Sports 1998;8:149–153. Seil R, Rupp S, Tempelhof S, et al. Sports injuries in team handball. Am J Sports Med 1998;26:681–687. Orchard J, Seward H, McGivern J, et al. Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers. Am J Sports Med 2001;29:196–200. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes. Am J Sports Med 2005;33:492–501. Toth AP, Cordasco FA. Anterior cruciate ligament injuries in the female athlete. J Gend Specif Med 2001;4:25–34. Harmon KG, Dick R. The relationship of skill level to anterior cruciate ligament injury. Clin J Sport Med 1998;8:260–265. Scranton Jr. PE, Whitesel JP, Powell JW, et al. A review of selected noncontact anterior cruciate ligament injuries in the National Football League. Foot Ankle Int 1997;18:772–776. Wedderkopp N, Kaltoft M, Lundgaard B, et al. Injuries in young female players in European team handball. Scand J Med Sci Sports 1997;7:342–347.

41

5

CHAPTER

Holly J. Silvers Robert H. Brophy Bert R. Mandelbaum

42

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete INTRODUCTION The anterior cruciate ligament (ACL) is a crucial stabilizer of the tibiofem oral joint, preventing anterior translation of the tibia on the femur during weight-bearing activities. The ACL works collectively with the posterior cruciate ligament (PCL) to stabilize the knee during dynamic movement. The PCL is attached to the posterior portion of the intercondylar eminence of the tibia and passes forward to attach to the medial condyle of the femur. The medial collateral ligament (MCL) is attached to the medial femoral condyle and the medial surface of the tibia. The lateral collateral ligament (LCL) is attached to the lateral femoral condyle and the lateral portion of the head of the fibula. The MCL and the LCL are extracapsular ligaments and provide stability to the knee joint in the frontal plane during varus and valgus loads. Since the passage of the Title IX Educational Amendment, there has been an exponential increase of female participation in sports at both the collegiate (fivefold increase over the last 30 years)1 and high-school (tenfold increase over the last 30 years)2 levels. Although participation in organized sports has many physical and psychological benefits, including decreases in obesity, hypertension, diabetes mellitus, and coronary heart disease, this increase has subsequently led to an increase in sports-related injuries.3 While identifying risk factors with regard to sports-related injury, researchers have found an increased rate of ligamentous knee injuries, especially of the ACL, in female athletes compared with their male

counterparts participating in similar activities.4–9 Among athletes in pivoting and jumping sports, adolescent females face a fourfold to sixfold increased risk of ACL injury compared with their male counterparts.6,10,11 The ACL is at risk for injury during activities that require pivoting, decelerating, or landing from a jump, such as soccer, basketball, volleyball, and team handball, as well as American football and downhill skiing.12 An estimated 80,000 to 250,000 ACL injuries occur annually in the United States alone.12,13 The highest incidence of these injuries occurs typically in young athletes between the ages of 15 to 25, which constitutes nearly 50% of all reported ACL injuries.3 Furthermore, the incidence among female athletes exceeds their male counterparts by a twofold to eightfold frequency12,13,14 Arendt and Dick examined the increased incidence of ACL injury among NCAA Division I athletes participating in basketball and soccer over a 5-year period.15 These two sports were chosen due to the fact that there is a strong similarity between the men's and women's games with regard to rules, training and development, style of play, type of playing surface, and the intensity of the competition. The injury rate was recorded and analyzed per athlete-exposure, where one practice session or game was defined as one exposure. The average ACL injury rate was 0.31 per 1000 athlete-exposures for female soccer and 0.29 per 1000 athlete-exposures for female basketball, compared with 0.13 for male soccer and 0.07 for male basketball per 1000 athlete-exposures. These epidemiological data for

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete ACL injury rates statistically signify the blatant discrepancy that exists between genders.6 ACL rupture is a severe ligamentous knee injury, leading to functional instability in the short term and degenerative joint disease in the long term. Injury to the ligament can lead to prolonged absence from both work and sport and can initiate the early onset of degenerative osteoarthritis.15,16 Although ACL reconstructive procedures are readily available, the injury is painful and costly and can be debilitating. In the United States, at least 50,000 ACL reconstructions are performed each year at a cost of about $17,000 per procedure.14,17 The direct medical cost for reconstructive surgeries alone is just under $1 billion per year ($850,000,000). This figure does not include initial treatment costs of all ACL injuries, the rehabilitation costs after reconstruction, or the costs of conservative treatment and rehabilitation of those injuries that are not repaired.18 Complete ACL injuries can lead to chronic knee pathology, including instability, secondary injury to the menisci and articular cartilage, and an early onset of osteoarthritis. Approximately 66% of all patients with complete ACL injury incur damage to the menisci and the articular cartilage of the femur, patella, and/or tibia. This injury, coupled with the risk of secondary injury, can significantly decrease the ability of patients to complete their activities of daily living and affect their quality of life. The surgical reconstruction of a ruptured ACL can significantly reduce the risk of secondary injury. Seitz et al18a noted that 65% of ACL deficient patients sustained a secondary meniscal injury within 2.5 years of the initial date of injury. Data show that despite surgical treatment of this injury, patients frequently develop posttraumatic arthritis of the knee.* Despite the most earnest efforts of orthopaedic surgeons to preserve the integrity of the knee joint during ACL reconstructive surgery, ACL reconstructed individuals continue to report with early onset of osteoarthritis. Lohmander et al completed a 12-year longitudinal study to follow up on female athletes who previously underwent ACL reconstruction after sustaining an injury while playing soccer.10 They found that 55 women (82%) had radiographic changes in their index knee and 34 (51%) fulfilled the criterion for radiographic knee osteoarthritis. The mean age for the subjects involved with this study was 31. Gillquist et al noted that the prevalence of radiographic knee gonarthrosis is significantly higher in the injured knee compared with the unaffected contralateral limb.16 The implications of this research are ominous— hence the increased need for the prevention of these injuries from occurring in the first place.7 A multidisciplinary meeting was held in Hunt Valley, Maryland, in 1999 involving biomechanists, physicians, certified athletic trainers, and physical therapists to delineate *References 4, 5, 10, 15, 16, 19–21.

5

specific risk factors thought to be directly correlated to the increased incidence of ACL injuries in the female athlete.5 The identified risk factors included anatomy, hormones, environment, and biomechanics. This meeting spurred the development of various ACL injury-prevention programs and led to increased interest and financial funding in this area of research. This group of researchers reconvened in Atlanta, Georgia, in January 2005 to reevaluate the identified risk factors and to determine what progress has been made since the inaugural meeting in 1999.

ANTERIOR CRUCIATE LIGAMENT INJURYPREVENTION STUDIES A growing number of injury-prevention programs targeted at reducing the risk of ligamentous knee injury in general and ACL injury in particular have been reported in the literature. Although a number of risk factors for ACL injury have been proposed, only the biomechanical risk factors have been examined in sufficient depth to support the design and evaluation of prevention interventions.2,14 During passive motion, tension in the ACL decreases from 0 to 35 degrees and then increases again with further flexion.5 Thus, a combination of maximal ACL tension and anterior tibial translation force occurs with quadriceps firing and joint compressive loading at or near full extension. Contraction of the hamstrings decreases ACL strain in all positions. However, co-contraction of the hamstrings is not enough to overcome the strain produced by the quadriceps.7 As the knee moves into extension, female athletes take a significantly longer time to activate their hamstrings than do their male counterparts.8,9 At initial contact, males take approximately 150 ms to achieve their peak flexion angle compared with females, who take approximately 200 ms. Landing from a jump, in-line deceleration, and pivoting all involve eccentric contraction of the quadriceps to prevent the extended knee from collapsing into flexion. In laboratory studies, multiple authors4–6 have demonstrated significant anterior translation of the tibia with quadriceps contraction, particularly at 0 to 45 degrees of flexion. This anterior translation force is even greater when the quadriceps contraction is combined with a joint compressive force.4 These findings are the basis for ACL prevention strategies that emphasize proper biomechanics to address proper landing kinematics (hip and knee flexion while avoiding genu valgum), increase peak flexion angles, and improve hamstring activation and strength. Most prevention programs attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. The studies to date that focused on biomechanical modifications have resulted in the reduction of lower-extremity injuries in athletes. However, the studies 43

Anterior Crucite Ligament Injury

In an attempt to analyze existing ACL prevention programs, the studies are grouped and reviewed by their approach to injury prevention, beginning with the more global interventions and working up to the more comprehensive programs. Ettlinger et al25 looked at the effectiveness of an educational program to prevent ACL injury among downhill skiers by increasing awareness of injury mechanism and avoidance. Several studies have looked at the effect of isolated proprioception training on ACL injury risk, whereas a slightly more involved approach included neuromuscular training in landing and cutting techniques. Another pair of studies looked at the efficacy of technique training coupled with strengthening. Several more studies used a combination of neuromuscular training modalities. Finally, a number of studies have used a comprehensive approach to prevention of ACL injury, working on strength, flexibility, and agility as well as proprioception and plyometric training. The studies to date are summarized in Table 5-2.

awareness. In this prospective nonrandomized trial, 4000 on-slope alpine ski instructors and patrollers in 20 ski areas completed training and reporting requirements during the 1993–1994 ski season. The training kit included a 19-minute ACL awareness training videotape that showed 10 recorded ACL injuries sustained by alpine skiers of various levels, as well as various written materials. The videotape used guided discovery, allowing viewers to visualize carefully selected stimuli and incorporate this information into their skiing to avoid high-risk behavior and manage high-risk situations to reduce the risk of ACL injury. Participants also underwent an awareness training session that included proper body positioning, understanding of the phantom-foot ACL injury mechanism, and strategies to avoid high-risk positions as well as effective reaction strategies. The two seasons prior to the intervention season served as historical controls, and area employees had sustained an average of 31 serious ACL sprains per season. During the intervention season, employees sustained 16 serious ACL sprains, 6 in the untrained group and 10 in the trained group, which was a 62% reduction compared with the normalized expected number of 26.6 ACL injuries in the trained individuals (P < 0.005). This study demonstrates that educational efforts and visual aids to increase awareness effectively reduce the number of significant ACL injuries in an alpine skiing population. A significant aspect of this study was the lack of physical biomechanical intervention. Based on the success of other intervention studies, it would be interesting to look at the effect of a similar awareness program combined with specific biomechanical training for alpine skiers.

Education

Isolated Strengthening and Conditioning

vary widely both in their approach to injury prevention and the validity of the study design. Most studies to date have been nonrandomized, and very few have been conducted as randomized, controlled trials. Nevertheless, a number of common elements tie these programs together. Most include one or more of the following: traditional stretching, strengthening, awareness of high-risk positions, technique modification, aerobic conditioning, sports-specific agility, proprioceptive and balance training, and plyometrics. The relation of these components to specific risk factors for ACL injury has been summarized in Table 5-1.

Results of Studies Published to Date

25

Ettlinger et al used a relatively simple approach to prevention of ACL injury in downhill skiers, attempting to modify high-risk–related behavior through education and increased

Cahill and Griffith26 looked at the effect of incorporating weight training into preseason conditioning for high-school American football teams. Over the 4 years of the study, they

TABLE 5-1 Potential Biomechanical Deficits and Suggested Interventions Position

Intervention Strategy

Method of Intervention

Extended knee at initial contact

Knee flexion

Concentric hamstring control and soft landing

Extended hip at initial contact

Hip flexion

Iliopsoas and rectus femoral control and soft landing

Knee valgus with tibial-femoral

Address dynamic control, decrease dynamic

Lateral hip control upon landing

loading

valgus

Balance deficits

Proprioception drills

Dynamic balance training

Skill deficiency

Improve agility

Agility drills to address deceleration techniques and core stability

44

TABLE 5-2 Summary of Anterior Cruciate Ligament Prevention Studies STUDY

DESIGN

SPORT

N Int

Cahill, 1978

P/NR

Caraffa, 1996

P/NR

Combination

Skiing

Education Strength Proprio Plyo Agility Flex
ACL Injuries/Injury Rate

Control

4000 na

M/F




62% #


S

300{ 300{

M




87% # noncontact

P/R

S

121

100

F




No change (intervention group 4/5 ACL injuries)

Hening, 1990

P/NR

BB

na

na

F







89% # noncontact

Wedderkopp, 1999

P/R/C

TH

111

126

F










No ACL specific data

Pfeiffer, 2004

P/NR

S/VB/BB

577

862

F







No change

Hewett, 1999

P/NR

S/VB/BB

366

463

F*




Myklebust, 2003

P/NR

TH

855

942

F

Heidt, 2000

P/R

S

42

258

F

Olsen, 2005

P/R/C

TH

958

879

Mandelbaum, 2005

P/NR

S

Gilchrist, 2004

P/R/C

S



















M/F




1041 1905

F

575

F

854




72% #







Elite players 62% #










No significant change













80% # knee ligament injury
















88% # year 1, 74% # year 2
















72% #

P, Prospective; R, randomized; NR, nonrandomized; C, controlled; S, soccer; VB, volleyball; BB, basketball; TH, team handball. Estimate.

63% # surgical knee injuries 86% # concomitant ACL & MCL

M

*Study also included male controls. {

RESULTS

American football 1227 1254

Soderman, 2000

Comprehensive

P/NR/C

TRAINING MODALITIES

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete

Type of Intervention Program

Isolated

Ettlinger, 1995

GENDER

5

45

Anterior Crucite Ligament Injury noted a reduction in reported knee injuries and knee injuries that required surgery in the intervention group.

Isolated Proprioceptive Training Two studies have looked at the effect of isolated proprioceptive training on ACL injury risk, both in soccer players. Caraffa et al27 conducted a nonrandomized prospective study with 600 semi-professional and amateur soccer players in Umbria and Marche, Italy. Twenty teams (10 amateur and 10 semi-professional teams; Group A) underwent proprioceptive preseason training in addition to their regular training session. The control group (Group B) consisted of 20 teams (10 amateur and 10 semi-professional teams) and continued training in their usual fashion. The intervention group (A) was subjected to a five-phase progressive balance training program consisting of the following: no balance board, rectangular balance board, round balance board, combination (rectangular/round), and a biomechanical ankle platform system (BAPS) board (Camp Jackson, MI). The duration/ frequency was 20 minutes per day for 2 to 6 days per week, including a minimum of 3 times per week during the season. The groups were followed for 3 years, and the senior author evaluated all players with a potential knee injury. Group A (intervention) reported 10 arthroscopically confirmed ACL injuries over three seasons (0.15 ACL injuries per team/season) compared with Group B (control), which reported 70 such injuries (1.15 ACL injuries per team/season) (P < 0.001). Unfortunately, no differentiation was made between contact and noncontact ACL injuries. Soderman et al28 conducted a randomized, prospective controlled trial looking at the effectiveness of a balance board training program to reduce injuries in female soccer players. A total of 13 teams in the Swedish second and third division participated in the study, with seven teams (N ¼ 121 players enrolled, 62 completed) in the intervention group and six teams (N ¼ 100 players enrolled, 78 completed) in the age- and skill-matched control group through one outdoor season. The intervention consisted of a 10- to 15-minute balance board training program in addition to regularly scheduled games and practices. The players were instructed to complete the program daily for 30 days and continue with three sessions per week thereafter. Injuries were assessed with regard to number, incidence, type, and location. The intervention group had more major injuries (8) compared with the control group (1) (P ¼ 0.02) and a total of four ACL injuries were reported in the intervention group compared with one in the control group. Although a major limitation of this study was the 37% dropout rate, balance board training alone did not decrease the incidence of ACL injury in this cohort. Based on these two studies, the role for isolated proprioceptive training in efforts to prevent ACL injury is 46

unclear. A major concern is that the training methods used in both of these studies involve a large commitment both in terms of training time and financial cost of equipment, which may decrease compliance with regard to large-scale injury-prevention efforts.

Neuromuscular Training: Technique Injury prevention has also been considered with the design of a neuromuscular training program to modulate existing athletic technique. Henning29 implemented a prevention study in two NCAA Division I female basketball programs over the course of 8 years. Henning proposed that the increased rate of ACL injury in female athletes was primarily functional, being related to knee position and muscle action during dynamic movement. In knee extension, the quadriceps exerts a significant anterior translational force on the tibia, thus imparting a shear force on the ACL. Conversely, as the knee moves into flexion, the anterior translational force on the tibia is decreased, thereby decreasing the torque on the ACL secondary to the contraction of the hamstrings. In order to decrease the risk of ACL injury, Henning proposed that the athletes cut, land, and decelerate with knee and hip flexion. In addition, he proposed a rounded cut maneuver instead of a sharp or more acute angle during the cut cycle. He also proposed that a one-step stop deceleration pattern should be avoided and a three-step quick stop be instituted instead. This intervention program was geared at changing player technique, stressing knee flexion upon landing, using accelerated rounded turns, and decelerating with a multistep stop. This protocol was completed on the basketball court without any additional equipment requirements. The intervention group was noted to have an 89% reduction in the rate of occurrence of ACL injuries.29 Sadly, Dr. Henning's death in 1991 prevented the publication of this research. However, his research served as the crucial foundation of numerous prevention programs that ensued.

Neuromuscular Training: Technique and Strengthening Henning's concept of athletic modulation has been widely accepted and expounded. Wedderkopp et al31 tested a program including functional strengthening and balance training (use of an ankle disc for 10 to 15 minutes at all practice sessions). Teams were randomized into two groups, with a total of 11 teams (N ¼ 111) in the intervention group and 11 teams (N ¼ 126) in the control group. The group using the ankle disc incurred 14 injuries compared with 66 injuries in the control group (P < 0.01). The control group had a lower rate of injury during practice (0.34 per 1000 hours versus 1.17 per 1000 hours; P < 0.05) and games (4.68 per 1000 hours versus 23.38 per 1000

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete hours; P < 0.01). The intervention group suffered two knee injuries whereas the control group incurred eight knee injuries. No data specific to ACL injury was provided. Pfeiffer et al32 developed the Knee Ligament InjuryPrevention (KLIP) program, involving 15 minutes of strengthening and plyometric activities, for female high-school soccer, volleyball (VB), and basketball (BB) players. In the first season of a 2-year, nonrandomized prospective study, 43 schools participated in the program (17 BB: N ¼ 191; 11 soccer: N ¼ 189; 15 VB: N ¼ 197) and 69 schools served as the control group (28 BB: N ¼ 319; 14 soccer: N ¼ 244; 27 VB: N ¼ 299). The study design included a training session for the coaches and athletic trainers and weekly compliance checks for athlete participation for both games and practices. No significant difference between the two groups was found after one season: there were three arthroscopically confirmed ACL injuries reported in the intervention athletes (incidence rate 0.167) compared with four (incidence rate 0.078) in the control group. Anecdotally, there were no noncontact ACL injuries in the intervention soccer and volleyball players; all of the injuries in the intervention group occurred among basketball players. Possible explanations for the lack of impact include the abridged duration of this intervention program (9 weeks) and the fact that the program was conducted post-training. Neuromuscular fatigue at the end of training may directly affect biomechanical technique of the athlete and limit any potential protective benefit of ACL injury-prevention programs.

Neuromuscular Training: Varied Other studies have incorporated additional dimensions of neuromuscular training into ACL prevention efforts. The Cincinnati Sportsmetric includes flexibility, strengthening (through weight training), and plyometric activities over a duration of 60 to 90 minutes. Hewett et al33 researched the effect of this program on the incidence of knee injury in high school–age soccer, volleyball, and basketball athletes. Fortythree teams (N ¼ 1263 athletes), including 15 female teams (N ¼ 366), implemented the program, and 15 additional female teams (N ¼ 463) served as the same-sex untrained control. Thirteen male sports teams (N ¼ 434) served as the male control group. Coaches and trainers implemented the program based on a videotape and manual. The program was performed 3 days per week on alternate days. Seventy percent of the intervention athletes (248/366) completed the entire 6-week program, and the remainder completed at least 4 weeks of training to be included in the study. The incidence of serious knee injuries (N ¼ 14) in the female control group was 0.43 per 1000 player-exposures, compared with 0.12 in the female intervention group (P ¼ 0.05) and 0.09 in the male control group. The intervention group also had a lower rate of noncontact injuries (P ¼ 0.01) and noncontact ACL injuries (P ¼ 0.05). The

5

incidence of noncontact knee injury was 0.35 per 1000 player-exposures in the control group, compared with 0 in the intervention group and 0.05 in the male control group. When the data were stratified according to sport, no ACL injuries were reported in volleyball players. Among the soccer athletes, there were five ACL injuries reported among the female control athletes (0.56 per 1000 playerexposures), none among the female intervention athletes, and one among the male control group (0.12 per 1000 player-exposures). Among the basketball players, eight ACL injuries were reported; five among the female control athletes (0.48 per 1000 player-exposures), two among the trained athletes (0.42 per 1000 player-exposures), and one among the male controls (0.08 per 1000 player-exposures). When the data were stratified with regard to sport, the distribution of athletes varied widely. The intervention female group included 185 volleyball players, 97 soccer players, and 84 basketball players. The control female group included 81 volleyball players, 193 soccer players, and 189 basketball players. The male control group included 209 soccer players and 225 basketball players. The discrepancy within gender and respective sport cohorts weakens the strength of the study's conclusion. In addition, the number of ACL injuries reported throughout this prospective study was lower compared with historical controls.2,5,34 ACL injuries have also been problematic for European team handball players. Myklebust et al35 conducted a nonrandomized prospective study looking at 900 Divisions I–III competitive female handball players over a 3-year period in Norway. Sixty teams (942 players in the 1998–1999 season) served as the control athletes (CAs), and 58 teams (855 players in the 1999–2000 season) and 52 teams (850 players in the 2000–2001 season) served as the intervention athletes (IAs). The intervention consisted of a 15-minute program focused on landing, cutting, and planting technique with 5 minutes spent on each of three exercise components: floor, balance mat, and wobble board. The program was 5 weeks long, with different exercises introduced each week. The program was to be completed three times per week during the first 5 to 7 weeks and then once per week during the season. A physical therapist was designated to each team to assess compliance during the second intervention season (2000–2001). Special equipment included an instructional videotape, a poster delineating the tasks to be completed, six balance mats, and six balance boards. Teams were required to conduct a minimum of 15 training sessions over the 5- to 7-week period with a minimum of 75% player participation. Only 15 (26%) of the 58 teams from season 2 and 15 (29%) of the 52 teams from season 3 completed the necessary number of sessions, although compliance was higher among the elite division teams (42% and 50%, respectively). 47

Anterior Crucite Ligament Injury Overall, there were 29 ACL injuries during the control season, 23 injuries during the first intervention season (odds ratio [OR], 0.87; confidence interval [CI], 0.50–1.52; P ¼ 0.62) and 17 injuries during the second intervention season (OR, 0.64; CI, 0.35–1.18; P ¼ 0.15). However, during the second intervention season, 14 ACL injuries occurred in players with no training (2.2%) compared with 3 ACL injuries in the players who completed training (1.1%) (P ¼ 0.31). In the elite division alone, 4 ACL injuries occurred in the players with no training (8.9%) compared with 1 ACL injury in those who completed training (0.6%) (P ¼ 0.0134). This intervention included elements of plyometric activities, proprioception, and agilities but did not include any elements of strength. Limitations of the study include nonrandomization of the subjects, insufficient power, and control data that were collected during an earlier season. Strengths of the study include measures of compliance by a medical clinician (physical therapist) and the use of an educational videotape and poster. The study suggests that the inclusion of a neuromuscular balance–based training program may impart some protective benefit to the ACL.

Neuromuscular Training: Comprehensive A number of comprehensive ACL injury programs have been proposed in the literature. These programs incorporate a full range of neuromuscular training, including strengthening, flexibility, agility, proprioception, and plyometrics. Heidt et al34 developed the Frappier Acceleration Program (FAP) as a 7-week preseason training program to address ACL injuries in the high-school–age female soccer population. Three hundred female soccer players were followed over the course of 1 year (one high-school season and one club/select season). The control group included 258 athletes, whereas the intervention group included 42 athletes. The Frappier Acceleration Program consisted of sports-specific aerobic conditioning, plyometrics, sports cord resistance drills, strength training, and flexibility that was individually customized by sport, player position, and specific deficits. The plyometric progression was from unidirectional to bidirectional to multidirectional and vertical challenge (2-inch increments using foam obstacles). Injuries were defined as a player missing practice or a game, and athletic exposures were not recorded in this study. Although there was a significant reduction in injuries, from 91 (37%) in the control group to 7 (14%) in the intervention group (P < 0.01), there was no significant difference in terms of ACL injury: 8 (3.1%) in the control group compared with 1 (2.4%) in the intervention group. Given the small sample size of the intervention group, the study was not sufficiently powered to find significant differences. As with the Cincinnati Sportsmetric Program, the FAP was designed as a preseason protocol with no in-season continuation. In addition, because of the complicated equipment requirements (i.e., treadmill, 48

plyometric box), the training has to be completed in a facility, and compliance could potentially be inhibited by cost. Olsen et al36 studied a program designed to prevent lower limb injury in youth team handball. European team handball clubs (120 teams; intervention ¼ 61 teams, 958 players; control ¼ 59 teams, 879 players) participated in an 8-month intervention program that consisted of four sets of exercise lasting 15 to 20 minutes. The training consisted of warm-up exercises (jogging, backward running, forward running, sideways running, and speed work), technique (plant, cut, and jump shot landing), balance (passing, squats, bouncing, perturbation), and strength and power (squats, bounding, jumps, hamstrings). Each club was instructed on how to perform the program and was issued a training handbook, five wobble boards (Norpro, Norway), and five balance mats (Airex, Switzerland). The program focused on proper biomechanics during landing, core stability, and inter-rater feedback between team members. The intervention teams consisted of 16- to 17-year-old males and females who completed 15 consecutive training sessions at the start of the season, followed by 1 training session per week for the remainder of the season. There were 66 (6.9% of players) lower limb injuries reported in the intervention group (IG) compared with 115 (13.1%) in the control group (CG) (relative risk, 0.51; 95% CI, 0.36–73; P < 0.001). A total of 19 acute knee injuries (2.0%) were recorded in the IG compared with 38 (4.3%) in the CG (relative risk, 0.45; 95% CI, 0.25–0.81; P ¼ 0.007). There were 3 knee ligament injuries reported in the IG compared with 14 in the CG (relative risk, 0.20; 95% CI, 0.06–0.70; P ¼ 0.01). All three knee ligament injuries in the IG were ACL injuries, whereas 10 of the 14 reported knee injuries in the CG were ACL injuries. A commendable 87% compliance rate was reported with the study. Many of these intervention programs require special equipment, specialized training, or significant time commitment. In 1999 an expert panel convened by the Santa Monica (California) Orthopedic and Sports Medicine Research Foundation designed the ACL “PEP Program: Prevent Injury and Enhance Performance.” This prevention program consists of warm-up, stretching, strengthening, plyometrics, and sport-specific agilities to address potential deficits in the strength and coordination of the stabilizing muscles around the knee joint. It was designed as an alternative warm-up so that the desired activities could be performed on the field during practice without specialized equipment for ease of implementation. The program consists of an educational videotape or DVD that demonstrates proper and improper biomechanical technique of each prescribed therapeutic exercise. An entire team can complete the 19 components in less than 20 minutes.37 An early nonrandomized study among highly competitive 14- to 18-year-old female club soccer players using the

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete program demonstrated promising results.37 During the first year of the study (2000), 1041 female club soccer players (52 teams) performed the PEP program, and 1902 players (95 teams) served as the age- and skill-matched controls. There were 2 ACL tears (0.2 ACL injuries per athlete-exposure) in enrolled subjects versus 32 ACL tears (1.7 ACL injuries per athlete-exposure) in the control group—an 88% decrease in ACL ligament injury. In year 2 (2001) of the study, four ACL tears were reported in the intervention group, with an incidence rate of 0.47 injuries per athlete-exposure. Thirty-five ACL tears were reported in the control group, with an incidence rate of 1.8 injuries per athlete-exposure. This corresponds to an overall 74% reduction in ACL tears in the intervention group compared with an age- and skill-matched control group in year 2. The limitations of this study include nonrandomization of the subjects, no consistent direct oversight of the intervention, and compliance measurements that were only completed in a small subset of intervention teams. The strengths of the PEP Program include the fact that it is an on-field warm-up program that requires only traditional soccer equipment (cones and soccer ball). It is completed two to three times per week over the course of the 12-week soccer season and is 20 minutes in duration. It includes progressive strength, flexibility, agility, plyometric, and proprioceptive activities to address the deficits most commonly demonstrated in the female population. Deceleration patterns are addressed, stressing the multistep deceleration pattern and proper landing technique, and it encourages knee and hip flexion while landing on the ball of the foot and avoiding genu valgum by using the abductors and lateral hip musculature. In addition, because the program is designed as a warm-up, compliance rates are higher and the element of neuromuscular fatigue does not affect the performance of the therapeutic exercises. This aforementioned study was followed by a randomized controlled trial using the PEP Program in Division I NCAA women's soccer teams in the 2002 fall season.38 Sixtyone teams with 1429 athletes completed the study, with 854 athletes participating on 35 control teams and 575 athletes participating on 26 intervention teams. No significant differences were noted between intervention and control athletes with regard to age, height, weight, or history of past ACL injuries. After using the PEP Program during one season, there were 8 ACL injuries in the intervention athletes (IA) (rate of 0.14) versus 18 in control athletes (CA) (rate of 0.25) (P ¼ 0.15). There were no ACL injuries reported in IA during practices versus 6 in CA (0.10) (P ¼ 0.01). During game situations, the difference was nonsignificant (IA, 7; CA, 12; P ¼ 0.76). Noncontact ACL injuries occurred at more than three times the rate in CA (N ¼ 10; 0.14) than in IA (N ¼ 2; 0.04) (P ¼ 0.06). Control athletes with a prior history of ACL injury suffered a reoccurrence five times more

5

frequently than the IA group (0.10 versus 0.02; P ¼ 0.06); this difference reached significance when limited to noncontact ACL injuries during the season (0.06 versus 0.00; P < 0.05). There was a significant difference in the rate of ACL injuries in the second half of the season (weeks 6–11; IA, 0.00; CA, 0.18) (P < 0.05). This would support the concept that it takes approximately 6 to 8 weeks for a biomechanical intervention program to impart a neuromuscular effect. Overall, these studies provide evidence that prevention-training programs have a quantifiable effect on ACL injury risk. This has been demonstrated in male and female athletes from various sports and across different age groups. Only three of the reviewed studies showed no effect of training on ACL injury risk; two of them were significantly underpowered and the third implemented the prevention program post-training and for a relatively short duration (9 weeks). Eight studies demonstrate a significant decrease in ACL injury risk for some or all of the study population. Prospective studies of comprehensive prevention programs in large cohorts have been particularly encouraging. Nevertheless, a number of important questions remain.

AREAS FOR FURTHER RESEARCH Program Specifics Practically, a cost-benefit analysis needs to be considered prior to initiating an injury-prevention program on a large scale. First, what equipment, if any, is necessary, and at what cost? Extensive and more expensive equipment is necessary for programs such as the Frappier Acceleration Program,34 the Cincinnati Sportsmetric program,33 and the various programs using some form of a balance board.30,31,34,35 Other successful programs such as PEP37,38 and the Henning program29 do not have such prohibitive requirements. Secondly, what is the minimal time commitment needed to provide adequate protection? How long and how frequent should training sessions be? When should these programs be introduced? What is the minimum duration of an injury-prevention program, or does it need to be continued, perhaps at a lesser frequency throughout the course of the season? When initiating a neuromuscular intervention program, it takes approximately 4 to 6 weeks to impart a benefit onto the athlete. Most of the programs studied to date have a relatively intense start-up period for 4 to 6 weeks followed by less frequent, and in some cases, no additional training.

Timing of Intervention Does the age of the athlete matter, and would intervention at an earlier age provide longer-lasting and perhaps better protection, or will “booster” training be necessary throughout the 49

Anterior Crucite Ligament Injury career of any athlete at risk? The young female athlete 15 to 25 years of age is known to be at particularly high risk for ACL injury and may need different treatment than other populations. The Santa Monica Orthopedic Group is currently collaborating with the University of Southern California to delineate the appropriate age to introduce such programs and to determine what elements of the program effectively change faulty biomechanical patterns.

How Do These Programs Work? More broadly, what is the optimal ACL injury-prevention program? In order to answer this question, it becomes necessary to determine the precise biomechanical adaptations that develop in athletes as a result of participating in these programs. The “pathokinetic chain” of increased hip adduction moment, decreased hip abduction control, and increased hip adduction angles is surmised to place the lower extremity in a valgus position. With increased internal rotation moment and motion at the knee joint, possibly in combination with ground reaction force, the ACL may be overloaded to failure. How do the injury-prevention programs make this less likely to occur? Although further clinical studies may offer some insight into the optimal prevention program, a definitive answer will remain elusive until the biomechanical implications of clinically successful intervention programs are studied and better understood.

Individual Versus Population-Based Programs Once the specific responsive adaptations resulting from an injury-prevention program are known, will screening become possible? If an athlete already exhibits the biomechanical behaviors that are known to result from injury-prevention training, is there any benefit to completing or continuing the program? Can individuals be assessed and undergo tailored interventions as opposed to a global program? As we continue our research efforts to further delineate the mechanism(s) of ACL injury, it may be possible to “red flag” specific individuals who demonstrate biomechanical patterns that may directly correlate to an increased risk of ACL injury. In addition, the age of exposure to a neuromuscular training program may be a key piece of the prevention puzzle. If the program is instituted prior to the onset of puberty and, perhaps, prior to faulty biomechanical patterns being neuromuscularly ingrained, can we avoid the development of these patterns in the first place?

Effect on Performance Another important issue is the effect of ACL injuryprevention programs on athletic performance. This is 50

particularly important when the relatively poor compliance with some of the injury-prevention programs reviewed previously is compared with the much higher rates of compliance, upwards of 80% to 90%, that have been reported with training targeted toward improving performance.39–43 Recent studies have begun to assess this issue, and the results are encouraging. In 1996, before the program had been found to decrease ACL injury risk, Hewett et al44 reported that the Sportsmetric program increased vertical jump, improved control of dynamic loading of the knee, and increased hamstring strength, power, and peak torque in female volleyball players. Wilkerson et al45 looked at the impact of the Cincinnati Sportsmetric program on performance in a small cohort of female collegiate basketball players. They found significantly increased hamstring strength in the intervention group but no other changes in either group. Meyer et al43 looked at the effect of an enhanced training program based on the Cincinnati Sportsmetric program on performance. In this study, female athletes demonstrated increased strength and power and improved knee biomechanics after training compared with no change in the control group. Paterno et al47 created their own program of exercises similar to those described in the literature for injury prevention and found improved single-limb total stability and anteroposterior stability. There was no control group in this study. Holm et al48 looked at the influence of the program used by Myklebust35 on female team handball players and found an improvement in dynamic balance but no other significant changes. Again, there was no control group for this study. Thus, although these studies suggest there may be some improvement in performance from participation in ACL injury-prevention programs, further study, particularly with larger, well-designed studies, is needed to more precisely assess the impact of such programs on performance.

CONCLUSION There appears to be a quantifiable reduction in ACL risk for athletes, particularly females, who complete well-designed injury-prevention programs. Most of these programs attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. An emphasis on proper landing technique, landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion upon landing and with lateral (cutting) maneuvers; avoiding excessive genu valgum at the knee upon landing and squatting; increasing hamstring, gluteus medius, and hip abductor strength; and addressing proper deceleration techniques are activities that seem to be inherent in each of the aforementioned ACL prevention protocols. Further electromyography and biomechanical analysis is warranted to better understand

Analysis of Anterior Cruciate Ligament Injury-Prevention Programs for the Female Athlete and identify the mechanism(s) of ACL injury and the activities that offer a protective effect to the ACL.

References 1. Garrick JG, Requa RK. Anterior cruciate ligament injuries in men and women: how common are they? In Griffin LY (ed): Prevention of noncontact ACL injuries. Rosemont, IL, 2001, American Academy of Orthopaedic Surgeons, pp 1–9. 2. Bahr R, Holme I. Risk factors for sports injuries—a methodological approach. Br J Sports Med 2003;37:384–392. 3. Feagin JA, Jr, Lambert KL, Cunningham PR, et al. Consideration of the anterior cruciate ligament injury in skiing. Clin Orthop Relat Res 1987; 216:13–18. 4. Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am 1997;79:1556–1576. 5. Griffin LY, Agel J, Albohn MJ, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 2000;8:141–150. 6. Myklebust G, Holm I, Maehlum S. Clinical, functional and radiological outcome 6–11 years after ACL injuries in team handball players— a follow-up study. Am J Sports Med 2003;31:981–989. 7. Daniels DM, Stone MI, Dobson BL, et al. Fate of the ACL injured patient: a prospective outcome study. Am J Sports Med 1994;22:632–644. 8. Ferretti A, Conteduca F, DeCarli A, et al. Osteoarthritis of the knee after ACL reconstruction. Int Orthop 1991;15:367–371. 9. Fithian DC, Paxton EW, Stone ML, et al. Prospective trial of a treatment algorithm for the management of anterior cruciate ligament injured knee. Am J Sports Med 2005;33:23–28. 10. Lohmander LS, Osteber A, Englind M, et al. High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Ann Rheum Dis 2004;10:314–352. 11. Myklebust G, Maehlum S, Holm I, et al. A prospective cohort study of ACL injuries in elite Norwegian team handball. Scand J Med Sci Sports 1998;8:149–153. 12. Roos H, Adalberth T, Dahlberg L. Osteoarthritis of the knee after injury to the anterior cruciate ligament or meniscus. The influence of time and age. Osteoarthr Cart 1995;3:261–267. 13. Sommerlath K, Lysholm J, Gillquist J. The long term course after treatment of acute anterior cruciate ligament ruptures. Am J Sports Med 1991;19:156–162. 14. Von Porat A, Roos EM, Roos H. High prevalence of osteoarthritis 14 years after an anterior cruciate ligament tear in male soccer players: a study of radiographic and patient relevant outcomes. Ann Rheum Dis 2004;63:269–273. 15. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. Am J Sports Med 1995; 23:694–701. 16. Gillquist J, Messner K. Anterior cruciate ligament reconstruction and the long-term incidence of gonarthrosis. Sports Med 1999;27:143–156. 17. Chandy TA, Grana WA. Secondary school athletic injury in boys and girls: A three year comparison. Phys Sportsmed 1985;13:106–111. 18. Gray J, Taunton JE, McKenzie DC, et al. A survey of injuries to the anterior cruciate ligament of the knee in female basketball players. Int J Sports Med 1985;6:314–316. 18a. Seitz H, Marlovits S, Wielke T, Vescei V. Meniscus lesions after isolated anterior cruciate ligament rupture. Wien Klin Wochenschr 1996;22:727–730. 19. Lindenfeld TN, Schmitt DJ, Hendy MP, et al. Incidence of injury in indoor soccer. Am J Sports Med 1994;22:364–371.

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20. Malone TR, Hardaker WT, Garrett WE, et al. Relationship of gender to ACL injuries in intercollegiate basketball players. J South Orthop Assoc 1992;2:36–39. 21. Strand T, Wisnes AR, Tvedte R, et al. ACL injuries in team handball. J Nor Med Assoc 1990;110:45–48. 25. Ettlinger CF, Johnson RJ, Shealy JE. A method to help reduce the risk of serious knee sprains incurred in alpine skiing. Am J Sports Med 1995;23:531–537. 26. Cahill BR, Griffith EH. Effect of preseason conditioning on the incidence and severity of high school football injuries. Am J Sports Med 1978;6:180–184. 27. Caraffa A, Cerulli G, Projetti M, et al. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthrosc 1996;4:19–21. 28. Soderman K, Werner S, Pietila T, et al. Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players? A prospective randomized intervention study. Knee Surg Sports Traumatol Arthrosc 2000;8:356–363. 29. Henning CE, Griffis ND. Injury prevention of the anterior cruciate ligament (videotape). Wichita, KS, 1990, Mid-America Center for Sports Medicine. 31. Wedderkopp N, Kaltoft M, Lundgaard B, et al. Prevention of injuries in young female players in European team handball. A prospective intervention study. Scand J Med Sci Sports 1999;9:41–47. 32. Pfeiffer RP, Shea K, Grandstrand S, et al. Effects of a knee ligament injury prevention (KLIP) program on the incidence of noncontact ACL injury: a two-year prospective study of exercise intervention in high school female athletes. Podium presentation at the American Orthopaedic Society for Sports Medicine (AOSSM), Specialty Day, San Francisco, CA, March, 2004. 33. Hewett TE, Lindenfeld TN, Riccobene JV, et al. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med 1999;27:669–706. 34. Heidt RS, Jr, Sweeterman LM, Carlonas RL, et al. Avoidance of soccer injuries with preseason conditioning. Am J Sports Med 2000;28:659–662. 35. Myklebust G, Engebretsen L, Braekken IH, et al. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sport Med 2003;13:71–78. 36. Olsen OE, Myklebust G, Engebretsen L, et al. Exercises to prevent lower limb injuries in youth sports: cluster randomised controlled trial. BMJ 2005;330:449. 37. Mandelbaum BR, Silvers HJ, Watanabe DS, et al. Effectiveness of a neuromuscular and proprioceptive training program in preventing anterior cruciate ligmaent injuries in female athletes. 2-year followup. Am J Sports Med 2005;33:1003–1010. 38. Gilchrist J, Mandelbaum BR, Silvers HJ. AAOS Annual Meeting, AOSSM Specialty Day, San Francisco, CA, March 2004. 39. Ben-Sira D, Ayalon A, Tavi M. The effect of different types of strength training on concentric strength in women. J Strength Cond Res 1995;9:143–148. 40. Hakkinen K, Alen M, Kraemer WJ, et al. Neuromuscular adaptations during concurrent strength and endurance training versus strength training. Eur J Appl Physiol 2003;89:42–52. 41. Kraemer WJ, Duncan ND, Volek JS. Resistance training and elite athletes: adaptations and program considerations. J Orthop Sports Phys Ther 1998;28:110–119. 42. Kraemer WJ, Hakkinen K, Triplett-McBride NT, et al. Physiological changes with periodized resistance training in women tennis players. Med Sci Sports Exerc 2003;35:157–168. 43. Wroble RR, Moxley DR. The effect of winter sports participation on high school football players: strength, power, agility and body composition. J Strength Cond Res 2001;15:132–135.

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Anterior Crucite Ligament Injury 44. Hewett TE, Stroupe AL, Nance TA, et al. Plyometric training in female athletes: decreased impact forces and increased hamstring torques. Am J Sports Med 1996;24:765–773. 45. Wilkerson GB, Colston MA, Short NI, et al. Neuromuscular changes in female collegiate athletes resulting from a plyometric jump-training program. J Athl Train 2004;39:17–23.

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47. Paterno MV, Myer GD, Ford KR, et al. Neuromuscular training improves single-limb stability in young female athletes. J Orthop Sports Phys Ther 2004;34:305–316. 48. Holm I, Fosdahl MA, Friis A, et al. Effect of neuromuscular training on proprioception, balance, muscle strength, and lower limb function in female team handball players. Clin J Sport Med 2004;14:88–94.

PART B CLINICAL

Diagnosis of Anterior Cruciate Ligament Tear INTRODUCTION The overwhelming majority of orthopaedists are very skilled in the diagnosis of anterior cruciate ligament (ACL) tears. However, acute ACL tear is perhaps the most underdiagnosed orthopaedic condition that usually requires surgery because most tears present to emergency room or primary care providers who cannot necessarily be expected to make the diagnosis. The history and exam and diagnostic tests are less reliable than commonly thought, and the presentation is often not “classic.” Failure to refer to an orthopaedist in these cases, or failure of the patient to actually see the referred-to orthopaedist, results in underdiagnosis and delays in diagnosis that can extend over months or years.

DIAGNOSIS IN THE ACUTE VERSUS THE CHRONIC SETTING Diagnosis of complete ACL tears differs in some respects in the acute versus the chronic state regarding the history, physical exam, and diagnostic tests. This chapter will discuss the acute versus chronic diagnostic dichotomy for each of these diagnostic modalities. In the acute setting the diagnosis is primarily of the ACL tear itself, whereas in the chronic setting the diagnosis more often includes the signs and symptoms of secondary damage. Because the most important aspect of ACL reconstruction is the prevention or mitigation of subsequent

meniscal and articular damage to the knee, it is paramount that ACL tears are diagnosed and treated acutely before such further damage occurs.

6

CHAPTER

Chadwick C. Prodromos Brian J. Murphy

PARTIAL TEARS This chapter deals primarily with complete ACL tears. Traditionally, partial tears have been found to produce a smaller degree of anteroposterior (AP) laxity than complete tears on Lachman or instrumented Lachman testing, as described later. Until the present time, the only alternatives have been nonoperative treatment or complete reconstruction, which would necessitate ablation of the remaining ligament. Given these alternatives, nonsurgical treatment has been the usual alternative if less than 50% of the ligament was torn.1 With more awareness of ACL double-bundle anatomy, single-bundle repairs that preserve the remaining ligament have been developed.2 These repairs have been used in some cases of single-bundle partial ACL tear. Lachman testing and arthrometer testing in these cases appear to show 2- to 3-mm asymmetry in anteromedial (AM) bundle tears and 1- to 2-mm asymmetry in posterolateral (PL) bundle tears.3 Arthroscopy is required for definite anatomical diagnosis. The pivot shift is of much greater value in the anesthetized versus the awake patient. Diagnostic criteria as well as surgical indications and techniques in these cases continue to evolve.

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Anterior Cruciate Ligament Injury

HISTORY Acute The history and mechanism of ACL tear are familiar to all orthopaedists.4–10 The history most commonly entails twisting, landing, or a valgus blow to the knee. However, almost any history of knee trauma can be associated with ACL tear. These atypical histories may represent unusual mechanisms or inaccurate remembrances by the patient. The important point is never to eliminate ACL tear from the differential diagnosis based on the history. Classically, swelling is marked within a few hours. However, some ACL tears never produce more than minimal swelling, even acutely. Patients often hear or feel a “pop,” but many do not. Similarly, patients may have felt the knee “go out of place,” or felt their “leg go one way and the body another” but often they have not felt these sensations. Pain may be severe and persisting or may be mild and transient. Nonorthopaedists are aware that ACL tear is a serious injury and are often misled into thinking that the injury “is only a sprain” because the history and exam are much less dramatic than they are expecting for such a serious injury. Team physicians should therefore perform a Lachman test on any knee injury during a game because ACL tears in the heat of competition are often not obvious by the athlete's historical account and sometimes produce little pain initially before swelling sets in. This underdiagnosis by history is particularly true in emergency rooms (ERs), where the diagnosis of ACL tear may not be made by the emergency physician. Patients will often feel that the injury is not serious, especially if they do not have a concomitant meniscal tear, which would have produced its own set of symptoms. This is particularly true if the injury is called a “sprain,” such that the patient in many cases feels that there is no need for orthopaedic follow-up. Because magnetic resonance imaging (MRI) will usually not be ordered at this time, the diagnosis is easily missed. Patients with meniscal or articular cartilage damage will usually have continued symptomatology from their cartilage damage and are more likely to follow-up. Patients with bucket-handle tears and locked knees will virtually always seek further care and be diagnosed accurately by the exam or MRI, or at arthroscopy.

Chronic Chronic ACL tears often present because of pain from a meniscal tear or articular cartilage damage. Patients may or may not give a history of instability. Classically instability will occur during pivoting, but the symptoms can take almost any form. It can be confused with patellar instability, 54

particularly in adolescents, as well as meniscal tear. Any symptom of instability should cause the orthopaedist to rule in or rule out ACL tear.

PHYSICAL EXAM Pivot Shift The pivot shift is a specific but very insensitive test for ACL tear in the nonanesthetized patient.11,12 It is also subject to great interobserver error. Because the pivot shift is often quite painful when positive, has low sensitivity, and usually adds nothing beyond the Lachman test, I (C. Prodromos) use it only rarely for the diagnosis of ACL tear in the office. I do use it routinely in the 1- and 2-year follow-up exams, where its negativity confirms that ACL reconstruction has been successful.

Lachman Test The Lachman test,13 the anterior drawer test in approximately 20 degrees of flexion, is the most reliable exam test for ACL tear11 but is far more reliable in the chronic case, when secondary restraints have stretched and there is less hamstring spasm, than in the acute case. After 21 years of sports medicine practice, I still find the Lachman inconclusive with some frequency in the acute setting, particular in regards to the differential between partial and complete tear, because of persisting hamstring spasm. The firmness of the endpoint may be particularly hard to evaluate. The examiner may or may not be successful in relaxing the hamstrings. Palpating them posteriorly and simultaneously while asking the patient to relax them is often effective. It is important that the patient is in the supine, not sitting, position, and he or she should be instructed to relax the entire body to help relax the knee. The Lachman test should be considered definitive only if it is clearly negative with a firm endpoint. It is important that the examiner be able to differentiate between a negative Lachman test and a false negative caused by this hamstring spasm to avoid missing a torn ACL.

Anterior Cruciate Ligament Versus Posterior Cruciate Ligament Tear A posterior cruciate ligament (PCL) tear produces increased AP laxity and can mimic an ACL tear. Classically there will be increased AP laxity, but with a firm anterior endpoint, with a PCL tear. However, this can also be seen with a healed partial ACL tear. If there is a question of ACL versus PCL tear, then MRI or the quadriceps active test14 should be used to differentiate the two. In addition, it is wise to always

Diagnosis of Anterior Cruciate Ligament Tear arthroscopically inspect the knee before any graft harvesting takes place to make certain that the ACL is in fact completely torn.

Valgus Laxity In patients with coexisting medial collateral ligament insufficiency, and hence valgus laxity, the Lachman test can be false positive. Rotation of the lax proximal medial tibial plateau can mimic translation of the entire proximal tibia if rotation is not carefully controlled by the examiner during the exam. Thus, when the examiner is aware that valgus laxity exists, he or she should pay particular attention to controlling tibial rotation during the test to minimize this possibility. This can be challenging in patients with large-girth lower extremities.

Locking

6

KT-1000 or Other Instrumented Lachman Test The KT-100024–29 (Figs. 6-1 and 6-2) maximum manual examination is a highly accurate method for definitive diagnosis of ACL tear that is heavily relied on in our clinic. When it indicates a complete ACL tear, we generally do not order an MRI scan. A side-to-side difference of more than 4 mm, particularly with an absolute value of 10 or more, is nearly 100% specific for complete ACL tear30 if the examiner is experienced in its use. The more difficult differential may be between complete and partial ACL tear. We have found partial ACL tears to usually have a laxity of 2 or 3 mm. When it is greater, a complete tear has almost always existed. Others have found a slightly larger range.31 Larger differences, up to 4 and perhaps 5 mm, can be seen after ACL reconstruction without graft discontinuity. It is

“Pseudolocking” may be seen classically with partial tears.15,16 However, a knee with a 20-degree or so persisting flexion contracture (i.e., pseudolocking) can occasionally be seen with isolated complete ACL tear from hamstring spasm alone. True locking is seen with ACL tear in combination with displaced bucket-handle meniscal tears. In these cases the “locking” is actually reflex hamstring spasm in response to extension in the presence of the displaced meniscal tear. Thus, the Lachman test is always difficult to perform and frequently false negative because of the hamstring spasm.17

Hemarthrosis The presence of a large hemarthrosis is much more highly associated with ACL tear in adults18–21 than in children.22 Patellar dislocation and fracture are other leading causes of hemarthrosis. The former can usually be accurately diagnosed by physical exam, the latter by radiography. Arthrocentesis is usually not indicated. Its only diagnostic value is in determining whether a large effusion is a hemarthrosis. In most of these cases, an MRI will be ordered, which will provide much more information and spare the patient the pain of the arthrocentesis. If the effusion is sufficiently tense, hemarthrosis may be indicated for pain relief. If MRI is unavailable and the exam is equivocal, then arthrocentesis may be useful. A 16-gauge needle is preferable, but an 18-gauge needle may be used.

FIG. 6-1 Maximum manual examination is the most accurate KT-1000 testing mode.

Patellofemoral Injury Although concomitant ACL tear and patellar dislocation or injury is unusual, it does occur.23 The presence of physical exam signs of acute patellar instability should not cause the examiner to fail to test for ACL instability.

FIG. 6-2 Most complete tears will have a reading of 10 mm or more as well as a side-to-side difference of 4 mm or more on maximum manual testing.

55

Anterior Cruciate Ligament Injury important to point out that the maximum manual test is more reliable than other methods. A 20-lb pull in particular will understate the amount of laxity. The 30-lb pull will as well, but to a lesser extent.32 Other arthrometers are in use, particularly in Europe, with reportedly good results.33 We have no experience with them. As described earlier, PCL tears can mimic ACL tears. The “quadriceps active test”14 performed with the KT-1000 has been shown to reliably differentiate the two.

Examination Under Anesthesia The examination under anesthesia (EUA) dramatically increases the sensitivity of the pivot shift test.12 The accuracy of the KT-1000 is also improved. We may perform both just prior to arthroscopy when the diagnosis is in doubt. The differential in question is usually between a partial and complete ACL tear. EUA may appear to be unnecessary because arthroscopic examination can seemingly determine whether a complete tear exists. However, with partial tears the EUA is a valuable supplement to the arthroscopic findings in determining whether reconstruction is needed. The difference between a partially torn but substantially intact ACL that would do well with conservative treatment versus a completely torn ACL that has scarred in with fibrofatty tissue and is essentially functionless is not always obvious arthroscopically. In these circumstances the EUA is very helpful in helping to determine proper treatment.

FIG. 6-3 A rare tibial eminence avulsion (arrow) in an adult, producing instability equivalent to interstitial anterior cruciate ligament (ACL) tear.

Radiographs Radiographs are typically negative; however, certain radiographic signs may be present. These include the lateral tibial rim or “segond” fracture and posterior lateral tibial plateau fracture or lateral femoral condyle impaction fracture.34 Tibial spine peaking is common in chronic tears but is a nonspecific sign. Tibial eminence fracture is seen occasionally in the skeletally immature and rarely in the skeletally mature (Figs. 6-3 and 6-4). Radiographic signs of a hemarthrosis are usually present.

Magnetic Resonance Imaging Sensitivity rates of 80% to 81% for arthroscopically proven complete ACL tears have been reported using MRI.30,35 Others have reported accuracy rates of more than 90%36,37 and sensitivity and specificity over 95%.38 However, Tsai et al found only a 67% specificity rate for complete tear.39 The MRI was very sensitive for detecting some ACL injury, but it was much less specific for differentiating the complete from the partial tear. This is an important distinction because the former is usually a surgical lesion, whereas the latter is usually not. 56

Although MRI is a useful test, a negative MRI should not rule out an ACL tear that otherwise seems present clinically. The best course of action in such circumstances is to either obtain a KT-1000 exam by a reliable operator and/or to proceed to examination under anesthesia using the pivot shift and Lachman tests and to direct arthroscopic examination if necessary. The normal ACL is both distinctly seen and appears taut (Fig. 6-5). The torn ACL is indistinct and appears lax (Fig. 6-6). Bone bruises (Fig. 6-7) in the lateral compartment are seen in roughly half of acute ACL tears.40,41 Their absence should thus not be relied on to rule out ACL tear. A fracture of the posterior lip of the tibia is another characteristic finding (Fig. 6-8). Transchondral fracture with intact articular cartilage is sometimes also seen (Fig. 6-9). High-field MRI machines generally produce better accuracy for ACL tears than low-field MRI machines and should be obtained where possible. If the only available high-field MRI machine is closed-field and the patient is claustrophobic, oral diazepam may be given. This will enable many such claustrophobic patients to undergo a closed test,

Diagnosis of Anterior Cruciate Ligament Tear

6

FIG. 6-5 The arrow points to a normal anterior cruciate ligament (ACL) on an oblique sagittal T2 weighted image. Note that the ACL is taut and well defined.

FIG. 6-4 A rare tibial eminence avulsion (arrow) in an adult, producing instability equivalent to interstitial anterior cruciate ligament (ACL) tear.

especially if they understand that the improved quality of the images is worth their trouble. Finally, the skill of the radiologist is extremely important. The same study can be interpreted as positive or negative depending on the radiologist's experience. A skilled radiologist can be of great help to the orthopaedist in interpreting difficult cases. False-positive MRIs are less common but also occur. One study found MRI to add no diagnostic accuracy beyond history, physical exam, and radiographs (but not KT-1000) for all ACL tears.42 We believe this is greater clinical diagnostic accuracy than most orthopaedists, including the author, would achieve.

CONCLUSIONS 1 Lachman testing is the most accurate physical exam test for ACL tear diagnosis in the nonanesthetized patient. 2 KT-1000 or other instrumented Lachman test in the hands of an experienced user is a highly accurate method of examination for ACL tear.

FIG. 6-6 The arrow points to a completely torn anterior cruciate ligament (ACL), which appears ill defined and lax within the intercondylar notch on sagittal T2 weighted image.

57

Anterior Cruciate Ligament Injury

FIG. 6-7 The arrows point to some areas of hypointensity on a T1 weighted coronal image, which are consistent with lateral compartmental bone contusions in this patient with complete anterior cruciate ligament (ACL) tear.

FIG. 6-9 Inversion recovery coronal image. The arrow points to buckled black subchondral cortex. Below is intact articular cartilage. The white starburst area above is subchondral bone edema in this patient with complete anterior cruciate ligament (ACL) tear.

3 MRI is a very good test but is less accurate than commonly thought, particularly regarding the differentiation of partial from complete tears. In suspected complete tears with negative MRIs, examination under anesthesia using both the Lachman and pivot shift tests, instrumented Lachman testing, and/or arthroscopic examination should be performed. 4 Very high diagnostic accuracy rates can be obtained by a synthesis of the history, physical exam, and plain radiographs in obvious cases and the addition of MRI, examination under anesthesia, and/or instrumented Lachman testing in questionable cases.

References

FIG. 6-8 Sagittal proton density image. The arrow points to oblique transchondral fracture of the posterior tibia without evidence of step-off of the articular plate in this patient with complete anterior cruciate ligament (ACL) tear.

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1. Noyes FR, Mooar LA, Moorman CT III, et al. Partial tears of the anterior cruciate ligament: progression to complete ligament deficiency. J Bone Joint Surg Br 1989;71:825–833. 2. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at the symposium of the 2006 of the American Academy of Orthopaedic Surgeons. Controversies in Soft Tissues ACL Reconstruction, March, 2006, Chicago. 3. Fu FH. Personal communication. August, 2006. 4. Berns GS, Hull ML, Patterson HA. Strain in the anteriormedial bundle of the anterior cruciate ligament under combined loading. J Orthop Res 1992;10:167–176. 5. Boden BP, Dean GS, Geagin JA, et al. Mechanisms of anterior cruciate ligament injury. Orthopedics 2000;23:573–578.

Diagnosis of Anterior Cruciate Ligament Tear 6. DeMorat G, Weinhold P, Blackburn T, et al. Aggressive quadriceps loading can induce non-contact anterior cruciate ligament injury. Am J Sports Med 2004;32:477–483. 7. Fleming BC, Renstrom PA, Beynnon BD, et al. The effect of weightbearing and external loading on anterior cruciate ligament strain. J Biomech 2001;34:163–170. 8. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med 2005;33:492–505. 9. Markolf KL, Burchfield DM, Sharpiro MM, et al. Combined knee loading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13:930–935. 10. Mazzocca AD, Nissen CW, Geary M, et al. Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament. J Knee Surg 2003;16:148–151. 11. Benjaminse A, Gokeler A, van der Schans CP. Clinical diagnosis of an anterior cruciate ligament rupture: a meta-analysis. J Orthop Sports Phys Ther 2006;36:267–288. 12. Donaldson WF III, Warren RF, Wickiewicz T. A comparison of acute anterior cruciate ligament examinations. Initial versus examination under anesthesia. Am J Sports Med 1985;13:5–10. 13. Ostrowski JA. Accuracy of 3 diagnostic tests for anterior cruciate ligament tears. J Athl Train 2006;41:120–121. 14. Daniel DM, Stone ML, Barnett P, et al. Use of the quadriceps active test to diagnose posterior cruciate ligament disruption and measure posterior laxity of the knee. J Bone Joint Surg Am 1988;70:386–391. 15. Chun CH, Lee BC, Yang JH. Extension block secondary to partial anterior cruciate ligament tear on the femoral attachment of the posterolateral bundle. Arthroscopy 2002;18:227–231. 16. Finsterbush A, Frankl U, Mann G. Fat pad adhesion to partially torn anterior cruciate ligament: a cause of knee locking. Am J Sports Med 1989;17:92–95. 17. Kong KC, Hamlet MR, Peckham T, et al. Displaced bucket handle tears of the medial meniscus masking anterior cruciate deficiency. Arch Orthop Trauma Surg 1994;114:51–52. 18. Sarimo J, Rantanen J, Heikkila J, et al. Acute traumatic hemarthrosis of the knee. Is routine arthroscopic examination necessary? A study of 320 consecutive patients. Scand J Surgery 2002;91:361–364. 19. Adalberth T, Roos H, Lauren M, et al. Magnetic resonance imaging, scintigraphy, and arthroscopic evaluation of traumatic hemarthrosis of the knee. Am J Sports Med 1997;25:231–237. 20. Lundberg M, Odensten M, Thuomas KA, et al. The diagnostic validity of magnetic resonance imaging in acute knee injuries with hemarthrosis. A single-blinded evaluation in 69 patients using high-field MRI before arthroscopy. Int J Sports Med 1996;17:218–222. 21. Maffulli N, Binfield PM, King JB, et al. Acute hemarthrosis of the knee in athletes. A prospective study of 106 cases. J Bone Joint Surg Br 1993;75:945–949. 22. Matelic TM, Aronsson DD, Boyd DW Jr, et al. Acute hemarthrosis of the knee in children. Am J Sports Med 1995;23:668–671. 23. Chiang AS, Shin SS, Jazrawi LM, et al. Simultaneous ruptures of the anterior cruciate ligament and patellar tendon: a case report. Bull Hosp Joint Dis 2005;62:134–136. 24. Rangger C, Daniel DM, Stone ML, et al. Diagnosis of an ACL disruption with KT-1000 arthrometer measurements. Knee Surg Sports Traumatol Arthrosc 1993;1:60–66.

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25. Boyer P, Dijan P, Christel P, et al. Reliability of the KT-1000 arthrometer (Medmetric) for measuring anterior knee laxity: comparison with Telos in 147 knees. Rev Chir Orthop Reparatrice Appar Mot 2004;90:757–764. 26. Bonnaire F, Berwarth H, Munst P, et al. Can the results of cruciate ligament operations be arthrometrically evaluated? A comparison of subjective assessment, Lysholm score, clinical stability classification and measuring stability with the KT 1000 after complex knee injuries. Unfallchirurgie 1995;21:83–91. 27. Anderson AF, Snyder RB, Federspiel CF, et al. Instrumented evaluation of knee laxity: a comparison of five arthrometers. Am J Sports Med 1992;20:135–140. 28. Bach BR Jr, Warren RF, Flynn WM, et al. Arthrometric evaluation of knees that have a torn anterior cruciate ligament. J Bone Joint Surg Am 1990;72A:1299–1306. 29. Liu SH, Osti L, Henry M, et al. The diagnosis of acute complete tears of the anterior cruciate ligament. Comparison of MRI, arthrometry and clinical examination. J Bone Joint Surg Br 1995;77B:586–588. 30. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 31. Gonzalez-Couto E, Klages N, Strubin M. Synergistic and promoterselective activation of transcription by recruitment of transcription factors TFIID and TFIIB. Proc Natl Acad Sci U S A 1997;94:8036–8041. 32. Strand T, Solheim E. Clinical tests versus KT-1000 instrumented laxity test in acute anterior cruciate ligament tears. Int J Sports Med 1995;16:51–53. 33. Anderson AF, Snyder RB, Federspiel CF, et al. Instrumented evaluation of knee laxity: a comparison of five arthrometers. Am J Sports Med 1992;20:135–140. 34. Stallenberg B, Gevenois PA, Sintzoff SA Jr, et al. Fracture of the posterior aspect of the lateral tibial plateau: radiographic sign of anterior cruciate ligament tear. Radiology 1993;187:821–825. 35. Varanda P, Amado P, Monteiro A, et al. Diagnosis of complete anterior cruciate ligament rupture: comparison of clinical examination, MRI and arthrometry. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 36. Vellet AD, Lee DH, Munk PL, et al. Anterior cruciate ligament tear: prospective evaluation of diagnostic accuracy of middle-and high-field strength MR imaging at 1.5 and 0.5 T. Radiology 1995;197:826–830. 37. Vaz CE, Camargo OP, Santana PJ, et al. Accuracy of magnetic resonance in identifying traumatic intraarticular knee lesions. Clinics 2005;60:445–450. 38. Craig JC, Go L, Blechinger J, et al. Three-tesla imaging of the knee: initial experience. Skeletal Radiol 2005;34:453–461. 39. Tsai KJ, Chiang H, Jiang CC. Magnetic resonance imaging of anterior cruciate ligament rupture. BMC Musculoskelet Disord 2004;8:21. 40. Dimond PM, Fadale PD, Hulstyn MJ, et al. A comparison of MRI findings in patients with acute and chronic ACL tears. Am J Knee Surg 1998;11:153–159. 41. Tung GA, Davis LM, Wiggins ME, et al. Tears of the anterior cruciate ligament: primary and secondary signs at MR imaging. Radiology 1993;188:661–667. 42. Kocabey Y, Tetik O, Isbell WM, et al. The value of clinical examination versus magnetic resonance imaging in the diagnosis of meniscal tears and anterior cruciate ligament rupture. Arthroscopy 2004; 21:696–700.

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7

CHAPTER

Elias Tsepis George Vagenas Giannis Giakas Stavros Ristanis Anastasios Georgoulis

60

Nonoperative Management of Anterior Cruciate Ligament Deficient Patients ANTERIOR CRUCIATE LIGAMENT DEFICIENCY: THE NEED FOR MUSCLE STRENGTHENING The knee joint's location in the middle of the lower limb kinetic chain is imposed to high loads, which reach multiple the body mass, particularly in the single stance phase of sport activities.1,2 Rupture of the anterior cruciate ligament (ACL) destabilizes the knee joint,3–5 thus making ACL deficient knees prone to repeated subluxations, which form a potential cause for secondary damage to the joint.6–8 Subsequently, dynamic stabilization through the quadriceps and hamstrings becomes very crucial for the protection of the injured knee.9,10 Apart from its mechanical role, the ACL functions as a sensory organ due to the mechanoreceptors within its substance.11 After its rupture, this function is lost, and therefore optimization of the lower limb muscle properties becomes increasingly important in order to compensate for the resulting anterior and rotational knee instability. Exercise in ACL deficient patients aims at the improvement of various aspects of muscle properties including reflexes, strength, endurance, and coordination with other muscles. Functional exercise that reeducates the neuromuscular coordination holds the central role in rehabilitation programs, as growing evidence supports the development of preprogrammed compensatory muscle activation strategies for efficient shear force dissipation during injured knee loading.12–16 However, the fundamental

issue of the need for strength testing and the value of strengthening exercises still leaves room for investigation. Among the criteria for progression of ACL rehabilitation is the level of quadriceps and hamstring weakness.17,18 Strength testing and exercise have been traditionally incorporated into musculoskeletal rehabilitation regimens. Although the connection between the level of quadriceps strength and functional status has been disputed,19–22 some studies support the interrelation between functional performance of the knee and thigh muscle strength. It is of clinical importance for ACL rehabilitation that patients with greater than normal strength in the injured limb seem to reduce abnormalities during low- and high-stress activities.23 Quadriceps strength appears to determine the functional ability of the ACL deficient or operated limb to a great degree.24,25 Its weakness coincides with low functional performance26 and pathological gait pattern.27 In addition, functional improvement in ACL deficient athletes after training followed the same pattern as the strength of both the quadriceps and hamstrings.23,28 Likewise, increase in hamstring strength after functional exercise incorporating strengthening, stretching, and plyometric drills paralleled a decrease in peak landing forces, and hence safer landing.29 Hamstring strength has also been associated with the level of knee function10,30 and performance,31 and increasing the hamstring–quadriceps (H:Q) strength ratio has be come a rule in order to promote dynamic control of the ACL deficient knee.32,33 Even more, this improvement has been connected with the

Nonoperative Management of Anterior Cruciate Ligament Deficient Patients

IMPORTANCE OF THE HAMSTRINGS, ESPECIALLY IN SOCCER PLAYERS: OUR RESEARCH Our group recently investigated the connection of thigh muscle strength with the level of knee performance and the chronic stage of the injury in ACL deficient athletes. In order to reveal the net effect of ACL rupture on muscle strength, we examined amateur soccer players who abstained from structured rehabilitation in an attempt to exclude interference of exercise with the results. The first study focused on revealing a possible connection of quadriceps and hamstring strength deficits with the level of knee function determined by Lysholm score.30 Three groups of ACL deficient amateur soccer players were examined at different levels of knee function and were compared with a group of controls matched for the preinjury level of activity. The median Lysholm scores of the low, intermediate, and high knee functioning groups were 64.5, 76, and 86 points, respectively. Weakness depicted by the contrast to the healthy condition was significant in all cases and ranged from 19% to 35% according to the muscle or the patient group. Regarding the side-to-side deficit, these major muscle groups did not follow the same pattern. The strength asymmetry of the quadriceps was consistently significant even in the high functioning knees, being greater than 14%, in contrast to the hamstrings, which revealed acceptable symmetry within the normal levels (about 2% to less than 6%) at the high and intermediate knee function groups. Only the poorly functioning athletes had a significant 19% deficit (Fig. 7-1), which places hamstring strength asymmetry (H asymmetry) as a discriminating factor for knee functionality. The importance of assessing H asymmetry is highlighted in our recent study that examined different groups of amateur athletes involved in cutting and twisting sports such

40 35 Asymmetry (percent)

return to physical activity after ACL injury,34 and the strength of both thigh muscle groups reflects the functional improvement23,28 and the ability to return to physical activity.34 It appears that changes in muscle strength might be a global reflection of muscle properties, including neural changes.35 It seems that adequate strength ensures that a solid basis is built for other refined neuromuscular properties. In other words, adequate strength secures the proper background for the development of global muscle properties. Therefore, it appears that objective evaluation of strength has a valuable position in the functional assessment after ACL injury, and in combination with our findings, it could be suggested that therapeutic intervention should minimize strength weakness, which persists over time when not addressed.

7

30 25 20 15 10 5 0 Extension

Flexion

L1: High Lysholm L2: Intermediate L3: Low Lysholm Control FIG. 7-1 The percentage of extensor and flexor deficit in each experimental group formed according to the level of knee function (L1, L2, and L3: high, intermediate, and low Lysholm score, respectively) and the percentage of asymmetry in the control group (dominant versus nondominant knee).

as soccer, basketball, and handball at different times since ACL rupture.36 We tested the quadriceps and hamstring strength of 36 patients with unilateral ACL deficiency who were divided into three equal groups with mean times for chronicity of about 4, 11, and 57 months for short term, intermediate term, and long term, respectively. We investigated how the strength weakness evolved with time, using the strength of matched healthy controls as a baseline score. Additionally, we questioned whether the quadriceps’ and hamstrings' side-to-side asymmetry in strength would be consistently significant in all stages of chronicity. As in the previous study, significant weakness was evident in both muscles in all patient groups, ranging from 21% to 32%. Considering the side-to-side asymmetry of ACL deficient knees, the quadriceps deficit persisted through time, whereas the hamstrings regained symmetry even after 1 year without organized rehabilitation. Regarding the side-toside strength differences, they tended to lower with time, but in the case of quadriceps, they varied from 10% to 23%, whereas the hamstrings were significantly asymmetric only in the short-term group (14%) and acquired acceptable symmetry within 1 year postinjury (Fig. 7-2). Both studies show a trend for hamstring symmetry much more emphatically than the quadriceps as function improved or as the distance from the incidence of rupture increased. The strength asymmetry evident only in the worst-functioning group and the short-term group might reveal a natural compensatory reaction for ACL deficiency because no patients followed a structured rehabilitation 61

Anterior Cruciate Ligament Injury

† †

†

30 25 20

*

15 10 5 0 Extension

Flexion

*P < 0.05 compared with control †P < 0.01 compared with control P < 0.05 short term versus long term FIG. 7-2 The percentage of extensor and flexor deficit in each experimental group (injured versus intact knee: short term, intermediate, long term) and the percentage of asymmetry in the control group (dominant versus nondominant knee).

program. A supplementary finding of both studies was that the strength of the healthy side was considerably affected by the disuse, which was depicted on the mean reduction to the level of performance by a mean of 3 to 3.5 degrees Tegner. This raises the issues of ensuring not to neglect the intact side as well and counseling patients to maintain activity with safe exercise after injury. The quadriceps muscle is affected to a greater degree after ACL injury possibly because of (1) postinjury neural inhibition due to the loss of afferent feedback from ACL to gamma motor neurons37,38 and (2) the adaptation toward a “quadriceps avoidance gait” pattern39,40 to prevent anterior subluxation,41,42 which unloads the limb, promoting quadriceps weakness in ACL deficient patients.12 The greater atrophy of the quadriceps (10% versus 4%) reported even 1 year postinjury7 may also add to the explanation of their higher deficit compared with the hamstrings. In contrast, evidence exists that the hamstrings are recruited in weight-bearing activities in a subconscious attempt to counteract anterior shear forces.5,43 This stimulus might have assisted with the improvements in our patients. Evidence in the literature also supports the development of subtle electrophysiological modifications in ACL deficient patients that retune the hamstrings and preprogram their muscle activation strategies to optimize shear force dissipation during injured knee loading.14–16 In another study, we investigated the quality of muscle contraction when ACL deficient patients performed maximal exercise via the smoothness of the torque curve throughout knee extension and flexion.44 Our methodology comprised transformation of each torque-time curve pattern into the frequency domain (power spectrum) via fast Fourier 62

transform in order to quantify the smoothness of the isokinetic curve (Fig. 7-3). Each curve of biological signal that is not a perfect sine is actually the sum of other curves, and therefore it can be analyzed into its fundamental components. Our biological interpretation of this method is based on the notion that disturbed motion is generally connected to poor level of joint functionality. Irregular torque output has been connected to other pathologies such as anterior knee pain.45,46 In contrast, smoothness of torque generation is indicative of enhanced force control.47 The frequency contained at three levels of the total power of the signal (90%, 95%, and 99%) was calculated in order to exclude noise from the 100% power level but still include enough harmonics. Both extension and flexion isokinetic curves demonstrated increased irregularities as expressed by the higher-frequency contents by 18.8%, 10.6%, and 40.0% for knee extension and 49.5%, 24.5%, and 16.3% for knee flexion, according to the power level of assessment (Fig. 7-4). Although the results regarding quadriceps were expected on the basis of previous reports using different

300 Intact ACL

250 Torque (Nm)

Asymmetry (percent)

35

Short term Intermediate term Long term Control

200 150 100 50 0 0

0.2

0.4

0.6

A

0.8

1

1.2

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1.6

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0.2

0.4

0.6

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0 –20 Torque (Nm)

40

–40 –60 –80 –100 –120

ACL Intact

–140

B FIG. 7-3 A characteristic extensor (A) and flexor (B) isokinetic curve of the intact knee (blue line) and the anterior cruciate ligament (ACL) deficient knee (red line), demonstrating the side-to-side difference to the torque-time curve smoothness.

Nonoperative Management of Anterior Cruciate Ligament Deficient Patients 60 Power spectrum magnitude (dB)

250 200

Torque

7

150 100 50

50 40 30 20 10 0 –10 – 20

(4.12 Hz)

– 30 – 40

0 0

0.2

0.4

0.6

0.8

1

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10 15 20 25 30 35 40 45 50 Frequency

Time

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5

B

FIG. 7-4 Example of transformation of the isokinetic data of knee extension from the time domain (A) to frequency domain (B). The arrow shows the frequency content calculated for 99% of the signal power.

methodologies, the hamstrings' increased irregularity had not been reported elsewhere. This finding might be of functional importance and open a future area of investigation. The higher oscillations characterizing the isokinetic curve of the ACL deficient knee, which is expressed in increased frequency contents, may be attributed to mechanical and/or neuromuscular factors. Increased anterior gliding of the tibia during knee extension might account for the mechanical part. Quadriceps inhibition37,38 and poorly coordinated activation within the hamstrings43,48 must explain the neural aspects of abnormalities of mechanical output. This loss of smoothness in extension-flexion might be clinically important and should be investigated further. Quantification of irregularity of the extension-flexion curve is an innovative approach and could be a valuable tool in the assessment of ACL deficient knees.

REVIEW OF THE LITERATURE ON THE ROLE OF THE QUADRICEPS AND HAMSTRINGS IN ANTERIOR CRUCIATE LIGAMENT DEFICIENT KNEES The quadriceps is the muscle group suffering the most dramatic effects after ACL tear.19,30,36,49 For this reason, in addition to its functional importance for normal gait, it attracts most of the attention from clinicians and researchers. Quadriceps torque deficit is more than double hamstring deficit, which is attributed to its susceptibility for quick atrophy due to disuse10,18 and neural inhibition.37,38 Marked weakness of the quadriceps prevents the knee from functioning normally, and given that this weakness is exaggerated in many cases,30 it should be managed adequately. If the voluntary deficit measured via superimposed electrical burst to the maximal voluntary contraction exceeds 5%, treatment with electrical

stimulation effectively ameliorates loss of the quadriceps strength and should be implemented from the early stages.50 Although in ACL deficient knees there is no graft to be stressed due to the anterior instability of the tibia caused by quadriceps contraction particularly near extension,9,42,51 this might be harmful for other capsuloligamentous structures. In contrast, the hamstrings are properly located to counteract anterior tibial instability at flexion angles exceeding 30 degrees.52–54 However, doubts exist regarding the efficacy of the hamstrings to counterbalance shear loading of the knee,53,55 based on two concerns: first, whether the magnitude of the posteriorly directed muscle force is enough to counteract shear forces in the functionally more important knee angles near extension,41,54,56 and second, whether reflex activation of the hamstrings during abrupt perturbations of the knee is fast enough to develop tension in time with the peak external destabilizing moment.57,58 Considering the development of the properly directed stabilizing force, studies on cadavers,55,59 animals,54,60 and mathematical models53,61,62 support that beyond 30 degrees of knee flexion, the posteriorly directed vector of hamstring force becomes adequate in stabilizing the ACL deficient knee (Fig. 7-5). In addition, it should not be underestimated that even when the line of pool of the hamstrings is inefficient, co-contraction could increase joint stability due to joint compression63 and widening of the pressure distribution along the articular surfaces of the knee.64 Additionally, it has been reported that the hamstrings cause greater stiffness to the ACL deficient knee than they do to the intact knee.65 Regarding the question of the timely activation of the hamstrings, an overfocus on their reflex latency of 40 to 50 ms, which is a medium latency response,66–68 may be misleading in regard to their efficacy to prevent instability. Growing evidence in the literature supports the development of

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Anterior Cruciate Ligament Injury Research into the utility of functional knee bracing for ACL protection is inconclusive due to a great heterogeneity in the electromyography applied, experimental maneuvers, and characteristics of the participants. Moreover, whether the influence of braces on muscle function and proprioception is favorable for knee stability remains unclear. However, patients with torn ACLs who do not cope well with their injury and do not choose surgery might benefit from bracing.78

REHABILITATION A

B

FIG. 7-5 As the knee flexes from A to B, the anti-shear vector of the hamstring force (solid line) increases.

preprogrammed compensatory muscle activation strategies.12–16 These strategies suggest that subtle electrophysiological modifications of the subjects are implemented by deficient patients after ACL injury to optimize shear force dissipation during injured knee loading. Hence, feed-forward mechanisms can be adopted that initiate hamstring co-contraction during the expectation of knee loading, not only as a reflex response.13,16,69,70 Therefore the hamstrings should be well conditioned in order to have a greater potential to enhance knee stability.

BRACING IN ANTERIOR CRUCIATE LIGAMENT DEFICIENT PATIENTS: IS IT EFFECTIVE? The use of functional knee braces is a common practice for enhancing knee stability after rupture of the ACL or reconstruction, with contradictory opinions about their importance in knee unloading.71–73 A favorable change of firing pattern for the hamstrings was observed more often when ACL deficient patients performed single-leg landings wearing a brace69 and in skiers during periods of increased knee flexion.74 The greater biceps femoris activity was exhibited by the more unstable knees. Lam et al75 found that wearing a functional brace improved hamstring reflex responses in ACL deficient knees after fatigue induced by repeated extension and flexion against spring resistance. Although their protocol did not replicate a functional weight-bearing condition, it gives a potentially useful message that bracing in ACL deficient knees may enhance protection. Wojtys et al76 showed that braces can decrease anterior tibial translation by a large margin. In contrast, other findings have shown a slowing of hamstring muscle reaction times with bracing76 or decreased activation.71,77 64

Rehabilitation after ACL rupture is a multifactorial issue. However, the general goals consist of gaining good functional stability, optimizing the functional level, and minimizing the risk for reinjury.79 Interventions follow a general scheme depending on chronicity and are generally grouped into the acute phase focusing on range of motion, pain management, regaining ambulation, and retarding atrophy; the advanced phase, which aims to increase strength and endurance; and the return-to-play phase, with the final neuromuscular optimization of knee function.80 Progression from one stage to the other follows certain criteria, one being the achievement of adequate strength for the demands of each stage. Rehabilitation should aim at limiting thigh muscle weakness after ACL rupture, reducing the quadriceps sideto-side deficit to clinically acceptable levels, and assisting the hamstrings to regain strength faster. These benefits could enhance the natural reaction of the body against anterior knee instability. The effect of organized rehabilitation protocols on the time course of strength adaptations after ACL injury has yet to be examined. A promising research area is the investigation of whether early and intensive postinjury strengthening of the hamstrings will allow more ACL deficient patients to cope with their injury. Nevertheless, only a small fraction of ACL deficient athletes who choose not to have a reconstruction return to their previous level of exercise, and those who do so progress through rehabilitation through specific training and by achieving certain criteria.81 The majority follow a more conservative lifestyle attributed either to knee problems79 or to social reasons and fear of reinjury.82 Excessive atrophy and weakness of the quadriceps are evident in ACL deficient patients and, in cases of quadriceps inhibition, might not be reversible without electrical stimulation, which should commence from the early stages.38 Quadriceps activity potentially leads to knee instability, but it can be exercised safely either through a closed kinetic chain or in angles flexed more than 45 degrees. This deficit should not be neglected because it persists through time.36 Hamstring strength has been connected with the functional outcome of the ACL deficient30 and ACL

Nonoperative Management of Anterior Cruciate Ligament Deficient Patients reconstructed knee10 or the possibility of engaging in higher levels of sports participation.32 Strengthening of the hamstrings holds a key position in the conservative treatment of the ACL deficient knee,32,83 and it appears that strength training of a specific muscle also increases its coactivation level.84 A 3-month, high-resistance training program with four sets of 8 RM (repetitions maximum: load that permits the completion of only eight repetitions) performed 3 times per week may increase the capacity of the hamstrings to provide stability to the knee joint during fast extension.85 This improvement was expressed through a significantly elevated H eccentric:Q concentric ratio. As a rule, ACL rupture leads to a decrease in the level of physical activity, especially in those who were involved in cutting and twisting sports.86,87 ACL deficient athletes appear to reduce physical activity to 4 degrees Tegner from an initial 9 and 10 degrees.88 Characteristically, Lysholm et al3 reported that although the activity of 62% of their sample was higher than 7 degrees Tegner prior to ACL rupture, after the injury only 10% remained above this limit. Reduction of physical activity markedly affects the healthy side as well,30,36 complicating the return to high-demand activities. To counteract that, closed kinetic chain exercises with great hip flexion angles are an evidence-based method to re-educate coordination and physiological properties with safety, along with open chain single-joint exercise for more specific effects. Hip control is crucial for the control of knee rotation and proper lower limb alignment, but it is important to remember that the knee is not only directly interrelated with the hip joint but is also connected with the ankle joint. Rudolph et al89 found that coping patients partly relieved the ACL deficient knee by demonstrating a higher contribution of the ankle extensors to the total moment production of the lower limb. Likewise, hamstring tasks to control knee instability can be reinforced by synergists including the anterior tibialis, soleus,90,91 and muscles of the deep posterior compartment muscle group.90 Those synergists have the potential to control the anterior translation and internal rotation of the tibia. This occurs via their reverse action on the ankle and the subtalar joints during closed kinetic chain activities, when the foot is planted on the ground and subsequently the peripheral movement is restricted. Concerning the gastrocnemius, its origin above the knee joint complicates the effect of its action. Fleming et al 92 implanted the more precise and accurate differential variable reluctance transducer (DVRT)93,94 on the anteromedial bundle of the ACL and showed that isometric gastrocnemius muscle contraction strained the ACL within the last 15 degrees of knee extension. Additionally, gastrocnemius muscle contraction combined with quadriceps or hamstring muscle contraction increased the strain up to the last 30 degrees of flexion in comparison with isolated contractions of these muscles. This

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study ensured muscle specificity in contraction by applying transcutaneous electrical muscle stimulation in subjects under spinal anesthesia. However, there are studies indirectly showing that gastrocnemius contraction could stabilize the tibia under certain circumstances. O'Connor,95 using a twodimensional mathematical model, found that simultaneous contraction of the quadriceps, hamstrings, and gastrocnemius totally unloaded the ACL at 22 degrees of flexion. Kvist and Gullquist96 showed that when the gastrocnemius is coactivated with the quadriceps in a closed chain exercise (squatting) with the center of gravity over or posterior to the foot, joint compression is increased but anterior tibial translation is not. They also suggest that ACL deficient patients should enhance the spontaneous coactivation of quadriceps with certain neuromuscular training. However, Fleming et al97 questioned the safety of closed kinetic exercises, leaving the area still open for investigation. A safe compromise among those findings could be that isolated contractions of the gastrocnemius should be avoided after ACL rupture and their coactivation with other muscles in open chain exercise can be avoided by performing hamstring curls with the foot plantar flexed. Protective exercise for the ACL should be global and include exercises for the joints adjacent to the knee, and strengthening of those muscles could create a background for improvement of the overall muscle performance. Strengthening should combine open chain exercises for all lower limb joints, executed in a safe manner according to the current research, as well as closed chain activities. Generally, neuromuscular training with closed chain exercises appears beneficial when performed with caution and progressively, as it provides more sophisticated muscle interrelations that enhance safety but are still difficult to define.

SUMMARY ACL rupture deprives the knee of a major stabilizing structure, and therefore the role of the surrounding musculature becomes crucial for dynamic protection of the joint. The quadriceps suffer the greatest deficits in performance, which affects the normal lower limb kinematics and should be treated, even with the use of electrical stimulation if necessary. The hamstrings tend to recover earlier; this might be attributed to a natural reaction to promote stability. This trend should be facilitated and reinforced because it appears that neurophysiological adaptations include reprogramming of muscle activation, during which hamstrings are activated earlier in anticipation of perturbations. Even in knee angles in which the magnitude of force is small and inefficient to counterbalance anterior tibial subluxation, hamstrings contraction still has a stabilizing potential for the knee through joint 65

Anterior Cruciate Ligament Injury compression. Adequate strength levels provide the basis for further functional improvement during rehabilitation of ACL deficient knees. Organized and specific exercises should incorporate muscle strengthening, functional plyometric drills, and joint perturbations advancing in steps under certain criteria. The use of knee braces, although their degree of ACL deficient knee protection is still unclear, might help in poorly functioning patients.

References 1. Besier TF, Lloyd DG, Cochrane JL, et al. External loading of the knee joint during running and cutting maneuvers. Med Sci Sports Exerc 2001;33:1168–1175. 2. Scott SH, Winter DA. Internal forces of chronic running injury sites. Med Sci Sports Exerc 1990;22:357–369. 3. Lysholm M, Messner K. Sagittal plane translation of the tibia in anterior cruciate ligament-deficient knees during commonly used rehabilitation exercises. Scand J Med Sci Sports 1995;5:49–56. 4. Noyes FR, Matthews DS, Mooar PA, et al. The symptomatic anterior cruciate-deficient knee. J Bone Joint Surg Am 1983;65:163–174. 5. Solomonow M, Baratta R, Zhou BH, et al. The synergistic action of the anterior cruciate ligament and thigh muscles in maintaining joint stability. Am J Sports Med 1987;15:207–213. 6. Finsterbush A, Frankl U, Matan Y, et al. Secondary damage to the knee after isolated injury of the anterior cruciate ligament. Am J Sports Med 1990;18:475–479. 7. Gerber C, Hoppeler H, Claassen H, et al. The lower extremity musculature in chronic symptomatic instability of the anterior cruciate ligament. J Bone Joint Surg Am 1985;67:1034–1043. 8. Hogervorst T, Rijcken THP, Hart CPVD, et al. Abnormal bone scans in anterior cruciate ligament deficiency indicate structural and functional abnormalities. Knee Surg Sports Traumatol Arthrosc 2000;8:137–142. 9. Beynnon BD, Braden CF, Johnson RJ, et al. Quadriceps muscle contraction protects the anterior cruciate ligament during anterior tibial translation. Am J Sports Med 1995a;23:187–190. 10. Wojtys EM, Huston LJ. Neuromuscular performance in normal and anterior cruciate ligament-deficient lower extremities. Am J Sports Med 1994;22:89–104. 11. Georgoulis AD, Pappa L, Moebius U, et al. The presence of proprioceptive mechanoreceptors in the remnants of the ruptured ACL as a possible source of re-innervation of the ACL autograft. Knee Surg Sports Traumatol Arthrosc 2001;9:364–368. 12. Kalund S, Sinkjaer T, Arendt-Nielsen L, et al. Altered timing of hamstring muscle action in anterior cruciate ligament deficient patients. Am J Sports Med 1990;18:245–248. 13. Dyhre-Poulsen P, Simonsen EB, Voigt M. Dynamic control of muscle stiffness and H reflex modulation during hopping and jumping in man. J Physiol 1991;437:287–304. 14. DeMont RG, Lephart SM. Effect of sex on preactivation of the gastrocnemius and hamstring muscles. Br J Sports Med 2004;38:120–124. 15. Di Fabio RP, Graf B, Badke MB, et al. Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex. Exp Brain Res 1992;90:189–200. 16. McNair PJ, Marshall RN. Landing characteristics in subjects with normal and anterior cruciate ligament deficient knee joints. Arch Phys Med Rehab 1994;75:584–589. 17. Shelbourne KD, Johnson BC. Effects of patellar tendon width and preoperative quadriceps strength on strength return after anterior cruciate ligament reconstruction with ipsilateral bone-patellar tendonbone autograft. Am J Sports Med 2004;32:1474–1478.

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18. Wilk KE. Accelerated rehabilitation after anterior cruciate ligament reconstruction with central-third patellar tendon. In Brotzman SB, Wilk KE (eds). Clinical orthopaedic rehabilitation, ed 2. Philadelphia, 2003, Mosby, pp 288–289. 19. Keays SL, Bullock-Saxton J, Keays AC. Strength and function before and after anterior cruciate ligament reconstruction. Clin Orthop 2000;373:174–183. 20. Tibone JE, Antich TJ, Fanton GS, et al. Functional analysis of anterior cruciate ligament instability. Am J Sports Med 1986;14:276–284. 21. Rudolph KS, Axe MJ, Snyder-Mackler L. Dynamic stability after ACL injury: who can hop? Knee Surg Sports Traumatol Arthrosc 2000;8:262–269. 22. Murray SM, Warren RF, Otis JC, et al. Torque-velocity relationships of the knee extensor and flexor muscles in individuals sustaining injuries of the anterior cruciate ligament. Am J Sports Med 1984;12:436–440. 23. Patel RR, Hurwitz DE, Bush-Joseph CA, et al. Comparison of clinical and dynamic knee function in patients with anterior cruciate ligament deficiency. Am J Sports Med 2003;31:68–74. 24. Lund-Hansen H, Gannon J, Engebretsen L, et al. Isokinetic muscle performance in healthy female handball players and players with a unilateral anterior cruciate ligament reconstruction. Scand J Med Sci Sports 1996;6:172–175. 25. Lewek M, Rudolph K, Axe M, et al. The effect of insufficient quadriceps strength on gait after anterior cruciate ligament reconstruction. Clin Biomech 2002;17:56–63. 26. Gauffin H, Tropp H. Altered movement and muscular activation patterns during the one legged jump in patients with an old anterior cruciate ligament rupture. Am J Sports Med 1992;20:182–192. 27. Liu W, Maitland ME. The effect of hamstring muscle compensation for anterior laxity in the ACL-deficient knee during gait. J Biomech 2000;33:871–879. 28. Zatterstrom R, Friden T, Lindstrand A, et al. Rehabilitation following acute anterior cruciate ligament injuries—a 12-month follow-up of a randomized clinical trial. Scand J Med Sci Sports 2000;10:156–163. 29. Hole CD, Smith GH, Hammond J, et al. Dynamic control and conventional strength ratios of the quadriceps and hamstrings in subjects with anterior cruciate ligament deficiency. Ergonomics 2000;43:1603–1609. 30. Tsepis E, Vagenas G, Giakas G, et al. Hamstring weakness as an indicator of poor knee function in ACL-deficient patients. Knee Surg Sports Traumatol Arthrosc 2004a;12:22–29. 31. Vergis A, Hindriks M, Gillquist J. Sagittal plane translations of the knee in anterior cruciate deficient subjects and controls. Med Sci Sports Exerc 1997;29:1561–1566. 32. Giove TP, Sayers JM III, Kent BE, et al. Non-operative treatment in the torn anterior cruciate ligament. J Bone Joint Surg 1983;65A:184–192. 33. Walla DJ, Albright JP, McAuley E, et al. Hamstring control and the unstable anterior cruciate ligament-deficient knee. Am J Sports Med 1985;13:34–39. 34. Pincivero DM, Lephart SM, Karunakara RA. Reliability and precision of isokinetic strength and muscular endurance for the quadriceps and hamstrings. Int J Sports Med 1996;18:113–117. 35. Corcos DM, Slobodan J, Gottlieb GL. Electromyographic analysis of performance enhancement. In Zelaznik HN (ed). Advances in motor learning and control. Chicago, 1996, Human Kinetics, p 137. 36. Tsepis E, Vagenas G, Ristanis S, et al. Thigh muscle weakness in ACL-deficient knees persists without structured rehabilitation. Clin Orthop Rel Res 2006;450:211–218. 37. Konishi Y, Fukubayashi T, Takeshita D. Possible mechanism of quadriceps femoris weakness in patients with ruptured anterior cruciate ligament. Med Sci Sports Exerc 2002;34:1414–1418. 38. Snyder-Mackler L, Luca PF, Williams PR, et al. Reflex inhibition of the quadriceps femoris muscle after injury or reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1994;76:555–560. 39. Andriacchi T. Dynamics of pathological motion: applied to the anterior cruciate deficient knee. J Biomech 1990;23:99–105.

Nonoperative Management of Anterior Cruciate Ligament Deficient Patients 40. Wexler G, Hurwitz D, Bush-Joseph CA, et al. Functional gait adaptations in patients with anterior cruciate ligament deficiency over time. Clin Orthop Rel Res 1998;348:166–175. 41. Beynnon BD, Fleming BC, Johnson RJ, et al. Anterior cruciate ligament strain behavior during rehabilitation exercises in vivo. Am J Sports Med 1995b;23:24–34. 42. Hirokawa S, Solomonow M, Lu Y, et al. Anterior-posterior and rotational displacement of the tibia elicited by quadriceps contraction. Am J Sports Med 1992;20:299–306. 43. Tsuda E, Okamura Y, Otsuka H, et al. Direct evidence of the anterior cruciate ligament-hamstring reflex arc in humans. Am J Sports Med 2001;29:83–87. 44. Tsepis E, Giakas G, Vagenas G, et al. Frequency content asymmetry of the isokinetic curve between ACL deficient and healthy knee. J Biomech 2004b;37:857–864. 45. Dvir Z. Isokinetics of the knee muscles. In Dvir Z (ed). Isokinetics: muscle testing, interpretation, and clinical applications. New York, 1995, Churchill Livingstone, p 110. 46. Lysholm J. The relation between pain and torque in an isokinetic strength test of knee extension. Arthroscopy 1987;3:182–184. 47. Tracy BL, Enoka RM. Older adults are less steady during submaximal isometric contractions with the knee extensor muscles. J Appl Physiol 2002;92:1004–1012. 48. Boerboom AL, Hof AL, Halbertsma JPK, et al. A typical hamstrings electromyographic activity as a compensatory mechanism in anterior cruciate ligament deficiency. Knee Surg Sports Traumatol Arthrosc 2001;9:211–216. 49. Wojtys EM, Huston LJ. Longitudinal effects of anterior cruciate ligament injury and patellar tendon autograft reconstruction on neuromuscular performance. Am J Sports Med 2000;28:336–344. 50. Snyder-Mackler L, Delitto A, Bailey SL, et al. Strength of the quadriceps femoris muscle and functional recovery after reconstruction of the anterior cruciate ligament. A prospective, randomized clinical trial of electrical stimulation. J Bone Joint Surg Am 1995;77:1166–1173. 51. Nisell R, Ericson MO, Nemeth G, et al. Tibiofemoral joint forces during isokinetic knee extension. Am J Sports Med 1989;17:49–54. 52. More RC, Bryant TK, Neiman R, et al. Hamstrings—an anterior cruciate ligament protagonist. Am J Sports Med 1993;21:231–237. 53. Pandy M, Shelbourne KB. Dependence of cruciate-ligament loading on muscle forces and external load. J Biomech 1997;30:1015–1024. 54. Renstrom P, Arms SW, Stanwyck TS, et al. Strain within the anterior cruciate ligament during hamstring and quadriceps activity. Am J Sports Med 1986;14:83–86. 55. Markolf KL, O'Neill G, Jackson SR, et al. Effects of applied quadriceps and hamstrings muscle loads on forces in the anterior and posterior cruciate ligaments. Am J Sports Med 2004;32:1144–1149. 56. Kain CC, McCarthy JA, Arms S, et al. An in vivo analysis of the effect of transcutaneous electronical stimulation of the quadriceps and hamstrings in anterior cruciate ligament deformation. J Bone Joint Surg 1988;16:147–152. 57. Krogsgaard MR, Dyhre-Poulsen P, Fischer-Rasmussen T. Cruciate ligament reflexes. J Electromyogr Kinesiol 2002;12:177–182. 58. Shultz SJ, Perrin DH. Using surface electromyography to access sex differences in neuromuscular response characteristics. J Athletic Train 1999;34:165–176. 59. Li G, Rudy TW, Sakane MA, et al. The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL. J Biomech 1999;32:395–400. 60. Aune AK, Nordsletten L, Skjeldal S, et al. Hamstrings and gastrocnemius co-contraction protects the anterior cruciate ligament against failure: an in vivo study in the rat. J Orthop Res 1995;13:147–150. 61. Imran A, O'Connor JJ. Control of knee stability after ACL injury or repair: interaction between hamstrings contraction and tibial translation. Clin Biomech (Bristol, Avon) 1998;13:153–162. 62. Shelburne KB, Torry MR, Pandy MG. Effect of muscle compensation on knee instability during ACL-deficient gait. Med Sci Sports Exerc 2005;37:642–648.

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63. Steele JR, Brown JM. Effects of chronic anterior cruciate ligament deficiency on muscle activation patterns during an abrupt deceleration task. Clin Biomech 1999;14:247–257. 64. Baratta R, Solomonow M, Zhou BH, et al. Muscular coactivation: the role of the antagonist musculature in maintaining knee stability. Am J Sports Med 1988;16:113–122. 65. Jennings AG, Seedhom BB. The measurement of muscle stiffness in anterior cruciate injuries—an experiment revisited. Clin Biomech 1998;13:138–140. 66. Jennings AG, Seedhom BB. Proprioception in the knee and reflex hamstring contraction latency. J Bone Joint Surg Br 1994;76:491–494. 67. Beard DJ, Kyberd PJ, O'Connor JJ, et al. Reflex hamstring contraction latency in anterior cruciate ligament deficiency. J Orthop Res 1994;12:219–228. 68. Friemert B, Bumann-Melnyk M, Faist M, et al. Differentiation of hamstring short latency versus medium latency responses after tibia translation. Exp Brain Res 2005;160:1–9. 69. Smith J, Malanga GA, Yu B, et al. Effects of functional knee bracing on muscle-firing patterns about the chronic anterior cruciate ligamentdeficient knee. Arch Phys Med Rehab 2003;84:1680–1686. 70. Johansson H, Sjolander P, Sojka P. A sensory role for the cruciate ligaments. Clin Orthopaed 1991;268:161–178. 71. Ramsey DK, Wretenberg PF, Lamontagne M, et al. Electromyographic and biomechanic analysis of anterior cruciate ligament deficiency and functional knee bracing. Clin Biomech (Bristol, Avon) 2003;18:28–34. 72. DeVita P, Lassiter T Jr, Hortobagyi T, et al. Functional knee brace effects during walking in patients with anterior cruciate ligament reconstruction. Am J Sports Med 1998;26:778–784. 73. Vailas JC, Pink M. Biomechanical effects of functional knee bracing. Practical implications. Sports Med 1993;15:10–18. 74. Nemeth G, Lamontagne M, Tho K, et al. Electromyographic activity in expert downhill skiers using functional braces after anterior cruciate ligament injuries. Am J Sports Med 1997;25:635–641. 75. Lam RY, Ng GY, Chien EP. Does wearing a functional knee brace affect hamstring reflex time in subjects with anterior cruciate ligament deficiency during muscle fatigue? Arch Phys Med Rehabil 2002;83:1009–1012. 76. Wojtys EM, Kothari SU, Huston LJ. Anterior cruciate ligament functional brace use in sports. Am J Sports Med 1996;24:539–546. 77. Acierno SP, D'Ambrosia C, Solomonow M, et al. Electromyography and biomechanics of a dynamic knee brace for anterior cruciate ligament deficiency. Orthopaedics 1995;18:1101–1107. 78. Beynnon BD, Good L, Risberg MA. The effect of bracing on proprioception of knees with anterior cruciate ligament injury. J Orthop Sports Phys Ther 2002;32:11–15. 79. Kvist J. Rehabilitation following anterior cruciate ligament injury. Current recommendations for sports participation. Sports Med 2004;34:269–280. 80. Chmielewski TL, Mizner LR, Padamonski W, et al. Knee. In Kolt GS, Snyder-Mackler L (eds). Physical therapies in sport and exercise. St. Louis, 2003, Churchill Livingstone, pp. 386–389. 81. Chmielewski TL, Rudolph KS, Fitzgerald GK, et al. Biomechanical evidence supporting a differential response to acute ACL injury. Clin Biomech 2001;16:686–691. 82. Mikkelsen C, Werner S, Eriksson E. Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study. Knee Surg Sports Traumatol Arthrosc 2000;8:337–342. 83. Hagood S, Solomonow M, Baratta R, et al. The effect of joint velocity on the contribution of the antagonist musculature to knee stiffness and laxity. Am J Sports Med 1990;18:182–187. 84. Solomonow M, Krogsgaard M. Sensorimotor control of knee stability. A review. Scand J Med Sci Sports 2001;11:64–80. 85. Aagaard P, Simonsen EB, Trolle M, et al. Specificity of training velocity and training load on gains in isokinetic knee joint strength. Acta Physiol Scand 1996;156:123–129.

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Anterior Cruciate Ligament Injury 86. St Clair Gibson A, Lambert MI, Durandt JJ, et al. Quadriceps and hamstrings peak torque ratio changes in persons with chronic anterior cruciate ligament deficiency. J Orthop Sports Phys Ther 2000;7:418–427. 87. Bonamo JJ, Fay C, Firestone T. The conservative treatment of the anterior cruciate deficient knee. Am J Sports Med 1990;18:618–623. 88. Jorgensen U, Bak K, Ekstrand J, Scavenius M. Reconstruction of the anterior cruciate ligament with the iliotibial band autograft in patients with chronic knee instability. 2001;9:137–145. 89. Rudolph KS, Eastlack ME, Axe MJ, et al. Movement patterns after anterior cruciate ligament injury: a comparison of patients who compensate well for the injury and those who require operative stabilization. J Electromyogr Kinesiol 1998;8:349–362. 90. Nyland JA, Shapiro R, Caborn DN, et al. The effect of quadriceps femoris, hamstring, and placebo eccentric fatigue on knee and ankle dynamics during crossover cutting. J Orthop Sports Phys Ther 1997;25:171–184. 91. Chmielewski TL, Rudolph KS, Snyder-Mackler L. Development of dynamic knee stability after acute ACL injury. J Electromyogr Kinesiol 2002;12:267–274.

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92. Fleming BC, Renström PA, Ohlen G, et al. The gastrocnemius muscle is an antagonist of the anterior cruciate ligament. J Orthop Res 2001a;19:1178–1184. 93. Fleming BC, Beynnon BD: In vivo measurement of ligament/tendon strains and forces: a review. Ann Biomed Eng 2004;32:318–328. 94. Beynnon BD, Fleming BC: Anterior cruciate ligament strain in-vivo: a review of previous work. J Biomech 1998;31:519–525. 95. O'Connor JJ. Can muscle co-contraction protect knee ligaments after injury or repair? J Bone Joint Surg Br 1993;75B:41–48. 96. Kvist J, Gillquist J. Sagittal plane knee translation and electromyographic activity during closed and open kinetic chain exercises in anterior cruciate ligament-deficient patients and control subjects. Am J Sports Med 2001;29:72–82. 97. Fleming BC, Renström PA, Beynnon BD, et al. The effect of weightbearing and external loading on anterior cruciate ligament strain. J Biomech 2001b;34:163–170.

Arthrosis Following Anterior Cruciate Ligament Tear and Reconstruction INTRODUCTION The development of degenerative changes within the knee following anterior cruciate ligament (ACL) injury is well recognized. However, defining the exact incidence of arthrosis following an ACL injury or after reconstruction of the ACL is a challenge for several reasons. Long-term clinical follow-up studies are difficult to perform because most patients presenting with an ACL injury are young and many will change geographical location in the years following surgery. Outcome studies with long-term follow-up periods tend to have a large number of patients lost to follow-up for this reason. Furthermore, the group of patients with these injuries is heterogenous, with widely varying ages, preinjury levels of activity, and different expectations following treatment. ACL tears may occur in isolation, but a significant proportion is associated with collateral ligament injuries and concomitant or subsequent meniscal tears, which may also influence the development of degenerative change. In addition to these considerations, some patients may have a previous history of knee injury or surgery and may already have significant degenerative changes within the knee at the time the ACL injury is sustained. Although most ACL reconstructions are carried out using either hamstring or patellar tendon autografts, there is wide variation in the surgical techniques used to prepare and anchor grafts, which may also influence

development of osteoarthritis (OA). The timing of surgical reconstruction after injury may also be of considerable importance. Access to expert orthopaedic opinion and treatment varies considerably with geographical location, and in some areas the duration from injury to surgery may be prolonged. In this chapter we consider the existing evidence linking ACL injury and treatment to subsequent development of OA.

8

CHAPTER

Nicholas E. Ohly John F. Keating

PATHOPHYSIOLOGY OF OSTEOARTHRITIS FOLLOWING ANTERIOR CRUCIATE LIGAMENT INJURY Previous studies have shown that restoring knee stability through ACL reconstruction does not necessarily decrease the incidence of posttraumatic OA.1,2 It therefore follows that other mechanisms, rather than the initial mechanical disturbance of stability at the time of injury, may be responsible for the development of OA, both in the chronic ACL deficient knee and in the reconstructed knee. Several biochemical mechanisms have been proposed. It has been shown that an early increase in the proteoglycan content of articular cartilage adjacent to the torn ligament occurs following ACL rupture.3 Other studies4,5 have shown an increase in collagenase activity leading to increased denaturation and loss of type II collagen in the articular cartilage of the knee

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Anterior Cruciate Ligament Injury following injury. These changes are also seen in the knee with idiopathic OA. Intraarticular pro-inflammatory cytokines are also increased immediately after ACL rupture.6,7 These include interleukins (IL) -1, -6, and -8, tumor necrosis factor alpha (TNF-a), and keratan sulfate. Of note, IL-1 (in both its alpha and beta forms) and TNF-a have direct chondrodestructive effects independent of their inflammatory properties. These cytokines are present in higher concentrations with more severe chondral damage, and levels fall gradually beginning approximately 3 months postinjury. Granulocytemacrophage colony-stimulating factor (GM-CSF) concentrations are initially normal but become grossly elevated beginning approximately 3 months postinjury. Conversely, the chondroprotective cytokine IL-1Ra concentration decreases with increasing severity of chondral damage and with chronic ACL deficiency. These findings suggest the existence of important contributory biochemical factors in the development of OA in the ACL deficient knee. Elevated intraarticular concentrations of several cytokines are present during the acute inflammation following ACL rupture, and this inflammation subsides but does not completely resolve in the subacute and chronic phases postinjury. Instead, a potentially chondrodestructive cytokine imbalance persists that can eventually lead to OA. It has been shown that ligamentous knee injury is strongly associated with bone bruising.8 Magnetic resonance imaging (MRI) scans performed acutely following ACL rupture have shown occult subchondral lesions in 85% of patients, mainly involving the lateral femoral condyle and lateral tibial plateau.9 Although the majority of these lesions resolved with time, permanent chondral damage is known to have occurred in some lesions. Histological analysis of these bone bruises has shown associated areas of chondrocyte degeneration and necrotic osteocytes, which suggests that significant damage to the articular cartilage is sustained at the time of injury.10 Following ACL reconstruction, further factors may play an additional role in the development of arthrosis. It has been shown that pretensioning the graft can cause changes in joint biomechanics that may lead to arthrosis in the long term.11,12 Shortening of the patellar tendon may occur after patellar tendon autograft, which has been shown to lead to patellofemoral arthrosis and a worse functional outcome, both of which are directly associated with the degree of shortening of the patellar tendon.13 Any intraarticular damage that requires treatment with meniscectomy will diminish the joint contact surface area and increase the stress on the tibia.14 The resultant increased stress on the knee joint has been shown to accelerate the development of OA.15 70

NATURAL HISTORY OF THE UNTREATED ANTERIOR CRUCIATE LIGAMENT DEFICIENT KNEE The development of arthrosis following ACL rupture is widely recognized,16,17 and in a review by Gillquist and Messner18 it was concluded that in the long term (i.e., 10 to 20 years), as many as 70% of all ACL deficient knees had radiological signs of arthrosis, although clinical symptoms of knee arthritis were infrequent. Segawa et al19 found radiographic changes of OA in 63% of patients who were followed for 12 years after a conservatively treated ACL rupture. The main risk factor for arthrosis was shown to be meniscectomy, in combination with the risk factors for primary OA, such as increased age at time of injury, increased level of sports activity, obesity, and OA of the contralateral knee. In a study of patients with symptomatic knee OA, 22.8% had complete ACL rupture identified at MRI, compared with 2.7% of controls.20 Patients with OA in the presence of an ACL rupture had more severe radiological OA. A cohort of female soccer players in Sweden was assessed 12 years after a known ACL injury, and although radiographic evidence of OA was seen in 82%, there was no difference in the incidence of OA between those ACL injuries treated nonoperatively (38%) and those treated with reconstruction, and the same proportion (75%) of those without radiographic OA had knee symptoms.2 Comparable results were seen in a similar study of male soccer players in Sweden 14 years following a known ACL injury.21 In children and adolescents with ACL rupture, nonoperative treatment is often favored to avoid drilling surgical tunnels across physeal growth plates. However, it has been shown that ACL injuries treated nonoperatively in this age group are likely to develop instability and poor function, with development of radiological signs of degeneration in almost half of children.22 Subsequent studies have shown that ACL reconstruction can be safely undertaken in adolescents nearing skeletal maturity.23 It has not yet been proven that this can be safely performed in very young children with opened physes. Despite this evidence, some studies challenge the concept that ACL tears are inextricably linked to development of arthritis. It has been shown that in older patients (40 to 60 years old) with an ACL rupture treated nonoperatively, 87% had little or no radiographic changes at a mean of 7 years postinjury.24 In 46 young recreational athletes followed up at an average of 5 years following conservative treatment of an ACL tear diagnosed at arthroscopy, only 17.4% had mild radiographic osteoarthritic changes, and only one patient (2.2%) was symptomatic.25

Arthrosis Following Anterior Cruciate Ligament Tear and Reconstruction

ARTHROSIS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION With the knowledge that ACL tears are associated with an increased risk of OA, it would seem reasonable to assume that ACL reconstruction would play a useful role in prevention of arthrosis in the long term. The difficulties in implementing large long-term follow-up studies following ACL reconstruction have already been mentioned. Table 8-1 summarizes the recent literature that has evaluated the incidence of arthrosis following ACL reconstruction. Analysis of these studies clearly suggests that surgical reconstruction of the ligament does not prevent the development of radiological OA. A meta-analysis by Lohmander and Roos26 found no evidence that ACL reconstruction slowed the progression of arthrosis following ACL rupture, and it does not seem that ACL reconstruction reduces the clinical symptoms of OA in the long term.2 However, it is noteworthy that most authors have found the majority of patients to be essentially asymptomatic at follow-up, regardless of the radiological changes, which are often mild. Clearly a spectrum of joint changes exists, with many patients demonstrating minimal radiographic change and few clinical symptoms, although unfortunately a minority will go on to have symptomatic arthrosis (Fig. 8-1). As with conservatively managed ACL tears, the major risk factor associated with the development of OA is meniscal damage27 and the need for meniscal resection at the time of

8

surgery.28–35 Some authors maintain that chondral damage is of more importance than medial meniscal tears, which in turn are more significant than lateral meniscal tears in the development of OA.34 However, even in the absence of chondral damage or meniscal injury, early mild degenerative changes may occur after successful ACL reconstruction.36 Other risk factors appear to be female gender and age older than 30 years,36,37 presence of persistent pivot shift following reconstruction,32 bone–patellar tendon–bone autograft compared with hamstring autograft,38,39 time to surgery,27,33,40 synthetic graft material,37,41 and maintenance of high levels of sporting activity after surgery.42 Surgery within 12 months of injury40,42 appears to reduce the incidence of arthrosis. There does not appear to be any benefit to surgery earlier than 3 months postinjury.43 Anteroposterior (AP) instability post reconstruction does not appear to be a risk.36,32 Looking at the most up-to-date studies that have followed patients undergoing ACL reconstruction using modern graft materials, it appears that the rate of radiographic degenerative changes is between 4% and 47% between 5 and 10 years of follow-up. This figure has been shown to rise as high as 100% following ACL reconstruction with a total meniscectomy.35 It has even been reported that the rate of degenerative change is higher in the reconstructed knee compared with the chronic ACL deficient knee.1 This is probably due to the fact that those patients who have symptomatic instability and require ACL reconstruction

FIG. 8-1 Anteroposterior (AP) (A) and lateral (B) radiographs of the knee of a man who underwent an anterior cruciate ligament (ACL) reconstruction associated with a medial meniscectomy 11 years previously. The initial femoral tunnel was too anterior. The graft was revised, but the patient presented with symptomatic arthritis at age 34 years.

71

72

Anterior Cruciate Ligament Injury

TABLE 8-1 Summary of Studies Reporting Results Following Anterior Cruciate Ligament (ACL) Reconstruction Author

Year Study Size

Type of ACL Follow-up Graft

(Mean

Incidence of Radiographic OA

Incidence of Symptomatic OA

Those who had PM had more medial compartment degeneration compared

More pain experienced by those following PM

(Imaging Modality)

Age) Aglietti 28

et al

Asano et al36 Deehan et al42 Hart et al29

1994 N ¼ 57

BPTB

4.6 years (XR)

(NA) 2004 N ¼ 105

with those who had meniscal repair or normal menisci NA

(NA) 2000 N ¼ 80

BPTB

3 months

100% (significant deterioration on all articular surfaces except lateral femoral

(arthroscopy)

condyle)

5 years (XR)

3% abnormal XR, all patients had normal articular cartilage and menisci at time 90% rated knee as subjectively normal or nearly normal

(25 years) 2005 N ¼ 31

NA

of surgery, 75% had surgery within 3 months of injury BPTB

10 years (SPECT) 7% (menisci intact), 34% (PM)

7% (menisci intact), 13% (PM)

BPTB

10.7 years (XR)

19% PF joint space narrowing, 15% medial compartment narrowing, 25%

84% normal or nearly normal knees on subjective

lateral compartment narrowing

assessment

29.7% (radiographic OA), higher incidence with delay to reconstruction and

83.7% subjectively normal or nearly normal knees

(27.8 years) Hertel et al30

2005 N ¼ 95 (42.2 years)

Jager et al27 2003 N ¼ 74

BPTB

10 years (XR)

(NA) Jarvela et al13 Jomha et al31 Jonsson et al32

2001 N ¼ 100

with meniscal injury BPTB

7 years (XR)

(31 years) 1999 N ¼ 53

BPTB

7 years (XR)

(NA) 2004 N ¼ 63

53% had no PFOA, 34% had mild PFOA, 13% had moderate or severe PFOA;

54% with moderate or severe radiological PFOA scored

tibiofemoral joint arthrosis was uncommon (no/mild changes in >95%)

knee as subjectively abnormal or severely abnormal

Chronic ACL deficiency predisposed to early OA, even with intact menisci prior NA to reconstruction; more severe changes in those undergoing PM

QT/PT

(NA)

2 and 5–9 years Positive pivot shift correlated with increased uptake on scintigraphy and

Positive pivot shift correlated with inferior subjective

(XR bone

higher incidence of OA

functional outcome 2 years after surgery

88% XR changes following total/PM, 12% XR changes following meniscal

Amount of pain poorly correlated with radiographic

repair, 3% with normal menisci had XR changes

changes

83% of total had XR changes

86% unacceptable knee stability and function

scintigraphy) Lynch et al33 Maletius et al

37

1983 N ¼ 227

ITB

3.8 years (XR)

(20.1) 1997 N ¼ 52

Dacron

9 years (XR)

(NA) continued

TABLE 8-1 Summary of Studies Reporting Results Following Anterior Cruciate Ligament (ACL) Reconstruction—Cont'd Author

Year Study Size

Type of ACL Follow-up Graft

(Mean

Incidence of Radiographic OA

Incidence of Symptomatic OA

(Imaging Modality)

Age) Murray and Macnicol

41

2004 N ¼ 18

LK

13.3 years (XR)

100%

Overall poor functional outcome for all patients

BPTB (90)

5 years (XR)

4% with hamstring, 18% with BPTB

Both groups had good clinical outcome at 5 years.

7 years (XR)

14% with hamstring, 45% with BPTB

Both groups had good clinical outcome at 7 years.

7.2 years (XR)

97% patients with no meniscectomy or articular cartilage damage had normal 87% of knees with normal cartilage, and 64.4% of knees

(28.4 years)

Pinczewski 38

et al

2002 N ¼ 180 (NA)

versus hamstring (90)

Roe et al39

2005 N ¼ 180 (NA)

BPTB (90) versus hamstring

Shelbourne et al34

Wu et al

35

2000 N ¼ 482

NA

(22.4

or near normal XR; 23–25% with total/PM of medial or both menisci had

following partial/total meniscectomy rated knee as

years)

abnormal or severely abnormal XR

subjectively normal or nearly normal

92% with normal/repaired menisci had normal XR; 100% following total

Subjective functional outcome worse with increasing

meniscectomy had radiographic OA

amounts of meniscus resected

2002 N ¼ 63 (24 years)

BPTB

10.4 years (XR)

BPTB, Bone–patellar tendon–bone; ITB, iliotibial band; LK, Leeds-Keio polyester ligament; NA, not available; OA, osteoarthritis; PF, patellofemoral compartment; PM, partial meniscectomy; QT/PT, quadriceps tendon–patellar tendon strip augmented with a polypropylene braid; SPECT, single-photon emission computerized tomography; XR, plain radiographs.

Arthrosis Following Anterior Cruciate Ligament Tear and Reconstruction

(90)

8

73

Anterior Cruciate Ligament Injury are more likely to have concomitant meniscal and/or chondral damage predisposing to the development of OA. By comparison, those patients with normal articular cartilage and menisci can often be satisfactorily managed conservatively. In our own study40 we investigated the relationship of time from injury to surgery on the incidence of meniscal tears and degenerative change. We evaluated 183 patients who underwent ACL reconstruction for isolated ACL tears using a quadruple hamstring graft. An arthroscopically assisted single-incision technique was used. Patients were divided into an early group (surgery within 12 months of injury) and a late group (surgery more than 12 months from injury). The late group was also subdivided into four groups of 12-month periods ranging from 1 year to more than 4 years after injury. There was a significantly higher incidence of meniscal tears in patients undergoing reconstruction after 12 months compared with those in the early group (71.2% versus 41.7%, P < 0.001) (Fig. 8-2). This was due to a large increase in medial meniscal tears in the late group. The incidence of lateral meniscal tears remained relatively unchanged with time. This may indicate that lateral meniscal tears occur at the time of ACL injury or very early after injury, whereas the majority of medial meniscal tears are acquired after the initial ACL tear. The increase in medial meniscal tears after 12 months probably correlates with an attempted return to preinjury levels of sporting activity. The data are consistent with development of knee instability associated with a return to sport, with increased torsional and shear forces resulting in acquired medial meniscal injuries and acceleration of degenerative change in the knee. We also found an increased incidence of degenerative change in the late group (31.3% versus 10.7%, P < 0.001) (Fig. 8-3), even though the majority of patients in both

Meniscal Pathology 100% 90%

Type of meniscal tear

80% 70% 60% 50%

Both

40%

Lateral

30%

Medial

20%

None

10% 0%

0–12

⬎12

Time to surgery (months) FIG. 8-2 Percentage of patients with meniscal pathology undergoing surgery 0–12 months after injury or more than 12 months after injury.

74

Degenerative Change 100% 90%

Grade of degenerative change

80% 70% 60% 50%

4

40%

3

30%

2

20% 1

10% 0%

0 0–12

⬎12

Time to surgery (months) FIG. 8-3 Incidence of degenerative change found at surgery 0–12 months and more than 12 months after injury.

groups had no degenerative change at all. The findings in the study indicate that reconstruction carried out within 1 year of injury is associated with a very low incidence of degenerative change. It remains to be seen whether an ACL reconstruction carried out at this stage confers a longer-term benefit in prevention of late degenerative change. In a recent study44 using modern reconstruction techniques with a hamstring autograft, the reported incidence of significant radiographic degenerative change at 2- to 8-years follow-up was only 4%, and these occurred in patients who had undergone meniscectomy. It is possible, therefore, that early reconstruction carried out in the presence of intact menisci may carry a more favorable prognosis with a lower incidence of arthrosis in the longer term.

CONCLUSION The development of arthrosis is a well-recognized complication following ACL rupture. The ACL injury itself is unlikely to be the sole causative mechanism, and initial chondral damage at the time of injury combined with various biochemical mediators may also be implicated. Meniscal damage, either directly at the time of injury or subsequent to chronic ACL deficiency, also plays a key role in the development of arthrosis. It is well recognized that the untreated ACL deficient knee has an increased risk of developing degenerative change. However, there is evidence to show that a significant number of patients also develop radiographic signs of arthrosis following ACL reconstruction. Despite this, the majority of ACL reconstructed patients have a very satisfactory functional outcome. The radiographic appearances are usually minimal, and patients are essentially asymptomatic despite these early degenerative changes. Several problems lie in meaningfully interpreting the literature on outcomes following ACL reconstruction. Study

Arthrosis Following Anterior Cruciate Ligament Tear and Reconstruction cohorts vary widely in terms of age, level of sports activity, outcome measures, and duration of follow-up. All recent studies have suboptimal follow-up rates, none of which was longer than 10 years. Most studies in the literature have looked at patients who have undergone ACL reconstruction using bone–patellar tendon–bone autograft, although hamstring autografts are now a popular choice. However, there is no sound evidence linking graft choice to the rate of post ACL reconstruction arthrosis. Although there is no definite evidence that ACL reconstruction prevents arthrosis in the long term, the literature indicates that chronic ACL deficiency and meniscal tears are the most important factors associated with the development of degenerative change. Delays to reconstruction for periods of longer than 12 months are associated with a greater risk of meniscal tears and degeneration. The evidence also suggests that early reconstruction of the ACL within 12 months of injury minimizes the rate of meniscal tears and consequently should lead to lower rates of arthrosis. We would advocate undertaking surgery within this timeframe. Furthermore, we would also recommend that every effort be made to repair meniscal injuries, as the loss of meniscal tissue is a major risk factor in post-reconstruction arthrosis. The most recent studies seem to indicate that early ACL reconstruction in knees with a normal articular surface and intact menisci will delay and may even prevent the development of arthrosis. More evidence from clinical studies with longer-term follow-up is required to support this view.

References 1. Daniel DM, Stone ML, Dobson BE, et al. Fate of the ACL-injured patient. A prospective outcome study. Am J Sports Med 1994;22:632–644. 2. Lohmander LS, Ostenberg A, Englund M, et al. High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 2004;50:3145–3152. 3. Nelson F, Billinghurst RC, Pidoux I, et al. Early post-traumatic osteoarthritis-like changes in human articular cartilage following rupture of the anterior cruciate ligament. Osteoarthritis Cartilage 2006;14:114–119. 4. Price JS, Till SH, Bickerstaff DR, et al. Degradation of cartilage type II collagen precedes the onset of osteoarthritis following anterior cruciate ligament rupture. Arthritis Rheum 1999;42:2390–2398. 5. Lohmander LS, Atley LM, Pietka TA, et al. The release of cross-linked peptides from type II collagen into human synovial fluid is increased soon after injury and in osteoarthritis. Arthritis Rheum 2003;48:3130–3139. 6. Cameron M, Buchgraber A, Passler H, et al. The natural history of the anterior cruciate ligament-deficient knee. Changes in synovial fluid cytokine and keratan sulfate concentrations. Am J Sports Med 1997;25:751–754. 7. Marks PH, Donaldson ML. Inflammatory cytokine profiles associated with chondral damage in the anterior cruciate ligament-deficient knee. Arthroscopy 2005;21:1342–1347. 8. Bretlau T, Tuxoe J, Larsen L, et al. Bone bruise in the acutely injured knee. Knee Surg Sports Traumatol Arthrosc 2002;10:96–101. 9. Rosen MA, Jackson DW, Berger PE. Occult osseous lesions documented by magnetic resonance imaging associated with anterior cruciate ligament ruptures. Arthroscopy 1991;7:45–51.

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10. Johnson DL, Urban WP, Jr, Caborn DN, et al. Articular cartilage changes seen with magnetic resonance imaging-detected bone bruises associated with acute anterior cruciate ligament rupture. Am J Sports Med 1998;26:409–414. 11. Good L, Askew MJ, Boom A. Kinematic in vitro comparison between the normal knee and two techniques for reconstruction of the anterior cruciate ligament. Clin Biomech 1993;8:243–249. 12. Heerwaarden van RJ, Stellinga D, Frudiger AJ. Effect of pretension on reconstructions of the anterior cruciate ligament with a Dacron prosthesis. A retrospective study. Knee Surg Sports Traumatol Arthrosc 1996;3:202–208. 13. Jarvela T, Paakkala T, Kannus P, et al. The incidence of patellofemoral osteoarthritis and associated findings 7 years after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18–24. 14. Fukubayashi T, Kurosawa H. The contact area and pressure distribution pattern of the knee: a study of normal and osteoarthrotic knee joints. Acta Orthop Scand 1980;51:871–879. 15. Englund M, Lohmander LS. Risk factors for symptomatic knee osteoarthritis fifteen to twenty-two years after meniscectomy. Arthritis Rheum 2004;50:2811–2819. 16. Kannus P, Jarvinen M. Conservatively treated tears of the anterior cruciate ligament. Long-term results. J Bone Joint Surg Am 1987;69:1007–1012. 17. Roos H, Adalberth T, Dahlberg L, et al. Osteoarthritis of the knee after injury to the anterior cruciate ligament or meniscus: the influence of time and age. Osteoarthritis Cartilage 1995;3:261–267. 18. Gillquist J, Messner K. Anterior cruciate ligament reconstruction and the long-term incidence of gonarthrosis. Sports Med 1999;27:143–156. 19. Segawa H, Omori G, Koga Y. Long-term results of non-operative treatment of anterior cruciate ligament injury. Knee 2001;8:5–11. 20. Hill CL, Seo GS, Gale D, et al. Cruciate ligament integrity in osteoarthritis of the knee. Arthritis Rheum 2005;52:794–799. 21. von Porat A, Roos EM, Roos H. High prevalence of osteoarthritis 14 years after an anterior cruciate ligament tear in male soccer players: a study of radiographic and patient relevant outcomes. Ann Rheum Dis 2004;63:269–273. 22. Aichroth PM, Patel DV, Zorrilla P. The natural history and treatment of rupture of the anterior cruciate ligament in children and adolescents. A prospective review. J Bone Joint Surg Br 2002;84:38–41. 23. Aronowitz ER, Ganley TJ, Goode JR, et al. Anterior cruciate ligament reconstruction in adolescents with open physes. Am J Sports Med 2000;28:168–175. 24. Ciccotti MG, Lombardo SJ, Nonweiler B, et al. Non-operative treatment of ruptures of the anterior cruciate ligament in middle-aged patients. Results after long-term follow-up. J Bone Joint Surg Am 1994;76:1315–1321. 25. Shirakura K, Terauchi M, Kizuki S, et al. The natural history of untreated anterior cruciate tears in recreational athletes. Clin Orthop Relat Res 1995;317:227–236. 26. Lohmander LS, Roos H. Knee ligament injury, surgery and osteoarthrosis. Truth or consequences? Acta Orthop Scand 1994;65:605–609. 27. Jager A, Welsch F, Braune C, et al. Ten year follow-up after single incision anterior cruciate ligament reconstruction using patellar tendon autograft. Z Orthop Ihre Grenzgeb 2003;141:42–47. 28. Aglietti P, Zaccherotti G, De Biase P, et al. A comparison between medial meniscus repair, partial meniscectomy, and normal meniscus in anterior cruciate ligament reconstructed knees. Clin Orthop Relat Res 1994;307:165–173. 29. Hart AJ, Buscombe J, Malone A, et al. Assessment of osteoarthritis after reconstruction of the anterior cruciate ligament: a study using single-photon emission computed tomography at ten years. J Bone Joint Surg Br 2005;87:1483–1487. 30. Hertel P, Behrend H, Cierpinski T, et al. ACL reconstruction using bone-patellar tendon-bone press-fit fixation: 10-year clinical results. Knee Surg Sports Traumatol Arthrosc 2005;13:248–255.

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Anterior Cruciate Ligament Injury 31. Jomha NM, Borton DC, Clingeleffer AJ, et al. Long-term osteoarthritic changes in anterior cruciate ligament reconstructed knees. Clin Orthop Relat Res 1999;358:188–193. 32. Jonsson H, Riklund-Ahlstrom K, Lind J. Positive pivot shift after ACL reconstruction predicts later osteoarthrosis: 63 patients followed 5–9 years after surgery. Acta Orthop Scand 2004;75:594–599. 33. Lynch MA, Henning CE, Glick KR, Jr. Knee joint surface changes. Long-term follow-up meniscus tear treatment in stable anterior cruciate ligament reconstructions. Clin Orthop Relat Res 1983;172:148–153. 34. Shelbourne KD, Gray T. Results of anterior cruciate ligament reconstruction based on meniscus and articular cartilage status at the time of surgery. Five- to fifteen-year evaluations. Am J Sports Med 2000;28:446–452. 35. Wu WH, Hackett T, Richmond JC. Effects of meniscal and articular surface status on knee stability, function, and symptoms after anterior cruciate ligament reconstruction: a long-term prospective study. Am J Sports Med 2002;30:845–850. 36. Asano H, Muneta T, Ikeda H, et al. Arthroscopic evaluation of the articular cartilage after anterior cruciate ligament reconstruction: a short-term prospective study of 105 patients. Arthroscopy 2004;20:474–481. 37. Maletius W, Gillquist J. Long-term results of anterior cruciate ligament reconstruction with a Dacron prosthesis. The frequency of osteoarthritis after seven to eleven years. Am J Sports Med 1997;25:288–293.

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38. Pinczewski LA, Deehan DJ, Salmon LJ, et al. A five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:523–536. 39. Roe J, Pinczewski LA, Russell VJ, et al. A 7-year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction: differences and similarities. Am J Sports Med 2005;33:1337–1345. 40. Church S, Keating JF. Reconstruction of the anterior cruciate ligament. Timing of surgery and the incidence of meniscal tears and degenerative change. J Bone Joint Surg Br 2005;87:1639–1642. 41. Murray AW, Macnicol MF. 10–16 year results of Leeds-Keio anterior cruciate ligament reconstruction. Knee 2004;11:9–14. 42. Deehan DJ, Salmon LJ, Webb VJ, et al. Endoscopic reconstruction of the anterior cruciate ligament with an ipsilateral patellar tendon autograft. A prospective longitudinal five-year study. J Bone Joint Surg Br 2000;82:984–991. 43. Meighan A, Keating JF, Will E. Early versus delayed reconstruction for acute ACL tears: a prospective randomised trial. J Bone Joint Surg Br 2003;85:521–524. 44. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146.

The Economics of Anterior Cruciate Ligament Reconstruction BACKGROUND With more than 100,000 anterior cruciate ligament reconstructions (ACLRs) now performed yearly in the United States, total ACLR costs exceed half a billion dollars annually. In this chapter the major component costs of ACLR will be analyzed along with institutional reimbursement levels. Finally, the effect of current trends and emerging technology as they affect ACLR cost will be discussed.

PURPOSE The purpose of this chapter is to help surgeons understand the economic implications of their choices for resource utilization in ACLR. All of the relevant cost variables discussed in this chapter are under surgeon control. These choices are always made to maximize patient outcomes. However, it is also useful to understand the economic impact of these choices. Limited resources coupled with increased demand and increasingly expensive technology may force the surgeon to make increasingly difficult decisions in the future in this regard.

WHOSE COSTS ARE BEING CONSIDERED? ACLR costs can be considered from both macro- and microeconomic perspectives. The macroeconomic perspective deals with how many

societal dollars are being spent by patients and third-party payers on ACLR. From this perspective the goal is to spend the minimal amount consistent with high-quality care out of the finite healthcare dollars available. The microeconomic perspective in this context deals with the institution (the hospital or surgicenter) where the surgery is performed. The goal from this perspective is to balance costs with payments so that losses are avoided. Excessive macroeconomic costs can lead to lower institutional reimbursements and disallowal of charges (e.g., as have recently happened with refusals to pay for mechanized cold units after ACLR). It can also lead to reduced surgeon reimbursements to both save money and attempt to provide a disincentive to surgeons performing the procedure. Excessive microeconomic institutional costs relative to payments can also lead to controls on choices by surgical facilities to reduce those costs. The answer to both macro- and microeconomic cost containment is for utilization choices to be soundly grounded in patient outcomes. Thus, by constraining excessive costs, the procedure is less likely to become a target for cost cuts. Furthermore, if cuts in necessary services are proposed, the surgeon, as the patient advocate, is better able to justify the necessity of the provided service.

9

CHAPTER

Chadwick C. Prodromos Julie Rogowski Brian T. Joyce

SOURCES OF COST INFORMATION The information presented here was obtained by personal communication between the authors and various institutions and companies. The 79

Anterior Cruciate Ligament Reconstruction numbers are only approximations and are skewed toward the Chicago area and the U.S. healthcare system. Some of the information was provided only on condition of confidentiality. Specific companies or devices have not been listed partially for this reason and partially because the numbers are subject to great variation by region. Readers should make inquiries specific to their practice environment and area to acquire comparative data for their personal use.

THIRD-PARTY PAYER PAYMENTS Some payers pay a percent of billed charges. Currently, however, third-party payers typically pay the hospital or surgicenter a flat fee from which all their expenses must be subtracted. Typically surgicenters are reimbursed at lower rates than hospitals. For outpatient ACLR in the Chicago area, these rates vary from a low of $1100 for Medicaid to between $1800 and $3000 for private payers and Medicare. Hospital admission for 1 night will typically actually decrease the reimbursement rate by causing the hospital to be paid its per-diem rate for 1 night instead of the outpatient surgery cost. For institutions performing high volumes of ACLR, “carve outs” become extremely important. These remove the ACLR from the fixed surgery reimbursement prepayment mode and substitute a percentage of charges or a higher reimbursement payment level. This is a matter of individual negotiation between the institution and the payer. Most payers also reimburse implant invoices, although some do not. These invoice reimbursements often will occur only above a certain threshold: for example, at the $1000 level. Risk contracts, in which institutions are paid globally for all care for a given number of lives, are still reasonably prevalent. They are of special concern to the institution when typical surgical costs are exceeded frequently.

INSTITUTIONAL FIXED COSTS These costs are a combination of time charges, which reflect fixed costs of operation such as rent, utilities, and staffing, and additional costs associated with the given procedure.1,2 In 1996, Novak et al2 published rates of $12,040 for hospital ACLR with admission, $8815 for hospital ACLR with same-day discharge, and $3853 for surgicenter ACLR. A representative survey of Chicago-area hospitals and surgicenters indicates that current total charges typically vary from $5000 to $12,000 for ACLR. In the following discussion, we will break down the component costs that are additive to the basic institutional time costs.

80

Anterior Cruciate Ligament Reconstruction–Specific Additive Costs Allografts Allografts are increasing rapidly in popularity. A survey of the largest U.S. tissue banks discloses a price range for various ACL allografts of $1400 to more than $3000, with a mean of about $2000 per case. A recently published study3 using patient data from 1996 to 1998 showed allografts at that time to substantially reduce costs by decreasing the likelihood of admission and decreasing surgical time. However, today virtually all ACLR procedures may be performed as outpatient with the use of femoral blocks (see later), so there is little further potential cost savings in this regard from the use of allografts. Even without the use of femoral blocks, ACLR can usually be performed easily on an outpatient basis. Allograft use will produce slightly decreased costs from reduced operating time due to the absence of a surgical harvest. Experienced surgeons will generally accomplish the harvest in about 10 minutes, but the time may be substantially higher for surgeons who perform the procedure only occasionally. In either case the reduced time will not significantly offset the high cost of the allograft; in addition, there is some diversion of assistant or surgeon time involved in opening, thawing, and washing the allograft. The other potential benefit of allograft use is avoidance of harvest morbidity. This may be significant regarding kneeling pain after bone–patellar tendon–bone (BPTB) harvest. The morbidity for hamstring harvest has been shown to be negligible. Disadvantages with allograft versus autograft use may include lower stability rates4 (see Chapter 69) as well as the small but definite risk of disease transmission. The cost implications of widespread allograft use are staggering. Macroeconomically, $2000 per allograft multiplied by an estimated 110,000 predicted ACLRs yields a cost differential of more than $200 million between no use of allografts and complete use of allografts nationwide. Microeconomically, if allografts are not separately reimbursed above the basic cost of the procedure, their use will virtually always cause the procedure to be performed at a net loss to the institution. Because most contracts do reimburse for allografts, this is often not an issue, but it is important to be aware of contract provisions at the given institution for the specific payer involved.

Fixation Implants We have surveyed the costs of the fixation implants produced by the major manufacturers of such devices. The cost range of these devices is summarized in Table 9-1. However, discounting of up to 25% below the listed range is common. Interference screws, which are still the most

The Economics of Anterior Cruciate Ligament Reconstruction TABLE 9-1 Economics of Anterior Cruciate Ligament Reconstruction Item

Cost Range ($)

Anterior Cruciate Ligament Instrumentation Tray Rental ACL tray rentals vary widely but will often cost the institution about $500.

ACLR implants Interference screws

9

200–300

Tibial fixation: other

80–500, typically 250

Femoral fixation: other

95–558, typically 250

Allograft cost

1400–3000, typically 2000

Total without allograft

500

Total with allograft

2500

Disposables Disposable pins and the like typically cost about $300 or less per case.

Total Cost

ACLR surgical costs Disposables

300

ACLR tray rentals

500

Total

800

Future costs Navigation

450

Double bundle

450 (extra fixation costs)

Tissue engineering

Unknown

Postoperative costs Continuous passive motion

>23/day

Cold machine

300

Postoperative brace

300

Functional brace Custom

1500

Shelf

800

Physical therapy

1000–3000

Femoral block

80

widely used devices, generally cost between $200 and $300 each. The cost differential between metal and bioabsorbable screws has largely disappeared, and most sales today are of the bioabsorbable devices. The former practice of using metal devices as a cost-saving measure is thus generally no longer productive. The tibial post screw stands alone as the least expensive tibial or femoral device, with a cost of less than $100. Some devices are priced as high as $500. In general there is little relationship between the sophistication of the device and its cost, and pricing by the companies would appear to be driven primarily by what the market will bear. Overall, combined tibial and femoral fixation device cost per case will generally be in the range of $400 to $500.

As is seen from the previous remarks and Table 9-1, disposables, tray rental, and fixation devices will produce an aggregate cost of $1200 per case; the cost is lower for the institution that owns its own ACL guide system. The addition of an allograft will increase the average cost to roughly $3200 per case. Thus, it can be seen that ACLR without allograft falls below total payer payments in virtually all cases, allowing the institution to retain some payment to cover its fixed costs. The addition of an allograft will not be problematic, provided it is separately reimbursed. Thus, from a microeconomic perspective, payer reimbursement of allografts becomes the key factor in preserving solvency.

Postoperative Costs Reimbursement is variable for some of the items in this section, as described here. If the surgeon wishes to use them, it is therefore important to check individual patient benefits to ensure that patients are not unexpectedly billed for items that they thought would be paid by their insurance provider.

Femoral Blocks In the Chicago area, femoral blocks are reimbursed at roughly $60 to $80 per block. They are reimbursed either using a specific Current Procedural Terminology (CPT) code or, more often, as an additional 15 minutes or so of anesthesia time. They have been shown to be highly cost effective by permitting reliable, same-day discharge.4–7 Although same-day discharge is routinely accomplished by most orthopaedic surgeons without the block, the block increases the percentage to nearly 100%, with greatly increased patient comfort. Pain is eliminated as a discharge obstacle, and nausea is also reduced as a discharge obstacle because there is no postoperative narcotic nausea exacerbation. Furthermore, femoral blocks clearly reduce short-term narcotic use after discharge, thus decreasing the incidence of nausea, constipation, and other opioid side effects at home, which can be significant in some patients. The small cost of the block is greatly outweighed by the overall reduced facility costs in allowing patients to leave the hospital expeditiously. The morbidity of these blocks has been negligible. 81

Anterior Cruciate Ligament Reconstruction

Cold Machines Motorized ice-flow machines cost about $300. They are beloved by patients for their pain-relieving properties. The literature, including a meta-analysis, shows their efficacy after ACLR8–10 and total knee arthroplasty.11 However, despite this favorable literature, third-party payers have increasingly refused to pay for motorized ice-flow machines in recent years. In the absence of insurance reimbursement, most patients are not willing to pay out of pocket for them.

Continuous Passive Motion Continuous passive motion (CPM) is somewhat less commonly used and more difficult to obtain reimbursement for than in prior years. Although early range of motion (ROM) may be improved, studies have failed to show significant benefit regarding ultimate ROM or postsurgical pain in ACLR.12–14 This parallels studies showing little or no long-term benefit after total knee arthroplasty.15–17 This literature has somewhat dampened third-party payer enthusiasm for these devices. The daily cost ranges upward from the Medicare rate of $23.

Postoperative Knee Braces Postoperative knee braces have a definite use in some rehabilitation protocols in regaining knee extension. They also provide protection in the postoperative period. Some surgeons do not use them. They are universally paid by payers as a separate cost item.

Functional Knee Braces So-called derotation braces were formerly routinely used when patients returned to pivoting activities. However, today they are used by far fewer surgeons than in past years. In the presence of a stable knee, there is no evidence that they are of significant benefit. In addition, the costs can be substantial, especially for custom braces. Many payers will reimburse the approximate $800 cost of “off the shelf” braces but not the higher $1500 price tag of custom braces.

but some do not. The number of available visits should be known in advance so that the surgeon does not use them all before the rehabilitation is completed. Many, but not all, plans will allow expanded benefits in cases of special need after appropriate appeal.

Future Added Costs Navigation Computerized navigation systems have been introduced18,19 but are not currently in widespread use. Their advantage is said to be greater tunnel placement accuracy. It is not clear whether their use will ever be widespread, but if so, they will add both direct cost and increased operative time cost to ACLR. The current cost of bringing in a system for a case is about $450. There is insufficient literature to evaluate relative outcomes with and without navigation. Some believe that the less-expensive option of simple intraoperative radiographs without computerized navigation can also be efficacious.

Double-Bundle Anterior Cruciate Ligament Reconstruction Double-bundle ACLR is more time consuming than singlebundle cases and thus increases surgical times. It also generally doubles implant costs because two femoral and two tibial implants are needed in most cases—an approximate average increase of $450 per case for fixation implants alone. Early clinical results have been good,20,21 but it is too soon to know whether the benefits are sufficient to justify the increased time, difficulty, and cost. Because many plans do not reimburse invoices at such a low level, the extra implant costs may ultimately be subtracted from the often-thin profit margin of these cases.

Tissue Engineering The use of growth factors and delivery vehicles for them is imminent.22,23 This will inevitably add significant cost to ACLR.

Physical Therapy Adequate physical therapy is necessary to restore motion, strength, and function. Although the costs vary by orders of magnitude among various regimens, there is little evidence regarding relative efficacies. Primarily home-based regimens are clearly more economical, but it is not clear that they are equally effective with clinic-based regimens. Also, the quantity of therapy needed varies somewhat by the demands of the patient, with high-performance competitive athletes generally needing more than others. Individual visit charges are also quite variable. The approximate cost range can vary from about $1000 to $3000 and much more in some cases. Most plans include physical therapy benefits, 82

CONCLUSIONS 1 Allograft usage is currently the largest and most important cost factor in ACLR. Macroeconomically, allograft use can potentially add almost $200 million to U.S. annual ACLR expenditures. Microeconomically, it is imperative that contracting provides for separate reimbursement above the basic cost of the procedure to avoid net loss to the institution. 2 Femoral nerve blocks are a cost-effective means to avoid the adverse economic effects of patient admission and improve postoperative pain control.

The Economics of Anterior Cruciate Ligament Reconstruction 3 CPM machines, cold machines, and functional knee braces are no longer universally reimbursed. Physical therapy is almost always covered but at variable levels. Patient benefits should be determined prior to prescription. 4 Tissue engineering, navigation, and double-bundle techniques will increase ACLR cost if they come into widespread use. Outcome studies will be necessary to determine whether benefits justify costs. 5 Surgeon choice is the most important factor in determining macroeconomic societal expense and microeconomic institutional solvency for ACLR. It is important to weigh patient outcomes against costs.

References 1. Curran AC, Park AE, Bach BR Jr, et al. Outpatient anterior cruciate ligament reconstruction: an analysis of changes and perioperative complications. Am J Knee Surg 2001;14:145–151. 2. Novak PJ, Bach BR Jr, Bush-Joseph CA, et al. Cost containment: a change comparison of anterior cruciate ligament reconstruction. Arthroscopy 1996;12:160–164. 3. Cole DW, Ginn TA, Chen GJ, et al. Cost comparison of anterior cruciate ligament reconstruction: autograft versus allograft. Arthroscopy 2005;21:786–790. 4. Dauri M, Polzoni M, Fabbi E, et al. Comparison of epidural continuous femoral block and intraarticular analgesia after anterior cruciate ligament reconstruction. Acta Anaesthesiol Scand 2003;47:20–25. 5. Williams BA, Kentor ML, Vogt MT, et al. Economics of nerve block pain management after anterior cruciate ligament reconstruction: potential hospital cost savings via associated postanesthesia care unit bypass and same-day discharge. Anesthesiology 2004;100:697–706. 6. Edkin BS, Spindler KP, Flanagan JF. Femoral nerve block as an alternative to parenteral narcotics for pain control after anterior cruciate ligament reconstruction. Arthroscopy 1995;11:404–409. 7. Williams BA, DeRiso BM, Figallo CM, et al. Benchmarking the perioperative process: III. Effects of regional anesthesia clinical pathway techniques on process efficiency and recovery profiles in ambulatory orthopedic surgery. J Clin Anesth 1998;10:570–578. 8. Raynor MC, Pietrobon R, Guiller U, et al. Cryotherapy after ACL reconstruction: a meta analysis. J Knee Surg 2005;18:123–129.

9

9. Barber FA. A comparison of crushed ice and continuous flow cold therapy. Am J Knee Surg 2000;13:97–101. 10. Barber FA, McGuire DA, Click S. Continuous-flow cold therapy for outpatient anterior cruciate ligament reconstruction. Arthroscopy 1998;14:130–135. 11. Morsi E. Continuous-flow cold therapy after total knee arthroplasty. J Arthroscopy 2002;17:718–722. 12. Gaspar L, Farkas C, Szepesi K, et al. Therapeutic value of continuous passive motion after anterior cruciate replacement. Acta Chir Hung 1997;36:104–105. 13. McCarthy MR, Yates CK, Anderson MA, et al. The effects of immediate continuous passive motion on pain during the inflammatory phase of soft tissue healing following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther 1993;17:96–101. 14. Richmond JC, Gladstone J, MacGillivray J. Continuous passive motion after arthroscopy assisted anterior cruciate ligament reconstruction: comparison of short- versus long-term use. Arthroscopy 1991;7:39–44. 15. Leach W, Reid J, Murphy F. Continuous passive motion following total knee replacement: a prospective randomized trial with follow-up to 1 year. Knee Surg Sports Traumatol Arthrosc 2006;14:922–926. 16. Denis M, Moffet H, Caron F, et al. Effectiveness of continuous passive motion and conventional phsycial therapy after total knee arthroplasty: a randomized clinical trial. Phys Ther 2006;86:174–185. 17. Lau SK, Chin KY. Use of continuous passive motion after total knee arthroplasty. J Arthroplasty 2001;16:336–339. 18. Plaweski S, Cazal J, Rosell P, et al. Anterior cruciate ligament reconstruction using navigation: a comparative study on 60 patients. Am J Sports Med 2006;34:542–552. 19. Hiraoka H, Kuribayashi S, Fukuda A, et al. Endoscopic anterior cruciate ligament reconstruction using a computer-assisted fluoroscopic navigation system. J Orthop Sci 2006;11:159–166. 20. Muneta T, Koga H, Morito T. A retrospective study of the midterm outcome of two-bundle anterior cruciate ligament reconstruction using quadrupled semitendinosus tendon in comparison with one-bundle reconstruction. Arthroscopy 2006;22:252–258. 21. Yasuda K, Kondo E, Ichiyama H, et al. Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction procedure using hamstring tendon grafts: comparisons among three different procedures. Arthroscopy 2006;22:240–251. 22. Ju YJ, Tohyama H, Kondo E, et al. Effects of local administration of vascular endothelial growth factor on properties of the in situ frozen-thawed anterior cruciate ligament in rabbits. Am J Sports Med 2006;34:84–91. 23. Yamazaki S, Yasuda K, Tomita F, et al. The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of the anterior cruciate ligament in dogs. Arthroscopy 2005;21:1034–1041.

83

10 CHAPTER

Chadwick C. Prodromos Brian T. Joyce

PART A GRAFT MECHANICAL PROPERTIES

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts INTRODUCTION Graft strength is only one of the factors influencing anterior cruciate ligament (ACL) graft choice. However, it has a direct bearing on ultimate stability, which is the goal of ACL. The relative strengths of potential ACL grafts are often not clearly appreciated. It is the purpose of this chapter to present the available data on the relative strengths of tendons that can be used as ACL reconstructive grafts.

METHODS Table 10–1 summarizes the data that we were able to find in the literature on graft strengths. Load to failure (LTF) is the parameter compared in each case. This data was found from computerized literature searches targeting ACL reconstruction and each of the specific grafts in clinical use. Although some tissue banks have performed their own studies on graft strengths, we have purposely excluded such proprietary data and relied only on data published in the peer-reviewed literature to avoid bias.

COMPARISON OF GRAFT STRENGTHS There is significant variability in LTF results among different studies for the same graft (see Table 10–1). This is likely related to differences in testing methodologies. Thus, it is necessary to look at the totality of the data to get an overall idea of relative graft strengths. Some of the 84

authors have what appears to be outlier LTFs, but the relative strengths between grafts within their study generally reflect the bulk of the literature. The two main examples here are the data of Brahmabhatt21 and Harris, with low LTFs for all grafts tested relative to other studies. When comparing grafts it is important also to notice the configuration of the tested grafts; in other words, whether it is a single, double, or quadruple graft, and in the case of bone–patellar tendon–bone (BPTB), whether it is a 10-mm or 15-mm graft. The data in Table 10–1 also show that braiding of grafts has been shown to weaken rather than strengthen grafts and is not clinically indicated.

EFFECT OF LIGAMENTIZATION Chapter 55 describes the effects of ligamentization on graft strength. Although there is some disagreement, it appears that grafts retain only about half their initial strength at long-term follow-up. Thus, grafts that are significantly stronger than the native ACL at time zero may indeed be necessary to produce ultimate strengths that are as strong as the ACL initially was. Indeed, some studies report a lower re-rupture rate for reconstructed ACLs than for the contralateral normal ACL,1 perhaps due to greater graft strength.

ALLOGRAFT STRENGTHS Autograft strengths are relatively straightforward to measure. However, allograft strengths

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts

10

TABLE 10–1 Load to Failure Data for Anterior Cruciate Ligament Grafts Author

Year

Graft

Average

SD

Author

Year

Graft

Average

Load to

Load to

Failure (N)

Failure (N)

Allografts

SD

Hamner22

1999

2ST/2Gr

3880.0

NR

Haut22

2002

Double anterior tibialis

4122.0

893.0

Noyes19

1984

2ST/2Gr

4108.0

NR

Pearsall27

2003

Double anterior tibialis

3412.0

NR

Hamner22

1999

2ST/2Gr

4090.0

295.0

24

2003

2ST/2Gr

3000.0

563.0

2003

2ST/2Gr

3404.2

922.0

2002

2ST/2Gr

2913.0

645.0

2003

2ST/2Gr—braided

1673.0

504.0

2003

2ST/2Gr—braided

2223.5

1056.0

Pearsall

27

Haut22 Pearsall

27

King30 King

30

2003

Double peroneus

2483.0

NR

Kim

2002

Double post tibialis

3594.0

1330.0

Millett23 22

2003

Double post tibialis

3391.0

NR

Haut

2004

Achilles

1470.0

511.9

Kim24

2004

Tibialis

1806.7

496.2

25

Millett

Bone–patellar tendon–bone (BPTB)

Semitendinosus (ST) Brahmabhatt21

1999

Double ST

1029.0

158.4

Noyes19

1984

15-mm BPTB

2734.0

298.0

Hamner22

1999

Double ST

2330.0

452.0

Noyes19

1984

15-mm BPTB

2900.0

260.0

King30

2004

Double ST

1640.7

236.5

Harris31

1997

10-mm BPTB

876.0

NR

Noyes19

1984

Single ST

1216.0

50.0

Brahmabhatt21

1999

10-mm BPTB

850.0

159.2

Hamner22

1999

Single ST

1060.0

227.0

King30

Gracilis (Gr)

2004

10-mm BPTB

863.9

417.4

19

1984

10-mm BPTB

1822.7

NR

Noyes19

Noyes

Brahmabhatt21 22

1999

Double Gr

648.7

112.4

1984

10-mm BPTB

1933.3

NR

20

Hamner

1999

Double Gr

1550.0

428.0

Cooper

1993

10-mm BPTB

2664.0

395.0

Noyes19

1984

Single Gr

838.0

30.0

Cooper20

1993

10-mm BPTB

3057.0

351.0

1999

Single Gr

837.0

138.0

Quadriceps 1999

Quadriceps/bone

991.0

282.0

1997

Quadriceps/bone

1075.0

NR

22

Hamner

Double ST/double Gr (2ST/2Gr) 21

Brahmabhatt

1999

2ST/2Gr

Brahmabhatt21 1677.0

NR

Harris

31

NR, Not reported.

are more complicated because of the varying effects of graft preparation and sterilization techniques on the graft. Thus, any study that measures allograft strength can only be considered accurate for an allograft prepared in a similar manner. The relevant parameters may include radiated versus not radiated, the amount of radiation, and whether or not a radioprotectant was used. Other processes shown to significantly affect tissue properties include the use of cryoprotectant2 and even simple freezing.3 This is further complicated by the fact that these parameters may affect allograft strength at longer-term follow-up by influencing revascularization and cellular repopulation in addition to their effects at time zero. Thus, time zero data may not be sufficient for comparison between autografts and allografts, particularly in light of evidence that late failure rates may

be higher for allografts than for autografts.4–7 The literature has also shown overall lower stability rates for allograft BPTB versus autograft BPTB,8–17 suggesting that ligamentization may weaken allografts more than autografts.18

QUADRICEPS TENDON GRAFT STRENGTH The only published data we could find was from Brahmabhatt and Harris. Their LTF for the quadriceps tendon (QT) graft is quite low. However, we believe the proper way to interpret these data is by comparing them with their BPTB data, which are also much lower than other studies, probably due to testing methodology. The important point is that the QT LTF values in both of these studies are each about 20% 85

Anterior Cruciate Ligament Reconstruction stronger than the LTF for 10-mm BPTB tested the same way. Therefore, it would appear that a QT graft is likely a little stronger than a 10-mm BPTB graft.

RELATIVE STRENGTH OF HAMSTRING AND BONE–PATELLAR TENDON–BONE GRAFTS The classic paper of Noyes et al19 first compared various tissues with the ACL from the same cadaveric specimen. Other works have followed a similar methodology. These studies are summarized in Table 10–1. It should be noted that the study by Noyes et al used a 15-mm BPTB graft, whereas in practice a roughly 10-mm graft is used. Extrapolating from their numbers, a 10-mm BPTB graft would be 110% as strong as the native ACL. A two-strand semitendinosus (ST) and two-strand gracilis (Gr) (2ST/2Gr) graft would be 238% as strong as the native ACL. A four-strand ST (4ST) would be 280% as strong as the ACL. The real values for these multistrand grafts are probably a little less than these extrapolations because it is unlikely that the entire tendon is as strong as these index values. Some more recent studies have produced very different absolute numbers, perhaps related to testing methodological differences.20–29 However, within studies the relative strengths of various grafts show general agreement.

OVERALL RELATIVE GRAFT STRENGTHS Overall, 4ST and 2ST/2Gr grafts would appear to be the strongest available grafts in common use. Two-strand tibialis grafts are nearly as strong, followed by 10-mm BPTB and peroneus grafts, which are roughly two-thirds as strong as four-strand hamstring grafts. It should be pointed out that 15-mm BPTB can be used as an allograft and will more closely approximate the strength of a four-strand hamstring graft. The only data of which we are aware on tendo Achilles grafts show a low LTF. From the high girth of the graft it is likely, however, that a full-thickness tendo Achilles graft has much greater strength. This supposition will require more testing for validation.

CONCLUSIONS 1 Four-strand hamstring autografts are the strongest available grafts, followed by tibialis, QT, and BPTB grafts, with insufficient data to evaluate tendo Achilles grafts. All have greater strength than the native ACL. 2 Graft strength is only one of many factors contributing to knee stability after ACL reconstruction. 86

3 Because grafts appear to retain only about half of their time zero strength at ultimate follow-up, grafts significantly stronger than the native ACL would seem to be desirable. 4 Allograft ligamentization has not been well studied. LTF studies between autografts and allografts may not be comparable if the ligamentization of allografts differs significantly from that of autografts.

References 1. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 2. Caborn D, Nyland J, Chang HC, et al. Tendon allograft cryoprotectant incubation and rehydration time alters mechanical stiffness properties. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May 2006. 3. Clavert P, Kempf JF, Bonnomet F, et al. Effects of freezing/thawing on the biomechanical properties of human tendons. Surg Radiol Anat 2001;23:259–262. 4. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at the 2006 Symposium of the American Academy of Orthopaedic Surgeons. AAOS Symposium; Controversies in Soft Tissue ACL Reconstruction, Chicago, May, 2006. 5. Scheffler S, Unterhauser F, Keil J, et al. Comparison of tendon-to-bone healing after soft tissue autograft and allograft ACL reconstruction in a sheep model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 6. Siegel MG. Personal communication. Meeting of the Arthroscopy Association of North America, Hollywood, Florida, May, 2006. 7. Risinger RJ, Bach BR, Jr. Late anterior cruciate ligament reconstruction failure by femoral bone plug dislodgement. J Knee Surg 2006;19:202–205. 8. Barrett G, Stokes D, White M. Anterior cruciate ligament reconstruction in patients older than 40 years: allograft versus autograft patellar tendon. Am J Sports Med 2005;33:1505–1512. 9. Gorschewsky O, Klakow A, Riechert K, et al. Clinical comparison of the Tutoplast allograft and autologous patellar tendon (bone–patellar tendon–bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. Am J Sports Med 2005;33:1202–1209. 10. Harner CD, Olson E, Irrgang JJ, et al. Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop Rel Rsch 1996;324:134–144. 11. Kleipool AEB, Zijl JAC, Willems WJ. Arthroscopic anterior cruciate ligament reconstruction with bone-patellar tendon-bone allograft or autograft: a prospective study with an average follow up of 4 years. Knee Surg Sports Traumatol Arthrosc 1998;6:224–230. 12. Peterson RK, Shelton WR, Bomboy AL. Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy 2001;17:9–13. 13. Shelton WR, Papendick L, Dukes AD. Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy 1997;13:446–449. 14. Stringham DR, Pelmas CJ, Burks RT, et al. Comparison of anterior cruciate ligament reconstruction using patellar tendon autograft or allograft. Arthroscopy 1996;12:414–421. 15. Victor J, Bellemans J, Witvrouw E, et al. Graft selection in anterior cruciate ligament reconstruction—prospective analysis of patellar tendon autografts compared with allografts. Int Orthop 1997;21:93–97. 16. Zijl JAC, Kleipool AEB, Willems WJ. Comparison of tibial tunnel enlargement after anterior cruciate ligament reconstruction using patellar tendon autograft or allograft. Am J Sports Med 2000;28:547–551.

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts 17. Chang SKY, Egami DK, Shaib MD, et al. Anterior cruciate ligament reconstruction: allograft versus autograft. Arthroscopy 2003;19:453–462. 18. Prodromos CC, Joyce BT, Shi KS. A meta-analysis of stability of autografts compared to allografts after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc (In press). 19. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg Am 1984;66A:344–352. 20. Brahmabhatt V, Smolinski R, McGlowan J, et al. Double-stranded hamstring tendons for anterior cruciate ligament reconstruction. Am J Knee Surg 1999;12:141–145. 21. Cooper DE, Deng XH, Burstein AL, et al. The strength of the central third patellar tendon graft. Am J Sports Med 1993;21:818–824. 22. Haut Donahue TL, Howell SM, Hull ML, et al. A biomechanical evaluation of anterior and posterior tibialis tendons as suitable single-loop anterior cruciate ligament grafts. Arthroscopy 2002;18:589–597. 23. Hamner DL, Brown CH Jr, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81A:549–557. 24. Kim DH, Wilson DR, Hecker AT, et al. Twisting and braiding reduces the tensile strength and stiffness of human hamstring tendon

25.

26. 27.

28.

29.

30.

31.

10

grafts used for anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:861–867. Millett PJ, Miller BS, Close M, et al. Effects of braiding on tensile properties of four-strand human hamstring tendon grafts. Am J Sports Med 2003;31:714–717. Nicklin S, Waller C, Walker P, et al. In vitro structural properties of braided tendon grafts. Am J Sports Med 2000;28:790–793. Pearsall AW, Hollis JM, Russel GV, et al. A biomechanical comparison of three lower extremity tendons for ligamentous reconstruction about the knee. Arthroscopy 2003;19:1091–1096. Stapleton TR, Curd DT, Baker CL Jr. Initial biomechanical properties of anterior cruciate ligament reconstruction autografts. J South Orthop Assoc 1999;8:173–180. Tis JE, Klemme WR, Kirk KL, et al. Braided hamstring tendons for reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:684–688. King W, Mangan D, Endean T, et al. Microbial sterilization and viral inactivation in soft tissue allografts using novel applications of high-dose gamma irradiation. Presented at the American Academy of Orthopaedic Surgeons, March 2004, San Francisco,CA. Harris NL, Smith DA, Lamoreaux L, Purnell M. Central quadriceps tendon for anterior cruciate ligament reconstruction. Part I: Morphometric and biomechanical evaluation. Am J Sports Med 1997;5:725–727.

87

11 CHAPTER

Don Johnson

Why Synthetic Grafts Failed HISTORY OF SYNTHETIC GRAFTS FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Synthetic grafts for anterior cruciate ligament (ACL) reconstruction had a brief period of popularity in the mid-1980s. At this time the routine operation was an open patellar tendon graft with 6 weeks of postoperative immobilization. The concept of implanting a sterile, off-the-shelf synthetic ligament with no postoperative immobilization was very appealing. There was no harvest site morbidity, and the rehabilitation was very quick. In a very short period, it was recognized that there was a higher rate of failure compared with autogenous grafts, an increased rate of late infection, considerable bone tunnel enlargement, and significant sterile effusions; in addition, the grafts were expensive. In a 2005 article reviewing the choices of graft for ACL reconstruction, West and Harner1 stated that there is no indication for synthetic ligaments.

TYPES OF SYNTHETIC GRAFTS During the 1980s, numerous synthetic grafts were developed. They were used either as augmentation or as a complete prosthetic replacement. One of the original grafts that was designed as an augmentation device was the Kennedy ligament augmentation device (LAD). When this graft was sutured to the autogenous graft and fixed to the bone at both ends, it 88

stressed shielded the autogenous graft and led to failure. Gore-Tex was a prosthetic graft, but it was placed in a nonanatomical position over the top of the femur. The theory was to avoid the bending forces at the entrance to a femoral tunnel. However, because this was a nonanatomical position, it eventually led to graft failure at the proximal tunnel (a second tunnel was drilled in the femur several inches above the joint capsule). The Styker Dacron graft was a complete replacement graft placed through anatomical tunnels in the femur and tibia. The ABC graft was a combination of polyester and carbon fiber, and it was also placed through bony tunnels. The Ligastic graft was another polyester graft that evolved to the LARS graft. This was placed through bony tunnels and could be used as augmentation or as a complete prosthetic replacement. The graft was anchored in the tunnels with metal interference screws. The Leeds-Keio was a coventure between Leeds University in England and Keio University in Japan. This was a polyester mesh graft designed to augment the autogenous graft. It was placed through bony tunnels and anchored outside the tunnel with staples. The Trevira ligament was polyester and resembled the LAD in design, but it was placed in a nonanatomical position.

CAUSES OF FAILURE OF SYNTHETIC GRAFTS The most common cause of failure of synthetic grafts was the fiber abrasion due to bending forces

Why Synthetic Grafts Failed over the edge of the bony tunnels (Fig. 11-1). In order to avoid this problem, the Gore-Tex graft was placed over the top of the femur. This nonanatomical position eventually led to graft failure. Carson et al2 have stated that approximately 50% of the failures of ACL reconstruction are due to technical error, and the anterior femoral tunnel placement is one of the most common errors. It is likely that many of the failures of synthetic grafts were due to the same causes. The literature has numerous articles reporting the unacceptable failure rate after synthetic ACL reconstruction. Kumar and Maffuli3 reported on the stress shielding caused by the use of the LAD. Riel4 reported numerous complications following the use of the LAD and concluded that there was no indication for its use. Muren et al5 published results that showed no advantage to augmenting the patellar tendon graft with the LAD device. Guidoin et al6 reviewed 69 failed synthetic fiber ligament grafts and found that they all failed by fiber abrasion of the textile fiber around the bony tunnel edge. Kock et al7 stated that the Trevira ligament failed due to fiber abrasion and the nonanatomical position of the graft. Wredmark and Engstrom8 reviewed the results of the Stryker Dacron graft and found an 80% failure rate. Engstrom et al9 also compared the Leeds-Keio with an autogenous patellar tendon graft and found the failure rate of the synthetic to be unacceptable. Andersen et al10 reported unsatisfactory results with the Dacron synthetic graft. Bowyer and Matthews11 reported an unacceptable failure rate with the Gore-Tex ligament graft. Indelicato et al12 reported on the sterile effusions that were foreign body reactions to the synthetic graft. Woods et al13 published the deteriorating results of the Gore-Tex graft with longer follow-up from 2 to 3 years. Barrett et al14 also reported on the high failure rate (47%) with the Dacron synthetic ligament. This ligament had been placed in a nonanatomical, over-the-top position. Paulos et al15 reported 13% fair and 42% poor results with the Gore-Tex graft. Looseness and failure of the graft occurred in 30% of the cases with this graft placed in the over-the-top position. The 2.7% infection rate was higher than that reported with autogenous grafts.

FIG. 11-1 The Gore-Tex ligament failure at the tunnel entrance.

11

OTHER PROBLEMS WITH SYNTHETIC GRAFTS The problem of synthetic grafts is not only that they failed, but that there were other significant issues such as biocompatibility. The carbon fiber grafts produced a black synovitis in the joint. The regional lymph nodes also became enlarged with the carbon fiber debris. The Gore-Tex ligament often produced a very severe sterile synovitis that resembled a septic arthritis (Fig. 11-2). This prompted many patients to undergo a repeat arthroscopy to irrigate the joint. Biopsy of the synovium showed a foreign body reaction. The Gore-Tex ligament would occasionally produce a ganglion-type reaction at the tibial tunnel that required excision (Fig. 11-3). The bony tunnels would often become extremely large, requiring removal of the graft and bony grafting of the tunnels (Fig. 11-4). The revision ACL reconstruction would be staged some months later, when the bony tunnels had healed.

THE FUTURE There is still considerable interest and investigation into some form of synthetic bioabsorbable scaffold to implant into the stump of the ACL after injury to the ligament.16 In fact, a type of scaffold that is augmented with growth factors holds the most promise for the future. This minimally invasive approach to ACL repair would be an improvement over the relatively barbaric procedure of harvesting of the hamstring tendons to reconstruct the ACL.

FIG. 11-2 The severe foreign body reaction to the Gore-Tex ligament.

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Anterior Cruciate Ligament Reconstruction

FIG. 11-3 A large ganglion type of foreign body reaction at the tibial tunnel entrance.

References 1. West RV, Harner CD. Graft selection in anterior cruciate ligament reconstruction. J Am Acad Orthop Surg 2005;13:197–207. 2. Carson EW, Anisko EM, Restrepo C, et al. Revision anterior cruciate ligament reconstruction: etiology of failures and clinical results. J Knee Surg 2004;17:127–132. 3. Kumar K, Maffullli N. The ligament augmentation device: an historical perspective. Arthroscopy 1999;15:422–432. 4. Riel KA. [Augmented anterior cruciate ligament replacement with the Kennedy-LAD (ligament augmentation device)—long term outcome]. Zentralbl Chir 1998;123:1014–1018. 5. Muren O, Dahlstedt L, Dalen N. Reconstruction of acute anterior cruciate ligament injuries: a prospective, randomised study of 40 patients with 7-year follow-up. No advantage of synthetic augmentation compared to a traditional patellar tendon graft. Arch Orthop Trauma Surg 2003;123:144–147. 6. Guidoin MF, Marois Y, Bejui J, et al. Analysis of retrieved polymer fiber based replacements for the ACL. Biomaterials 2000;21:2461–2474. 7. Kock HJ, Sturmer KM, Letsch R, et al. Interface and biocompatibility of polyethylene terephthalate knee ligament prostheses. A histological and ultrastructural device retrieval analysis in failed synthetic implants used for surgical repair of anterior cruciate ligaments. Arch Orthop Trauma Surg 1994;114:1–7. 8. Wredmark T, Engstrom B. Five-year results of anterior cruciate ligament reconstruction with the Stryker Dacron high-strength ligament. Knee Surg Sports Traumatol Arthrosc 1993;1:71–75. 9. Engstrom B, Wredmark T, Westblad P. Patellar tendon or Leeds-Keio graft in the surgical treatment of anterior cruciate ligament ruptures. Intermediate results. Clin Orthop Relat Res 1993;6:190–197.

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FIG. 11-4 The tunnel enlargement (arrows) after a Gore-Tex ligament implantation.

10. Andersen HN, Bruun C, Sondergard-Petersen PE. Reconstruction of chronic insufficient anterior cruciate ligament in the knee using a synthetic Dacron prosthesis. A prospective study of 57 cases. Am J Sports Med 1992;20:20–23. 11. Bowyer GW, Matthews SJ. Anterior cruciate ligament reconstruction using the Gore-Tex ligament. J R Army Med Corps 1991;137:69–75. 12. Indelicato PA, Pascale MS, Huegel MO. Early experience with the GORE-TEX polytetrafluoroethylene anterior cruciate ligament prosthesis. Am J Sports Med 1989;17:55–62. 13. Woods GA, Indelicato PA, Prevot TJ. The Gore-Tex anterior cruciate ligament prosthesis. Two versus three year results. Am J Sports Med 1991;19:48–55. 14. Barrett GR, Line LL Jr, Shelton WR, et al. The Dacron ligament prosthesis in anterior cruciate ligament reconstruction. A four-year review. Am J Sports Med 1993;21:367–373. 15. Paulos LE, Rosenberg TD, Grewe SR, et al. The GORE-TEX anterior cruciate ligament prosthesis. A long-term followup. Am J Sports Med 1992;20:246–252. 16. Bourke SL, Kohn J, Dunn MG. Preliminary development of a novel resorbable synthetic polymer fiber scaffold for anterior cruciate ligament reconstruction. Tissue Eng 2004;10:43–52.

PART B AUTOGRAFT HARVEST TECHNIQUES

Hamstring Harvest Technique for Anterior Cruciate Ligament Reconstruction ABSTRACT The use of the hamstring tendons for anterior cruciate ligament (ACL) reconstruction has gained in popularity over the past several years. For those unfamiliar with the harvest technique of the hamstring tendons, this is often the most difficult part of the procedure. Several important steps in the procedure are described to avoid the common complication of cutting the grafts short.

TECHNIQUE OF HAMSTRING GRAFT HARVEST The graft harvest can be the most difficult aspect of this operation. Videotapes of this technique by Fowler, Prodromos, and Fox are available from the AAOS library.1 The anatomy of the hamstrings has been described in the literature by Ferrari and Ferrari.2 The strength of the hamstrings after harvest of the tendons was initially reported by Lipscomb et al3 to be the same as the opposite side. Since then, weakness of knee flexion above 90 degrees of knee flexion has been reported.4 Based on these reports, one should be cautious in recom­ mending hamstring grafts for sprinters, who require full, active knee flexion strength. Yasuda et al5 have described the harvest site morbidity as minimal. Gobbi et al6 recommend preser­ vation of the gracilis to prevent postoperative knee flexion weakness. The regeneration of the

hamstring tendons after the harvest was described by Cross et al.7

12 CHAPTER

Don Johnson

SKIN INCISION The skin incision for hamstring harvest should be made with the knee flexed in the figure-four position (Fig. 12-1). An oblique, 3-cm skin incision is made 5 cm below the joint line over the proximal edge of the pes anserine. The inci­ sion should start 1 cm medial to the tibial tuber­ cle and then continue posteromedially. The oblique incision is preferable to the vertical inci­ sion for two reasons: It gives a greater exposure to the top of the pes anserine, and it also has less potential to injure the infrapatellar branch of the saphenous nerve. Plan to harvest the graft and drill the tibial tunnel through this incision. Incise the subcutaneous fat, and strip the fat off the pes anserine with a sponge.

EXPOSURE OF THE TENDON Identify the superior border of the pes by pal­ pating the superior edge with your finger. Lift up this superior border, and incise the fascia. Identify the bursa between the pes and the medial collateral ligament by placing the tip of the scissors in the space. With the scissors, continue the incision medially down the tibia, in an L-shaped fashion, removing the tendons distally. Use a Kocher to apply traction to this

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Anterior Cruciate Ligament Reconstruction

TENDON RELEASE Free the distal end of the tendon with the scissors. Make sure you get the full length distally. Grasp it with a Kocher, and pull it firmly into the incision. Many of the bands can be released with the traction and by blunt finger dissection. The main band that goes to the medial head of the gastrocne­ mius will usually have to be cut with the scissors (Fig. 12-3). Pull firmly on the tendon, and cut away from the tendon (to avoid cutting the tendon with the scissors) (Fig. 12-4). The tendon should not retract proximally if all the bands are cut. When the tendon is pulled distally, there is no dimpling posteriorly over the gastrocnemius.

STRIPPING OF THE TENDON FIG.12-1 The oblique anteromedial incision for hamstring harvest.

Advance the tendon stripper up over the tendon to free it from the muscle proximally (Fig. 12-5). The key to a successful

top corner. Turn the pes down to look on the underside for the most inferior tendon, the semitendinosus (Fig. 12-2). Lift the tendon up with the tip of the scissors, and grasp it with a Kocher. Lift up the gracilis, and grasp it in a similar fashion with a Kocher. Divide the conjoined tendon between the semitendinosus and the gracilis.

FIG. 12-3 The bands from the tendon to the gastrocnemius are identified and cut.

FIG. 12-2 The pes is turned down to visualize the tendons on the underside.

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FIG. 12-4 The scissors are used to cut the bands to the gastrocnemius.

Hamstring Harvest Technique for Anterior Cruciate Ligament Reconstruction

12

FIG. 12-7 The two tendons are looped over a suture. FIG. 12-5 The tendon stripper is pushed up the tendon to remove it proximally from the muscle.

harvest is to keep tension on the distal end. This will prevent the tendon from folding over and being cut off short (Fig. 12-6). Make sure that the tendon stripper is heading up the thigh in the same direction as the tendon. There is often resistance at the muscle tendon junction, and the stripper should be rotated to slip it up along the surface of the muscle. This gives extra length. The total length is usually 28 to 30 cm. Strip the gracilis tendon in a similar fashion.

PREPARATION OF THE GRAFT Preparation of the Four-Bundle Semitendinosus and Gracilis Graft Take the graft to the graft master on the back table. Lay out, measure, and cut the graft to 22 cm. Remove the muscle with the periosteal elevator. Loop the two tendons over a

FIG. 12-6 One small band may kink the tendon, and the stripper will cut the tendon off short.

#5 braided nonabsorbable suture to produce an 11-cm graft (Fig. 12-7). With this length, 2.5 cm is in the femur, 2.5 cm is intraarticular, and 5 cm is in the tibial tunnel. This ensures a small portion of the graft is at the cortex of the tibia for fixation with the screw. Whipstitch the individual ends of the tendons with a #2 nonabsorbable suture for a distance of 4 cm (Fig. 12-8). Make sure that each tendon has a suture in it. This allows you to tension each bundle of the composite graft. The completed four-bundle graft should be 11 cm in length. This four-bundle graft will be three times the strength of a single strand of semitendi­ nosus, assuming all bundles are equally tensioned.8 Incor­ porate the graft into the bone tunnel by Sharpey fibers.9 This will take about 10 to 12 weeks to heal. This graft will have at least 2.5 cm of graft in each tunnel. The depth of graft in the tunnel can be determined by the suture marks at each end.

Graft Sizing Measure the size of the composite graft to the nearest half centimeter (7.5 mm and 8 mm are the most common sizes) (Fig. 12-9). Drill the tunnels according to the size of the tendon.

FIG. 12-8 The tendon ends are whipstitched individually.

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Anterior Cruciate Ligament Reconstruction the tendons into the wound to avoid pushing the scissors proximally and injuring the saphenous nerve.

� After the bands have been divided and there is no dimpling of the skin when the tendon is tugged, you can proceed to use the stripper to remove 22 to 25 cm of tendon. FIG. 12-9 Sizing of the graft.

TIPS FOR HARVESTING THE HAMSTRING GRAFTS TO AVOID COMPLICATIONS � Make sure that the incision is in the correct position to easily access the tendons. The landmarks are found with the knee in the figure-four position. The incision should be oblique, running from 2 cm medial to the tibial tubercle and 5 cm below the joint line (3 fingerbreadths) and directly along the course of the tendons.

� After making the skin incision and stripping the fat off the fascia, palpate the tendons and incise the fascia on the superior surface.

� Use the tip of the Metz to fall into the pes bursa. This ensures that you are in the correct plane and will not dissect under the medial collateral ligament.

� Use the scissors or knife to remove the tendon attachment to the tibia. Turn this flap over to visualize the two tendons. Split the conjoined tendon distally.

� Now pull the tendon into the wound to show the bands that attach to the gastrocnemius. It is preferable to pull

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References 1. www.aaos.org. 2. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev 1991;20:1085–1088. 3. Lipscomb AB, Johnston RK, Snyder RB, et al. Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament. Am J Sports Med 1982;10:340–342. 4. Tashiro T, Kurosawa H, Kawakami A, et al. Influence of medial hamstring tendon harvest on knee flexor strength after anterior cruciate ligament reconstruction. A detailed evaluation with comparison of single- and double-tendon harvest. Am J Sports Med 2003;31:522–529. 5. Yasuda K, Tsujino J, Ohkoshi Y, et al. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med 1995;23:706–714. 6. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthros­ copy 2005;21:275–280. 7. Cross MJ, Roger G, Kujawa P, et al. Regeneration of the semitendino­ sus and gracilis tendons following their transection for repair of the anterior cruciate ligament. Am J Sports Med 1992;20:221–223. 8. Hamner DLB, Steiner CH Jr, Hecker ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechani­ cal evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81:549–557. 9. Weiler A, Hoffmann RF, Bail HJ, et al. Tendon healing in a bone tun­ nel. Part II: histologic analysis after biodegradable interference fit fixa­ tion in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135.

Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction* OVERVIEW Hamstring (HS) use for anterior cruciate ligament reconstruction (ACLR) has increased greatly in the past 5 years as improved fixation techniques have allowed stability rates to meet or exceed those of bone–patellar tendon–bone (BPTB) grafts.1 It has been said that the harvest is the most difficult part of HS ACLR2 and may require a learning curve of roughly 50 procedures.3 The primary difficulty is that the intertendinous cross-connections of the semitendinosus (ST) and gracilis (Gr) must be sectioned before the tendon stripper is used to harvest the tendons. If they are not, the tendons can be cut too short to use, necessitating an unplanned switch to a different graft. These crossconnections, however, are significantly posterior to the traditional anterior harvest incision, requiring often-difficult retraction and dissection to reach. The primary benefit of the posterior approach is that it puts the incision in the area of the cross-connections, thus facilitating their visualization and sectioning. The second benefit of the technique is that it allows easier location and identification of the ST and Gr in the posterior incision, where they are separate from each other and easy to find. In the area of the traditional anterior approach, the tendons exist as a single insertional structure, which requires posterior dissection for positive *

The principles and technique described in this chapter are presented in greater detail in the DVD that accompanies this textbook.

identification of individual tendons. This is made more difficult by the close apposition of the superficial fascial sheath anteriorly, whereas posteriorly the fascia is separated from the tendons by fat. The anterior incision, when used in conjunction with the posterior mini-incision, is then used only for tibial tunnel drilling and tibial fixation. It can thus be made much smaller than in the traditional anterior technique, only about 1 inch in length. The author has used this technique continuously without problem for 15 years since devising it after 6 years of experience with the traditional anterior approach.

13 CHAPTER

Chadwick C. Prodromos

ANATOMY The accessory ST tendon is the primary structure leading to premature amputation of the ST tendon after tendon harvesting. This structure is not described in any standard anatomy texts. However, several papers have described it.4–6 It is present in about 70% of patients. Other crossconnections exist variably from the ST and Gr tendons. In some patients they are thin and will be easily cut with a tendon stripper. However, the accessory ST in particular can be almost as thick as the main trunk of the ST. Especially in these cases, the tendon stripper can easily sever the main trunk of the ST, rendering it too short to use. The variability of the anatomy is such that it is difficult to devise a consistent plan for freeing the tendon using the traditional approach, except to run a scissors along both sides of both tendons. 95

Anterior Cruciate Ligament Reconstruction Branches of the saphenous nerve, and indeed its main trunk, are very close by, and saphenous neurapraxia is very common after these dissections. The takeoff of the accessory ST was shown in our studies to be an average of 5 to 6 cm posterior to the tibial crest. Although orthopaedic surgeons rarely operate posteriorly and may be apprehensive about a posterior approach, the posterior approach does not subject neurovascular structures to significant risk. Our cadaver studies showed that the closest neurovascular structure was the popliteal artery, but in eight specimens it was always at least 2.9 cm away from the ST tendon. It was also shielded from the ST tendon by the semimembranosus muscle.

SURGICAL TECHNIQUE

to see posteromedially. The incision should be made directly over it in the popliteal fossa, shading slightly anteromedially (Fig. 13-1). If the ST cannot be felt, the incision can be put into the soft spot in the skin just medial to the midline. The location of this incision is not critical because the tendon can always be found by moving the highly mobile skin in this area. The incision should be made 3 cm in length initially but need only be 2 cm in length once experience is gained. It should be put within or parallel to a skin crease. After the dermis is incised with a #15 blade, the subcutaneous tissue is opened by spreading with Metzenbaum scissors.

Finding the Semitendinosus

The patient is positioned supine. We use a lateral post rather than a circumferential leg holder, but the latter can be used if the surgeon desires.

An index finger should probe the incision, fishing the tendon out bluntly. If it is not easily found in this manner, two Senne retractors can be used to open the incision, and the tendon can be found under direct visualization. Once the tendon is identified, a right-angle clamp is passed around it. A ¼-inch Penrose drain then captures it and is loosely clamped (Fig. 13-2).

Making the Posterior Skin Incision

Finding the Semitendinosus Insertion

The ST is the most prominent tendinous structure in the popliteal fossa and runs just medially to the midline. The affected lower extremity is externally rotated, and the knee is flexed about 30 degrees. The surgeon bends over the leg

Once the tendon is identified, the surgeon runs his or her index finger under it to its tibial insertion. This may necessitate opening the fascia posteriorly slightly with Metzenbaum scissors. At the insertion the surgeon can verify that he or

Patient Positioning

Sartorius Semitendinosus Semimembranosus Gracilis Mini-incision

Tibial nerve Popliteal vein Popliteal artery

FIG. 13-1 The semitendinosus (ST) and gracilis (Gr) tendons are shown posteriorly, where they are separate from each other and easy to identify.

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Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction

FIG. 13-2 The semitendinosus (ST) tendon is isolated in the posterior mini-incision.

13

FIG. 13-3 The semitendinosus (ST) is isolated in the anterior mini-incision.

she indeed has the ST and not the Gr, which is sometimes found first. The ST is the most distal tendinous insertion in the pes. If the Gr is found first, the surgeon can find the insertion of the ST adjacent to the insertion of the Gr. The surgeon can then pull his or her finger back to the posterior incision to find the ST there.

Making the Anterior Incision The skin is tented just anterior to the posteromedial tibial border by the index finger inserted in the posterior incision under the ST. The surgeon makes a 2-cm longitudinal incision here with a #15 blade. This area is then opened with Metz scissors, and the superficial fascia is incised carefully to avoid scoring the tendons.

FIG. 13-4 The gracilis (arrow) is isolated in the anterior mini-incision.

Identifying the Semitendinosus in the Anterior Incision

Harvesting the Semitendinosus and Sectioning the Accessory Semitendinosus

A right-angle clamp is inserted in the anterior incision and passed around the ST tendon to grasp a ¼-inch Penrose drain (Fig. 13-3). The surgeon's other index finger is still under the tendon and guides the clamp. The surgeon may insert the short end of an Army-Navy retractor and identify the tendon by direct visualization. A ¼-inch Penrose is then passed around the tendon and clamped with a right angle.

A small, closed corkscrew tendon stripper is passed around the ST near its common insertion with the Gr without disrupting it. It is gently but firmly passed proximally with a firm rotary, back-and-forth motion. Resistance will be felt when the stripper encounters the accessory ST (Fig. 13-5). At this point the stripper should be carefully advanced another 1 or 2 cm, taking care not to apply excessive force. Two Senne rakes are then placed in the posterior incision, and the mobile skin is moved anteriorly over the head and neck of the tendon stripper to expose them while maintaining firm pressure on the stripper. The surgeon uses a forceps and Metz scissors to dissect the filmy tissue off the stripper neck. Sitting directly on the neck of the tendon stripper will be the accessory ST, with the main trunk of the tendon extending outward from the corkscrew (Fig. 13-6). This accessory ST should be cut with either a Metz scissors or a #15 blade. The stripper will now slide freely

Identifying the Gracilis Using the ST as a guide, the Gr can be found either in the posterior or anterior incision (Fig. 13-4) either before or after the ST is stripped proximally. If the ST is 30 cm or longer, we do not harvest the Gr but rather use a four-strand ST graft.

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Anterior Cruciate Ligament Reconstruction

Sartorius Gracilis Semimembranosus sling Main semitendinosus

Incision Incision

Accessory semitendinosus

FIG. 13-5 The tendon stripper is shown as it is about to deliver the accessory semitendinosus crossconnection out of the posterior miniincision.

need only slide his or her index finger along the tendon with the tendon stripper via the posterior incision. The surgeon can guide it so that it does not get caught up on fascia but rather glides along the tendon. The surgeon can also effectively dilate the path the tendon stripper takes proximally, allowing it to pass further until the full length of the tendon is harvested.

Freeing the Tendon Distally

FIG. 13-6 The accessory semitendinosus (ST) sits on the neck of the tendon stripper outside of the posterior incision, where it can be easily sectioned under clear visualization.

toward the proximal. It should be pushed until the tendon is freed proximally while countertension is maintained with a ¼-inch Penrose or index finger near its insertion. Once freed, the ST is delivered out the anterior incision.

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With the two (or one) tendons delivered out the anterior incision, the periosteum is scored parallel and to the deep side of the tendon(s) (Fig. 13-7). An additional 2 cm of periosteum can then be harvested in line with the insertion, essentially prolonging it with tough tissue that also has the benefit of the growth factors found on its cambium layer for intratunnel fixation and ingrowth.

Graft Preparation The tendon(s) is given to the assistant at the back table for cleaning and measuring.

What if the Tendon Stripper Gets Caught in the Thigh?

Time of Harvest

This can happen at the semimembranosus sling or at the fanning-out of the ST. If firm resistance is met, the surgeon

The harvest can usually be accomplished in less than 10 minutes. However, occasionally the harvest will be a little

Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction

13

Problem 2: Tendon Identification When only an anterior incision is used, its location must be estimated from the tibial tubercle. When the fascia is lifted, it can be difficult to clearly identify which pes tendon is which or even where the tendon starts and the fascia ends—particularly in large patients—because the ST and Gr insert as a common tendon. As they course distally, they cease being separate structures at roughly the posteromedial tibial border. Definite verification involves posterior dissection to this point or beyond where the anatomy is clearer. This can be time consuming and also increases the risk of saphenous neurapraxia. FIG. 13-7 The harvested semitendinosus/gracilis (ST/Gr) tendon is seen with periosteum extending the common insertion onto the tibia.

more difficult. In these cases the surgeon should take time to find and free the tendons safely. The greatest virtue of this technique is that the bi-incisional access allows the surgeon to accomplish even the most difficult harvests safely. However, patience and more time are required for some harvests, and the surgeon should not be in a rush if the harvest is problematic. It is still possible to cut the tendon short if the surgeon attempts to force rather than finesse a difficult harvest.

HARVEST PROBLEMS WITH THE TRADITIONAL APPROACH AND SOLUTIONS USING THE COMBINED POSTERIOR/ANTERIOR MINI-INCISION APPROACH Problem 1: Premature Tendon Amputation The chief danger in the harvest is that the intertendinous cross-connections, which variably occur, will not be adequately sectioned prior to harvesting with the tendon stripper as described earlier, resulting in premature tendon amputation. These cross-connections can be difficult to visualize from the anterior approach.

Solution The posterior mini-incision facilitates identification of the intertendinous cross-connections by putting the incision where these structures exist—posteromedially. The tendon stripper delivers the cross-connections out of this incision, where they can be sectioned under direct vision, instead of in the depths of the anterior incision, where both they and neurovascular structures are difficult to see.

Solution The pes tendons exist as separate structures roughly 1.5 cm apart posteriorly. The ST can usually be easily palpated posteriorly, which is not the case anteriorly. A small posterior incision placed directly over the ST and slightly anteromedial to it allows ready identification of the ST. Running an index finger under this tendon precisely allows placement of the anterior incision over the tendon insertion by tenting the skin at this point.

Problem 3: Hang-Up of the Tendon Stripper in the Distal Thigh at the Fanning-Out of the Semitendinosus or Semimembranosus Sling Even if the cross-connections are cut, the tendon stripper can still cut the tendon short at this point. This point is too high up in the thigh to be reached from a traditional anterior approach.

Solution If marked resistance to the tendon stripper is met in the thigh, an index finger can be inserted up the thigh through the posterior incision to free it, after which the stripper will easily pass.

Problem 4: Saphenous Nerve Trauma and Numbness Numbness has been shown to occur in more than half of patients after ACL surgery.7,8 Most of the time it is not significantly bothersome to the patient. However, it is bothersome to occasional patients. In addition, there is evidence that stiffness and complex regional pain syndrome (formerly reflex sympathetic dystrophy) are more common with significant nerve trauma after knee surgery.

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Anterior Cruciate Ligament Reconstruction

Solution The posterior mini-incision diminishes saphenous nerve trauma in three ways. First, the posterior mini-incision is posterior to the saphenous nerve, where there is no danger of trauma to it or its branches. Second, the anterior incision is made much smaller because the posterior incision allows it to be precisely placed. This decreases the chances that a saphenous branch such as the infrapatellar branch will be cut. Third, because the tendon stripper delivers the crossconnections externally out of the posterior incision, there is no need to dissect and retract anteriorly. This diminishes trauma to the saphenous nerve and its branches from retraction and dissection. We have found that if only the short end of an Army-Navy is used for retraction, and if very little retraction is done, the incidence of numbness is much less than if longer retractors are used or vigorous retraction is performed.

Problem 5: Cosmesis Cosmesis is not generally a significant problem, but our studies have shown4 that cosmesis does matter to many patients, especially to females.

Solution The posterior incision is hidden and becomes essentially invisible. The anterior incision is much smaller, usually only 1 inch or smaller, and it is the only incision the patient sees. It also becomes very hard to detect by 1 year after surgery.

Problem 6: Harvest in Large Patients It has been suggested that allografts are a better choice than HS in large or obese patients because of the difficulty of the harvest.

Solution The presence of a posterior incision removes the difficulty in finding, identifying, and freeing the tendon. It is more difficult than in a slender person but can always be accomplished. The usually 1-inch incisions should be made a little larger, but no other technical modifications are necessary.

CLINICAL EXPERIENCE We have used this technique continuously and exclusively since 1991. Harvested ST tendons tend to vary between 24 and 34 cm in length. Depending on ST length, we will either perform a 4ST or 2ST/2Gr graft. Roughly 85% of our grafts are 2ST/2Gr. We have never had tendons cut

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too short to produce a four-strand graft. We have had no complications referable to this approach, neurovascular or otherwise. In addition to essentially eliminating the risk of cutting tendons short, use of this approach has also reduced harvest time. Numbness was reduced initially with the short incision and has now been almost completely eliminated by the minimal retraction technique. Cosmesis and patient satisfaction have been excellent.

WHO SHOULD USE THIS TECHNIQUE? This technique is particularly desirable for the new or occasional HS harvester and has proven valuable to those in training programs. However, it will also facilitate the harvest and improve cosmesis for most experienced HS surgeons who now use the traditional approach—as it did for the author, who began to use it after fellowship training in hamstring ACLR and 6 years of practice performing the standard technique. Initially the incisions can be made larger. Cosmesis will still be better than with the traditional approach. The incisions can be reduced with experience if the surgeon wishes. 4HS grafts have now been shown to have excellent stability rates1 (see Chapter 69), and the harvest has been shown to be the chief obstacle to use of the technique. With this approach the surgeon can accomplish the harvest safely and reliably so that harvesting is no longer a significant factor in graft choice.

References 1. Prodromos CC, Joyce BT, Shi KS, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 2. Williams RJ, III, Hyman J, Petrigliano F, et al. Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg Am 2004;86A:225–232. 3. Howell SM. Principles of hamstring fixation. In: ACL reconstruction: from graft choices and fixation to single and dual tunnel techniques. Instruction course presented at the meeting of the Arthroscopy Association of North America, Vancouver, BC, Canada, May 2005. 4. Prodromos CC, Han YS, Keller BL, et al. Posterior mini-incision technique for hamstring anterior cruciate ligament reconstruction graft harvest. Arthroscopy 2005;21:130–137. 5. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev 1991;20:1085–1088. 6. Pagnani MJ, Warner JJ, O'Brien SJ, et al. Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565–571. 7. Portland GH, Martin D, Keene G, et al. Injury to the infrapatellar branch of the saphenous nerve in anterior cruciate ligament reconstruction: comparison of horizontal versus vertical harvest site incisions. Arthroscopy 2005;21:281–285. 8. Spicer DDM, Blagg SE, Unwin AJ, et al. Anterior knee symptoms after four-strand hamstring tendon anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2000;8:286–289.

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction INTRODUCTION The middle third of the patella tendon (bone– tendon–bone) is frequently used as a graft to replace a torn anterior cruciate ligament (ACL). A segment of bone is taken from the tibial tuber­ cle. It is left attached to the distal end of the patella tendon. A segment of bone is taken from the inferior pole of the patella. It is left attached to the proximal end of the tendon. The graft is reversed and is pulled upward through the tibial tunnel, across the joint, and into the femoral tun­ nel. The leading end of the graft (the bone plug that was taken from the tibia) is fixed to the femur using an interference screw. The trailing end of the graft (the patella portion) is fixed in the tibial tunnel using an interference screw. Extra pieces of bone that were trimmed from the bone plugs are placed in the patella defect. The edges of the patella tendon are closed.

SKIN INCISION A vertical skin incision is made medial to the tib­ ial tubercle approximately 0.5 cm medial to the medial edge of the patella tendon (Fig. 14-1). The upper end of the incision begins near the level of the joint line. The incision is extended distally to the level of the lower end of the tibial tubercle, approximately 6 to 8 cm below the joint line. Do not place this vertical incision in the midline of the knee: this leaves an unsightly scar, and it is difficult to reach the tibial tunnel from this midline position. This anteromedial

incision is placed distally, which is necessary to allow positioning of the tibial guide and drilling of the tibial tunnel (Fig. 14-2). It is not necessary to extend the incision very far proximally beyond the level of the joint; when the knee is extended and a single spike retractor is placed at the superior pole of the patella, the patella is pushed distally. The patella can thus be reached through this short, distally placed incision. Bupivacaine 0.5% with epinephrine 1:200,000 is infiltrated subcutaneously along the edges of the incision. Dissection is carried out through the superficial fascial layer to reach the deep fascial layer.

14 CHAPTER

Bertram Zarins

EXPOSURE Incise the deep fascial layer lengthwise over the center of the underlying patella tendon. This deep fascial layer is thin but becomes even thinner over the tibial tubercle. Divide the deep fascial layer proximally to the level of the upper portion of the patella (Fig. 14-3). This exposes the under­ lying patella, patella tendon, and tibial tuberosity. Enlarge the prepatella bursa to gain access to the patella.

TAKING THE GRAFT The average width of the patella tendon is about 30 mm. An approximately 10-cm width of ten­ don, or one-third, is taken as a graft. A ⅜-inch osteotome (which is about 9 mm wide) can be 101

Anterior Cruciate Ligament Reconstruction

FIG. 14-1 The skin incision is made on the medial aspect of the right knee. The incision begins at the joint line and extends distally about 6 to 8 cm. Do not place the incision over the center of the tibial tubercle.

FIG. 14-3 The deep fascia is incised over the center of the tibial tubercle, patella tendon, and patella.

FIG. 14-2 The skin incision has been placed distally and medially to allow proper placement of the tibial drill guide.

used as a template for judging the width of the graft and bone plugs. An osteotome 3 cm in length is used to make two par­ allel vertical cuts in the tibial tubercle to fashion a 9-cm-wide bone plug (Fig. 14-4). The ⅜-inch osteotome is used to make a transverse cut in the bone at the level of the distal end of the graft. The resulting bone plug is about 30 mm in length. Use the wide osteotome to extend the cuts in the tibial tubercle proximal to the tibial tubercle almost to the level of the joint; otherwise, the plug might crack proximally near the tendon-bone junction. Drill a single small hole in the distal end of the tibial bone plug, slightly less than 1 cm from 102

FIG. 14-4 A 3-cm-wide osteotome is used to make two parallel cuts in the tibial tubercle to fashion a 9-mm-wide bone plug.

the end of the tibial bone plug (Fig. 14-5). Pass a single suture of #5 Fiberwire through the tibial bone plug. Apply traction to the tibial bone plug, and slightly incise the superficial surface of the patellar tendon in line with the tibial tubercle bone plug. Use your finger to sepa­ rate the edges of the patella tendon graft from the adjacent patella tendon (Fig. 14-6). This blunt dissection avoids cutting fibers of the patella tendon graft.

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction

14

FIG. 14-7 The single spike retractor has been placed at the superior pole of the patella and is used to lever the patella distally. The cutting current of the electrocoagulation devices is used to mark the proposed bone cut. FIG. 14-5 A hole is drilled in the bone plug that was taken from the tibial tubercle.

proposed cuts in the patella using electrocautery, which will achieve an 11-mm-wide plug that will be about 30 mm long (Fig. 14-8). Drill the corners of the graft to create round stress risers. Drill two small holes in the patella bone plug for later passage of sutures. Make the remaining cuts in the patella using the fine reciprocating saw to a depth of 1 cm (Fig. 14-9). To loosen the bone plug from the patella, use a ¼­ inch-wide curved osteotome inserted into the kerf at the superior end of the plug (Fig. 14-10). Never insert the osteotome into the medial or lateral kerfs along the edges of the patella bone plug, which will likely fracture the patella. Apply tension to the distal end of the graft, and

FIG. 14-6 The patella tendon is split in line with its fibers using a finger.

Insert a single spike retractor under the proximal edge of the skin incision. The prepatella bursa provides space to reach the superior pole of the patella. The spike of the retractor is set into the quadriceps tendon at the superior pole of the patella and is used to lever the patella distally (Fig. 14-7). Using the cutting current of the cautery device, mark the line of the proposed first cut in the patella (see Fig. 14-7). Use a fine reciprocating saw to cut a slot in the patella for a length of about 25 mm and to a depth of 1 cm. Insert a metal ruler into this kerf (the cut made by a saw) and use it as a guide from which to measure. Using the ⅜-inch-wide osteotome as a template, mark the

FIG. 14-8 A ruler has been placed in the kerf. A ⅜-inch-wide osteotome is used as a template, and electrocautery is used to mark out a bone plug 11 mm wide and 25 mm long.

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Anterior Cruciate Ligament Reconstruction

FIG. 14-9 After the corners of the graft have been drilled, a fine reciprocating saw is used to make superior and then lateral cuts in the bone plug.

FIG. 14-11 A ¼-inch curved osteotome is used from below to create a 1­ cm-thick bone plug from the patella.

FIG. 14-12 A sizer is used to fashion an 11-mm-diameter bone plug that was taken from the patella (the trailing end of the graft). FIG. 14-10 A ¼-inch curved osteotome loosens the upper end of the bone plug. Never put the osteotome into the medial or lateral kerfs to prevent fracturing the patella.

use the ¼-inch-wide curved osteotome from below (starting at the inferior pole of the patella) to lift the patella bone plug from its bed (Fig. 14-11).

FASHIONING THE GRAFT Use a bone cutter or rongeur to remove excess bone from both bone plugs to fashion a 9-mm-diameter bone plug from the tibial tubercle and an 11-mm-diameter bone plug from the patella (Fig. 14-12). Use a bone sizer to com­ press any excess cancellous bone. Do not use the bone sizer to compress cortical bone; doing so may fracture the patella. Place the extra pieces of bone into the defect in 104

the patella. Close the deep fascial layer over the patella to prevent the bone pieces from falling out. Leave the edges of the patella tendon defect open for the time being. At a side table, fashion the graft. To prevent dropping the graft, keep the suture that is attached to the graft wrapped around your little finger. Pass #5 Fiberwire sutures through each of the two holes and clamp the ends of the sutures. Use a 2–0 Vicryl running suture to tubularize the tendon at the end attached to the tibial bone plug (which will become the leading end of the graft) (Fig. 14-13). This will make it easier to place the interference screw into the femoral tunnel. Measure the total length of the graft and the lengths of the bone plugs. Use a colored marker pen to mark the bone-tendon junctions of the graft. Also mark the tendon side of the trailing end of the patella bone plug; this will aid in positioning the tibial interference screw on the opposite (cancellous) side of the plug (Fig. 14-14).

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction

14

FIG. 14-14 The mid-third patella tendon graft is about 10 cm long. The graft incorporates (in continuity) segments of bone from the inferior pole of the patella (9 � 30 mm) and from the tibial tubercle (11 � 25 mm). The bone-tendon junctions have been marked. The trailing end of the graft (tendon side) is marked. FIG. 14-13 The tendon of the leading edge of the graft is tubularized to allow easy placement of the interference screw in the femoral tunnel.

The final length of the graft is about 10 cm long. The leading end of the graft (taken from the tibial tubercle) is 9 mm in diameter and about 30 mm long. The trailing end of the graft (formerly patella) is 11 mm in diameter and about 25 mm long.

CLOSURE After the graft has been fixed, flex the knee to 90 degrees to achieve equal tension on the medial and lateral thirds of the patella tendon. Close the defect in the patella tendon using interrupted #0 Vicryl figure-eight sutures. Close the deep fascial layer.

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15

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

John P. Fulkerson

INTRODUCTION

CHAPTER

The central quadriceps has been used for anterior cruciate ligament reconstruction (ACLR) for more than 25 years.1,2 Stability results are similar to those with other autograft alternatives, but patients experience less pain and reach rehabilitation landmarks sooner.3 Staubli et al4,5 have studied the anatomy and biomechanical properties of the quadriceps tendon. We became interested in this ACL graft in the early 1990s, first using it with bone6 but later discovering that it is a desirable free tendon graft option7 for ACLR. We wanted to avoid the risk of postoperative problems noted with bone–tendon–bone–patella tendon graft harvest,8,9 were concerned about subtle weakness after taking out the medial hamstring tendons for ACLR in young athletes,10 and continue to worry about the possibility of prions in allograft tissue. We wanted to avoid these risks by using the central quadriceps free tendon (CQFT) for our ACLR. We confirmed and later reported the strength of the quadriceps tendon after harvesting the graft.11 Our experience has remained very positive as we begin our 10th year with the CQFT graft. Also, patients frequently come into our office impressed with how little postoperative pain and difficulty they have compared with bone–tendon–bone and hamstring ACLR patients they encounter in physical therapy, as noted by Joseph et al3 in their short-term recovery study of ACLR patients.

106

TECHNIQUE We use the CQFT graft in all patients except those who specifically request another graft type, usually an allograft. To harvest the CQFT, make a short 1.5- to 2-inch incision from the mid proximal patella upward (Fig. 15-1), and retract to view the quadriceps tendon. Retract slightly medially and note the vastus medialis obliquus (VMO). The graft should be taken preferentially from the thicker medial part of the quadriceps tendon but started proximally by retracting upward to the proximal VMO where the first incision is placed. Use a #10 scalpel blade and draw it distally at a 6- to 7-mm depth (just slightly less than the breadth of a #10 blade). The medial border of the graft then will usually be about 5 to 8 mm from the VMO at the level of the proximal patella. Place the second incision 9 to 11 mm lateral to the first at the level of the proximal patella and extend it proximally, keeping the blade at 90 degrees to the quadriceps tendon and at a 6- to 7-mm depth (the quadriceps tendon is about 9 mm thick). After placing these incisions, place the tip of a hemostat at the desired depth beneath the CQFT, and spread the hemostat to separate the CQFT posterior fibers within the substance of the quadriceps tendon. This leaves a thin 1 mm of posterior quadriceps tendon attached to the synovium of the suprapatellar pouch. If the joint has been entered, the defect is then easily closed with this remaining tissue and synovium.

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

FIG. 15-1 Exposure for quadriceps tendon graft harvest.

FIG. 15-2 Release of the proximal end of the quadriceps tendon graft.

Properly done, you now have a piece of tendon that is about 6 to 7 mm thick and includes portions of the rectus and intermedius tendons. Note that there is a cleavage plane between these two components of the quadriceps tendon. Keep spreading at the desired depth, and then dissect the tip of the graft at its insertion into the patella and release it without cutting any of the surrounding quadriceps tendon. Grasp the released end of the quadriceps tendon with a uterine T clamp, and further dissect it proximally using a combination of blunt stripping and careful sharp dissection. We usually place two whipstitches12 with at least one Fiberwire (Arthrex, Naples, FL) in the released end and use this for traction during the dissection. Release the CQFT graft proximally at 7 to 8 cm from the distal end. May scissors work best in our hands (Fig. 15-2).

the pouch—you have a good 7 mm of tendon thickness to work with in almost every patient, but do not cut any deeper. If you do, cut all water flow, finish the harvest leaving the posterior fibers of quadriceps tendon, and run a continuous Vicryl suture along the synovium to close the defect before resuming arthroscopy. Releasing the graft distally is easiest with a #15 scalpel blade. While retracting with the hemostat, you can define the insertion point of the graft on the patella nicely and release only the graft portion of the quadriceps tendon from the top of the patella. A hemostat works well for defining the posterior border of the graft spread generously. If you do not obtain a thick-enough graft depth initially, place the hemostat a little deeper and define a larger, thicker graft as needed. The author prefers to use almost entirely blunt dissection after defining the borders, but a few careful clips with Metzenbaum scissors to aid the graft removal is usually helpful. Visualize all sides of the graft while stripping it out. Keep the knee flexed to 90 degrees, with tension on the quadriceps tendon, during the entire harvest. Use a uterine T clamp to grasp the end of the graft and then put #5 whipstitches in the free end, before stripping the graft proximally, to apply tension for the stripping. Use Mayo scissors to release the graft proximally under direct vision while retracting skin proximally and pulling the graft distally. As you release it, be careful not to flip the graft back into your face mask with the tension. Take the graft to the back table and keep it under tension for whipstitching the other end, sizing it, and preparing it for placement in the knee.

TROUBLESHOOTING CENTRAL QUADRICEPS FREE TENDON HARVEST At first, harvesting the CQFT graft can seem a bit daunting until the surgeon becomes familiar with the anatomy, depth, and extent of the tendon. It is a very large, thick, and forgiving graft source. The quadriceps tendon is thickest near the VMO, so the harvest should be as close to the VMO as possible while avoiding all but the proximal muscle fibers of the VMO. Thus, think of the harvest as midline, starting at the proximal central aspect of the quadriceps tendon but 1 or 2 mm medially. When first harvesting the graft, be sure to make an adequate incision. The incision gets smaller with experience. Define the graft borders carefully and try to avoid entering

15

107

Anterior Cruciate Ligament Reconstruction

FIG. 15-3 Sizing of the quadriceps tendon graft.

FIXATION OF THE CENTRAL QUADRICEPS FREE TENDON GRAFT We take the CQFT graft to the back table and place two sets of #5 whipstitches in each end using a combination of Ethibond or Ticron and Fiberwire. McKeon et al have shown that it is not necessary to place more than two whipstitch throws in each side of the tendon.12 Use sizing cannulas (Fig. 15-3) to determine the size of the graft and the tunnels you will drill in the tibia and femur. In most cases, the graft will fit snugly into 8- or 9-mm tunnels. Next, place a circumferential mark on the graft at the point where it will exit the femoral socket (we like 2 cm of CQFT in the femoral socket). We prefer an Endobutton on the femoral end (Fig. 15-4), tying the #5 sutures (four strands off the end of the graft) after measuring the depth

FIG. 15-5 Bottom view of the central quadriceps free tendon (CQFT) graft in the tibial tunnel.

of the femoral tunnel such that the distance from the Endobutton to the marked femoral socket exit point on the graft is the same as the tunnel length, measured with the Endobutton depth gauge. Tie the sutures together (we use a Graftmaster to hold the graft and Endobutton during this process) with the knot just adjacent to the tendon graft (tying it elsewhere may cause problems in full deployment of the Endobutton). We pull the graft into the tunnels and deploy the Endobutton in the usual fashion, using a #5 suture and then a #2 in the other end to flip the Endobutton after it is through the lateral femur.

Femoral socket

#5 leading suture

#2 trailing suture

⭓7 cm

Tibial tunnel/socket screw/washer FIG. 15-4 Quadriceps tendon with Endobutton.

108

Knot close to the graft to avoid problem with Endobutton

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

15

We use a biointerference screw that is one size larger than the tunnel size for tibial side fixation. After thoroughly cycling the graft in the knee and while maintaining tension on the graft, flex the knee 20 degrees and insert the biointerference screw over a guidewire that is held in place just anterior to the graft in the tibial tunnel. Be sure not to push the screw and graft, but rather advance it by turning only after seating the screw. We prefer to have the tip of the screw 5 to 8 mm back from the intercondylar notch and recommend viewing the screw/graft construct from below to confirm proper placement (Fig. 15-5). A button may be tied over the tibial tunnel for added fixation if desired.13 We have been pleased with these fixation methods (Figs. 15-6 and 15-7).

FIG. 15-7 Quadriceps tendon with bone or biointerference disk and screw.

References

FIG. 15-6 Central quadriceps free tendon ACL reconstrution.

1. Marshall JL, Warren RF, Wickiewicz TL, et al: The anterior cruciate ligament: a technique of repair and reconstruction. Clin Orthop Relat Res 1979;Sep:97–106. 2. Blauth W: Die zweizugelige Ersatzplastik des Vorderen Kreuzband der Quadricepssehne. Unfallheilkunde 1984;87:45–51. 3. Joseph M, Fulkerson J, Nissen C, et al: Short-term recovery after anterior cruciate ligament reconstruction: a prospective comparison after three autografts. Orthopedics 2006;29:243–248. 4. Staubli HU, Schatzmann L, Brunner P, et al: Quadriceps tendon and patellar ligament: cryosectional anatomy and structural properties in young adults. Knee Surg Sports Traumatol Arthrosc 1996;4:100–110. 5. Staubli HU, Schatzmann L, Brunner P, et al: Mechanical tensile properties of the quadriceps tendon and patellar ligament in young adults. Am J Sports Med 1999;27:27–34. 6. Fulkerson JP, Langeland R: An alternative cruciate reconstruction graft: the central quadriceps tendon. Arthroscopy 1995;11:252–254. 7. Fulkerson J: Central quadriceps free tendon for anterior cruciate ligament reconstruction. Oper Tech Sports Med 1999;7:195–200. 8. Viola R, Vianello R: Three cases of patella fracture in 1320 anterior cruciate ligament reconstructions with bone-patellar tendon-bone autograft. Arthroscopy 1999;15:93–97. 9. Sachs RA, Daniel DM, Stone ML, et al: Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760–765. 10. Marder RA, Raskind JR, Carroll M: Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction. Patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478–484. 11. Adams D, Mazzocca A, Fulkerson J: Residual strength of the quadriceps versus patellar tendon after harvesting a central free tendon graft. Arthroscopy 2006;22:76–79. 12. McKeon B, Heming J, Fulkerson J, et al: The Krackow whipstitch: a biomechanical evaluation of changing the number of loops versus the number of sutures. Arthroscopy 2006;22:33–37. 13. Nagarkatti DG, McKeon BP, Donahue BS, et al: Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation. Am J Sports Med 2001;29:67–71.

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16 CHAPTER

Alberto Gobbi Ramces Francisco

110

PART C HAMSTRING GRAFT CONFIGURATIONS

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft INTRODUCTION A wide variety of techniques and graft types are now available for the reconstruction of the anterior cruciate ligament (ACL). Years of clinical and surgical experiences gained by surgeons together with the development and modification of the various instrumentations have greatly contributed to the better results currently reported in literature. However, disagreement persists among experts with regard to the ideal technique and graft type most suitable for reconstruction. Currently, most surgeons use either the hamstring graft or the bone–patellar tendon– bone (BPTB) graft for ACL reconstruction. Previous studies have demonstrated the advantages and disadvantages of using one type of graft over the other. However, recent investigations have confirmed that comparable outcomes can be achieved with either of these two graft types.1–3 Inherent advantages cited with the use of hamstring grafts include its strength, decreased incidence of donor site morbidity, easier rehabilitation, smaller incisions, and better cosmesis.1,2,4 With BPTB graft, the strong bone-to-bone fixation and the faster healing achieved with the bone plugs at the graft’s end1,5 remain important advantages. In this chapter, we describe the technique of using a quadrupled semitendinosus tendon graft harvested with a bone block for the reconstruction of a torn ACL.

Studies have demonstrated that this type of graft configuration is capable of producing a clinically stable construct that allows recovery of normal limb strength and early return to active sports and results in low donor site morbidity.

SCIENTIFIC RATIONALE FOR A QUADRUPLED CONSTRUCT Hamstring grafts have gained popularity among surgeons due to the well-documented higher donor site morbidity when patellar tendon graft is used.6–8 Although prospective randomized studies comparing patellar tendon and hamstring grafts demonstrated no significant difference in final outcome, the apparent advantages offered by hamstring grafts remain appealing to surgeons. Previous concerns related to the hamstring tendon’s viability have long been dismissed, and studies comparing different graft types and configurations have demonstrated that failure load and stiffness values for four-stranded hamstring tendon grafts are higher than values reported for the natural ACL (2160N, 242 N/mm), 10-mm-wide patellar tendon grafts (2977N, 455 N/mm), and 10-mm-wide quadriceps tendon grafts (2353N, 326 N/mm).9,10 On the other hand, concerns related to hamstring graft incorporation within the tunnel was addressed with Morgan’s11 introduction of an “all inside” technique using bone–hamstring– bone composite graft. Therefore to address the

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft concerns related to morbidity and delayed graft incorporation, we developed a technique that combines the advantages of a decreased donor site morbidity by using only one hamstring tendon (semitendinosus) with the possibility of achieving faster graft–tunnel incorporation by including a bone block with the distal limb of the semitendinosus tendon during harvest.1,12,13

SURGICAL TECHNIQUE The surgery can be performed under spinal anesthesia or general anesthesia. The patient is positioned supine on the operating table, and the tourniquet is placed as high as possible on the thigh to allow sufficient distance from the exit point of the Beath needles in the lateral thigh. The tourniquet is inflated only during graft harvest. A thigh support is placed at the level of the tourniquet cuff while a foot bar is positioned at the end of the table to enable the knee to be fixed at 90 degrees of flexion during surgery while at the same time still allowing free range of motion. A 3-cm vertical incision centered approximately 5 cm below the medial joint line, midway between the tibial tubercle and the posteromedial aspect of the tibia, is performed. The sartorial fascia is incised, and the semitendinosus tendon is dissected and detached proximally with a tendon stripper. The distal limb of the tendon is detached along with a tibial bone plug and periosteum with the use of an osteotome. To achieve the desired 7-cm quadrupled graft construct (2 cm inserted in the femoral tunnel, 3 cm intraarticular, and 2 cm inserted in the tibial tunnel), the required minimum tendon length would be 28 cm (range 28–30 cm) (Fig. 16-1). Alternatively, semitendinosus tendons that are shorter than 28 cm can be prepared in a tripled configuration.

Graft Preparation Quadrupled Semitendinosus Graft At the back table, all the muscle tissues attached to the tendon are removed with the use of a curette. Once devoid of excess tissues, the tendon is folded in a quadrupled fashion with the bone plug tied outside. Prior to suture placement on the tendon construct, the depth of the femoral tunnel is measured to determine the appropriate size of the Endobutton-CL

FIG. 16-1 The semitendinosus tendon harvested with a bone block attached on one end. The ideal length for the graft should be at least 28 cm to allow the preparation of a quadrupled construct.

16

(Smith & Nephew, Endoscopy, Andover, MA) to be used. Once the proper size is chosen, the Endobutton is then positioned in the quadrupled construct’s end where the bone block is located. Both ends of the graft are then whipstitched using #5 nonabsorbable sutures. A polyester tape is then knotted at the other end of the graft (Fig. 16-2, A, B). Measurement of the graft diameter follows, using 0.5-mm increment sizers to match this with the diameter of the femoral and tibial tunnels. Once in place, the grafts are pretensioned and preconditioned prior to fixation with cyclical flexion and extension of the knee under maximum manual tension.1,6

Tripled Semitendinosus Graft (Alternative Option for Short Semitendinosus Grafts) Harvested semitendinosus tendons with a total length of less than 28 cm can be prepared in a tripled configuration. Once the excess tissues are removed, both ends of the semitendinosus tendon are whipstitched using #5 nonabsorbable sutures (Fig. 16-3, A). The tendon is then folded in three parts (three limbs) to determine the graft’s length and to approximate the size of the Endobutton-CL to be used. In general, we usually use either a 20- or 25-mm EndobuttonCL, considering that we have a tunnel length of about 40 to 45 mm. On the end of the graft where the bone plug is located, the free ends of the suture are used to tie a knot around the Endobutton-CL so that it becomes attached to the graft (Fig. 16-3, B). The other end of the graft is then passed through the loop of the EndobuttonCL as the tendon is folded in three parts. After passing through the Endobutton-CL, the suture at the free end of the graft is separated and positioned in such a way that it would catch the looped tendon at the opposite end (Fig. 16-3, C). With this configuration the diameter of this tripled semitendinosus is measured to make sure that it corresponds with the femoral and tibial tunnels. Prior to the final fixation, routine pretensioning and preconditioning of the graft are performed.

Arthroscopic Anterior Cruciate Ligament Reconstruction A standard anterolateral portal is created through which the arthroscope is inserted followed by an anteromedial portal where instruments can be introduced. While the graft is being prepared at the back table, tunnel preparations are completed. The tibial tunnel is prepared with the Acufex aimer set at 45 degrees with 70 degrees of inclination from the sagittal plane. During tibial tunnel reaming, a bone plug is obtained through the coring system used. On the other hand, the femoral tunnel is drilled in the 10:30 position for the right knee. Femoral fixation is achieved with the Endobutton connected to the graft while tibial fixation is obtained with an 8-mm titanium Fastlok device 111

Anterior Cruciate Ligament Reconstruction Endobutton

Bone plug 9–10 mm

BONE Quadrupled semitendinosus autograft

A

FIG. 16-2 Diagram (A) and actual quadrupled semitendinosus construct with Endobutton on one end and polyester tape in the other end (B). The bone block is positioned and stitched outside the graft.

Bone plug

Semitendinosus autograft

A Endobutton

Bone plug

Semitendinosus autograft

B Endobutton

Bone plug

Tripled semitendinosus autograft

C FIG. 16-3 A, Diagram of the semitendinosus tendon with both ends sutured. B, Endobutton-CL is knotted on the end where the bone plug is located; the free end of the graft is then passed through the Endobutton-CL to form the three limbs. C, The free ends of the suture are separated and hooked around the opposite loop to complete the configuration.

(Neoligaments, Leeds, United Kingdom), which is also connected to the graft with a quadrupled polyester tape. Finally, the bone block previously obtained from reaming the tibia is press-fitted in the tibial tunnel (Fig. 16-4). Postoperatively, rehabilitation is commenced according to the protocol described by Rosenberg and Pazik.14 112

Clinical Results In a previous study10 of 100 patients who underwent ACL reconstruction using this technique, it was demonstrated that the average postoperative VAS pain score was 5 (range 2–7), with 90% of the patients discharged within 24 hours

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft

Endobutton-CL Bone block attached to ST Quadrupled semitendinosus Bone block Polyester tape Fastlok tibial fixation

FIG. 16-4 Diagram of quadrupled semitendinosus with bone (QSTB) anterior cruciate ligament reconstruction. Femoral fixation was achieved with a continuous loop Endobutton while tibial fixation was carried out with a Fastlok device augmented by a bone block impacted in the tibial tunnel.

following the procedure. This finding was consistent with the subjective IKDC scores in which an average rating of 80% was obtained. Six months following the procedure, 10% of patients had noted pain over the tibial hardware with associated hypoesthesia over the surgical incision. Clinical examination at final evaluation demonstrated 90 patients with less than 1 cm difference in thigh circumference, two patients with extension lag of 6 degrees, and another two patients with flexion loss of 10 degrees. Kneeling test was positive only in 7% of these patients, while the postoperative Lachman test was negative in 90% (þ1 in nine cases and þ2 in one case). Sensory changes were evident in 30% of patients at 3 months with only 10% having localized hypoesthesia at the proximal third of the tibia at final evaluation. Subsequent radiographs and magnetic resonance imaging (MRI) revealed that only three tibial tunnels and four femoral tunnels were widened more than 25% from the original diameter. However, all these cases retained an anterior laxity that was less than 3 mm and subjectively rated their knees above 80%. MRI studies using T1- and T2-weighted transaxial sequences in 30 patients at 3 and 6 months demonstrated graft incorporation in the tunnels with evidence of viability. Computerized analysis of knee laxity at final followup showed 90 cases to have a side-to-side difference of less than 3 mm, nine cases with 3 to 5 mm of difference, and one case with more than 5 mm of difference. The mean side-toside difference was 1.9 mm (1.7 mm in males and 2.3 mm in females).

16

Isokinetic tests were not significantly different between 6 and 12 months (P ¼ 0.6526). The hamstring/quadriceps ratio was slightly lower in the operated limbs compared with the normal limbs at all test intervals and speed settings but was not statistically significant (P ¼ 0.9576). Neither external (P ¼ 0.6181) nor internal rotation strength (P ¼ 0.3681) demonstrated significant deficits at 6 and 12 months postreconstruction when compared with the normal limb. Knee evaluation scores demonstrated the following: IKDC (A, 66%; B, 24%; C, 9%; D, 1%); Noyes, 87.9 (range 65–100); Lysholm, 93 (range 70–100); and preinjury and postoperative Tegner, 6.1 and 6.0, respectively.

Complications A few patients noted pain on incidental contact at the tibial side, which eventually required removal of the Fastlok device. In five cases, on second-look arthroscopy the grafts remained viable and functional. In addition, two cases had transient superficial wound infection that resolved with antibiotic treatment. In one case, a deep streptococcal infection was documented, which required arthroscopic lavage and débridement. Further evaluation demonstrated chondral damage with loss of motion.

CONCLUSION The technique of using a quadrupled bone-semitendinosus graft construct for ACL reconstruction has results comparable to other techniques in terms of restoration of knee stability, recovery of normal limb strength, and patient satisfaction. This technique effectively combines the biological principles of healing with bone-to-bone contact and high cross-sectional graft area. It provides a viable alternative to other graft types, particularly in patients with preexisting patellar or extensor apparatus problems.

References 1. Gobbi A, Zanazzo M, Tuy B, et al. Patellar tendon versus quadrupled bone semitendinosus ACL reconstruction: a prospective investigation in athletes. Arthroscopy 2003;19:592–601. 2. Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon autograft for anterior cruciate ligament reconstruction: a randomized study with two year follow-up. Am J Sports Med 2001;29:722–728. 3. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146. 4. Shelbourne KD. Donor site problems after anterior cruciate ligament reconstruction using the patellar tendon graft. J Sports Traumatol Rel Res 1995;17:120–128. 5. Pinczewski LA, Clingeleffer AJ, Otto BD, et al. Case report: integration of hamstring tendon graft with bone in reconstruction of the anterior cruciate ligament. Arthroscopy 1997;13:641–643.

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Anterior Cruciate Ligament Reconstruction 6. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5 year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 7. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 8. Maeda A, Shino K, Horibe S. Anterior cruciate ligament reconstruction with multi stranded autogenous semitendonosus tendon. Am J Sports Med 1996;24:504–509. 9. Brown CH Jr, Sklar JH. Endoscopic anterior cruciate ligament reconstruction using quadrupled hamstring tendons and Endobutton femoral fixation. Tech Orthop 1998;13:281–298. 10. Weiler A, Scheffler S, Gockenjau A, et al. Different hamstring tendon graft fixation techniques under incremental loading conditions (abstract). Arthroscopy 1998;14:425–426.

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11. Morgan C. The bone-hamstring-bone composite autograft for ACL reconstruction. Presented at the AAOS, New Orleans, Month, 1994. 12. Gobbi A, Panuncialman I. Quadrupled bone-semitendinosus ACL reconstruction: a prospective clinical investigation in 100 patients. J Orthopaed Traumatol 2003;3:120–125. 13. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 14. Rosenberg TD, Pazik JT. Anterior cruciate ligament reconstruction with quadrupled semitendinosus autograft. In Parisen JS (ed). Current techniques in arthroscopy. Current medicine. Philadelphia, 1996, Churchill Livingstone, pp 77–78.

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use INTRODUCTION Use of the four-strand hamstring (4HS) graft using the semitendinosus (ST) with or without the gracilis (Gr) has increased dramatically in the past 5 years. This graft has long been considered to have lower morbidity than bone–patellar tendon–bone (BPTB) grafts. After reports showed its clinical stability results to meet or exceed those of the BPTB,1–7 its use began to significantly increase. 2ST/2Gr is the most commonly used hamstring graft, followed by 4ST. However, a total of six different multistrand hamstring graft configurations have been reported and are in current use. This chapter will describe the advantages of each configuration according to the five parameters involved in decision making. Graft preparation techniques will also be described.

THE PARAMETERS FOR CHOOSING A HAMSTRING GRAFT CONFIGURATION Five parameters (Table 17-1 and see later discussion) will drive decision making regarding which HS graft, or soft tissue graft in general, will be used. The first three parameters are available graft length in the tunnel, the type of fixation that can be used, and whether the gracilis must be sacrificed. These are generally themost important considerations to most orthopaedic surgeons. The last two parameters, relative graft strengths and whether it is double-bundle compatible, are important to some.

1. Is the Graft Long Enough to Allow Adequate Tunnel Healing?

17 CHAPTER

Chadwick C. Prodromos

In our experience, ST harvests range in length from 24 to 34 cm, with most being between 26 and 30 cm in usable length. Intraarticular anterior cruciate ligament (ACL) length is 3 to 3.5 cm.8 Roughly 1 cm of shortening occurs as a result of whipstitch implantation. Thus, for example, a 27-cm graft will be 26 cm after suturing. When quadrupled, this length is 6.5 cm. Subtracting 3 cm for the intraarticular portion leaves 3.5 cm of graft for both tunnels, or about 1.75 cm or 17.5 mm for each tunnel. If the ST is only doubled and not quadrupled, the resultant 12 cm or longer graft can provide 4 cm or more of graft length in each tunnel. Some surgeons9 will use 4ST if the ST is 30 cm or longer and 2ST/2Gr if the ST harvest is less than 30 cm.

The Argument for Greater Length Being Necessary Many surgeons are not comfortable with graft lengths of less than 2 cm in each tunnel. The principal argument in favor of this is the study by Greis et al10 that shows greater pull-out strength as graft length increases.

The Argument for Less Length Being Sufficient However, there is a significant body of data indicating that 15 mm or even less graft in a tunnel is acceptable. A recent study by Zantop et al in goats using Endobutton fixation showed 115

Anterior Cruciate Ligament Reconstruction TABLE 17-1 Advantages and Disadvantages of Various Graft Configurations Strength

Sacrifice Gracilis

Interference Screw Compatible

Graft Length in Tunnel

Two-Bundle Compatible

2ST/2Gr

High

Yes

Yes

Long

No

3ST

Moderate

No

No

Medium

No

3ST/2Gr

High

Yes

No

Medium

Yes

3ST/3Gr

High

Yes

No

Medium

Yes

4ST

High

No

No

Short

Yes (?)

4ST/4Gr

High

Yes

No

Short

Yes

Gr, Gracilis; ST, semitendinosus.

no difference in load to failure between 15 mm and 25 mm of graft in the tunnel.11 A study by Yamazaki et al in dogs using whipstitch cortical screw post fixation showed no difference between 5 mm and 15 mm.12 Equally persuasive in favor of shorter lengths being acceptable is the clinical experience of a number of experienced surgeons such as Rosenberg and Cooley2 and Paulos13 who have had excellent results using 15-mm grafts. We have also used 15 mm as a minimum without a graft failure.

2. Is the Graft Long Enough to Allow Direct Tibial Fixation or Only Indirect? Direct fixation includes all interference screw and interference screw–based techniques such as Intrafix and techniques that rely on direct friction with the graft, such as the WasherLoc. Indirect fixation uses a fabric interface with the graft such as the whipstitch post technique or Fastlok. As seen in Table 17-1, use of the Gr as well as the ST is necessary to be certain of a long-enough graft to ensure the use of direct fixation techniques.

3. Is the Gracilis Sacrificed? The Gracilis Is not Really a Hamstring One argument against the 2ST/2Gr graft is that it disables not one but two hamstring muscles because the Gr is also harvested in addition to the ST. However, the Gr is not really a hamstring. Gray’s Anatomy14 lists only three hamstring muscles: the biceps femoris, semimembranosus, and ST. All are innervated by the sciatic nerve; all flex the knee. The Gr is not listed as a hamstring. Rather, the Gr is listed with the adductors longus, brevis, and magnus as “medial femoral muscles.” All of these muscles, including the Gr, are innervated by the obturator nerve. The gracilis’ action is listed as “adducts the thigh.” Thus, the loss of the Gr is not the loss of a second hamstring. Rather, it is 116

the loss of an accessory adductor, much as the loss of the ST is the loss of an accessory hamstring.

What Is Lost by Harvesting the Gracilis in Addition to the Semitendinosus? Chapter 67 reviews strength after hamstring harvest. Hamstring strength can be restored in virtually 100% of patients in our experience. Specific testing has noted a small decrease in peak flexion torque at high flexion angles and decreased tibial internal rotation strength in flexion; however, no clinical deficit has ever been reported in function as a result of the addition of Gr harvest relative to ST alone. On theoretical grounds, some have avoided Gr harvest in sprinters and soccer players.15 However, performance deficits or subjective complaints have not been reported in this group. Anecdotally, we have performed bilateral 2ST/2Gr in a professional soccer player with excellent subsequent performance.

4. How Strong Is the Graft? Using the data from the classic study of Noyes et al16 in which the ST was 70% of the strength of the native ACL and the Gr was 49% of the strength, extrapolated hamstring graft strengths can be estimated. The 4ST would be 280%, the 2ST/2Gr would be 238%, the 3ST would be 210%, and the 2ST would be 140%. The 4ST and 2ST/ 2Gr have produced very high stability rates in clinical series.2–7 The 2ST has been associated with low rates, although this may well be largely due to the outmoded fixation that was used when those studies were done.17–19 Regardless of whether this is true, few surgeons today are comfortable with only a 2ST graft. The 3ST graft has produced high stability in some20 but not all21 series. This mixed clinical performance and the lower strength of the graft coupled with the increased complexity of using an odd-stranded graft in the femur has resulted in this graft being seldom used.

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use

5. Is the Graft Double-Bundle Compatible? Yasuda et al22 have reported a six-strand, double-bundle technique with 3ST/3Gr, as described in Chapter 22. Christel uses a 2ST anteromedial (AM) bundle and either a 2Gr or 3Gr (if the Gr is small) posterolateral (PL) bundle, as described in Chapter 23. Zhao et al have reported a 4ST AM and 4Gr PL bundle eight-strand technique.23 Generally, excellent stability has been reported with these techniques. As with the later-described 5HS single-bundle technique, 6HS and 8HS techniques have not seemed to have the problems associated with the large size of these grafts, which are significantly larger than the native ACL. 2ST/2Gr has generally not been used in a double-bundle configuration. Single-bundle techniques use primarily AM bundle positioning. This has produced high success rates. The argument for double-bundle techniques supposes that the addition of a PL bundle can only help stability. However, PL bundle techniques are new and questionable to many. If the AM bundle is significantly weakened to provide a graft for the PL bundle, then the entire graft may be too weak if the PL technique is indeed not providing significant additional strength. Taking the Gr away from the AM bundle would leave only a 2ST graft, which alone has performed poorly in the literature in the past. It would seem safer to leave a stronger AM bundle, at least a 3ST graft, which would then be augmented by the PL bundle. Gobbi has reported excellent success with a 2ST AM bundle, but he has used the stronger 2ST graft rather than 2Gr for a PL bundle (see Chapter 24).

GRAFT PREPARATION TECHNIQUES 2ST/2Gr Graft Preparation Technique Using Endobutton Femoral and Whipstitch Posttibial Fixation

A sizer is slipped down the over the loop of the quadrupled graft for a distance of about 3 cm to ascertain the size of this femoral end separately from the tibial. We then add 0.5 to 1 mm of size to the tibial measurement to account for the greater bulk that will result from the second whipstitch when it is put into the paired proximal ends of the tendons after their length is determined. The tibial and femoral tunnels are then drilled using these tendon girth measurements.

Calculating the Optimal Length for the Graft If sufficient length exists, we will try to obtain 2.5 to 3 cm of graft in the femoral socket but will accept as little as 15 mm as described. Approximately 3.5 cm of intraarticular length and 3 cm of tibial length are then added to the calculation so that the usual graft will be about 9.5 cm in length. The graft is then cut to the necessary length. In this example the graft would be cut at 20 cm in length because 0.5 cm of shortening usually occurs between the insertion of the second whipstitch and the folding of the graft in the Endobutton. Thus, this 20-cm graft when doubled will be 10 cm in theory but closer to 9.5 cm in practice. However, if the femoral tunnel is shorter we will make the graft correspondingly shorter as well. In this example, if the femoral socket were 1.5 cm we would add 3.5 cm intraarticular and 3 cm tibial for a length of 8 cm. In theory this would require a 16-mm graft, but again we would add 1 cm to make it 17 mm in length. We restrict the graft length so that the graft will not have excessive length and abut the cortical screw post we use, resulting in an inability to create tension in the graft. In making these calculations, one can always assume the tibial tunnel to be at least 3 cm in length, and usually it is 4 to 5 cm in length. If any question exists in the surgeon’s mind, the intraarticular length and tibial tunnel length can be easily directly measured using the longdepth gauge in the Endobutton system or by other means.

Cleaning and First Whipstitch Implantation

Second Whipstitch Implantation and Trimming

After harvest the tendons should be cleaned of muscle tissue. We place whipstitches (see Chapter 42) in the combined tibial attachment of #5 braided nonabsorbable or #2 braided high-strength nonabsorbable suture such as Fiberwire (Arthrex, Naples, FL) or ultra-braid (Smith & Nephew, Andover, MA). We do not cut the graft at this point and do not whipstitch the other end. It is better to determine length once tunnel lengths have been determined.

Once the appropriate length has been determined, the two free proximal ends of the graft are doubled and a hemostat is clamped just beyond the desired length. The extra graft is cut off with a 15 blade scalpel, with the hemostat left in place on the doubled ends of the graft. The other whipstitch is then woven into the graft. The hemostat is removed after the second suture pass. Excess graft is carefully then trimmed from both ends. Removing “dog ears” will facilitate smooth graft passage. A snug fit is desirable, but do not try for too tight a fit or the graft will be traumatized during passage or may not pass at all. The graft is now ready for passage and fixation.

Sizing the Graft The graft is then sized. Usually the femoral end where the graft is looped will be about 1 mm thinner than the tibial end.

17

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Anterior Cruciate Ligament Reconstruction

TROUBLESHOOTING What if Either the ST or Gr Is Cut Too Short to Double? We have not had this occur using the posterior mini-incision harvest technique (see Chapter 13). However, if graft length is questionable, the first step should be to precisely measure the intraarticular length. The minimum graft we have used is this length plus 15 mm for each of the tibial and femoral tunnels. Thus, a 30-mm intraarticular length would allow a 30 þ 15 þ 15 ¼ 60 mm total graft. Six centimeters doubled is 12 cm. Adding 1 cm for shortening yields a 13-cm graft. Thus, all that should be necessary for most knees for a 4ST/Gr graft is a total length of 13 cm or 14 cm, allowing for measurement error. If the surgeon has this length, then he or she should be fine to proceed. If either the ST or Gr is shorter than this length, then the surgeon should plan to triple the other tendon to add to the single short limb of the short tendon. The two possibilities would thus be either 3ST/1Gr (stronger than 2ST/2Gr) or 1 ST/3Gr (not as strong as 2ST/2Gr but more than sufficiently strong). We would then implant whipstitches in the free ends. Whipstitch post fixation or Endobutton could then be used for femoral fixation. Cross-pin fixation would generally be difficult without the ability to loop each graft.

What if the Graft Is Too Big to Pass? The easiest first step is to trim the graft at the edges or elsewhere and try again. If it still will not pass, then the tunnel or tunnels must be enlarged slightly.

FIVE STRAND USING 3ST/2Gr Surgical Technique The ST and Gr are harvested in the usual fashion. The ST is measured and, provided that it is at least 22.5 cm in length, the proximal one-third is sectioned from the distal two-thirds. For example, a 24-cm ST would be cut to leave 16 cm intact with its insertion, and the proximal 8 cm would be cut off to use as a single limb. This tissue would otherwise be discarded. In our experience the ST is always at least 24 cm in length, and no more than 15 cm is ever required for 2ST/2Gr. Thus, there is almost always a third (if not a fourth) limb of ST that would otherwise be discarded. Number 2 whipstitches are placed in each end of this extra graft limb. The whipstitches from one end are tied one to one around the fabric loop of the Endobutton loop (Fig. 17-1). The sutures from the other end are tied one to one around the tibial cortical screw. 118

FIG. 17-1 The fifth limb of the graft is shown as elevated above the remaining 2ST/2Gr graft. Whipstitches are tied around the Endobutton loop.

Results We recently presented an 8- to 9-year follow-up of a fivestrand technique using whipstitch post fixation on both the tibia and femur24 in 20 consecutive patients. This was the first report of a greater than four-strand HS graft using a single-bundle technique. No graft failures were found, and 89% of the grafts were within 1 mm of the opposite knee. The mean side-to-side KT-1000 difference of 0.44 mm is the lowest reported for an ST/Gr graft. We compared this group with a previously reported high-stability 2ST/2Gr cohort and found significantly higher stability with the five-strand graft.

Morbidity All patients regained full motion. There were no symptoms attributable to the greater size of the graft. Thus, we believe that this larger graft can safely be used without concerns for impingement if tunnels are properly placed.

Uses This technique is useful in patients with ligamentous laxity, small tendons, or other stability risk factors for which the strongest possible graft is required. It is also of use in double-bundle techniques. The 3ST part of the graft allows the AM bundle to approximate the strength of a 2ST/2Gr single bundle (210% versus 238% of the approximate strength of the native ACL by extrapolation from the data of Noyes25). Thus, the use of the Gr for the PL bundle does not need to significantly weaken the AM bundle, which closely corresponds to what most surgeons were using for a single bundle. This provides a measure of insurance in case the more difficult PL bundle is misplaced or inadequately

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use tightened. Because double-bundle techniques are new to most surgeons, this should essentially eliminate any “learning curve” laxity as facility with the double-technique is gained and as further research shows the best ways to perform the double-bundle procedure.

FOUR-STRAND ST GRAFT PREPARATION TECHNIQUE 4ST with Bone Block See Chapter 16 for a description of this technique.

4ST Free Graft Without Bone Block This technique is similar to the 2ST/2Gr described previously. The two free ends of the graft are overlapped, and a whipstitch of #5 braided nonabsorbable suture is placed. Another whipstitch is then put into the apex of the graft as it is held taut with a #5 or #2 suture placed within the fold of the tendon while strong tension is exerted on the opposite free ends. The net result is a double-thickness graft, which can be fixated in an identical manner as the 2ST/2Gr graft.

CONCLUSIONS 1 There are five parameters for choosing a hamstring graft configuration: length for tunnel healing, length for fixation compatibility, whether or not the Gr is sacrificed, strength, and double-bundle compatibility. 2 2ST/2Gr is preferred to 4ST by most surgeons due to the greater available graft length. Some surgeons will use 4ST with 30 cm or longer ST harvests and 2ST/2Gr with shorter harvests. 3 4ST offers the advantage of not harvesting the Gr. 4 The 3ST/2Gr five-strand graft offers very high strength and more length than the 4ST. It is useful in patients with ligamentous laxity, small tendons, or other stability risk factors. 5 Regarding minimum graft tunnel length: 15 mm of graft would appear to be all that is necessary in the tunnels for adequate healing. Overly aggressive rehabilitation in the first 8 weeks should be avoided. 6 Gracilis harvest does not disable two hamstrings because the Gr is not a hamstring but rather is an adductor, both anatomically and functionally. It deactivates one accessory hamstring and one accessory adductor. In both cases,

17

function is well taken up by the prime movers in each group.

References 1. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 2. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 3. Gobbi A, Tuy B, Mahajan S, et al. Quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a clinical investigation in a group of athletes. Arthroscopy 2003;19:691–699. 4. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 5. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 6. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20: 1015–1025. 7. Gobbi A, Mahajan S, Zanazzo M, et al. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation in athletes. Arthroscopy 2003;19:592–601. 8. Duthon VB, Barea C, Abrassart S, et al. Anatomy of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14: 204–213. 9. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at the 2006 Symposium of the American Academy of Orthopaedic Surgeons, AAOS Symposium—Controversies in Soft Tissue Reconstruction, Chicago, March, 2006. 10. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex: a biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 11. Zantop T, Brucker P, Bell K, et al. The effect of tunnel-graft length on the primary and secondary stability in ACL reconstruction: a study in a goat model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 12. Yamazaki S, Yasuda K, Tomita F, et al. The effect of intraosseous graft length on tendon-bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 2006;14:1086–1093. 13. Paulos L. Personal communication, May 2006. 14. Goss CM. Muscles and Fasciae. In Gray's anatomy, ed 29. Philadelphia, Lea and Febiger, Courage Books, 1973, pp 495–503. 15. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 16. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg Am 1984;66A:344–352. 17. Meyestre J, Vallotton J, Benvenuti J. Double semitendinosus anterior cruciate ligament reconstruction: 10-year results. Knee Surg Sports Traumatol Arthrosc 1998;6:76–81. 18. Aglietti P, Buzzi R, Menchetti P, et al. Arthroscopically assisted semitendinosus and gracilis tendon graft in reconstruction for acute

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19.

20.

21.

22.

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anterior cruciate ligament injuries in athletes. Am J Sports Med 1996;24:726–731. Anderson A, Snyder R, Lipscomb B. Anterior cruciate ligament reconstruction: a prospective randomized study of three surgical methods. Am J Sports Med 2001;29:272–279. Goradia VK, Grana WA. A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts. Arthroscopy 2001;17:383–392. Harilainen A, Sandelin J, Jansson KA. Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33. Yasuda K, Kondo E, Ichiyama H, et al. Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction

procedure using hamstring tendon grafts: comparisons among three different procedures. Arthroscopy 2006;22:240–251. 23. Zhao J, Peng X, He Y, et al. Two-bundle anterior cruciate ligament reconstruction with eight-stranded hamstring tendons: four-tunnel technique. Knee 2006;13:36–41. 24. Prodromos CC, Joyce BT. Five-strand hamstring ACL reconstruction: a new technique with better long-term stability than four-strand. Presented at the 2006 meeting of the Arthroscopy Association of North America Hollywood, FL, May, 2006. 25. Noyes FR, Butler DL, Grood ES, Zernicke RF, Hefzy MS. Biomechanical analysis of human ligament grafts used in kneeligament repairs and reconstructions. J Bone Joint Surg Am 1984;66-A:344–352.

PART D PRINCIPLES OF TUNNEL FORMATION SUB PART I SINGLE FEMORAL-TUNNEL FORMATION

Use of the Transtibial Technique to Avoid Posterior Cruciate Ligament and Roof Impingement of an Anterior Cruciate Ligament Graft INTRODUCTION This chapter discusses the definition, complications, diagnosis, and prevention of posterior cruciate ligament (PCL) and roof impingement, which must be avoided to restore motion and stability in an anterior cruciate ligament (ACL) reconstructed knee. Evidence will be presented that the key tunnel in the transtibial technique is the tibial tunnel. Correct placement of the tibial tunnel in the coronal and sagittal planes, and subsequent drilling of the femoral tunnel through the tibial tunnel, avoids PCL and roof impingement, replicates the tension pattern of the intact ACL, and determines the motion and stability of the knee. The rationale for preventing PCL and roof impingement requires an understanding of the anatomy of the intercondylar notch, especially the wide variations in the cross-sectional relationship between the ACL graft, intact ACL, and PCL. A time-tested and scientifically evaluated surgical technique for placing the tibial and femoral tunnels that consistently prevents PCL and roof impingement is presented. This simple and accurate technique relies on widening the notch by performing a wallplasty and using a tibial guide that controls the angle of the tibial tunnel in the coronal plane and registers the intercondylar roof with the knee in extension in the sagittal plane. In the coronal plane, the tibial guide prevents PCL impingement by customizing the placement of the guidewire at 60 to 65 degrees with

respect to the medial joint line of the tibia and placing the lateral edge of the tibial tunnel through the tip of the lateral tibial spine. In the sagittal plane, the tibial guide prevents roof impingement by placing the guidewire 5 to 6 mm posterior and parallel to the intercondylar roof with the knee in maximal hyperextension.

18 CHAPTER

Stephen M. Howell

DEFINITION, COMPLICATIONS, AND DIAGNOSIS OF POSTERIOR CRUCIATE LIGAMENT IMPINGEMENT PCL impingement occurs when the ACL graft wraps around the PCL as the knee is flexed. Impingement of the ACL graft around the PCL causes a tension rise in flexion that either limits flexion or stretches the ACL graft, resulting in anterior instability. Not widening the notch and malplacement of the ACL graft in the coronal plane cause PCL impingement in the transtibial technique.1–3 PCL impingement can be suspected if bone was not removed from the lateral femoral condyle (i.e., a wallplasty) until the space between the PCL and lateral femoral condyle exceeded the width of the ACL graft by 1 mm. An anteroposterior (AP) radiograph is diagnostic of PCL impingement when the tibial tunnel is at an angle greater than 70 degrees with respect to the medial joint line or when the lateral edge of the tibial tunnel is medial to the apex of the lateral tibial spine2 (Fig. 18-1). Magnetic resonance imaging (MRI) with three-dimensional (3D)

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FIG. 18-1 The anterior cruciate ligament (ACL) grafts in both of these knees suffered from posterior cruciate ligament (PCL) impingement. The surgical error in the left radiograph was that the tibial tunnel was placed too vertical at 85 degrees, which placed the femoral tunnel at the apex of the notch. The tibial tunnel should have been placed at 65 degrees with respect to the medial joint line of the tibia. However, placing the tibial tunnel at 65 degrees does not guarantee that the ACL graft is placed without PCL impingement. The surgical error in the right radiograph is that the notch was not widened with a wallplasty, and the tibial tunnel and femoral tunnel were placed too medial, such that the femoral tunnel was at the apex of the notch. The lateral edge of the tibial tunnel should pass through the tip of the lateral spine, not through the tip of the medial spine.

reconstruction is diagnostic of PCL impingement when there is no space between the ACL graft and PCL or when the ACL graft does not run straight and is deformed by the PCL.1 Arthroscopy is diagnostic of PCL impingement when there is no space between the ACL graft and PCL at the apex of the notch and when the ACL graft is slack and bows laterally with the knee in 30 degrees of flexion.3 Surgeons who avoid PCL impingement will find that their patients have better knee flexion and better anterior and rotatory stability.1,2

DEFINITION, COMPLICATIONS, AND DIAGNOSIS OF ROOF IMPINGEMENT Roof impingement occurs when the intercondylar roof contacts the ACL graft before the knee reaches full extension. Impingement of the ACL graft against the intercondylar roof causes either a loss of extension or a stretching out of the graft from abrasion, resulting in anterior instability. The cause of roof impingement is malplacement of the ACL graft in the sagittal plane. Placing the tibial tunnel anterior to the intercondylar roof with the knee in maximal extension causes roof impingement.4–7 122

A lateral radiograph of the knee in maximal extension is diagnostic of roof impingement when the tibial tunnel is anterior to the intercondylar roof (Fig. 18-2). The lateral radiograph is less helpful in evaluating a bone–patellar tendon–bone graft than a soft tissue graft because the bone plug may obscure the wall and orientation of the tibial tunnel and because the tendon does not fill the bone tunnel.7 An MRI is diagnostic of roof impingement when the pathognomonic regionalized signal increase occurs in the graft, which is confined to the distal two-thirds of the ligament within the intercondylar notch. The portion of the ACL graft in the tibial and femoral tunnel and the portion of the graft that exits the femoral tunnel retain a low signal, which is identical to the PCL and patellar tendon.8–10 Arthroscopy is diagnostic of roof impingement when the ACL graft is frayed or a fibrous nodule is formed at the entrance of the tibial tunnel into the notch.11 Surgeons who avoid roof impingement will find that their patients have better knee extension and stability.7,12

THE TIBIAL TUNNEL: THE KEY TUNNEL IN THE TRANSTIBIAL TECHNIQUE The advantage of the transtibial technique is that when the notch is widened and the tibial tunnel is placed correctly in

Use of the Transtibial Technique to Avoid Posterior Cruciate Ligament and Roof Impingement of an Anterior Cruciate Ligament Graft

18

FIG. 18-2 The bone–patella–bone graft failed from roof impingement (left radiograph). The surgical error was that the tibial tunnel was placed anterior to the intercondylar roof with the knee in full extension. The graft failed due to abrasion and stretch-out. The tibial tunnel was moved more posterior in the revision with a hamstring anterior cruciate ligament (ACL) graft (right radiograph). The hamstring graft was pushed more posterior by a bone graft placed along the anterior edge of the tunnel (asterisk). The tibial tunnel should be placed posterior to the intercondylar roof with the knee in maximal extension.

the coronal and sagittal plane, the correct placement of the femoral tunnel is automatic. The reason for this is that the position of the over-the-top femoral aimer and the position of the reamer are both controlled by the tibial tunnel.3 If the notch is not widened and the tibial tunnel is placed incorrectly in either the coronal or sagittal plane, then the femoral tunnel will be placed incorrectly and the patient will suffer from motion loss or instability.1,2,7 The feasibility of the transtibial technique to replicate the tension pattern of the intact ACL was determined by a cadaveric study that analyzed the effect of varying the angle of the tibial tunnel (and femoral tunnel) in the coronal plane on the tension pattern of the ACL graft (Fig. 18-3). Drilling the tibial tunnel at an angle of 60 degrees in the coronal plane placed the ACL graft far down the side wall of the notch away from the PCL, and the tension in the graft matched the intact ACL. Drilling the tibial tunnel at 70 and 80 degrees placed the ACL graft near the apex of the notch and the PCL, and the tension increase in the ACL graft with knee flexion was subsequently abolished by incremental excision of 2 to 6 mm of the lateral edge of the PCL. Therefore, the cause of the abnormal tension rise in flexion is the premature mechanical impingement of the ACL graft on the PCL during flexion and is avoided by placing the tibial tunnel at an angle less than 70 degrees.3

RATIONALE FOR WIDENING THE NOTCH TO PREVENT POSTERIOR CRUCIATE LIGAMENT IMPINGEMENT The surgeon must recognize that a soft tissue ACL graft is bigger than the intact ACL. Women of the same height and weight as men have significantly narrower notches, which means that women require more of a wallplasty than males for the same-diameter graft.13 An MRI study of the cross-section of the intercondylar notch has shown that the intact ACL is thin and elongated and fits snugly between the lateral edge of the PCL and the medial edge of the lateral femoral condyle.1 The use of a soft tissue ACL graft that is rounder and larger in a cross-sectional area than the intact ACL requires widening the notch until the space between the lateral femoral condyle and PCL exceeds the width of the graft by 1 mm. Arthroscopy has shown that the portion of the notch occupied by the PCL and intact ACL varies widely. Most notches are “PCL dominant,” in which the PCL occupies a larger crosssectional area than the ACL (Fig. 18-4). Because surgeons prefer an ACL graft with a diameter of 8 to 10 mm, a wallplasty is required to make room for the larger ACL graft in almost every ACL reconstruction, especially in females. 123

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FIG. 18-3 The key tunnel in the transtibial technique is the tibial tunnel because the position of the over-the-top femoral aimer and the position of the reamer are both controlled by the tibial tunnel. When the tibial tunnel is drilled at 60 degrees with respect to the medial joint line, the femoral tunnel is placed farther down the side wall away from the posterior cruciate ligament (PCL), and the tension pattern in the graft is the same as the intact anterior cruciate ligament (ACL). When the tibial tunnel is drilled at 80 degrees, the femoral tunnel is placed near the apex of the notch adjacent to the PCL, and the tension pattern in the graft is abnormally increased at 60 degrees of knee flexion. The tension increase in flexion is caused by the graft impinging against the PCL, which either limits knee flexion or causes the graft to stretch, resulting in increased anterior laxity.

PRINCIPLE FOR AVOIDING POSTERIOR CRUCIATE LIGAMENT AND ROOF IMPINGEMENT The principle for avoiding PCL and roof impingement is to widen the notch and correctly place the tibial tunnel in the coronal and sagittal planes (Fig. 18-5). In the coronal plane, the angle of the tibial tunnel should be 60 to 65 degrees with respect to the medial joint line of the tibia, and the lateral edge of the tibial tunnel should pass through the tip of the

lateral spine.3 In the sagittal plane, the position of the tibial tunnel should be posterior and parallel to the intercondylar roof with the knee in extension, and the position should be customized based on variability in knee extension and roof angle so that a roofplasty is not required.6,14,15 Customized placement of the tibial tunnel in the sagittal plane is necessary because the sagittal depth of the insertion of the ACL is variable, the roof angle varies from 23 to 60 degrees, and knee extension varies from 5 to 15 degrees

FIG. 18-4 Notches come in many sizes and shapes; however, most notches are too narrow to hold an 8- to 10-mm round soft tissue anterior cruciate ligament (ACL) graft. The normal ACL is thin, spindle shaped, and much narrower than the cross-section of an 8- to 10-mm graft. Furthermore, the notch in females is narrower than in males, and many notches in both genders are posterior cruciate ligament (PCL) dominant, with more than half of the cross-section of the notch occupied by the PCL (left). Performing a wallplasty until the width between the lateral edge of the PCL and the lateral femoral condyle exceeds the width of the graft by 1 mm helps prevent PCL impingement. Widening the notch allows the tibial tunnel to be placed more lateral so that the lateral edge of the tibial tunnel passes through the tip of the lateral spine.

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Use of the Transtibial Technique to Avoid Posterior Cruciate Ligament and Roof Impingement of an Anterior Cruciate Ligament Graft

18

FIG. 18-5 The optimal placement for the tibial tunnel in the coronal and sagittal planes is shown. The lateral edge of the tibial tunnel passes through the tip of the lateral tibial spine (asterisk), and the tibial tunnel forms an angle between 60 and 65 degrees with respect to the medial joint line in the coronal view (left). The tibial tunnel is posterior to the intercondylar roof with the knee in extension (right). This patient regained full flexion and extension and remained stable because the anterior cruciate ligament (ACL) graft was placed without posterior cruciate ligament (PCL) and roof impingement.

of hyperextension.14 The variability in the sagittal depth of the ACL insertion from 11 to 30 mm makes it a poor landmark for a point-and-shoot guide to select the position for an ACL graft with a diameter of 8, 9, or 10 mm.6 Customizing the placement of the tibial tunnel in the sagittal plane requires a tibial guide that registers the intercondylar roof with the knee in maximal hyperextension.16,17 The advantage of customizing the tibial tunnel is that roof impingement is avoided without a roofplasty, which has been shown to increase the graft tension at midrange of flexion and increase anterior laxity as the knee is flexed.15

SURGICAL TECHNIQUE FOR AVOIDING POSTERIOR CRUCIATE LIGAMENT AND ROOF IMPINGEMENT AND REPLICATING THE TENSION PATTERN OF THE INTACT ANTERIOR CRUCIATE LIGAMENT This surgical technique requires the use of a tibial guide that registers the intercondylar roof and a coronal alignment rod placed in the handle of the guide that allows the angle of the tibial tunnel in the coronal plane to be visually adjusted by the surgeon at the time of reconstruction (Howell 65 , Howell Tibial Guide, Arthrotek, Warsaw, IN)18 (Fig. 18-6). The use of a coronal alignment guide reduces the need for inoperative radiography to check the positioning of the tibial tunnel.

The initial arthroscopic examination of the notch should focus on removing the remnant of the torn ACL and clearly visualizing the lateral edge of the PCL. The tip of the guide, which is 9.5 mm wide, is passed between the PCL and the lateral femoral condyle. The knee is then gradually extended to examine whether enough space exists between the lateral femoral condyle and the PCL. The notch is then widened from its base to the apex until the 9.5-mm-wide tip of the guide easily passes between the lateral femoral condyle and the PCL (Fig. 18-7). A roofplasty is not performed. The tibial guide is then reinserted, and the knee is placed in full hyperextension (see Fig. 18-6). The heel of the patient’s leg is placed on the Mayo stand to maintain the knee in maximal hyperextension. The coronal alignment guide is inserted into the guide, the knee is brought into full hyperextension so that it is parallel to the roof, and the coronal alignment rod is adjusted so that it is parallel to the joint line and perpendicular to the tibia. The guidewire is drilled through the lateral hole in the bullet, which moves the guidewire laterally away from the PCL. The position of the guidewire is then checked arthroscopically. In the AP view the guidewire should enter midway between the lateral edge of the PCL and lateral femoral condyle. In full extension a probe can be placed between the anterior surface of the guidewire and the roof, and there should be 2 to 3 mm of clearance, which indicates that the guidewire is not placed too far posterior. 125

Anterior Cruciate Ligament Reconstruction

a

a

FIG. 18-6 The 65-degree Howell Tibial Guide simultaneously orients the tibial tunnel in both the sagittal and coronal planes. The guide is inserted into the notch, the knee is maximally extended, and the surgeon lifts the handle of the guide, which aligns the guidewire 6 mm posterior and parallel to the intercondylar roof. An alignment rod (a) is inserted into the handle of the guide, and the guide is rotated until the rod is parallel to the joint line and perpendicular to the long axis of the tibia, which sets the angle of the tibial tunnel in the coronal plane at 65 degrees. The guidewire is drilled through the lateral rather than the central hole in the bullet, which moves the tibial tunnel away from the lateral edge of the posterior cruciate ligament (PCL).

After drilling the tibial tunnel, an impingement rod is passed into the knee through the tibial tunnel with the knee in maximal hyperextension. Free passage of the impingement rod into the notch indicates no impingement of the ACL graft against the PCL, lateral femoral condyle, and intercondylar roof. A size-specific femoral aimer with an offset that produces a femoral tunnel with a 1-mm back wall is then inserted through the tibial tunnel. The tip of the femoral aimer is hooked proximal to the lateral wall of the notch and rotated slightly lateral away from the PCL. Once the graft is passed, a triangular space should be seen between the PCL and the ACL graft at the apex of the notch (Fig. 18-8).

VALIDATION OF TIBIAL GUIDE One advantage of drilling the tibial tunnel with the knee in full hyperextension using the 65-degree tibial guide is that no manipulation of the knee is required to reduce the knee and drill the guidewire anatomically. Simply extending the knee and placing the heel on the Mayo stand suspends the knee and allows gravity to reduce the tibia on the femur.17 The 65-degree tibial guide was shown to place the tibial tunnel on the posterior half of the ACL footprint and avoid roof impingement without a roofplasty in a cadaveric study of 21 knees.13 Mapping demonstrated a widevariety in width, depth, and shape of the footprint of the

FIG. 18-7 Most notches are too narrow to accommodate an 8- to 10-mm round soft tissue anterior cruciate ligament (ACL) graft. In this case, the notch is posterior cruciate ligament (PCL) dominant, with more than half of the cross-section of the notch being occupied by the PCL (left). A wallplasty is performed until the space between the PCL and lateral femoral condyle exceeds the width of the graft by 1 mm (center). The adequacy of the wallplasty is confirmed by free passage of the 9.5-mm-wide tip of the tibial guide between the PCL and lateral femoral condyle (right).

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18

FIG. 18-8 These arthroscopic views show what not to do and what to do to correctly place the tibial and femoral tunnel using the transtibial technique. The tibial guidewire should pass midway between the posterior cruciate ligament (PCL) and the lateral femoral condyle and not cross the PCL at the floor of the notch (left). The femoral tunnel ends up too vertical when the guidewire crosses the PCL at the floor of the notch, and there is no triangular space between the anterior cruciate ligament (ACL) graft and PCL at the apex of the notch, which is diagnostic of PCL impingement (center). The correctly placed tibial and femoral tunnel is more lateral to the PCL, and a relatively large triangular space exists at the apex of the notch between the ACL graft and PCL (right).

intact ACL insertion, which emphasizes the difficulty in selecting the location of the tibial tunnel with use of a point-and-shoot guide and using the ACL insertion as a target. The consistency of the relationship of the ACL to the intercondylar roof and the inconsistency of the footprint substantiate the principle of using a tibial guide that registers the intercondylar roof with the knee in full hyperextension to select the position of the tibial guidewire.19 The use of the coronal alignment guide is preferred over the use of a “clock” as a way of judging whether the femoral tunnel is placed correctly in the coronal plane. A simple experiment can be done to show how imprecise the use of the clock is in determining the location of the femoral tunnel in the coronal plane. With the femoral guidewire drilled through the tibial tunnel and into the notch, place the scope through the anterolateral or transpatellar porta, and rotate the 30-degree arthroscope and camera independently. The “time” formed by the guidewire and the margin of the intercondylar notch will vary by 2 hours. Repeat the experiment in the anteromedial portal, and observe how the maximal and minimal time differs from the view in the previous portal. Therefore, one surgeon’s two-o’clock position may be another surgeon’s one-o’clock position, depending on the choice of portal, rotation of the scope, and rotation of the camera.

SUMMARY Proper tunnel placement is essential for a successful ACL reconstruction. The complications that are caused by a poorly placed tibial tunnel in the coronal or sagittal plane cannot be overcome by the best graft material, fixation methods, or rehabilitation program. Correct tibial tunnel placement in the AP plane requires that the notch be

widened so that the space between the PCL and lateral femoral condyle exceeds the diameter of the graft by 1 mm, the tibial tunnel is placed such that the lateral edge passes through the tip of the lateral spine, and the angle formed by the tibial tunnel and the medial joint line and tibia is between 60 and 65 degrees. In the sagittal plane, the center of the tibial tunnel must be aligned 4 to 5 mm posterior to the intercondylar roof in the extended knee so that roof impingement is avoided without performing a roofplasty.

References 1. Fujimoto E, Sumen Y, Deie M, et al: Anterior cruciate ligament graft impingement against the posterior cruciate ligament: diagnosis using MRI plus three-dimensional reconstruction software. Magn Reson Imaging 2004;22:1125–1129. 2. Howell SM, Gittins ME, Gottlieb JE, et al: The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. 3. Simmons R, Howell SM, Hull ML: Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg Am 2003;85A:1018–1029. 4. Goss BC, Howell SM, Hull ML: Quadriceps load aggravates and roofplasty mitigates active impingement of anterior cruciate ligament grafts against the intercondylar roof. J Orthop Res 1998;16:611–617. 5. Goss BC, Hull ML, Howell SM: Contact pressure and tension in anterior cruciate ligament grafts subjected to roof impingement during passive extension. J Orthop Res 1997;15:263–268. 6. Howell SM, Clark JA, Farley TE: A rationale for predicting anterior cruciate graft impingement by the intercondylar roof. A magnetic resonance imaging study. Am J Sports Med 1991;19:276–282. 7. Howell SM, Taylor MA: Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg Am 1993;75:1044–1055. 8. Howell SM, Berns GS, Farley TE: Unimpinged and impinged anterior cruciate ligament grafts: MR signal intensity measurements. Radiology 1991;179:639–643. 9. Howell SM, Clark JA, Blasier RD: Serial magnetic resonance imaging of hamstring anterior cruciate ligament autografts during

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10.

11.

12.

13.

14.

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the first year of implantation. A preliminary study. Am J Sports Med 1991;19:42–47. Howell SM, Clark JA, Farley TE: Serial magnetic resonance study assessing the effects of impingement on the MR image of the patellar tendon graft. Arthroscopy 1992;8:350–358. Watanabe BM, Howell SM: Arthroscopic findings associated with roof impingement of an anterior cruciate ligament graft. Am J Sports Med 1995;23:616–625. Howell SM, Taylor MA: Brace-free rehabilitation, with early return to activity, for knees reconstructed with a double-looped semitendinosus and gracilis graft. J Bone Joint Surg Am 1996;78:814–825. Shelbourne KD, Kerr B: The relationship of femoral intercondylar notch width to height, weight, and sex in patients with intact anterior cruciate ligaments. Am J Knee Surg 2001;14:92–96. Howell SM, Barad SJ: Knee extension and its relationship to the slope of the intercondylar roof. Implications for positioning the tibial tunnel

15.

16.

17.

18. 19.

in anterior cruciate ligament reconstructions. Am J Sports Med 1995;23:288–294. Markolf KL, Hame SL, Hunter DM, et al: Biomechanical effects of femoral notchplasty in anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:83–89. Howell SM: Principles for placing the tibial tunnel and avoiding roof impingement during reconstruction of a torn anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 1998;6: S49–S55. Howell SM, Lawhorn KW: Gravity reduces the tibia when using a tibial guide that targets the intercondylar roof. Am J Sports Med 2004;32:1702–1710. www.drstevehowell.com/ezloc_video.cfm. Cuomo P, Edwards A, Giron F, et al: Validation of the 65 degrees Howell guide for anterior cruciate ligament reconstruction. Arthroscopy 2006;22:70–75.

The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction INTRODUCTION The correct placement of the femoral tunnel is very essential for the success of the anterior cruciate ligament (ACL) reconstruction. The transtibial drilling of the femoral tunnel has been very much popularized because of its simplicity and good visualization. However, there is evi­ dence that drilling the femoral tunnel through the tibial tunnel can result in a nonanatomical placement of the graft in the femur.1 In the past, drilling the femoral tunnel more laterally at the medial surface of the lateral femoral condyle (LFC) (2 or 10 o’clock) has been proposed for better functional results, especially to avoid not only the anterior drawer but also the pathological rotation of the tibia.2–4 Recently it was shown the tension curve of grafts in the 9-o’clock position is similar to the characteristic pattern of the normal ACL’s tension curve.5 To reach this position (centered at 2 or 10 o’clock with the lowest point near 9 or 3 o’clock), the anteromedial portal is essential. Thus, the anteromedial portal has become more and more attractive lately, and a large num­ ber of orthopaedic surgeons prefer this portal.6–12

ADVANTAGES The advantages of this technique are as follows: 1 Easy manipulation of the instruments to drill the tunnel in any position at the medial side of the LFC without considering the placement of the tibial tunnel.

2 The femoral and tibial tunnels are drilled separately. Thus, one can choose the desired placement of the femoral tunnel without considering the placement of the tibial tunnel. 3 There is no risk of enlarging the tibial tunnel posteriorly, which can lead to poor fitting and stabilization of the graft in the tunnel.

19 CHAPTER

Manfred Bernard Stavros Ristanis Vassilis Chouliaras Hans Paessler Anastasios Georgoulis

4 By using bone–patellar tendon–bone (BPTB) graft, there is not any divergence when placing the interference screw. 5 In two-bundle ACL reconstruction, it is easier to choose the two entry points. 6 The drilling can be performed with the knee flexed to 120 degrees. In this position the 10-o’lock and also the 9-o’clock position can easily be reached without the risk of a blow­ out fracture of the dorsal corticalis of the femoral condyle. 7 The correct rotation of the graft insertion toward the long femur axis (important to restore the anteromedial and posterolateral bundle using BPTB graft) is easily found because it is parallel to the tibia plateau in the 120-degree flexion position.

TECHNIQUE The technique is as follows: 1 Place the anterolateral portal for the arthroscope 2 to 3 cm higher than the tibial plateau between the lateral distal border of 129

Anterior Cruciate Ligament Reconstruction the patella and the LFC. Place the anteromedial portal 1 cm higher than the tibial plateau and very close to the medial border of the patellar tendon. 2 Resect the ligamentum mucosum and, if needed, pieces of infrapatellar fat for better visualization. In 90 degrees of flexion, débride the posterior surface of the medial side of the LFC from soft tissues. The posterior margin of the notch must be clearly identified to ensure an over-the-top position. This identification is very important to place the femoral tunnel as far posteriorly as desired. Introduce a femoral guide (6 mm offset for an 8-mm hamstring graft or 7 mm offset for a 10-mm BPTB graft) through the medial portal. 3 Slowly flex the knee to 120 degrees, and check for good visualization. Sometimes, higher fluid pressure is demanded, or parts of the fat pad have to be removed to have good visualization of the femoral footprint of the ACL. The center of the femoral tunnel is the center of the ACL footprint at 10 o’clock in the left knee and 2 o’clock in the right knee. Drill a 2.5-mm guidewire through the LFC with the knee in 120 degrees of flexion; the drill exits from the skin at the lateral side of the femur. In this position (120 degrees of flexion), the drill should be aligned parallel to the tibial plateau. Thus, a dorsal blow-out fracture is surely avoided.

Change the drilling machine and fix it at that end of the wire that exits through the skin. Withdraw the Kirschner wire (K wire) until its inner end is flushed with the bone level of the LFC. Now the ending of the K wire marks the estimated center of ACL insertion (Fig. 19-1). Under fluoroscopic control in strictly lateral projection, superimpose both femoral condyles on the monitor. Measure the position of the end of the K wire using the quadrant method (Figs. 19-2 and 19-3).13 It is not necessary to perform an additional fluoroscopic tunnel view because the quadrant method determines the position of the end of the K wire in the anteroposterior direction as well (Fig. 19-4). Overdrill the K wire if its position is correct; if not, replace the K wire, and repeat the fluoroscopy. 6 Remove a small piece of the entry of the femoral tunnel, where the screw has to be inserted by BPTB graft.

4 If you are certain that the guidewire is in the correct position, overdrill the guidewire with a reamer in the chosen depth (8-mm diameter and 35-mm depth for a hamstring graft stabilized by Endobutton or 10-mm diameter and 25-mm depth for a BPTB graft).

7 Drill the tibial tunnel in 90 degrees of flexion. The entry point is selected close to the anterior border of the medial collateral ligament (MCL). The center of the tibial tunnel in the intraarticular space is slightly medial to the center of the intercondylar region on a line joining the inner edge of the anterior horn of the lateral meniscus and the medial tibial spine. With the knee joint in hyperextension and dorsal drawer position, we check that this point is at least 5 mm dorsal from the roof of the intercondylar notch to avoid an impingement of the graft.

5 If you are not sure about the correct position, the placement of the guidewire should be controlled fluoroscopically (recommended for all arthroscopic procedures) as follows:

8 Introduce the tibial guide, and insert a guidewire at an angle of 60 degrees to the tibial plateau. Overdrill the guide with the desired reamer, and check for possible impingement.

FIG. 19-1 Withdraw the K wire (A) until its end is flush with the wall of the lateral condyle (B).

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19

FIG. 19-3 Quadrant method: taking a strictly lateral radiograph, superimposing both condyles, quartering the sagittal diameter, and quartering the notch height. The center of the anterior cruciate ligament (ACL) insertion is located in the distal corner of the most superoposterior quadrant (arrow).

knee flexion. In this position the anatomy of

the anteromedial and posterolateral bundle is

reconstructed.

12 Performing the double-bundle technique; the line between both femoral drill holes should be parallel to the tibial plateau in 120 degrees of knee flexion to restore the correct course of the bundles. This orientation is only achieved using the anteromedial portal (Fig. 19-5). 13 Using the BPTB graft, insert a screw guide parallel to the bone plug through the small widening of the femoral tunnel. Flex the knee joint to 120 degrees, and insert the screw under visualization. FIG. 19-2 Fluoroscopic control in lateral projection (A). The end of the K wire (red circle) marks the estimated center of the insertion (B).

9 With eyelet K wire, pull a suture to the lateral side of the femur. Pull the suture from the tibial tunnel until the medial side of the tibia is reached. 10 Pull the graft to the desired position, using this suture. Sometimes it is necessary to extend or flex the knee joint to facilitate passing the graft through the tibial and femoral tunnels. 11 Using the BPTB graft, rotate the femoral bone block in the tunnel such that the anatomical angle between the long axis of the insertion area and the long axis of the femur is restored. This is reached by adjusting the corticalis of the bone block parallel to the tibial plateau in 120 degrees of

14 Fix the graft at the tibia in about 25 to 30 degrees of flexion.

POSSIBLE COMPLICATIONS Possible complications include the following: 1 Risk of breaking the posterior femoral cortex if the knee is not in 120 degrees of flexion. 2 Poor visualization by inserting an interference screw in 120 degrees of flexion. In this case, insert the screw in 90 degrees of flexion until the tip is at the femoral tunnel, and then bend the knee joint in 120 degrees of flexion, and insert the screw in this position.

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FIG. 19-4 Example of K wire positioning in true lateral projection (A) and in Frick’s projection (B). The yellow arrows demonstrate the correlation of the endings of the K wires (black points) in both projections if they are even with the bony surface of the condyle. The position in craniocaudal direction in the lateral view corresponds to the clockwise position in the tunnel view. For instance, a positioning at 25% of B (height of the notch) in the lateral view leads to the 1:30 clock position in the anteroposterior view (left knee). A drill hole that is positioned at 0% of B in the lateral projection would be in the high-noon position in Frick’s projection.

120˚

Axis femur

25˚

90˚

26˚

Axis tibia

5˚

A

B

FIG. 19-5 In 120 degrees of knee flexion, the corticalis of bone block should be adjusted toward and parallel to the tibial plateau. Because of the tibial slope, an angle of 25 degrees results between the long axis of the insertion area and the axis of the femur (A). This corresponds to the anatomical inclination angle of 26 degrees between both axes (B). Restoring this correct inclination angle is important to reconstruct the course of the anteromedial and posterolateral bundle. Similar conditions are valid when performing the double-bundle technique. In this case the line between both femoral drill holes should be parallel to the tibial plateau in 120 degrees of knee flexion. This orientation is only achieved using the anteromedial portal.

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The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction

References 1. Arnold MP, Kooloos J, van Kampen A. Single-incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 2. Georgoulis A, Papadonikolakis A, Papageorgiou CD, et al. Threedimensional tibiofemoral kinematics of the anterior cruciate ligamentdeficient and reconstructed knee during walking. Am J Sports Med 2003;31:76–79. 3. Ristanis S, Giakas G, Papageorgiou CD, et al. The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs. Knee Surg Sports Traumatol Arthrosc 2003; 11:360–365. 4. Yagi M, Wong E, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 5. Arnold MP, Verdonschot N, van Kampen A. ACL graft can replicate the normal ligament’s tension curve. Knee Surg Sports Traumatol Arthrosc 2005;13:625–631. 6. Paessler HH. New techniques in knee surgery. Darmstadt, 2003. 7. Scranton PE, Pinczewski L, Auld MK, et al. Outpatient endoscopic quadruple hamstring anterior cruciate ligament reconstruction. Oper Tech Orthop 1996;6:177–180. 8. Giron F, Buzzi R, Aglietti P. Femoral tunnel position in anterior cru­ ciate ligament reconstruction using three techniques. A cadaver study. Arthroscopy 1999;15:750–756. 9. Hertel P, Behrend H, Cierpinski T, et al. ACL reconstruction using bone-patellar tendon-bone press-fit fixation: 10-year clinical results. Knee Surg Sports Traumatol Arthrosc 2005;13:248–255. 10. Chhabra A, Kline AJ, Nilles KM, Harner CD. Tunnel expansion after anterior cruciate ligament reconstruction with autogenous hamstrings: a comparison of the medial portal and transtibial techniques. Arthro­ scopy 2006;22:1107–1112.

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11. Bellier G, Christel P, Colombet P, et al. Double-stranded hamstring graft for anterior cruciate ligament reconstruction. Arthroscopy 2004; 20:890–894. 12. Morgan CD, Stein DA, Leitman EH, Kalman VR. Anatomic tibial graft fixation using a retrograde bio-interference screw for endoscopic anterior cruciate ligament reconstruction. Arthroscopy 2002;18(7):E38. 13. Bernard M, Hertel P, Hornung H, et al. Femoral insertion of the ACL. Radiographic quadrant method. Am J Knee Surg 1997;10:14–22.

Suggested Readings Galla M, Uffmann J, Lobenhoffer P. Femoral fixation of hamstring tendon autografts using the TransFix device with additional bone grafting in an anteromedial portal technique. Arch Orthop Trauma Surg 2004;124:281–284. Georgoulis AD, Papageorgiou CD, Makris CA, et al. Anterior cruciate lig­ ament reconstruction with the press-fit technique: 2–5 years follow-up of 42 patients. Acta Orthop Scand Suppl 1997;275:42–45. Georgoulis AD, Tokis A, Bernard M, et al. The anteromedial portal for drilling of the femoral tunnel for ACL reconstruction. Tech Orthop 2005;20:228–229. Gobbi A, Mahajan S, Tuy B, et al. Hamstring graft tibial fixation: bio­ mechanical properties of different linkage systems. Knee Surg Sports Traumatol Arthrosc 2002;10:330–334. Hantes ME, Dailiana Z, Zachos VC, et al. Anterior cruciate ligament reconstruction using the Bio-TransFix femoral fixation device and ante­ romedial portal technique. Knee Surg Sports Traumatol Arthrosc 2006;14:497–501. Lobenhoffer P, Bernard M, Agneskirchner J. Qualitätssicherung in der Kreuzbandchirurgie. Arthroskopie 2003;16:202–208. Pässler HH, Höher J. Intraoperative Qualitätskontrolle bei der Bohrkanalplat­ zierung zum vorderen Kreuzbandersatz Unfallchirurg 2004;107:263–272.

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20 CHAPTER

Giancarlo Puddu Guglielmo Cerullo Massimo Cipolla Vittorio Franco Enrico Giannì

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The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction INTRODUCTION Arthroscopic controlled retrograde drilling of femoral and tibial sockets and tunnels using a specially designed cannulated drill pin and retrocutter (Fig. 20-1) provides greater flexibility for anatomical graft placement and avoids previous tunnels and intraosseous hardware in revision cases. Inside-out drilling of femoral and tibial sockets minimizes incisions and eliminates intraarticular cortical bone fragmentation of tunnel rims common to conventional antegrade methods. This technique is also ideal for skeletally immature patients because drilling and graft fixation through growth plates may be avoided. Initial tunnel positioning (and not referencing) for cannulated drill guide pin placement is carried out from outsidein. This technique (outside-in/inside-out) combines the advantages of the two-incision and one-incision techniques. In fact, it permits surgeons, as with the two-incision technique, to drill a pin guide from outside to inside in order to obtain the correct anatomical insertion of the anterior cruciate ligament (ACL) (Fig. 20-2), which is otherwise not reproducible from inside-out. This technique permits the surgeon to prepare a femoral and a tibial socket or tunnel by initiating the socket drilling from the intraarticular surfaces in an inside-out method (Fig. 20-3). Since November 2004, our preferred technique for hamstring (autogenous quadrupled semitendinosus/gracilis) ACL reconstruction incorporates the just-mentioned femoral socket creation. In recent years, arthroscopically assisted

ACL reconstruction has become the procedure of choice. Initially, arthroscopic techniques required two incisions for outside-in drilling of bone tunnels, but there has been a trend toward using a single incision with inside-out drilling of the femoral tunnel. Those who advocate the twoincision technique state that they do so primarily because they believe that the two-incision procedure facilitates accurate femoral tunnel placement.1,2 Harner et al3 found no difference in tunnel placement using the two-incision technique, whereas Schiavone et al4 found that the femoral tunnels were significantly more vertical in the one-incision procedure. We have performed two-incision ACL reconstruction routinely since 1977 with very favorable results. The recent variation in our technique affords a reduction in morbidity associated with improved cosmesis and quicker postoperative recovery. A factor related to our success appears to be the result of a more anatomically positioned femoral tunnel, which in our hands is difficult to accomplish with single-incision transtibial femoral socket creation. Arnold et al,1 who examined the arthroscopic appearance of the ACL attachment in fresh frozen cadaver knees, found that the ligament consistently inserted on the lateral wall of the notch. No fibers were found to attach high in the roof. Furthermore, they found that the single-incision technique always missed the anatomical femoral ACL insertion. Another advantage of the retrodrill is that the traditional (outside-in) drilling methods disrupt the proximal tibial cortex with the drill penetration and

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction

20

FIG. 20-1 The 3-mm threaded cannulated drill pin with the retrodrill assembled.

FIG. 20-3 The retrodrill is assembled into the guide pin and begins to create the femoral socket.

FIG. 20-2 The pin is in the correct anatomical position in the notch.

may lead to tunnel widening. Retrodrilling produces a consistently smooth tibial and femoral intraarticular socket or tunnel entrance, maintaining the desired cortical integrity (Fig. 20-4). The retrodrill technique allows preparation of the correct anatomical femoral and tibial socket or tunnel with a very small lateral skin incision or without any skin incisions if the surgeon is using an allograft, and it appears to represent a promising futuristic technique in ACL reconstruction.

FEMORAL TUNNEL PLACEMENT Over the past several decades, bioengineers and orthopaedic surgeons have applied the principles of biomechanics to gain valuable information about the tunnel placement in ACL reconstruction and its relationship to knee stability. Still, both short- and long-term clinical outcomes studies have

FIG. 20-4 The traditional drilling method disrupts the proximal tibial cortex (A); the retrodrill technique produces consistently a smooth tibial entrance, maintaining the desired cortical integrity (B).

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Anterior Cruciate Ligament Reconstruction revealed that 11% to 32% of the patients experience unsatisfactory results after ACL reconstruction.5 The position of an ACL graft is the most critical surgical variable because it has a direct effect on knee biomechanics and, ultimately, on clinical outcome. Currently, limited data are available from prospective studies that identify the optimal intraarticular position of an ACL graft on the femur and tibia. A recent review of the literature by Beynnon et al6 shows that the center of the femoral attachment of an ACL graft should be located along a line parallel to the Blumensaat line, just posterior to the center of the normal ACL’s insertion to bone at either the 10-o’clock position (right knee) or the 2-o’clock position (left knee) when observed through the femoral notch. Graft placement, especially the tunnel on the femoral side, has long been a subject of debate. To date, most surgeons choose to place it in the footprint of the anteromedial bundle of the ACL (i.e., near the 11-o’clock position on the frontal view of the right knee). However, results of biomechanical and clinical research have suggested that it is necessary to place the tunnel more laterally for rotatory knee stability. Yamamoto et al5 compared a lateral and an anatomical tunnel placement using a robotic universal force sensor and concluded that a lateral tunnel placement can restore rotatory and anterior knee stability similarly to an anatomical reconstruction when the knee is near extension. Loh et al7 published a paper studying how well an ACL graft fixed at the 10- and 11-o’clock positions could restore knee function in response to both externally applied anterior tibial and combined rotatory loads by comparing the biomechanical results with each other and with the intact knee. They concluded that the 10-o’clock position more effectively resists rotatory loads when compared with the 11-o’clock position, as evidenced by smaller anterior tibial translation and higher in situ force in the graft. More recently Scopp et al8 performed a biomechanical study on 10 matched pairs of fresh frozen cadaver knees alternately assigned to a standard or an oblique tunnel position (at 10-o’clock) reconstruction. The investigators concluded that an ACL reconstruction using oblique femoral tunnels restored normal knee kinematics. In conclusion, it appears that actually there is a trend toward placing the femoral tunnel more laterally between the anteromedial and posterolateral anterior cruciate footprints (i.e., the 10-o’clock position). Biomechanics helped to clarify that although fixation at 11 o’clock is effective to resist an anterior tibial load, the more lateral 10-o’clock position could achieve better knee stability under rotatory loads (i.e., pivot shift). More recently, Arnold et al9 found that it is possible to replicate the characteristics of the tension curve of the normal ACL with a graft in a tunnel located at the 9-o’clock position.

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SURGICAL TECHNIQUE With the knee flexed at 90 degrees, after removing the remnants of the torn ACL, soft tissue and periosteum are débrided from the lateral wall of the notch. Additional bony notchplasty is performed as needed. The posterior margin of the notch is clearly identified. To locate the desired center of the femoral tunnel, we use a femoral guide recently made by Arthrex (Naples, FL) that keys off the over-the-top position. The guide enters the knee from the anteromedial portal and with its curved hook is fastened to the lateral femoral condyle in the over-the-top position at the 10:30 position for the right knee and the 1:30 position for the left knee. Our guide, with its variable hook, permits us to drill a specially designed cannulated guide pin from outside to inside that emerges in the lateral wall of the notch just 4 to 6 mm anterior to the posterior margin of the notch. When drilled, this creates a tunnel 7 to 10 mm in diameter, which leaves a 0.5- to 1-mm rim of posterior cortex. Reproducing this tunnel with the exact location in the frontal, sagittal, and coronal planes with a guidewire drilled from inside-out is quite impossible, especially if done through a predrilled tibial tunnel. With the guide positioned in the notch, a mini (2-cm) lateral skin and fascia incision is carried out corresponding with the tip of the guide, and the drill sleeve is advanced to the femoral cortex along the lateral aspect of the knee (Fig. 20-5). A cannulated threaded pin (3 mm in diameter) is drilled through the drill sleeve and the femoral condyle until it enters intraarticularly, as observed with the arthroscope (see Fig. 20-2). The correct location is confirmed. Then a mini retrograde cutting drill (retrocutter) (Arthrex) 7 to 10 mm in diameter (depending on the width of the graft that has been previously harvested and measured)

FIG. 20-5 Via the placement of a special femoral guide, a cannulated pin is inserted from outside into the femoral notch.

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction is introduced in the knee from the anteromedial portal already preloaded on a reverse-threaded instrument. As threads of the guide pin engage the retrocutter, the reverse threads of the drill holder facilitate simultaneous disengagement of the retrocutter from the instrument (Fig. 20-6, A ). A handle is set up on the outer end of the pin to permit the manual advancement of the inner end of the pin onto the retrocutter. The cannulated pin is also calibrated in order to easily know the lateral condyle width. Then a socket of 2.5 to 3.5 cm is retrodrilled, pulling the drill from outside (Fig. 20-6, B), leaving 1 cm of intact bone. The retrodrill is then gently pushed back in the joint. Once the retrocutter engages its holder, the drill is reversed; reverse drilling securely engages the retrocutter on the holder and simultaneously disengages the retrocutter from the threaded guide pin. A shaver is used to remove any debris in the joint and to chamfer the tunnels edges, and a suture (#2 FiberStik, Arthrex) is introduced in the joint through the cannulated pin for graft passing. A tibial tunnel of the same diameter is prepared in a routine manner, or a tibial socket can be made in the same way as the femoral (Fig. 20-7) if so planned by the surgeon. The suture is pulled out from the tibial tunnel. The graft (quadruple gracilis and semitendinosus) is marked to locate the exact portion that has to fill the femoral tunnel and is prepared with two #5 Fiberwire (Arthrex) sutures at the femoral end and passed in the knee from the tibial to the

20

femoral tunnel. The fixation sutures exiting the lateral cortex of the femur are passed through a four-hole metal button and tied securely to fix the graft on the femur (Fig. 20-8). Either square or sliding knots can be used for this kind of suspension fixation. The tibial fixation is carried out in a routine way using an interference metal screw coupled with a staple or, more recently, with Fiberwire whipstitches interwoven in the graft and tied around a screw.

PRELIMINARY RESULTS AND CONCLUSIONS Our 70 cases performed from November 2004 to November 2005 (2 to 14 months of follow-up) do not permit a longterm evaluation. No intraoperative complications occurred when performing the retrodrill technique. In three cases the drill was not perfectly engaged in the pin, so we had to retrieve the drill from the joint with a grasper and reposition it onto the cannulated pin. There were no postoperative complications, and the early results evaluated with the International Knee Documentation Committee (IKDC) scoring system are very good. The retrodrill technique seems to be safe and effective for femoral socket preparation, as it is very likely to be for the tibial socket, representing the initial step for a completely “all inside” arthroscopic ACL reconstruction.

FIG. 20-6 The femoral cannulated guide pin engages the retrodrill and simultaneously disengages it from the holding instrument (A); the femoral socket is created by pulling distally, and retrograde drilling is completed to the socket depth planned by the surgeon (B). (Reprinted with permission from Arthrex, Inc., Naples, FL.)

137

Anterior Cruciate Ligament Reconstruction

FIG. 20-7 The 3-mm cannulated drill guide pin is drilled through the tibia and the retrodrill is assembled (A); the tibial socket or tunnel is created, pulling the retrodrill to the depth planned by the surgeon (B). (Reprinted with permission from Arthrex, Inc., Naples, FL.)

References

FIG. 20-8 The button is inserted through the lateral femoral incision, and with two limbs of #5 reinforced suture (Fiberwire, Arthrex), the graft is fixed to the femur.

138

1. Arnold MP, Kooloos J, van Kampen A. Single incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 2. Khon D, Busche T, Carls J. Drill hole position in endoscopic anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthroscop 1998;6:S13–S15. 3. Harner C, Marks P, Fu F, et al. Anterior cruciate ligament reconstruction: endoscopic versus two incision technique. Arthroscopy 1994; 10:502–512. 4. Panni AS, Milano G, Tartarone M, et al. Clinical and radiographic results of ACL reconstruction: a 5- to 7-year follow-up study of outside-in versus inside-out reconstruction technique. Knee Surg Sports Traumatol Arthrosc 2001;22:77–85. 5. Yamamoto Y, Hsu WH, Woo SL-Y, et al. Knee stability and graft function after anterior cruciate ligament reconstruction: a comparison of a lateral and an anatomical femoral tunnel placement. Am J Sports Med 2004;32:1825–1832. 6. Beynnon BD, Johnson RJ, Abate J, et al. Treatment of anterior cruciate ligament injuries, part II. Am J Sports Med 2005;33:1751–1767. 7. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304.

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction 8. Scopp JM, Jasper LE, Belkoff SM, et al. The effect of oblique femoral tunnel placement on rotational constraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294–299. 9. Arnold MP, Verdonschot N, Van Kampen A. ACL graft can replicate the normal ligament’s tension curve. Knee Surg Sports Traumatol Arthrosc 2005;13:625–631.

Suggested Readings Andersen H, Dyhre-Poulsen P. The anterior cruciate ligament does play a role in controlling axial rotation in the knee. Knee Sur Sports Traumatol Arthrosc 1997;5:145–149.

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Beynnon BD, Johnson RJ, Abate JA, et al. Treatment of anterior cruciate ligament injuries, part I. Am J Sports Med 2005;33:1579–1602. Markolf KL, Hame S, Hunter DM, et al. Effects of femoral tunnel placement on knee laxity and forces in an anterior cruciate ligament graft. J Orthop Res 2000;20:1016–1024. Puddu G, Cerullo G. My technique in femoral tunnel preparation: the retrodrill technique. Tech Orthop 2005;20:224–227. Ristanis S, Stergiou N, Patras K, et al. Excessive tibial rotation during high-demand activities is not restored by anterior cruciate ligament reconstruction. Arthroscopy 2005;1:1323–1329. Sommer C, Friederich NF, Muller W. Improperly placed anterior cruciate ligament grafts: correlation between radiological parameters and clinical results. Knee Surg Sports Traumatol Arthrosc 2000;8:207–213.

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Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

Andrew A. Amis*

INTRODUCTION

CHAPTER

In order to perform a successful anterior cruciate ligament (ACL) reconstruction, the surgeon must make a number of steps that require correct judgment and execution, but there is evidence that the most frequent cause of failure is malpositioning of the graft tunnel in the femur.1 This is not surprising because of the anatomy of the interior of the knee joint and the difficulty of seeing the femoral attachment of the ACL. Because the surgeon views the interior of the intercondylar notch when the knee is flexed, the ACL attachment is carried back into the furthest recess of the knee. This means that there is plenty of scope to err with the tunnel placement if the ACL attachment is not visualized clearly. In particular, the undulating surface of the femoral intercondylar notch includes a transverse ridge or bulge that should come between the observer and the proximal part of the ACL attachment; the inexperienced surgeon may believe that this ridge is the posterior outlet of the notch and then place the graft tunnel shallow to that ridge in a nonanatomical position. The frequency of this error has led to common usage of the term “resident’s ridge” to describe this anatomical feature. The aim of this chapter is to describe the evolution of knowledge regarding ACL graft placement on the femur, which relates closely to our understanding of the function of the ACL *The author thanks all the surgeons engaged in ACL surgical research who have generously shared their expertise with him recently in his travels around the world, which were undertaken with the generous support of the BREG-ACL Study Group International Research Professorship.

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itself. There has been a recent move toward “anatomical” reconstructions, with two grafts in parallel, attempting to reproduce two functional fiber bundles of the ACL. This has prompted a better appreciation of the natural ACL attachment anatomy when performing a conventional single-bundle reconstruction. The tibial attachment is not considered here because changes of the femoral attachment have a much larger effect on ACL graft tension and length changes.2 In this chapter, two distinct sets of terminology will be used to describe femoral graft tunnel positions: (1) anatomical nomenclature for describing positions when the knee is in extension (anterior-posterior, proximal-distal) and (2) surgical nomenclature for describing what the surgeon views when the knee is flexed approximately 90 degrees (high-low, deep-shallow, respectively).3

FUNCTIONAL ANATOMY OF THE ANTERIOR CRUCIATE LIGAMENT RELATED TO GRAFT TUNNELS The ACL has a complex fiber structure composed of many fascicles bound together within a synovial covering layer. The fibers are not arranged simply in parallel, and this gives rise to the cross-sectional area being less at the midlength than at the bony attachments: the fibers must splay out toward the bones.4 The functional significance of this architecture is not understood. However, at a gross level, the fibers of the ACL are arranged as a flat band, and all are

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction tensed when the knee is extended (Fig. 21-1, A ). This fiber band is oriented in a sagittal plane so that the ACL fits into and fills the narrow slot between the posterior cruciate ligament (PCL), which occupies most of the width of the intercondylar notch, and the lateral femoral condyle. The sagittal plane of the ACL orientation means that it attaches to the tibia over an area that is oriented anteroposterior (AP). The ACL attaches to the femur over an area that is oriented from anteroproximal to posterodistal.5 This femoral attachment is close to and bounded posteriorly by the condylar articular cartilage and has an overall alignment approximately 35 degrees posterior-distal to the axial.6 When the knee flexes, the axis of rotation moves within the distal femur and the kinematics are affected by the loads

21

imposed on the knee, but the overall effect in the intact knee is that the most anterior fibers of the ACL remain close to a constant length and thus are often described as being “isometric.” Meanwhile, the more posterior the fibers, the more they slacken as the knee flexes, up to 90 degrees flexion2,7–10 (Fig. 21-1, B). These length change patterns have been measured in a number of studies,2,7,11 and it is generally accepted that an “isometry map” can be derived from such measurements.2,9,10 A modern surgical navigation system can produce such maps in response to the surgeon moving the knee during ACL reconstruction procedures, giving a patient-specific feedback on the likely length changes associated with choices of graft tunnel positions around the intercondylar notch12 (Fig. 21-2).

ANTERIOR CRUCIATE LIGAMENT ISOMETRY AND RECONSTRUCTION AMB tight

PLB tight

A

AMB tight

PLB slack in flexion

B FIG. 21-1 A, The anterior cruciate ligament (ACL) is arranged to form a parallel-fibered, ribbon-like structure when the knee is extended; the fibers are tensed in both the anteromedial bundle (AMB) and posterolateral bundle (PLB). B, When the knee flexes, the PLB slackens and its femoral attachment passes between the tight AMB and the wall of the notch; this causes the ACL to twist with knee flexion.

The observation that the anterior fibers of the ACL remained tight across the range of knee flexion, whereas the more posterior parts slackened, led to the belief that the anterior fibers were the most important. This was reinforced by the finding that the more anterior fibers had a greater material failure strength,13 which suggests that they have adapted to a more mechanically demanding role. A similar finding has been made for the PCL.14 These findings have been correlated with a higher collagen density in the anterior fiber bundles of both the ACL and PCL.15 A more practical reason to place a graft isometrically is that this implies the graft will not be subjected to cyclical length changes when the knee is moving, thus helping to protect it from fatigue or loosening effects. For example, O’Meara et al16 reported that isometric grafts survived cyclical motion in a continuous passive motion machine, whereas nonisometric grafts did not. The problem with this line of reasoning is that isometry measurements depend on the ACL being intact; otherwise the kinematics may be abnormal. Even when the ACL is intact, the isometric area on the femoral condyle is influenced sensitively by the loads imposed on the knee while it is being moved. This was shown by Zavras et al,17 who published a map showing a range of different recommended isometric graft locations from the previous literature (Fig. 21-3). Their reproduction of the published works confirmed that isometric behavior could be found reliably for attachment points only at the extreme anteroproximal corner of the natural ACL attachment area.2,9 This means that “isometric” ACL reconstructions are nonanatomical, with the femoral graft tunnel centered higher and deeper in the notch (with the knee flexed) than the natural attachment area. Despite this, the mainstream of opinion through the 1990s favored femoral graft tunnels placed isometrically. 141

Anterior Cruciate Ligament Reconstruction A

L

M

P

M

Although many clinical papers were published to report a high percentage of good and excellent results, there remained a high level of interest in ACL research and development, reflecting an underlying dissatisfaction with clinical outcome and a desire to find ways of improvement. One of the underlying principles that emerged from the isometry research studies was that there is a transition line between attachments that causes graft tightening or slackening with knee flexion.2 The transition line passes through the isometric point at the anteroproximal edge of the ACL attachment and from there runs distal and slightly posterior.2,8,9 Attachments anterior to the transition line lead to graft tightening with knee flexion, whereas grafts posterior to the transition line slacken (Fig. 21-4). At present, the principal method for objective assessment of the restoration of normal mechanics to the knee after ACL reconstruction is the measurement of tibiofemoral anterior translation laxity; that is, how far anteriorly the tibia moves in response to a known displacing force at

142

L

FIG. 21-2 A map of fiber attachment length changes produced during anterior cruciate ligament (ACL) reconstruction surgery by a navigation system. The “contour lines” represent areas with a given length change measured over a range of knee flexion. They converge toward a central zone of minimal length change. (With thanks for permission to Dr. Philippe Colombet, Merignac, France.)

a given angle of knee flexion. Very little work has been done to examine how well different ACL graft positions can restore anterior laxity to normal across the range of knee flexion. Even an incorrect graft placement might restore anterior drawer to normal at one angle of knee flexion (by adjusting the tension appropriately), but then it might behave abnormally and either overconstrain or allow excessive laxity as the knee moves away from the posture where the graft had been tensed. A study of alternative graft attachments investigated the effect of moving to different attachment points either at or around the isometric area on the femur.18 The in vitro study used artificial grafts secured into a barrel that was centered at the femoral isometric point (which had been ascertained by isometry measurements while the ACL was intact). Five attachment points were investigated: isometric, then anteroproximal, anterodistal, posteroproximal, or posterodistal to the isometric point, as shown in Fig. 21-5. It was found to be possible to restore tibiofemoral anterior

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

S1

F

21

H Isometric drill hole

AM P

F

26

PP Superior

T

An

18

AA

P

B

Central Inferior

15

Original ACL Proposed insertions

L

11 24

5 mm

FIG. 21-3 Published isometric graft attachment sites: S1, Sidles et al10; F, Friederich and O’Brien9; H, Hefzy et al2; L, Cazenave and Laboureau31; B, Blankevoort et al32; An (anatomic), Odensten and Gillquist.33 (Reproduced from Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28–33, with kind permission of Springer Science and Business Media.)

pp ap

pd ad

FIG. 21-4 The transition line between graft attachments, which leads to graft tightening or slackening, passes posterodistally from the isometric area. Anterior attachments cause tightening, and posterior attachments cause slackening as the knee flexes.

FIG. 21-5 The five anterior cruciate ligament (ACL) graft attachment points investigated by Zavras et al.17 The central isometric point and the more posterior points lead to restoration of normal anterior laxity across the range of knee flexion; the posterodistal point is close to the center of the anatomical ACL attachment area. ad, Anterodistal; ap, anteroproximal; pd, posterodistal; pp, posteroproximal. (Reproduced from Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28-33, with kind permission of Springer Science and Business Media.)

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Anterior Cruciate Ligament Reconstruction laxity close to normal across the range of knee flexion investigated, with attachments that were either on that transition line or just posterior to it.18 The tendency of anterior femoral attachments to move away from the matching tibial attachment, and therefore cause the graft to tighten with knee flexion, led to overconstraint of the flexed knee; this was accompanied by elevated graft tension as the knee flexed. Grafts placed distal and posterior to the isometric point, which meant that they were in the anatomical ACL attachment, restored anterior laxity to that of the intact knee across the range of knee flexion investigated.

ANATOMICAL SINGLE-BUNDLE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION The trend from isometric toward anatomical graft placement was encouraged by growing evidence of limitations with isometric grafts. In particular, their placement high in the notch meant that they were close to the center of the knee, which is not efficient if they are supposed to limit tibial rotational laxity. There has been a growing awareness that restoration of physiological anterior laxity, as measured routinely by a KT-1000 or similar device, is not sufficient to define a return to the knee working normally and that tibial rotational laxity is also important. The drawback of grafts placed high in the notch has been demonstrated in vivo after ACL reconstruction: one study found that the majority of knees with a patellar tendon ACL reconstruction had traces of residual rotational laxities during pivot-shift testing (a mini-pivot remained).19,20 Other studies have found that the limb with a reconstructed ACL had a persistence of abnormal tibial rotation during gait analysis.21,22 In addition, Amis and Dawkins7 cut the fiber bundles sequentially and measured the reduction in force needed to induce a given tibial anterior translation. The reduction in force needed to displace the tibia indicated the contribution that the cut fiber bundle had made to resisting tibial anterior drawer. It was found that the anteromedial fiber bundle was dominant in the flexed knee, as expected, knowing that the rest of the ACL was then slackened (see Fig. 21-1, B). Conversely, the posterolateral fiber bundle was dominant when the knee was near extension. This, of course, is the posture in which knee stability is most important, when standing. Such observations have led to a trend toward more anatomical graft placement. In single-bundle ACL reconstruction, that means that the tunnel should be placed at the center of the ACL attachment, which is distal and posterior to the isometric point. During surgery, with the knee flexed, this translates into a tunnel that is lower on the lateral side wall of the notch and also more shallow toward the surgeon compared with the isometric point. In practice, this translates 144

into continuing to use a fixed offset from the posterior outlet but bringing the guide around from approximately the 11-o’clock or 11:30 position to approximately the 10-o’clock position in a right knee. If there is any doubt about the accuracy of finding this point, in a chronic case in which the ACL remnants have disappeared, a guidewire may be placed and checked radiographically using the quadrant method of Bernard et al,23 who documented the center of the femoral ACL attachment. A method to navigate to this point3 is shown in Fig. 21-6. Studies on cadaveric knees24,25 have found that the anatomical tunnel placement (at the 10 o’clock position) led to better control of tibial rotation than did a tunnel placed higher in the notch (at the 11 o’clock position).

ANATOMICAL DOUBLE-BUNDLE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Recently there has been increasing interest in attempting to more closely achieve an anatomical reconstruction using a double-bundle graft. Although some studies have used double grafts passing to or from single tunnels in either the tibia or femur, it is usually accepted that an anatomical reconstruction has two grafts in parallel when the knee is extended, with two tunnels in each of the tibia and femur. The femoral ACL attachment has been split into the two bundle areas in Fig. 21-7.

High

0%

Shallow

Deep 28%

100% 100%

25%

Low

FIG. 21-6 The center of the femoral attachment of the anterior cruciate ligament (ACL) can be found by navigation in percentage terms from the over-the-top position in deep–shallow and high–low directions in the flexed knee.3 Bernard et al23 found the center of the ACL attachment to be 25% more shallow and 28% lower from the over-the-top position.

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

21

AM

AMB PLB

AC

PL

PCL

FIG. 21-7 The femoral anterior cruciate ligament (ACL) attachment with the areas of the anteromedial (AMB) and posterolateral (PLB) fiber bundles.

If the knee is viewed arthroscopically, the anatomical ACL attachment area may be visualized via an anteromedial portal; the viewpoint across the notch gives a better appreciation of depth than can be gained when looking along the lateral side wall from an anterolateral portal.26 The differences in the double-bundle attachment sites, compared with the conventional tunnel high and deep in the notch, then become apparent. The tunnel for the anteromedial graft will still be close to the posterior outlet of the notch but will now be brought down to approximately the 10:30 position. Because of the sloping orientation of the posterior outlet of the notch, moving to the lateral wall also takes the graft tunnel toward the surgeon, which is more shallow (more distal). The tunnel for the posterolateral graft is farther distal and posterior anatomically, which means that it is lower on the side wall of the notch and much more shallow than the first tunnel (Fig. 21-8). Typical positions will be at the 9-o’clock orientation, with an offset sufficient to maintain a bone bridge between the tunnel mouths. With autogenous hamstring tendon grafts, the tunnels are typically 6 mm in diameter, and an offset of 8 mm between the tunnel centers maintains a bone bridge and matches the spacing of the natural fiber bundle attachments. This position will be much closer to the surgeon than with a conventional reconstruction and should also be low enough that the posterior edge of the tunnel is close to the articular cartilage margin at the place where it is closest to the tibia6 (see Fig. 21-8). Various instruments are being developed to allow the second (posterolateral) tunnel to be located relatively easily at a fixed offset distance from the first (anteromedial) tunnel,27 which can itself be located using a conventional offset drill guide hooked over the posterior rim of the intercondylar notch.

FIG. 21-8 The typical positions of double tunnels in a right knee flexed 90 degrees, viewed from an anteromedial portal. Note how the anteromedial bundle tunnel (AM) is close to the over-the-back position (asterisk) and that the posterolateral bundle tunnel (PL) is shallow (distal) and low (posterior) compared with the AM tunnel. Interrupted line, Approximate boundary of ACL attachment; AC, articular cartilage; PCL, posterior cruciate ligament. (Illustration provided kindly by Dr. F. Giron, Prima Clinica Ortopedica, Florence, Italy.)

DISCUSSION This chapter has outlined some of the thinking and research behind the recent evolution of femoral ACL graft tunnel placement. At one period the predominant doctrine was that the tunnel placement should produce isometric graft behavior, but that resulted in the tunnel being placed high in the notch, which was not anatomical. The mainstream of opinion has more recently moved toward an acceptance of anatomical graft placement, a philosophy to which some surgeons have always adhered. However, until recently there has been little interest in making a comparison between these approaches. Biomechanical researchers have produced evidence in vitro to support a move toward placing the ACL graft more anatomically, which is onto the lateral side wall of the intercondylar notch, at approximately 10 o’clock, and more shallow compared with the conventional isometric placements. A more recent development is the anatomical double-bundle reconstruction,28,29 but at present there is no reliable clinical evidence to support a change from a single-bundle ACL reconstruction.30

References 1. Getelman MH, Friedman MJ. Revision anterior cruciate ligament surgery. J Am Acad Orthop Surg 1999;7:189–198.

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Anterior Cruciate Ligament Reconstruction 2. Hefzy MS, Grood ES, Noyes FR. Factors affecting the region of most isometric femoral attachments. Part II: the anterior cruciate ligament. Am J Sports Med 1989;17:208–216. 3. Amis AA, Beynnon B, Blankevoort L, et al. Proceedings of the ESSKA scientific workshop on reconstruction of the anterior and posterior cruciate ligaments. Knee Surg Sports Traumatol Arthrosc 1994;2:124–132. 4. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 5. Giron F, Cuomo P, Aglietti P, et al. Femoral attachment of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14:250–256. 6. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon. Arthroscopy 2004;20:1015–1025. 7. Amis AA, Dawkins GPC. Functional anatomy of the anterior cruciate ligament—fibre bundle actions related to ligament replacements and injuries. J Bone Joint Surg 1991;73B:260–267. 8. Amis AA, Zavras TD. Review article: isometricity and graft placement during anterior cruciate ligament reconstruction. Knee 1995;2:5–17. 9. Friederich NF, O’Brien WR. Functional anatomy of the cruciate ligaments. In Jakob RP, Staubli HU (eds): The knee and the cruciate ligaments. Berlin, 1992, Springer Verlag, pp 78–91. 10. Sidles JA, Larson RV, Garbini JL, et al. Ligament length relationships in the moving knee. J Orthop Res 1988;6:583–610. 11. Sapega AA, Moyer RA, Schneck C, et al. Testing for isometry during reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1990;72A:259–267. 12. Colombet P. Personal communication December, 2005. 13. Butler DL, Guan Y, Kay MD, et al. Location-dependent variations in the material properties of the anterior cruciate ligament. J Biomech 1992;25:511–518. 14. Race A, Amis AA. The mechanical properties of the two bundles of the human posterior cruciate ligament. J Biomech 1994;27:13–24. 15. Mommersteeg TJ, Blankevoort L, Kooloos JG, et al. Nonuniform distribution of collagen density in human knee ligaments. J Orthop Res 1994;12:238–245. 16. O’Meara PM, O’Brien WR, Henning CE. Anterior cruciate ligament reconstruction stability with continuous passive motion. Clin Orthop 1992;277:201–209. 17. Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28–33. 18. Zavras TD, Race A, Amis AA. The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior-posterior laxity patterns. Knee Surg Sports Traumatol Arthrosc 2005;13:92–100.

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19. Amis AA, Bull AMJ, Lie DTT. Biomechanics of rotational instability and anatomic anterior cruciate ligament reconstruction. Op Tech Orthop 2005;15:29–35. 20. Bull AMJ, Earnshaw PH, Smith A, et al. Intraoperative measurement of knee kinematics in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2002;84B:1075–1081. 21. Ristanis S, Giakas G, Papageorgiou CD, et al. The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs. Knee Surg Sports Traumatol Arthrosc 2003;11:360–365. 22. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 23. Bernard M, Hertel P, Hornung H, et al. Femoral insertion of the ACL. Radiographic quadrant method. Am J Knee Surg 1997;10:14–21. 24. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304. 25. Scopp JM, Jasper JE, Belkoff SM, et al. The effect of oblique femoral tunnel placement on rotational contraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294–299. 26. Fu F. Personal communication August, 2005. 27. Christel P, et al. Personal communication April, 2005. 28. Radford WJP, Amis AA. Biomechanics of a double prosthetic ligament in the anterior cruciate deficient knee. J Bone Joint Surg 1990;73B:1038–1043. 29. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 30. Adachi N, Ochi M, Uchio Y, et al. Reconstruction of the anterior cruciate ligament: single versus double-bundle multistranded hamstring tendons. J Bone Joint Surg 2004;86B:515–520. 31. Cazenave A, Laboureau JP: Isometric reconstruction of the anterior cruciate ligament. Pre- and peri-operative determination of the femoral isometric point. French J Orthop Surg 1990;4:255–259. 32. Blankevoort L, Huiskes R, van Kampen A. ACL reconstruction: simply a matter of isometry? In: Passive motion characteristics of the human knee joint—experiments and computer simulations. PhD thesis, University of Nijmegen, 1991, 151–162. 33. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for its reconstruction. J Bone Joint Surg 1985;67A:257–262.

SUB PART II DOUBLE ANTEROMEDIAL AND POSTEROLATERAL FEMORAL-

TUNNEL FORMATION

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons INTRODUCTION The anterior cruciate ligament (ACL) is composed of the anteromedial bundle (AMB) and the posterolateral bundle (PLB), each with a different function.1–3 Since 2000, the author has reported the surgical principle4 and the latest procedure5 for an anatomical doublebundle ACL reconstruction that is intended to anatomically reconstruct the AMB and the PLB. In addition, the author’s team reported a prospective cohort study to evaluate this anatomical double-bundle procedure in comparison with single-bundle and nonanatomical double-bundle ACL reconstruction procedures using hamstring tendon grafts.6 Our procedure has several noteworthy characteristics. First, all four ends of two tendon grafts are grafted at the center of the anatomical attachment of the AMB or the PLB, not only on the femur but also on the tibia. Second, we use the transtibial tunnel technique to create femoral tunnels. Third, we use the hamstring tendonhybrid graft,7,8 in which the femoral end is connected with an Endobutton CL and the tibial end is connected with a polyester tape. Fourth, we fix the polyester tape portion of the graft onto the tibia with two staples at 10 degrees of knee flexion, simultaneously applying a 30N load to each graft. In this chapter, the surgical principle and the procedure of our anatomical double-bundle ACL reconstruction are explained.

PROCEDURE

22 CHAPTER

Kazunori Yasuda

Preparation for Arthroscopic Surgery Surgery is performed with an air tourniquet in the standard supine position. An approximately 3-cm-long oblique incision is made in the anteromedial portion of the proximal tibia. The semitendinosus and gracilis tendons are harvested using a tendon stripper in the figure-four knee position. When the semitendinosus tendon is thick and long enough, the gracilis tendon is not harvested. At the beginning of arthroscopic surgery, a surgeon sits beside the knee joint of the patient. An edge of a drape is attached to a lumbar portion of the surgeon so that the patient’s leg hanging beside the table can be put on the surgeon’s knee in a sterile condition. This setup allows the surgeon to control the patient’s knee position using the surgeon’s own knee. An arthroscope is inserted through the lateral infrapatellar portal. After a routine arthroscopic examination, a remnant of the torn ACL is resected, leaving 1-mm-long ligament tissue at the femoral and tibial insertions, which can be used as landmarks for inserting guidewires.

Creation of Tibial Tunnels In ACL reconstruction procedures with the transtibial tunnel technique, the greatest key to success is to create a tibial tunnel with an

147

Anterior Cruciate Ligament Reconstruction

D TP

* A

C

B

B appropriate three-dimensional (3D) direction. In other words, a tibial tunnel should be created so that a guidewire for femoral tunnel creation can be easily inserted at a targeted point on the lateral condyle through the tibial tunnel. To create such a tibial tunnel, we use a specially designed wire guide, called a wire navigator (Fig. 22-1, A), which was developed in our previous study.7,8 This device is composed of a navi-tip and a wire sleeve. The navi-tip consists of sharp tibial and femoral indicators. The axis of the wire sleeve passes through the tip of the tibial indicator (Fig. 22-1, B). First, a tibial tunnel for the PLB is created. The navi-tip is introduced into the joint cavity through 148

FIG. 22-1 The wire navigator (A) and the concept of wire navigation for the tibia (B). The wire navigator is composed of a navi-tip (A) and a wire sleeve (B). The navi-tip consists of the tibial indicator (C) and femoral indicator (D). The axis of the wire sleeve is passed through the tip of the tibial indicator. Keeping the tibial indicator at the targeted point on the tibia, we aim the femoral indicator at the targeted point (TP) on the femur. Subsequently, the direction and the insertion point of the wire are automatically determined.

the medial infrapatellar portal. The surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal. The tibial indicator of the navi-tip is placed at the center of the PLB footprint on the tibia, which is located at the most posterior aspect of the area between the tibial eminences and 5 mm anterior to the posterior cruciate ligament (Fig. 22-2). Keeping the tibial indicator on this point, we aim the femoral indicator at the center of the PLB footprint on the femur (Fig. 22-3, A), which is precisely explained in the next section, and the proximal end of the extraarticularly located wire sleeve is fixed on the anteromedial aspect of the tibia through the skin incision made

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

FIG. 22-2 Two tibial tunnel outlets are shown. They are created at the center of the normal attachment of the anteromedial bundle (AMB) and posterolateral bundle (PLB).

for the graft harvest. The proximal end and the direction of the wire sleeve are automatically determined depending on the direction of the intraarticular navi-tip (see Fig. 22-1, B). A Kirschner wire of 2 mm in diameter is drilled through the sleeve in the tibia. According to our basic studies, this tunnel does not injure this ligament because the insertion point of the wire on the anteromedial aspect of the tibia is located several millimeters anterior to the medial collateral ligament.4 The first tunnel is made with an approximately 6-mm cannulated drill corresponding to the measured diameter of the prepared substitute.

22

Next, a Kirschner wire for the AMB reconstruction is drilled using the same wire navigator. The tibial indicator is placed at the center of the tibial footprint of the AMB, which is located at a point approximately 7 mm anterior to the center of the first tunnel (see Fig. 22-2). Keeping the tibial indicator on this point, we then aim the femoral indicator at the center of the femoral footprint of the AMB (Fig. 22-3, B). The wire sleeve is fixed on the anteromedial cortex of the tibia. A Kirschner wire is then drilled through the sleeve in the tibia. The knee should be extended to ensure that the tip of the second wire is located at a point 5 mm posterior to the anterior edge of the roof in the intercondylar notch. The second tunnel is drilled with an approximately 7-mm cannulated drill corresponding to the measured diameter of the prepared substitute. Subsequently, two intraarticular outlets are aligned in the sagittal plane (see Fig. 22-2).

Creation of Femoral Tunnels In the anatomical double-bundle procedure, it is essential to precisely understand the attachment of the main ACL fibers that should be reconstructed in ACL reconstruction. Although the normal ACL has a wide footprint on the lateral condyle,9–11 the author has found that the main ACL fiber attachment that should be reconstructed in ACL reconstruction is in the form of an egg, with its long axis inclined toward the posterior direction by 30 degrees

FIG. 22-3 The navi-tip of the wire navigator in an arthroscopic visual field. First (A), keeping the tibial indicator at the center of the posterolateral bundle (PLB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the PLB footprint on the femur. Then (B), keeping the tibial indicator at the center of the anteromedial bundle (AMB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the AMB footprint on the femur.

149

Anterior Cruciate Ligament Reconstruction to the long axis of the femur on the medial surface of the lateral femoral condyle4 (Fig. 22-4). First, a Kirschner wire is drilled at the center of the femoral footprint of the AMB through the second tibial tunnel, using the offset guide system (Transtibial Femoral ACL Drill Guide, Arthrex, Naples, FL). This point is located at the point 5 to 6 mm distal from the back of the femur (see Fig. 22-4). This point is consistent with the 1:30 (or 10:30) orientation for the left (or right) knee. Using this wire as a guide, a tunnel is made with a 4.5-mm cannulated drill. The length of the tunnel is measured with a scaled probe. Then, to precisely observe the lateral condyle in the arthroscopic visual field, the portal for the arthroscope is changed to the medial infrapatellar one. We have developed a reproducible method to identify the targeted point in the arthroscopic visual field.4 When the surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal, we can draw an imaginary vertical line through the contact point between the femoral condyle and the tibial plateau in the arthroscopic visual field (see Fig. 22-4). The center of the attachment of the PLB is located approximately at the crossing point between the vertical line and the long axis of the ACL attachment. Therefore, when the remnant of the ACL is observed on the lateral condyle, this point can be easily determined. If the remnant of the ACL is not identified on the lateral condyle, the center of the attachment of the PLB can be determined as the point 5 to 8 mm anterior to the edge of the joint cartilage on

FIG. 22-4 Attachment of the anterior cruciate ligament (ACL) on the femur. The dotted lines show the attachment of the main fibers of the ACL. When we drew a vertical line (VL) through the contact point (C) between the femoral condyle and the tibial plateau on a picture taken at 90 degrees of flexion, this line and the long axis of the ACL attachment (AX) was crossed at the point (PL) on the vertical line 5 to 8 mm anterior to the edge of the joint cartilage. The center (AM) of the attachment of the anteromedial bundle was located at the point 5 to 6 mm distal from the back of the femur as measured using the offset guide. AFS, A parallel line with an axis of the femoral shaft.

150

the imaginary vertical line (see Fig. 22-4). The femoral tunnel that has been created already for the AMB reconstruction can be used as a good landmark to determine the center of the attachment of the PLB. To insert a guidewire at this point, the surgeon manually holds a Kirschner wire and aims it at the center of the attachment of the PLB on the femur through the tibial tunnel, keeping the femur horizontal at 90 degrees of knee flexion. Then the surgeon lightly hammers the wire into this point and drills it (Fig. 22-5, A). A 4.5-mm diameter tunnel is drilled using this wire as a guide. Our cadaveric study showed that this technique provides some benefits for Endobutton fixation, including easy passage of the graft and easy flip of an Endobutton.4 The tunnel length is measured in the same manner. Finally, two sockets are created for the AMB and PLB reconstruction with cannulated drills in the Endobutton fixation system (Acufex Microsurgical, Mansfield, MA), the diameter of which is matched to the two grafts prepared with the technique described in the following section. Thus, two tunnels are created inside the ACL remnant on the lateral condyle (Fig. 22-5, B). The different directions of the two pairs of tunnels are demonstrated by inserting two wires through the tibial tunnel to the femoral tunnel at 90 degrees of knee flexion (Fig. 22-5, C).

Graft Fashioning The harvested semitendinosus is cut in half. Regarding the gracilis tendon, both ends are resected so that the thickest portion is used for the graft, and the length is matched to half the length of the semitendinosus tendon. One-half of the semitendinosus tendon and the resected gracilis tendon are doubled and used for AMB reconstruction. The remaining half of the semitendinosus tendon is also doubled and used for the PLB reconstruction. Using these tendon materials, the hybrid grafts are fashioned (Fig. 22-6). At the looped end of each doubled tendon graft, an EndobuttonCL (Acufex Microsurgical, Mansfield, MA) is attached. The length of the Endobutton-CL is determined such that a 15- to 20-mm long tendon portion can be placed within the bone tunnel. A commercially available polyester tape (Leeds-Keio Artificial Ligament, Neoligament, Leeds, United Kingdom) is mechanically connected in series with the other end of the doubled tendons, using the original technique5 (see Fig. 22-6). This tape is strong, soft, meshed, 10 mm wide, and 15 cm long. In our experience, the diameter of the tendon portion ranges from 6 to 8 mm for the AMB graft and from 5 to 6 mm for the PLB graft. The first advantage of the hybrid graft is that it is stronger and stiffer than the tendon-suture composite.12,13 The second advantage is that the tape portions of the two grafts can be simultaneously fixed to the tibia with an initial tension.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

22

FIG. 22-5 Insertion of a guidewire for the posterolateral bundle (PLB) into the femur using the transtibial tunnel technique (observed through the medial portal). A, First, a surgeon drills a Kirschner wire into the center of the PLB attachment on the femur. B, Two tunnels are independently created within the anterior cruciate ligament (ACL) remnant on the lateral condyle. C, Each wire is inserted through a tibial tunnel to a femoral tunnel at 90 degrees of knee flexion demonstrates the position and direction of a pair of tunnels. Note that the directions of the anteromedial bundle (A) and PLB (P) wires are different.

The latter feature is specifically important for anatomical double-bundle reconstruction.

Graft Placement The graft for the PLB reconstruction is introduced through the tibial tunnel to the femoral tunnel using a passing pin

and is fixed on the femur by an Endobutton. Then the graft for the AMB is placed in the same manner. Thus, the two bundles having different directions are intraarticularly grafted (Fig. 22-7). The grafts rarely impinge to the femur. Notchplasty is performed only in knees with an extremely narrow notch due to osteochondral spar formation or a similar problem. 151

Anterior Cruciate Ligament Reconstruction

FIG. 22-6 The hybrid grafts. At the looped end of each doubled tendon graft, an Endobutton-CL is attached. A polyester tape is mechanically connected in series with the other end of the doubled tendons, using the original technique. An absorbable suture marker is attached to each graft to show the point of flip of the Endobutton. The diameter of this tendon portion shows 7 to 8 mm for the anteromedial bundle (AMB) graft and 5 to 6 mm for the posterolateral bundle (PLB) graft.

FIG. 22-7 The reconstructed two bundles as observed through the lateral portal. The posterolateral bundle (P) is observed behind the anteromedial bundle (A).

Graft Tensioning and Fixation For graft fixation, the knee is flexed to 10 degrees with a sterilized thin pillow placed beneath the thigh, keeping the heel in contact with the operating table (Fig. 22-8). A spring tensiometer (Meira, Nagoya, Japan) is attached at each end of the polyester tape portion of the graft. An assistant surgeon simultaneously applies tension of 30N to each graft for 2 minutes at 10 degrees of knee flexion, and a surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples in the turn-buckle fashion.5 152

FIG. 22-8 A surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples, applying a 30N tension to each graft for 2 minutes using tensiometers (TM) at 10 degrees of knee flexion.

The mechanism of our tensioning technique is explained as follows14: According to our in vivo measurement studies, when we applied the same initial tension on each bundle at 10 degrees of knee flexion, each tension pattern was similar to that of the normal bundle. This fact suggested that the slight flexion position (10 degrees of knee flexion) is recommended as the most appropriate knee flexion angle for easy graft tensioning. On the other hand, the full extension position may be clinically recommended to avoid flexion contracture of the knee after surgery. However, our previous studies13,15 showed that the initial graft tension in the hamstring tendon graft was dramatically reduced in the early phase after surgery. Therefore, the slight flexion position is again recommended as the most appropriate knee flexion angle for graft tensioning, when we take into account the postoperative graft relaxation. Another important question about graft tensioning is whether we should separately fix the two grafts at different flexion angles. According to our in vivo measurement studies, if we apply a tension to the AMB after fixing the PLB at the extension position, the initial tension applied to the PLB is reduced to an unknown degree. A surgeon cannot sufficiently control the graft tension in this technique. Therefore, in anatomical double-bundle ACL reconstruction, it is important to simultaneously fix the two bundles, applying appropriate initial tensions to the two grafts. Postoperative 3D computed tomography shows that each tunnel outlet was created at the center of the anatomical attachment of the AMB or the PLB (Fig. 22-9).

CLINICAL RESULTS A prospective comparative cohort study was carried out with 72 consecutive patients with chronic ACL deficiency to compare three ACL reconstruction procedures using

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

22

FIG. 22-9 Postoperative three-dimensional computed tomography showing that each tunnel outlet was created at the center of the anatomical attachment of the anteromedial bundle (A) or the posterolateral bundle (P).

hamstring tendon grafts.6 The first 24 patients underwent a single-bundle procedure using a six-strand hamstring tendon graft. The next 24 patients underwent a nonanatomical double-bundle procedure using four-strand and two-strand hamstring tendon grafts. The final 24 patients underwent the anatomical double-bundle procedure using the same four-strand and two-strand hamstring tendon grafts. All 72 patients underwent postoperative management with the same rehabilitation protocol.6 There were no significant differences among the background factors. The postoperative anterior laxity measured with the KT-2000 was significantly less after the anatomical double-bundle reconstruction than after the single-bundle reconstruction. Concerning the results of the pivot-shift test, the anatomical double-bundle reconstruction was significantly better than the singlebundle reconstruction, although this test was not an objective evaluation (Table 22-1). In the International Knee Documentation Committee (IKDC) evaluation, the anatomical double-bundle reconstruction clinically tended to be superior to the single-bundle reconstruction, although no statistical significance could be calculated. There were no significant differences in the range of knee motion and the muscle torque. Thus, this study demonstrated that the anatomical double-bundle ACL reconstruction with the hamstring tendons was clinically useful in the treatment for the ACL deficient knee. In addition, this study also showed that in ACL reconstruction with the hamstring tendons, the anatomical double-bundle procedure was superior to the single-bundle procedure, at least in terms of restoration of the anterior and rotational knee stability as measured with the KT-2000 and pivot-shift examinations. We should consider reasons why the results concerning knee stability are superior in the anatomical double-bundle reconstruction in our clinical study compared

with the single-bundle reconstruction. Yagi et al16 reported that anatomical double-bundle reconstruction restores knee kinematics closer to normal than does single-bundle reconstruction. Namely, under a 134N anterior tibial load, anterior tibial translation for the anatomical reconstruction was significantly similar to that of the intact knee than was the single-bundle reconstruction. The in situ force in the ACL reconstructed with the anatomical double-bundle procedure averaged 97% of that in the normal ACL, whereas the force in the ACL reconstructed with the single-bundle procedure averaged only 89%. Therefore we can make the following speculations: First, the reconstructed PLB as well as the reconstructed AMB may be effective to reduce the anterior translation of the tibia in the range of less than 30 degrees. Second, excessively overloading to one bundle can be avoided during the remodeling phase, resulting in good maturation of not only the PLB graft but also the AMB graft. The good maturation of the AMB graft might result in the reduction of the anterior tibial translation at 90 degrees as well as 30 degrees. Third, the graft surface area of the two thin tendon grafts used in the anatomical procedure was greater than the area of the one thick graft used in the single-bundle procedure. Therefore, concerning graft anchoring and revascularization, the two thin bundles in the double-bundle reconstruction may be superior to the one thick bundle in the single-bundle reconstruction, resulting in the reduction of the anterior tibial translation at 30 and 90 degrees of knee flexion. Thus, there is a high possibility that the anatomical double-bundle ACL reconstruction with the hamstring tendons is clinically useful in the treatment for the ACL deficient knee. However, there are some limitations in our clinical study.6 To establish the clinical utility of the anatomical double-bundle ACL reconstruction for the ACL deficient knee, further clinical studies are needed concerning the 153

Anterior Cruciate Ligament Reconstruction TABLE 22-1 Clinical Results in the Postoperative Evaluation Single Bundle

Nonanatomical

Anatomical

Double Bundle

Double Bundle

Loss of knee

1 patient

2 patients

1 patient

0

0

1

(
)

12 patients

16 patients

21 patients

(þ)

9 patients

5 patients

3 patients

(þþ)

3 patients

3 patients

0 patients

2.8  1.9

2.2  1.5

1.1  0.9

<2 mm

13 patients

17 patients

22 patients

3–5 mm

9 patients

4 patients

2 patients

>5 mm

2 patients

3 patients

0 patients

flexion (<10 degrees) Loss of knee extension Pivot-shift test

Side-to-side anterior laxity

IKDC evaluation (points) A

10 patients

11 patients

16 patients

B

12 patients

11 patients

8 patients

C

2 patients

2 patients

0 patients

D

0 patients

0 patients

0 patients

effects on rotatory stability, long-term survival of the graft functions, and comparisons with other procedures involving reconstruction with the bone–tendon–bone graft.

References 1. Kurosawa H, Yamakoshi K, Yasuda K, et al. Simultaneous measurement of changes in length of the cruciate ligaments during knee motion. Clin Orthop 1991;265:233–240.

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2. Amis AA, Dawkins GPC. Functional anatomy of the anterior cruciate ligament. Fiber bundle actions related to ligament replacement and injuries. J Bone Joint Surg 1991;73B:260–267. 3. Back JM, Hull ML, Patterson HA. Direct measurement of strain in the posterolateral bundle of the anterior cruciate ligament. J Biomechanics 1997;30:281–283. 4. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Anatomic and clinical studies. Arthroscopy 2004;20:1015–1025. 5. Yasuda K, Kondo E, Ichiyama H, et al. Surgical and biomechanical concept of anatomic anterior cruciate ligament reconstruction. Oper Tech Orthop 2005;25:96–102. 6. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic double-bundle reconstruction of the anterior cruciate ligament. Comparisons with non-anatomic single- and double-bundle reconstructions. Arthroscopy 2006;22:240–251. 7. Yasuda K, Tsujino J, Ohkoshi Y, et al. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med 1995;23:706–714. 8. Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Autogenous doubled hamstring tendons connected in series with polyester tapes. Am J Sports Med 1997;25:99–106. 9. Girgis FG, Marshall JL, Monajem ARS. The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis. Clin Orthop 1975;106:216–231. 10. Dodds JA, Arnoczky SP. Anatomy of the anterior cruciate ligament: a blueprint for repair and reconstruction. Arthroscopy 1994;10: 132–139. 11. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 12. Miyata K, Yasuda K, Kondo E, et al. Biomechanical comparisons of anterior cruciate ligament reconstruction procedures with flexor tendon graft. J Orthop Sci 2000;5:585–592. 13. Yamanaka M, Yasuda K, Nakano H, et al. The effect of cyclic displacement upon the biomechanical characteristics of anterior cruciate ligament reconstructions. Am J Sports Med 1999;27:772–777. 14. Yasuda K. Author reply to “Letter to editor” on “Anatomical reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Anatomical and clinical studies.” Arthroscopy 2005;21:639–640. 15. Numazaki H, Tohyama H, Yasuda K, et al. The effect of initial graft tension on mechanical behaviors of the femur-graft-tibia complex with anterior cruciate ligament reconstruction during cyclic loading. Am J Sports Med 2002;30:800–805. 16. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666.

Anatomical Anterior Cruciate Ligament Reconstruction with Double-Bundle, Double-Stranded Hamstring Autografts: A Four-Tunnel Technique INTRODUCTION Anterior cruciate ligament (ACL) reconstruction is now commonly performed, and the procedure has become progressively more reliable as our understanding of the ligament’s anatomy and biomechanics has improved. Correct tunnel placement, sturdy grafts, and rigid fixation techniques all contribute to a good postoperative outcome, but the contemporary literature reveals that success rates following single-bundle ACL reconstruction vary between 69% and 95%.1–3 Moreover, the persistence of a pivot “glide” (International Knee Documentation Committee Grade B) in 15% of cases4 has raised doubts as to whether subsequent arthrosis can be prevented. Single-bundle ACL reconstruction techniques do not completely reproduce the native anatomy and function. Grafts behave similarly to the anteromedial (AM) bundle of the ACL, resulting in anterior tibial translation not being fully controlled toward extension,5 where the posterolateral (PL) bundle has been shown to have a more important action. Several studies using different measurement techniques have also shown that single-bundle grafts are even less efficacious in providing rotatory stability.6–8 A number of authors have proposed reconstructing both AM and PL bundles to address these issues. Zaricznyj9 first published early clinical results of this type of procedure in 1987, but Japanese researchers were instrumental in subsequently developing “double-bundle reconstruction.” Combined with a strong European interest

in the technique, several papers have since been published.10–27 These have described numerous technical variations using either one or two tibial or femoral tunnels, either autograft or allograft, and using different graft tensioning methods. This chapter describes a double-bundle ACL reconstruction technique that uses two independent tibial and two independent femoral tunnels. This was first described by Franceschi et al16 in 2002 and subsequently refined.17,20

23 CHAPTER

Pascal Christel Philippe Colombet James Robinson Jean Pierre Franceschi Patrick Djian Abdou Sbihi Guy Bellier

SURGICAL PROCEDURE Surgical Setup The patient is placed supine on the operating table. A pneumatic tourniquet is placed around the proximal thigh to allow the safe percutaneous passage of Beath needles distally. A lateral post, resting against the tourniquet, controls external rotation of the hip. The foot rests against a distal support that maintains the knee at 90 degrees of flexion. This setup allows the knee to be moved freely throughout its complete range of flexion and is essential for drilling the femoral tunnels through the AM portal.

Graft Harvesting The gracilis and semitendinosus tendons are harvested using a tendon stripper as per a routine single-bundle hamstring reconstruction. The maximal length of tendon is harvested

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Anterior Cruciate Ligament Reconstruction n 100 90 80 70 60 50 40 30 20 10 0

5

6

6 PL bundle

and the residual muscle removed. The gracilis graft (future PL bundle) is passed through a 15-mm continuous loop Endobutton-CL (Smith & Nephew, Mansfield, MA). A 20- to 30-mm Endobutton-CL is used for the semitendinosus graft (future AM bundle) due to the longer femoral AM tunnel. Each graft is then placed on a tensioning board and whipstitched with an absorbable #1 suture over 40 mm of its length. The two bundles are then calibrated. Grafts and the corresponding tunnel diameters are sized in 0.5-mm increments. The diameters of the double-stranded grafts are on average 6 mm for the PL bundle and 7 mm for the AM bundle (Fig. 23-1). If the diameter of the PL bundle graft measures less than 5 mm, we recommend attempting to triple the graft to increase its diameter. This is usually possible because the required length of the PL graft is shorter than the AM. If, however, the length is insufficient, then we recommend converting to a single-bundle technique.

Arthroscopic Reconstruction The position of the arthroscopy portals is critical to allow the correct positioning of the bone tunnels. We recommend that the AM and anterolateral portals are made just adjacent to the corresponding borders of the patella tendon. Both should be placed as high as possible, just beneath the inferior border of the patella. The high anterolateral portal allows the tibial attachment of the ACL to be well visualized in the flexed knee. We do not find it necessary to use an accessory medial portal as proposed by Yagi et al.22 Following the arthroscopic evaluation and treatment of meniscal and articular lesions, the intercondylar notch is prepared. Scar tissue and ligament remnants are cleared from the 9 to 12 o’clock positions (the 12 to 3 o’clock positions in left knees), allowing the limits of the femoral ACL footprint to be well visualized. 156

6.5

7 AM bundle

8 mm

FIG. 23-1 Distribution of graft diameters for 140 reconstructions. AM, Anteromedial; PL, posterolateral.

Preparation of the Femoral Tunnels Both femoral tunnels are drilled via the AM portal. In order to do this successfully, two critical steps must be observed. First (as described earlier), it is important that the AM tunnel is placed as midline as possible (i.e., just adjacent to the patella tendon) so that the drill does not damage the articular surface of the medial femoral condyle. Second, when placing the guidewires and during cannulated drilling, the knee should be flexed beyond 120 degrees. This is particularly important for the correct positioning of the AM femoral tunnel guidewire into the correct anatomical position “high” and “deep” (using notch navigation terminology) in the intercondylar notch. The choice to drill the femoral tunnels via the AM portal and not via a transtibial approach is based on anatomical considerations. Several authors have shown that it is difficult to place a femoral tunnel in the anatomical attachment of the ACL via the transtibial approach.28–30 The advantages of using the AM portal have been outlined by Cha et al30 and Aglietti et al,21 who found that not only can the femoral tunnel be placed more anatomically, but that the femoral and tibial tunnels can be made independent of each other and that tunnel placement is also independent of graft type. Although it is possible to drill the femoral AM tunnel via the tibial tunnel,24 it is not possible to reach the anatomical attachment of the PL bundle on the femur via this approach. In order to achieve anatomical placement of both tunnels on the femur, the alternative would be to use an “outside-in” approach.21,23 This necessitates the use of a second incision, made laterally, in order to position the drill guide. This approach is more invasive (incising both the lateral intermuscular septum and the

Anatomical Anterior Cruciate Ligament Reconstruction with Double-Bundle, Double-Stranded Hamstring Autografts: A Four-Tunnel Technique

23

Preparation of the Tibial Tunnels

FIG. 23-2 Posterolateral femoral drill guide. The round tip of the guide is introduced into the anteromedial tunnel and then rotated so that the posterolateral bundle tunnel is positioned. A 4.5-mm drill is used to pierce the posterolateral tunnel, which will be later adjusted to its final diameter.

capsule, which may be associated with some morbidity), and for this reason using the AM portal seems more appropriate. The AM femoral tunnel is made first. With the knee flexed to at least 120 degrees, a 4-mm offset femoral guide (Acufex, Smith & Nephew) is introduced through the AM portal. The 2.4-mm guidewire is placed at the 1-o’clock position in the left knee (the 11 o’clock position in the right knee). The 4.5-mm Endobutton-CL reamer is then run over the guidewire in order to pierce the lateral cortex. The tunnel is then reamed up to the corresponding graft size using the cannulated dilators. After drilling the AM tunnel, a femoral PL bundle drill guide (Fig. 23-2) is used. The appropriate size guide is introduced into the AM tunnel and then rotated so that the PL bundle tunnel is positioned lower, more shallow, and more laterally (using notch navigation terminology) in the intercondylar notch at the 2:30 position (the 9:30 position in right knees). The drill guide allows the PL tunnel to be pierced with a 4.5-mm drill (again piercing the lateral cortex) so that the two femoral tunnels diverge at 15 degrees. With the knee flexed, the AM tunnel is more vertical, measuring 45 to 50 mm in length compared with the more oblique PL tunnel, which varies between 30 and 35 mm long. The PL tunnel should breach the cortex proximal to the tibial insertion of the lateral collateral ligament such that the cortical bone is sufficient to support the Endobutton. As with the AM bundle, the PL bundle is then dilated to the appropriate diameter. The drill guide is designed so that an approximate 2-mm bony bridge is left between the tunnels as they emerge into the intercondylar notch. This corresponds to the anatomical positions of the two tunnels in the femoral ACL attachment.

The method for drilling the two tibial tunnels is based on the use of individual AM and PL bundle drill guides. The AM guide has an arm that can be hooked over the back of the retroeminence ridge (RER), which lies just anterior to the tibial attachment of the posterior cruciate ligament (PCL) (Fig. 23-3). Our anatomical studies have shown that the distance of the center of the AM bundle from the RER varies very little individually, and the guide allows a 2.4-mm wire to be reliably positioned into the center of the AM tibial bundle attachment. The wire entry point is on the proximal tibia, just medial to the tuberosity (slightly more anterior than for a routine single bundle), and is passed at 55 degrees to the horizontal. Although the position of this tunnel as it emerges into the joint is a little more anterior than for a single-bundle reconstruction, there is no risk of impingement with the roof of the notch in extension because the graft diameter is smaller and the AM bundle lies more horizontally in the notch due to the position of the femoral tunnel. After preparing the AM tunnel, the correspondingly sized PL bundle drill guide is used to prepare the second tibial tunnel. This drill guide is designed with two convergent barrels, one of which is introduced into the AM tunnel (Fig. 23-4) until it is just arthroscopically visible in the joint. The barrel has a line marked on its end that indicates the direction of the PL bundle guidewire. After rotating the handle guide so that the line points toward the native PL bundle attachment, a 2.4-mm guidewire is placed. The barrels of the guide converge so that the PL bundle wire is placed 9 mm posteriorly and laterally to the center of the AM bundle tunnel. This tunnel can then be drilled and dilated to the corresponding graft size. The PL bundle tibial tunnel lies less vertically, and the entry point is close to the anterior edge of the superficial medial collateral ligament. The two tunnels converge to leave an approximate 2-mm bony bridge between them as they emerge into the joint.

Graft Positioning, Tensioning, and Fixation A loop of strong suture material (5–0 Ticron) is then passed through the PL femoral tunnel using a Beath needle via the AM portal. A similar-strength loop (preferably of a different color) is passed through the AM femoral tunnel. The intraarticular portions of these loops are then retrieved via their corresponding tibial tunnel and are used to pull the grafts through their corresponding tunnels. The PL bundle graft (gracilis) is drawn first through its tibial and then femoral tunnels, and the Endobutton is “flipped.” 157

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40

45

50

55 60 65

FIG. 23-3 The tip of the anteromedial tibial drill guide hooks the retroeminence ridge just anterior to the posterior cruciate ligament. With the bullet oriented at 60 degrees, the anteromedial guidewire is inserted.

FIG. 23-4 The posterolateral tibial drill guide has two convergent barrels. One is introduced in the anteromedial tunnel and, after appropriate rotation, a 2.4-mm guidewire is placed.

158

The AM bundle graft (semitendinosus) is then pulled in its tunnels, and the Endobutton is similarly deployed. The distal ends of both grafts, as they emerge from the tibial tunnels, are then marked with a pen. Each graft is grasped manually and the knee is cycled throughout its full range of flexion 30 times to ensure they are adequately preconditioned with respect to their viscoelastic properties and to ensure that the Endobuttons sit flush against the femoral cortex. The AM bundle is relatively isometric, and usually there is no appreciable length change. The PL bundle, however, is anisometric, and 5 to 6 mm of length change is common. Tibial fixation is performed while 50N tension is applied to the graft via a spring dynamometer. The AM bundle is fixed at between 45 and 60 degrees using an oversize bioabsorbable interference screw. The PL bundle is then similarly fixed with an oversized bioabsorbable interference screw. The flexion angle for PL bundle fixation depends on the length change throughout knee flexion. If this is less than 3 mm, we recommend that the bundle be fixed in 20 degrees of flexion. If, however, there is greater than 4 mm variation in length, the PL bundle should be fixed close to extension. After this, the intraarticular graft positions are assessed arthroscopically to ensure that there is no notch or PCL impingement.

Anatomical Anterior Cruciate Ligament Reconstruction with Double-Bundle, Double-Stranded Hamstring Autografts: A Four-Tunnel Technique

Postoperative Care We recommend the use of an intraarticular closed suction drain to reduce the postoperative hemarthrosis. The patients may perform weight-bearing as tolerated immediately postoperatively in a hinged knee brace, allowing a protected range of motion from 0 to 60 degrees for the first 3 weeks and then 0 to 90 degrees until the brace is discarded at 6 weeks. Patients begin passive range-of-motion exercises immediately postoperatively, progressing to bicycling exercises during the first 2 postoperative months and jogging at 3 months; multidirectional activities are progressively introduced into a supervised rehabilitation program at 3 to 6 months. Return to cutting sports is allowed at 6 months.

DISCUSSION Our group began to use two-bundle reconstruction in 2001. Since then we have performed approximately 1000 procedures. In the light of this experience we have noted that two-bundle reconstruction using four tunnels appears to improve the control of rotational stability. Other authors who previously performed three-tunnel, two-bundle reconstructions (using either a single tibial tunnel with two femoral tunnels, or the inverse) have also switched to using a four-tunnel technique, having found no difference between the three-tunnel techniques compared with routine single-bundle ACL reconstruction.31–33 There is now a consensus as to the positioning of the two femoral tunnels, although the question of whether to prepare them via the AM portal18,20,22,25 or with an outside-in technique13,21,23 is still the subject of debate. These alternative methods both allow anatomical tunnel placement within the native femoral ACL attachment, using slightly differing tunnel orientations. It is also increasingly clear that a transtibial approach does not allow correct anatomical positioning of the PL bundle. However, several questions persist: What is the importance of tensioning the bundles during fixation? Should the AM bundle be tensioned to the same level as the PL bundle? In which order should the bundles be fixed? There also needs to be some consensus about the correct angle of knee flexion for the fixation of each bundle,20,34 and no results are currently available to indicate the correct tibial rotation. Authors vary with regard to their preferred graft fixation methods, with some recommending femoral interference screws. However, there are no results that would indicate superior fixation characteristics using interference screws, and the majority of authors use Endobuttons. We can state from our experience that their use does not appear to be linked to significant tunnel enlargement. Yasuda et al32

23

found similar results, with only 9% of tunnels widening following two-bundle, four-tunnel reconstruction compared with 46% using a three-tunnel, two-bundle technique and 35% for single-bundle reconstructions. We hypothesize that the lack of tunnel widening may be explained by the two separate drill holes in both the tibia and femur, which provide a larger “footprint” and improve graft healing due to an increased bone-tendon interface. Also, when individual tunnels are used for each bundle, the grafts are more likely to restrain knee kinematics in a more physiological manner compared with a two-tunnel, single-bundle graft.35 Single-bundle grafts behave as a compromise: by moving the femoral tunnel around the clock face to create a more oblique graft, there is a risk that, although rotation and translation will be better controlled toward knee extension, reduced control of translation in the flexed knee will occur. Similarly there is a tendency to position the tibial tunnel more posteriorly to avoid notch impingement, thus creating a vertical graft. Although the size of the doubled tendon grafts may be a problem, tripling or quadrupling the tendons is likely to yield a sufficiently strong graft. Zhoa et al27 published their 1-year results of a four-tunnel technique using two quadrupled hamstring grafts and found that 95.3% of patients had a normal Lachman (KT-1000 at 30 lb), 95% had a normal pivot shift, and 97.7% had a normal or nearly normal (A or B) IKDC score. The use of tibialis anterior and posterior allografts25 is another alternative that allows graft sizes of 8 to 9 mm for the AM bundle and 7 to 8 mm for the PL bundle. Although some clinical results in the literature show little improvement in the control of AP stability with twobundle, four-tunnel reconstruction,19 others have shown a tendency toward improved anterior laxity.11,26 However, it is the control of rotational kinematics that is critical; the primary disability experienced by patients with ACL rupture tends to be instability during cutting sports or turning about a weight-bearing leg, not straight anterior laxity. Unfortunately, objective assessment is still laboratory based, and an easy office method for the routine measurement of tibial rotation kinematics remains elusive.

CONCLUSION Considering the complex anatomy of the ACL and the failure of single-bundle procedures to restore rotational kinematics of the knee, we propose a more physiological reconstruction. This replaces both the AM bundle, which better restrains anterior tibial translation at greater than 45 degrees of knee flexion, and the PL bundle, which is less isometric and a more important restraint toward full extension. 159

Anterior Cruciate Ligament Reconstruction The key features of this technique are utilization of doubled or tripled hamstring tendon autografts, four independent bone tunnels (two femoral and two tibial), drilling of the femoral tunnels via the AM portal, use of original instrumentation to assist tunnel placement, and independent fixation of the two bundles at differing angles of knee flexion under controlled tension. We believe that reconstructing both bundles should provide a reconstruction that is more effective at restraining both anterior tibial translation and rotation of the tibia than is a traditional single-bundle graft.

References 1. Bach BR Jr, Tradonsky S, Bojchuk J, et al. Arthroscopically-assisted anterior cruciate ligament reconstruction using patellar tendon autograft. Five- to nine-year follow-up evaluation. Am J Sports Med 1998;26:20–29. 2. Freedman KB, D’Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a meta-analysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 3. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring in anterior cruciate ligament reconstruction: a meta-analysis. Arthroscopy 2001;17:248–257. 4. Nedeff DD, Bach BR Jr. Arthroscopic anterior cruciate ligament reconstruction using patellar tendon autografts: a comprehensive review of contemporary literature. Knee Surgery 2001;14:243–258. 5. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 6. Bull AM, Earnshaw PH, Smith A, et al. Intraoperative measurement of knee kinematics in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2002;84B:1075–1081. 7. Georgoulis AD, Papadonikolakis A, Papageorgiou CD, et al. Threedimensional tibiofemoral kinematics of the anterior cruciate ligament-deficient and reconstructed knee during walking. Am J Sports Med 2003;31:75–79. 8. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 9. Zaricznyj B. Reconstruction of the anterior cruciate ligament of the knee using a doubled tendon graft. Clin Orthop Relat Res 1987;220:162–175. 10. Rosenberg T, Brown G. Anterior cruciate ligament reconstruction with a quadrupled semitendinosus autograft. Sports Med Arthrosc Rev 1997;5:51–58. 11. Muneta T, Sekiya I, Yagishita K, et al. Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with Endobuttons: operative technique and preliminary results. Arthroscopy 1999;15:618–624. 12. Hara K, Kubo T, Suginoshita T, et al. Reconstruction of the anterior cruciate ligament using a double bundle. Arthroscopy 2000;16:860–864. 13. Pederzini L, Adriani E, Botticella C, et al. Technical note: double tibial tunnel using quadriceps tendon in anterior cruciate ligament reconstruction. Arthroscopy 2000;16:E9. 14. Hamada M, Shino K, Horibe S, et al. Single- versus bi-socket anterior cruciate ligament reconstruction using autogenous multiple-stranded hamstring tendons with Endobutton femoral fixation: a prospective study. Arthroscopy 2001;17:801–807. 15. Mae T, Shino K, Miyama T, et al. Single- versus two-femoral socket anterior cruciate ligament reconstruction technique: biomechanical analysis using a robotic simulator. Arthroscopy 2001;17:708–716.

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16. Franceschi JP, Sbihi A, Champsaur P. Arthroscopic reconstruction of the anterior cruciate ligament using double anteromedial and posterolateral bundles. Rev Chir Orthop 2002;88:691–697. 17. Bellier G, Christel P, Colombet P, et al. Double stranded hamstring graft for anterior cruciate ligament reconstruction. Arthroscopy 2004;20:890–894. 18. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20: 1015–1025. 19. Adachi N, Ochi M, Uchio Y. Reconstruction of the anterior cruciate ligament: single versus double-bundle multistranded hamstring tendons. J Bone Joint Surg 2004;86B:515–520. 20. Christel P, Franceschi JP, Sbihi A, et al. Anatomic ACL reconstruction: the French experience. Op Tech Orthop 2005;15:103–110. 21. Aglietti P, Cuomo P, Giron F, et al. Double-bundle anterior cruciate ligament reconstruction: surgical technique. Op Tech Orthop 2005;15: 111–115. 22. Yagi M, Kurunda R, Yoshiya S, et al. Anatomic anterior cruciate ligament reconstruction: the Japanese experience. Op Tech Orthop 2005;15:116–122. 23. Shino K, Nakata K, Nakamura N, et al. Anatomic anterior cruciate ligament reconstruction using double-looped hamstring tendon grafts via twin femoral and triple tibial tunnels. Op Tech Orthop 2005; 15:130–134. 24. Brucker PU, Lorenz S, Imhoff AB. Anatomic fixation in double-bundle anterior cruciate ligament reconstruction. Op Tech Orthop 2005;15:135–139. 25. Vidal AF, Brucker PU, Fu FH. Anatomic double-bundle anterior cruciate ligament reconstruction using tibialis anterior tendon allografts. Op Tech Orthop 2005;15:140–145. 26. Colombet P, Robinson J, Jambou S, et al. Two-bundle, four-tunnel anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2006;14:629–636. 27. Zhao J, Peng X, He Y, et al. Two-bundle anterior cruciate ligament reconstruction with eight-stranded hamstring tendons: four-tunnel technique. Knee 2006;13:36–41. 28. Giron F, Buzzi R, Aglietti P. Femoral tunnel position in anterior cruciate ligament reconstruction using three techniques. A cadaver study. Arthroscopy 1999;15:750–756. 29. Arnold MP, Kooloos J, van Kampen A. Single-incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9: 194–199. 30. Cha PS, Chabra A, Harner CD. Single-bundle anterior cruciate ligament reconstruction using the medial portal technique. Op Tech Orthop 2005;15:89–95. 31. Giron F, Aglietti P, Mondanelli N, et al. Single versus double bundle techniques in ACL reconstruction using a DSTG graft. Preliminary results. Proc 5th ISAKOS Congress 2005; paper 56. 32. Yasuda K, Kondo E, Ichiyama H, et al. Comparisons of clinical outcome after anterior cruciate ligament reconstruction among the onebundle procedure, the conventional two-bundle procedure, and the anatomical two-bundle procedure. Proc 5th ISAKOS Congress 2005; paper 59. 33. Mae T, Shino K, Hamada M, et al. Comparison of “anatomical” twobundle ACL reconstruction and Rosenberg’s bi-socket one using autogenous hamstring tendons in laxity-matched initial graft tension. Proc 5th ISAKOS Congress 2005; paper 162. 34. Miura K, Woo S L-Y, Brinkley R, et al. Determination of suitable knee flexion angles for graft fixation in double bundle ACL reconstruction. Proc 5th ISAKOS Congress 2005; paper 1. 35. Ichiyama H, Yasuda K, Kondo E, et al. An in vivo study on tension changes in the anteromedial and posterolateral bundles created with the anatomical two-route anterior cruciate ligament reconstruction procedure. Proc 5th ISAKOS Congress 2005; paper 119.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction with a Semitendinosus Hamstring Tendon Graft INTRODUCTION Anterior cruciate ligament (ACL) reconstruction is one of the most frequently performed knee surgical procedures today. Through the years, the various technical modifications together with the introduction of better instrumentations have led to the improved outcome currently reported in the various orthopaedic literature. Conventional techniques of reconstructing the torn ACL employ the use of either a bone–patellar tendon or hamstring graft. The majority of these reconstruction techniques, however, basically reconstructs the anteromedial (AM) bundle of the cruciates as the femoral tunnel is placed between the 10- and 11-o’clock position for the right knee (or 1- and 2-o’clock position for the left knee). Although good results have been generally demonstrated concurrent with its ability to restore the knee’s anteroposterior (AP) stability, questions remain regarding its efficiency in restoring rotational stability.1 Recently, the performance of an anatomical double-bundle reconstruction technique has generated renewed interests as several in vitro analyses demonstrated better results in terms of restoring knee rotational stability.2–8 Performing an anatomical double-bundle reconstruction usually entails the use of both the semitendinosus (ST) and gracilis (Gr) autografts, requiring the use of independent femoral and tibial fixations.5,9,10 With this technique, therefore, the surgery becomes more costly with the additional fixation required. Moreover,

with the use of both the ST/Gr, hamstring strength deficits can become apparent, as has been demonstrated by previous studies.3,4,11 This section illustrates a modification of the anatomical double-bundle technique using a single ST autograft with independent femoral but single tibial fixation system. This doublebundle, single-tendon (DBST) technique enables the surgeon to achieve an anatomical reconstruction without compromising the hamstring function while at the same time avoiding the use of additional fixations limiting the cost of the surgery.

24 CHAPTER

Alberto Gobbi Ramces Francisco

ANATOMY OF THE ANTERIOR CRUCIATE LIGAMENT Anatomical studies have shown that the ACL consists of two functional bundles, the AM and the posterolateral (PL) bundle, whose nomenclature is related to their insertion in the tibial plateau.1,12 These two bundles are already identifiable between the 16th to 22nd weeks of fetal development. Analyzing the insertions of these two bundles reveals that they do not lie on the same coronal plane; the AM bundle originates more proximally than the PL bundle. Biomechanically, the AM bundle tightens in flexion while the PL bundle slackens. On the other hand, the PL bundle tightens in extension while the AM bundle loosens.1,13 The ACL attaches to the femur and tibia as a collection of fascicles that fan out as they approach their insertions sites.

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SCIENTIFIC RATIONALE Early cadaveric investigations performed by Radford and Amis1 demonstrated the superior AP knee stability achieved through various ranges of flexion with a double-bundle reconstruction compared with single-bundle ACL reconstruction. Their investigation, however, did not include tests for rotational stability. Yamamoto et al,14 on the other hand, reported no significant differences between double-bundle and single-bundle ACL reconstruction of the PL bundle in terms of response to rotatory loads. However, single PL bundle reconstruction was found to be associated with increased anterior tibial translation with application of anterior loads. A more recent cadaveric study emphasized that single-bundle ACL reconstruction is mostly successful in restoring AP knee stability but is inadequate in controlling the combined rotatory loads of internal tibial torque and valgus torque. In a biomechanical study by Yagi et al6 restoration of the knee kinematics, particularly in terms of rotational control, was also demonstrated to be better with a doublebundle versus single-bundle reconstruction technique. Further in vivo studies by Tashman et al5 also revealed that single-bundle reconstruction sufficiently restores AP tibial translation but failed to provide rotational stability during dynamic loading. In general, the available studies thus far have demonstrated that single-bundle ACL reconstruction can only partially restore the normal knee kinematics because it limits anterior translation but is unable to control pivot shift. In addition, biomechanical analysis of an anatomically reconstructed knee also demonstrated that anterior tibial translation for double-bundle reconstruction is significantly closer to that of an intact knee and produces better rotatory stability.7,8

SURGICAL TECHNIQUE Following the administration of either a spinal or general anesthesia, the patient is positioned supine on the operating table. A tourniquet is placed at the proximal aspect of the thigh with sufficient distance from the expected exit point of the Beath needle in the thigh’s lateral aspect. A lateral post for thigh support and a foot bar are then placed to enable the knee to be positioned at 90 degrees of flexion on the table during surgery. This set-up also allows sufficient provision for full range of motion (Fig. 24-1). Once standard prepping and draping are completed, the tourniquet is inflated to 300 mmHg. A 3-cm vertical incision is then made, centered approximately 5 cm below the medial joint line, midway between the tibial tubercle (Gerdy’s tubercle) and the posteromedial (PM) aspect of the tibia. The sartorial fascia is incised, and the ST tendon is dissected. The tendon is completely detached from its proximal attachment with an open tendon stripper. On its tibial end, the tendon’s length is maximized, preserving as much length as possible by detaching the ST close to the bone. Ideally, a length of more than 28 cm is desired.

Preparation of the Double-Bundle Semitendinosus Graft At the back table, while the surgeon prepares the tunnels, the surgical assistant proceeds with the preparation of the doublebundle graft. Once the graft is cleaned and devoid of excess tissues, measurement of the tendon follows. The minimum length needed is 28 cm to allow the possibility of cutting the graft in half, with sufficient length to fold each half of the graft to a length of 7 cm. In such a way, we can have 2 cm of graft length for the femoral and tibial tunnels and 3 cm intraarticularly. The ends of the grafts are then whipstitched using

FIG. 24-1 A, The femoral posterolateral (PL) tunnel guide with a customized arm capable of reaching either the 9-o’clock or 3-o’clock position for anatomical placement of the PL tunnel. B, Outside-in technique for preparing the PL tunnel. C, Arthroscopic view of the guide pin as it emerges on the medial wall of the lateral condyle where the PL tunnel would be positioned.

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Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction with a Semitendinosus Hamstring Tendon Graft Ticron #5 sutures. The appropriate sizes of the EndobuttonCL (Smith & Nephew Endoscopy, Andover, MA), as determined by the AM and PL tunnel lengths, are then attached at the end of each graft. The diameter of each bundle is then measured using 0.5-mm increment sizers to match the size of the femoral and tibial tunnels. Pretensioning and preconditioning of the grafts with cyclical flexion and extension of the knee under maximal manual tension follow.15,16

Arthroscopic Anterior Cruciate Ligament Reconstruction Using standard anterolateral (AL) and AM portals, the knee joint is visualized and prepared for tunnel placements (Fig. 24-2). The anatomical footprints of the native ACL on both the femoral and tibial sides are identified. The PL femoral tunnel is initially prepared using an “outside-in” technique. To properly achieve this step, a customized PL tunnel guide is used. This customized guide has a component arm designed to reach either the 9- or 3-o’clock position. The arm of the PL guide is inserted in the AL portal and positioned at either 9 o’clock or 3 o’clock on the medial wall of the lateral condyle while the handle is maneuvered at the area of the junction of the distal femur and lateral condyle to fix the entry point for the tunnel. A guidewire is inserted from the outside, which is followed by a 4.5-mm cannulated drill to prepare the pilot hole. Once the length of this hole is measured, a 6-mm PL tunnel with its appropriate depth is drilled. Once the PL tunnel is completed, preparation of the AM tunnel follows. The standard technique is used to prepare the 7-mm tunnel positioned at either the 11- or 1-o’clock position. At the end of these steps, two anatomically positioned divergent tunnels are achieved. Attention is then placed at the tibial tunnels. We prepare our tibial tunnels at an angle of 60 degrees with the

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entry points separated by a distance of 1 to 1.5 cm. These tunnels converge on the ligament’s footprint intraarticularly. Once the guide pins are properly positioned, the 6-mm tibial PL tunnel and the 7-mm AM tunnel are drilled accordingly. Once the femoral and tibial tunnels are completed, the 6-mm graft is placed inside the PL tunnel and locked in position with an Endobutton. This is then followed by the placement of the 7-mm graft in the AM tunnel (Fig. 24-3). The fixation of both grafts are double-checked to determine whether they are securely anchored against the femoral cortex. At this time, it is also possible to arthroscopically check the grafts for impingement. With the femoral end of the grafts securely positioned, fixation on the tibial end is achieved using a single screw-post construct. This simple construct allows fixation of the two bundles at the prescribed angles. The AM bundle is fixed at 40 to 60 degrees of flexion while the PL bundle is fixed at full extension (Fig. 24-4). Prior to wound closure, the knee is examined for range of motion and stability (Fig. 24-5). Postoperatively, radiographs are taken to check the position of the grafts, and the patient is started on a standard ACL rehabilitation regimen17 (Fig. 24-6).

PRELIMINARY RESULTS Preliminary investigations comparing the results between the first 25 cases we treated with an anatomical doublebundle ACL reconstruction demonstrated that the results are comparable with those obtained with a single-bundle quadrupled ST graft, as no significant differences were noted in terms of the standard knee scales (subjective, Lysholm, Noyes, and IKDC) used at a short-term follow-

FIG. 24-2 A, Once the tibial tunnels are done, the femoral anteromedial (AM) tunnel is prepared using the AM portal. B, A 6-mm reamer is used to complete the AM tunnel.

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FIG. 24-3 A, The posterolateral (PL) bundle demonstrated here with the attached Endobutton-CL is initially inserted. B, The anteromedial (AM) bundle is then inserted. Both bundles are checked to ensure that they are properly anchored against the cortical surface of the femur.

FIG. 24-4 A, B, Tibial fixation is achieved using a post-screw construct. The anteromedial (AM) bundle is fixed at 60 degrees of flexion while the posterolateral (PL) bundle is fixed at full extension.

FIG. 24-5 A, The grafts are then checked for impingement and stability. B, The knee is also checked for full range of motion.

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FIG. 24-6 Anteroposterior (AP) and lateral postoperative radiographs are taken to check the position of the grafts. Femoral fixation (yellow circle) is achieved with end buttons while tibial fixation (green circle) is secured with a screw.

up of 2 years. Computerized analysis of anterior knee translation, however, demonstrated slightly better results with the double-bundle reconstruction. In some instances in which second-look arthroscopy was performed within the first 3 months following reconstruction, sufficient stability with Lachman’s and rotational (internal and external) tests were documented. The graft was also observed to have complete vascularization at this stage.

OTHER APPLICATIONS Other possible applications for this technique would be the reconstruction of isolated tears of either the AM or PL bundle of the ACL. In these instances, the possibility of restoring the ligament to its original form is achieved. Furthermore, even cases previously reconstructed but with persistent instability can be revised by augmenting the in sufficient ligament with isolated reconstruction of either the AM or PL bundle. Functional recovery from such a procedure is usually fast and uneventful.

SPECIAL CONSIDERATIONS The primary concern with this DBST technique is the length of the available ST autograft. Ideally, it is preferable

to have a minimum of 70 mm of graft length to have at least 20 mm of graft in the femoral and tibial tunnels and 30 mm intraarticularly. Some surgeons, however, would prefer to have a graft length of 25 mm within the femoral tunnel, whereas others have reported successful outcomes with 15 mm of the graft in contact with the tunnels.17 In our experience using DBST reconstruction, a 20-mm length of graft within the AM and PL femoral tunnels is usually sufficient. With this length, the surgeon then has the option of using a 20- or 25-mm Endobutton-CL for the AM bundle and a 15- or 20-mm Endobutton-CL for the PL bundle, considering that the average AM tunnel length ranges between 40 and 45 mm, whereas PL tunnel length usually ranges from 35 to 40 mm. Of the two femoral tunnels needed, proper placement of the PL tunnel is the more technically demanding because it can be quite a challenge to reach the 3-o’clock (or the 9-o’clock) position with an “inside-out” technique. To avoid this problem, careful attention to anatomical landmarks must be observed in both the flexed and extended position of the knee. To facilitate drilling, an “outside-in” technique is used with the aid of a PL tunnel guide. The tip of the guide’s arm is pointed at either the 9- or 3-o’clock position on the medial wall of the lateral condyle, depending on which knee is being reconstructed. The other end of the guide is directed midway through the AP plane of the junction of the distal 165

Anterior Cruciate Ligament Reconstruction femur and the lateral condyle to create the entry point for the pilot hole of the PL tunnel, which is angulated 20 to 30 degrees from the horizontal plane. In this position, an average PL tunnel length of 35 to 40 mm can be expected. By strictly observing these measures, problems associated with tunnel positioning can be avoided. In instances where the semitendinosus tendon graft obtained is less than 28 cm, it is advisable to abandon the double-bundle reconstruction in favor of a triple ST reconstruction technique. Recently, the possibility of predicting the length of the hamstring graft prior to ACL reconstruction has been achieved by using simple anthropometric measurements. Inclusion of this computation to the preoperative evaluation of the patients would facilitate the identification of the appropriate reconstruction technique to be used.

TROUBLESHOOTING Concerns related to the performance of an anatomical double-bundle reconstruction involve the proper placement of the AM and PL tunnels. Ideally, the PL tunnel is positioned at the 3- or 9-o’clock position. To accurately do this, an “outside-in” technique should be used with a PL tunnel guide. However, other surgeons performing a double-bundle reconstruction prefer to drill the PL tunnel through an accessory AM portal. Currently, no prospective comparative studies have been made to determine which of these two techniques is better in terms of accuracy and reproducibility in preparing the PL tunnel. Another concern associated with this technique is the risk of encountering tunnel blow-out between the adjacent walls of the closely positioned tibial or femoral tunnels. Conventional ACL techniques also carry this risk when femoral tunnels are placed too posteriorly. Therefore, with the double-bundle procedure, this risk becomes more apparent as adequate distance between the two femoral and two tibial tunnels must be maintained. In our experience, a distance of at least 1 cm between the guidewires would be sufficient to maintain the integrity of the tunnels’ adjacent wall. In addition, correct orientation of the tunnels (diverging for femoral tunnels, converging for tibial tunnels) should always be observed to minimize the chances of encountering this problem. Furthermore, even if the tibial tunnels appear to be intact immediately after drilling, there is greater risk of breaking the common wall separating the AM and PL tunnels during fixation, especially when using interference screws. Therefore, to avoid this complication we prefer to use indirect fixation for the tibial end with a screw-post construct where we can anchor the two bundles at the recommended angle of fixation. 166

Other useful measures to observe when preparing the PL tunnel include maintaining the guidewire after drilling the pilot hole and tunnel. Doing otherwise would make it difficult to relocate the entry point for this tunnel from the outside when passing the nitinol loop to pull the PL bundle into the tunnel. Finally, in terms of patient positioning we prefer to have the knee positioned at 90 degrees of flexion on top of the table with the use of a lateral thigh post and a foot bar, instead of having the leg hang from the side of the table. This position offers the surgeons more room to make tunnel preparations more comfortable. At the same time, the combined position of the knee flexed at 90 degrees makes orientation easier when drilling the femoral and tibial tunnels. At present, it is obvious that several issues remain regarding the use of an anatomical double-bundle reconstruction. Some of these include the determination of the ideal means by which to measure rotational stability (computer navigation, motion analysis, or high-speed radiography) and the identification of the specific group of patients who would benefit most from a double-bundle reconstruction procedure. In the future, with the numerous clinical trials under way, we expect to see the long-term functional outcome of the double-bundle ACL reconstruction and to compare these results with the long-term outcome of conventional techniques currently used.

References 1. Radford WJ, Amis AA. Biomechanics of a double prosthetic ligament in the anterior cruciate ligament. J Bone Joint Surg Br 1990;72: 1038–1043. 2. Adachi N, Ochi M, Uchio Y, et al. Reconstruction of the anterior cruciate ligament: single versus double multistranded hamstring tendons. J Bone Joint Surg Br 2004;86:515–520. 3. Gobbi A, Francisco R. Anatomic double bundle ACL reconstruction with the semitendinosus tendon. Presented at the Multi Media Education Center of the 73rd American Academy of Orthopaedic Surgeons Annual Meeting, March 22–26, 2006, Chicago. 4. Makihara Y, Nishino A, Fukubayashi T, et al. Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles. Knee Surg Sports Traumatol Arthrosc 2006;14:310–317. 5. Tashman S, Colon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 6. Yagi M, Wong E, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2000;28:660–666. 7. Yasuda K, Koga H, Morito T, et al. A retrospective study of the midterm outcome of two-bundle anterior cruciate ligament reconstruction using quadrupled semitendinosus tendon in comparison with onebundle reconstruction. Arthroscopy 2006;22:252–258. 8. Yasuda K, Kondo E, Ichiyama H, et al. Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction procedure using hamstring tendon grafts: comparison among different procedures. Arthroscopy 2006;22:240–251.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction with a Semitendinosus Hamstring Tendon Graft 9. Hamada M, Shino K, Horibe S, et al. Single versus bi-socket anterior cruciate ligament reconstruction using autogenous multiple-stranded hamstring tendons with Endobutton femoral fixation: a prospective study. Arthroscopy 2001;17:801–807. 10. Muneta T, Sekiya I, Yagishita K, et al. Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with Endobutton: operative technique and preliminary results. Arthroscopy 1999;15:618–624. 11. Gobbi A, Domzalski K, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 12. Woo S. News in biomechanics research on ACL. Presented at the 8th International Conference on Orthopaedics, Biomechanics, and Sports Rehabilitation, Nov 19–21, 2004, Assisi, Italy.

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13. Mae T, Shino K, Matsumoto N, et al. Force sharing between two grafts in the anatomical two-bundle anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2006;6:1–5. 14. Yamamoto Y, Hsu W-H, Woo SL-Y, et al. Knee stability and graft function after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:1825–1832. 15. Chen L, Cooley V, Rosenberg T. ACL reconstruction with hamstring tendon. Orthop Clin North Am 2003;34:9–18. 16. Gobbi A, Mahajan S, Tuy B, et al. Hamstring graft tibial fixation: biomechanical properties of different linkage systems. Knee Surg Sports Traumatol Arthrosc 2002;10:330–334. 17. Rosenberg TD, Graft B. Techniques for ACL reconstruction with multitrac drill guide, Mansfield, MA, 1994, Acufex Microsurgical.

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25 CHAPTER

Anthony Buoncristiani Fotios Paul Tjoumakaris James S. Starman Freddie H. Fu

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Anatomical Double-Bundle Reconstruction of the Anterior Cruciate Ligament INTRODUCTION Anterior cruciate ligament (ACL) reconstruction remains one of the most common procedures performed by orthopaedic surgeons in the United States, with approximately 100,000 performed per year.1 ACL surgery has evolved tremendously from the original open techniques to modern procedures focusing on endoscopic reconstruction of the anteromedial (AM) bundle using a variety of graft choices and fixation techniques. However, the success of singlebundle ACL reconstruction ranges from 69% to 90%.2,3 In addition, according to Fithian et al,4 95% of patients who underwent single-bundle ACL reconstruction developed medial compartment degenerative radiographic changes after 7 years, and only 47% were able to return to their previous activity level. Because arthrosis was observed medially, it could not be attributed to the initial subluxation event, which usually results in a bone contusion or a concomitant meniscal tear involving the lateral compartment.4 Single-bundle ACL reconstruction is the “gold standard,” but some authors have noted persistent instability with functional testing of single-bundle ACL reconstruction.5,6 Thus, there is a growing trend toward a more anatomical ACL reconstruction that recreates both the AM and the posterolateral (PL) bundles. The double-bundle anatomy of the ACL was first described in 1938 by Palmer et al.7 The terminology of the AM and PL bundles are chosen according to their tibial insertions. The

tibial and femoral insertion sites of both the AM and PL bundles have been well described.8,9 The femoral origin has an oval shape, with the center of the AM bundle close to the over-the-top position and the center of the PL bundle close to the anterior and inferior cartilage margin. The femoral origin site changes as the knee is taken through an arc of motion. The two bundles are parallel with a vertical orientation when the knee in extension (i.e., the AM footprint is situated directly superior to the PL footprint). This changes to a more horizontal orientation, with the PL footprint becoming actually anterior to the AM footprint when the knee is flexed beyond 90 degrees. The changing orientation of the two bundles’ footprints as the knee is taken through an arc of motion leads to the observed crossing pattern of the independent components of the ACL. Although the two bundles are intertwined, their functional tensioning pattern is independent throughout the knee’s range of motion.10 Close to extension, the AM is moderately loose and the PL is tight. As the knee is flexed, the femoral attachment of the ACL takes a more horizontal orientation, causing the AM bundle to tighten and the PM bundle to loosen. The ACL has been described as a restraint to anterior tibial displacement and internal tibial rotation. The rotational stabilizing component might be better attributed to the PL bundle. The idea of reconstructing both bundles of the ACL was described by Mott and Zaricznyj in the 1980s.11,12 They independently described

Anatomical Double-Bundle Reconstruction of the Anterior Cruciate Ligament a double-bundle technique. Mott drilled two separate tunnels, whereas Zaricznyj used a single femoral and two tibial tunnels. Despite publishing their results, the technique did not become mainstream. Recent biomechanical evidence supports the anatomical double-bundle ACL reconstruction as more accurately recreating the natural anatomy.13,14 Both translational and coupled rotational translation were significantly less in the specimens with double-bundle ACL reconstruction. We present the senior author’s (F.H.F) technique of anatomical double-bundle ACL reconstruction with two femoral and tibial tunnels using two tibialis anterior allografts.

PREOPERATIVE CONSIDERATIONS History: Signs and Symptoms ACL injuries occur frequently in sports that involve running, jumping, and cutting movements. They can occur without contact when the foot is anchored to the playing surface— usually by way of cleats or a rubber sole—and the body rotates beyond the tolerance of the ligament as the knee buckles. Thus, it is important to ask the patient how the injury occurred and the position of the knee during the injury, which may also allude to the ACL bundle injury pattern.15 This may be associated with an audible “pop.” Asking whether the athlete was able to continue to play will give you an idea of the severity of the injury. Knee pain and a hemarthrosis are usually present acutely. A complaint of instability is also common, especially with walking downhill or down stairs.

Physical Examination Inspect and palpate for an effusion. If a large effusion is present, consider aspiration for pain relief, and inspect the aspirate for any fat globules, which would be suggestive of a fracture. Check the range of motion; if it is limited, magnetic resonance imaging (MRI) should be ordered to ensure that no displaced meniscal tear is present. The physical examination of an isolated ACL tear is usually significant for a side-to-side difference with regard to Lachman and pivot-shift maneuvers. If a discrepancy between the Lachman and pivot-shift maneuvers exists, this may signify a partial tear involving either the AM or PL bundles. The PL bundle is mainly responsible for rotational stability, and a large pivot shift will be evident if it is torn. Similarly, the AM bundle is mainly responsible for translational stability when the knee is flexed, and a large Lachman maneuver will be present if the AM bundle is torn. A KT-1000 test can also be used to confirm a side-to-side difference in anterior translation. A more prominent anterior drawer

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compared with a Lachman test should alert the examiner to consider a concomitant posteromedial or posterior horn medial meniscal injury. Varus/valgus instability testing should be performed to ensure no collateral injury is present. Dial testing and posterolateral drawer testing at 30 degrees should be performed to assess for a posterolateral knee injury. Gait analysis should be performed to inspect for any underlying varus laxity. Tests for possible meniscal pathology should also be performed (i.e., joint line tenderness, McMurray maneuver), but it may be difficult to distinguish between a lateral meniscal tear and a bone contusion acutely. Thus, appropriate imaging is important.

Imaging A complete knee series consisting of weight-bearing anteroposterior and notch, lateral, and patellofemoral sunrise views should be obtained. The soft tissues can be inspected for an effusion. The bony anatomy should be inspected for any fractures or subtle signs of a rotational injury, such as segond or reverse segond capsular lesion. In addition, the status of the physes and any arthritic changes should be noted. Long cassette films should be obtained for any patient with varus alignment on examination or if any arthritic changes are noted on the knee series obtained. This will help determine whether an osteotomy should be performed. An MRI is essential not only to confirm an ACL injury but, more importantly, to assess for any concomitant ligamentous or cartilage injuries that will affect the operative plan. The PL bundle is more easily visualized on coronal sectioning. Specifically, it may be seen at the level of the first cut, which includes the PCL.

Indications The absolute indications for double-bundle ACL reconstruction are evolving. Even though single-bundle ACL reconstruction is considered the “gold standard,” the technique can be improved. Gait analysis after single-bundle reconstruction has demonstrated that rotatory instability persists.5 Furthermore, biomechanical cadaveric studies have shown that even lowering the femoral insertion site to the 3- or 9-o’clock position does not fully prevent rotatory instability.16 Clinically, as many as one-fifth of the patients do not resume preinjury activities and usually complain of vague instability symptoms that objectively correspond to a mild persistent pivot shift.17 In comparison, double-bundle ACL reconstruction does restore the rotational component in a cadaveric model.14 It has been suggested that a positive pivot shift after ACL reconstruction is correlated with the development of later osteoarthrosis.18 Perhaps with reconstruction of both the AM and PL bundles, the decreased 169

Anterior Cruciate Ligament Reconstruction rotational instability will provide improved overall knee kinematics and may prevent or slow the degenerative changes seen after single-bundle ACL reconstruction.4 A contraindication to performing the double-bundle technique is in the young athlete with open physes. Two tunnels would risk physeal arrest with subsequent malalignment and possible leg length discrepancy.

SURGICAL TECHNIQUE Anesthesia and Positioning The operative extremity is identified by the patient and initialed by a member of the surgical team. All patients undergo a preoperative femoral nerve block in the holding area by our anesthesia colleagues. The patient is then placed in a supine position and given intravenous conscious sedation. A careful exam under anesthesia is performed and recorded to document the Lachman and pivot-shift maneuvers. Again, the senior author is interested in correlating the exam with the tear pattern of the individual bundles of the ACL. A tourniquet is applied to the proximal thigh. The extremity is then secured within a circumferential leg holder placed at the level of the tourniquet. The foot of the operating table is completely retracted to permit hyperflexion of the knee, which is crucial for later placement of the PL femoral tunnel. The contralateral extremity is placed within a well-leg holder with the hip flexed approximately 90 degrees and abducted and externally rotated away from the surgical field to allow unobstructed access to the operative knee (Fig. 25-1). The leg is elevated for 5 minutes, and the tourniquet is then inflated. The knee is prepped and sterilely draped.

be approximately 12 cm for sufficient graft tissue. The grafts are trimmed to a folded diameter of 7 mm for the PL bundle and 8 mm for the AM bundle. A #2 braided suture is whipstitched up and down both ends of the graft for 3 cm. The stitch depth is alternated, and care is taken to avoid penetrating the suture and risking weakening or breaking. The graft is then passed through the closedlooped Endobutton (Smith & Nephew, Andover, MA). Two Fiberwire sutures (Arthrex, Naples, FL) (one stripped and one nonstripped for later identification) are placed within the button holes. A 2–0 absorbable suture is tied through both strands of the folded graft to secure them once the graft is passed within the closed-looped Endobutton. Each graft is marked to alert the surgeon when to engage or “flip” the Endobutton (Fig. 25-2).

Surgical Landmarks With the knee flexed approximately 45 degrees, the inferior pole of the patella is marked. The inferior extent of the lateral parapatellar portal begins at the level of the inferior pole of the patella and extends proximally for approximately 2 cm. The medial parapatellar portal begins at the level of the inferior pole of the patella and extends distally along the medial aspect of the patellar tendon for approximately 2 cm. The high placement of the portals allows the arthroscopic instruments to enter the knee above the level of the fat pad. The 11 scalpel blade is angled approximately 45 degrees to the skin and distally toward the notch to safely

Anterior Cruciate Ligament Graft Preparation Two tibialis anterior allografts are individually fashioned as a double loop. The folded length of each graft should

FIG. 25-2 Doubled-over tibialis anterior allograft with whipstitch. Anteromedial diameter, 8 mm; posterolateral diameter, 7 mm. Endobutton-CL pictured at right.

FIG. 25-1 Leg positioned to allow for range of motion between full extension and 120 degrees of flexion.

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The posterior third of the lateral meniscus is more easily viewed with the knee flexed to 90 degrees; the middle third with the knee flexed to 60 degrees; and the anterior third with the knee flexed to 30 degrees. Any meniscal pathology is addressed with either repair or débridement. The lateral femoral condylar articular surface is inspected for any defects as the knee is brought through an entire range of motion.

Specific Steps

FIG. 25-3 Arthroscopic portal placement and skin incisions. AMP, Accessory medial portal; MP, medial portal; LP, lateral portal.

enter the knee without harming the articular cartilage. A low AM accessory portal will be placed with the assistance of a spinal needle to ensure proper trajectory for the PL femoral tunnel (Fig. 25-3). The knee is flexed 90 degrees, and the 11 scalpel blade is angled upward as it enters the skin at the level of the spinal needle marking. The portal is extended proximally approximately 1 cm, avoiding injury to both the underlying meniscus and the articular cartilage.

Diagnostic Examination The knee is flexed approximately 25 degrees, and the arthroscopic trochar is placed in the lateral parapatellar portal angled toward the notch and then redirected beneath the patella. The patellofemoral joint is visualized. Any cartilage defects are addressed as needed. The arthroscope is then dropped down over the trochlea and into the notch to grossly view the ACL. The knee is then extended, and a valgus stress is applied to open the medial compartment. The entire meniscus is visualized and probed for stability. Medial meniscal tears are usually seen with chronic ACL tears. Any meniscal pathology is addressed with either repair or débridement depending on the location and character of the tear. The knee is brought through a range of motion to inspect the femoral condylar articular surface for any defects. The tibial plateau articular cartilage is also inspected for any defects. The knee is then placed in a figure-four position to view the lateral compartment. The PL bundle is best visualized in this position. The entire meniscus is once again observed and probed for stability. Lateral meniscal longitudinal tears are commonly seen with acute ACL tears at the junction of the middle and posterior thirds.

Attention is then redirected to the notch. Any obstructing fat pad or ligamentum mucosum is removed with the shaver or ArthroCare Coblation device. The bundles of the ACL are carefully dissected with a small ArthroCare Coblation device to fully appreciate the injury tear pattern. Because the two bundles are differentially tensioned depending on the position of the knee at the time of injury, the tear pattern can be quite different for each bundle.18 We are currently performing a prospective study to correlate the preoperative examination (i.e. KT-1000, examination under anesthesia [pivot-shift and Lachman maneuvers]) with the individual tear pattern of each bundle (Fig. 25-4). The remnant of the ACL bundles is then débrided from both their femoral and tibial insertions. The ArthroCare Coblation device is used to mark the AM and PL femoral and tibial footprints (Fig. 25-5). No notchplasty is performed. An 18-gauge spinal needle is directly visualized as it passes from the location of the low AM portal onto the medial face of the lateral femoral condylar notch in the region of the previously marked PL bundle (Fig. 25-6). Once satisfactory trajectory for the PL bundle with the

FIG. 25-4 Anterior cruciate ligament (ACL) tear of anteromedial (AM) and posterolateral (PL) bundles, each from femoral insertion. Preoperative exam under anesthesia demonstrated a 3þ Lachman and a 3þ pivot shift. LFC, Lateral femoral condyle.

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FIG. 25-5 Anteromedial (AM) and posterolateral (PL) tibial (A) and femoral (B and C) footprints marked. LFC, Lateral femoral condyle.

FIG. 25-6 A, B, Accessory medial portal visualization with an 18-gauge needle.

spinal needle has been determined, remove the spinal needle and make the low AM portal with an 11 scalpel blade angled upward to avoid cutting the anterior horn of the medial meniscus. Pass a 3/32-mm Steinman pin via the low AM portal onto the medial face of the lateral femoral condylar notch. Place the pin approximately 8 mm posterior to the anterior articular margin and approximately 5 mm superior to the inferior articular margin of the lateral femoral condyle. Once correct placement of the pin has been obtained, bring the knee into approximately 120 degrees of hyperflexion and tap it into place with a mallet (Fig. 25-7). Ensure that the pin did not penetrate the medial meniscus, and then slide the 7-mm acorn reamer over the Steinman pin and have it rest against the medial face of the lateral femoral condylar notch. Ream to a depth of 25 mm. Then place the Endobutton drill within the previously reamed canal, and drop your hand before starting 172

the drill, which will maximize the PL tunnel length. With the knee still flexed at 120 degrees, have your assistant place his or her hand on the lateral aspect of the knee and push the biceps tendon inferiorly, which will deflect the common peroneal nerve away from the drill trajectory. Barely perforate the lateral femoral cortex with the Endobutton drill, and quickly retract it backward to minimize the risk of injury to the common peroneal nerve. Measure the transcondylar length, and choose the appropriately sized continuously looped Endobutton. If the length is greater than 35 mm, replace the 7-mm acorn reamer within the PL tunnel and dilate the tunnel depth to 30 mm by hand. There should be at least 15 mm of graft tissue within the tunnel (Fig. 25-8). Make a 3- to 4-cm incision over the AM surface of the tibia for creation of the tibial tunnels and passage of the grafts. This is in a location midway between the tibial tubercle and the posteromedial border of the tibia. Dissect

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FIG. 25-7 A, Guide pin placement for posterolateral femoral tunnel. B, 7-mm acorn reamer as inserted from accessory medial portal. LFC, Lateral femoral condyle.

FIG. 25-8 Posterolateral (PL) femoral tunnel. LFC, Lateral femoral condyle.

the soft tissues both medially and laterally for easy access to the future tibial AM and PL tunnels. Identify the tibial PL footprint, which is located just medial to the posterior horn of the lateral meniscus and anterior to the PCL. The footprint should have been previously marked with the ArthroCare Coblation device. Place the ACL director guide (Smith & Nephew, Andover, MA) at 55 degrees with the tip centered within the PL tibial footprint (Fig. 25-9). Drill a 3/32 Steinman pin through the guide and within the joint so that a few millimeters are visible. Identify the AM tibial footprint with the ArthroCare Coblation device, which is a couple of millimeters anterior to the ideal single-bundle reconstruction location: the posterior aspect of the anterior

horn of the lateral meniscus, downward sloping side of the medial tibial eminence, and approximately 7 mm anterior to the PCL. Reset the ACL director guide to 45 degrees and place it within the previously marked AM tibial footprint (Fig. 25-10). Drill a second 3/32 Steinman pin through the guide and within the joint so that a few millimeters are visible. Note that the PL tibial guide pin is quite vertical in comparison with the AM tibial guide pin, which is quite horizontal. This pin attitude also prevents impingement within the notch because the PL tunnel is centered within the knee and the AM tunnel is horizontal. Once again, no notchplasty is necessary. The PL tibial guide pin also enters the AM surface of the tibia more posteromedially than the AM tibial guide pin, which is more lateral and centered (Fig. 25-11). Retract the skin on the tibia to allow placement of a 7-mm reamer over the PL tibial guide pin, and place a curette within the joint overlying the PL pin to protect the articular surfaces. Ream the PL tunnel, and remove debris with a shaver. Then place the 8-mm reamer over the AM tibial guide pin, and once again place a curette overlying the pin to protect the articular surfaces. Ream the AM tunnel, and remove debris with a shaver. There should be an approximately 1-cm bony bridge between the two tibial tunnels. Then direct your attention to the AM femoral footprint. Guide the AM femoral tunnel off the previously made femoral PL tunnel and not off the back wall of the notch, which is traditionally done with over-the-top femoral tunnel drill guides. Place the 3/32 Steinman pin 3 mm posterior and slightly superior to the previously drilled femoral PL tunnel. The Steinman pin can be placed transtibially via the previously drilled AM tunnel or via the low AM portal, whichever will allow the proper trajectory to 173

Anterior Cruciate Ligament Reconstruction

FIG. 25-9 A, Posterolateral (PL) tibial insertion landmarks. Anterior cruciate ligament (ACL) director guide set at 55 degrees. B, Guide pin drilling. AM, Anteromedial; Lat men, lateral meniscus; PCL, posterior cruciate ligament.

FIG. 25-10 A, Anteromedial (AM) tibial insertion landmarks, guide pin drilling. B, Anterior cruciate ligament (ACL) director guide set at 45 degrees. PL, Posterolateral.

FIG. 25-11 A, Guide pins for posterolateral (PL) and anteromedial (AM) tibial tunnels. B, External view of guide pins.

174

Anatomical Double-Bundle Reconstruction of the Anterior Cruciate Ligament be low enough within the notch (Fig. 25-12). Hyperflex the knee as the Steinman pin is then tapped into place. Then place an 8-mm acorn reamer over the pin and pass it within the joint to rest against the notch wall. Ream the AM femoral tunnel to a depth of 40 mm. Place the Endobutton drill within the AM tunnel. Your hand should be dropped as the knee is maintained in the hyperflexed position to maximize tunnel length and ensure that the anterolateral femoral cortex will be perforated to allow passage of the Beath pin distal to the tourniquet. Measure the transfemoral diameter, and choose the appropriately sized closed-looped Endobutton. Ideally, there should be at least 15 to 20 mm of graft tissue within the canal. With the knee hyperflexed, place a Beath pin via the low AM portal, through the PL femoral tunnel, and out of the skin on the lateral aspect of the knee. Once again, you want to drop your hand and push the biceps tendon inferiorly as you pass the pin to protect the common peroneal nerve from injury. Tie a long looped suture through the eyelet of the Beath pin, which is pulled intraarticularly and grasped out the tibial PL tunnel with arthroscopic suture retrievers. Place the 7-mm prepared PL allograft within the long looped suture attached to the Beath pin, and pull it through the respective tibial and femoral tunnels. Flip the Endobutton, and pull the graft to ensure proper engagement. Pass the Beath pin through the tibial and femoral AM tunnels with the knee hyperflexed to ensure the pin exits the thigh distal to the tourniquet and remains sterile. Depending on the trajectory of the tunnels, the Beath pin may first need to be passed via the low AM portal

FIG. 25-12 Anteromedial femoral guide pin landmarks. TT, Transtibial; MP, medial portal; PL, posterolateral.

25

through the AM femoral tunnel and the long looped suture pulled out through the AM tibial tunnel with arthroscopic suture retrievers. Place the 8-mm prepared AM allograft within the long looped suture attached to the Beath pin, and pull it through the respective tibial and femoral tunnels. Flip the Endobutton, and pull the graft to ensure proper engagement (Fig. 25-13). Cycle the knee through a full range of motion from approximately 0 to 120 degrees, approximately 20 to 30 times, while maintaining tension on both graft ends to remove any slack, and check the isometry. Tension the PL bundle first between 0 and 10 degrees of flexion. Then tension the AM bundle with the knee in approximately 60 degrees of flexion (Fig. 25-14). Tibial fixation is achieved with bioabsorbable interference screws, which are the same diameter as the corresponding tunnel. One staple is used as adjunctive fixation for each graft on the tibial side. Note that the reconstructed state recreates the crossing pattern of the PL and AM bundles (Fig. 25-15).

POSTOPERATIVE CONSIDERATIONS Rehabilitation Postoperatively, the patient is placed in a hinged knee brace. Full weight-bearing is allowed with the knee locked in extension. Continuous passive motion (CPM) is started immediately from 0 to 45 degrees of flexion and is increased by 10 degrees per day until the maximal obtainable flexion

FIG. 25-13 Posterolateral (PL) graft in place; anteromedial (AM) graft position represented by Fiberwire sutures in tunnel. Note that the position of the two bundles is parallel with the knee in full extension.

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Anterior Cruciate Ligament Reconstruction while playing collegiate football. The third occurred in a noncompliant patient 3 months after reconstruction when she returned to playing high-school basketball without a brace. Four patients have undergone staple removal for symptomatic hardware. To date, after 192 double-bundle ACL reconstructions, we have had no fractures and no radiographic signs of femoral condylar avascular necrosis or tunnel widening.

Results

FIG. 25-14 Anteromedial (AM) and posterolateral (PL) grafts in situ. The PL bundle is partially obscured by the AM bundle.

permitted by the CPM is achieved for 2 consecutive days. This is usually after 1 to 2 weeks. The brace is unlocked at 1 week, and crutches are maintained until quadriceps control is reestablished, typically in 4 to 6 weeks. The accelerated rehabilitation protocol described by Irrgang is implemented with return to contact sports at 6 months with a brace after successful function testing.19

Complications We have had three graft failures, all occurring after returning to sport. Two were sustained during contact injuries

Several in vivo functional biomechanical studies demonstrate that the kinematics are not completely restored with single-bundle reconstruction.5,6 Amis15 has demonstrated that even if the femoral tunnel is placed in a lower position than the traditionally described location, the kinematics are still not normal with regard to rotational stability. In contrast, Yagi et al14 published their results of double-bundle ACL reconstruction in a cadaveric model in which rotational stability was restored. Clinical results of double-bundle ACL reconstruction surgery are still evolving (Table 25-1).12,20–25 In 1987, Zaricznyj12 published the first clinical results for double-bundle ACL reconstruction. Twelve of the fourteen patients had excellent results. In 1999, Muneta et al24 published preliminary results suggesting that the double-bundle procedure showed a better trend with respect to anterior stability. In 2001, Hamada et al22 published a 2-year follow-up on 160 consecutive patients who underwent single or bisocket ACL reconstructions, demonstrating no statistical significant difference between the two techniques for IKDC, KT measurements, or thigh muscle strength. A trend for better anterior stability was observed in the

FIG. 25-15 Crossing pattern of anteromedial (AM) and posterolateral (PL) bundles. A, Parallel in extension. B, Crossed in flexion. LFC, Lateral femoral condyle.

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Anatomical Double-Bundle Reconstruction of the Anterior Cruciate Ligament

25

TABLE 25-1 Clinical Results Following Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Surgeon

Patients

Postoperative Anterior/Posterior Translation

Postoperative Pivot

Functional Outcome

Adachi

108

KT: all <3 mm side–side difference

Not reported

100% NL

Hamada

106

KT: all <3 mm side–side difference

Not reported

IKDC: 96% NL/near NL

Muneta

54

KT: 2 pts >5 mm

Not reported

Lyshom: 94.5
5.3

Yasuda

57

KT: 49 <3 mm; 8 were 3–5 mm

0: 56 pt; 1þ: 1 pt

Noyes: 47.5

Zaricznyj

14

Negative Lachman: 11 pts; 1þ Lachman: 3 pts

0: 14 pt

Marshall: 12 good/excellent; 2 fair

Aglietti (unpublished)

50

KT: all <3 mm side–side difference

0: 40 pt

IKDC: 96% NL/near NL

Yagi

20

KT average: 1.3 mm side–side difference

0: 17 pt

IKDC: 95% NL/near NL

Fu (unpublished)

192

KT average: 1.2 mm side–side difference

0: 105 pt; 1þ: 6 pt

93% NL; 6% near NL; 1% fair

NL, Normal.

double-bundle group. No assessment of rotatory stability was mentioned. Furthermore, in 2004, Adachi et al20 performed a randomized prospective study of 108 patients (55 single bundle; 53 double bundle) with an average of 32 months of follow-up (24 to 36 months). No statistically significant difference was noted with regard to knee joint stability (KT-2000) or to proprioception. There was a statistically significant difference with regard to a decreased incidence of notchplasty for the double-bundle group compared with the single-bundle group. The authors did not obtain IKDC results or assess for rotatory stability. Aglietti et al21 have an unpublished series of 75 patients (25 single bundle, 50 double bundle) that demonstrates a lower sideto-side KT difference, a lower number of patients with a postoperative pivot shift, and better IKDC functional results for patients who underwent double-bundle ACL reconstruction. In contrast, Yagi et al23 also have an unpublished series of 60 prospectively randomized patients (20 double bundle, 20 AM reconstruction, 20 PL reconstruction). At 1 year, there were no statistically significant differences regarding side-to-side KT measurements, IKDC functional results, or patients with a postoperative pivot shift. The senior author has performed a total of 186 primary double-bundle ACL reconstructions to date. The average follow-up is 12 months. The average postoperative side-to-side KT measurement difference is 1.2 mm. Six patients had a 1þ pivot shift and the remainder demonstrated no pivot. In addition, we have recently compared our double-bundle ACL reconstruction, early range-ofmotion data with a cohort of single-bundle reconstructions performed by the senior author. The comparison demonstrated with statistical significance that the double-bundle ACL reconstruction patients have consistently achieved

earlier better range of motion at 1 week, 4 weeks, and 12 weeks postoperative follow-up (Table 25-2).

CONCLUSION ACL reconstruction is one of the most common orthopaedic procedures performed in the United States. Singlebundle ACL reconstruction that is focused mainly on the AM bundle remains the “gold standard” that has enjoyed great success and returned many athletes to their sports. However, several authors have demonstrated that rotational instability persists. The goal of anatomical double-bundle ACL reconstruction is to address this issue and better restore kinematics to normal. It is hoped that this will decrease the rate of degenerative changes, but long-term clinical outcome studies are imperative. Regardless of whether a double-bundle reconstruction technique is chosen, knowledge of the underlying anatomy of the individual bundles will make one a better ACL reconstruction surgeon.

TABLE 25-2 Range of Motion Following Anatomical Double-Bundle and Single-Bundle Anterior Cruciate Ligament Reconstruction* 1 Week

4 Weeks

12 Weeks

PE

AF

PE

AF

PE

AF

Double bundle

2

41

1

5

1

2

Single bundle

3

70

3

23

2

9

All numbers are in degrees. *Noninvolved minus involved side-to-side difference in passive extension (PE) and active flexion (AF).

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References 1. Griffin LY, Agel J, Albohm MJ, et al. Non-contact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 2000;8:141–150. 2. Freedman KB, D’Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 3. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction—a meta-analysis. Arthroscopy 2001;17:248–257. 4. Fithian DC, Paxton EW, Stone ML, et al. Prospective trial of a treatment algorithm for the management of the anterior cruciate ligamentinjured knee. Am J Sports Med 2005;33:335–346. 5. Ristanis S, Stergiou N, Patras K, et al. Excessive tibial rotation during high-demand activities is not restored by anterior cruciate ligament reconstruction. Arthroscopy 2005;21:1323–1329. 6. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 7. Palmer I. On the injuries to the ligaments of the knee joint. Acta Chir Scand 1938;91:282. 8. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 9. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for reconstruction. J Bone Joint Surg Am 1985;67:257–262. 10. Gabriel MT, Wong EK, Woo SL, et al. Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads. J Orthop Res 2004;22:85–89. 11. Mott HW. Semitendinosus anatomic reconstruction for cruciate ligament insufficiency. Clin Orthop Relat Res 1983;172:90–92. 12. Zaricznyj B. Reconstruction of the anterior cruciate ligament of the knee using a doubled tendon graft. Clin Orthop Relat Res 1987;220:162–175. 13. Mae T, Shino K, Miyama T, et al. Single- versus two femoral socket anterior cruciate ligament reconstruction technique—biomechanical analysis using a robotic simulator. Arthroscopy 2001;17:708–716.

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14. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 15. Fu FH: Rupture pattern of the anteromedial and the posterolateral bundle of the anterior cruciate ligament. Personal communication. 16. Amis AA. Persistence of the mini pivot-shift after anatomically placed anterior cruciate ligament reconstruction. Clin Orthop Relat Res 2007;457:203–209. 17. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. A prospective, randomized clinical trial. J Bone Joint Surg Am 2004;86:2143–2155. 18. Jonsson H, Riklund-Ahlstrom K, Lind J. Positive pivot shift after ACL reconstruction predicts later osteoarthrosis—63 patients followed 5–9 years after surgery. Acta Orthop Scand 2004;75:594–599. 19. Irrgang JJ. Modern trends in anterior cruciate ligament rehabilitation: nonoperative and postoperative management. Clin Sports Med 1993;12:797–813. 20. Adachi N, Ochi M, Uchio Y, et al. Reconstruction of the anterior cruciate ligament—single versus double-bundle multistranded hamstring tendons. J Bone Joint Surg Br 2004;86:515–520. 21. Aglietti P. Double-bundle ACL reconstruction: single versus double incision. Personal communication. 22. Hamada M, Shino K, Horibe S, et al. Single- versus bi-socket anterior cruciate ligament reconstruction using autogenous multiple-stranded hamstring tendons with Endobutton femoral fixation: a prospective study. Arthroscopy 2001;17:801–807. 23. Yagi M, Hoshino Y, Nagamune K, et al. Prospective randomized comparison of double-bundle anatomic, single-bundle antero-medial, and postero-lateral ACL reconstructions—quantitative evaluation of the pivot shift test. In press. 24. Muneta T, Sekiya I, Yagishita K, et al. Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with Endobuttons: operative technique and preliminary results. Arthroscopy 1999;15:618–624. 25. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20: 1015–1025.

SUB PART III NOTCHPLASTY AND NAVIGATION

Notchplasty The intercondylar notch is the open space that lies between the medial and lateral femoral condyles of the distal femur and houses the substance of both the anterior and posterior cruciate ligaments. The anterior medial wall serves as the insertion point of the posterior cruciate ligament (PCL), and the posterior lateral wall serves as the insertion point of the anterior cruciate ligament (ACL). The intercondylar notch plays an important role in the incidence of ACL injuries and is an important technical factor to consider when optimizing the surgical technique of ACL reconstructions. The purpose of this chapter is to review the fundamental anatomy of the intercondylar notch, to understand its impact on both the risk of ACL injuries and the optimization of ACL reconstructions, to develop a better understanding regarding when a notchplasty is indicated and to what extent it should be performed, to review techniques and pearls in performing notchplasty, and to recognize potential complications or risks associated with notchplasty so that they can be avoided.

ANATOMY The subtle anatomy of the intercondylar notch in three dimensions plays an important role in the incidence of ACL injuries as well as in optimizing surgical techniques of notchplasty and the ultimate outcome of reconstructions. Several investigators1–5 have shown that a small notch width or a small notch width index (notch width divided by condylar width) is directly

correlated to increased risk of ACL injuries, especially in women (Fig. 26-1). A debate has surfaced that it is not a small notch width alone that leads to an increased risk of injury but rather a smaller ligament within the notch that may play a role. Shelbourne et al6 showed when reconstruction is performed with the same size of graft, regardless of notch width or gender, the success rates were similar. Anderson et al7 compared magnetic resonance imaging (MRI) of groups of male and female basketball players and found smaller ligaments in the female athletes as well as differences in notch width. Charlton et al8 found gender variations in both notch width and ACL volume in the groups they compared. Regardless of the debate, it is clear that radiographic findings of a small notch is predictive of ACL injury. In addition, the shape of the notch on an anteroposterior (AP) notch view may also play a role regarding ACL injury risk, with an A-framed notch being relatively more stenotic and leading to increased risk of injury compared with a wider and forgiving inverted U-shaped notch. It should be emphasized that no one is currently promoting prophylactic notchplasty in athletes with an intact ACL who incidentally have been found to have a small notch. While the AP perspective is clearly important when evaluating the intercondylar notch, the lateral perspective may be as or more important for preoperative planning. On a lateral radiograph, Blumensaat’s line represents the roof of the intercondylar notch. The slope (angular orientation relative to the femur),

26 CHAPTER

Mark R. Hutchinson

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Anterior Cruciate Ligament Reconstruction

FIG. 26-1 The notch width index can be measured on radiographic tunnel views or magnetic resonance imaging scans and represents the ratio of the width of the notch (dotted arrows) to the intercondylar width at the level of the popliteus indentation (large bold arrows).

position (anterior/posterior translational position relative to the central axis of the femur), and trueness (absolutely straight or curved at the ends) are highly variable among patients (Fig. 26-2). Numerous authors have demonstrated an increased risk of ACL reconstruction failure or postoperative extension loss if graft roof impingement is apparent on the lateral perspective.9,10 Howell et al10–13 have been instrumental in increasing the surgical community’s awareness of the importance of identifying potential graft roof impingement preoperatively to guide either tunnel placement or the extent of notchplasty intraoperatively. A preoperative lateral radiograph should be routinely obtained in full extension. If the slope of the roof of the notch is acute or its relative position is too posterior, either the tibial tunnel should be placed more posteriorly to avoid impingement14–16 or an aggressive roofplasty needs to be performed.16,17 Failure to recognize this impingement will lead to an increased risk of graft failure. Review of the preoperative lateral radiograph should also assess the trueness of Blumensaat’s line. Is it a straight line from front to back with sharp corners or edges at the inlet and outlet of the notch, or is it rounded at the ends with bumps or curves in the middle that may affect femoral tunnel selection? The roof of the notch is rarely perfectly flat; it usually has a slight curve at the inlet (anterior aspect of the notch) and the outlet (the over-the-back) position. Anteriorly, the gentle transitioning curve or blending of the femoral groove and femoral condyles into the articular surface prevents a sharp edge or corner cutting into the anterior aspect of the 180

ACL in full extension. Posteriorly within the notch, a change in slope occurs approximately 1 cm anterior to the true overthe-back position. This change of slope is usually located at the anterior edge of the leading aspect of the ACL insertion onto the lateral femoral condyle and has been termed the “resident’s ridge” by Clancy18 (Fig. 26-3). Preoperative or intraoperative awareness of the resident’s ridge is essential for optimal placement of the femoral tunnel and successful outcome of the reconstruction. If the change of slope is acute and mistaken for the true over-the-back position, the femoral tunnel will be placed too far anteriorly and lead to one of the most common causes of failure for ACL reconstructions. At the time of notchplasty, a prominent resident’s ridge should be taken down with a bur or osteotome to confirm optimal placement of the femoral tunnel guide and ensure proper positioning of the femoral tunnel. Finally, the true outlet of the notch or over-the-back position on the femur is frequently gently curved, making it difficult to lock in the extended tongues of the femoral guides designed to offset the tunnel position relative to the posterior cortex. This edge may need to be flattened or a preliminary concavity created at the site of the femoral tunnel to allow the guide to be properly seated.

INDICATIONS AND POTENTIAL RISKS Although some controversy exists regarding the necessity or extent of a notchplasty, a few fundamentals related to notchplasty cannot be debated. First, the space within the intercondylar notch must be adequate to avoid impingement on the ACL graft. Second sharp edges, osteophytes, spurs, or corners that could irritate the graft must be removed. Third, and probably most importantly, the femoral tunnel must be optimally positioned in the posterior quartile of the notch along the lateral femoral condyle. For most surgeons, notchplasty, at least to a minimal degree, allows for optimally arthroscopic visualization to ensure that proper tunnel placement occurs. Historically, more aggressive notchplasties were necessary to avoid roof impingement due to the relatively anteriorly placed tibial tunnels based on the original description of reconstruction by Clancy.19 Over time, aggressive notchplasties for routine ACL reconstructions have become less commonplace in favor of tibial tunnels placed onto the posterior edge of the tibial ACL footprint, which allows for less risk of impingement and minimal notchplasty. In these cases notchplasty is performed primarily to optimize visualization of the femoral tunnel placement. Devices have been developed to base the tibial tunnel off the notch roof, virtually guaranteeing the absence of impingement in full extension and potentially obviating the need for any notchplasty at all.20 In addition to primary or revision ACL reconstruction in which notchplasty is performed as an adjunct to the

Notchplasty

26

FIG. 26-2 On a lateral radiograph with the leg in full extension, Blumensaat’s line (A) (solid white arrows) represents the roof of the notch. The slope of the roof can be measured by the femoral roof angle (B) and is an important preoperative assessment for planning tibial tunnel placement. An assessment of the “trueness” of the roof of the notch (C) may also prevent intraoperative complications. Sharper inlet and outlet corners (straight arrow) allow better application of the over-the-back femoral guides but may contribute to anterior impingement. Gently sloped or curved inlet and outlet edges (curved arrows) may make it more difficult for the tongue of an over-the-back femoral guide to lock into position but protects the graft anteriorly against impingement.

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Anterior Cruciate Ligament Reconstruction

FIG. 26-3 The “resident’s ridge” is a change in the slope of the roof and lateral wall of the notch that occurs just anterior to the femoral anterior cruciate ligament (ACL) footprint. Cross-sectional view of a cadaveric femur (A) shows the resident’s ridge” (black arrow) to be just anterior to the ACL footprint (black triangles) and almost 10 mm anterior to the true over-the-back position represented by the posterior cortex of the femur and capsule (white arrow). The probe identifies a resident’s ridge on the arthroscopic view (B).

procedure, notchplasty may be indicated as the primary procedure itself. As noted previously, no one is currently recommending prophylactic notchplasties to reduce the risk of ACL injuries; however, in patients who have postoperative extension loss or arthrofibrosis, notchplasty may be the procedure of choice. Shelbourne and Johnson21 performed arthroscopic débridement of scar tissue and manipulation under anesthesia with notchplasty in this population with good success in regaining motion in selected patients. Clearly, prevention is the best treatment, and initial adequate notchplasty may help prevent future extension loss. Tonino et al and Millet et al in separate papers22,23 agree that inadequate notchplasty or space available for the ACL graft at the time of initial surgery was a common cause of arthrofibrosis, and adequate notchplasty might have prevented the complication. One might argue that notchplasty is a benign procedure and therefore an aggressive notchplasty is indicated in everyone. This may not be true. LaPrade et al24 found that aggressive notchplasty, in a canine model, led to early degenerative changes in the patellofemoral joint. Jarvela et al25 correlated their clinical findings of postoperative patellofemoral arthritis 7 years after ACL reconstruction with a large notchplasty. In contrast, Morgan et al26 failed to show abnormal pressure changes (in vitro using pressure-sensitive film) on the patellofemoral joint after notchplasty. Another potential risk of aggressive notchplasty is alteration of the biomechanical effects of the ACL reconstruction itself. Markolf et al27 showed increased graft forces, particularly 182

with the knee flexed at 90 degrees after notchplasty, and surmised that this could lead to an increased risk of graft failure. Anatomically, the ACL is meant to fill the notch and lie gently on the roof of the notch in full extension. This serves as an added buttress versus anterior displacement in addition to the tension along the fibers of the ligament itself. With aggressive notchplasty, this normal relationship may not occur.

TECHNIQUES AND AVOIDING COMPLICATIONS Preoperative planning continues to play an important role when considering the necessity and extent of notchplasty. Preoperative notch and lateral radiographs may reveal relative notch stenosis, spurs, or osteophytic overgrowth.28 These can be related to gender, genetics, degeneration, or the chronicity of the ACL injury. Nonetheless, when recognized preoperatively, it allows the surgeon to be more aggressive at the time of surgery to ensure the postoperative notch will be adequate to house the new ligament without impingement. When preoperatively evaluating the lateral view, it is very important to obtain the image with the knee in full extension, which allows careful interpretation of the slope and relative anterior/posterior position of the roof of the notch. This interpretation may indicate either a more aggressive notchplasty or the need to move the tibial tunnel more posteriorly to avoid notch roof impingement.

Notchplasty The notchplasty itself can be performed either arthroscopically or via a mini-open incision. The two primary goals are (1) to avoid impingement and graft irritation and (2) to optimize visualization for femoral tunnel placement. With the advent of central tibial tunnel placement 7 to 10 mm anterior to the PCL, it is rarely necessary to perform an aggressive notchplasty to avoid graft impingement. Proper tibial tunnel placement obviates impingement unless secondary osteophytic overgrowth has occurred due to chronicity of injury. For nonchronic reconstructions, the most important goal is adequate visualization for placement of the femoral tunnel, avoiding mistaking the resident’s ridge for the real over-theback position, and careful visualization of the posterior cortex of the femoral condyle. Currently, we use only a minimal notchplasty in virtually all of our primary reconstructions. Notchplasty begins with débridement of soft tissue and remnant ACL from within the notch and on the surface of the medial wall of the lateral femoral condyle. The shaver placed on an alternating setting is effective for removing large loose fragments, and the shaver set at high speed removes tissues adherent to the medial wall of the notch. If the remnant ACL is adherent to the PCL or remnant ACL stump and if the posterior capsule is present posteriorly in the notch, an arthroscopic biter can macerate the tissue, making it easier for the shaver to be effective. Many surgeons use thermal ablation probes to accomplish this step. Special care should be used when débriding soft tissues posterior and medial to the PCL because numerous bleeders

26

are present and one could enter the popliteal artery. In general, we avoid débriding the tissue just adjacent to the 12-o’clock position. This avoids bleeding and allows us to complete 90% of our notchplasties without a tourniquet. If bleeding is encountered, it can be controlled with arthroscopic electrocautery or by inflating the tourniquet. The ligament of Humphrey, the anterior meniscofemoral ligament, lies obliquely just anterior to the PCL and is frequently damaged at the time of soft tissue débridement or tibial tunnel reaming. There are no data that support poor outcomes secondary to the sacrifice of the ligament of Humphrey; nonetheless, it is probably best to leave it intact as a secondary rotational stabilizer if possible. Bony notchplasty usually begins anteriorly and progresses posteriorly. Arthroscopically, a subtle pink color change can be visualized at the entrance of the femoral notch where the articular surface of the lateral femoral condyle thins and curves acutely into the surface of the wall of the notch (Fig. 26-4). This subtle change is usually about 1 to 2 mm onto the articular surface and marks our initial site of anterior notchplasty. This edge can be taken down with a small osteotome or a high-speed bur/shaver (Fig. 26-5). Once the leading edge is removed, the high-speed bur/shaver is used to flatten the remaining wall to the same depth in a front-toback direction. The goal is to create a smooth flat surface that does not irritate the graft and allows direct visualization to the posterior outlet (over-the-back position) of the notch. In general, the extent of this minimal notchplasty is effective

FIG. 26-4 Arthroscopic view of the inlet of the notch revealing the presence of the posterior cruciate ligament (PCL) and absence of the anterior cruciate ligament (ACL). A, The subtle pink color change is noted where the articular cartilage of the lateral condyle transitions, becoming thin and curving into the roof of the notch (identified by spinal needle) (B). Minimal notchplasty will begin by removing this 1 to 2 mm of articular surface and working posteriorly to flatten the roof and lateral wall. In acute ACL reconstructions, it is rare to require more aggressive notchplasty to provide space for the reconstruction or visualize the true over-the-back position.

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Anterior Cruciate Ligament Reconstruction

FIG. 26-5 Initiation of notchplasty can be performed using a small osteotome (A, B) or simply by using mechanical arthroscopic devices such as an arthroscopic shaver set on high speed or an arthroscopic bur.

for visualization of the over-the-back position in most patients. Approximately, two-thirds to three-quarters of the way back, the bur frequently becomes more erratic and is difficult to maintain on the surface of the wall of the notch. This is due to a change in slope that occurs within the notch and a change in density of the bone itself. This is the resident’s ridge.18 The change in slope occurs immediately anterior to the ACL insertion onto the femur. The erratic nature of the bur is secondary to the increased cortical thickness of the ACL insertion itself. The resident’s ridge should be carefully flattened with the bur to match the entire flat surface of the wall of the notch. This will allow excellent visualization of the true over-the-back position on the femur and allow optimal placement of the femoral over-the-back guide. Indeed, at the time of notchplasty, we will usually make a small “prehole” or concavity where we expect the tunnel placement to be. This allows the over-the-back guide to slide more securely in place over the back of the lateral femoral condyle. It should be noted that leaving the cortical edge on the most posterior aspect of the notch is important during notchplasty and guide placement. Notchplasty that is too aggressive on the posterior wall of the notch can make proper positioning of the over-the-back guide difficult. Although notchplasties for primary reconstructions performed in a timely fashion are generally straightforward, notchplasties can be particularly challenging in cases of revisions, chronic reconstructions, and patients who suffered from postoperative loss of extension or arthrofibrosis. In revision cases, the previous surgeon may have débrided relative landmarks. In chronic cases, significant osteophytic overgrowth can virtually close off the entire entry into the notch 184

or can leave spurs posteriorly that throw off the over-the-back guides. Ultimately the goal in these complex cases is the same: full extension, adequate space available for the ligament, and excellent visualization for reconstructions. Technically, the surgeon must work stepwise from known to unknown and from front to back in the notch. Débridement of soft tissue is usually straightforward; however, care must be taken to avoid viable anatomical structures including previous reconstructed ligaments. If a Cyclops lesion is present (scar tissue anteriorly in the notch, frequently with an adherent fat pad), flexing and extending the knee under arthroscopic visualization may help to identify the ACL so that the surgeon can target the scar tissue itself. In some cases it may be necessary to remove even the reconstructed ligament to regain full extension. Fortunately, débridement and notchplasty in post-ACL patients with arthrofibrosis are usually successful in regaining motion and normal gait as well as returning to athletic activities.29,30 In patients with significant bony overgrowth, the surgeon should begin by carefully taking down obvious osteophytes under direct visualization and then working posteriorly. Osteophytes are usually softer than the native bone and are removed easier by the bur/shaver. In revision cases in which osteophytes may be present posteriorly, we recommend obtaining intraoperative radiographs to confirm femoral tunnel placement prior to drilling to ensure optimal position. In conclusion, knowledge of notch anatomy and technical pearls in performing an appropriate notchplasty when indicated are essential skills in routinely obtaining successful outcomes of ACL reconstructions. Currently, only minimal notchplasty is usually necessary to assist in optimizing visualization of femoral tunnel placement.

Notchplasty

References 1. Souryal TO, Moore HA, Evans JP. Bilaterality in anterior cruciate ligament injuries in athletes: associated with intercondylar notch stenosis. Am J Sports Med 1988;16:449–454. 2. Souryal TO, Freeman TR. Intercondylar notch size and anterior cruciate ligament injuries in athletes: a prospective study. Am J Sports Med 1993;21:535–539. 3. Schickendantz MS, Weiker GG. The predictive value of radiographs in the evaluation of unilateral and bilateral anterior cruciate ligament injuries. Am J Sports Med 1993;21:110–113. 4. LaPrade RF, Burnett QM. Femoral intercondylar notch stenosis and correlation to anterior cruciate ligament injuries: a prospective study. Am J Sports Med 1994;22:198–203. 5. Houseworth SW, Mauro VJ, Mellon BA, et al. The intercondylar notch in acute tears of the anterior cruciate ligament: a computer graphics study. Am J Sports Med 1987;15:221–224. 6. Shelbourne KD, Davis TT, Klootwyck TE. The relationship between intercondylar notch width of the femur and the incidence of anterior cruciate ligament tears: a prospective study. Am J Sports Med 1998;26:402–408. 7. Anderson AF, Dome DC, Gautam S, et al. Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in ACL tear rates. Am J Sports Med 2001;29:58–66. 8. Charlton WPH, St John TA, Ciccotti MG, et al. Differences in femoral notch anatomy between men and women: a magnetic resonance imaging study. Am J Sports Med 2002;30:329–333. 9. Feagin JA, Cabaud HD, Curl WW. The anterior cruciate ligament: radiographic and clinical signs of successful and unsuccessful repairs. Clin Orthop 1982;164:54–58. 10. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg 1993;75A:1044–1055. 11. Howell SM. Arthroscopic roofplasty: a method for correcting extension deficit caused by roof impingement of an anterior cruciate ligament graft. Arthroscopy 1992;8:375–379. 12. Howell SM, Barad SJ. Knee extension and its relationship to the slope of the intercondylar notch. Implications for positioning the tibial tunnel in anterior cruciate ligament reconstructions. Am J Sports Med 1995;23:288–294. 13. Howell SM, Gittins ME, Gottlieb JE, et al. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after ACL reconstruction. Am J Sports Med 2001;29:567–574. 14. Miller MD, Olszewski AD. Posterior tibial tunnel placement to avoid anterior cruciate ligament graft impingement: an in-vitro and in-vivo study. Am J Sports Med 1997;25:818–822.

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15. Morgan CD, Kalman VR, Grawl DM. Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction. Arthroscopy 1995;11:275–288. 16. Berns GS, Howell SM. Roofplasty requirements in vitro for different tibial hole placements in anterior cruciate ligament reconstruction. Am J Sports Med 1993;21:292–298. 17. Tanzere M, Lenczner E. The relationship of intercondylar notch size and content to notchplasty requirement in anterior cruciate ligament surgery. Arthroscopy 1990;6:89–93. 18. Hutchinson MR, Ash SA. Resident’s ridge: assessing the cortical thickness of the lateral wall and roof of the intercondylar notch. Arthroscopy 2003;19:931–935. 19. Clancy WG, Nelson DA, Reider B, et al. Anterior cruciate ligament reconstruction using one-third of the patellar ligament, augmented by extra-articular tendon transfers. J Bone Joint Surg 1982;64A:352–359. 20. Howell SM, Lawhorn KW. Gravity reduces the tibia when using a tibial guide that targets the intercondylar roof. Am J Sports Med 2004;32:1702–1710. 21. Shelbourne KD, Johnson GE. Outpatient surgical management of arthrofibrosis after ACL surgery. Am J Sports Med 1994;22:192–197. 22. Tonino P, Risinger RJ, Garcia M, et al. Arthrofibrosis following ACL reconstruction. In Freedman KM (ed): Complications in orthopaedics: ACL surgery, American Academy of Orthopaedic Surgeons: Rosemont, IL, 2005, pp 35–40. 23. Millet PJ, Wickiewicz TL, Warren RF. Motion loss after ligament injuries to the knee. Part 1: causes. Am J Sports Med 2001;29:664–675. 24. LaPrade RF, Terry GC, Montgomery RD, et al. The effects of aggressive notchplasty on the normal knee in dogs. Am J Sports Med 1998;26:193–200. 25. Jarvela T, Paakkala T, Kannus P, et al. The incidence of patellofemoral osteoarthritis and associated findings 7 years after ACL reconstruction using bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18–24. 26. Morgan EA, McElroy JJ, DesJardins JD, et al. The effect of intercondylar notchplasty on the patellofemoral articulation. Am J Sports Med 1996;24:843–846. 27. Markolf KL, Hame SL, Hunter M, et al. Biomechanical effects of femoral notchplasty in anterior cruciate reconstruction. Am J Sports Med 2002;30:83–89. 28. Miller MD, Olszewski AD. The appearance of roofplasties on lateral hyperextension radiographs. Am J Sports Med 1999;27:513–516. 29. Shelbourne KD, Johnson GE. Outpatient surgical management of arthrofibrosis after ACL surgery. Am J Sports Med 2006;22:192–197. 30. Watanabe BM, Howell SM. Arthroscopic findings associated with roof impingement of an anterior cruciate ligament graft. Am J Sports Med 1995;23:616–625.

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Jason Koh

Computer-Assisted Navigation for Anterior Cruciate Ligament Reconstruction Computer-assisted navigation for anterior cruciate ligament (ACL) reconstruction can increase precision in tunnel placement and also provide valuable outcome information such as rotational stability.1–8 This is accomplished by registering anatomical landmarks and tracking the location of instruments and the tibia and femur in threedimensional (3D) space on what is essentially a 3D map in the computer. Values such as the location of instruments and measures of impingement and isometry, as well as the location of the femoral and tibial tunnels, are calculated and shown to the operating surgeon in real time. Computer-assisted navigation has been demonstrated to improve accuracy and decrease laxity of the ACL reconstructed joint.5

RATIONALE Computer assistance for precision navigation has been increasingly common in everyday applications such as the global positioning system (GPS) for drivers and sailors and has spread into surgical applications such as total knee replacement, pedicle screw placement, stereotactic brain surgery, and otolaryngology. In orthopaedic surgery, computer-assisted navigation has repeatedly been demonstrated to improve accuracy of total knee replacement components, not only in reducing outliers but also in correcting consistent repeated errors made by experienced surgeons.9,10 Similarly, improved accuracy in the placement of total hip components has also been demonstrated.11 Clinical outcomes have been 186

shown to be comparable between navigated and nonnavigated groups.2,5

NEED FOR PRECISION IN TUNNEL PLACEMENT Clinical outcomes in ACL reconstructed patients are significantly related to accurate tunnel placement. Although there may not be a clear consensus on where tunnels should be placed, ample evidence exists that certain tunnel positions will result in mechanical problems with the graft and/or produce inappropriate kinematics. Multiple authors have indicated that incorrect tunnel placement can result in pain, laxity, synovitis, loss of range of motion, graft impingement, and graft failure.12–23 In longer-term follow-up, errors in tunnel placement result in an increased risk of arthritis.18 Although shorter-term studies may not demonstrate substantial differences, there remains a significant risk of arthritis following ACL reconstruction, and this is likely to related in part to tunnel placement.

CURRENT ACCURACY WITHOUT NAVIGATION Multiple authors have recommended techniques and anatomical landmarks for accurate tunnel placement; however, few studies have been performed to assess the accuracy of surgeons in reproducibly creating accurate tunnels. Part of the difficulty in assessment is the difficulty in

Computer-Assisted Navigation for Anterior Cruciate Ligament Reconstruction accurately assessing intraarticular distance with the monocular, angled arthroscope and limited ability to place measuring devices in the joint in appropriate orientation. In addition, it is difficult to assess isometry or the projection of the intercondylar notch or other sources of impingement in the knee. Clinically, accuracy of ACL reconstruction techniques can be assessed by the number of revision ACL reconstructions performed each year. Recent reports suggest that approximately 10% to 20% of all cases are revised.24,25 The vast majority of the failures are related to technical errors, specifically tunnel placement.24–26 The most common error is excessive anterior femoral tunnel placement, which can decrease rotational stability and may result in a graft that is lax in extension and tight in flexion.22,24 Among experienced surgeons, it has been noted that the tibial tunnel can be placed too far posterior in order to avoid notch impingement.2–4 This can result in posterior cruciate ligament (PCL) impingement with the knee in flexion and subsequent loss of knee flexion or strain on the graft. In addition, the graft will tend to be more vertically oriented and contribute less rotational stability.24 Several studies have been performed under various conditions to assess the accuracy of ACL tunnel placement. The Pittsburgh group evaluated tunnel placement by two experienced ACL surgeons in 20 foam knee models using standard arthroscopic guides. Actual tibial tunnel placement was a mean of 4.9 mm from the ideal tunnel site. Actual femoral tunnel placement was a mean of 4.2 mm from the ideal tunnel site. These differences were believed to be significant.6 Another study from the same group demonstrated the variability of tunnel placement by surgeons with 100 to 3500 cases of experience. Two fellows and two experienced surgeons each drilled 10 tunnels in foam knees. Tibial placement by experienced surgeon 1 varied by 2 mm; experienced surgeon 2, 3.4 mm; fellow 1, 2.1 mm; and fellow 2, 2.4 mm. On the femoral side, variability was less for experienced surgeons: experienced surgeon 1, 2.3 mm; experienced surgeon 2, 3.0 mm; fellow 1, 4.5 mm; and fellow 2, 4.1 mm. Clearly, substantial variability was observed.27 Surgeon accuracy in tunnel placement has also been evaluated in cadavers.28 In an advanced arthroscopy course, instructors placed tunnels in 24 specimens. The tunnel placement was then evaluated. Fifty percent (12/24) of the femoral tunnels and 25% (6/24) of the tibial tunnels were “unacceptable.” Similar results have been anecdotally noted by instructors at other training courses. Evaluation of tunnel placement in vivo has also been performed in several centers. Harner recently reported on a series of 30 patients in which the tibial guide pin placement was evaluated by the use of intraoperative fluoroscopy.29 Tibial pins were placed using standard arthroscopic landmarks: namely, 7 mm anterior to the PCL, the medial tibial

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eminence, the anterior horn of the lateral meniscus, and the center of the visualized ACL tibial footprint. After reviewing the pin placement, Harner believed that it was necessary to reposition the pin 43% of the time. Typically, the tendency was for the experienced ACL surgeon to place the tibial tunnel too posterior (13/14 cases). In addition, repositioning of the pin was as frequent in the last 10 cases (5/10) as in the first 10 cases (5/10). Similar results were found for a series of 24 patients in which tunnel position was evaluated postoperatively by radiographs.30 Two experienced ACL surgeons performed ACL reconstructions and recorded their perceptions of femoral and tibial tunnel placement. These were then correlated with actual tunnel placement by a blinded observer. The femoral tunnel demonstrated excellent (perfect) correlation coefficient (R2 ¼ 1) on the anteroposterior (AP) radiograph (mediallateral placement) between perceived and actual position. Good correlation (R2 ¼ 0.55) was found for the lateral radiograph (AP position). However, the ability of the surgeons to describe medial-lateral tibial tunnel position was poor (R2 ¼ 0.14), and the true AP position of the tibial tunnel had no correlation (R2 ¼ 0.07, P ¼ 0.36) to the surgeons’ perception. The authors concluded that four tunnels (12.5%) “were in very different positions than that expected by the surgeon.” Other authors have noted that radiographic analysis of tunnel placement demonstrated too-posterior placement of the tibial tunnel and a relatively vertically oriented (the 11- or 1-o’clock position) femoral tunnel using standard arthroscopic instrumentation.2,4 The evidence suggests that there is room for improvement in the accuracy of ACL tunnel placement, even among the more experienced surgeons who typically participated in these studies. Accuracy among less experienced surgeons would likely be lower.

TECHNIQUES OF COMPUTER-ASSISTED NAVIGATION Essential elements of computer-assisted navigation for ACL reconstruction include the ability to register and accurately track the relative positions of the tibia and femur as well as the intraarticular landmarks that guide correct tunnel placement. This can be accomplished by several methods, but most current solutions involve markers on rigid bodies attached to the tibia and femur with pins or screws. These are tracked intraoperatively by use of a binocular infrared camera attached to a computer that can calculate the relative position of the femur and tibia to less than 1 mm and less than 1 degree of precision1 (Fig. 27-1). Some systems require the use of preoperative computed tomography (CT) scans or intraoperative 187

Anterior Cruciate Ligament Reconstruction

FIG. 27-1 Infrared camera.

fluoroscopy (Brainlab, Westchester, IL). Other systems are “image-free,” such as the Orthopilot (Aesculap, Center Valley, PA) and do not require the use of preoperative or intraoperative radiographic imaging. Most navigation protocols follow a similar progression of registration of intraarticular and extraarticular landmarks. The following description is of the workflow of the Orthopilot Navigation System (Aesculap), which functions to record kinematic and anatomical data and calculates critical values of concern to the surgeon. The navigation camera and display screen are set up opposite to the operative side of the patient, positioned opposite the knee and next to the arthroscopy tower or screen (Fig. 27-2). The initial data screens are filled in with the basic demographic data such as the name of the patient and physician (Fig. 27-3). This is followed by the optional input of preoperative radiographic information if desired by the surgeon. Clinically in the author’s practice, this has not been found to be necessary to obtain accurate and precise results. This part of the setup may be completed by ancillary personnel prior to the initiation of the case. Following appropriate graft harvest and preparation and the preparation of the knee to drill tunnels, the tracking devices are attached to the knee. Typically, prior to the placement of the trackers, the ACL stump is removed and a notchplasty is performed if desired by the surgeon, and other intraarticular pathologies such as meniscal or chondral

Arthroscopy screen

Patient Navigation screen and camera

FIG. 27-2 Arthroscopy screen.

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Surgeon

injuries are addressed. This minimizes the potential interference of the tracking devices during preparation of the knee. The trackers for ACL reconstruction are then attached by either two Kirschner wires (K wires) (Fig. 27-4) or a screw to the tibia and femur. The Orthopilot system uses trackers that can be attached by K wire fixation to bone, unlike other systems that use a significantly larger screw, which could be a potential stress riser. The K wires are placed percutaneously through small stab incisions on the anterior tibia and medial epicondyle of the femur. This minimizes morbidity associated with the placement of the trackers. We do not recommend the placement of the femoral tracker through the quadriceps mechanism because this can cause pain and potentially quadriceps weakening. We use a “passive” rather than an “active” tracking system. This system involves using reflected light from markers rather than actively emitted light from small diodes. The advantage is less weight and no cords intraoperatively. However, it is important to keep the reflective balls clean and dry intraoperatively. Following attachment of the trackers to the femur and tibia, tibial extraarticular landmarks are registered, including the tibial tubercle, the anterior tibial crest, and the medial and lateral borders of the tibia (Fig. 27-5). This is performed by palpating the identified landmarks using a pointer with attached reflective markers and clicking a foot pedal that serves as a mouse button. This step is followed by kinematic evaluation of knee motion by recording the relative positions of the femur and tibia in full extension and flexion. Acquisition of landmarks and kinematic testing takes approximately 90 seconds. The relative motion of the femur and tibia is then assessed by the surgeon in a chosen degree of flexion, usually 30 degrees. Absolute anterior and posterior translation in millimeters is recorded. In addition, the arc of internal and external rotation is recorded (Fig. 27-6). This is a measurement that cannot be accurately obtained without this system. The values are then written to a permanent file. Of note, any screen can be recorded to the computer memory at any step in the program. At this point, the arthroscope is introduced into the knee, and the usual tibial intraarticular landmarks are identified and palpated with the pointer, similar to palpation with a probe. These include the PCL, the anterior horn of the lateral meniscus, and the medial tibial spine. Following this, the anterior margin of the intercondylar notch, the femoral ACL origin, and the posterior edge of the intercondylar notch are palpated. Of note, one of the most valuable pieces of information is a real-time measurement of the intercondylar notch length (Blumensaat’s line; Fig. 27-7). The average length is 30 mm; a measurement of 25 to 26 mm suggests that the true over-the-top position has not been reached and the proposed

Computer-Assisted Navigation for Anterior Cruciate Ligament Reconstruction

27

FIG. 27-3 Patient information screens.

position is not correct. At our institution, this has been particularly useful in providing additional feedback for residents in training. Following the acquisition of intraarticular landmarks, the tibial guide is placed as usual into the knee and placed in the proposed location for the tibial tunnel. The guide

has reflective markers attached, permitting the precise identification of the location of the tibial guide pin with respect to the PCL, the intracondylar notch, and other intraarticular and extraarticular landmarks (Fig. 27-8). This allows the surgeon to choose the appropriate coronal and sagittal angles and distance from the PCL, as well as to

FIG. 27-4 Trackers attached with K wires.

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Anterior Cruciate Ligament Reconstruction

FIG. 27-5 Extraarticular landmarks.

FIG. 27-6 Knee stability Test-Preoperative.

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Computer-Assisted Navigation for Anterior Cruciate Ligament Reconstruction

27

FIG. 27-9 Femoral tunnel guidance.

FIG. 27-7 Notch length. This is an excellent check of whether the true over-the-top position has been reached.

FIG. 27-10 Postoperative screenshot.

FIG. 27-8 Tibial tunnel guidance.

avoid impingement on the roof or wall of the intercondylar notch. Following selection and recording of the tibial tunnel, the proposed femoral tunnel location is evaluated by placing the pointer tip at the location of the femoral guide pin (Fig. 27-9). This tells the surgeon where the location of the proposed tunnel site is from the posterior femoral cortex and the location on the “clock face” (i.e., the position of the graft laterally). In addition, information is provided on the amount of isometry of the graft and where and by how many millimeters the graft will impinge on the intercondylar notch. Finally, after securing the graft, the final measurements of AP translation and internal and external rotation are obtained (Fig. 27-10).

RESULTS The results of computer-assisted navigation for ACL reconstruction have demonstrated consistent improvements in tunnel placement and clinically measured laxity. The improvements have been observed in both relatively inexperienced surgeons and surgeons who have conducted multiple ACL reconstructions. In the laboratory setting, DiGioa demonstrated improved accuracy in tunnel placement in foam knees when compared with standard manual instrumentation. This was shown first with experienced surgeons and then with novices.6 Koh reported that navigation improved the accuracy of tibial tunnel placement.2 Forty-two navigated knees demonstrated a more anatomical, slightly more anterior tibial tunnel without impingement compared with nonnavigated knees. The variability of tunnel placement was 191

Anterior Cruciate Ligament Reconstruction extremely low in both the navigated and nonnavigated knee groups. After an initial learning curve, minimal extra time was needed for the navigated knees. Eichorn reported substantially better accuracy both for inexperienced surgeons (fellows)3 and for his own4 tunnel placement. Inexperienced surgeons demonstrated extremely low variability and accurate femoral and tibial tunnel placement using navigation.3 Navigated ACL reconstructions performed by a very experienced surgeon demonstrated improved tunnel placement on the lateral wall (the 10o’clock versus the 10:30 position) and a more accurate anterior placement of the tibial tunnel (more anterior without impingement).4 A French group recently published results of navigated ACL reconstructions in patients randomized to either navigated or nonnavigated knees.5 Twenty-two nonnavigated and 26 navigated knees were compared. Nineteen of the 22 nonnavigated knees had a portion of the tibial tunnel placed anterior to the roof of the notch versus none of the navigated knees. The variability of laxity was substantially less, and less than 2 mm of laxity was seen in 96.7% of navigated knees versus 83% of nonnavigated knees. The initial additional time for use of the system was 25 minutes but with experience decreased to less than 10 minutes.

DISCUSSION ACL reconstructions performed with computer-assisted navigation have demonstrated improved accuracy in tunnel placement and improved measurements of clinically assessed laxity in patients when compared with nonnavigated knees.1–6 Following an initial learning curve of a few cases, the additional time required for this increased precision is minimal. At this time, a moderate cost is associated with the initial acquisition of the machine; however, most of the navigation systems can be used for other procedures such as joint replacement. In addition, the high cost of revision surgery may be avoided if tunnel position is more accurate. The benefits of navigation have been demonstrated both for relatively less experienced and more experienced surgeons. Less experienced surgeons typically will have less variable results in addition to improved accuracy with navigation.3 More experienced surgeons, who are often quite consistent in tunnel placement, will typically shift tunnel placement to a more anatomical position.2,4,5 Computer-assisted navigation for ACL reconstruction will provide a more precise method of accurately placing tunnels and will be likely to reduce the rate of ACL failures. In the future, accurate pinless systems (currently under development) will be able to acquire anatomical information about the knee without the user having to actively register 192

points. These systems will be able to provide valuable information to the surgeon for ligament, cartilage, and bony reconstruction.

References 1. Koh JL. Computer-assisted navigation and anterior cruciate ligament reconstruction: accuracy and outcomes. Orthopaedics 2005;10: s1283–s1287. 2. Koh JL, Koo S. Leonard J, Kodali P. ACL tunnel placement: A radiographic comparison between navigated versus manual ACL reconstruction. Orthopedics 2006;10:S122–S124. 3. Eichhorn J. Three years of experience with computer navigationassisted positioning of drilling tunnels in anterior cruciate ligament replacement (SS-67). Arthroscopy 2004;20:31–32. 4. Eichhorn J. Three years of experience with computer-assisted navigation in anterior cruciate ligament replacement. http://www. aclstudygroup.com/Powerpoint-pdf02/Eichhorn.pdf. 5. Plaweski S, Cazal J, Rosell P, Merloz P. Anterior cruciate ligament reconstruction using navigation: A comparative study on 60 patients. Am J Sports Med 2006;94:542–552. 6. Picard F, DiGioia AM, Moody J, et al. Accuracy in tunnel placement for ACL reconstruction. Comp Aid Surg 2001;6:279–289. 7. Klos TV, Habets RJ, Banks AZ, et al. Computer assistance in arthroscopic anterior cruciate ligament reconstruction. Clin Orthop 1998;354:65–69. 8. Degenhart M. Computer-navigated ACL reconstruction with the OrthoPilot. Surg Technol Int 2004;12:245–251. 9. Stulberg SD, Loan P, Sarin V. Computer-assisted navigation in total knee replacement: Results of an initial experience in thirty-five patients. J Bone Joint Surg Am 2002;84:S90–S98. 10. Berry DJ. Computer-assisted knee arthroplasty is better than a conventional jig-based technique in terms of component alignment. J Bone Joint Surg Am 2004;86:2573. 11. Parratte S, Argenson JNA. Validation and usefulness of a computerassisted cup-positioning system in total hip arthroplasty. A prospective, randomized, controlled study. J Bone Joint Surg Am 2007;89:494–499. 12. Aglietti P, Buzzi R, Giron F, et al. Arthroscopic-assisted anterior cruciate ligament reconstruction with the central third patellar tendon. A 5–8-year follow-up. Knee Surg Sports Traumatol Arthrosc 1997;5:138–144. 13. Howell SM, Clark JA, Farley TE. Serial magnetic resonance study assessing the effects of impingement on the MR image of the patellar tendon graft. Arthroscopy 1992;8:350–358. 14. Howell SM, Clark J. Tibial tunnel placement in anterior cruciate ligament reconstructions and graft impingement. Clin Orthop 1992;283:187–195. 15. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg 1993;75A:1044–1055. 16. Howell SM, Wallace MP, Hull ML, Deutsch ML. Evaluation of the single-incision arthroscopic technique for anterior cruciate ligament replacement. A study of tibial tunnel placement, intraoperative graft tension, and stability. Am J Sports Med 1999;27:284–293. 17. Ikeda H, Muneta T, Niga S, et al. The long-term effects of tibial drill hole position on the outcome of anterior cruciate ligament reconstruction. Arthroscopy 1999;15:287–291. 18. Jarvela T, Paakkala T, Jarvela K, et al. Graft placement after the anterior cruciate ligament reconstruction: A new method to evaluate the femoral and tibial placements of the graft. Knee 2001;8:219–227. 19. Khalfayan EE, Sharkey PF, Alexander AH, Bruckner JD, Bynum EB. The relationship between tunnel placement and clinical results after anterior cruciate ligament reconstruction. Am J Sports Med 1996;3:335–341.

Computer-Assisted Navigation for Anterior Cruciate Ligament Reconstruction 20. Romano VM, Graf BK, Keene JS, Lange RH. Anterior cruciate ligament reconstruction. The effect of tibial tunnel placement on range of motion. Am J Sports Med 1993;3:415–418. 21. Muneta T, Yamamoto H, Ishibashi T, et al. The effects of tibial tunnel placement and roofplasty on reconstructed anterior cruciate ligament knees. Arthroscopy 1995;1:57–62. 22. Sommer C, Friederich NF, Muller W. Improperly placed anterior cruciate ligament grafts: correlation between radiological parameters and clinical results. Knee Surg Sports Traumatol Arthrosc 2000;8:207–213. 23. Yaru NC, Daniel DM, Penner D. The effect of tibial attachment site on graft impingement in an anterior cruciate ligament reconstruction. Am J Sports Med 1992;2:217–220. 24. Allen CA, Giffin JR, Harner CD. Revision anterior cruciate ligament reconstruction. Orthop Clin N Am 2003;34:79–98. 25. AOSSM institutes multi-center revision ACL study. In Matava MJ, Boden BP (eds). AOSSM Sports Medicine Update 2005; March-April: 5.

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26. Getelman MH, Friedman MJ. Revision anterior cruciate ligament surgery. J Am Acad Orthop Surg 1999;7:189–198. 27. Burkart A, Debski RE, McMahon PJ, et al. Precision of ACL tunnel placement using traditional and robotic techniques. Comput Aided Surg 2001;6:270–278. 28. Kohn D, Beusche T, Caris J. Drill hole position in endoscopic anterior cruciate ligament reconstruction. Results on an advanced arthroscopy course. Knee Surg Sports Traumatol Arthrosc 1998;6:S13–S15. 29. Cha PS, West RV, Harner CD. The results of using intraoperative fluoroscopy for ideal tibial tunnel position during anterior cruciate ligament reconstruction. 11th ESSKA Congress, May 8, 2004. 30. Sudhahar TA, Glasgow MM, Donell ST. Comparison of expected vs. actual tunnel position in anterior cruciate ligament reconstruction. Knee 2004;11:15–18.

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Neal C. Chen Charles H. Brown, Jr.

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PART E FIXATION BIOMECHANICS

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation INTRODUCTION In 1983, Lambert1 first introduced the technique of intratunnel anterior cruciate ligament (ACL) graft fixation by securing a vascularized bone– patellar tendon–bone (BPTB) ACL graft with 6.5-mm AO cancellous screws. General acceptance of interference screw fixation of BPTB ACL grafts came about in large part due to the biomechanical study of Kurosaka et al.2 This study demonstrated that fixation of a 10-mm BPTB ACL graft in human cadaveric knees with a custom-designed, headless, 9-mm, fully threaded interference screw had superior strength and stiffness compared with fixation with a 6.5-mm AO cancellous screw, staple fixation, or sutures tied over a button.2 Because of the many biomechanical studies demonstrating superior initial fixation properties and clinical outcomes studies demonstrating a high rate of success, interference screw fixation of BPTB grafts is now considered the standard against which all ACL graft fixation techniques are compared.3,4 Based on the success of interference screw fixation of BPTB ACL grafts, Pinczewski5 in 1993 introduced the use of blunt threaded metal interference screws to fix four-strand hamstring tendon ACL grafts. This fixation technique has subsequently been extended to the use of nonmetallic bioabsorbable interference screws. Rigid initial graft fixation is critical to the success of any ACL reconstruction. Attainment of rigid initial graft fixation minimizes elongation and prevents failure at the graft attachment sites

during cyclical loading of the knee prior to biological fixation of the ACL graft. The advantages of early joint motion, early weight bearing, and closed chain exercises following ACL surgery have been well documented. However, these activities place greater demands on initial ACL graft fixation. In order to maintain joint stability and prevent the development of progressive joint laxity while the knee is being subjected to the stresses of an accelerated rehabilitation program, it is important to choose ACL graft fixation methods that provide rigid mechanical fixation from time zero until biological fixation at the graft fixation sites occurs. One of the stillunanswered questions regarding ACL graft fixation is, “How strong and stiff do the initial graft fixation methods need to be to allow use of an accelerated ACL rehabilitation program?” In the late 1960s, Morrison,6,7 using force plate and gait analysis, estimated the forces experienced by the ACL during activities of daily living to range from 27 N to 445 N. Noyes et al8 estimated that the ACL is loaded to approximately 454 N during activities of daily living. However, at the present time the forces placed on the ACL with rehabilitation exercises performed in the early postoperative period or during activities of daily living are unknown. In vitro mechanical studies have demonstrated that the initial strength and stiffness of BPTB and four-strand hamstring grafts far exceed the estimated loads on the ACL.8–10 However, compared with ACL grafts, all current ACL graft fixation methods demonstrate inferior initial

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation tensile properties.11 Therefore mechanical fixation of the ACL graft in the bone tunnels is the weak link in the early postoperative period. Consequently, initial graft fixation properties are of great relevance in determining the success of ACL reconstruction in the early postoperative period. In this chapter we will discuss some limitations of in vitro biomechanical studies and review variables that influence the tensile properties of intratunnel fixation methods for bone–tendon–bone (BTB) and soft tissue grafts. For an exhaustive review of the subject matter, the University of Tampere academic dissertations of Janne T. Nurmi and Petteri Kousa are highly recommended.

LIMITATIONS OF BIOMECHANICAL STUDIES In vitro biomechanical studies are most commonly used to evaluate initial ACL graft fixation properties.12,13 However, in vitro biomechanical studies have inherent limitations. First, the use of different research models and biomechanical testing protocols make it difficult to compare the results of one study with another. Ideally, human specimens are used for biomechanical testing; however, the material properties of cortical and cancellous bone, tendons, and ligaments can vary greatly among specimens. Because of the lack of availability of human cadaveric specimens in the age range of patients typically undergoing ACL reconstruction, specimens from older donors are often used or the same specimen is tested multiple times. As demonstrated by Brown et al,14 the use of specimens from older human donors underestimates the fixation strength of fixation devices that rely on cancellous bone for fixation strength. In this study, the initial fixation strength of BPTB grafts fixed with metal interference screws in the distal femur of bovine cadavers, young human cadavers (mean age 41 years, range 33–52 years), and elderly human cadavers (mean age 73, range 68–81 years) was compared. There was no significant difference in the failure load of the bovine (799
261 N) and young human specimens (655
186 N); however, the failure load of the elderly human specimens (382
118 N) was significantly lower than the young human and bovine specimens. Based on these findings the authors concluded that elderly human cadavers are not an appropriate model for ACL reconstruction fixation studies. Performing multiple tests in the same specimen will introduce carryover effects that may affect the fixation properties of subsequent fixation techniques after the first fixation method has been tested. Beynnon and Amis12 suggest testing male specimens younger than 65 years old and female specimens younger than 50 years old to minimize these problems. Due to the paucity of suitable human cadaveric specimens, animal models are often used. Animal models have the advantage of eliminating the potential variability

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introduced because of the large differences in bone mineral density (BMD) that exist in human specimens, and their availability eliminates the need to perform multiple tests using the same specimen. However, because of the differences in BMD and tensile properties of bone that exist between human and animal specimens, the results of biomechanical tests performed using animal models cannot be directly compared with studies performed using human specimens.15 Aerssens et al15 have shown that human female femoral specimens (age range 30– 60 years) demonstrate lower BMD and failure stress compared with specimens from dogs, pigs, cows, or sheep. In this study the pig femur came closest to matching the BMD and failure stress of the human femur. Because of the higher BMD and tensile properties of animal specimens, biomechanical tests performed in animal models tend to overestimate initial fixation properties.16,17 This is particularly true for devices such as interference screws and cross-pins that rely on cancellous bone for fixation strength. Another limitation of in vitro biomechanical studies is that they simulate the time zero period prior to biological fixation of the ACL graft. These studies fail to account for the progressive healing of the ACL graft to the bone tunnel walls, which shifts the weak link from the ACL graft–fixation–bone tunnel interface to the bone–ligament interface and eventually to the intraarticular part of the ACL graft.18 Although the healing response does not affect graft fixation properties in the early postoperative period, bony or soft tissue healing in the bone tunnels will alter graft fixation properties over time. Few studies document the time frame for healing to occur at the ACL graft fixation sites. Based on the studies of Clancy et al18 and Walton,19 it appears that the bone blocks of BTB grafts heal to the bone tunnel wall by 6 weeks. Compared with BTB grafts, soft tissue grafts take longer to heal to bone. In a dog model, Rodeo et al20 demonstrated the formation of Sharpey’s fibers connecting the periphery of a soft tissue graft to the bone tunnel wall at 6 weeks. However, mechanical fixation was not achieved until 12 weeks. Two types of biomechanical tests are commonly used to evaluate the mechanical behavior of ACL ligament fixation techniques.12,13 The first and most commonly used is the single-cycle load to failure (single LTF) test. Single LTF tests attempt to simulate the response of the graft fixation technique to a sudden mechanical overload event such as a slip or fall. The load-displacement curve can be analyzed to determine the ultimate failure load, yield load, linear stiffness, and displacement at failure. Advantages of single LTF testing are that the weak link in the fixation system can be easily identified, the mode and site of the fixation failure are well defined, and an upper limit of the strength of the graft-fixation construct is established. Because failure testing attempts to replicate traumatic loading conditions, a high rate of elongation, typically 100% per second, is used. 195

Anterior Cruciate Ligament Reconstruction The second testing method involves cyclical loading of the bone–ACL graft–fixation complex. Cyclical testing evaluates the ability of the bone–ACL graft–fixation complex to resist elongation or slippage under repetitive submaximal failure loads over time. Cyclical testing attempts to approximate the loading conditions associated with rehabilitation exercises or activities of daily living in the early postoperative period prior to biological fixation of the graft. Most commonly a load control test is performed, in which the upper and lower loads are controlled and displacement over time of the ACL graft relative to the bone is measured. By determining the distance between markers on the bone and the ACL graft at the beginning and end of the test, elongation or slippage of the ACL graft with respect to the bone can be measured. At the present time there is little agreement on the force limits or the number of cycles that should be performed, making it difficult to compare data among studies. Beynnon and Amis12 have recommended force limits between 150 N and –150 N and 1000 load cycles. One thousand cycles approximates 1 week of flexion-extension loading of the knee.13 The number of cycles is limited by the ability to keep the specimen moist during testing and the thawing of the freeze clamps that are commonly used to grip soft tissue ACL grafts. Despite these limitations, in vitro biomechanical laboratory testing can provide useful information on the performance of ACL ligament fixation techniques. In summary, single LTF testing evaluates the initial strength and stiffness of the bone–ACL graft–fixation complex, whereas cyclical testing provides information on slippage and progressive elongation at the graft fixation sites that occur as a result of rehabilitation exercises or activities of daily living in the early postoperative period before biological healing has occurred.

BONE MINERAL DENSITY Because intratunnel fixation methods depend on the graft fixation device generating friction between the bone tunnel wall and the ACL replacement graft, BMD is perhaps the most important variable that influences initial fixation strength and stiffness and resistance to slippage during cyclical loading. It is well known that BMD in humans decreases with age and that the BMD of females is less than that of males. Cassim et al21 found that the fixation strength of BPTB grafts fixed with metal interference screws in human specimens with a mean age of 79 years resulted in a 42% decrease in failure load compared with specimens with a mean age of 35 years. There are also significant differences in the BMD of the human distal femur and proximal tibia.22 The BMD of the proximal tibia is significantly lower than that of the distal femur.22 The lower BMD of 196

the proximal tibia, along with the fact that tibial fixation devices must resist shear forces applied parallel to the axis of the tibial bone tunnel, combine to make tibial fixation the weak link in ACL graft fixation. Although BMD is a critical factor, other variables correlate with initial fixation properties. In a BPTB model, Brown et al14 found that insertion torque, an indirect measure of BMD, was linearly correlated with pullout force but with weak significance. Using elderly human cadaveric knees, Brand et al22 found that BMD measured using dual-energy x-ray absorptiometry and screw insertion torque was strongly correlated to the fixation strength of doubled semitendinosus and gracilis tendons fixed with bioabsorbable interference screws in the distal femur and proximal tibia of human specimens. In this study, the variables of insertion torque and BMD explained 77% of the ultimate failure load observed. The R2 value for the relationship between ultimate failure load and BMD was 0.65, indicating that BMD explained 65% of the ultimate failure load. This study found that BMD of 0.6 gm/cm2 resulted in better initial fixation properties. Using the proximal tibia of human cadaveric specimens (mean age 40
11 years, range 17–54 years) and doubled tibialis tendons fixed with a tapered bioabsorbable screw, Jarvinen et al23 found that insertion torque was linearly correlated to fixation strength (R2 ¼ 0.54) and was the most strongly associated variable in their study for predictors of fixation strength. Unfortunately, despite the correlation, insertion torque was a poor predictor of cyclical loading failure or single LTF. Clearly, other secondary factors influence the properties of intratunnel graft fixation. The remainder of this chapter is aimed at understanding the role and importance of these other variables.

BONE–PATELLAR TENDON–BONE FIXATION Interference screw fixation of BTB ACL grafts has been well studied and documented over the past 20 years. The fixation properties of interference screw fixation of BTB grafts depend on the generation of friction between the bone block and bone tunnel wall. Friction is generated by compression of the bone block into the bone tunnel wall and engagement of the screw threads into the bone block and bone tunnel wall. As illustrated in Fig. 28-1, factors that influence the initial tensile properties of interference screw fixation of BTB ACL grafts include the following: 1 Screw diameter 2 Gap size 3 Screw length 4 Screw divergence

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation

28

A

B

C

D

E FIG. 28-1 Factors that influence the initial tensile properties of interference screw fixation of bone–tendon–bone anterior cruciate ligament grafts: (A), screw diameter, (B), gap size, (C), screw length, (D), short screw length, and (E), screw divergence.

197

Anterior Cruciate Ligament Reconstruction Overlap exists between the effects of screw diameter and gap size on initial fixation properties. In the study of Kurosaka et al,2 custom-made 9.0-mm screws demonstrated higher ultimate failure loads compared with 6.5-mm AO cancellous screws. However, the researchers reported that making the size of the patellar and tibial bone blocks close to the size of the bone tunnels was extremely important “in obtaining a solid fixation.”2 Using a porcine experimental model, Reznik et al24 demonstrated that gap size significantly influenced the ultimate failure load of BTB grafts fixed in 10-mm bone tunnels with 7-mm screws. When the gap between the bone block and bone tunnel wall was 4 mm or more, increasing the screw diameter to 9 mm increased the failure load by 97%. However, when the gap was less than 4 mm and a 9-mm screw was used, the results were inferior to those seen with a 7-mm screw and a gap of less than 4 mm. Kohn and Rose,25 using human cadaveric knees (mean age 30 years), reported that both femoral and tibial fixation using 9-mm screws were stronger than with 7-mm screws. Based on their findings, they recommended against using 7-mm screws for tibial fixation. However, Hulstyn et al,26 using a bovine femur– BPTB–tibia model found no significant difference in fixation strength between 7- and 9-mm screws. Using elderly human cadaveric specimens, Brown et al27 found no significant difference in the fixation strength of BPTB grafts fixed in the distal femur using endoscopically inserted 7-mm screws and 9-mm screws inserted using a rear-entry technique. Brown et al14 also found no difference in femoral fixation between 7- and 9-mm screws. The influence of screw diameter on initial fixation properties is probably most relevant when a significant size discrepancy exists between the bone block and the bone tunnel wall. This difference is often referred to as gap size. After studying various fixation methods, Kurosaka 2 et al hypothesized that the gap size between the bone block and bone tunnel was a critical factor in interference screw fixation. Cassim et al21 demonstrated the interrelationship between gap size and screw diameter in determining fixation strength in BPTB reconstruction. When the gap size was less than 1 mm and a 9-  30-mm screw was used, the mean ultimate failure load was 1060 N. Butler et al28 found that with a gap size of 3 to 4 mm, increasing the screw diameter size from 7 to 9 mm significantly increased the load at which failure occurred. A number of authors have suggested using larger screws as the gap size increases.29 Screw length probably does not have a large influence on the initial fixation properties of BPTB grafts fixed with interference screws. Brown et al27 found no significant difference in fixation strength between 7-  20-mm and 7-  30-mm screws or between 9-  20-mm and 9-  30-mm screws fixed in the distal femur of human specimens. Black et al30 compared 198

9-  12.5-mm, 9-  15-mm, and 9-  20-mm interference screws in a porcine tibia model. No significant difference in insertion torque, failure load, stiffness, or displacement to failure was found between the different lengths of screws. Pomeroy et al31 also found no significant effect of screw length on fixation strength for a given screw diameter. These findings may be explained by the fact that the length of the bone block is limited, and increasing the length of the screw does not lead to an increase in the number of screw threads in contact with the bone block and bone tunnel wall. Divergence of the interference screw from the bone block and the axis of the bone tunnel can occur with both rear-entry and endoscopic techniques. The incidence of screw divergence is more common with the endoscopic technique (femur > tibia).32 Based on clinical studies, screw divergence less than 30 degrees does not seem to have a significant effect on the clinical outcome.33 Using a porcine model, Jomha et al34 reported no significant difference in femoral fixation strength with endoscopically inserted interference screws with divergence up to 10 degrees. However, there was a significant drop in femoral fixation strength with screw divergence at 20 degrees. Pierz et al,35 using porcine tibiae, demonstrated that interference screws inserted to simulate a rear-entry femoral fixation technique or fixation of a tibial bone block resulted in a significant decrease in fixation strength from 0 to 15 degrees and 15 to 30 degrees of divergence. Interference screws inserted to simulate an endoscopic technique resulted in a significant decrease in fixation strength only at 30 degrees of screw divergence. These authors concluded that optimal interference screw fixation occurs when the screw is placed parallel to the bone block and bone tunnel. Due to the creation of a wedge effect, screw divergence has a lesser effect on endoscopically inserted femoral screws. However, due to the in-line direction of pull, minor degrees of divergence will affect the fixation strength of femoral screws inserted through a rear-entry technique and tibial fixation screws. Metal interference screws can distort MRI images, lacerate the graft during insertion, and complicate revision ACL surgery. Bioabsorbable interference screws have been proposed as a method to eliminate these potential complications.36 Several biomechanical studies have compared the initial fixation strength of bioabsorbable interference screws and conventional metal interference screws in animal and human cadaveric models. Weiler et al37 used a calf proximal tibia model to test the single LTF of six different biodegradable interference screws compared with that of a titanium interference screw. Five of the six bioabsorbable screws had failure loads and stiffness comparable with the metal screw. Similar results have been reported by Kousa et al,38 who found no significant difference in the tensile properties of BPTB grafts fixed with metal and bioabsorbable screws evaluated by single LTF and cyclical testing in a paired porcine model.

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation Concerns with bioabsorbable interference screws have focused largely on the issues of screw breakage and biocompatibility. Screw breakage has largely been addressed by designing screws and screwdrivers that allow the insertion torque to be distributed along the entire length of the screw and decreasing the insertion torque by notching the bone tunnel wall. To prevent breakage, it is important that the screwdriver be fully engaged during insertion of the screw. In summary, based on review of the literature, gap size is probably the most important factor influencing the initial fixation properties of interference screw fixation of BTB grafts. Gap size is also the one factor that can be easily measured intraoperatively and controlled by the surgeon. Improvements in initial graft fixation can be achieved by increasing the diameter of the screw to compensate for the gap size. Increasing screw length appears to offer minimal improvements in initial graft fixation properties.

GUIDELINES AND RECOMMENDATIONS FOR INTRATUNNEL FIXATION OF BONE–TENDON– BONE GRAFTS Femoral Fixation: Two-Incision Technique Use 8- or 9-mm-diameter metal screws with a length of 20 to 25 mm. Bioabsorbable screws can be used; however, the higher insertion torque generated by insertion of the screw against the hard cortex of the distal femur may result in a higher incidence of screw breakage compared with bioabsorbable screws inserted using an endoscopic technique. In situations where the gap between the bone block and bone tunnel wall is greater than 4 mm, suture/post or plastic button fixation should be considered.

Femoral Fixation: Endoscopic Technique Use 7- or 8-mm-diameter metal or bioabsorbable screws with a length of 20 to 25 mm. For bioabsorbable screws, review and use the manufacturer’s guidelines regarding tapping or notching the bone tunnel wall to minimize the risk of screw breakage. Use the Endobutton-CL in situations where the gap size is greater than 4 mm, in cases of grafts with long tendon lengths to prevent graft-tunnel mismatch, and in cases involving blowout of the posterior wall of the femoral tunnel.

Tibial Fixation Avoid use of 7-mm-diameter screws. Use 8- or 9-mmdiameter screws with a length of 20 to 25 mm. For gap sizes greater than 4 mm, consider suture/post or button fixation.

28

In soft bone or situations where low insertion torque is encountered, consider backing up the interference screw fixation by tying sutures around a fixation post.

SOFT TISSUE GRAFTS Interference screw fixation of soft tissue grafts depends on many of the same factors as fixation for BPTB grafts; however, the importance of each of these factors differs.39 Similar to BTB grafts, the initial fixation properties depend on the fixation device generating friction between the soft tissue graft and the bone tunnel wall. Friction is generated by compression of the soft tissue graft against the bone tunnel wall. However, because the soft tissue graft is more compressible than the bone blocks of BTB grafts, the amount of compression generated between the screw and bone tunnel wall for a given diameter of screw is less. The amount of friction contributed by engagement of the screw threads in the bone tunnel wall and soft tissue graft is also significantly lower due to the lack of engagement of the screw threads into the soft tissue graft. As illustrated in Fig. 28-2, factors that may contribute to the initial fixation properties of soft tissue grafts with interference screws include the following: 1 Screw geometry (length and diameter) 2 Tendon fit 3 Tunnel impaction or dilation 4 Screw placement (concentric versus eccentric) Unlike interference screw fixation of BTB grafts, screw length seems to have a greater effect on the initial fixation properties of soft tissue grafts fixed with interference screws. Because of the lower BMD of the proximal tibia, screw length has a greater influence on tibial fixation properties.22 Screw length may have a more significant effect on the fixation properties of soft tissue grafts because the area over which friction is generated between the bone tunnel wall and soft tissue graft is determined by the screw length rather than by the length of a bone block, which is typically 20 to 25 mm. In a bovine proximal tibia model, Weiler et al40 found that 23-mm screws had lower pullout strengths than 28-mm screws with equivalent diameters. This study also found that increasing screw length had a greater influence on failure load than increasing the screw diameter. Selby et al,41 using human tibias (age range 24–45 years), demonstrated significantly higher ultimate failure loads for 35-mm versus 28-mm screws. Harvey et al42 have investigated the effect of screw length and position using a bovine tibia model under cyclical loading conditions. Although not statistically significant, 45-mm-long metal screws demonstrated less slippage and “more consistent behavior” compared with 25-mm-long screws. Placement 199

Anterior Cruciate Ligament Reconstruction

A

B

Tendons

C

Screw

Tendons

D

FIG. 28-2 Factors that may contribute to the initial fixation properties of soft tissue grafts with interference screws: (A), screw geometry (length and diameter), (B), tendon fit, (C), tunnel impaction or dilation, and (D), screw placement (concentric versus eccentric).

of the screw such that it engaged the cortex of the tibia allowed significantly less slippage compared with screw insertion that engaged only cancellous bone. Based on their findings, the authors recommend that the screw head be placed such that it engages the tibial cortex. Few studies have examined the influence of screw diameter on the initial fixation properties of soft tissue ACL grafts with interference screws. Using human hamstring tendon grafts and bovine proximal tibiae, Weiler et al40 found that increasing the diameter of a 23-mm-long bioabsorbable interference screw from 7 to 8 mm increased the mean pullout force from 367 N to 479 N. The fit of the soft tissue graft in the bone tunnel appears to have a significant influence on the initial fixation properties of interference screw fixation of soft tissue grafts. Using a human cadaveric model, Steenlage et al43 demonstrated that four-strand hamstring tendon grafts fixed in the distal femur with a bioabsorbable screw resulted in a significantly higher ultimate failure load if the bone tunnel was sized within 0.5 mm of the graft diameter versus within 1 mm of the measured size of the graft. 200

Because BMD has such a significant effect on the initial tensile properties of interference screw fixation of soft tissue grafts, compaction drilling or bone tunnel dilation has been proposed as a method of creating increased bone density along the bone tunnel walls. It has been speculated that this will lead to an improvement in initial fixation properties. Using human male cadaveric knees, Rittmeister et al44 demonstrated that serial dilation did not improve the initial fixation strength of four-strand hamstring tendon grafts fixed in the tibia with metal interferences screws. Nurmi et al45 investigated the effects of compaction drilling versus conventional drilling on the initial fixation strength of four-strand hamstring tendon grafts fixed with bioabsorbable screws in the proximal tibia of human specimens (mean age 41
11 years, range 17–49 years). The biomechanical testing protocol consisted of cyclical loading followed by a single LTF test. They found no significant difference in initial stiffness or displacement between the two drilling methods during cyclical testing. In the single LTF test, there was no significant difference in yield load, displacement at yield load, or stiffness between the two drilling methods. The authors concluded that

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation compaction drilling does not increase the initial fixation properties of hamstring tendon grafts. In a second biomechanical study, Nurmi et al46 investigated the effect of tunnel compaction by serial dilators versus conventional drilling on the initial fixation strength of doubled anterior tibial tendons fixed in the proximal tibia of human specimens (mean age 40
11 years, range 17–54 years) using bioabsorbable interference screws. The specimens were tested under cyclical loading followed by a single LTF test. They found no significant difference in stiffness or displacement between the two techniques during cyclical testing. However, the number of failures during cyclical loading of the extraction drilling group was twice that of the serially dilated group. In the subsequent single LTF test, there was no significant difference in failure load or stiffness between the two groups. One of the limitations of this study was that the size of the tibial bone tunnel was not matched to the size of the soft tissue grafts, and a 10-mm-diameter bone tunnel was created in all specimens. The only study to demonstrate a beneficial effect of tunnel dilation on the fixation strength of soft tissue ACL grafts was performed by Cain et al47 using paired human cadaveric knees (average age 42 years, range 29–47 years). Four-strand hamstring tendon grafts were fixed with bioabsorbable screws in 0.5-mm matched femoral and tibial tunnels. The tibial tunnel was created using smooth tunnel dilators in one knee of the pair and conventional extraction drilling in the opposite knee of the pair. The femur-hamstring ACL graft–tibia complex was tested to failure using anterior tibial translation with the knee positioned in 20 degrees of flexion as previously described by Steiner et al.48 This method of testing attempts to mimic the Lachman test. All specimens failed due to the graft pulling out of the tibial tunnel. However, the ultimate failure load was reported to be significantly higher for the dilated tibial tunnels. Testing methodology makes it difficult to compare the results of this study with earlier studies; however, based on the literature, the benefits of compaction drilling or serial dilation seem to be marginal at best and probably do not justify the extra costs and operating time. Although it is generally agreed that interference screws should be inserted on the cancellous side of BTB grafts, controversy exists regarding placement of tibial interference screws used to fix multistrand hamstring tendon grafts. Soft tissue grafts may be fixed by inserting the screw on the side (eccentrically) or down the center (concentrically) of the graft strands. Concentric screw placement maximizes contact between the graft strands and the bone tunnel wall, providing a greater surface area for healing. Simonian et al49 investigated the effect of screw eccentric versus concentric placement on initial fixation properties using human hamstring tendon grafts fixed in a polyurethane foam model. There were no differences in the ultimate failure load or slippage between the two screw

28

positions. Shino and Pflaster50 investigated the effect of eccentric versus concentric screw placement on the initial fixation properties of four-strand hamstring tendon grafts fixed in the proximal tibia of paired human cadaveric knees (average age 51 years, range 49–54 years). There were no significant differences in stiffness, yield load, ultimate failure load, or slippage between the two screw positions. Unlike BTB grafts in which the bone tunnel size and dimensions of the bone blocks are standardized, there are large variations in the diameter and length of soft tissue grafts, making it difficult to arrive at definitive recommendations regarding selection of interference screw fixation. Nevertheless, our interpretation of the literature has led to the following conclusions: 1 Because of the lower BMD and the fact that the line of applied force is parallel to the axis of the tibial tunnel, tibial fixation is weaker, less stiff, and more likely to slip under cyclical loading compared with the femoral fixation site. 2 Screw length has a more significant effect on the initial fixation properties of interference screw fixation of soft tissue ACL grafts compared with BTB ACL grafts. 3 Longer screws seem to result in higher ultimate failure loads and stiffness and less slippage. 4 Fixation properties are improved by having the screw head engage the tibial cortex. 5 The effect of screw diameter on initial fixation properties is unclear, making it difficult to establish clear guidelines for screw sizing. 6 Matching the size of the bone tunnel to within 0.5 mm of the measured size of the graft seems advisable. 7 Compaction drilling or serial dilation does not seem to significantly improve initial fixation properties.

ALTERNATIVE INTRATUNNEL TIBIAL FIXATION TECHNIQUES The stimulus for the development of alternative intratunnel tibial fixation techniques for soft tissue ACL grafts arose from the desire to decrease slippage and the high rate of fixation failure reported with interference screws under cyclical loading conditions, to eliminate or reduce the need for supplemental tibial fixation, and to improve soft tissue–to-bone healing at the graft fixation sites.39,42,51 The IntraFix (DePuy Mitek, Norwood, MA) was designed to individually capture each of the four strands of a soft tissue graft in a separate compartment using a plastic sheath and to achieve direct compression of each of the graft strands 201

Anterior Cruciate Ligament Reconstruction against the bone tunnel wall by the insertion of a tapered screw into the central chamber of the plastic sheath.52 In a porcine tibia model using human hamstring tendon grafts, Kousa et al53 demonstrated that the IntraFix had the highest load failure load (1309
302 N) and stiffness (267
36 N/mm) and the least amount of slippage (1.5 mm) after cyclical loading compared with two cortical fixation techniques and three other interference screw fixation techniques. The GTS System (Graft Tunnel Solution) (Smith & Nephew Endoscopy, Andover, MA) is an intratunnel tibial fixation technique that positions a poly-L-lactic acid (PLLA)-tapered, fine-pitch screw concentrically within the four-strand soft tissue graft.54 The screw features a tapered design and shorter thread distance, which enhances compression of the soft tissue graft in cancellous bone. The Graft Sleeve is a three-lumen, woven, nonabsorbable polypropylene (PPE) mesh graft sleeve that organizes the four-strand soft tissue graft in the tibial tunnel. The Graft Sleeve prevents graft twisting during screw insertion, which helps maintain equal tension in the four graft strands; maximizes bone-tendon contact, which enhances healing; and provides better compression of each ligament strand against the bone tunnel wall while protecting the graft strands from screw damage. Cyclical testing followed by single LTF testing of the Graft Sleeve and Tapered Screw and IntraFix has been performed using human doubled gracilis and semitendinosus tendon grafts (DGST) in the proximal tibia of calf bone (2 years or younger) with BMD similar to that of the proximal tibia in young humans. There were no significant differences in slippage, ultimate failure load, or stiffness between the two devices.

FUTURE DIRECTIONS The ideal ACL graft fixation method would provide immediate rigid fixation that is sufficiently strong and stiff and able to resist slippage such that permanent elongation does not develop with the stresses of rehabilitation and activities of daily living. The fixation method should be low profile and should not require later removal because of local irritation and pain. Ideally, the device should be replaced by cancellous bone and result in the development of a normal histological ligament–bone attachment site. Future improvements in intratunnel ACL graft fixation will depend on better understanding the in vivo forces experienced by the ACL with rehabilitation exercises and activities in the early postoperative period and the biology of fixation site healing. Osteoconductive or osteoinductive materials that will stimulate the development of normal osseous tissue are currently under development. Bone cement, which will provide immediate rigid fixation and then be eventually replaced by bone, may be developed. 202

There is ongoing basic science research directed at promoting and accelerating healing of soft tissue to bone. Ultrasound, bone morphogenic proteins (BMPs), and biological growth factors are currently being investigated as possible methods to promote and accelerate tendon-to-bone healing.

References 1. Lambert KL. Vascularized patellar tendon graft with rigid internal fixation for anterior cruciate ligament insufficiency. Clin Orthop 1983;172:85–89. 2. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med 1987;15:225–229. 3. Steiner ME, Hecker AT, Brown CH, Jr, et al. Anterior cruciate ligament graft fixation: comparison of hamstring and patellar tendon grafts. Am J Sports Med 1994;22:240–247. 4. Bach BR, Jr, Tradonsky S, Bojchuk J, et al. Arthroscopically assisted anterior cruciate ligament reconstruction using patellar tendon autograft. Five-to nine-year follow-up evaluation. Am J Sports Med 1998;26:20–29. 5. Pinczewski L. In Endoscopic ACL reconstruction utilizing a quadrupled hamstring tendon autograft with direct RCI interference screw fixation. Presented at Lecture/Laboratory Session of RCI Screw, Smith & Nephew Donjoy, Columbus, GA, Feb 1996. 6. Morrison JB. Function of the knee joint in various activities. Biomed Eng 1969;4:573–580. 7. Morrison JB. The mechanics of the knee joint in relation to normal walking. J Biomech 1970;3:51–61. 8. Noyes FR, Butler DL, Grood E, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg 1984;66A:344–352. 9. Cooper DE, Deng XH, Burstein AL, et al. The strength of central third patellar tendon graft: a biomechanical study. Am J Sports Med 1993;21:818–823. 10. Hamner DL, Brown CH, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg 1999;81A:549–557. 11. Brand JC, Weiler A, Caborn DNM, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 12. Beynnon BD, Amis AA. In vitro testing protocols for the cruciate ligaments and ligament reconstructions. Knee Surg Sports Traumatol Arthrosc 1998;6(suppl 1):S70–S76. 13. Weiss JA, Paulos LE. Mechanical testing of ligament fixation devices. Techn Orthop 1999;14:14–21. 14. Brown GA, Pena F, Grontvedt T, et al. Fixation strength of interference screw fixation in bovine, young human, and elderly human cadaver knee: influence of insertion torque, tunnel-bone block gap and interference. Knee Surg Sports Traumatol Arthrosc 1996;3:238–244. 15. Aerssens J, Boonen S, Lowet G, et al. Interspecies differences in bone composition, density, and quality: potential implications for in vivo bone research. Endocrinology 1998;139:663–670. 16. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 17. Nurmi JT, Sievanen H, Kannus P, et al. Porcine tibia is a poor substitute for human cadaver tibia for evaluating interference screw fixation. Am J Sports Med 2004;32:765–771. 18. Clancy WG, Jr, Narechania RG, Rosenberg TD, et al. Anterior and posterior cruciate ligament reconstruction in rhesus monkeys. A histological microangiographic and biomechanical analysis. J Bone Joint Surg 1981;63A:1270–1284. 19. Walton M. Absorbable and metal interference screws: comparison of graft security during healing. Arthroscopy 1999;15:818–826.

Biomechanics of Intratunnel Anterior Cruciate Ligament Graft Fixation 20. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 21. Cassim A, Lobenhoffer P, Gerich T, et al. The fixation strength of the interference screw in anterior cruciate ligament replacement as a function of technique and experimental setup. Trans Ortho Res Soc 1993;18:31. 22. Brand JC, Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 23. Jarvinen TL, Nurmi JT, Sievanen H. Bone density and insertion torque as predictors of anterior cruciate ligament graft fixation strength. Am J Sports Med 2004;32:1421–1429. 24. Reznik AM, Davis JL, Daniel DM. Optimizing interference fixation for cruciate ligament reconstruction. Trans Orthop Res Soc 1990;15:519. 25. Kohn D, Rose C. Primary stability of interference screw fixation: influence of screw diameter and insertion torque. Am J Sports Med 1994;22:334–338. 26. Hulstyn M, Fadale PD, Abate J, et al. Biomechanical evaluation of interference screw fixation in a bovine patellar bone-tendon-bone autograft complex for anterior cruciate ligament reconstruction. Arthroscopy 1993;9:417–424. 27. Brown CH, Hecker AT, Hipp JA, et al. The biomechanics of interference screw fixation of patellar tendon anterior cruciate ligament grafts. Am J Sports Med 1993;21:880–886. 28. Butler JC, Branch TP, Hutton WC. Optimal graft fixation—the effect of gap size and screw size on bone plug fixation in ACL reconstruction. Arthroscopy 1994;10:524–529. 29. Fithian DC, Daniel DM, Casanave A. Fixation in knee ligament repair and reconstruction. Oper Tech Orthop 1992;2:63–70. 30. Black KP, Saunders MM, Stube KC, et al. Effects of interference fit screw length on tibial tunnel fixation for anterior cruciate ligament reconstruction. Am J Sports Med 2000;28:846–849. 31. Pomeroy G, Baltz M, Pierz K, et al. The effects of bone plug length and screw diameter on the holding strength of bone-tendon-bone grafts. Arthroscopy 1998;14:148–152. 32. Lemos MJ, Albert J, Simon T, et al. Radiographic analysis of femoral interference screw placement during ACL reconstruction: endoscopic versus open technique. Arthroscopy 1993;9:154–158. 33. Dworsky BD, Jewell BF, Bach BR. Interference screw divergence in endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1996;12:45–49. 34. Jomha NM, Raso VJ, Leung P. Effect of varying angles on the pullout strength of interference screw fixation. Arthroscopy 1993;9:580–583. 35. Pierz K, Baltz M, Fulkerson J. The effect of Kurosaka screw divergence on the holding strength of bone-tendon-bone grafts. Am J Sports Med 1995;23:332–335. 36. Barber FA, Elrod BF, McGuire DA, et al. Preliminary results of an absorbable interference screw. Arthroscopy 1995;11:537–548. 37. Weiler A, Windhagen HJ, Raschke MJ, et al. Biodegradable interference screw fixation exhibits pull-out force and stiffness similar to titanium screws. Am J Sports Med 1998;26:119–128. 38. Kousa P, Järvinen TL, Kannus P, et al. Initial fixation strength of bioabsorbable and titanium interference screws in anterior cruciate

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ligament reconstruction: biomechanical evaluation by single cycle and cyclic loading. Am J Sports Med 2001;29:420–425. Brand JC, Caborn DNM, Johnson DL. Biomechanics of soft-tissue interference screw fixation of anterior cruciate ligament reconstruction. Orthopedics 2003;26:432–439. Weiler A, Hoffmann RF, Siepe CJ, et al. The influence of screw geometry on hamstring tendon interference fit fixation. Am J Sports Med 2000;28:356–359. Selby JB, Johnson DL, Hester P, et al. Effect of screw length on bioabsorbable interference screw fixation in a tibial bone tunnel. Am J Sports Med 2001;29:614–619. Harvey AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction. Knee 2003;10:97–102. Steenlage E, Brand JC, Jr, Johnson DL, et al. Correlation of bone tunnel diameter with quadrupled hamstring graft fixation strength using a biodegradable interference screw. Arthroscopy 2002;18:901–907. Rittmeister ME, Noble PC, Bocell JR, Jr, et al. Interactive effects of tunnel dilation on the mechanical properties of hamstring grafts fixed in the tibia with interference screws. Knee Surg Sports Traumatol Arthrosc 2001;9:267–271. Nurmi JT, Kannus P, Sievänen H, et al. Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in anterior cruciate ligament reconstruction in a cadaver model. Am J Sports Med 2003;31:353–358. Nurmi JT, Kannus P, Sievänen H, et al. Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction: part 1. Effect of tunnel compaction by serial dilators versus extraction drilling on the initial fixation strength. Am J Sports Med 2004;32:411–417. Cain EL, Phillips BB, Charlebois SJ, et al. Effect of tibial tunnel dilation on pullout strength of semitendinosus-gracilis graft in anterior cruciate ligament reconstruction. Orthopedics 2005;28:779–783. Steiner ME, Hecker AT, Brown CH, Jr, et al. Anterior cruciate ligament graft fixation: comparison of hamstring and patellar tendon grafts. Am J Sports Med 1994;22:240–246. Simonian PT, Sussmann PS, Baldini TH, et al. Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction. Arthroscopy 1998;14:459–464. Shino K, Pflaster DS. Comparison of eccentric and concentric screw placement for hamstring graft fixation in the tibial tunnel. Knee Surg Sports Traumatol Arthrosc 2000;8:73–75. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. Sklar JH, Brown CH, Jr. Soft tissue anterior cruciate ligament reconstruction with the IntraFix tibial fastener. Tech Orthop 2005;20:283–289. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. Brown CH, Jr, Darwich N. Anterior cruciate ligament reconstruction using autogenous doubled gracilis and semitendinosus tendons with GTS sleeve and tapered screw tibial fixation. Tech Orthop 2005;20:290–296.

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29 CHAPTER

Stephen M. Howell

High-Stiffness, Slippage-Resistant Cortical Fixation Has Many Advantages over Intratunnel Fixation INTRODUCTION This chapter explains why the fixation properties of high stiffness and resisting slippage are the two critical factors in restoring anterior laxity to a knee reconstructed with an anterior cruciate ligament (ACL) graft. Definitions and examples of highand low-stiffness fixation are provided, along with evidence that high-stiffness cortical fixation placed away from the joint line restores anterior laxity as well as intratunnel fixation with an interference screw, even though the graft is a few centimeters longer. Resisting slippage, the most important fixation property, goes hand-in-hand with stiffness. A fixation device that resists slippage also provides high stiffness; however, the reverse relationship does not hold true. A discussion is included of the extensive biological and mechanical advantages of the use of high-stiffness, slippage-resistant cortical fixation over intratunnel fixation, including a more rapid, stronger, and stiffer tendon–tunnel biological bond; a stronger, stiffer, and more slippage-resistant mechanical fixation; and less tunnel widening. A rationale for selecting a soft tissue fixation device is presented. The surgeon reading this chapter should find these basic engineering principles useful when designing his or her own ACL reconstruction technique.

FIXATION STIFFNESS AND SLIPPAGE: CRITICAL FACTORS IN RESTORING ANTERIOR LAXITY An ACL graft construct is composed of the ACL graft and the two fixation devices at either 204

end (Fig. 29-1). Anterior laxity in the knee of the athlete returning to sport is determined by the stiffness of the ACL graft construct and the length of the ACL graft, not by the strength of the graft and the tension in the graft.1–4 The stiffness of the ACL graft construct determines anterior laxity, the firmness of the Lachman test, and the quality of the “endpoint.” The stiffness of the ACL graft construct is increased more by the use of stiffer fixation devices than by the use of a shorter graft. A short graft with elastic fixation does not restore anterior laxity as well as a longer graft with stiffer fixation.5,6 The concept that shortening the graft increases the stiffness of the ACL graft construct, as proposed by some studies,7–9 is incorrect when high-stiffness, slippage-resistant cortical fixation devices are used.4 The most effective way to construct a stiff ACL graft and restore a firm Lachman test is to use high-stiffness, slippage-resistant cortical fixation devices on both ends of the graft.1,3,5,6 A determinant of anterior laxity that is as equally determinant as the stiffness of the ACL graft construct is maintenance of the length of the ACL graft set at the time of fixation. Maintaining the initial set length of the ACL graft after implantation requires the use of fixation devices that resist slippage during cyclical loading and exercise. Fortunately, there are fixation devices that do resist slippage and provide high stiffness; however, they are applied at the distal end of the tunnels and engage cortical bone, which is 30 times stronger than cancellous bone.5,10–12 The use of intratunnel devices such

High-Stiffness, Slippage-Resistant Cortical Fixation Has Many Advantages over Intratunnel Fixation

29

Bone Mulch Screw EZLoc

Bone graft

Bone graft

WasherLoc

FIG. 29-1 An anterior cruciate ligament (ACL) graft construct is composed of the ACL graft and the fixation devices used on the femur and tibia. The anterior laxity is determined by the stiffness of the ACL graft construct and the ability of the fixation devices to prevent slippage of the graft during cyclical exercise and early exercise. Intratunnel devices such as the interference screw and IntraFix are stiff but slip readily under cyclical load. Examples of high-stiffness fixation devices that also resist slippage and are used in the femur include the EZLoc and Bone Mulch Screw with bone graft. Examples of high-stiffness fixation that resist slippage and are used at the distal end of the tibial tunnel include the WasherLoc, with or without bone dowel.

as the interference screw and IntraFix (DePuy Mitek, Norwood, MA) do not resist slippage, and the ACL graft readily elongates under cyclical load.5,13–15 Therefore the use of high-stiffness, slippage-resistant cortical fixation that purchases cortical bone is the best strategy for maintaining the initial length of the ACL graft and compensating for the obligatory loss in tension from cyclical movement of the knee and exercise (Fig. 29-2).2,3

DEFINITION AND EXAMPLES OF HIGH- AND LOW-STIFFNESS FIXATION High-stiffness fixation can be arbitrarily defined as a fixation stiffness that is greater than 400 N/mm when tested in young human bone. The WasherLoc with bone dowel (stiffness of 565 N/mm), the WasherLoc alone (506 N/mm), and tandem screws and washers placed on the cortex distal to the tibial tunnel (414 N/mm) all provide stiffness greater than 400 N/ mm in young human bone (see Fig. 29-1). On the femoral side, the EZLoc (infinite stiffness) and Bone Mulch Screw

(575 N/mm) are high-stiffness fixations because they purchase cortical bone, which is 30 times stronger than cancellous bone. Each of these high-stiffness cortical fixation devices resists slippage well during cyclical loading.5,6,11,16–20 In contrast, low-stiffness fixation provides less than 400 N/mm in young human bone (Fig. 29-3). The interference screw (340 N/mm), double staples placed in the cortex distal to the tibial tunnel (174 N/mm), sutures tied to a post (70 N/mm), closed loop Endobutton (79 N/mm), IntraFix (49 N/mm), and sutures tied to an Endobutton (25 N/mm) are all examples of fixation devices that provide low stiffness. None of these low-stiffness intratunnel and cortical fixation devices resists slippage well during cyclical loading.*

COMMENT ABOUT INTRATUNNEL FIXATION WITH AN INTERFERENCE SCREW The location of fixation of an ACL graft with respect to the joint line has been a topic of debate.17,22–24 Proponents of *

References 2, 5, 6, 12, 13, 21.

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FIG. 29-2 The loss of intraarticular graft tension (IAT) and increase in anterior laxity (maximal anterior translation) with low-stiffness double staple fixation is shown after a series of treatments designed to simulate exercise. All the tension in the graft was lost after cyclical loading of the knee 20 times to a maximum tensile load in the graft of 170N.

fixation of an ACL graft at the level of the joint line with an interference screw base their opinion on two studies.7,9 The seminal study showed that anterior laxity was better restored with intratunnel fixation with an interference screw than with double staples applied distal to the tibial tunnel in porcine knees.7 A subsequent study showed that anterior laxity was better restored with intratunnel fixation with an interference screw than with sutures tied to a post in human knees.9 The explanation offered for the better restoration of anterior laxity with intratunnel fixation with an interference screw versus cortical fixation with double staples and

FIG. 29-3 Examples of low-stiffness cortical fixation that poorly resist slippage include the double staples (belt buckle) and sutures tied to a post. These fixation devices, along with the intratunnel devices such as the interference screw and IntraFix, slip readily under cyclical loading, and their use with aggressive rehabilitation should be approached cautiously.

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sutures tied to a post was that intratunnel fixation shortens the effective length of the graft, which increases the stiffness of the knee.7–9 More recent studies have questioned the use of double staples, sutures tied to a post, and porcine knees to study the effect of the level of fixation on anterior laxity and knee stiffness. Double staples (174 N/mm) and sutures tied to a post (70 N/mm) are low-stiffness fixation devices (i.e., <200 N/ mm), whereas distal tibial fixation devices such as tandem screws and washers (414 N/mm), WasherLoc (506 N/mm), and WasherLoc and bone dowel (565 N/mm) are high-stiffness fixation devices (i.e., >400 N/mm).5,17 Furthermore, these high-stiffness cortical fixation devices provide greater stiffness than interference screw fixation (340 N/mm) as well as greater strength and less slippage.5,9,16–18 Two studies have concluded that a porcine knee is not a reasonable surrogate for a human knee for evaluating the fixation structural properties of the interference screw in ACL reconstructions.5,15 Porcine bone overestimates the stiffness of the interference screw (476 N/mm) in comparison to young human tibia (340 N/mm) and overestimates the strength and underestimates slippage as well.5 Because the fixation structural properties of each of these high-stiffness cortical fixation devices are superior to those of the interference screw, they each might restore anterior laxity and knee stiffness in a human knee, even though the effective length of the graft is longer.5,17,18 A more contemporary study that used high-stiffness, slippage-resistant cortical fixation has dispelled the dogma that intratunnel fixation with an interference screw provides more acute stability to the reconstructed knee (Fig. 29-4).4 This in vitro cadaver study using human bone evaluated the anterior laxity and knee stiffness provided by tandem screws

High-Stiffness, Slippage-Resistant Cortical Fixation Has Many Advantages over Intratunnel Fixation

Tandem screws and washers

Interference screw

WasherLoc

29

WasherLoc and bone dowel

FIG. 29-4 The dogma that intratunnel fixation with an interference screw restores the acute stability of the reconstructed knee better than cortical fixation was dispelled by a more contemporary study, which used highstiffness, slippage-resistant cortical fixation instead of low-stiffness cortical fixation with double staples and suture. Tandem screws and washers, WasherLoc, and WasherLoc and bone dowel restored anterior laxity and knee stiffness as well as intratunnel fixation with an interference screw.

and washers placed distal to the tibial tunnel, WasherLoc placed at the end of the tibial tunnel, and WasherLoc and bone dowel compared with an interference screw placed to the level of the joint line. Anterior laxity normalized to the intact knee with these three cortical fixation techniques of tandem washers, WasherLoc, WasherLoc and bone dowel. Each restored anterior laxity as well as intratunnel fixation with an interference screw. The additional stiffness provided by the cortical fixation device compensated for the slight reduction in ACL graft stiffness caused by the added length, which enabled the cortical fixation to restore anterior laxity as well as intratunnel fixation with an interference screw. This finding is in contrast to Ishibashi’s study7 in porcine bone in which an interference screw placed at the joint line distal in the tibial tunnel provided better stability than staples placed distal to the tibial tunnel. One reason for these different findings in Ishibashi’s study compared with the study that used high-stiffness cortical fixation5 is that the interference screw provides 598 N/mm in porcine bone but only 350 N/mm in human bone. The cancellous bone has a higher density in a porcine knee than in a knee from a young individual, which overestimates the stiffness and strength and underestimates slippage of interference screw fixation when compared with young human tibia.5,15 Another reason for these different findings is that Ishibashi’s study underestimated the performance of the cortical fixation because it evaluated one of the least stiff cortical fixations—the double staples (174 N/mm)—instead of a high-stiffness, slippageresistant cortical fixation. The overestimation of the performance of the interference screw in porcine bone suggests Ishibashi et al’s findings (i.e., that the level of fixation in porcine bone affects anterior laxity) should not be applied to a knee in young individuals.4 A second study by Sheffler et al confirmed Ishibashi et al’s findings by showing that low-stiffness cortical fixation

does not restore anterior laxity as well as intratunnel fixation with an interference screw in human bone. Again, the authors underestimated the performance of the cortical fixation because they used the least stiff cortical fixation, which is a suture tied to a post (74 N/mm).9 In conclusion, high-stiffness, slippage-resistant cortical fixation devices restore anterior laxity and knee stiffness as well as intratunnel fixation with an interference screw fixation. This is different from the use of low-stiffness cortical fixation, which does not restore anterior laxity as well as intratunnel fixation with an interference screw. This leads to the principle that anterior laxity and knee stiffness are determined by the stiffness of the fixation device and not the location of the fixation device with respect to the joint line.1,4,6

EXAMPLE OF STIFFNESS PRINCIPLE The importance of including the stiffness of the fixation device when determining the effect of the fixation device on the anterior laxity of the knee can be illustrated by the following example (Fig. 29-5). Consider a knee reconstructed with a soft tissue graft in which the femoral fixation is a rubber (lowstiffness) cross-pin placed near the joint line, and the tibial fixation is high-stiffness, slippage-resistant cortical fixation with a WasherLoc and bone dowel. Compare the anterior laxity with a low-stiffness rubber cross-pin placed at the joint line to a knee with a high-stiffness steel cross-pin placed farther from the joint line. The stiffness of the knee with the rubber cross-pin is extremely low even though the effective length of the graft is short. The stiffness of the knee with the metal cross-pin is high even though the effective length of the graft is long. Anterior laxity is better restored in the knee with the metal cross-pin and the longer effective graft length because the added stiffness provided by the fixation device more than 207

Anterior Cruciate Ligament Reconstruction Joint Line Fixation

Distal Fixation

High-stiffness metal cross-pin Low-stiffness rubber cross-pin

FIG. 29-5 Intratunnel fixation with a low-stiffness fixation device near the joint line, such as a rubber cross-pin, does not restore anterior laxity and knee stiffness as well as more distal fixation with a metal cross-pin, even though the graft is shorter. The stiffness of the fixation is a more important determinant of the anterior laxity and stiffness of the knee than the location of the fixation device with respect to the joint line.

compensates for the small increase in the effective length of the graft and because the graft is generally stiffer than the fixation device. 1,3–6

BIOLOGICAL AND MECHANICAL ADVANTAGES OF CORTICAL FIXATION OVER INTRATUNNEL FIXATION The biological advantages of high-stiffness, slippage-resistant cortical fixation over intratunnel fixation with an interference screw include better healing because of the longer tunnel, circumferential healing of all sides of the graft to the tunnel wall, and the ability to bone graft the tunnel (Fig. 29-6). The biological bond between the tendon and tunnel wall is significantly stiffer and stronger in a longer tunnel than in a shorter tunnel because there is more bone surface area for the tendon to heal.27 Cortical fixation also allows circumferential biologic healing so that all sides of the tendon within the tunnel can heal to the bone. The interference screw blocks or “interferes” with healing on one side of the tendon, which causes a reduction of stiffness, slippage, and loss of strength 4 weeks after implantation that does not occur with cortical fixation.24 The use of high-stiffness, slippage-resistant fixation also allows bone grafting of the tibial tunnel.17 Bone grafting increases the snugness of fit between the tendon and tunnel 208

FIG. 29-6 A tibialis allograft is fixed at the end of the femoral tunnel with the EZLoc and the end of the tibial tunnel with a WasherLoc and bone dowel. Long, snug tunnels promote tendon healing and allow the tendon to heal circumferentially to the tunnel wall. The addition of the bone dowel can be seen filling the anterior half of the distal half of the tibial tunnel. The use of an intratunnel device such as the interference screw and IntraFix “interferes” with tendon healing by decreasing the contact area between the tendon and tunnel wall.

wall and, as a biologically active component, may promote tendon tunnel healing.17,27,28 The mechanical advantage of cortical fixation over intratunnel fixation is that the cortical fixation device grips cortical bone instead of cancellous bone.10 Cortical bone is 30 times stronger than cancellous bone and is not as affected by other variables such as disuse, gender, age, alcohol, and smoking. Cortical fixation is stiffer, slips less, and is stronger than cancellous fixation with devices such as the interference screw or IntraFix.5,6,10,12,13 Cortical fixation permits bone grafting of the tunnel, which increases the stiffness 58 N/ mm on the tibial side and 41 N/mm on the femoral side.6,17

PREFERRED FIXATION TECHNIQUE Based on these observations of these various studies and the “stiffness principle,” we prefer to fix a soft tissue graft with high-stiffness, slippage-resistant cortical fixation that purchases cortical bone (Fig. 29-7). On the femoral side, the EZLoc rigidly suspends the graft from the cortex, which moves the fixation point from the cortical surface to inside

High-Stiffness, Slippage-Resistant Cortical Fixation Has Many Advantages over Intratunnel Fixation

29

Intratunnel fixation with an interference screw or IntraFix, although stiff, does not resist slippage, interferes with tendon tunnel healing, and loses its effectiveness as cancellous bone softens. Choosing the stiffness of the two fixation devices is a more important determinant in restoring anterior laxity and knee stiffness than trying to shorten the effective length of the graft.

References

FIG. 29-7 The EZLoc in the femur and WasherLoc with bone dowel in the tibia are examples of high-stiffness, slippage-resistant, strong cortical fixation that grip cortical bone. The rigid fixation of the EZLoc in the femur without micromotion allows bone ingrowth around the implant (arrows), and there is no tunnel widening. On the tibial side, the bone dowel (arrows) has reduced the tunnel diameter, preventing tunnel widening.

the femoral tunnel. This tends to shorten the graft length but also preserves 25 to 30 mm of graft in the femoral tunnel so that circumferential biological healing can take place. Slippage of this construct does not occur because the lever arm sits directly on cortical bone and the graft is looped within a rigid metal slot. On the tibial side, the WasherLoc engages cortical bone and allows access to the tibial tunnel for the addition of a bone dowel or bone graft. The WasherLoc placed at the end of the tibial tunnel also preserves 30 to 35 mm of graft in the tunnel and allows circumferential tendon tunnel healing to take place.

CONCLUSION This chapter emphasizes the importance of choosing fixation devices that provide high stiffness and resist slippage under cyclical load and exercise. Fixation devices with these properties purchase cortical bone at the end of the femoral and tibial tunnels. These cortical fixation devices restore anterior laxity and knee stiffness as well as intratunnel fixation, even though the effective length of the graft is a few centimeters longer.

1. Eagar P, Hull ML, Howell SM. How the fixation method stiffness and initial tension affect anterior load-displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft. J Orthop Res 2004;22:613–624. 2. Grover DM, Howell SM, Hull ML. Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices. J Bone Joint Surg 2005;87A:381–390. 3. Karchin A, Hull ML, Howell SM. Initial tension and anterior loaddisplacement behavior of high-stiffness anterior cruciate ligament graft constructs. J Bone Joint Surg 2004;86A:1675–1683. 4. Liu-Barba D, Howell SM, Hull ML. High stiffness cortical fixation restores anterior laxity and knee stiffness as well as intratunnel fixation with an interference screw: a cadaveric study of human knees reconstructed with a soft tissue anterior cruciate ligament graft. In press. 5. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 6. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 7. Ishibashi Y, Rudy TW, Livesay GA, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system. Arthroscopy 1997;13:177–182. 8. Morgan CD, Stein DA, Leitman EH, et al. Anatomic tibial graft fixation using a retrograde bio-interference screw for endoscopic anterior cruciate ligament reconstruction. Arthroscopy 2002;18:E38. 9. Scheffler SU, Sudkamp NP, Gockenjan A, et al. Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: the impact of fixation level and fixation method under cyclic loading. Arthroscopy 2002;18:304–315. 10. Amis AA. The strength of artificial ligament anchorages. A comparative experimental study. J Bone Joint Surg Br 1988;70:397–403. 11. Bailey SB, Grover DM, Howell SM, et al. Foam-reinforced elderly human tibia approximates young human tibia better than porcine tibia: a study of the structural properties of three soft tissue fixation devices. Am J Sports Med 2004;32:755–764. 12. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 13. Caborn DN, Brand JC Jr, Nyland J, et al. A biomechanical comparison of initial soft tissue tibial fixation devices: the IntraFix versus a tapered 35-mm bioabsorbable interference screw. Am J Sports Med 2004;32:956–961. 14. Giurea M, Zorilla P, Amis AA, et al. Comparative pull-out and cyclicloading strength tests of anchorage of hamstring tendon grafts in anterior cruciate ligament reconstruction. Am J Sports Med 1999;27:621–625. 15. Nurmi JT, Sievanen H, Kannus P, et al. Porcine tibia is a poor substitute for human cadaver tibia for evaluating interference screw fixation. Am J Sports Med 2004;32:765–771. 16. Coleridge SD, Amis AA. A comparison of five tibial-fixation systems in hamstring-graft anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:391–397.

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Anterior Cruciate Ligament Reconstruction 17. Howell SM, Roos P, Hull ML. Compaction of a bone dowel in the tibial tunnel improves the fixation stiffness of a soft tissue anterior cruciate ligament graft: an in vitro study in calf tibia. Am J Sports Med 2005;33:719–725. 18. Kousa P, Jarvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 19. Roos PJ, Hull ML, Howell SM. Lengthening of double-looped tendon graft constructs in three regions after cyclic loading: a study using Roentgen stereophotogrammetric analysis. J Orthop Res 2004;22:839–846. 20. Smith CK, Hull ML, Howell SM. Lengthening of a single-loop tibialis tendon graft construct after cyclic loading: a study using roentgen stereophotogrammetric analysis. J Biomech Eng 2006;128:437–442. 21. Hoher J, Livesay GA, Ma CB, et al. Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation. Knee Surg Sports Traumatol Arthrosc 1999;7:215–219. 22. Brown CH Jr, Wilson DR, Hecker AT et al. Graft-bone motion and tensile properties of hamstring and patellar tendon anterior cruciate

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23.

24.

25. 26.

27.

28.

ligament femoral graft fixation under cyclic loading. Arthroscopy 2004;20:922–935. Ma CB, Francis K, Towers J, et al. Hamstring anterior cruciate ligament reconstruction: a comparison of bioabsorbable interference screw and endobutton-post fixation. Arthroscopy 2004;20:122–128. Singhatat W, Lawhorn KW, Howell SM, et al. How four weeks of implantation affect the strength and stiffness of a tendon graft in a bone tunnel: a study of two fixation devices in an extraarticular model in ovine. Am J Sports Med 2002;30:506–513. Morgan CD, Kalmam VR, Grawl DM. Isometry testing for anterior cruciate ligament reconstruction revisited. Arthroscopy 1995;11:647–659. Weiler A, Hoffmann RF, Stahelin AC, et al. Hamstring tendon fixation using interference screws: a biomechanical study in calf tibial bone. Arthroscopy 1998;14:29–37. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. Kyung HS, Kim SY, Oh CW, et al. Tendon-to-bone tunnel healing in a rabbit model: the effect of periosteum augmentation at the tendon-tobone interface. Knee Surg Sports Traumatol Arthrosc 2003;11:9–15.

Tibial Fixation for Anterior Cruciate Ligament Hamstring Grafts: 10 Techniques that Improve Fixation

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INTRODUCTION

Lonnie E. Paulos

Tibial fixation during hamstring anterior cruciate ligament (ACL) reconstruction has long been considered the “weak link” of fixation. Surgeons must provide an environment that optimizes the ability of the cancellous bone to grow into the graft and create strong connective tissue attachments. The fixation method must be secure enough in the first 2 months to allow the progression from mechanical fixation to biological fixation without graft elongation. There are many reasons why tibial fixation is more challenging than femoral fixation. Bone mineral density (BMD) is higher in the distal femur than it is in the metaphyseal region of the tibia.1 Higher BMD provides more rigid fixation for soft tissue fixation devices such as interference screws and posts. Femoral fixation may include suspensory devices and posts that can provide more than twice the ultimate load to failure (LTF) compared with commonly used interference screws. Interference screws are more commonly used on the tibial side of the graft.2 Posts can also be used on the tibial side of the ACL graft, but this entails tying heavy sutures over the post or screw that is drilled into the tibia distal to the tunnel. The “weak link” then becomes the interface between the tendons and the sutures. When posts are used for femoral fixation, the grafts are draped over the posts and fail due to the post pulling through the cancellous bone. Tibial fixation is also more difficult because the reconstructed ACL forces are parallel to the tibial tunnel,3 requiring

either a fixation point orthogonal to the tunnel (screw or WasherLoc distal to the tunnel) or an inner-tunnel fixation device that will provide enough wedge fit and compression to secure the graft from slippage and failure under cyclical loading. When inner-tunnel fixation or interference screws are used, they are inserted in a direction opposite to the tension being pulled on the ACL graft, which may squander valuable tension.4 This, coupled with management and equal tensioning of four separate whipstitched tendons, makes tibial fixation technically difficult. Potential pitfalls in fixation include graft malposition, slippage or micromotion, tunnel widening, and lengthening of the graft after it has been positioned within the knee. We describe here 10 tibial fixation techniques that significantly improve fixation of hamstring grafts for ACL surgery. All techniques are used in all of our ACL reconstructions.

CHAPTER

TECHNIQUE 1: GRAFT PREPARATION Whipstitch each tendon strand along the entire length of the part of the tendon that is occupying the tibial tunnel. Hamstrings can be harvested one of several ways. Many surgeons harvest the semitendinosus and gracilis tendons by making an incision between the tendons as they insert on the pes anserinus. The tendons are then retrieved proximally, where they are more distinct from each other. Extra length may be achieved by using

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Anterior Cruciate Ligament Reconstruction some of the periosteum near the anterior crest of the tibia where the tendons attach.5 An equally popular way to harvest the hamstrings involves making a horizontal incision over the superior margin of the gracilis tendon, starting at the tibial crest and extending 2 to 3 cm medially. This is followed by an incision along the anterior margin of the tibia, creating a trapdoor by which the pes anserinus is reflected from the periosteum. The semitendinosus and gracilis tendons are easily visualized and dissected from the sartorius fascia. This technique better preserves the sartorius fascia that acts as a scaffold for later hamstring tendon regeneration. It also allows better visualization of the infrapatellar branch of the saphenous nerve, which is important to protect while harvesting hamstrings and performing meniscus repair. A provisional heavy nonabsorbable suture is passed several times through the end of the semitendinosus tendon to use for traction as the tendon is freed of soft tissue attachments and eventually stripped from its muscle belly. This traction suture is removed by an assistant, who then prepares the graft with whipstitches. If an assistant is not available, one can whipstitch the tendon prior to stripping while it is still attached to the muscle. A 6-inch curved Kelly clamp is used to hold the very tip of the tendon as a #2 Ethibond or orthocord suture is whipstitched up one side of the tendon and then down the other. Once the tendon ends have been secured with the traction suture or the whipstitch configuration, the suture and tendons are fed into a stripper with a circumferential opening. The stripper is gently advanced in line with the semitendinosus tendon and muscle. A slight figure-four position with the knee bent to 90 degrees may facilitate passage of the stripper. If resistance is encountered, the stripper is removed and the tissue around the tendon is probed for soft tissue attachments. The most commonly encountered adhesions are the attachments from the medial head of the gastroc tendon. Once these are released, the stripper is advanced again. The semitendinosus, being the broader and longer of the two tendons, is harvested first. Most surgeons harvest in this order in case the stripper accidentally damages the tendon that is not being stripped. Another potential reason for harvesting the semitendinosus first is the possibility that the semitendinosus may be long enough to be quadrupled, providing all four strands of the reconstruction. Preservation of the gracilis tendon may protect knee flexion strength; however, this is controversial.6 The gracilis is harvested in the majority of our ACL reconstructions. After tendon harvest, the sartorius fascia and pes anserinus are repaired to their origins using a #1 Vicryl suture. This protects the majority of the sartorius fascia from inadvertent destruction during tibial tunnel reaming. Gracilis and semitendinosus grafts are gently removed of their musculotendinous muscle attachments using a small key elevator. A #2 212

Ethibond or orthocord nonabsorbable suture is used to whipstitch each of the four arms of the tendon grafts. Usually, a running whipstitch up and down each side of the strand provides enough security for later tensioning. Occasionally one end of the graft may not have robust-enough tissue, and a locking whipstitch can be used as described by Krackow.7 Graft tunnels are measured accurately, and whipstitches are made along each arm of the four bundled graft such that the whipstitches will extend up the entire distance of the tibial tunnel (Fig. 30-1). By using whipstitches along the entire length of the graft that is occupying the tibial tunnel, fixation pullout is increased by approximately 15%.8 The tendons are then placed over a suture and drawn through an appropriately sized soft tissue guide or measuring device to determine the width of the tunnels.

TECHNIQUE 2: PRETENSION AND CYCLING OF THE GRAFTS Tendons, when at rest, are in a crimped, wavy state. When tensioned, the fibers line up in a parallel fashion and the tendon elongates by 2% to 4%, depending on where the tensioning is taking place on the stress–strain curve. Once the “toe” region of the stress–strain relationship curve has been exceeded, any further stress makes the graft stiffer and therefore makes the knee tighter.9 By preloading the graft and tensioning with 30 lb over 3 dozen cycles and/or 30 minutes of time, the graft is stiffened and the relaxation that occurs immediately after fixation is reduced (Fig. 30-2) Grafts inserted after pretensioning and cycling are much stiffer than grafts that have not undergone this technique. By placing a stiffer graft and using stiffer fixation, less load

FIG. 30-1 Whipstitches extend up the entire distance of the tibial tunnel.

FIG. 30-2 Preloading the graft by tensioning 30 lb for 20 minutes or 3 dozen cycles under tension after implanting increases graft stiffness and performance significantly.

Tibial Fixation for Anterior Cruciate Ligament Hamstring Grafts: 10 Techniques that Improve Fixation can be placed on the graft, ultimately resulting in a tighter knee.10 Recently, static tensioners have been developed to tension the graft while it is already fixed in the femoral tunnel. As the knee is cycled with the grafts under tension, the graft elongates and the grafts are retensioned prior to insertion of the interference screws.11 When using a static tensioner, we place no more than 15 lb on the graft, to be distributed equally among the four arms of the four-bundle graft (Fig. 30-3). Yasuda et al tested their ACL hamstrings grafts tensioned to 20N and 80N at the time of surgery, 2 years later the grafts tensioned at 20N had significantly more laxity than the 80N group: 2.2 mm versus 0.6 mm, respectively.12 However, it is important to remember that grafts continue to elongate despite pretensioning. A recent study demonstrated that the viscoelastic properties of tendons cannot be completely eliminated. Hamstring and anterior tibialis allografts underwent no preconditioning, cyclical preconditioning, or isometric preconditioning, and the tension of the grafts was measured over 1 hour. The grafts continued to elongate for the entire 60 minutes. In all groups the grafts lost approximately 60% of their original tension over the 1-hour period.13 This has important implications for hamstring reconstruction physical therapy protocols. We recommend and the literature supports a less aggressive regimen in the first 2 months after reconstruction.

TECHNIQUE 3: MAXIMIZE LENGTH OF THE TIBIAL TUNNEL Increasing the length of the tunnel maximizes the surface area available for healing of tendons to bone. It also provides more room for a longer fixation device and therefore improved fixation. In a dog model, pullout strength of a soft tissue

FIG. 30-3 Static tensioner.

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tendon was 153.7N in a 1-cm tunnel versus 265.5N in a 2-cm tunnel.14 However, the important healing itself occurs in the first 8 to 10 mm of the proximal tibial tunnel, and thus tibial healing is not enhanced by longer tunnels. Longer tunnels allow longer interference screws, which provide more rigid fixation when using interference screw techniques. In addition to using longer tunnels, the author’s clinic undersizes the tibial tunnel by 1 mm, allowing for a better press fit. This also enhances healing of the graft in the tunnel. Location of the tibial tunnel is extremely important in terms of neutralizing rotation (pivot-shift) and preventing early failures due to impingement. If the tunnel is too anterior in the sagittal plane, the risk of impingement is high and the graft may stretch out because it is too tight in flexion. If the graft tunnel is too posterior, it will fail to neutralize anterior translation of the tibia when the knee is in full extension.15 We currently use a high-angle tibia guide designed by Dr. Steve Howell. The guide is designed to place the tibial tunnel into a position in which impingement on the hamstring graft cannot occur. The guide directs the guide pin into the tibia at approximately 65 degrees.16 The guide has a wide, golf club (driver)–shaped tip that is inserted into the notch, and the knee is taken into full extension. The bulky tip of the guide is forced posterior in relation to the anterosuperior edge of the femoral notch. This ensures that the graft will stay behind Blumensaat’s line when the knee is in full extension, eliminating anterior impingement on the graft. The high angle created by the guide also creates a longer tibial tunnel that will enable more surface area for fixation and healing.17 In our technique, we perform only a lateral wall notchplasty and only enough to allow safe graft passage. There must be enough room between the posterior cruciate ligament (PCL) and the lateral wall for the large diameter of the Howell guide. Once there is enough room for the tip of the guide, the knee is brought into full extension. A Kirschner wire (K wire) is placed through the arm of the guide in order to align the guide to a 45-degree angle in relation to the tibial plateau. This prevents the graft from being placed in a too-vertical position. ACL grafts that are too vertical have more rotational instability and tend to pivot-shift after reconstruction.18 After the guide pin is placed in the proximal tibia, we check its position in the posterior aspect of the ACL footprint. Other landmarks that are used to check position are the anterior horn of the lateral meniscus, the PCL, and the medial tibial intercondylar eminence.19 The most useful of these landmarks is the PCL. Our pin should be within 5 to 6 mm of the anterior border of the PCL. When using this guide, one should pay close attention to the position of the guide pin as it enters the tibia. It is usually more posterior than in traditional placement techniques that aim for the midpoint between the anterior and posteromedial aspect of the tibia. Often the guide pin is very close to the anterior border of 213

Anterior Cruciate Ligament Reconstruction the superficial medial collateral fibers. If the guide pin sits within the fibers of the medial collateral ligament, then a more traditional location for the tunnel should be used to avoid damaging the ligament. Traditionally surgeons have reamed with a broad, cannulated reamer. We use a trephine bone harvesting system, also known as a coring reamer.20 This creates a long bone dowel or plug that is later used as bone graft in the tibial tunnel (discussed later). Matching the tunnel size to the graft size is very important. Steenlage et al showed that even a 0.5-mm difference in tunnel sizes could reduce ultimate LTF of tibial fixation from 308N to 221N.21 We make sure that our hamstring grafts fit snugly in their tunnels. Sometimes we even undersize the tibial tunnel by 0.5 to 1.0 mm to enhance this fit. Cain et al tested hamstring grafts in tunnels that were reamed to the correct size versus tunnels that were under-reamed by 2 mm and then dilated by smooth dilators to the same diameter as the controls. The pullout strength of the dilated group was 616N versus 453N for the reamed-alone group.22

TECHNIQUE 4: LIMITED DÉBRIDEMENT OF ARTICULAR EDGE OF TIBIAL TUNNEL After reaming is complete, there are usually small pieces of bone and cartilage debris present near the opening of the tibial tunnel into the knee joint. We remove any pieces that might cause tearing of our graft by placing the shaver up the tibial tunnel. The posterior edge of the tunnel concerns us the most. Rarely do we débride the anterior aspect of the tunnel. By débriding only the necessary pieces of articular cartilage and bone, we preserve valuable soft tissue that can help form the seal between the joint and the tunnel, which can accelerate healing.

was at the most distal aspect of the tibial tunnel.25 The insertional torque at the distal aspect of the tunnel measured 8.7 inches per pound versus 4.7 and 4.3 inches per pound in the middle and proximal thirds of the tibial tunnel, respectively. This relates directly to pullout strength and further justifies a fixation point close the cortex of the tibia. We prefer a short, broad interference screw that provides good fixation at the distal aspect of the tibial tunnel. This allows the graft to heal in the proximal aspect of the tibial tunnel without the disturbance of an interference screw. This also provides space in the proximal aspect of the tunnel for bone graft material.

TECHNIQUE 6: BONE GRAFTING OF TIBIAL TUNNEL The author has bone grafted the tibial tunnel using autograft and allograft bone for the past several years. By impacting bone between the tendons to the proximal portion of the tibial tunnel, the healing of the graft to the tunnel is enhanced in a circumferential way. As mentioned earlier, the trephinated reamer produces an excellent core of cancellous bone. This also increases pullout strength significantly.19 The bone graft is placed in the tibial tunnel prior to placing the interference screw (Fig. 30-4). The interference screw then further compacts the graft and pushes it into the proximal portion of the tibial tunnel. The surgeon must exercise care so as not to push bone into the joint itself. The only way to ensure that bone has not been pushed into the joint is to insert the arthroscope back into the knee and visualize the graft and notch area. If trephinated reamers are not available, one can use allograft bone chips or OBI bone substitute (Osteobiologics, San Antonio, TX).

TECHNIQUE 5: DISTAL TUNNEL FIXATION Location of the fixation device will determine the ultimate fixation strength of the ACL graft. The bone closest to the cortex of the proximal tibia has the tighter trabecular pattern and higher BMD.23 The cortex at the distal aspect of the tibial tunnel provides better fixation than the cancellous middle portion of the tibial tunnel. The very proximal part of the tunnel can provide good fixation, but the fixation device should not interfere with bone completely encompassing the graft. This must be balanced with the knowledge that fixation points farther away from the joint may produce more tunnel widening.24 In theory, this may hinder bone attachment to the hamstring tendons. Phillips et al demonstrated in human cadavers that the greatest amount of screw insertional torque 214

FIG. 30-4 Bone graft placed in the tibial tunnel prior to fixation.

Tibial Fixation for Anterior Cruciate Ligament Hamstring Grafts: 10 Techniques that Improve Fixation

TECHNIQUE 7: RIGID INTEROSSEOUS COMPRESSION WITH INTERFERENCE SCREW The goal of any fixation should be to limit motion as much as possible. Rigid fixation creates an environment in which bone healing to the tendons is more likely to occur. Interference screws when used with a protective sleeve can provide this rigid fixation (i.e., IntraFix, Mitek, Norwood, MA). The IntraFix has several advantages over other fixation devices (Fig. 30-5). The sleeve protects the graft from laceration during insertion while at the same time pressing the four hamstring strands firmly into the cancellous bone of the tibia. If two assistants are available, we prefer to have the arms of the graft pulled in the direction of the tunnel, and then without losing tension, we lay the grafts down on the edge of the tibia in four separate directions. The tunnel is first expanded with the IntraFix expander. We then place our bone graft in the tunnel and again use the expander to ensure that there is enough room for the sleeve and screw. The grafts are again pulled in the direction parallel to the tunnel and the grafts are laid down in opposite directions on the tibia, similar to the spokes on a wheel. The sleeve is inserted, followed by the screw. The screw is advanced until it is nearly flush with the tibia. Further advancement past the cortical bone will sacrifice fixation strength, as explained earlier. The author’s clinic purposely use an interference screw that is equal to or larger than the diameter of the tunnel drilled for the graft. We typically use the shorter of the two screws to ensure that our interference screw does not “interfere” with bone healing to tendon near the joint surface.

FIG. 30-5 IntraFix device (Mitek Products, Norwood, MA).

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Kousa et al tested six different tibial fixation devices in human cadavers.4 The study included two screw-and-washer fixation devices and four interference screw devices including IntraFix. Single-cycle LTF testing as well as 1500-cycle load testing were performed on the specimens. IntraFix had the highest single-cycle LTF threshold at 1332N, which was 357N stronger than the next closest device, the WasherLoc (975N). After cyclical load testing, the residual displacement of the IntraFix averaged 1.5 to 0.3 mm, which was the lowest displacement of the six devices. WasherLoc had 3.2 to 1.5 mm of residual displacement, which was the next-best recorded value.

TECHNIQUE 8: CROSS-PIN FIXATION OF INTERFERENCE SCREW SYSTEM Early failure of the soft tissue graft to cycling occurs when the interference screw and/or fixation device slips or loosens. The author has described and tested a bioabsorbable Interlock pin (Stryker Orthopedics, Kalamzoo, MI) that is constructed with polylactic acid (PLA).26 After the IntraFix device is deployed, a hole is drilled through the cortex of the proximal tibia and perpendicular to the long axis of the bioabsorbable interference screw. The smooth PLA pin is placed across the bone and the interference screw (Figs. 30-6 and 30-7). This prevents early slippage and improves fixation by as much as 30% when tested by cyclical pullout.27 By placing an

FIG. 30-6 The smooth polylactic acid (PLA) pin is placed across the bone and through the fixation screw to increase resistance to cycling stresses.

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Anterior Cruciate Ligament Reconstruction

FIG. 30-7 Rigid fix device.

Interlock pin perpendicular to the interference screw, the need for an extracortical fixation device is obviated. This also prevents reoperation in a significant number of cases wherein extracortical devices protrude and create palpable tenderness and/or kneeling pain (see Fig. 30-2).

TECHNIQUE 9: UTILIZATION OF BIOABSORBABLE MATERIALS Within the past few years, the author’s clinic has adopted bioabsorbable materials that have been enhanced for bone ingrowth. Several products have been introduced to the market that use either hyaluronic acid and/or phosphorus products embedded or molded into the poly-l-lactic acid (PLLA) device to enhance bone healing and device absorption. (Biosteon, Stryker Endoscopy, San Jose, CA, and Milagro, Mitek Products, Norwood, MA). By the use of these materials, tunnel widening should be minimized and there should be direct bone replacement of the device and the graft itself. Although bioabsorbable screws have been well studied in patellar tendon ACL reconstructions, there is relatively less information about the devices in hamstring ACL reconstructions. Bioabsorbable screws have been compared with titanium screws human cadavers and hamstring ACL reconstructions. Brand et al demonstrated that there was no statistical difference in pullout strengths between the metal versus bioabsorbable screws.28 On the femoral side of fixation, they did observe a much higher rate of graft laceration with the titanium screws. Robinson et al evaluated bone tunnel enlargement with PLLA screws versus screws mixed with PLLA and hydroxyapatite (HA).29 Tunnel widening was observed in 29.9% of the combined PLLA/HA versus 46% in the group with PLLA alone.

TECHNIQUE 10: MODIFIED PHYSICAL THERAPY FOR THE FIRST 2 MONTHS AFTER SURGERY The first 8 to 12 weeks after hamstring ACL reconstruction are the most important in terms of forming bonds between the bone and the hamstring tendons. From our knowledge 216

of what happens to grafts in vitro, we discourage any physical therapy activity that will aggressively cycle the graft. However, we do allow early weight bearing with a hinged brace as well as full range of motion as soon as possible. Stationary bicycling is not allowed until the ninth postoperative week. In a cohort study, Hantes et al demonstrated that early motion after hamstring ACL reconstruction resulted in an average of 48.14% tunnel widening versus 24.47% widening in patients with delayed motion.30 We do not allow our patients to take antiinflammatory medications postoperatively because we believe these may disrupt healing of bone to tendon in the tibial tunnel.

References 1. Brand JC Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertional torque. Am J Sports Med 2000;28:705–710. 2. Brown CH Jr, Wilson DR, Hecker AT, et al. Graft-bone motion and tensile properties of hamstring and patellar tendon anterior cruciate ligament femoral graft fixation under cyclic loading. Arthroscopy 2004;20:922–935. 3. Malek MM, DeLuca JV, Verch DL, et al. Arthroscopically assisted ACL reconstruction using central third patellar tendon autograft with press fit femoral fixation. Instr Course Lect 1986;45:287–295. 4. Kousa P, Jarvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial side. Am J Sports Med 2003;31:182–188. 5. Pagnini MJ, Warner JP, O’Brien SO, et al. Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565–571. 6. Carofino B, Fulkerson J. Medial hamstring tendon regeneration following harvest for anterior cruciate ligament reconstruction: fact, myth, and clinical application. Arthroscopy 2005;21:1257–1265. 7. Krackow KA, Thomas SC, Jones LC. A new stitch for ligament-tendon fixation. J Bone Joint Surg 1986;68A:764–766. 8. Paulos LE, Ellis B. ACL fixation pullout studies. Orthopedic Biomechanics Institute. Salt Lake City, 1998. 9. Kannus P, Jozsa L, Jarvinen M. Basic science of tendons. In Garrett WE, Jr, Speer KP, Kirkendall DT (eds). Principles and practice of orthopaedic sports medicine. Philadelphia, 2000, Lippincott, Williams & Wilkins, pp. 21–37. 10. Vachtsevanos JG, Lamberson KA, Paulos LE. Anterior cruciate graft tensioning. Tech Knee Surg 2003;21:125–136. 11. Paulos L. Personal communication, 2007. 12. Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Autogenous double hamstring tendons connected in series with polyester tapes. Am J Sports Med 1997;25:99–106. 13. Nurmi JT, Kannus P, Sievanen H, et al. Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction and after screw insertion. Part 2: effect of preconditioning on graft tension during and after screw insertion. Am J Sports Med 2004;32:418–424. 14. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of tendon-bone tunnel complex. A biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 15. Fineberg MS, Zarins B, Sherman OH. Practical considerations in anterior cruciate ligament replacement surgery. Arthroscopy 2000;16:715–724. 16. Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft (an in vitro study). J Bone Joint Surg 2006;85A:1018–1029.

Tibial Fixation for Anterior Cruciate Ligament Hamstring Grafts: 10 Techniques that Improve Fixation 17. Cuomo P, Edwards A, Giron F, et al. Validation of the 65 degrees Howell guide for anterior cruciate ligament reconstruction. Arthroscopy 2006;22:70–75. 18. Lee MC, Seong SC, Jo H, et al. Outcome of anterior cruciate ligament reconstruction using quadriceps tendon autograft. Arthroscopy 2004;20:795–802. 19. Jackson D, Gasser S. Tibial tunnel placement in ACL reconstruction. Arthroscopy 1994;10:124–131. 20. Howell SM, Roos P, Hull ML, et al. Compaction of a bone dowel in the tibial tunnel improves the fixation stiffness of a soft tissue anterior cruciate ligament graft: an in vitro study in calf tibia. Am J Sports Med 2005;33:719–725. 21. Steenlage E, Brand JC Jr, Johnson DL, et al. Correlation of bone tunnel diameter with quadrupled hamstring graft fixation strength using a biodegradable interference screw. Arthroscopy 2002;18:901–907. 22. Cain EL, Phillips BB, Charlebois SJ, et al. Effect of tibial tunnel dilation on pullout strength of semitendinosis graft in anterior cruciate ligament reconstruction. Orthopedics 2005;28:779–783. 23. Klein SA, Nyland J, Caborn DN, et al. Comparison of volumetric bone mineral density in the tibial region of interest for ACL reconstruction. Surg Radiol Anat 2005;27:372–376.

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24. Fauno P, Kaalund S. Tunnel widening after hamstring anterior cruciate ligament reconstruction is influenced by the type of graft fixation used: a prospective randomized study. Arthroscopy 2005;21:1337–1341. 25. Phillips BB, Cain EL, Dlabach JA, et al. Correlation of interference screw insertional torque with depth of placement in the tibial tunnel using a quadrupled semitendinosus-gracilis graft in anterior cruciate ligament reconstruction. Arthroscopy 2004;20:1026–1029. 26. Berg TL, Paulos LE. Endoscopic ACL reconstruction using Stryker Biosteon cross-pin femoral fixation and Interlock cross-pin tibial fixation. Surg Technol Int 2004;12:239–244. 27. Stryker Endoscopy data, 2002, Study performed by Frontier Biomedical. Logan, UT. 28. Brand JC Jr, Nyland J, Caborn DN, et al. Soft-tissue interference fixation: bioabsorbable screw versus metal screw. Arthroscopy 2005;21:911–916. 29. Robinson J, Huber C, Jaraj P, et al. Reduced bone tunnel enlargement post hamstring ACL reconstruction with poly-l-lactic acid/hydroxyapatite bioabsorbable screws. Knee 2006;13:127–131. 30. Hantes ME, Mastrokalos DS, Yu J, et al. The effect of early motion on tibial tunnel widening after anterior cruciate ligament replacement using hamstring tendon grafts. Arthroscopy 2004;20:572–580.

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PART F FIXATION DEVICES AND METHODS OF SOFT-TISSUE GRAFT FEMORAL FIXATION SUB PART I SUSPENSORY CORTICAL

Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation

CHAPTER

Chadwick C. Prodromos

INTRODUCTION The Endobutton (EB) is the most widely used femoral fixation device worldwide that is designed specifically for soft tissue grafts. Pioneered by Dr. Thomas Rosenberg and introduced around 1990, it was the first device specifically designed to hold soft tissue grafts. As originally designed, the surgeon would tie a Dacron tape connecting the button to the tendon. In the past 5 years, this technique has been largely supplanted by use of the EB-CL (continuous loop), which obviates the need to tie knots. Due to the longevity of the device, there is a much greater literature concerning it than any of the other newer, soft tissue–specific devices.

BIOMECHANICS Numerous studies have analyzed the pullout strength and stiffness of this device.1–7 Much was made at one point about a so-called “bungee effect,” in which the device’s fixation on the cortex and not in the tunnel supposedly resulted in lower stiffness. However, it has subsequently been shown that the greater stiffness resulting from cortical anchorage dwarfs the slightly reduced stiffness from the greater length of the construct.7 Also, as described elsewhere in the text, stiffness has no bearing on ultimate stability. This is because the stiffness of all grafts is independent of their mode of fixation once tunnel healing has occurred at about 2 months postoperatively. After this time, load is borne by the healed fibers that connect the 218

graft to the tunnel, not by the device. Because the fixation device is not load bearing after this time, its stiffness is irrelevant. However, even before that time, stiffness is less important because the stiffness represents only elastic deformation of the graft. It is only plastic deformation, not elastic deformation, that will result in greater ultimate clinical laxity. In fact, reduced stiffness, or greater elasticity, in the graft-fixation construct will diminish the forces that tend to displace the fixation device in cyclical loading. This reduction in stiffness diminishes these forces by partially dissipating them in temporary elastic deformation of the graft. Therefore, ultimately, stability may actually be enhanced by protecting the construct from plastic deformation or fixation device slippage while tunnel healing is occurring.

CLINICAL RESULTS In the largest meta-analysis of anterior cruciate ligament reconstruction (ACLR) autografts, the EB-hamstring combination was found to have the highest stability rates of any graft-fixation construct when paired with modern tibial fixation.8–14 Morbidity has been minimal.15–18 In our experience,8 the EB has proven to be extremely reliable. After 13 years of continuous use, as well as follow-up of more than 80% of all implanted EBs, we have had no graft failures (see Chapter 69). Approximately 86% of grafts have had IKDC normal stability. We have had no hardware complications and no displaced EBs, and we have not had to remove an EB.

Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation

SURGICAL TECHNIQUE Principle The EB is a small oval button that anchors the graft against the outer femoral cortex. It is passed up from within without a second femoral incision.

Materials The EB-CL (continuous loop) is now the standard implant. It comes with fabric loops already attached to the EB in 5-mm increments, with 15 mm being the shortest. A standard ACL tray is used, although a special 4.5-mm drill bit, available only from Smith & Nephew (Andover, MA), must be used.

Femoral-Tunnel Formation

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back and make sure the location for the tunnel is satisfactory. The knee is then flexed to at least 90 degrees and usually to about 100 degrees. The pin is then reinserted into the indentation, and the tunnel is slowly drilled, taking care to stop when the resistance of cortical bone is reached. This is easily felt if the tunnel is drilled slowly and with a light touch. Cortex will usually be reached at 30 to 40 mm, as seen on the laser-marked pin.

Minimum Tunnel Length Our minimum acceptable tunnel length is 30 mm, which, when the 15-mm continuous loop length is subtracted, leaves 15 mm of graft in the tunnel. The cortex is 3 to 5 mm thick. Thus we make sure that the laser pin shows at least 27 mm inserted into the condyle before reaching the femoral cortex to ensure that the total channel length will be at least 30 mm after drilling through the cortex.

Redrilling if the First Tunnel Is too Short Principles of Femoral-Tunnel Drilling Two femoral tunnels are necessary in sequence with each other, as will be described. They are drilled transtibially. A laser-marked, long transtibial guide pin with markings every 2 mm is used to drill the femoral tunnel at a 65-degree coronal angle. It is important to drill the tunnel such that the exit is in the femoral metaphysis rather than the femoral condyle if possible so that the tunnel will have adequate length. It has recently become apparent that a femoral-tunnel entry lower down at the 10 o’clock position rather than the 11 o’clock position (for a left knee) will improve rotational stability. This lower entry will, however, also result in a shorter tunnel because the exit will tend to be from the narrower condyle, which is lower down than the wider metaphysis. To compensate for this, the knee needs to be more flexed during drilling to 90 degrees or more in order to redirect the tunnel upward toward the metaphysis. The following is our technique for femoral-tunnel formation and EB fixation.

Notchplasty We always perform a lateral notchplasty, but not roofplasty, of about 3 mm for visualization. All soft tissue should be removed from the tunnel so that the over-the-top position can be clearly seen. It should also be probed to make sure the surgeon knows where the back of the notch is.

Basic Technique With the leg hanging free at its usual angle of about 75 degrees, a 1-mm deep indentation is made with the tip of the drill pin at the 10 o’clock position, and about 3 mm distal to (forward from) the over-the-top position. The tunnel entry point is found in this fashion because visualization is easiest at this degree of knee flexion. We then pull the pin

If the tunnel is less than 27 mm we withdraw the pin, relax the knee to 75 degrees or so, and make a new pilot indentation at about the 10:30 position and about 5 mm distal to over-thetop position (i.e., slightly higher and more distal or forward than the original hole). We then flex the knee to 5 or 10 degrees more than on the first pass, at least 95 degrees, and redrill the hole. The new tunnel should be significantly longer. The changes in tunnel location, along with the greater knee flexion, yield longer tunnels and will still result in a tunnel in a very acceptable location. If the knee is adequately flexed the first time, however, a second pass will rarely be necessary.

Finishing the Femoral Tunnel Once a satisfactory tunnel has been found, the laser pin is further drilled through the cortex. We observe the laser markings when giving way is achieved, which indicates the pin has burst through the cortex, so we have a good idea of the total channel length. Next, the appropriate acorn reamer is inserted over the pin. This is drilled nearly to the cortex, as measured from the laser pin. If high resistance is felt before the anticipated point is reached, drilling should be stopped to avoid breaking through the opposite cortex. Generally the acorn reamer will be drilled 1 to 2 mm shorter than the laser pin length indication of where the cortex was reached. The socket will usually be about 6 mm shorter than the total channel length. It must be within 9 mm of the length of the total tunnel to allow a 15-mm EB-CL to be used. This is because at least 6 mm of extra length is needed to allow a turning radius for the EB as it sits outside the femoral cortex (i.e., 6 þ 9 ¼ 15 mm). Once the socket is drilled, the acorn drill bit is withdrawn and a 4.5-mm bit is inserted and drilled through the outer cortex with the guide pin still in place (Fig. 31-1). After the 4.5-mm tunnel 219

Anterior Cruciate Ligament Reconstruction multiple of 5, then the next-largest number that is a multiple of 5 is selected. For example, if the total channel is 34 mm and the socket is 27 mm, the difference would be 7 mm. 7 þ 6 ¼ 13. The next-largest number that is a multiple of 5 is 15, so a 15-mm EB-CL is selected. In this case, 34 – 15 ¼ 19, so 19 mm of graft would be in the femoral tunnel.

Preparing the Endobutton/Graft Construct

FIG. 31-1 The 4.5-mm drill bit is drilled through the cortex over the previously drilled, laser-marked, long guide pin after the socket has been drilled.

is drilled, the guide pin is removed with the 4.5-mm drill bit. Next, the long-depth gauge is used to measure the total channel length (Fig. 31-2). If it exceeds the socket length by more than 9 mm, the guide pin and then the acorn drill bit should be reinserted over the guide pin, and the socket should be drilled a little farther so that it is within 6 to 9 mm of the total length. If the far wall of the cortex is accidentally violated, this can be easily salvaged with an Xtendobutton, as will be described.

The EB-CL is positioned in the holder on the Graftmaster board. The graft is then passed through the fabric loop attached to the EB (Fig. 31-3). A violet #3–0 or 4–0 monofilament absorbable suture is then sewn across the graft (Fig. 31-4) at a distance from the EB that is 2 mm greater than the total channel length, as identified on the Graftmaster board on which the construct is positioned. In the earlier example, the total channel length was 34 mm, so the suture would be placed at 36 mm from the EB. This will provide arthroscopic evidence that the graft has been passed to the proper depth later in the procedure. This area should also be marked with a marking pin. This

Calculating Endobutton–Continuous Loop Length The socket length is subtracted from the total channel length and 6 or 7 mm are added for a turning radius. If that number is a multiple of 5, then that is the EB-CL used. If it is not a

FIG. 31-3 The prepared graft is passed through the fabric loop until each arm of the graft is the same length.

FIG. 31-2 The total channel length is measured with the long-depth gauge while viewing the femoral-tunnel entry point arthroscopically.

220

FIG. 31-4 The colored absorbable monofilament suture locks the graft to prevent sliding and also marks the entry point for the femoral tunnel.

Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation absorbable colored suture also locks the graft in place, preventing it from sliding on the fabric loop. A #5 suture is then passed through one eyehole and a #2 suture through the other eyehole of the EB. All four suture ends are then passed through the eye of the long passing pin (Fig. 31-5), and a hemostat is applied to the four suture ends near their tips to lock the graft onto the pin.

31

sure the graft cannot be pulled back out (Fig. 31-8). We then wrap the sutures around the smooth shank of the tibial screw and hold very strong tension while fully flexing and extending the knee three times. This serves to eliminate slack from the graft. Equally importantly, this will serve to pull the graft out of the knee if the EB has not been seated. For this reason,

To ta lc In ha se nn le rti ng on el th le Co ng nn th sp ect an ion

Passing the Graft The long pin with the graft and sutures attached is then passed into the tibial tunnel into the knee, where it is visualized with the arthroscope. The knee should be flexed during this passage to the same degree as when the femoral tunnel was drilled. The pin is then inserted into the femoral tunnel and passed proximalward out through a puncture in the soft tissue, where it is pulled free of the passing sutures (Fig. 31-6). Sometimes the pin must be redirected subtly within the femoral socket before it finds the smaller 4.5-mm tunnel and makes its way into the soft tissue. The two #5 sutures are then grasped with a Kocher clamp. The sutures are wound onto the closed Kocher jaws like a spool. The Kocher with wound sutures is then strongly pulled until the graft can be felt to pass into the femoral socket and become fully seated. The previously inserted violet suture and ink markings on the graft are visualized arthroscopically just outside the femoral-tunnel opening, which confirms that the graft is in proper position. If the graft is not fully seated, the Kocher can be wound like a windlass to pull in the graft. Cycling of the knee may also help.

Seating the Endobutton The two #2 sutures are then pulled to flatten the EB on the external femoral surface. After slack is taken up, a slight toggling should be felt (Fig. 31-7). Strong retrograde tension should be applied to the whipstitches as they dangle out the tibial incision while the knee is flexed and extended to make

A

FIG. 31-5 All four sutures—two #5 and two #2 sutures—are passed through the eye of the long passing pin.

FIG. 31-6 A,B, The long guide pin is passed into the knee and out through the soft tissue with the graft construct attached.

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Anterior Cruciate Ligament Reconstruction

FIG. 31-7 The #2 sutures are used to flatten the Endobutton, seating it on the femoral cortex after the graft has been pulled into the socket with the #5 sutures.

this step is very important. We have had the graft withdraw in this fashion two or three times and have successfully reseated it each time (see “Troubleshooting”). We have never had a graft pull out later. However, if this step had been omitted, later loosening could have occurred in these cases. The tibial screw or other tibial fixation method is then tightened.

Removing the Passing Sutures After the EB is flattened and tibial fixation has been applied, the passing sutures should be pulled out from the EB. The #2 suture should be tried first, making sure that it slides freely (if not, see problem 3 in “Troubleshooting”). If it does slide freely, cut one limb off at skin level, and pull the other end out and discard it. This is repeated with the #5 suture.

TROUBLESHOOTING In this section, we list all the EB problems that we have either encountered or theorized but not encountered. In all 222

cases the difficulty was dealt with, the surgery was finished with only a minor delay, and a good result was obtained. In 13 years of continuous use we have never had an EBrelated complication, EB failure, or migration. We have never had to remove an EB nor had a graft fail when fixated with an EB.8 Rarely, however, one of the following problems may arise. If the surgeon is prepared, these problems should pose no difficulty. The EB has proven to be remarkably trouble free over the most extended use of any soft tissue femoral fixation device.

Problem 1: What if the Endobutton Will not Flatten and the Graft Pulls back through and into the Knee? Cause 1 The total channel length was measured too short, and hence the EB-CL is too short, so it is not emerging outside the femoral cortex where it can be flattened.

Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation

31

FIG. 31-8 Strong retrograde tension fails to dislodge the graft when the knee is cycled once the Endobutton has been properly seated.

Comment

Comment

This is a rare occurrence that was slightly more likely to happen in the past, when tunnels were placed higher and channels were longer than at present. The lower tunnel placements currently used result in relatively short tunnels, which are easier to measure. Also, initially the long guide pin did not have laser markings. At our urging, Smith & Nephew began fabricating marked guide pins and has now included laser length markings on all long guide pins, which allows the surgeon to closely estimate the femoral-tunnel length while drilling before measuring with the depth gauge.

If this occurs, you will usually know when you burst through with the socket reamer (or at least suspect it), but it is possible to damage the cortex and not realize it until the EB will not hold.

Remedy If the EB will not flatten and seat and catch, it should be passed a second time. If it still will not seat, then the femoral tunnel should be remeasured. If a longer measurement is indeed obtained, a longer EB-CL should be attached, and the EB should now flatten and catch appropriately. If the total channel was measured accurately and if the difference between the total channel length and the socket is 8 or 9 mm such that the turning radius of the EB is only 6 or 7 mm, then the socket should be drilled another 2 or 3 mm if possible. This allows a greater turning radius for the EB of 8 to 10 mm and should facilitate seating.

Remedy 1 A second incision of 3 cm in length near the exit of the femoral tunnel can be made. A #5 suture can be substituted for the #2 suture and tied 2
2 with the other already inserted #5 suture around a 6.5-mm, two-thirds threaded unicortical cancellous screw and washer inserted about 1.5 cm away from the exit of the femoral tunnel. Remedy 2 Currently, this problem could be more easily salvaged without a second incision by attaching the larger, recently introduced Xtendobutton to the EB and then passing the graft again. This larger button will hold in a socket-sized larger tunnel up to at least 10 mm. The surgeon should make sure an Xtendobutton is present at surgery in case it is required.

Cause 3 The two passing sutures are tangled.

Cause 2

Comment

The lateral cortex was damaged by the socket reamer, effectively enlarging the 4.5-mm tunnel such that the EB does not hold and falls back into the joint.

When the graft is pulled back, the entanglement that prevents the thinner flattening suture from functioning should be clearly visible arthroscopically. 223

Anterior Cruciate Ligament Reconstruction Remedy Separate the #5 and #2 sutures from each other, and pass the graft again without withdrawing the sutures from their exit out of the thigh.

Problem 2: What if the Endobutton Flattens Initially but Is Pulled Back out when the Graft is Tensioned? Cause 1

Problem 4: What if the Endobutton-CL Is so Long that There Is too Little Graft in the Femoral Tunnel?

Excessive tensioning pressure was applied to the graft on the tibia, and the EB was pulled back without apparent cause.

Cause

Comment

Mismeasurement of the tunnel or miscalculation with selection of an EB-CL that is too long.

We have had this occur on only one occasion for no apparent reason, except that we were probably excessively tensioning the graft during range of motion of the knee prior to tying around the tibial screw. There was a palpable “thunk” when it happened, as though a minor knee subluxation had taken place. We then noticed mild slack on the construct and slight withdrawal arthroscopically. Remedy Repass and flatten the EB. If it holds, as it did during our case, take a radiograph before applying tibial fixation with fluoroscopy to make sure the position is satisfactory. If so, proceed to finish tibial fixation. Nothing further needs to be done, although we would recommend a repeat radiograph at 3, 7, and 14 days postoperatively to verify EB position. Repeat radiographs in our clinic showed no migration, and excellent stability ultimately resulted.

Cause/Remedy 2 See Problem 1, Cause 2.

Problem 3: What if the Passing Sutures cannot be Pulled out of the Endobutton After Fixation? Cause Entanglement or entrapment in soft tissue. Comment This is less likely to happen if the knee is flexed to the same degree for passing suture removal as during graft passage. Remedy The surgeon should slide one of the passing sutures a few millimeters to make sure it is free. If it will not slide one way easily, it often will do so in the opposite direction. If it still will not slide, the soft tissue of the thigh should be compressed 224

downward and the ends cut. The recoil of the soft tissue will ensure that the ends retract well below the dermis. We have had this happen once. No sequela occurred as a result of the suture being left in the soft tissue. We prefer this to forcing the suture to come out, which we fear might displace the EB into the tunnel.

Comment We have never had this happen, but the surgeon should be prepared in case it does occur. Remedy Even if there were less graft in the tunnel than we had planned, we would leave it alone if there were at least 15 mm of graft in the tunnel. Studies19,20 and the experience of ourselves and others have shown this to be adequate. If less than 15 mm were in the tunnel and the fabric loop were visible through the arthroscope, we would recommend cutting the loop arthroscopically and then using the 4.5-mm bit to push the EB outward into the soft tissue. The tunnel would then be remeasured, and another EB-CL of more appropriate length would be used. If the fabric loop were not visible arthroscopically or could not be cut and if less than 15 mm of graft were in the tunnel, we would make a small second incision to either remove the EB or feed it back into the tunnel so that it could be removed from below. We would then remeasure the tunnel and use an appropriately shorter EB so that satisfactory graft remained in the tunnel.

Problem 5: What if the Far Femoral Cortex Is Blown out with the Socket Reamer such that a 4.5-mm Tunnel Cannot Be Drilled? See Problem 1, Cause 2. Problem 5 is the same problem but with earlier recognition that it has occurred.

THE XTENDOBUTTON Recently released, the Xtendobutton is a larger button that attaches to the standard EB (Fig. 31-9), effectively enlarging its profile as described earlier. It can be used routinely to eliminate the need to drill the narrower 4.5-mm tunnel. This larger profile can be used with larger tunnels up to at

Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation

31

continuous use. However, it is likely that the use of the Xtendobutton will prove to be just as reliable. Xtendobutton use eliminates the calculations involved with two tunnels, which may facilitate the procedure for the occasional user. As described earlier, the Xtendobutton is of great value if the surgeon penetrates out the far femoral cortex with the larger socket reamer such that the standard EB is too small to use. Before the introduction of the Xtendobutton a second incision would have had to be made over the femur for insertion of a femoral screw. The Xtendobutton allows the procedure to be completed in the usual fashion without a second femoral incision (Fig. 31-10).

FIG. 31-9 The Xtendobutton fits over the Endobutton so that it is large enough to hold outside a 10-mm femoral tunnel.

least a 10-mm tunnel. We still use the smaller 4.5-mm tunnel in conjunction with the larger socket because we believe the smaller bone removal may be beneficial and because we are comfortable with this technique after 13 years of

CONCLUSIONS 1 Stability: Unsurpassed stability rates have been reported using the EB. 2 The bungee effect: The bungee effect is either nonexistent or clinically insignificant.

FIG. 31-10 In this revision case, the Xtendobutton was used to anchor the graft on the outside of a 9-mm femoral tunnel.

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Anterior Cruciate Ligament Reconstruction 3 Technique: The most important technical point is to flex the knee to or beyond 90 degrees during femoral-tunnel drilling to ensure a tunnel of at least 30 mm in length. 4 Morbidity: The complication rate has been virtually nonexistent, with only a few reported cases (and none in our experience), despite the highest level of use of any noninterference screw femoral fixation device. 5 Xtendobutton: The Xtendobutton provides salvage without making a femoral incision if the far cortex is blown out. It also simplifies the procedure for the occasional user. 6 Ease of use: The method is straightforward and easily learned.

References 1. Ahmad CS, Gardner TR, Groh M, et al. Mechanical properties of soft tissue femoral fixation devices for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:635–640. 2. Brand J Jr, Weiler A, Caborn DNM, et al. Graft fixation in cruciate ligament surgery. Am J Sports Med 2000;28:761–774. 3. Brand J Jr, Hamilton D, Selby D, et al. Biomechanical comparison of quadriceps tendon fixation with patellar tendon bone plug interference fixation in cruciate ligament reconstruction. Arthroscopy 2000;16:805–812. 4. Brown CH, Wilson DR, Hecker A, et al. Comparison of hamstring and patellar tendon femoral fixation: cyclic load. Presented at the 1999 Meeting of the American Orthopaedic Society for Sports Medicine, Traverse City, MI, June, 1999. 5. Rowden NJ, Sher D, Rogers GJ, et al. Anterior cruciate ligament graft fixation: initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers. Am J Sports Med 1997;25:472–478. 6. Scheffler SU, Sudkamp NP, Gockenjan A, et al. Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: the impact of fixation level and fixation method under cyclic loading. Arthroscopy 2002;18:304–315. 7. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387.

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8. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 9. Gobbi A, Mahajan S, Zanazzo M, et al. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation in athletes. Arthroscopy 2003;19:592–601. 10. Gobbi A, Tuy B, Mahajan S, et al. Quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a clinical investigation in a group of athletes. Arthroscopy 2003;19:691–699. 11. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 12. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 13. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20:1015–1025. 14. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 15. Karaoglu S, Halici M, Baktir A. An unidentified pitfall of Endobutton use: case report. Knee Surg Sports Traumatol Arthrosc 2002;10:247–249. 16. Simonian PT, Behr CT, Stechschulte DJ Jr, et al. Potential pitfall of the Endobutton. Arthroscopy 1998;14:66–69. 17. Muneta T, Yagishita K, Kurihara Y, et al. Intra-articular detachment of the Endobutton more than 18 months after anterior cruciate ligament reconstruction. Arthroscopy 1999;15:775–778. 18. Brucker P, Zelle BA, Fu FH. Intraarticular Endobutton displacement in anatomic anterior cruciate ligament double-bundle reconstruction: a case report. Op Tech Orthop 2005;15:154–157. 19. Zantop T, Brucker P, Bell K, et al. The effect of tunnel-graft length on the primary and secondary stability in ACL reconstruction: a study in a goat model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 20. Yamazaki S, Yasuda K, Tomita F, et al. The effect of intraosseous graft length on tendon-bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 2006;14:1086–1093.

Cortical Screw Post Femoral Fixation Using Whipstitches, Fabric Loop, or Endobutton: The Universal Salvage BACKGROUND

biomechanically preferable, and more two-incision methods are now being described.

32 CHAPTER

Chadwick C. Prodromos

Importance We believe that every surgeon performing anterior cruciate ligament reconstruction (ACLR) would benefit by being able to perform at least one of the variants of cortical screw post femoral fixation described here. Although probably not their primary techniques, they are the universal “bail-out” methods for rescuing more exotic and complicated single-incision techniques gone awry on the femoral side. The ability to troubleshoot is arguably the most important skill a surgeon can possess, and these techniques not only troubleshoot all other femoral methods (and all grafts), but they also can be accomplished with materials that are present in every orthopaedic surgical suite.

History Whipstitch cortical screw post was perhaps the most popular method of soft tissue ACL graft fixation when two-incision methods were commonly used. There are many reports of high stability using this method.1–6 However, the advent of the Endobutton and then the various cross-pins that did not require a formal second incision relegated the two-incision method to a secondary role. More recently it has become apparent that a second incision for outside-in drilling can facilitate the lower femoral tunnel placement that is now recognized as

BIOMECHANICS The technique uses rigid cortical bone for anchorage. This has been shown to be the most important factor in producing high-stiffness fixation.7 The stiffness is reduced slightly by the length of the construct, but the rigidity of the cortical bone7 has been shown to more than compensate. A fabric or suture interface has been associated with high-stability ACLR,8–11 as have whipstitches if properly implanted.12–14 Both are described here in conjunction with cortical screw post fixation.

Advantages We no longer use the femoral screw post through a second incision as a primary method because we have had success using the one-incision Endobutton method. However, we still believe that the two-incision technique has a number of advantages. 1 It is useful in revision cases where singleincision techniques may be problematic or impossible. 2 It is useful in difficult primary cases, particularly those with small distal femora resulting in short femoral tunnels as a backup to single-incision techniques if the surgeon blows out the back wall. 227

Anterior Cruciate Ligament Reconstruction 3 It allows odd-numbered strand grafts such as triple semitendinosus (3ST), 3ST/1 gracilis (Gr), and 3ST/ 2Gr,2 grafts that cannot be looped as a quadruple graft with the use of cross-pins. 4 We believe that due to the small learning curve, it is a more reliable method than some complicated singleincision techniques for the surgeon who performs a small volume of ACL reconstructions. 5 It allows the most precise proximal-distal positioning of the graft in the tunnels and knee of any method. This is useful with shorter grafts where malposition in the proximal-distal direction may result in too little graft length in one of the tunnels. 6 No other fixation method has resulted in higher stability rates.2 7 Most importantly, as mentioned earlier, it can troubleshoot any problem that occurs with a femoral fixation device, femoral tunnel, or femoral graft. The only disadvantage to this technique is that it requires a second incision. However, this disadvantage is usually primarily in the mind of the surgeon. We, and others, have never found the use of a small second incision to be of concern to the patient (see Chapter 49). Furthermore, the incision does not need to be large. Some may dislike the fact that a nonbioabsorbable and nonradiolucent screw remains in the patient. However, we have never seen one of these screws back out, nor have we ever seen one bother the patient2 because the screw sits flush on cortical bone under a thick muscular layer. Plus, because they are metadiaphyseal, they are far enough from the joint to not interfere with subsequent magnetic resonance images (MRIs).

SURGICAL TECHNIQUE Materials A standard 6.5-mm, two-thirds threaded cortical screw with a smooth washer is usually used. ACL tibial fixation posts can also be used as follows: There are two 4.5-mm screws without washers with which we are familiar, one made by Smith & Nephew (Andover, MA) and one by Arthrex (Naples, FL). If these washerless screws are used, the screw must be slightly angled away from the femoral tunnel to prevent suture or fabric loop slippage. Linvatec (Largo, FL) has a good 6.5-mm screw, which is used with a washer. Arthrex also has a 6.5-mm screw that is used with a washer, but it uses a smaller (2.5-mm) hex screwdriver. In the past we had occasional instances of breakage of the smaller screwdriver when it encountered high torque with the large screw. 228

Whipstitches should be put in using either standard #5 braided, nonabsorbable polyester sutures such as Ethibond (Ethicon, Somerville, NJ), Tevdek (SybronEndo, Orange, CA), or Mersilene (Ethicon) or one of the newer stronger #2 sutures such as Fiberwire (Arthrex) or Ultrabraid (Smith & Nephew). The surgeon may also pass a 5- or 6-mm Dacron tape through a quadruple graft and tie it around the cortical screw instead of using whipstitches. A 2- or 3-mm tape is not strong enough. The best loop, however, is the fabric loop that is attached to the Endobutton-CL, which comes in 5-mm increments with 15 mm being the smallest.

Incision The lateral femoral incision should be made with the knee flexed. The posterior border of the lateral femoral condyle should be palpated and the incision made over the middle of the lateral femoral metaphysis at the flare of the condyle. In a lean patient this incision is about 2 cm long. It will need to be larger in larger patients. The iliotibial band is longitudinally split, and the lateral femoral metaphysis is exposed.

Femoral Screw Insertion Technique The femoral screws should be inserted unicortically as with tibial screw posts for three reasons. 1 As mentioned earlier, we have never had one back out, so bicortical insertion is unnecessary. 2 They are cancellous screws, and if they are inserted bicortically, they may be impossible to remove later if needed. 3 Also, they can toggle if they are tied under tension before final tightening, with the tip moving slightly away from the predrilled hole in the opposite cortex. This may make it impossible for the tip of the screw to enter this hole at final tightening, resulting in the screw remaining proud and potentially irritating the patient. Unicortical insertion prevents this problem.

Attaching the Graft to the Femoral Post There are four methods by which this may be successfully accomplished, all of which we have used. We prefer number four. Numbers one and four require an Endobutton-CL to be available. If it is not available, then method two or three may be used, and both are very satisfactory.

1. Endobutton-CL Fabric Loop Passed around the Femoral Post This is the most difficult technique for properly positioning the graft, but it does have the advantage of being the only

Cortical Screw Post Femoral Fixation Using Whipstitches, Fabric Loop, or Endobutton: The Universal Salvage technique of the four described that does not require the tying of knots for those who perceive a knot as a possible weak link (which we have not found it to be). The femoral tunnel should be drilled in the appropriate location by an inside-out or outside-in technique. The 3.2-mm drill bit for the femoral screw should be drilled a distance of at least 1.5 cm from the femoral tunnel. This will result in at least a 1-cm bone bridge between the femoral tunnel and the screw when the 6.5-mm cancellous screw and smooth washer are screwed in. The screw should be angled slightly away from the femoral tunnel to further prevent the loop from slipping over the washer and screw. The two-thirds threaded screw should be advanced until all threads are buried into the femur, leaving only smooth screw shank exposed. At the back table or Mayo stand, the graft should be placed through the Endobutton-CL loop and then #5 braided nonabsorbable sutures passed through the Endobutton eyelets. These sutures are used to pass the construct through the knee and out of the femoral tunnel into plain view. The loop is passed over the screw head and washer, and the screw is tightened down. The Endobutton will lie between the screw and the femoral tunnel and will not interfere with fixation. The length of the loop should be calculated in advance to allow the graft to sit where desired in the knee in a proximal-distal direction. This must take into account the size of the bone bridge between the shank of the screw and the opening of the femoral tunnel as well as the diameter of the screw. Added to this should be the amount of length the surgeon wishes the graft to be recessed within the femoral tunnel from its outer opening. The graft should be clearly marked circumferentially before implantation at a distance of 2 cm from each end with a marking pen. As long as these marks are not visible arthroscopically the surgeon can be sure there is at least 2 cm of graft in each tunnel. The graft should also be marked with a 3-O or 4-O, violet-colored, absorbable monofilament suture that is used to tie the strands together in the middle of the graft. This suture serves the dual purpose of preventing the graft from sliding along the loop when tensioning and tibial fixation are carried out and also allows the surgeon a visible guide point for what should be the approximate intraarticular midpoint of the graft. With a long 2ST/2Gr graft this method is highly satisfactory because there is enough length to have more graft than is needed in each tunnel; usually 3 cm in each tunnel is a reasonable goal. If the measurements are off slightly after the graft is tightened down, the graft does not need to be adjusted. If the end result is too little graft in one of the tunnels by the surgeon’s standards, then the graft can be withdrawn out the tibial tunnel and passed

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through again using a shorter or longer Endobutton-CL loop. With the shorter 4ST graft this method is still usually satisfactory but requires more precision. A minimal length of 15 mm of graft in the tunnels appears to be adequate.15,16

2. Fabric Tape Tied Around the Femoral Post If a Dacron tape was used to pass the graft up into the tibial tunnel and out the femoral tunnel, it should be discarded, as it may be frayed, and a new tape should be used for fixation. The surgeon should watch the intraarticular portion of the graft on the video screen, with the assistant holding the arthroscope as the surgeon ties the 5- or 6-mm Dacron tape around the post. The tape ends should be passed once around the shank of the screw, crossed around the opposite side of the shank, and then brought back to the near side of the screw for tying. By this means the surgeon controls the proximal-distal position of the graft. The tape is tied to a length that will provide optimal lengths of tissue in each tunnel. Before the surgeon ties, the assistant should exert mild tension on the tibial end of the graft to remove gross slack from the graft, which further ensures proper positioning. The screw and washer should then be finally tightened. The graft should be marked with both a marking pin and a cross-suture near the proposed femoral aperture, as described previously.

3. Whipstitch Technique In this technique the four-strand graft, if it is used, may be made into four single strands of graft of equal length. #2 braided, nonabsorbable whipstitches are then woven into each of the eight ends as described in Chapter 42. It is of paramount importance that all the sutures are woven in very tightly with strong tension after every pass or every other pass of the suture to maximally tighten the weave so that no tightening of the weave will occur later. Again, the graft should be marked with both a marker and suture, as in method 1. The sutures are then tied, two by two, around a cancellous screw and washer (Fig. 32-1) as follows: Each double suture strand is brought up to the smooth screw shank and crossed around the far side of the screw. These ends are then pulled back and tied two by two, such that the knot is on the graft side of the screw for the first two graft limbs. The process is repeated for the other two graft limbs. This will result in two knots in the femoral post. It is important to keep track of which sutures correspond to which graft segment either by using different color sutures or marking or knotting the suture ends before passing the graft segments. 229

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FIG. 32-1 A and B, Two-thirds threaded femoral cancellous screw and washer used as fixation post for whipstitches from four-strand hamstring graft tied around it.

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4. Graft Passed Through the Endobutton-CL Loop and Sutures Used to Tie the Endobutton to the Femoral Post

Fixating Single Strands of Graft and Odd Numbers of Strands

This is our preferred technique. Rather than tying a fabric loop around a cancellous screw, the surgeon can pass the graft through a short Endobutton loop and then pass a #5 braided nonabsorbable suture through each end of the Endobutton. These sutures can then be used to tie the Endobutton (and hence the loop and graft) to the screw as described in the previous paragraph. We prefer this technique if the Endobutton-CL is available because of the known strength of the fabric loop attached to the Endobutton. It also obviates the need to put whipstitches in the femoral end. Generally the surgeon will prefer to use the shortest loop, which is 15 mm. The Endobutton will be closely juxtaposed to the screw (Fig. 32-2) but is sufficiently low in profile to allow secure attachment to the screw without being in the way. A washer should be used on the screw. Again, the graft should be marked with both a marker and suture as in method 1.

Double-length strands that are looped over a femoral fixation device are now the mainstay of autograft and allograft ACL soft tissue femoral fixation. However, single strands may also be used in combination with double strands or other single strands to fashion a variety of grafts. The goal is to have a graft of sufficient strength to provide good stability using the available tissue. Reports of excellent stability now exist for three-, four-, five-, six-, and eight-strand grafts (see Chapter 17). These variegated grafts may be used with any of the four fixation methods described earlier. For an added single strand of graft, whipstitches of braided #2 nonabsorbable suture should be implanted. Then the two ends can be tied one to one either around the Endobutton-CL fabric loop (methods 1 and 4), the Dacron tape (method 2), or the femoral screw itself (method 3).

Cortical Screw Post Femoral Fixation Using Whipstitches, Fabric Loop, or Endobutton: The Universal Salvage

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FIG. 32-2 A and B, Sutures through the Endobutton eyelets are tied around the femoral screw post. The graft is looped through the Endobutton-CL fabric loop.

Radiography We use C-arm fluoroscopy after the screw is tightened down to document its satisfactory position. Fluoroscopy is not needed during implantation. We have never found a screw to be intraarticular or otherwise malpositioned. The screw will generally lie in the distal femoral metaphysis, but it can be placed adjacent to wherever the femoral tunnel emerges on the external femoral surface.

THE FEMORAL POST TECHNIQUE CAN SALVAGE THE FOLLOWING SITUATIONS 1 Lateral cortex blowout with Endobutton fixation: Conversion is easy, and the Endobutton can still be used for fixation by taking advantage of the fabric loop. 2 Proximal tunnel wall blowout: This is not a problem for femoral cortical suspensory fixation such as the Endobutton or EZLoc but is a problem for interference fixation. It is easily remedied with the femoral post

technique, as a circumferential bone tunnel is not required. It is, however, important that the graft be pulled distalward against the distal tunnel wall and the screw be inserted distal to the exit area of the femoral tunnel. This will compress the graft against the distal wall. If the screw is put in proximal to the exit area of the femoral tunnel, the graft could potentially be pulled out of the femoral tunnel, as this tunnel is now really a “notch” and not a tunnel. 3 Revision surgery in which a new proximal tunnel partially overlaps with the old more distal tunnel: The surgeon may need to bone graft the old tunnel in this case. However, a semicircular notch in the femur (indenting in from the over-the-top position) can often be created lower down on the femur, which will produce a very biomechanically sound graft and save the patient both the pain of a bone graft and a second procedure. This tunnel may tighten a little more than usual toward extension, which should be taken into account when tensioning. 4 Fixation device breakage: The breakage or lack of availability of another device should allow conversion to one of the previously described techniques. 231

Anterior Cruciate Ligament Reconstruction 5 Harvesting a short semitendinosus or gracilis: If one tendon is cut too short during harvest to use as a loop (i.e., less than 14 cm) but the other tendon is at least 21 cm, then the longer tendon can be tripled and combined with the shorter tendon as a single strand as described earlier (i.e., the surgeon can use either a 3ST/1Gr or 1ST/3Gr). Both of these grafts are strong enough to substitute for the torn ACL, especially the 3ST/1Gr (in fact, 3ST alone should be sufficient). Because some femoral fixation systems would have difficulty with these grafts, the surgeon may use femoral screw post fixation instead, thus obviating the need to make an unplanned switch to allograft, which might otherwise be necessary.

CONCLUSIONS 1 Stability: Femoral post fixation provides unsurpassed stability. 2 Morbidity: Morbidity is minimal. The use of a second incision is necessitated; however, this is usually well tolerated by patients. Screw removal is virtually never necessary. 3 Ease of use: The method is straightforward and uses techniques familiar to every surgeon. If whipstitches are used, they must be inserted carefully and tightened maximally. 4 Equipment: Although the Endobutton-CL is useful, it is certainly not necessary. Every operating suite will have a 6.5-mm, partially threaded screw and smooth washer and #5 braided nonabsorbable sutures, and probably 5- or 6-mm Dacron tape as well. Also, 4.5-mm cancellous screws with washer can be used with care. 5 The universal salvage: In the increasingly complex world of ACLR in which high-tech techniques can go awry, it is a great comfort to have the ability to perform this technique, which can salvage virtually any ACLR-related problem on the femoral side.

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References 1. Prodromos CC, Joyce BT. In Five-strand hamstring ACL reconstruction: a new technique with better long-term stability than four-strand. Presented at the 2006 meeting of the Mid-America Orthopaedic Association, San Antonio, TX, April, 2006. 2. Prodromos CC, Joyce BT. In Five-strand hamstring ACL reconstruction: a new technique with better long-term stability than four-strand. Presented at the 2006 meeting of the Arthroscopy Association of North America, Hollywood, FL, May, 2006. 3. Goradia VK, Grana WA. A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts. Arthroscopy 2001;17:383–392. 4. Howell SM, Deutsch ML. Comparison of endoscopic and two-incision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy 1999;15:594–606. 5. Hamada M, Shino K, Horibe S, et al. Preoperative anterior knee laxity did not influence postoperative stability restored by anterior cruciate ligament reconstruction. Arthroscopy 2000;16:477–482. 6. Maeda A, Shino K, Horibe S, et al. Anterior cruciate ligament reconstruction with multistranded autogenous semitendinosus tendon. Am J Sports Med 1996;24:504–509. 7. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 8. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 9. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 10. Gobbi A, Mahajan S, Zanazzo M, et al. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation in athletes. Arthroscopy 2003;19:592–601. 11. Gobbi A, Tuy B, Mahajan S, et al. Quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a clinical investigation in a group of athletes. Arthroscopy 2003;19:691–699. 12. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 13. Howell SM, Deutsch ML. Comparison of endoscopic and two-incision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy 1999;15:594–606. 14. Goradia VK, Grana WA. A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts. Arthroscopy 2001;17:383–392. 15. Zantop T, Brucker P, Bell K, et al. In The effect of tunnel-graft length on the primary and secondary stability in ACL reconstruction: a study in a goat model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 16. Yamazaki S, Yasuda K, Tomita F, et al. The effect of intraosseous graft length on tendon-bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 2006;14:1086–1093.

EZLoc Femoral Fixation of a Soft Tissue Graft ABSTRACT The EZLoc (Arthrotek, Warsaw, IN) is a cortical femoral fixation device for a soft tissue anterior cruciate ligament (ACL) reconstruction that combines superior fixation properties (high resistance to slippage, infinite stiffness, and 1427N strength) with a simple surgical technique. The EZLoc consists of a deployable lever arm connected to an axle in a slotted body through which the ACL graft is looped. The EZLoc comes sterilely package with a sharp-tip passing pin that is secured in the slotted body with a suture tied under tension. The passing pin is passed through the tunnels, the gold lever arm is positioned lateral, and the soft tissue graft is looped through the slot in the EZLoc. The graft is pulled into the femoral tunnel. When the lever arm clears the femoral tunnel, the suture is cut, the passing pin is removed, the suture is tensioned, and the lever arm is deployed, which fixes the EZLoc on cortical bone. The EZLoc can be used with both the one- and two-tunnel ACL reconstruction techniques, and it is available in three diameters and three lengths. The EZLoc femoral fixation resists slippage and is stiffer and stronger than other femoral fixation techniques currently in use with a soft tissue ACL graft. The EZLoc is an ideal fixation for the skeletally immature knee.

INTRODUCTION Fixation of the looped end of a soft tissue ACL graft to the femur poses different challenges than

fixation of the free ends to the tibia. Metal crosspin devices such as the Bone Mulch Screw and Transfix have set the standard for femoral fixation because of their superior slippage resistance, stiffness, and strength.1–4 Although these metal cross-pin devices work extremely well, their surgical techniques consists of multiple challenging steps and a lateral incision through the iliotibial band, which can damage the lateral collateral ligament.5 Prominent seating of the head of the cross-pin causes iliotibial band pain,6 and countersinking below the cortex complicates and may prevent hardware removal at the time of revision surgery (Fig. 33-1). The design of the EZLoc femoral fixation device (Arthrotek) replicates the superior fixation of the metal cross-pins while simplifying the surgical procedure. The use of the EZLoc does not require a lateral incision, and the lever arm seats on cortical bone so that it is neither prominent nor countersunk, which facilitates revision surgery. Both the high-volume and occasional ACL surgeon should find the EZLoc to be simpler, quicker, and easier to use than other femoral fixation techniques including the crosspins. Brace-free, aggressive rehabilitation is safe because the EZLoc provides superior slippage resistance, stiffness, and strength.

33 CHAPTER

Stephen M. Howell

Design, Diameter, Length, Packaging, and Mechanism of the EZLoc The EZLoc is a cortical fixation device that consists of a deployable lever arm connected to 233

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FIG. 33-1 Radiographs of a two-stage revision in which the cross-pin was buried beneath the cortical bone on the femur and could not be removed at the time of hardware removal and bone grafting of the originally misplaced femoral and tibial tunnels (denser bone). At the second stage, the tibial tunnel was placed at an angle of 60 to 65 degrees in the coronal plane, which moved the femoral tunnel farther down the sidewall, which prevented posterior cruciate ligament impingement, and more posterior in the sagittal plane, which prevented roof impingement. The EZLoc sits low in profile but is still easy to find at the time of revision surgery because the lever arm rest on cortical bone.

an axle in a slotted body through which the ACL graft is looped. The lever arm grips cortical bone on the anterolateral side of the femur, which provides superior slippage resistance, high stiffness, and strong cortical fixation. The lever arm provides rigid fixation that is better than that of a cross-pin because the lever arm seats on cortical bone on the anterolateral femur, which is 50 times stronger than cancellous bone7 (Fig. 33-2). The EZLoc is available in three diameters (5/6, 7/8, 9/10) and three lengths (short, standard, long). The diameter of the EZLoc is selected to match the diameter of the femoral and tibial tunnels. The 7/8 EZLoc is used with a 7- and 8-mm diameter tunnel, and the 9/10 EZLoc is used with a 9- and 10-mm diameter tunnel. The 5/6 EZLoc is used in the posterolateral tunnel with the two-tunnel technique, and the 7/8 EZLoc is used in the anteromedial tunnel. The EZLoc comes in different lengths, which control the length of the graft in the femoral tunnel and ensure that enough graft extends beyond the tibial tunnel for secure fixation. The most commonly used EZLoc length is the standard version. The standard version is used in a femoral tunnel from 35 to 50 mm in length, which provides 22 to 37 mm of soft tissue graft in the tunnel, promoting rapid, stiff, and strong tendon tunnel healing.8–10 The long version is used in a femoral tunnel that is longer than 50 mm, and the length of the 234

soft tissue graft in the femoral tunnel is computed by subtracting 22 mm from the length of the lateral wall of the femoral tunnel. The short version is used in a femoral tunnel that is shorter than 35 mm, and the length of the graft in

FIG. 33-2 The EZLoc is a cortical femoral fixation device consisting of a gold-colored lever arm (a) connected to a slotted body (b) by an axle (c). The lever arm provides slippage-resistant, stiff, and strong fixation similar to a cross-pin because it seats on cortical bone (circle). The lever arm prevents proximal and distal micromotion, and the body prevents anteroposterior and medial lateral micromotion. The slot in the body accepts both oneand two-strand soft tissue anterior cruciate ligament grafts.

EZLoc Femoral Fixation of a Soft Tissue Graft

FIG. 33-3 The EZLoc comes in a sterile package with a passing pin and suture. The dull end of a 16-inch-long, sharp-tip passing pin is secured in the proximal end of the slotted body by a suture tied under tension. The passing pin is used to orient the lever arm laterally and to pull the anterior cruciate ligament (ACL) graft into place. In the special situation when the EZLoc is used in the posterolateral femoral tunnel in a two-tunnel ACL reconstruction technique and the posterolateral femoral tunnel is not in the same axis as the tibial tunnel, the passing pin is removed from the EZLoc and the suture is used to pull the graft.

FIG. 33-4 Radiograph showing two EZLocs fixing the graft in the femur in the two-tunnel technique. A 5/6 short EZLoc fixes a single loop of gracilis tendon in the posterolateral femoral tunnel. A 7/8 standard EZLoc fixes a single loop of semitendinosus tendon in the more vertical anteromedial femoral tunnel.

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the tunnel is computed by subtracting 7 mm from the length of the lateral wall of the femoral tunnel. For ease of use, each EZLoc comes preassembled on a 16-inch-long, sharp-tip passing pin that is secured by a suture tied under tension and is sterile (Figs. 33-3 and 33-4). The suture has two functions: to keep the passing pin in the body of the EZLoc during passing of the graft and to deploy the lever arm once the lever arm clears the femoral tunnel. The suture passes through a hole in the lever arm and through two holes at the sharp end of the passing pin. The suture is tied under tension, which keeps the dull end of the passing pin inside the EZLoc and keeps the lever arm undeployed. The lever arm is positioned laterally, tension is applied to the pin, and the EZLoc and soft tissue graft are pulled across the knee. Once the ACL graft is pulled into the femoral tunnel, the suture is cut, the passing pin is removed, the suture is tensioned, and the lever arm deploys.

Fixation Properties of the EZLoc A successful ACL reconstruction with a soft tissue graft depends on the use of a femoral fixation device that has superior fixation properties and enhances biological healing of the tendon to the tunnel wall. The fixation properties of the femoral fixation device should provide high strength and high stiffness, be resistant to slippage, and allow circumferential healing of the tendon to the tunnel wall.4,9,11–13 Because a soft tissue graft takes longer to heal to the tunnel than a bone plug, the femoral fixation of a soft tissue graft should be more slippage resistant, stiffer, and stronger than the femoral fixation of a bone plug graft.14 The use of the EZLoc to fix a soft tissue graft in the femur is a sound choice because its fixation properties are second to none and the device allows circumferential healing. The strength of the EZLoc is 1427N, which is stronger than the closed-loop Endobutton (1086N) and the cross-pins (Bone Mulch Screw, 1112N; Transfix, 1303N; RigidFix, 868N).2,15 The stiffness of the lever arm of the EZLoc on cortical bone is infinitely high compared with the stiffness of the more elastic soft tissue graft. A benefit of using a high-stiffness femoral fixation device such as the EZLoc is that the tension applied to the graft to restore anterior laxity is lowered4,12,13,16 and the risk of developing anterior laxity during early motion is lessened.11 The slippage resistance of the EZLoc under cyclical loading has not been measured; however, the slippage with a metal lever arm on cortical bone should be at least as small as a cross-pin because the mechanism of looping the graft over a metal post is identical in both types of fixation methods.17 The EZLoc promotes healing of the tendon to the tunnel wall better than an interference screw because the soft tissue graft fixed with the EZLoc heals circumferentially to the tunnel wall.9 235

Anterior Cruciate Ligament Reconstruction The combination of the EZLoc with the WasherLoc and bone dowel tibial fixation device creates a graft-fixation device construct with superior fixation properties that allow an early, aggressive, and brace-free rehabilitation.18 With this fixation technique and correct tunnel placement, the majority of patients regain sufficient function and confidence in their knee to return to preinjury activity level 4 months after reconstruction, similar to femoral fixation with the Bone Mulch Screw.19

RELIABLE SURGICAL TECHNIQUE WITH MINIMAL STEPS Important considerations of a femoral fixation device are reliable insertion, consistent fixation performance, minimal surgical steps and instruments, and easy use for both the high-volume and occasional ACL surgeon and the experienced and inexperienced surgical team. The reliability of the EZLoc insertion depends on correct sizing of the soft tissue ACL graft, the type of femoral reamer, the width of the slotted body, and the broad surface of the lever arm. The ACL graft is correctly sized when the diameter of the tunnel matches the diameter of the smallest sleeve that can be “thrown” rather than pushed over the looped end of the graft. The use of a 1-inch femoral reamer creates a smoother tunnel than the acorn-tip reamer, preventing the EZLoc and graft from “hanging up” during passage across the knee. The wideness of the slotted body blocks the EZLoc from getting caught in the lateral thigh musculature. The broad surface of the lever arm easily catches the cortical edge of the femoral tunnel, providing a solid feel when the EZLoc is seated. The EZLoc provides consistent fixation in bone affected by a variety of conditions. Softening of the cancellous bone in the femur from injury, disuse, increased age, smoking, and alcohol use does not affect the fixation properties because the EZLoc is seated on cortical bone. A posterior wall blowout or a thin, 1-mm back wall to the femoral tunnel, which is required so that the tension in the graft matches that of the intact ACL,20 does not affect the fixation performance of the EZLoc in contrast to the interference screw, which requires excessive anterior placement of the femoral tunnel to provide fixation. The surgical steps and instruments for fixing a soft tissue ACL graft to the femur are simple and few. The diameter of the tibial and femoral tunnel is chosen from the smallest cylinder that freely passes over the ACL graft when it is looped through a sizing stick (described later). The length of the lateral wall of the femoral tunnel is measured with a depth gauge. The tip of the passing pin is inserted across the tibial and femoral tunnel and through the skin of the

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anterolateral thigh. The passing pin is rotated until the lever arm faces laterally. The soft tissue graft is passed through the slot in the EZLoc, and the length of the femoral tunnel is marked on the graft by measuring from the distal tip of the lever arm. The passing pin is pulled until the mark on the graft enters the femoral tunnel. The suture is cut, the passing pin is removed, the suture is tensioned, and the lever arm is deployed. The end of the graft exiting the tibial tunnel is tensioned, which seats the lever arm on the anterolateral cortex of the femur. Passing the graft and rigidly fixing the graft to the femur are accomplished confidently and reliably in essentially the same step. The high-volume and occasional ACL surgeon and the experienced and inexperienced surgical team can easily master the EZLoc femoral fixation technique.

Surgical Technique The surgical technique for fixing a soft tissue ACL graft to the femur with the EZLoc using a single-tunnel, transtibial technique can be viewed in streaming video online (http:// www.drstevehowell.com/ezloc_video.cfm) as well as in the DVD and website that accompany this textbook.

Prepare and Size the Hamstring or Tibialis Allograft Regardless of whether an autogenous hamstring graft or a tibialis allograft is used, the preparation of the tendons requires no special suturing or tensioning for use with the EZLoc. Sew a #1 suture to each end of each tendon. Use the 7- to 8-mm and 9- to 10-mm sizing sticks to determine the diameter of the graft. Loop the graft in the slot of the sizing stick. Pass sleeves of different diameters over the graft. Choose the diameter of the smallest sleeve that can be “thrown” rather than pushed over the looped end of the graft to drill the femoral and tibial tunnels. Store the graft inside the sizing sleeve in a saline basin to keep it moist and to prevent swelling until it is used (Fig. 33-5).

Place the Tibial Tunnel without Posterior Cruciate Ligament and Roof Impingement The EZLoc is most easily inserted with use of the transtibial technique, in which the femoral tunnel is drilled through the tibial tunnel (see Chapter 21). Correct placement of the tibial tunnel ensures correct placement of the femoral when the tibial tunnel is drilled with the Howell 65-degree tibial guide (Arthrotek). The 65-degree tibial guide places the ACL graft without posterior cruciate ligament (PCL) and roof impingement. A wallplasty is performed until the width between the lateral femoral condyle and PCL exceeds the width of the graft by

EZLoc Femoral Fixation of a Soft Tissue Graft

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leaves ridges that can block the passage of the EZLoc. Use a cannulated 1-inch femoral reamer (Arthrotek) that matches the diameter of the ACL graft, and drill the femoral tunnel through the anterolateral cortex of the femur. Draw the reamer in and out along the entire length of the femoral tunnel, including the cortex, two to three times to smooth the tunnel (Fig. 33-6). The EZLoc does not hang up when the femoral tunnel is drilled with the 1-inch femoral reamer.

FIG. 33-5 The double-looped semitendinosus and gracilis autograft and the tibialis allograft require no special suturing for use with the EZLoc. The graft should be submerged in a saline basin and stored inside a sizing sleeve to keep it moist and to prevent swelling until it is used.

1 mm. The tibial tunnel is angled 60 to 65 degrees with the medial joint line, which positions the lateral edge of the tibial tunnel such that it passes through the apex of the lateral tibial spine in the coronal plane to avoid PCL impingement. Because the tibial tunnel is drilled with the knee in full extension and the guide references off the intercondylar roof, the center of the tibial tunnel is placed 5 to 6 mm posterior and parallel to the intercondylar roof with the knee in maximum hyperextension in the sagittal plane, which avoids roof impingement without performing a roofplasty.20–24

Place and Adjust the Length of the Femoral Tunnel

Measure the Femoral Tunnel and Choose the Length of the EZLoc Insert the depth gauge through the tibial tunnel into the femoral tunnel. Hook a tip of the depth gauge on the lateral cortex of the femur. Read the length of the lateral wall of the femoral tunnel at the point where the depth gauge enters the femoral tunnel (Fig. 33-7). Choose a standard EZLoc when the femoral tunnel length is between 35 and 50 mm, a short EZLoc when the femoral tunnel length is less than 35 mm, and a long EZLoc when the femoral tunnel length is greater than 50 mm.

Fix the Soft Tissue Graft to the Femur The first step in fixing the soft tissue ACL graft to the femur is to insert the passing pin attached to the EZLoc through the tibial tunnel, intercondylar notch, femoral tunnel, and skin overlying the anterolateral thigh. Rotate the passing pin until the gold lever arm faces laterally. Loop the soft tissue ACL

Place the femoral tunnel with a 1-mm back wall using a sizespecific femoral aimer (Arthrotek) that matches the diameter of the graft. Insert the femoral aimer through the tibial tunnel, and hook it over the posterior edge of the intercondylar notch. Select the 2.4-mm drill tip guidewire with marks at 35 and 50 mm (Arthrotek). Make a pilot hole in the femur by drilling the guidewire through the femoral aimer. Remove the guidewire and femoral aimer, and flex the knee to 90 degrees. Reinsert the guidewire through the tibial tunnel and into the pilot hole on the femur. Drill the guidewire until the tip of the guidewire stops at the anterolateral cortex of the femur, and then check the marks. If the 35-mm mark is inside the femur but the 50-mm mark is not, then the length of the femoral tunnel will be between 35 and 50 mm and a standard EZLoc will be used. If the 50-mm mark is inside the femur, then the length of the femoral tunnel will be greater than 50 mm and a long EZLoc will be used. The surgeon can adjust the length of the femoral tunnel by redrilling the guidewire with the knee in different degrees of flexion.

Drill the Femoral Tunnel with a 1-Inch Femoral Reamer The use of a 1-inch femoral reamer is recommended rather than an acorn-tip reamer because the acorn-tip reamer

FIG. 33-6 The femoral tunnel should be drilled with a 1-inch reamer rather than an acorn reamer. The 1-inch reamer creates a smooth femoral tunnel, whereas the acorn reamer leaves ridges. The EZLoc passes more reliably in a smooth femoral tunnel.

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Anterior Cruciate Ligament Reconstruction

FIG. 33-7 The length of the lateral wall of the femoral tunnel is measured with a depth gauge inserted through the tibial and femoral tunnels. The tip of the depth gauge is hooked on the lateral cortex of the femur. The length of femoral tunnel in this subject is 45 mm and is measured at the opening of the femoral tunnel into the notch.

graft through the slot in the body of the EZLoc, and tie together the sutures at the end of each tendon. Mark the length of the femoral tunnel on the graft by measuring from the tip of the lever arm (Fig. 33-8). Pull the passing pin proximally until the lever arm enters the notch, and confirm that the lever arm is still facing laterally. Pull the passing pin until the mark of the graft enters the femoral tunnel. Cut the suture, remove the passing pin, and tension the suture, which deploys the lever arm. Pull on the distal end of the graft until the sudden, firm grip of the lever arm on cortical bone is felt. The lever arm rests laterally and in low profile on the anterolateral cortex of the femur (see Fig. 33-1).

Tibial Fixation Fix the graft to the tibia with the knee in maximal extension. We prefer to use the WasherLoc with compaction of a bone dowel, which is described in detail in Chapter 29 in this textbook.

EZLOC AND THE SKELETALLY IMMATURE PATIENT ACL reconstruction with a soft tissue graft is considered the treatment of choice in the skeletally immature patient to prevent uncorrectable injury to the menisci and articular 238

FIG. 33-8 The gold lever arm on the EZLoc faces laterally (arrow). The soft tissue graft is looped through the slot in the body of the EZLoc. A ruler is placed at the distal tip of the gold lever arm, and the length of the femoral tunnel is marked on the graft (blue line). The graft is pulled across the knee until the mark enters the femoral tunnel.

cartilage.25 The EZLoc is designed to function without causing a growth plate arrest in the skeletally immature patient in contrast to the interference screw and cross-pin (Fig. 33-9). The EZLoc grips the femoral cortex several centimeters proximal to the growth plate. The body of the EZLoc is centered in the femoral tunnel and does not purchase bone on either side of the growth plate; therefore interference with growth is unlikely. In contrast to the EZLoc, the placement of an interference screw across the growth plate seems unwise, and oblique placement of the cross-pin has caused valgus angulation.26

EZLOC AND DRILLING THROUGH THE FEMORAL CORTEX Drilling a 7- to 10-mm diameter tunnel through the lateral femoral cortex to pass the EZLoc produces a temporary stress riser that has not been reported to cause a femur fracture. Drilling through the lateral femoral cortex with a soft tissue graft and looping the graft around a fixation post outside the tunnel was the standard femoral fixation technique from the

EZLoc Femoral Fixation of a Soft Tissue Graft

33

FIG. 33-9 The EZLoc can be used with concern of a growth plate (arrow) arrest in the skeletally immature patient because it does not cross the growth plate. The anteroposterior and lateral radiographs (upper left and right images, respectively) and MRI (lower images) show the EZLoc several centimeters proximal to the growth plate (arrows).

1970s to early 1990s.27,28 During that time period, there were no published reports of femoral fracture around the drill hole. One reason that drilling the femoral tunnel across the femur did not cause a reportable femoral fracture is that the bone remodels along the length of the tunnel. Remodeling is especially rapid with the EZLoc because the titanium body encourages bone ingrowth that obliterates the tunnel within 4 to 6 months (Fig. 33-10).

REVISION SURGERY WITH THE EZLOC Because of the rapid growth of bone around the EZLoc, revision surgery may seem to be a challenge. Surprisingly,

removal of the EZLoc is straightforward because the lever arm sits on the cortical bone and is easily located through a small anterolateral incision (Fig. 33-11). First, the distal end of the EZLoc should be freed by removing the remnant of the soft tissue ACL graft from the femoral tunnel with either a reamer on slow speed or a tissue ablation device. Next, a small curved gouge is used around the periphery of the proximal end to separate the ingrowth of cortical bone from the EZLoc. A small towel clip is used to grab the lever arm, and the EZLoc is pulled free of the tunnel. If the femoral tunnel was positioned correctly, and because we believe there is no tunnel widening with the EZLoc, the same tunnel and a new EZLoc can then be used to place and fix the revision ACL graft. 239

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FIG. 33-10 Drilling the femoral tunnel through the anterolateral cortex does not produce a clinically relevant stress riser. Bone grows rapidly around the EZLoc (arrows) because the device is made of titanium. The rapid ingrowth and lack of tunnel widening is a testament to the rigid fixation provided by the EZLoc.

TROUBLESHOOTING THE EZLOC Difficulty in passing the EZLoc up the femoral tunnel can result in premature deployment of the EZLoc inside the femoral tunnel, but this can be prevented. Prevention is based on sensing that the EZLoc and graft slide easily up the tibial tunnel but are tighter in the femoral tunnel, which is best detected by the surgeon and not an assistant pulling the EZLoc into the femoral tunnel. If the surgeon senses

that the EZLoc is too tight in the femoral tunnel, then the graft and passing pin should be removed and the diameter of the femoral reamer should be checked. If the diameter of the reamer was too small, then redrill with the correct 1-inch reamer. If the reamer diameter was correct but an acorn-tip reamer was used, then redrill with a reamer 1 mm larger in size. If the reamer was correct and a 1-inch reamer was used, then redrill the femoral tunnel, pistoning the reamer up and down the tunnel and through the lateral cortex several times to be sure that all ridges are removed. Pistoning the 1-inch reamer to remove ridges should be routinely done in young subjects because the hard bone causes small deviations in the path of the reamer. If the EZLoc does prematurely deploy, then check the location of the deployment inside the femoral tunnel intraoperatively with a radiograph. If the deployment occurs at the proximal end of the femoral tunnel and the lever arm is in the cancellous bone, then the EZLoc can be left in place because it has not been shown to move. If the deployment occurs at the distal end of the femoral tunnel, then use a blunt scope trocar to push the EZLoc and graft up the femoral tunnel and out through the cortex. As in any complication, the best way to get out of it is to never get into it—prevention is the key.

CONCLUSION The EZLoc is a femoral fixation device for soft tissue ACL reconstruction that is simple and reliable for both the highvolume and occasional ACL surgeon and surgical team. The

FIG. 33-11 Removal of the EZLoc is straightforward because the lever arm, which seats on the cortex of the anterolateral femur, is easily palpated through a small skin incision (left). The cortical bone that has grown in and around the proximal end of the EZLoc is freed with a small curved gouge. A small towel clip is used to grab the lever arm, and the EZLoc is removed (center).27,28 Dense bone has grown into the titanium EZLoc (right).

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EZLoc Femoral Fixation of a Soft Tissue Graft EZLoc combines superior fixation properties (1427N strength, 8 N/mm stiffness, and high resistance to slippage) and allows circumferential healing of the tendon graft to the tunnel wall, which allows aggressive rehabilitation without a brace and return to sport at 4 months.19,27,29 The EZLoc works well in patients with hard and soft bone and in the skeletally immature knee. Revision is straightforward, although a small anterolateral incision is required to identify and remove the EZLoc.

References 1. Brown CH, Jr, Wilson DR, Hecker AT, et al. Graft-bone motion and tensile properties of hamstring and patellar tendon anterior cruciate ligament femoral graft fixation under cyclic loading. Arthroscopy 2004;20:922–935. 2. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 3. Kudo T, Tohyama H, Minami A, et al. The effect of cyclic loading on the biomechanical characteristics of the femur-graft-tibia complex after anterior cruciate ligament reconstruction using Bone Mulch screw/ WasherLoc fixation. Clin Biomech (Bristol, Avon) 2005;20:414–420. 4. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 5. Pujol N, David T, Bauer T, et al. Transverse femoral fixation in anterior cruciate ligament (ACL) reconstruction with hamstrings grafts: an anatomic study about the relationships between the transcondylar device and the posterolateral structures of the knee. Knee Surg Sports Traumatol Arthrosc 2006;14:724–729. 6. Pelfort X, Monllau JC, Puig L, et al. Iliotibial band friction syndrome after anterior cruciate ligament reconstruction using the transfix device: report of two cases and review of the literature. Knee Surg Sports Traumatol Arthrosc 2006;14:586–589. 7. Amis AA. The strength of artificial ligament anchorages. A comparative experimental study. J Bone Joint Surg 1988;70B:397–403. 8. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 9. Singhatat W, Lawhorn KW, Howell SM, et al. How four weeks of implantation affect the strength and stiffness of a tendon graft in a bone tunnel: a study of two fixation devices in an extraarticular model in ovine. Am J Sports Med 2002;30:506–513. 10. Zacharias I, Howell SM, Hull ML, et al. In vivo calibration of a femoral fixation device transducer for measuring anterior cruciate ligament graft tension: a study in an ovine model. J Biomech Eng 2001;123:355–361. 11. Grover DM, Howell SM, Hull ML. Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices. J Bone Joint Surg 2005;87A:381–390. 12. Karchin A, Hull ML, Howell SM. Initial tension and anterior loaddisplacement behavior of high-stiffness anterior cruciate ligament graft constructs. J Bone Joint Surg 2004;86A:1675–1683.

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13. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 14. Tomita F, Yasuda K, Mikami S, et al. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bonepatellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy 2001;17:461–476. 15. Becker R, Voigt D, Starke C, et al. Biomechanical properties of quadruple tendon and patellar tendon femoral fixation techniques. Knee Surg Sports Traumatol Arthrosc 2001;9:337–342. 16. Eagar P, Hull ML, Howell SM. How the fixation method stiffness and initial tension affect anterior load-displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft. J Orthop Res 2004;22:613–624. 17. Roos PJ, Hull ML, Howell SM. Lengthening of double-looped tendon graft constructs in three regions after cyclic loading: a study using Roentgen stereophotogrammetric analysis. J Orthop Res 2004;22:839–846. 18. Matsumoto A, Howell SM. WasherLoc and bone dowel: a rigid slippageresistant tibial fixation device for a soft tissue anterior cruciate ligament graft. Tech Orthop 2005;20:278–282. 19. Howell SM, Deutsch ML. Comparison of endoscopic and twoincision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy 1999;15:594–606. 20. Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg 2003;85A:1018–1029. 21. Cuomo P, Edwards A, Giron F, et al. Validation of the 65 degrees Howell guide for anterior cruciate ligament reconstruction. Arthroscopy 2006;22:70–75. 22. Howell SM, Barad SJ. Knee extension and its relationship to the slope of the intercondylar roof. Implications for positioning the tibial tunnel in anterior cruciate ligament reconstructions. Am J Sports Med 1995;23:288–294. 23. Howell SM, Clark JA, Farley TE. A rationale for predicting anterior cruciate graft impingement by the intercondylar roof. A magnetic resonance imaging study. Am J Sports Med 1991;19:276–282. 24. Howell SM, Lawhorn KW. Gravity reduces the tibia when using a tibial guide that targets the intercondylar roof. Am J Sports Med 2004;32:1702–1710. 25. Aichroth PM, Patel DV, Zorrilla P. The natural history and treatment of rupture of the anterior cruciate ligament in children and adolescents. A prospective review. J Bone Joint Surg 2002;84B:38–41. 26. Koman JD, Sanders JO. Valgus deformity after reconstruction of the anterior cruciate ligament in a skeletally immature patient. A case report. J Bone Joint Surg 1999;81:711–715. 27. Howell SM, Taylor MA. Brace-free rehabilitation, with early return to activity, for knees reconstructed with a double-looped semitendinosus and gracilis graft. J Bone Joint Surg 1996;78A:814–825. 28. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg Am 1993;75A:1044–1055. 29. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. A prospective, randomized clinical trial. J Bone Joint Surg 2004;86A:2143–2155.

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34 CHAPTER

Paul Re Tony Wanich Russell F. Warren

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SUB PART II CROSS-PIN

Stratis ST Femoral Fixation System INTRODUCTION It has been estimated that approximately 200,000 anterior cruciate ligament (ACL) injuries occur annually, with approximately 100,000 patients per year undergoing reconstruction.1 Over the past decade, ACL reconstruction utilizing soft tissue grafts, such as hamstring autograft or tibialis anterior allograft, has gained increased popularity compared with bone– patellar tendon–bone (BPTB) autograft due to the decreased morbidity of hamstring harvesting, excellent clinical results, and availability of a variety of soft tissue allograft constructs. There remains continued controversy regarding graft options for ACL reconstructions. Of the graft choices available, the two most commonly used are autologous BPTB grafts and autologous hamstring tendon grafts. Even more perplexing is the number of fixation methods currently available. For many surgeons, BPTB autograft remains the gold standard. Several long-term studies have demonstrated good outcomes with the use of this graft.2,3 Due to the morbidity associated with BPTB autograft, the use of hamstring tendon autograft has become increasingly popular. A number of prospective clinical trials comparing patellar tendon versus hamstring tendon have demonstrated comparable clinical results after 2-year follow-up.4–9 Additional studies, including a study by Feller and Webster,10 have demonstrated increased laxity based on KT1000 in ACL reconstructions with hamstring

tendon compared with patellar tendon. However, this difference was not clinically significant because patients in both groups demonstrated similar clinical scores and functional outcomes. One of the primary advantages of using hamstring tendon in ACL reconstruction appears to be less donor site morbidity compared with patellar tendon. Namely, there is a lower incidence of anterior knee pain and a decreased risk of extension deficits, although some authors have found flexion deficits in patients with ACL reconstruction using hamstring tendon grafts.11,12 The weakness in extension or flexion following either patellar tendon or hamstring tendon harvest appears to be most pronounced early on, with differences diminishing between groups over time.13 Another concern regarding the use of hamstring tendon grafts is the phenomenon of tunnel widening associated with early forms of femoral fixation.14 With improvements in surgical technique and advances in femoral fixation devices, the differences in tunnel widening between hamstring and patellar tendon grafts have been reduced.15 The earliest forms of fixation for soft tissue grafts included post and washer and staple fixation. This required a significant lateral femoral dissection for the over-the-top or outside-in femoral guide, as well as placement of the devices used. Although the fixation strength was acceptable, the issues surrounding this technique included the surgical dissection and the rehabilitation consequences and the occurrence of painful hardware necessitating a

Stratis ST Femoral Fixation System second procedure for hardware removal and the so-called “bungee and windshield wiper effect.” Although biomechanical studies have shown that hamstring autografts have an ultimate yield strength greater than the native ACL and a stiffness curve more similar to the native ACL, the distally fixed construct placed these grafts at a disadvantage.16,17 The femoral fixation is more than 50 to 70 mm from the intraarticular origin of the femoral tunnel, which essentially triples the length of the working graft when compared with the native ACL, whose average intraarticular length is about 25 mm. This results in tripling the creep and decreasing the stiffness, making the construct feel more elastic. Because creep is dependent on the overall length of the graft, shortening the functional length of the graft will result in less stretch to the graft at follow-up. The distal fixation also acts as a pivot point about which the graft moves during knee flexion and extension until the graft–femoral tunnel interface matures. This results in a cone-shaped tunnel widening at the articular femoral origin. Although the effect of tunnel widening on clinical outcome remains unclear, there is concern that this may affect healing of the graft–femoral tunnel interface and also create problems in the revision setting.18,19 To address these issues, different fixation devices have been devised and used. Suspensory anterior-lateral femoral cortical fixation devices have had great clinical success. They eliminate the need for a secondary lateral dissection and have good pullout strength.20 They do, however, suffer the consequences of elongation resulting from excessive length of the functional graft due to the distance of femoral cortical fixation. The use of interference screws has addressed the issue of aperture fixation at the femur. However, the concern regarding the damage the screw threads cause to the graft, as well as the less-than-optimal pullout strength, has limited their use. In addition, interference screws take up most of the space within the femoral tunnel, pushing the soft tissue graft to one side and limiting its contact with the femoral tunnel, which raises concerns of impaired graft tunnel healing. Recently, transverse femoral tunnel pinning (transfemoral) fixation has been introduced and is gaining in popularity. These devices either spear the graft or drape the graft over a fixation pin in an anteroposterior orientation. The different designs have resulted in improved fixation and pullout strength.21,22 However, for each design there are concerns regarding graft damage and passage of the graft into the tunnel by pulling either axially or perpendicular to the tunnel, which often necessitates making a wider femoral tunnel to aid in graft passage. Any construct that spears the graft compromises its integrity and secondarily subjects it to increased creep. This

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increased creep is due to the fact that the collagen fibers in the graft run longitudinally in bundles with limited cross-fiber bundle strength. If these bundles are speared and pulled, the graft essentially tears along these fiber bundle lines. Other transfemoral fixation devices require that a flexible wire be drilled across the femoral tunnel and out the other side; the wire is then retrieved down the tunnel, across the joint, and out the tibial tunnel. Here the graft is draped across the wire and pulled back up into the tunnel by pulling on the limbs of the wire exiting medially and laterally. Once pulled back up, the fixation pin or device is then passed. Axially pulling any graft is mechanically harder than pushing a graft into the femoral tunnel. These transfemoral fixation devices are even more mechanically disadvantaged because the force vector to pull the graft up into the tunnel is perpendicular to the axis through which the graft is passed. This weaker pull makes it difficult to pass the graft, often requiring surgeons to oversize the tunnel to ease passage. This oversizing results in less graft compression within the tunnel, which could ultimately impair healing. Anatomical studies show that the femoral footprint of the ACL is oriented in anteromedial (AM) and posterolateral (PL) bundles. These transfemoral tunnel devices orient the bundles in an anterior and posterior position rather than the correct anatomical orientation.

DESIGN RATIONALE OF THE STRATIS ST With the knowledge gained by devices and techniques that preceded it, the Stratis ST (Scandius Biomedical, Littleton, MA) was designed to address the major points and goals that define the ultimate soft tissue fixation device. Any clinically successful device needs to (1) not compromise graft integrity, (2) have excellent pullout strength, (3) have aperture fixation with graft tunnel compression and optimized graft tunnel contact, (4) be pushed into the femoral tunnel, and (5) orient graft limbs in the correct anatomical orientation. These qualities are discussed in detail in this section. The Stratis ST femoral fixation system consists of a graft block and a ribbed transverse locking pin (Fig. 34-1). The graft block and pin are available in nonabsorbable polymer and absorbable poly-L-lactic-acid (PLLA). The graft block is available in 25-mm and 35-mm lengths and diameters of 8, 9, and 10 mm. The graft block has a suture eyelet most proximally, followed by a locking portal that receives the transverse pin, followed next by the graft portal, which receives the soft tissue graft. The graft block tapers distally into a 2-mm biconcave fin, which receives the draped soft tissue graft and provides graft tunnel compression and distal aperture fixation. At the distal tip of the graft block is the docking station for the insertion tool. 243

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FIG. 34-2 Stratis ST femoral fixation system with soft tissue graft. FIG. 34-1 Stratis ST femoral fixation graft block and transverse locking pin.

The transverse locking pin is 40 mm long, of which 28 mm is smooth and 4 mm in diameter, with the remaining 12 mm being ribbed and 6 mm in diameter. The ribbed portion stops the pin from moving too far medially through the graft block and also locks it into the lateral femoral condyle, stopping the pin from backing out. The transverse pin was designed with the locking portion being ribbed instead of screw threaded because mechanical studies show that screw-threaded devices are more prone to back out under cyclical loading than are ribbed devices.

1. Do Not Compromise Graft Integrity The Stratis ST femoral fixation system is designed for use with any soft tissue graft, with the quadrupled hamstring tendon being the most common autograft and tibialis anterior being the most common allograft used. The graft is passed through the distal graft portal and draped distally (Fig. 34-2). This hole is tapered smooth and contoured to deliver the graft to the distal biconcave compression fins. The transverse locking pin does not compromise or contact the soft tissue graft in any way. Instead, it locks the graft block within the femoral tunnel by docking with and traversing the more proximal locking portal. This ensures graft integrity and allows for a stiffer construct.

2. Have Excellent Pullout Strength With the locking pin engaged in the graft block, it forms a “fixed T” construct that yields superior biomechanical 244

characteristics. Pullout studies have shown an ultimate failure load of up to 1250N depending on which graft block is used. Cyclical loading studies of 50N to 250N showed no evidence of any creep, failure, or pin backout after 250,000 cycles.23 The locked fixed T construct also gives a theoretical decreased rotation moment because it is harder to rotate a fixed T construct through bone than it would be a simple transverse pin.

3. Have Aperture Fixation with Graft Tunnel Compression and Optimized Graft Tunnel Contact The graft block is seated no less than 5 mm from the femoral tunnel origin. This placement allows the fin of the graft block to provide rigid fixation at the tunnel aperture. In addition, the 2-mm-thick fin provides graft compression to the tunnel wall with more than 90% graft tunnel interface23 (Fig. 34-3).

4. Be Pushed into the Femoral Tunnel It is mechanically easier to push a graft into a tunnel than it is to pull the same-sized graft through the same-sized tunnel. Devices that rely on axially (or worse, perpendicularly) pulling the graft into the femoral tunnel are at a mechanical disadvantage. This disadvantage often requires oversizing the femoral tunnel to ease graft passage, which secondarily decreases graft tunnel compression and can interfere with graft tunnel healing.

Stratis ST Femoral Fixation System

34

limits fluid extravasation from the knee into the muscular compartment, further limiting damage to the quadriceps.

5. Orient the Graft Limbs in the Correct Anatomical Orientation

FIG. 34-3 Implanted view of Stratis ST femoral fixation system.

At the distal tip of the Stratis ST graft block is a docking station at which the insertion tool locks into place (Fig. 34-4). Once connected, the soft tissue graft–graft block construct can be delivered into the femoral tunnel. This locked construct allows the surgeon to better aim and guide the graft construct into the tunnel and then, once it is engaged with the tunnel, to push it into position with a mechanical advantage. This allows the surgeon to take full advantage of the compression fin and, if desired, oversize the graft but not the tunnel. Another advantage of not having to pull the graft into the femoral tunnel is that the guidewire does not have to breach the femoral cortex, nor does it have to traverse the quadriceps muscle and the skin. Therefore the wire and (secondarily) the graft-pulling suture are not there to damage the quadriceps. In addition, because there is no hole in the femoral cortex, no direct conduit exists from the intraarticular space and the anterior muscular compartment. This

FIG. 34-4 Stratis ST femoral fixation system insertion tool.

Anatomical studies show that the femoral ACL footprint consists of an anteromedial (AM) and a posterolateral (PM) bundle orientation. The design of the graft portal, which is parallel to the transverse pin, and the technique of insertion position the graft bundles into the correct anatomical orientation. This orientation, although probably not truly important to single-bundle reconstruction, plays an important role in anatomical single femoral tunnel, double-tibial tunnel, hybrid ACL reconstruction.24

TECHNIQUE Tendon Harvest Soft tissue autografts and allografts can be used with the Stratis ST system. We most commonly use the Stratis ST system for fixation of hamstring autografts. The technique we use for harvesting hamstring tendons is outlined in a paper by Solman and Pagnani.25 Briefly, make a longitudinal or oblique incision approximately 2 cm medial to the tibial tubercle and 4 cm distal to the joint line (Fig. 34-5). Dissect the subcutaneous tissue to expose the sartorius fascia. Incise the rolled edge of the sartorius fascia to expose the gracilis and semitendinosus tendons, which are covered by the sartorius (Fig. 34-6). Separately isolate each tendon with a 90-degree snap and deliver each under the sartorius (Fig. 34-7). Take care to cut all projecting bands and adhesions from each tendon, and bluntly dissect to the adductor hiatus. Sharply release the

FIG. 34-5 Incision for hamstring harvest.

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FIG. 34-6 Hamstring tendon.

FIG. 34-8 Prepared hamstring autograft.

Arthroscopic Preparation Pull the graft bundle through a graft-sizing block to determine the diameter. The diameter selected should be one through which the graft bundle fits tightly but still passes. Débride the ACL stump as necessary, and perform a lateral femoral notchplasty to visualize the over-the-top position as per the standard technique.

Creation of Tibial and Femoral Tunnels

FIG. 34-7 Isolation of gracilis and semitendinosus tendons.

tendons from their attachment to the tibia. Whipstitch the ends with a sturdy suture (usually #2 nonabsorbable). With the knee bent roughly 40 degrees, place the tendon. Manually palpate around the tendon to confirm that the facial bands have been released. Using a blunt tendon stripper, release the muscular attachment. Firmly pass the tendon stripper through the adductor hiatus and aim it toward the ischial tuberosity. Deliver the released tendon, and safely place it on the preparation table.

Graft Preparation Pinch the harvested tendon between the ends of a forceps and subsequently pull it through repeatedly in order to remove any remaining muscle. Alternatively, use a Cobb elevator or the back end of a ruler. Whipstitch the ends with a sturdy suture (usually #5 nonabsorbable). Fold the two grafts over a #5 suture (Fig. 34-8). 246

When using a transtibial approach, care should be taken because the position of the tibial tunnel influences the position of the femoral tunnel. The standard starting position of the tibial tunnel is just in front of the medial collateral ligament (MCL) and 1 cm proximal to the superior aspect of the sartorius fascia. This will create an appropriately angled tibial tunnel, which should be 30 degrees to the sagittal axis of the tibia. If the starting point is too lateral, then the graft position may be too vertical. If the starting point is too medial, then the ability to get far back in the femoral notch is compromised. The intraarticular entry point of the tibial tunnel is located in the posterior medial aspect of the ACL footprint. It is important not to be too anterior to avoid graft impingement. Using a tibial drill guide, advance a 2.25-mm, drilltipped guidewire into the intraarticular space. After appropriate guidewire position is confirmed, overdrill it with the appropriately sized cannulated drill bit. Clear the tunnel of bone debris, and chamfer it as necessary. With the knee typically bent to 90 degrees, position an appropriately sized over-the-top guide. With the appropriate position confirmed, drill the graduated guidewire until it engages the femoral cortex. Note the measured depth (Fig. 34-9). Typically a 25-mm-long graft block implant is used. However, a 35-mm graft block may be used

Stratis ST Femoral Fixation System

FIG. 34-9 Measure depth of femoral tunnel.

FIG. 34-11 Assembled tunnel guide/transverse guide.

if the guidewire hits the cortex at a depth of 50 mm or more. Advance the appropriate-diameter acorn drill over a guidewire and into the femur to a depth equal to the graft block to be used plus 5 mm; typically this will be 30 mm deep (Fig. 34-10).

Insert the drill sleeve and obturator into the opening on the distal end of the transverse guide. Make a 1-cm incision at the point where it engages skin. Using a snap to spread the iliotibial band, dissect down to the lateral femoral cortex. Advance the drill sleeve and obturator to the lateral femoral cortex (Fig. 34-12, A and B). Take care to ensure that no tissue is trapped between the sleeve and the cortex. When advancing the drill sleeve, hold the tunnel guide handle (rather than the transverse guide) and apply steady, light force to the drill sleeve; avoid applying excessive torque to the system. Use the locking nut to secure the drill sleeve to the transverse guide. Markings on the proximal aspect of the drill sleeve indicate the distance from the lateral cortex to the lateral wall of the femoral tunnel (see Fig. 34-12, A). To provide adequate purchase for the barbed end of the fixation pin, confirm that a minimum of 15 mm lateral distance is available. Remove the obturator from the drill sleeve. Advance the transverse drill through the drill sleeve and into the femur to the same depth as noted on the sleeve to create the transverse tunnel (Fig. 34-13). Run a sterile medical marking pen along the transverse guide to mark the skin on the lateral side of the knee, showing the orientation of the system. Remove the transverse drill, and insert the switching stick through the sleeve and into the tunnel. Take care to orient the switching stick in the same axis as the sleeve. Do not force the switching stick; it should slide through the sleeve and tunnel easily. Remove the transverse drill sleeve. Withdraw the tunnel guide; the slot in the distal end of the transverse guide will allow the switching stick to remain in the transverse tunnel. Note that if the switching stick is inserted too far at first, it will engage the tunnel guide and lock it in place, not allowing it to be removed.

Creation of Transverse Tunnel Select the tunnel guide that corresponds to the diameter of the femoral tunnel. Attach the transverse drill guide to the tunnel guide. Insert the assembled tunnel guide/transverse guide through the tibial tunnel until it is fully seated in the femoral tunnel (Fig. 34-11). The gradations on the tunnel guide should indicate a depth that corresponds to the drilled femoral tunnel depth. Orient the system so that the transverse guide is roughly 10 degrees posterior to the epicondylar axis. Alternatively, position the guide so that it is roughly parallel to the patellar plane.

FIG. 34-10 Create femoral tunnel.

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Anterior Cruciate Ligament Reconstruction

FIG. 34-12 A and B, Assembled tunnel guide/transverse guide with drill sleeve in place.

FIG. 34-13 Insert drill to create transverse tunnel.

FIG. 34-14 Prepared graft placed through lower eyelet of graft block.

Preparation of the Graft Block–Graft Construct

Additionally, the graft may be marked with a sterile marking pen prior to insertion to facilitate confirmation of insertion depth. Passage of the graft block–graft construct into the tibial and femoral tunnels may be facilitated by first conditioning the construct with the Stratis graft sizing/conditioning block. This will condition the construct diameter to within 0.2 mm of the tunnel diameter, easing passage while still proving tissue compression in the tunnel.

Choose the appropriate Stratis implant set. The set will contain a graft block and a fixation pin. Insert the prepared soft tissue graft into the lower eyelet of the graft block (Fig. 34-14). Place the graft block/graft construct onto the appropriate graft block inserter. Attach the transverse guide onto the graft block inserter (Fig. 34-15, A and B). Wrap the graft suture ends around the lock nut. Temporarily insert the drill sleeve into the distal end of the transverse guide, confirming that it lines up with the upper eyelet in the graft block and that the correct inserter has been selected. Remove the drill sleeve after confirming. 248

Insertion of the Graft Block Proper orientation is necessary to ensure that the fixation pin will align with the transverse tunnel. Use of the transverse guide and markings on the lateral side of the knee can facilitate proper orientation.

Stratis ST Femoral Fixation System

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FIG. 34-16 Switching stick through distal end of graft block.

FIG. 34-17 Drill sleeve advanced over switching stick. FIG. 34-15 A, Graft block–graft construct attached to graft inserter with transverse guide. B, Graft block–graft construct attached to graft inserter with transverse guide.

Advance the inserter–graft block construct through the tibial tunnel and fully into the femoral tunnel. Note that you may have to back out the switching stick to allow the graft block to fully seat. During this step, the switching stick should pass through the slot in the distal end of the transverse guide (Fig. 34-16). With the inserter/construct in position, advance the drill sleeve over the switching stick and to the cortex; secure it in place (Fig. 34-17). Make note of the depth measurements on the drill sleeve; these should be roughly the same as the previous measurements. To verify engagement, fully insert the switching stick; the stepped end should engage with the implant. After this is done, traction applied to the distal end of the graft will verify that the switching stick is engaged with the implant.

During this step, take care to maintain orientation of the switching stick along the axis of the transverse tunnel and to limit knee movements. This assists in maintaining correct tunnel alignment and helps preserve tunnel quality (off-axis insertion forces can compromise the tunnel, particularly in patients with poor bone quality).

Femoral Fixation Place the fixation pin on the fixation pin inserter (Fig. 34-18). Remove the switching stick. Advance the fixation pin inserter/fixation pin through the drill axis in the same fashion as the switching stick. Do not apply force; insertion through the sleeve and tunnel should encounter minimal resistance. Applying excessive off-axis force could damage the fixation pin. Confirm the depth by reading the measurements on the shaft of the fixation pin inserter (Fig. 34-19). These 249

Anterior Cruciate Ligament Reconstruction

FIG. 34-18 Fixation pin loaded onto inserter.

should be roughly the same as those drilled with the transverse drill and measured on the drill sleeve. The fixation pin will engage the upper eyelet of the graft block, providing device-to-device fixation and preserving graft integrity (Fig. 34-20). The graft block offers enhanced tissue-to-tunnel compression in a more anatomical mediolateral orientation. This compression provides rigid fixation at the joint line of the femur. Remove the fixation pin inserter by applying gentle lateral traction. Remove the drill sleeve. Apply traction to the graft to confirm rigid fixation. Remove the transverse guide nut, and unloop the sutures. Rock the graft block inserter anterior to posterior while pulling distally to dislodge the graft block and remove the inserter/transverse guide assembly. Using the tip of a finger, palpate the lateral transverse tunnel hole opening to confirm that the fixation pin is well seated.

FIG. 34-20 Close-up view of implant graft block with fixation pin.

REMOVAL OF IMPLANT If removal of the Stratis implant is necessary, locate the transverse tunnel in which the fixation pin has been implanted. Insert the threaded end of the fixation pin removal tool at the angle used to insert the pin; engage the threads. Once engaged, gently turn the fixation pin removal tool clockwise until the tool is seated in the fixation pin. Pull the fixation pin straight out with firm lateral traction. The pin’s ribbed press fit design will provide some resistance when being removed. Once the fixation pin is removed, gently pull on the graft ends to deliver the graft block into the joint. If the graft block cannot be delivered through the tibial tunnel, grab the distal end of the graft block with a snap inserted through the medial portal. Once firmly grasped, the graft block and graft can be delivered from the intraarticular space through the medial portal with gentle traction while turning the graft block clockwise or counter-clockwise.

PEARLS AND PITFALLS

FIG. 34-19 Fixation pin advanced through upper eyelet of graft block.

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1 The choice of the size of the graft block is entirely up to the surgeon. Most surgeons use the 25-mm block and drill between 30 and 35 mm (we prefer 32 mm). This ensures at least 20 mm of graft in the femoral tunnel. Note that the amount of graft needed in the femoral tunnel was based on initial studies of bone–tendon–bone and interference screws. It was not based on healing of the graft, but rather on pullout strength. Because this device’s pullout strength is not based on length of the femoral tunnel, we believe that 20 mm of graft in the tunnel is more than biologically appropriate for healing.

Stratis ST Femoral Fixation System If you decide to drill deeper or use the 35-mm device, note that as you drill deeper, you lose more lateral wall depth due to the flare of the femur. This may affect the amount of depth available for the transverse locking pin. 2 If you are drilling the femoral tunnel through the tibial tunnel (i.e., transtibial) we suggest that you flex the knee to 90 degrees. This accomplishes two things: First, it brings the point at which the transverse drill engages the lateral femoral cortex closer toward the mid-longitudinal axis, thereby maximizing lateral depth and limiting the chance of drill skiving. Secondly, it makes the drill more likely to engage the femoral flare and thereby increases lateral wall depth. Due to the unique anatomy of the distal femur, the more the knee is flexed, the more lateral depth is gained as you move the contact point off the femoral shaft and onto the femoral flare. In addition the anterior aspect of the femoral flare has more lateral wall depth than the posterior.26 3 Because the average intraarticular length of the ACL is about 25 mm, if the 35-mm graft block is used, you may encounter difficulty transferring the graft block through the tibial tunnel, across the joint, and into the femoral tunnel, as the tunnels may not perfectly align. If this occurs, flex the knee to 70 degrees and begin to insert the graft block into the femoral tunnel; once it is inserted 5 mm or so, you can extend the knee back to 90 degrees and insert the graft block fully. This technique may also be used for insertion of the tunnel guide. 4 When inserting the transverse drill sleeve onto the outrigger, it should be slid down firmly but easily. Hold on to the colored handle and not the outrigger when doing this. If you hold the outrigger and push it in with your thumb (syringe technique), you have the very slight possibility of splaying the outrigger like a wishbone and causing it to go off-axis. Although this has not occurred clinically, its theoretical possibility suggests the avoidance of this technique. 5 The transverse drill is stepped in design to accommodate the shape of the transverse locking pin. The tip of the drill has a sharp, brad point. When drilling, use high RPMs and low pressure (standard trauma technique). The first part of the drill will go quickly, and then the stepped portion engages the lateral cortex. Be patient, slightly increase your pressure, and keep up the RPMs; it will then capture and seat. Remove the drill with the power on. Do not pump back and forth within the tunnel because you do not want to inadvertently enlarge it. The drilling of the transverse tunnel, although meticulously described, takes about 10 seconds.

34

6 The pin inserter has a snug fit onto the transverse pin. Once the pin is inserted, pull down on the graft and graft block inserter to lock the transverse pin in place. A mallet can be used to back-tap the base of the pin inserter, quickly disengaging the assembly. After removing the pin inserter, a blunt tap can be used to push the pin to the correct depth. 7 We have performed the Stratis ST femoral fixation using the standard transtibial as well as medial portal femoral techniques and have noted that in the latter technique, there is sufficient lateral wall depth to capture the locking pin. Once again, this is a result of the unique shape of the distal femur in the hyperflexed position. 8 After we drill the transverse tunnel, we partially insert the switching stick. Once the tunnel guide/outrigger is removed, we fully seat the switching stick. Next, we use the arthroscope to look up the femoral tunnel to confirm the drilling. We leave the switching stick across the tunnel as we insert the graft–graft block construct. As we insert it farther into the femoral tunnel, the graft block hits the switching stick. We then back out the switching stick about 1.5 cm, fully seat the graft block, and then fully reinsert the switching stick to confirm alignment. 9 When preparing the graft, the ends are whipstitched and subsequently passed through the lower eyelet of the graft block. However, the end of the prepared graft may be too large to easily pass through the eyelet due to the added bulk of the whipstitched end. Therefore we recommend passing the graft one limb at a time through the eyelet and then preparing the ends of the graft with a whipstitch.

References 1. Owings MF, Kozak LJ. Ambulatory and inpatient procedures in the United States, 1996. Vital Health Stat 1998;139:1–119. 2. Shelbourne KD, Gray T. Anterior cruciate ligament reconstruction with autogenous patellar tendon graft followed by accelerated rehabilitation. A two- to nine-year follow up. Am J Sports Med 1997;25:786–795. 3. Buss DD, Warren RF, Wickiewicz TL, et al. Arthroscopically assisted reconstruction of the anterior cruciate ligament with use of autogenous patellar-ligament grafts. Results after twenty-four to forty-two months. J Bone Joint Surg 1993;75A:1346–1355. 4. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. J Bone Joint Surg 2004;86A:2143–2155. 5. Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:722–728. 6. Ejerhed L, Kartus J, Sernert N, et al. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with a two-year follow-up. Am J Sports Med 2003;31:19–25.

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Anterior Cruciate Ligament Reconstruction 7. Jansson KA, Linko E, Sandelin J, et al. A prospective randomized study of patellar versus hamstring tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:12–18. 8. Laxdal G, Kartus J, Hansson L, et al. A prospective randomized comparison of bone-patellar tendon-bone and hamstring grafts for anterior cruciate ligament reconstruction. Arthroscopy 2005;21:34–42. 9. Shaieb MD, Kan DM, Chang SK, et al. A prospective randomized comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:214–220. 10. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 11. Beynnon BD, Johnson RJ, Abate JA, et al. Treatment of anterior cruciate ligament injuries, part I. Am J Sports Med 2005;33:1579–1602 [review]. 12. Marder R, Raskind J, Carroll M. Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction: patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478–485. 13. Herrington L, Wrapson C, Matthews M, et al. Anterior cruciate ligament reconstruction, hamstring versus bone-patella tendon-bone grafts: a systematic literature review of outcome from surgery. Knee 2005;12:41–50 [review]. 14. Simonian PT, Erickson MS, Larson RV, et al. Tunnel expansion after hamstring anterior cruciate ligament reconstruction with 1-incision EndoButton femoral fixation. Arthroscopy 2000;16:707–714. 15. Roe J, Pinczewski LA, et al. A 7-year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction: differences and similarities. Am J Sports Med 2005;33:1337–1345.

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16. Hamner DL, Brown CH Jr, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81:549–557. 17. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg 1984;66A:344–352. 18. Fahey M, Indelicato PA. Bone tunnel enlargement after anterior cruciate ligament replacement. Am J Sports Med 1994;22:410–414. 19. Fauno P, Kaalund S. Tunnel widening after hamstring anterior cruciate ligament reconstruction is influenced by the type of graft fixation used: a prospective randomized study. Arthroscopy 2005;11:1337–1341. 20. Barrett GR, Papendick L, Miller C. Endobutton button endoscopic fixation technique in anterior cruciate ligament reconstruction. Arthroscopy 1995;11:340–343. 21. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 22. Fabbriciani C, Mulas PD, Ziranu F, et al. Mechanical analysis of fixation methods for anterior cruciate ligament reconstruction with hamstring tendon graft. An experimental study in sheep knees. Knee 2005;12:135–138. 23. Studies on file. Littleton, MA, Scandius Biomedical. 24. Frank DA, Altman GT, Re P. Hybrid anterior cruciate ligament reconstruction: introduction to a new technique for anatomic anterior cruciate ligament reconstruction. Arthroscopy 2007; In Press. 25. Solman CG, Pagnani MJ. Hamstring tendon harvesting: reviewing anatomic relationships and avoiding pitfalls. Orthop Clin N Am 2003;34:1–8. 26. Re P. Unpublished data.

Pinn-ACL CrossPin System for Femoral Graft Fixation INTRODUCTION Graft fixation has been considered the weak link in the early postoperative period, especially with the soft tissue grafts. Initial fixation requires sufficient fixation strength during the rehabilitation period while the graft incorporates into the bone tunnels. Several techniques have been used for fixing hamstring grafts. Interference screw fixation for quadrupled hamstring grafts has failure strengths that may not be adequate for daily activities and a modern rehabilitation program1; suspension techniques are related to tunnel enlargement and the so-called “bungee effect.”2–4 A recent study demonstrated that four-bundle hamstring grafts fixed with modern techniques produced higher stability rates than bone–patellar tendon–bone (BPTB) reconstructions.5 Transfixation pin fixation techniques were developed to improve femoral graft fixation; these techniques put a pin across the femur traversing the femoral tunnel. Within the transverse femoral tunnel, the pins either penetrate the graft, as with Rigidfix (Mitek, Ethicon, Westwood, MA); the two bundles of the hamstring graft fold around the pin to create a quadrupled graft, as with Bio-TransFix (Arthrex, Naples, FL), Cross-Screw (Stryker, Kalamazoo, MI) and Bone Mulch (Arthrotek, Warsaw, IN); or the two bundles are looped through a graft harness that a pin transverses to create a quadrupled graft (ConMed-Linvatec, Largo, FL). Femoral fixation of hamstring tendon grafts using transfixing pins is an accepted technique that yields

excellent biomechanical properties with failure loads over 800N,1,6,7 which clearly surpasses the 500N accepted to adequately follow an aggressive rehabilitation protocol8,9 and has demonstrated results in clinical trials comparable with other fixation methods.10–13 The ConMed-Linvatec Pinn-ACL CrossPin System is designed to provide transverse femoral fixation in anterior cruciate ligament (ACL) reconstruction using a soft tissue graft. With existing systems, transverse femoral fixation was a blind procedure, but this surgical technique and the implant’s innovative design allow the surgeon to visualize the transverse tunnel and exact point of femoral fixation. With this system the graft is suspended in a harness and the pin transfixes the harness, not the graft. Laboratory testing has showed greater than 1700N pullout strength,14 which is superior to that of other available designs.1,6,7

35 CHAPTER

Arturo Almazan Donald H. Johnson

INSTRUMENTS AND IMPLANT DESIGN The Pinn-ACL CrossPin system for femoral graft fixation includes the implants and instrumentation to ensure accurate transverse fixation of the graft. The implant consists of two parts, the graft harness and the cross-pin implant (Fig. 35-1). The graft harness is composed of selfreinforced poly-L-lactic acid (PLLA), it has an eyelet in which the cross-pin locks, it also has a closed loop of high-strength Dyneema suture in which the graft sits and folds, and in its proximal aspect it has a lead suture for graft construct

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FIG. 35-1 CrossPin system: graft harness (purple) and cross-pin, both with their leading sutures.

passing. The graft harness is available in 8- and 9-mm diameters. The cross-pin implant is also composed of self-reinforced PLLA, is available in three different lengths (40, 45, and 50 mm), and has a lead suture in its tip for implant passing. A disposable transverse cannula fits in the blue frame and slides over the drill bit to maintain the entrance of the transverse tunnel as opened and accessible. The U-Guide is an external aimer with two components—the main blue frame and the positioning rod, which fit in the tunnels—and is available in 8 and 9 mm. A specially designed drill bit with two different diameters is used to create the transverse tunnel. This drill bit is the same for every procedure regarding the cross-pin implant length. Being a transverse fixation system, the tip of the drill bit engages in the tip of the positioning rod to ensure the engagement of the implants (Fig. 35-2).

SURGICAL TECHNIQUE WITH HAMSTRING TENDONS

when folded, a 10-cm-long final graft construction is desired. The free grafts are taken to the Grafix Prep Table for preparation. Both tendons are measured and cut to the desired length (20 to 22 cm), and then muscle is removed with an osteotome or a periosteal elevator. Once cut and cleaned, each end of the individual graft tendon is whipstitched approximately 35 to 40 mm from the end with a #2 nonabsorbable suture. If the surgeon plans to use the SE Graft Tensioner for tibial fixation, the graft’s bundles must be identified. This is easily accomplished by applying one knot to the semitendinosus sutures and two to the gracilis or by using a surgical marker pen. Using the graft sizing block, the entire graft bundle diameter is measured. It is important to take measurements of the femoral and tibial ends (Fig. 35-3); these diameters will determine the proper sizes of the cross-pin graft harness and tunnel. The graft harness size (8 or 9 mm) should always be selected based on the diameter of the femoral end of the graft. Not infrequently, the entire graft size is not uniform; usually the tibial end increases 1 mm because of the morphology of the tendon and the placed sutures. If this is the case, the cross-pin graft harness must match the femoral graft diameter. For tunnel creation, two different drill bits will be used, with the smaller drill bit for the femoral tunnel and the larger for the tibial tunnel. To load the graft strands into the graft harness (Fig. 35-4), place the graft harness onto the harness holder accessory and pass the graft strands individually through the continuous suture loop on the graft harness.

Notchplasty and ACL Stump Removal The ACL stump is removed with the shaver. The notchplasty is large enough to accommodate the graft; this is

Graft Harvesting and Preparation The semitendinosus and gracilis tendons are harvested in the usual fashion. Each tendon must be at least 20 cm long because,

FIG. 35-3 Measure the diameter of the femoral and tibial ends.

FIG. 35-2 Cross-pin drill bit as it engages the positioning rod.

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FIG. 35-4 Graft mounted in the harness.

Pinn-ACL CrossPin System for Femoral Graft Fixation usually possible by just removing the soft tissues on the lateral wall of the notch with the shaver or a curette. Sometimes in chronic cases in which stenotic bone is found, notchplasty will include some bone resection.

Tibial and Femoral Tunnel Creation The Pinn-ACL tibial guide, set at 55 degrees, is inserted into the knee through the medial working portal. The tip of the guide is placed in the posterior aspect of the tibial ACL stump following an imaginary line along the posterior border of the lateral meniscus anterior horn and centered in the midline of the joint. The guide pin should enter the tibia 5 cm below the medial joint line and 2 to 3 cm medial to the anterior tibial tuberosity in a position adjacent to the medial collateral ligament; this alignment will create a tibial tunnel that allows a more oblique femoral tunnel, usually around the 65-degree angle.15,16 The guide pin is advanced into the tibia, and arthroscopic visualization is used to check the correct position of the guide pin in the joint. An AccuDrill reamer corresponding to the graft’s tibial size is used to create the tibial tunnel. Select the correct Bullseye guide so to leave 1 to 2 mm of cortical back wall in the femoral tunnel. This selection is made according to the femoral end diameter of the folded graft. The Bullseye guide is inserted into the joint through the tibial tunnel. The knee is slightly extended, and the tip of the guide is directed toward the posterior femoral cortex, trying to aim to the 10-o’clock position for the right knee and 2-o’clock position for the left knee. Once the tip of the guide is hooked in the femoral back wall, the knee is bent to 90 degrees, and the graft-passing guide pin is inserted through the handle of the Bullseye guide and drilled until it exits the lateral portion of the femur and skin. Leaving the graft-passing guide pin in place, the femoral Bullseye guide is taken out, its tip is disengaged, and it is turned 90 degrees toward the posterior cruciate ligament (PCL). A C-Reamer or Badger drill of the appropriate size (8 or 9 mm) is used to create the femoral tunnel. The tunnel length of the femoral socket should be no less than 30 mm (35 mm is recommended). The femoral drilling must be visualized with the arthroscope to ensure the tunnel position and integrity of the posterior back wall.

35

With the U-Guide assembled, insert the positioning rod over the graft-passing guide pin, through the tibial tunnel, and completely into the femoral socket. The positioning rod has laser-etched marks to enable the surgeon to check its penetration. If the positioning rod is fully inserted in the femoral tunnel, the laser marks must match the tunnel length; otherwise it is not fully inserted or the tunnel depth was not accurate. Remove the graft-passing guide pin from the femoral tunnel. After the U-Guide is fully inserted into the tunnels, rotate the U-Guide body until the black transverse cannula that is mounted on the U-Guide body is directed toward the lateral condyle. The transverse tunnel will be drilled from the lateral to the medial condyle.

Cross-Pin Implant Selection With the U-Guide body in the correct orientation, insert the cross-pin drill bit into the drill guide aperture and identify the entrance point of the transverse tunnel. With the tip of the cross-pin drill bit touching the skin, use a scalpel to create a small, 3- to 5-mm incision to assist the passage of the drill bit through the soft tissue in order to make contact with lateral femoral cortex. To identify the appropriate length of cross-pin to be used, utilize the U-Guide and cross-pin drill bit as a caliper to first determine the length of the cortical side of the transverse tunnel (i.e., the distance from the lateral cortex of the femur to the lateral wall of the femoral tunnel). To measure this distance, firmly press the cross-pin drill bit against the cortical surface, without drilling, and read the laser-etched depth markings where the drill bit enters the drill guide aperture (Fig. 35-5). This measurement is important in selecting the appropriatesized cross-pin implant for cortical side fixation.

U-Guide Position and Cortical Length Measurement Based on the diameter of the femoral tunnel, select the appropriate positioning rod size (8 or 9 mm) and assemble it onto the U-Guide. Slide the black disposable transverse cannula, which is packaged with the graft harness, onto the U-Guide body.

FIG. 35-5 The measurement on the transverse drill bit indicates the correct size of the cross-pin implant. (Courtesy of ConMed-Linvatec.)

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Anterior Cruciate Ligament Reconstruction Each cross-pin has a cortical length designed to occupy the cortical side of the transverse tunnel, the available cortical lengths being 15, 20, and 25 mm. The proper length of the cross-pin is that in which the cortical length is less than or equal to the measured cortical tunnel length. After the measurement is taken, drill the transverse tunnel until the drill bit stops against the U-Guide body. As you pull out the drill from the tunnel by hand, push the black transverse cannula into the transverse tunnel to prevent soft tissues from entering the transverse tunnel (Fig. 35-6). Note: The use of the transverse cannula is optional. The purpose of the cannula is to maintain the opening of the transverse tunnel in the event the transverse opening cannot be located. Before removing the U-Guide, reinsert the graftpassing guide pin until it exits the lateral femur and skin, and then remove the U-Guide from the knee by sliding it over the guide pin as it exits the femoral and tibial tunnels.

FIG. 35-6 The transverse cannula remains in the transversal tunnel, facilitating instruments and device entrance. (Courtesy of ConMedLinvatec.)

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Graft Passing Draw the hamstring graft construct into the knee using the graft-passing guide pin. Pass the lead suture of the graft harness through the eyelet of the graft-passing guide pin and, while maintaining lateral-to-medial alignment of the axis of the eyelet in the graft harness, pass the graft construct into the tibial tunnel. It is very important to maintain the graft harness alignment; the eyelet on it must be parallel to the transverse femoral drill (Fig. 35-7). As the graft harness enters the joint space in the intracondylar notch, use an arthroscopic probe (if necessary) to maintain the eyelet orientation lateral to medial as it passes into the femoral tunnel (Fig. 35-8). Pull firmly on the graft construct until it is fully seated in the femoral socket. Place a sheathed scope into the black transverse cannula to view the full insertion and alignment of the axis of the graft harness eyelet with the axis of the transverse tunnel (Fig. 35-9).

FIG. 35-7 The harness lead suture is mounted in the graft-passing guide pin. (Courtesy of ConMed-Linvatec.)

Pinn-ACL CrossPin System for Femoral Graft Fixation

35

A sheathed scope should be placed into the black transverse cannula to view the lead suture passing through the eyelet of the graft harness (Fig. 35-10). Gently pull the cross-pin lead suture until it enters the black transverse cannula and the tunnel opening. Insert the cross-pin driver into the proximal end of the implant (Fig. 35-11, A), and tap the driver with a mallet, advancing the implant until it stops. After the cross-pin is fully seated, disengage the driver and ensure the cross-pin implant is flush with or slightly below the cortical surface (Fig. 35-11, B) by palpating the proximal end of the cross-pin at the insertion site. Apply tension to the graft construct by pulling the tibial sutures to check femoral fixation. Finally, pull on one end of the lead suture attached to the cross-pin to remove the suture from the device. Additionally, pull on one end of the lead suture attached to the graft harness to remove its suture (Fig. 35-12). FIG. 35-8 Arthroscopic view of the graft harness as it enters the femoral tunnel.

Tibial Fixation

Graft Fixation

The recommended tibial fixation is the ConMed-Linvatec BioScrew Xtralok interference screw. Tensioning of graft can be conducted using the ConMed-Linvatec SE Graft Tensioner System.

With the graft fully seated in the femoral tunnel and the graft harness adequately oriented, pass the graft-passing guide pin through the black transverse cannula and the eyelet of the graft harness into the medial portion of the transverse tunnel by hand. When the graft-passing guide pin will advance no further, drill the graft-passing guide pin until it exits the medial femur and skin. To confirm proper placement of the graft-passing guide pin, pull tension on the graft construct to ensure the graft-passing guide pin intersects the graft harness construct. Pass the lead suture of the cross-pin implant through the eyelet of the graftpassing guide pin. Remove the graft-passing guide pin from the transverse tunnel by pulling by hand from the medial side until it fully exits the knee. The lead suture of the cross-pin implant should pass through the transverse tunnel and the graft harness and exit on the medial side of the knee.

FIG. 35-9 Use of an arthroscope in the transverse tunnel to verify that the harness is centered in the tunnel. (Courtesy of ConMed-Linvatec.)

TIPS AND TRICKS The Pinn-ACL CrossPin system for femoral fixation, like other transfixation devices, has a steep learning curve, but the main advantage of this system is that it is the only one providing endoscopic visualization of the exact point of femoral fixation. Several steps, which may be easily missed, facilitate the procedure as follows:

 The positioning rod is only 8 and 9 mm; for 7-mm grafts, use the 8-mm rod.

 When inserting the positioning rod in the femoral tunnel, it is useful to gently tap it to ensure it is fully inserted.

FIG. 35-10 Use of an arthroscope in the transverse tunnel to verify that the implant’s lead suture passes through the harness eyelet. (Courtesy of ConMed-Linvatec.)

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FIG. 35-12 Final view of the femoral fixation. The cross-pin engages the graft harness. (Courtesy of ConMed-Linvatec.)

 The transverse drill bit always must be removed by hand, FIG. 35-11 A, Tap the implant’s driver to insert the cross-pin into the transverse tunnel. B, Insert the implant until it is flush with the lateral cortex of the femur. (Courtesy of ConMed-Linvatec.)

if the power drill is used; the black cannula will engage in the drill bit spinning or braking.

 Before removing the U-Guide, reinsert the graft-passing guide pin through the positioning rod.

The laser mark must match the previously drilled depth.

 Always remove the graft-passing guide pin from the femoral tunnel before transverse drilling; otherwise the transverse drill bit may not pass through the U-Guide or, if it does, a false way will be created.

 Do not forget to measure the length of the cross-pin implant before drilling the transverse tunnel, as this measurement will give you the proper size of the implant to use.

 The length measured in the transverse drill bit is the size of the cross-pin implant to use.

 When drilling the transverse tunnel, ensure the black transverse cannula is seated in the U-Guide, not in the skin incision. If it is in the incision when the power drill is activated, the black cannula will engage in the drill bit spinning or braking. 258

 It is useful to introduce the shaver into the transverse tunnel entrance to remove the soft tissues that may interfere with scope visualization.

 Do not try to introduce the scope in the U-Guide if it is not removed first. The distance between the lateral border of the U-Guide and the transverse tunnel entrance is larger than the scope tip.

 The shaver can be used to remove soft tissues from the transverse tunnel; this maneuver may facilitate the introduction of the transverse cannula.

 The clue for success with this technique is that the graft harness eyelet must be parallel to the transverse tunnel. To accomplish this, the eyelet must be oriented so that it enters the tibial tunnel. It is extremely difficult to rotate it when it is within the bone tunnels, but it is easy to control rotation of the graft if the surgeon holds it in

Pinn-ACL CrossPin System for Femoral Graft Fixation hand with the bundles separated in two pairs (Fig. 35-13). As the lead suture of the graft harness is pulled out and the graft prepares to enter the tibial tunnel, the surgeon can rotate the graft to match the eyelet–transverse tunnel orientation. Tension in the lead suture of the graft harness must be maintained while it enters the tunnels as the surgeon controls graft rotation by hand. Arthroscopic visualization is very helpful. If the surgeon observes that the graft harness is slightly rotated (less than 20 degrees), sometimes the harness can be rotated using the arthroscopic probe. If it is badly rotated (greater than 20 degrees), it is better to take the graft out and correct alignment.

 Once the graft harness enters the femoral tunnel, change the arthroscope to the transverse tunnel to visualize how it sits up in the tunnel. The surgeon must observe that the harness eyelet is centered in the transverse tunnel (Fig. 35-14); this will allow the cross-pin device to fit into the harness eyelet.

FIG. 35-13 Spreading the bundles of the graft helps control rotation as it enters the tunnels.

35

 If there is any doubt regarding whether the cross-pin was fully inserted until flush with the femoral cortex, the scope can be placed again through the skin incision to check the cross-pin position.

TROUBLESHOOTING During our learning curve with the CrossPin system, we had only two intraoperative incidents. In one case we did not remove the guide pin from the positioning rod, and the cross-pin drill bit was forced and created a false way. When this was recognized, the guide pin was removed; the drill bit was introduced again, creating a correct transverse tunnel; and the rest of the case followed with no problems. In the second case, the cross-pin implant was sunken into the lateral femoral condyle; to avoid this incident, we recommend prior definite implant impaction to insert the driver through the skin incision and sit it on the femoral lateral cortex, and then put a mark in the driver using a marker pen. This mark will assist in recognizing the exact depth of implant insertion. The opposite can happen, leaving the implant too proud on the lateral femoral cortex; both incidents have already been reported with the use of transfixation pins.17,18 Our results with the CrossPin femoral fixation are encouraging thus far; we have 6 months of follow-up and all patients have full range of motion, no Lachman or pivot-shift signs, KT-1000 manual maximum side-to-side differences of 1 mm, and no radiological signs of tunnel enlargement.

VIDEO TECHNIQUE A presentation of the CrossPin system technique is available in the DVD that accompanies this textbook.

References

FIG. 35-14 The graft harness eyelet is centered in the transverse tunnel.

1. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 2. Uchio Y, Ochi M, Sumen Y, et al. Mechanical properties of newly developed loop ligament for connection between the EndoButton and hamstring tendons: comparison with Ethibond sutures and Endobutton tape. J Biomed Mater Res 2002;63:173–181. 3. Hoher J, Scheffler SU, Withrow JD, et al. Mechanical behavior of two hamstring graft constructs for reconstruction of the anterior cruciate ligament. J Orthop Res 2000;18:456–461. 4. Hoher J, Livesay GA, Ma CB, et al. Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation. Knee Surg Sports Traumatol Arthrosc 1999;7:215–219. 5. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar tendon graft and fixation type. Arthroscopy 2005;21:1202.

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Anterior Cruciate Ligament Reconstruction 6. Ahmad CS, Gardner TR, Groh M, et al. Mechanical properties of soft tissue femoral fixation devices for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:635–640. 7. Clark R, Olsen RE, Larson BJ, et al. Cross-pin femoral fixation: a new technique for hamstring anterior cruciate ligament reconstruction of the knee. Arthroscopy 1998;14:258–267. 8. Howell SM, Hull ML. Aggressive rehabilitation using hamstring tendons: graft construct, tibial tunnel placement, fixation properties, and clinical outcome. Am J Knee Surg 1998;11:120–127. 9. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg 1984;66A:344–352. 10. Wilcox JF, Gross JA, Sibel R, et al. Anterior cruciate ligament reconstruction with hamstring tendons and cross-pin femoral fixation compared with patellar tendon autografts. Arthroscopy 2005;21:1186–1192. 11. Harilainen A, Sandelin J, Jansson KA. Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33.

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12. Fabbriciani C, Milano G, Mulas PD, et al. Anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendon graft in rugby players. Knee Surg Sports Traumatol Arthrosc 2005;13:2–7. 13. Wolf EM. Hamstring anterior cruciate ligament reconstruction using femoral cross-pin fixation. Oper Tech Sports Med 1999;7:214–222. 14. ConMed-Linvatec, Pinn-ACL CrossPin System [company brochure] ConMed-Linvatec; 2005. 15. Johnson D. Anterior cruciate reconstruction using hamstring grafts fixed with bioscrews and augmented with the EndoPearl. Tech Orthop 2005;20:264–271. 16. Howell SM, Gittins ME, Gottlieb JE, et al. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. 17. Pelfort X, Monllau JC, Puig L, et al. Iliotibial band friction syndrome after anterior cruciate ligament reconstruction using the Transfix device: report of two cases and review of the literature. Knee Surg Sports Traumatol Arthrosc 2006;14:586–589. 18. Marx RG, Spock CR. Complications following hamstring anterior cruciate ligament reconstruction with femoral cross-pin fixation. Arthroscopy 2005;21:762.e1–762.e3.

TransFix Anterior Cruciate Ligament Femoral Fixation BACKGROUND More than 100,000 anterior cruciate ligament (ACL) reconstructions are estimated to be performed annually in the United States.1,2 There has been a tremendous amount of research on both graft selection and fixation methods.3–5 The increased use of soft tissue grafts and the concern regarding soft tissue interference screw fixation (e.g., graft pullout, slippage, damage) have led to the development and use of femoral cross-pin fixation in ACL reconstruction. One successful technique for cross-pin fixation is the TransFix ACL reconstruction technique (Arthrex, Naples, FL). Unlike interference screw fixation, which is dependent upon screw geometry, bone density, and interface gap, the fixation strength of the TransFix is limited only by the strength of the graft and the device itself (size, geometry, and material composition). The mode of failure of the TransFix pin during biomechanical studies has consistently been bending and breakage, unlike the evidence of graft slippage for interference screw constructs.

BIOMECHANICAL AND CLINICAL RESULTS The Arthrex TransFix implant is made of titanium, and the Bio-TransFix implant is made of poly-L-lactic acid (PLLA), as shown in Fig. 36-1. In vivo, the Bio-TransFix implant hydrolyzes into lactic acid, which is then

metabolized into CO2 and H2O. A proprietary degradation study of the Bio-TransFix demonstrated that it does not lose shear strength through 52 weeks. Several studies have shown that the TransFix and Bio-TransFix have significantly better structural properties for maximum load, stiffness, strength, and slippage of soft tissue grafts as compared with interference screw fixation and other cross-pin fixation techniques. Also, because of the fixation technique, the potential for tunnel widening is significantly decreased and the strength of the graft is compromised much less than that from interference screw fixation. Fabbriciani et al used the TransFix system in conjunction with fresh, ovine, doubled Achilles tendons and ovine femurs.5 Cyclical loading comparisons of bioabsorbable and metal RCI screws (Smith & Nephew, Andover, MA), the LINX HT (Mitek, Norwood, MA), and the TransFix implant showed significantly lower mean values of graft elongation for the TransFix construct (1.5
0.1 mm) over 1000 cycles. The maximum load to failure (LTF) for the TransFix was 890N
175N, which, unlike the other devices in the study, is comparable to that of the intact ovine ACL (725N
77N). Becker et al showed that the stiffness of the TransFix construct (184 N/mm) approximates the stiffness of the human ACL (242 N/mm, as reported by Woo et al6) and provides significantly greater ultimate strength than interference screw fixation.7 This study compared three fixation methods using a porcine femur model: (1) TransFix fixation of a quadruple tendon, (2) 8-  20-mm

36 CHAPTER

Brian P. McKeon

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Anterior Cruciate Ligament Reconstruction described their postoperative knees to be normal or near normal. The 27 patients had a mean KT-1000 side-to-side laxity difference of 1.5 mm at follow-up. (Ahmad reports that greater than 5 mm may be considered clinical failure.8) Recently, Harilainen et al12 showed no significant difference in IKDC scores at 2-year follow-up for TransFix cross-pin fixation versus metal screw fixation. In this controlled prospective randomized study, 85% of the TransFix group and 73% of the screw patients were in the IKDC A or B categories.

SURGICAL TECHNIQUE FIG. 36-1 The Arthrex TransFix implant is made of titanium, and the Bio-TransFix implant is made of poly-L-lactic acid (PLLA).

biodegradable interference screw fixation of a quadruple tendon, and (3) 8-  20- mm titanium screw fixation of a patellar tendon–bone graft using a porcine femur model. Interference screw fixation of the patellar tendon and quadruple tendon resisted only 59% and 37%, respectively, of the pullout strength of the TransFix (1303N
282N). The TransFix had significantly less construct displacement during cyclical loading than the interference screw/quadruple graft construct. Ahmad et al demonstrated that interference screw fixation and the Rigidfix cross-pin technique were inferior to the Bio-TransFix and the Endobutton for graft slippage during cyclical loading and ultimate LTF.8 After 1000 cycles, the graft displacement for the Bio-TransFix was 1.13 mm compared with greater than 5 mm for the interference screw and Rigidfix. This study also showed significantly greater LTF of the Bio-TransFix (746N
119N) as compared with the interference screw technique (539N
114N). As these and other studies have demonstrated, the use of the TransFix system offers considerable advantages compared with other femoral fixation systems in terms of yield load, stiffness, and deformation and elongation under cyclical loading. These results offer stable fixation of the graft during the postoperative period, before graft healing has occurred. The inherent rigidity of the TransFix limits graft-tunnel motion during physiological loading. Intratunnel motion has been associated with tunnel widening.9 Fauno and Kaalund reported a significant reduction in tunnel widening in the femur when TransFix was used compared with Endobutton fixation at 1-year follow-up for a prospective randomized study.10 Unlike interference screw techniques, in which the graft is squeezed and possibly damaged during screw insertion, graft strength is maximized with the TransFix technique. In 1998, Wolf11 reported his initial results with the TransFix fixation. Eighty-eight percent of patients at follow-up 262

The TransFix technique requires that a 3-mm drill pin be passed from lateral to medial. Although no neurovascular complications have been reported, theoretically the medial (and lateral) neurovascular structures are at risk. The author’s lab has shown that a defined “safe zone” exists in which a distal femoral cross-pin can be reliably placed without damaging the local neurovascular structures.13 In this anatomical cadaveric study, the absolute neurovascular safe zone during cross-pin guidewire placement is from þ20 degrees (0 degrees equals “parallel to the floor” line) and –40 degrees (lowering the guide more posteriorly) (Fig. 36-2). The TransFix technique is designed for soft tissue grafts such as hamstring autograft or tibialis tendon allograft. The author prefers tibialis tendon allograft and has performed more than 300 TransFix ACL reconstructions with this particular graft. A stepwise approach is as follows: 1 Position the patient supine, and place the patient under general anesthesia. Examine both knees, and place a tourniquet and thigh holder on the consented extremity. 2 Perform routine diagnostic arthroscopy with a standard two anterior portal technique. Complete all meniscal and articular cartilage procedures prior to notchplasty. 3 Prepare the tibialis graft with a running or Krackow locking stitch,14 and size it to the nearest-millimeter diameter (Fig. 36-3). Tip 1: Make sure the graft runs easily through the selected diameter. One advantage of a tibialis graft is that the surgeon can select or trim the graft to the desired size. The completed graft is placed in a moist sponge that has been soaked in antibiotic solution. 4 Complete the tibial tunnel through a small anterior medial tibial incision using a posterior cruciate ligament (PCL) referencing guide (Fig. 36-4). 5 Place the foot in a sterile basin with the knee at about 90 degrees of flexion.

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36

FIG. 36-2 The absolute neurovascular “safe zone” during cross-pin guidewire placement is from þ20 degrees (0 degrees equals “parallel to the floor” line) to –40 degrees (lowering the guide more posteriorly).

a depth of 30 mm to avoid reaming out through the femoral cortex. 8 Remove the Beath pin. Insert the matched TransFix tunnel hook through the tibial tunnel, and position it in the femoral socket (Fig. 36-5). A small lateral stab incision through the iliotibial band (ITB) allows for the guide pin sleeve to be advanced directly to bone. If the guide pin’s laser line is exposed, use a 50-mm TransFix pin. The author has used a 50-mm pin only once in more than 300 cases. FIG. 36-3 Prepare the tibialis graft with a running or Krackow locking stitch, and size it to the nearest-millimeter diameter.

Tip 2: The knee flexion angle must be maintained until the TransFix is implanted.

Tip 4: Do not overtighten the drill guide on the lateral cortex. This causes the sleeve to skive along the metaphysis and throw off the alignment of the guide. The sleeve should rest lightly on the bone.

6 Use a transtibial femoral ACL drill guide (TTG) to create a 1- to 2-mm “back wall.”

9 Drill a 3-mm guide pin medially through the guide sleeve and tunnel hook. In general, the guide pin should be directed parallel to the floor or anteriorly.13

Tip 3: The TTG should easily be placed in the over-thetop position. If not, the tibial tunnel may be too anterior. A Beath pin is drilled through the distal cortex but not through the skin.

Tip 5: Do not push hard on the TransFix guide pin when drilling. This can cause the trocar tip to skive along the metaphysis and throw off the aim. The TransFix guide pin is threaded and will ease across the femur.

7 Complete the selected femoral tunnel, reaming to a depth of 40 mm. In small patients, the author accepts

Tip 6: The 3-mm guide pin should easily pass back and forth, ensuring a smooth passage through the tunnel 263

Anterior Cruciate Ligament Reconstruction

FIG. 36-6 Drill the 5-mm broach with a stop collar over the 3-mm guidewire.

hook. Pass the guidewire back and forth several times manually until it glides easily.

FIG. 36-4 Complete the tibial tunnel through a small anterior medial tibial incision using a posterior cruciate ligament referencing guide.

10 Drill the 5-mm broach with a stop collar over the 3-mm guidewire (Fig. 36-6). Note: The calibration numbers on the drill are used as a guide for subsequent implant insertion depth. For example, if the calibration shows 3 cm, the depth markings on the implant impactor should match at the time of final TransFix implantation. 11 Pass and deliver the nitinol wire out of the tibial tunnel. Pass the selected graft in a retrograde fashion (Fig. 36-7). Tip 7: The nitinol wire should glide back and forth very easily after seating the graft proximally. The kink in the wire from graft passage should be pulled medially to prevent capturing the implant on insertion. If the graft–tunnel interface is too tight, the graft will not be seated proximally. This will result in the nitinol wire breaking on implant insertion. The knee flexion angle at the time of reaming the femoral socket must be maintained. Tip 8: A blunt probe can be used to push the graft up the femoral tunnel to assist in seating the graft completely in the femoral socket.

FIG. 36-5 Remove the Beath pin. Insert the matched TransFix tunnel hook through the tibial tunnel, and position it in the femoral socket.

264

Tip 9 (the most critical): The implant should be advanced manually along the same direction as the nitinol wire. An assistant should confirm smooth glide of nitinol wire throughout the insertion. Hand-inserting the implant as far as possible allows for more surgeon/assistant feedback. If resistance to glide is noted with the nitinol wire,

TransFix Anterior Cruciate Ligament Femoral Fixation

36

14 Cycle the construct, and correct any roof or lateral wall impingement if necessary. 15 Secure the graft on the tibial side with a 35-mm deltatapered biointerference screw (Arthrex) (usually 2 mm greater in diameter than the tibial tunnel). If orifice fixation is desired, this can be achieved with the addition of a cancellous bone block15 or 20-mm femoral retroscrew (Arthrex) placed distal to the TransFix. Ishibashi et al demonstrated that proximal fixation resulted in reduced anteroposterior translation compared with more distal fixation.16 Anatomical fixation close to the joint line results in increased knee stability and graft isometry. Fixation of the graft in the tunnel by an interference screw or bone block also may mitigate synovial fluid infiltration into the tunnel.

TROUBLESHOOTING AND COMMON PROBLEMS FIG. 36-7 Pass and deliver the nitinol wire out of the tibial tunnel. Pass the selected graft in a retrograde fashion.

then the surgeon should immediately confirm proper implant orientation. 12 Seat the implant at the appropriate depth (match the calibration line to the reamer) with gentle taps using a mallet only after smooth passage of the wire is confirmed (Fig. 36-8). 13 Remove the nitinol wire in a medial direction.

FIG. 36-8 Seat the implant at the appropriate depth (match the calibration line to the reamer) with gentle taps using a mallet only after smooth passage of the wire is confirmed.

The tunnel hook jig cannot be passed into the tibial/ femoral socket: Confirm the sizes of the tunnel and tunnel hook. Always verify that the knee flexion angle is maintained after drilling the femoral socket. This ensures that no resistance will be encountered while passing the graft from the tibial to the femoral socket. The graft will not seat properly in the femoral socket: If the graft cannot be pushed up into the femoral socket with a blunt probe while the assistant pulls the nitinol wire, then the surgeon should resize the graft. The graft diameter is likely to be too large. Do not soak the graft in saline after sizing; often swelling can increase graft diameter. The graft can be trimmed, or in extreme cases, the femoral tunnel can be reamed up one size. Always make sure that the knee flexion angle is maintained after drilling the femoral socket. The nitinol wire does not glide very easily: Again, always make sure that the knee flexion angle is maintained after drilling the femoral socket. The graft is not seated proximally (see earlier). The TransFix implant is “trapping wire”: Confirm that the implant insertion angle is identical to that of the nitinol wire. The graft may not be seated proximally (see earlier). The nitinol wire breaks: This typically happens early in the insertion phase. Broken ends of wire can easily be removed from both medial and lateral directions. In general, this is because the graft is not seated enough proximally or the implant insertion angle is different from that of the guide pin/nitinol wire. Resize the graft, and reconfirm the correct angle of implant insertion. A portion of the wire will be left in the femur/implant if the wire breaks after the implant is seated. This situation is usually not a problem if the graft is secure, but it will be obvious on radiographs. 265

Anterior Cruciate Ligament Reconstruction The graft is severed upon implant insertion: The threads on the TransFix implant can injure the graft if it is countersunk in bone too far. Use another allograft if available, or suture the graft together (tubularize) and convert to using Endobutton fixation or soft tissue interference screw fixation.

CONCLUSION In summary, TransFix cross-pin fixation offers favorable strength and stiffness values as well as excellent early clinical results.

References 1. Brown CH, Carson EW. Revision anterior cruciate ligament surgery. Clin Sports Med 1999;18:109–171. 2. Orthopedic soft tissue repair. Norwalk, CT, 2005, Windhover Information. 3. Brand J, Weiler A, Caborn D, et al. Current concepts: graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 4. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 5. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction: part II: tibial site. Am J Sports Med 2003;31:182–188. 6. Woo SL, Hollis JM, Adams DF, et al. Tensile properties of the human femur-anterior cruciate ligament-tibia complex. The effects of specimen age and orientation. Am J Sports Med 1991;19:217–225.

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7. Becker R, Voight D, Starke C, et al. Biomechanical properties of quadruple tendon and patellar tendon femoral fixation techniques. Knee Surg Sports Traumatol Arthrosc 2001;9:337–342. 8. Ahmad CS, Gardner TR, Groh M, et al. Mechanical properties of soft tissue femoral fixation devices for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:635–640. 9. L’Insalata JC, Klatt B, Fu FH, et al. Tunnel expansion following anterior cruciate ligament reconstruction: a comparison of hamstring and patellar tendon autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234–238. 10. Fauno P, Kaalund S. Tunnel widening after hamstring anterior cruciate ligament reconstruction is influenced by the type of graft fixation used: a prospective randomized study. Arthroscopy 2005;21:1337–1341. 11. Wolf EM. Semitendinosus and gracilis anterior cruciate ligament reconstruction using the TransFix technique. Tech Orthop 1998;13:329–336. 12. Harilainen MD, Sandelin J, Jansson K. Cross-pin fixation versus metal interference screw in ACL with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33. 13. McKeon BP, Gordon M, Deconciliis G, et al. The “safe zone” for femoral cross-pin fixation. An anatomical study. Am J Knee Surg; In Press. 14. McKeon BP, Heming JD, Langeland R, et al. The Krackow stitch: a biomechanical evaluation of changing the number of locking loops versus the number of sutures. Arthroscopy 2006;22:33–37. 15. Hantes ME, Dailiana Z, Zachos VC, et al. Anterior cruciate ligament reconstruction using the Bio-TransFix femoral fixation device and anteromedial portal technique. Knee Surg Sports Traumatol Arthrosc 2006;14:497–501. 16. Ishibashi Y, Rudy T, Livesay G, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system. Arthroscopy 1997;13:177–182.

Stryker Biosteon Cross-Pin Femoral Fixation for Soft-Tissue Anterior Cruciate Ligament Reconstruction INTRODUCTION In the past, soft-tissue anterior cruciate ligament (ACL) reconstructions have had several distinct disadvantages, despite the fact that multiplestrand hamstring grafts have been shown to have higher strength, stiffness, and cross-sectional area compared with patellar tendon grafts.1–3 Soft-tissue healing into bone tunnels is considerably slower than bone–bone healing (about three times slower4) and probably takes as long as 10 to 12 months for mature healing with Sharpey’s fibers to occur.5 Fixation points distant from the intraarticular portion of the graft have resulted in more motion of the graft within the tunnel, creating additional problems with graft–tunnel healing, as well as contributing to tunnel widening. Fixation has traditionally been the weak link in soft-tissue reconstructions, with constructs that both were weak initially and failed to withstand extended cyclical loading, which would be necessary to allow the additional time for soft-tissue– bone healing to occur. However, the morbidity of hamstring harvest seems to offer several significant advantages over that of patellar tendon grafts, including issues such as extensor weakness, anterior knee pain, patellar entrapment/ patella baja, and patella fracture. In short, the conventional wisdom was that patellar tendon grafts provided tighter knees with more secondary problems, whereas hamstring grafts resulted in increased laxity but less morbidity. The challenge of the past several years, therefore, has been to eliminate these

disadvantages as much as possible while maximizing the inherent advantages of soft-tissue ACL reconstruction. To that end, the Stryker Biosteon Femoral Cross-Pin System was designed with the following goals in mind:

37 CHAPTER

John C. Anderson Lonnie E. Paulos

1 Make it possible for the surgeon to shorten the femoral tunnel and bring the fixation point as close to the joint as possible, with the only limitation being bone quality and healing surfaces. 2 Provide rigid initial fixation that, in addition to having excellent strength at time zero, is also resistant to cycling, which would allow aggressive early rehabilitation. 3 Use a bioabsorbable material (enhanced to form bone) that will be readily incorporated by the body, retain strength for an adequate period of time, obviate the need for secondary procedures such as hardware removal, and facilitate revision surgery. Bioabsorbable materials also have the advantage of a lack of stress shielding compared with permanent implants.6,7 4 Provide a press-fit of the graft against the tunnel walls in addition to simply providing a pin with high load to failure (LTF) and pullout strength. More specifically, the goals would be increasing bone/soft-tissue contact area and contact pressure. 5 Allow anatomical (far posterior and lateral) graft placement, without compromise of fixation if the posterior wall is blown out.

267

Anterior Cruciate Ligament Reconstruction 6 Minimize damage to the graft as the implant is placed, in contrast to interference screw fixation. Successful ACL reconstruction using hamstring autograft requires stable initial graft fixation and, ultimately, graft–bone healing. Hamstring reconstruction using femoral cross-pin fixation has been shown to have excellent initial mechanical properties, including pullout strength.8,9 Whereas femoral interference screw fixation requires a slightly more anterior femoral tunnel that fails to reproduce native ACL anatomy exactly, cross-pin fixation allows for placement of the femoral tunnel in the far posterolateral notch, a more anatomical position that provides improved biomechanical properties. The Stryker Biosteon Femoral Cross-Pin technique described in this chapter has the mechanical advantage of achieving “press-fit” graft fixation close to the knee joint and therefore increased graft stiffness,10 as well as the biological advantage of not interfering with bony and soft-tissue–bone healing.

SURGICAL TECHNIQUE

WHY HYDROXYAPATITE? Hydroxyapatite has been widely investigated and used extensively as a bone graft substitute, and it has a track record of being safe and effective (references). The basic advantages of this application are: (1) pH buffering, (2) the implant material is replaced by bone, and (3) the modulus of elasticity is matched to bone (i.e., no stress shielding). In terms of pH, hydroxyapatite particles provide a buffering effect as the poly-L-lactic acid (PLLA) is degraded into lactic acid.11 The material is therefore not subject to autocatalytic degradation, which can result in formation of a sterile abscess. This also serves to create a more controlled degradation process, with more gradual loss of strength over an extended period of time compared with PLLA alone (Fig. 37-1). Dynamics of healing and strength retention profile of Biosteon® in comparison with PLLA in-vivo

Strength Retention %

100 90 80 70 60 50 40 30 20 10 0

Ideal Biological Healing Curve5 Poly Lactide Biosteon® 0

4

8 12 Time (weeks in vivo)

16

20

FIG. 37-1 Rate of degradation of Biosteon versus poly-L-lactic acid (PLLA) alone.

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Osteoblasts bind preferentially to the surface of Biosteon as compared with poly-L-lactic acid (PLLA) alone (Fig. 37-2). Hydroxyapatite is remodeled through cellmediated processes. Osteoblasts cultured on the surface of hydroxyapatite express genes associated with the production of osteocalcin and CBFA-1 (proteins involved in the process of osteogenesis). With hydroxyapatite, a direct biological bond is achieved through osteoconduction, with less of a fibrotic reaction. It is therefore less likely that fixation will be compromised by an interface consisting of fibrous tissue that encapsulates the implant (Fig. 37-3). As far as modulus of elasticity, Biosteon lies somewhere between the moduli of cortical and cancellous bone (Fig. 37-4), thereby greatly decreasing the risk of stress shielding, even prior to the breakdown of the implant material. In short, hydroxyapatite enhances the healing properties of PLLA while minimizing many of the drawbacks.

Initial Arthroscopy The patient receives intravenous antibiotics preoperatively. After induction of anesthesia, an exam under anesthesia is performed. The patient is then positioned supine with the operative leg in an arthroscopic leg holder and a tourniquet on the upper thigh. The knee is routinely injected with 30 mL of 0.25% bupivacaine (Marcaine) at the beginning of the case for purposes of preemptive analgesia. Diagnostic arthroscopy is performed, and any chondral or meniscal procedures are performed at this time. A minimal lateral wall notchplasty is performed for visualization purposes only; we rely upon accurate graft placement rather than an aggressive notchplasty to avoid impingement, as a débrided notch has been shown to regrow.12 In addition, an overzealous notchplasty may have deleterious effects on the ACL reconstruction by altering the femoral attachment site and increasing graft forces, resulting in loosening.13,14 Furthermore, removal of too much of the lateral condyle can change joint contact forces significantly.15 Preservation of the integrity of the fat pad is also of paramount importance because it reduces the risk of patellar entrapment during recovery and rehabilitation.16,17 Placement of the anterolateral portal a few millimeters superior to the conventional position serves to avoid the fat pad and will improve visualization without the need to débride or excise any of the fat pad. We typically place the anterolateral portal at the level of the distal pole of the patella (if patella alta is not present), immediately lateral to the patellar tendon.

Stryker Biosteon Cross-Pin Femoral Fixation for Soft-Tissue Anterior Cruciate Ligament Reconstruction

37

Area Coverage % 0

10

20

30

40

50

60

70

80

3 days Culture Period 14 days

Biosteon

PLLA

FIG. 37-2 Osteoconductive properties of hydroxyapatite. PLLA, Poly-L-lactic acid.

In vivo 6 months post-implantation PLLA screw

Titanium screw

Biosteon screw

New bone has formed in all the contours of the screw threads

A fibrous layer is clearly visible between the screw and the bone FIG. 37-3 Biosteon encourages bony rather than fibrous healing. PLLA, Poly-L-lactic acid.

Modulus/MPa 0

50,000

100,000

150,000

200,000

250,000

Cancellous7 Biosteon Cortical 8 Titanium Stainless Steel FIG. 37-4 Modulus of elasticity of Biosteon is closely matched to bone.

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Graft Harvest and Preparation Graft harvest is discussed in detail in other chapters, but a few points are worth mentioning. With hamstring grafts, it is important to pull the graft into the tendon stripper, rather than push the stripper up the thigh, to avoid amputating the graft prematurely. We harvest the semitendinosus tendon first, and if the tendon is at least 28 cm long, it can be quadrupled and used alone as the ACL graft. If the tendon is less than 28 cm, the gracilis is harvested as well. Number 5 permanent sutures are whipstitched at the free tendon end(s), leaving 55 mm of graft centrally and ensuring that sutures will occupy the entire length of the tibial tunnel. The tendons (with sutures in place) are then placed under 30 pounds of tension for 20 to 30 minutes.

Tibial Tunnel Location and Preparation The senior author’s current preference for tibial tunnel placement is to use the Howell guide, which effectively prevents placing the tunnel where the ACL would impinge on the notch in full extension or the posterior cruciate ligament (PCL) in flexion. The diameter of the tibial tunnel is determined by passing the bundle of harvested tendons through various sizers and then choosing a reamer 0.5 mm smaller than the smallest sizer through which the graft will pass. Sizing in this way provides a tight fit and secure fixation in the tunnel and limits micromotion and secondary tunnel widening. We also like to use a trephine or coring reamer rather than a traditional reamer, which allows the harvest of cancellous bone for later use in grafting the tibial tunnel between the strands of tendon graft, prior to interference screw placement.

Femoral Tunnel Location and Preparation The optimum location of the femoral tunnel is in the posteromedial footprint of the native ACL, 1 to 2 mm anterior to the back wall and about 45 degrees of external rotation from vertical (i.e., approximately 10 o’clock on a right knee). The 2.4-mm forked femoral guide pin is passed through the tibial tunnel (or the anteromedial portal) with the knee flexed at least 90 degrees. The tip is placed no more than 2 mm anterior to the posterior femoral cortex in the appropriate position. An offset guide, such as the Stryker Femoral Aimer, may be used if desired. If such a guide is used, it is necessary to flex the knee beyond 90 degrees to allow the guide to sit flush against the bone of the back wall of the notch. It is important to note that when a Biosteon cross-pin is used for femoral fixation, the posterior femoral cortex can be breached without compromising fixation. Therefore, there is no reason not to place the femoral tunnel as far posteriorly as desired. 270

However, if the posterior wall is compromised, either intentionally or unintentionally, there are two important considerations. First, it is desirable to orient the cross-pin parallel to the transepicondylar axis or perhaps angled slightly anteriorly so as to ensure adequate bony support posterior to the cross-pin. Second, the surgeon should consider reaming the femoral tunnel deeper, especially if the tunnel was at all short to begin with, because this will effectively place the cross-pin more anteriorly, thereby increasing the thickness of bone posteriorly (although at the expense of graft length, as discussed earlier). The femoral pin is advanced into the femur, out the anterolateral femoral cortex, and then through the skin of the anterolateral distal thigh. The femoral tunnel is then reamed to a depth of 20 to 30 mm, depending on the surgeon’s preference, using the appropriate diameter of reamer based on graft size. It may be preferable to drill a shorter tunnel, both to bring the fixation point closer to the joint and to leave more graft length distally to allow more flexibility in tibial fixation. Drilling a shorter femoral tunnel will also make it more likely that a quadrupled semitendinosus tendon will provide adequate length. We then broach the anterolateral femoral cortex using a 4.5-mm cannulated drill over the guide pin, although this step is optional. This allows easier passing of heavy sutures or suture tape (our preference) later in the case as the graft is passed and seated. However, the tip of the forked femoral guide pin does have a larger diameter than the rest of the pin, which accomplishes some of the same effect, although to a lesser extent. Once this step is completed, the 2.4-mm forked femoral guide pin in retracted into the femoral tunnel under direct arthroscopic visualization so that it sits just above the level of the wider portion of the tunnel (just inside the 4.5-mm portion of the tunnel). This is done to prevent interference with the transverse drill guide. The femoral pin is then secured at the skin proximally to prevent accidental pullout.

Femoral Fixation A transverse femoral index guide equal in diameter to the femoral tunnel (or slightly smaller) is selected, and the transverse drill guide is assembled. The transverse drill guide is inserted through the tibial tunnel and into the femoral tunnel to the desired depth. This step may also be accomplished through the anteromedial portal with the knee hyperflexed (especially if the double-bundle technique is employed). As with any guide pin system, it is important not to change the degree of knee flexion once the femoral guide pin is in place. The same principle applies when the transverse drill guide is in the femoral tunnel; otherwise, tunnel or instrument damage may occur. It should be noted that the transverse drill guide places the Biosteon cross-pin

Stryker Biosteon Cross-Pin Femoral Fixation for Soft-Tissue Anterior Cruciate Ligament Reconstruction 8 mm inferior to the tip of the transverse femoral index guide; this offset is built into the guide system and requires no adjustments on the part of the surgeon. For example, a 25-mm femoral tunnel will place the center of the Biosteon cross-pin 17 mm from the aperture of the femoral tunnel, through the loop of hamstring graft. The transverse drill guide is aimed parallel or slightly anterior to the transcondylar axis to protect the neurovascular structures in both the posterior and medial aspects of the knee and to ensure sufficient posterior bone support for the Biosteon cross-pin, as detailed earlier. A stab incision is created laterally, and the transverse guide bullet is advanced gently to bone. It is important to avoid forcing the bullet into position against the lateral femoral cortex, as this can torque the guide and lead to significant problems in later steps due to a malaligned guide pin. If in doubt, simply ensure that the bullet slides freely in the drill guide, without regard for whether or not it is seated on bone, because the alignment of the guide is the critical factor. The bullet can be advanced down to bone after the guide pin is in place for measuring purposes (see later discussion). Once the guide bullet is in place, the 2.7-mm transverse threaded guide pin is advanced through the bullet from lateral to medial until it exits the skin medially (Fig. 37-5). Use gentle pressure rather than forcing the drill

FIG. 37-5 With the transverse drill guide in position, the transverse guide bullet is advanced into position, taking care not to alter the trajectory by forcing the bullet against soft tissues or the femoral cortex. The 2.7-mm transverse threaded guide pin is then driven across the femur and oriented properly, as described in the text.

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so to avoid misdirecting the pin. The guide pin should emerge at or slightly posterior to the medial epicondyle. The transverse guide bullet is calibrated, allowing a measurement to determine the correct length of the Biosteon cross-pin; this number is read directly from the outside of the transverse drill guide, without any conversion or addition/ subtraction. This measurement system is designed to determine the distance from the lateral femoral cortex to 10 mm beyond the medial wall of the femoral tunnel (assuming a tunnel diameter of 10 mm), thus providing ample medial bony support for the cross-pin. In practical terms, the authors use a 50-mm cross pin in all but the smallest knees (a 40-mm pin is also available). Once the transverse threaded guide pin is in place, the transverse drill guide is removed. Direct arthroscopic visualization into the femoral tunnel (through the tibial tunnel) allows the surgeon to confirm that the transverse guide pin passes through the center of the femoral tunnel (Fig. 37-6). With the arthroscope still in the femoral tunnel, the 5-mm fluted reamer is advanced over the transverse guide pin into the femoral tunnel. In most patients the drill is advanced to a depth of approximately 10 mm less than the length of the Stryker cross-pin being used. Under direct visualization, this usually corresponds to drilling just a few millimeters into the lateral wall of the femoral tunnel. In patients with less dense bone, it may only be necessary to perforate the lateral femoral cortex. The Flexwire is then secured to the lateral end of the 2.7-mm transverse threaded guide pin already in position in the femur. The threaded guide pin is then pulled out of the femur medially, pulling the Flexwire into the femur and

FIG. 37-6 The transverse drill guide assembly ensures that the cross-pin will bisect the femoral tunnel; this is confirmed arthroscopically.

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Anterior Cruciate Ligament Reconstruction across the femoral tunnel. The threaded guide pin is detached medially, and the Flexwire is secured on both sides of the knee. With the arthroscope again looking into the femoral tunnel for direct visualization, the surgeon advances the 2.4-mm forked femoral guide pin back down the femoral tunnel toward the scope and captures the Flexwire with the forked end of the pin. (This step is made easier if the femur is reamed to 4.5 mm all the way out of the anterolateral cortex, as described earlier, which allows the surgeon to have some control of the direction of the forked pin while attempting to capture the Flexwire.) The pin and wire are then advanced by hand into the joint and out through the tibial tunnel (Fig. 37-7). (We opt here to detach the camera from the arthroscopic sleeve, retracting the camera and advancing the pin and wire into the sleeve under direct vision. This prevents twisting and soft-tissue impingement as the pin, wire, and sleeve are retracted together through the joint and out the tibial tunnel.) It is critically important to keep the Flexwire from twisting at all times, especially once is it out of the tibial tunnel distally. Twisting the Flexwire can be disastrous if unrecognized, causing at best abrasion and weakening of the graft as it is pulled into the tunnel and the Flexwire untwists, and at worst breakage of the Flexwire and/or amputation of the graft if the Flexwire is not untwisted prior to impacting the cross-pin into position.

FIG. 37-7 The forked femoral guide pin is used to capture the Flexwire in the femoral tunnel and deliver it at the distal tibia.

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With the Flexwire and the forked femoral guide pin protruding from the distal end of the tibial tunnel, the hamstring (or other soft tissue) graft is looped over the Flexwire, again taking care not to twist either the graft or the wire. Next, a loop of polyester tape (our preference) or #5 suture, which has previously been passed through the loop of hamstring graft, is threaded through the eyelet at the end of the forked femoral guide pin (Fig. 37-8). The forked femoral guide pin is then pulled proximally through the tibial and femoral tunnels and out the skin of the anterolateral thigh, delivering the polyester tape or suture to the surgical assistant. The assistant applies tension to the tape, and the graft is advanced into the femoral tunnel to the maximum depth, while at the same time, even tension is applied to both ends of the Flexwire to pull it back up into the femoral tunnel to form a straight line again. These two actions are performed simultaneously, but the suture or tape must perform the work of pulling the graft into the femoral tunnel. If tension on the Flexwire is used to seat the graft, abrasion of the graft and/or tunnel may occur. Once the ACL graft is in place, the Flexwire should glide easily medially and laterally with

FIG. 37-8 The graft is then looped over the Flexwire and advanced into the joint using the suture tape, which is passed through the forked femoral guide pin and brought out through the skin proximally.

Stryker Biosteon Cross-Pin Femoral Fixation for Soft-Tissue Anterior Cruciate Ligament Reconstruction minimal resistance; this confirms that there is free passage through the transcondylar tunnel and the loop of graft. However, this maneuver should only be performed once so as to avoid abrasion of the graft. After graft position is confirmed, one end of the tape or suture is cut and the other end is pulled out of the thigh. This is done to avoid trapping the tape or suture when the stepped insertion pin and subsequently the cross-pin itself are passed, and also to facilitate their passage. The stepped insertion pin is then attached to the Flexwire laterally and advanced into the femur and through the loop of graft in the femoral tunnel, leaving enough of the pin protruding laterally to guide the cross-pin into position. The Flexwire can then be detached from the pin medially, although this step is not necessary. The surgeon can test graft position by tensioning the distal sutures, confirming that the graft is looped over the rigid guidewire in the femoral tunnel. The Biosteon cross-pin is then passed over the lateral end of the stepped insertion pin and advanced by hand until the cross-pin is seated against the shoulder of the stepped insertion pin. The cannulated tamp is placed against the cross-pin and used to advance it over the insertion pin (and thereby under the graft) with a mallet until it is seated (Fig. 37-9). The cross-pin is fully seated into the lateral condyle when the shoulder of the tamp is flush with the lateral femoral cortex. The stepped insertion pin is then removed medially.

Tibial Fixation This topic is likewise covered in detail elsewhere, but we would again like to mention a few points. Once femoral fixation is complete, the knee is cycled through a full arc of

37

motion 20 times while steady tension is maintained on the individual graft strands distally. This should help to eliminate graft kinking and creep and thus increase graft rigidity. In addition, this helps set the sutures in the distal graft strands and eliminate any areas of laxity, which again should result in more predictable and reproducible tensioning. The senior author’s current preference for tibial fixation is a Mitek IntraFix sheath (bioabsorbable) with a Biosteon interference screw and an Interlock bioabsorbable pin across the sheath/screw. These implants should never be prominent or symptomatic, thereby obviating the need for implant removal. Again, we prefer to bone graft the tibial tunnel prior to distal fixation. When using the previously mentioned implants, hardware removal should never be necessary for symptomatic reasons.

POSTOPERATIVE CARE A brace locked in full extension is applied in the operating room. A physical therapist instructs the patient in the recovery room in appropriate exercises such as quad sets and straight leg raises to maintain quadriceps tone. The patient is typically non–weight bearing and immobilized for the first postoperative week for comfort. The brace is unlocked at 7 to 10 days postoperatively, and range of motion exercises are begun according to our customized protocols. Because of the stability of the fixation with the Stryker Biosteon cross-pin and tibial fixation described earlier, the patient may advance to full weight bearing by approximately postoperative week 3. Patients may swim in the second month, bike in the third, run straight ahead in the fifth, and return to sport at 7 to 8 months.

FIG. 37-9 The Stryker Biosteon cross-pin is inserted over the guide pin.

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Anterior Cruciate Ligament Reconstruction Our rehabilitation program is fairly aggressive for a soft-tissue graft, due to the excellent initial stability provided by the fixation. However, one should keep in mind that soft-tissue–bone healing still takes considerably longer than bone–bone healing.

BIOMECHANICAL PERFORMANCE OF STRYKER BIOSTEON CROSS-PIN The Biosteon cross-pin was tested for pullout strength and mode of failure at an outside laboratory in a porcine model. In the porcine model, the average maximum load was 1217.8N, whereas the average yield load was 1052.9N. This compared favorably with the Arthrex Bio-TransFix (PLA) pin, which had significantly lower values in both categories. Displacement at yield load averaged 11.56 mm for the Stryker implant, which was similar to the Arthrex implant. (Please see Fig. 37-10 for full details.) Of note is the fact that a higher percentage of the Arthrex ACL reconstructions failed via graft failure at the proximal end, which could be attributed to the fact that the Arthrex implant has a 5-mm diameter compared with the 6-mm diameter of the Stryker implant, which should create less of a stress riser on the graft as it loops over the implant. In keeping with this trend, a greater proportion of the Stryker implants actually broke, as opposed to the grafts failing, although again this was at a higher load.18

RESULTS The senior author performed 82 ACL reconstructions using the Stryker cross-pin and reported early results (2- to 3.3-year

follow-up). Of the 82 patients, 30 had acute injuries and 52 had chronic ACL deficiency. The ACL was the only ligament injured in 53 patients, whereas 20 patients also had a medial collateral ligament (MCL) injury, six patients had concomitant patella dislocation, and three patients had lateral ligamentous injury as well. The average age was 28 years, and 47 were male, whereas 35 were female. Patients followed the postoperative protocol described earlier. Complications included deep infection (1), superficial infection (2), deep venous thrombosis (1), loss of motion requiring manipulation (2), and saphenous nerve paresthesias (1). In terms of graft stability and survival, one patient had traumatic graft rupture, two patients had a positive pivot shift, and eight patients had a positive pivot glide. KT-1000 measurements showed an average translation with 20 pounds of force of 1.3 mm, with an average maximum translation of 1.7 mm. Eighty-four percent of patients had a maximum KT-1000 translation of less than 3 mm, 16% had 4 to 5 mm, and 5% had more than 5 mm. Range of motion results included an average extension loss of 0 degrees (range –5 to 7 degrees) and an average flexion loss of 8.2 degrees (range 0 to 10 degrees).

CONCLUSIONS The Stryker Biosteon cross-pin achieves many of the previously unattainable goals in soft-tissue ACL fixation on the femoral side. Rigid initial fixation, which is resistant to cycling, is obtained. The fixation is placed relatively close to the intraarticular portion of the graft, thereby effectively shortening graft length and minimizing the potential for creep and tunnel widening. A good press-fit is obtained,

1400 Stryker Arthrex

1200 1000

N

800 600 400 200 0 Maximum load

Cross-pin brand

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Yield load

Max load (N)

Displ. @ max load (mm)

Yield load (N)

Displ. @ yield load (mm)

Stryker

Mean SD

1217.8 234.4

15.37 2.94

1052.9 296.7

11.56 2.73

Arthrex

Mean SD

934.5 177.8

11.53 2.43

890.6 212.8

10.27 2.49

FIG. 37-10 Data from testing in a porcine model.

Stryker Biosteon Cross-Pin Femoral Fixation for Soft-Tissue Anterior Cruciate Ligament Reconstruction

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TABLE 37-1 Potential Pitfalls and Solutions Problem

Solution

Posterior wall disruption

No compromise in fixation, as long as cross-pin is oriented properly (parallel to transepicondylar axis or angled slightly anteriorly). Consider making the femoral tunnel slightly deeper to ensure adequate bone support posterior to the cross-pin.

Difficulty capturing Flexwire with forked femoral

As part of femoral tunnel preparation, overdrill with a 4.5 reamer all the way through the

guide pin

femur and out the anterolateral cortex, which will allow some control of the direction of the forked guide pin while trying to capture the Flexwire.

Twisting of Flexwire (can cause breakage of Flexwire

Prevent this by bringing the Flexwire down through the tibial tunnel under direct

and/or amputation of graft)

visualization with the arthroscope. After the graft is pulled into the femoral tunnel, confirm that no twist is present by checking that the Flexwire slides back and forth easily across the femur (once only to avoid graft abrasion).

Damage to forked femoral guide pin (by either the

Ensure the pin is withdrawn far enough proximally so that the tip is completely out of the

transverse threaded guide pin or the step drill)

femoral tunnel but still in the femur (under direct arthroscopic visualization through the tibial tunnel).

Difficulty passing stepped insertion pin and/or cross-pin

When drilling with the step drill, make sure to penetrate all the way into the femoral tunnel,

(implant)

and then touch the tip of the drill bit against the far (medial) side of the tunnel to create a small divot to assist the stepped insertion pin, and later the actual implant, in finding the path. If the stepped insertion still will not pass, you may tap gently with a mallet while maintaining tension on the Flexwire from the medial side.

which should serve to promote graft–bone healing. A bioabsorbable implant material is used, which promotes bony healing in addition to simplifying revision surgery. Finally, anatomical graft placement is possible, and fixation is not compromised by posterior wall blowout. We believe that these factors represent a significant advancement in soft-tissue ACL reconstruction, bringing it closer to the gold standard of bone–patellar tendon–bone reconstruction in terms of stability and healing while maintaining the advantages of less morbidity (see Table 37-1 for pitfalls and solutions).

References 1. Brahmabhatt V, Smolinski R, McGlowan J, et al. Double-stranded hamstring tendons for anterior cruciate ligament reconstruction. Am J Knee Surg 1999;12:141–145. 2. Hamner DL, Brown CH, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg 1999;81A:549–557. 3. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee ligament repairs and reconstructions. J Bone Joint Surg 1984;66A:344–352. 4. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 5. Robert H, Es-Sayeh J, Heymann D, et al. Hamstring insertion site healing after anterior cruciate ligament reconstruction in patients with symptomatic hardware or repeat rupture: a histologic study in 12 patients. Arthroscopy 2003;19:948–954.

6. Ciccone WJ, Motz C, Bentley C, et al. Bioabsorbable implants in orthopaedics: new developments and clinical applications. J Am Assoc Orthop Surg 2001;9:280–288. 7. Martinek V, Lattermann C, Watkins SC, et al. The fate of the poly-L-lactic acid interference screw after anterior cruciate ligament reconstruction. Arthroscopy 2001;17:73–76. 8. Kousa P, Järvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 9. Paulos LE, Ellis B. ACL fixation pullout studies. Salt Lake City, 2002, Orthopedic Biomechanics Institute. 10. Scheffler SU, Südkamp NR, Göckenjan A, et al. Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: the impact of fixation level and method under cyclic loading. Arthroscopy 2003;18:304–315. 11. Agrawal CM, Fan MM, Zhu C, et al. A new technique to control the pH in the vicinity of biodegradable implants. Presented at the Fifth World Biomaterials Congress, Montreal, Canada, April, 1996. 12. LaPrade RF, Terry GC, Montgomery RD, et al. The effects of aggressive notchplasty on the normal knee in dogs. Am J Sports Med 1998;26:193–200. 13. Hame SL, Markolf KL, Hunter DM, et al. Effects of notchplasty and femoral tunnel position on excursion patterns of an anterior cruciate ligament graft. Arthroscopy 2003;19:340–345. 14. Markolf KL, Hame SL, Hunter DM, et al. Biomechanical effects of notchplasty in anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:83–89. 15. Lowe WR, Noble P. Unpublished data. 16. Paulos LE, Rosenberg TD, Drawbert J, et al. Infrapatellar contracture syndrome: an unrecognized cause of knee stiffness with patella entrapment and patella infera. Am J Sports Med 1987;15:331–341. 17. Paulos LE, Wnorowoski DC, Greenwald AE. Infrapatellar contracture syndrome: diagnosis, treatment, and long-term follow-up. Am J Sports Med 1994;22:440–449.

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Anterior Cruciate Ligament Reconstruction 18. Stryker Endoscopy data 2002. Study performed by Frontier Biomedical, Logan, UT.

Suggested Readings Böstman O. Intense granulomatous inflammatory lesions associated with absorbable internal fixation devices made of polyglycolide in ankle fracture. Clin Orthop 1992;278:191–199. Brand JC, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. Ciarelli MJ, Goldstein SA, Kuhn JL, et al. Evaluation of orthogonal mechanical properties and density of human trabecular bone from major

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metaphyseal regions with materials testing and computed tomography. J Orthop Res 1991;9:674–682. Frokjaer J, Moller BN. Biodegradable fixation of ankle fractures. Complications in a prospective study of 25 cases. Acta Orthop Scand 1992;63:434–436. Gefen A. Optimising the biomechanical compatibility of orthopaedic screws for fracture fixation. Engineering Physics 2002;23:337–347. Kehoe NJS, Hackney RG, Barton NJ. Incidence of osteoarthritis in the scapho-trapezial joint after Herbert screw fixation of the scaphoid. J Hand Surg 2003;28B:496–499. Kousa P, Järvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. Lotz JC, Gerhart TN, Hayes WC. Mechanical properties of metaphyseal bone in the proximal femur. J Biomech 1991;24:317–329.

Anterior Cruciate Ligament Reconstruction Utilizing the Rigidfix for Femoral-Sided Fixation BACKGROUND Graft selection for anterior cruciate ligament (ACL) reconstruction has been debated in the literature.1 Historically, the debate has been regarding the use of soft tissue grafts secondary to increased laxity as compared with patellar tendon autografts.2 The point of concern occurred at the site of graft fixation with soft tissue grafts, and the issues were “suspensory” fixation and creep with cyclical loading. Improved fixation techniques have largely eliminated the historical differences in laxity comparing quadrupled hamstring tendon with bone–patellar tendon– bone (BPTB) autografts.3 It has been well documented in recent literature that the two graft types have similar success rates.4–6 Some potential advantages of soft tissue grafts include decreased kneeling pain, decreased patellar tendonitis, lower risk of postoperative patella fracture, and improved cosmesis with a smaller incision for harvest.1 The patellar tendon graft, with bone plugs on each end, has classically been fixed with a metal interference screw in the tibia and femur with near-aperture fixation. This fixation was sufficiently rigid to prevent significant graft slippage or creep. The patellar tendon graft became the gold standard by which all other grafts and graft fixation systems were compared.1 Despite the increased laxity with hamstring tendon reconstructions, this technique gained popularity as patients complained of significant anterior knee and kneeling pain with patellar tendon

autografts. The potential for patellar fracture also exists. Hamstring tendon autografts have less morbidity, although they do demonstrate some permanent hamstring weakness at high flexion angles.7 The clinical significance of this weakness remains unclear. A quadrupled hamstring tendon graft has two significant biomechanical advantages. First, quadrupled hamstring grafts have a larger crosssectional area when compared with patellar tendon grafts.7 The larger cross-sectional area results in more collagen and thus a stronger graft. The ultimate tensile strength of a quadrupled hamstring autograft is 4140N with a stiffness of 807 N/mm. This is compared to the patellar graft at 2977N and 455 N/mm, respectively. The native ACL has been tested at 2160N and 242 N/mm, respectively.1 Second, hamstring tendon grafts require smaller bone tunnels than do grafts with bone plugs. These grafts heal circumferentially to the tunnel wall if the interference screw is eliminated. These advantages fueled the search for better soft tissue graft fixation devices. The historical poor performance of soft tissue grafts cannot be compared with today’s graft fixation. Initial studies compared doubled hamstring tendons to patellar tendons. A quadrupled soft tissue graft is the optimal choice when hamstring tendons are used. Studies of soft tissue graft fixation preceded the use of transfixion devices. Kousa et al8 tested the pullout strength of the soft tissue fixation devices that are currently most used for hamstring grafts. On the femoral side, the Bone Mulch

38 CHAPTER

John Richmond Michael Kuhn

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Anterior Cruciate Ligament Reconstruction Screw (Arthotek, Warsaw, IN) (1112N), Endobutton-CL (Smith & Nephew, Endoscopy Division, Andover, MA) (1086N), and Rigidfix (Depuy Mitek, Westwood, MA) (868N) systems had the best fixation for soft tissue grafts.8 These were significantly stronger than patellar tendons fixed with an endoscopic interference screw (588N). On the tibial side, the fixation is much more secure. The IntraFix (Depuy Mitek) (1332N) and WasherLoc (Arthrotek) (975N) both had higher pullout strengths than a patellar tendon bone plug fixed with a metal interference screw (758N, 9-  30-mm screw). Interference screws for soft tissue grafts are weaker, with pullout strengths from 201N to 665N depending on the system.8 The improved fixation systems for hamstring tendons, combined with strength and stiffness superior to the native ACL, make this an attractive graft option. One must challenge any concept of a BPTB autograft as the gold standard. Patient factors and desires and the surgeon’s preference should dictate which graft is chosen. Surgeons completing ACL reconstructions should be well versed in both techniques. Allograft reconstruction offers an additional soft tissue option. For those surgeons or patients desiring an allograft source, the tibialis anterior tendon has an ultimate tensile strength of 4122N and is an attractive alternative.9 We also use the technique described here when an allograft tibialis is selected.

tendons. This is palpable in most patients, but when not palpable, the middle of the tibial tubercle can be used to estimate its location. An oblique, skin-fold incision is used for graft harvest. This incision parallels the gracilis tendon. This incision is approximately 3 cm in length and is centered over the anterior border of the medial collateral ligament (Fig. 38-1). This is generally 4 to 5 cm medial to the tibial tubercle. Both arthroscopic portals and the harvest incision are injected with 5 to 10 mL of 1% lidocaine with epinephrine for the hemostatic effect.10 After the skin incision is made and subcutaneous soft tissues mobilized, the intersection of the anterior border of the medial collateral and the superior border of the sartorius fascia is marked with electrocautery (Fig. 38-2). The main advantage of this starting point is that it allows a relatively horizontal femoral tunnel in the coronal plane when the femoral tunnel is drilled through the tibial tunnel. Vertical grafts in the coronal plane have been associated with increased anterior laxity and functional instability. In order to locate this landmark later in the procedure, the electrocautery is used to make a cruciform periosteal incision that exposes enough of the tibia for the tibial tunnel drill site.

SURGICAL TECHNIQUE Patients undergoing ACL reconstruction are treated in the outpatient surgical suite. General anesthesia is combined with the intraarticular injection of a local anesthetic containing epinephrine to obviate the need for a tourniquet. The leg holder is positioned in as proximal a position on the thigh as possible so as to allow more than 100 degrees of flexion during graft tunnel preparation and graft passage if necessary. A well-padded tourniquet is placed on the upper thigh. It is not routinely inflated during the procedure in order to minimize quadriceps inhibition postoperatively. An examination under anesthesia is performed prior to final positioning. The knee is initially prepped with povidone-iodine (Betadine) and injected with 60 mL of 1% lidocaine with epinephrine (1:100,000). The injection is performed laterally adjacent to the superior lateral portion of the patella. During the injection, a fluid wave should be visualized medially, which ensures that a fat pad injection has not occurred. The hemostatic effect would largely be lost with a fat pad injection. The knee is then prepped and draped with standard arthroscopy drapes. Surgical landmarks are identified and marked on the skin, including the superior border of the pes anserine 278

FIG. 38-1 Preparing the skin incision for graft harvest. An oblique incision allows for easy harvest visualization, tunnel preparation, and a good cosmetic result.

Anterior Cruciate Ligament Reconstruction Utilizing the Rigidfix for Femoral-Sided Fixation

FIG. 38-2 Cruciform periosteal incision marking the site of tibial tunnel entry point.

The hamstring tendons are harvested after identifying the gracilis and semitendinosus tendons. It is our preference to used a closed loop tendon stripper to remove the tendons after freeing all palpable slips to the gastrocnemius and dissecting the tendon off the tibia, including Sharpey fibers. Once the tendons are harvested, they are passed to the back table for preparation. The gracilis and semitendinosus tendons are looped on a suture, creating a four-bundled graft (Fig. 38-3). The free ends of the tendons are sutured with #2 Orthocord (Depuy Mitek) in Krackow-type suture configuration. This is performed in the event that secondary fixation is desired in the tibia. Graft length is generally not an issue, but a minimum graft length of 10 cm, once quadrupled, ensures adequate soft tissue for fixation and ingrowth within the tibia and femur. The proximal end is sutured together with #2 Orthocord for a distance of 3 cm. Each individual graft strand is incorporated to ensure the creation of a single proximal mass. This is helpful to

FIG. 38-3 Graft preparation for Rigidfix. The proximal segment is sutured between strands to ensure capture by the implant.

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facilitate capture of the graft strands with the Rigidfix pins. Once suturing is complete, the graft is sized using a closed graft-sizing block, with 0.5-mm increments. The femoral side should fit snugly through the sizing block. The tibial side of the graft should freely pass through the sizing block. This, with the additional material of the Krackow sutures, often creates a 0.5 to 1.0 mm difference between the tibial and femoral tunnels. Finally, the graft is marked with a surgical pen 30 mm from the femoral tip of the graft. This allows intraarticular visualization of proper graft seating once it is passed. The graft should be kept under 12 to 15 pounds of tension on the back table until inserted. Simultaneously with graft preparation, the joint is examined and prepared. Two standard arthroscopic portals are established. A diagnostic arthroscopy is performed, treating any additional pathologic lesions that are encountered. The ACL stump and remnant tissue are removed, clearly identifying the femoral and tibial footprints. Once the soft tissue is removed from the notch, the need for a notchplasty is assessed. A minimal notchplasty is performed to identify the over-the-top position, widen the notch to accommodate the graft, and ensure that the graft will not impinge in full extension. Following completion of the notchplasty, the posterior compartment can be more easily visualized to ensure that no meniscal fragments or loose bodies remain. At this point, the ACL tibial guide is inserted. The ideal position for the guide is on the lateral downslope of the medial tibial spine, approximately 7 mm anterior to the posterior cruciate ligament (PCL).5 Once the tip is firmly seated, correct anteroposterior positioning can be confirmed. The tunnel should be directly medial to the midpoint between the insertions of the anterior and posterior horns of the lateral meniscus. The tip of the “bullet” portion of the guide is then placed on the previously marked junction of the anterior border of the medial collateral ligament and the superior border of the pes tendons on the anteromedial flare of the tibia. The tunnel length is noted and should be at least 30 mm in length. The angle on the ACL tibial guide should be set at approximately 55 degrees. Care is taken not to allow the tip of the bullet to move in a superior direction. If this occurs, an excessively flat and short tibial tunnel will be created. This may compromise both graft fixation and positioning of the femoral tunnel using the endoscopic transtibial approach. For this reason, the bullet is positioned within a few millimeters of the superior border of the sartorius fascia. A guide pin is drilled through the tibial tunnel guide. Once the pin emerges through the tibial footprint, the drill guide is removed and a hemostat is introduced through the medial portal and clamped to the tibial pin. The tibial tunnel is drilled to the predetermined size while maintaining 279

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pressure on the guide pin in a posterior direction using the hemostat. This prevents anterior migration of the intraarticular entry point as the drill penetrates into the joint anterior to the pin. The tunnel is then dilated 0.5 mm greater in diameter than the graft, allowing smooth graft passage. The posterior rim of the intraarticular tibial tunnel is inspected. Soft tissue flaps and any bony fragments are débrided to ensure a smooth surface for the graft in order to minimize abrasion at the tunnel entrance into the joint. The femoral over-the-top guide is selected. A 1-mm posterior wall is desired. Thus the offset guide should be 1 mm larger than half the diameter of the femoral end of the graft. The correct offset guide is placed through the tibial tunnel and positioned in the over-the-top position. The knee should be placed in 65 to 70 degrees of flexion for drilling of the femoral tunnel. If the guide is not easily positioned with the knee in this position, the knee may be slightly extended for guide placement and then gently flexed into desired position. Graft positioning in the femur plays a large role in successful reconstruction. The goal is to obtain as horizontal a graft as possible in the coronal plane. The femoral guide should be positioned as far from the 12-o’clock position as possible. The ideal positions to aim for are the 10:00 to 10:30 positions (on the clock face) for a right knee or 2:00 to 2:30 position for a left knee (Fig. 38-4). If this cannot be created through the tibial tunnel, the femoral guide can be placed through the medial portal and the tunnel drilled through this approach. If access through the medial portal

is required, the knee should be flexed to 110 degrees to ensure adequate bone for the femoral socket. Care should be taken to not allow the guide to slip anteriorly and to ensure the post remains in the over-the-top position. If anterior slippage were to occur, the femoral tunnel would be placed too anterior, drastically increasing the risk of graft failure. The Beath pin is drilled through the femoral guide through both cortices, but not through the skin of the lateral thigh. It should be palpable below the skin, allowing for easy retrieval if necessary. An acorn drill is used to create the femoral socket to a depth of 35 mm. This depth will allow 30 mm of the graft to be seated in the socket. In smaller and female patients, the cortex may be encountered prior to 35 mm. As long as the drill has penetrated 25 mm, we accept that as the depth because two Rigidfix pins can still be placed to engage the graft. Bone and soft tissue debris are removed from the femoral socket and notch. The appropriate-sized cannulated femoral rod is then attached to the cross-pin frame from the Rigidfix system and is inserted into the femoral tunnel over the Beath pin. Once it is fully seated, the Beath pin is removed (Fig. 385). If working through the tibial tunnel, the next step is to determine the exact position of joint flexion that provides the least resistance to rotation of the cross-pin guide frame. This step is crucial because knee flexion has often changed subtly since the femoral tunnel was drilled. Flexing and extending the knee a few degrees while rotating the guide frame permits the surgeon to determine which position of the knee allows the cross-pin guide frame to rotate freely and aligns the outrigger properly. This facilitates accurate position of the cross-pin sleeves and decreases the chance that one of the cross-pins will not penetrate the graft. If the guide is properly aligned, it should be nearly parallel to the floor.

FIG. 38-4 Identify the femoral point, and make a tunnel through the tibial tunnel when possible, reaching a depth of 30 mm. (Reproduced with permission by Depuy Mitek.)

FIG. 38-5 Position the Depuy Mitek Rigidfix femoral guide. Note that the arm of the guide is positioned lateral to the knee. (Reproduced with permission by Depuy Mitek.)

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FIG. 38-6 Introduce the guide, and then drill the two cannulated sleeves. (Reproduced with permission of Depuy Mitek.)

A cross-pin sleeve is then placed over the interlocking trocar. The distal hole in the cross-pin frame is drilled first (Fig. 38-6). The interlocking trocar is drilled until the crosspin sleeve is fully seated in its hole on the cross-pin guide frame. A small mallet is then used to gently tap the drill to disengage the interlocking trocar from the cross-pin sleeve. When it is disengaged, the user will see that the small interlocking pin on the trocar is no longer engaged with the sleeve. At this point, the trocar may be removed by spinning the drill. The observation of good fluid flow from the sleeve indicates central positioning of the pin in the tunnel. This process is repeated through the proximal slot on the outrigger. At this point, the cross-pin guide frame is disassembled and removed. The arthroscope is removed from the portal and is inserted through the tibial tunnel into the femoral socket to inspect the cross-pin holes. They should be centered in the tunnel. Passage of guide pins or nitinol wires through the sleeves should be preformed to identify their positions (Fig. 38-7). If only one is centered, we accept this as an acceptable fixation and insert both pins. If neither is correctly placed, graft fixation may not be adequate. At this point, an alternative type of femoral fixation should be employed. It is our preference to use a Milagro bioabsorbable screw, 1 mm over the diameter of the femoral socket. The Beath pin is now reinserted through the femoral tunnel and out through the skin on the lateral thigh. The suture on which the graft was looped is then retrieved and used to pass the graft. The cleft between the strands on the graft should be directed from the anterior to the posterior planes so that the Rigidfix pins will pierce all four arms of the quadrupled graft. The graft is then pulled so that the 30-mm pen mark just enters the femoral tunnel. The tunnel was ideally drilled to 35 mm because the tip of the drill is tapered 5 mm, resulting in 30 mm of

FIG. 38-7 Arthroscopic inspection of the location of the Rigidfix drill holes. (Reproduced with permission of Depuy Mitek.)

cylindrical tunnel and complete fill with a 30-mm graft. As previously mentioned, a 25-mm tunnel (20 mm of graft) can be accepted. The Rigidfix outrigger is designed with 11 mm of bone distal to the more caudal pin, allowing excellent fixation through a shorter socket. The first cross-pin is then inserted using the stepped pin insertion rod and tapped with a small mallet until it is fully seated. Increased resistance occurs as the pin is tapped across the graft. The proximal pin is inserted first. Once it is placed, distal tension of approximately 25 pounds is applied across the graft. This ensures that both pins will share the load. The distal pin is then inserted (Fig. 38-8). The cross-pin sleeves are then removed. It is crucial to cycle the knee to take up any

FIG. 38-8 Femoral fixation with two Rigidfix absorbable pins. The proximal pin is inserted first and the distal pin second. (Reproduced with permission of Depuy Mitek.)

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Anterior Cruciate Ligament Reconstruction creep that might occur. We routinely use 25 cycles from 0 to 90 degrees with 25 pounds of force using a tensioner. The tibial side is then fixed using the IntraFix sheath and screw device. The technique for this implant is covered in Chapter 47. Once the graft is fixed on the tibial side, it is again examined arthroscopically. It is placed through a range of motion and checked in full extension to ensure a lack of impingement. The graft is probed to visually check proper tension.

It is important to tension the graft at or near full extension in order to ensure that the knee does come to full extension in the operating room. The combination of these fixation devices, Rigidfix and IntraFix, results in a construct with very little creep under cyclical loading, and fixing the tibial side with 30 degrees of flexion may lead to overtensioning of the graft.

POSTSURGICAL CARE TROUBLESHOOTING Pitfalls may develop at any of several steps in the Rigidfix technique. The most common pitfall arises in placing the sleeves into the femur using the outrigger guide. If the trocar pin and sheath are drilled into the bone but will not advance to seat fully, be sure that you have removed the Beath pin because this prevents advancing the trocar through the guide. If the Beath pin has been removed and the sheath and trocar will not advance, it is likely that you have changed the angle of the joint enough to slightly deform the guide. Oftentimes the trocar tip will slide into the slot in the guide. Unfortunately, it may also slide off the guide, making the hole for the pin too eccentric to effectively capture the graft. If this occurs and the sleeve has good purchase in the femur, as you visualize the hole with the arthroscope inserted through the tibial tunnel into the femoral socket, you can redirect the trocar and sleeve to be more central in the socket. If this cannot be done, you can remove the sleeves and replace them after deepening the socket by 8 mm. Removal of the femoral rod may sometimes be difficult. When this happens, it is usually caused by the step between the shaft of the rod and the wider portion from the femur catching on the tibial tunnel. Changing the flexion angle of the knee to match the angle when the femoral socket was drilled and pushing the tibia posteriorly will allow the rod to slide out of the joint. Two key points for optimal functioning of this system are a snug fit (using 0.5 mm tolerance) of the graft and sutures into the femoral socket and cycling the graft under tension multiple times before fixing the tibial side in order to reduce potential creep from this system. Because the graft is not looped over the pins but rather is skewered by them and compressed against the socket walls, there is the potential for excessive creep in the early postoperative course if these steps are not followed.11 In this study, which was done without cycling the graft prior to testing, 5 mm of creep was found in the first 100 cycles, a large contrast to the manufacturer’s data indicating less than 2 mm of creep over 1000 cycles (assuming adherence to these details). 282

Immediately postoperatively a hinge brace is applied, with the hinges locked in extension. Icing is helpful for control of pain and swelling. We stress early full extension and have the patient keep the brace on, locked in extension at all times during the first week, with the exception of 6 hours per day in a continuous passive motion (CPM) machine. Ambulation with weight bearing as tolerated is allowed from day 1, with the brace locked in extension. We maintain this weightbearing protocol for a full 4 weeks after surgery but encourage brace removal after week 1, at any time when the patient is not weight bearing for motion and isometric strengthening. The CPM is discontinued after the 1-week postoperative visit, and formal physical therapy is begun. Quadriceps strengthening is carefully progressed under the supervision of the therapist for the first 4 months. Proprioceptive and agility training are delayed to the 4-month mark, and unrestricted return to athletics is permitted when 6 months has passed, if the thigh musculature is fully rehabilitated.

RESULTS This system for soft tissue ACL reconstruction, Rigidfix and IntraFix, reliably results in stable knees with 3 mm or less increased translation by KT-1000 at maximal manual pull in our early (2-year) follow-up. Endpoints on drawer and Lachman tests are high pitched. This system offers 360 degrees of circumferential fixation, which is radiolucent and absorbable. All these factors make soft tissue ACL reconstruction an attractive and reproducible procedure.

References 1. Yunes M, Richmond JC, Engels EA, et al. Patellar tendon versus hamstring tendons in ACL reconstruction: a meta-analysis. Arthroscopy 2001;17:248–257. 2. Brand J, Weiler A, Carborn DN, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 3. Pinczewski LA, Deehan DJ, Salmon LJ, et al. A five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:523–536.

Anterior Cruciate Ligament Reconstruction Utilizing the Rigidfix for Femoral-Sided Fixation 4. Goldblatt JP, Fitzsimmons SE, Richmond JC, et al. Reconstruction of the anterior cruciate ligament: meta-analysis of patellar tendon versus hamstring tendon autograft. Arthroscopy 2005;21:791–803. 5. Fu FH, Bennett CH, Latterman C, et al. Current trends in anterior cruciate ligament reconstruction. Part I: biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821–830. 6. Fu FH, Bennett CH, Ma CB, et al. Current trends in anterior cruciate ligament reconstruction. Part II: operative procedures and clinical correlations. Am J Sports Med 2000;28:124–130. 7. Spindler KP, Kuhn JE, Freedman KB, et al. Anterior cruciate ligament reconstruction autograft choice: bone-tendon-bone versus hamstring. Am J Sports Med 2004;32:1986–1995.

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8. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 9. Donahue TL, Howell SM, Hull ML, et al. A biomechanical evaluation of anterior and posterior tibialis tendons as suitable single-strand anterior cruciate ligament grafts. Arthroscopy 2002;18:589–597. 10. Raffo CS, Richmond JC. Hamstring anterior cruciate ligament reconstruction with rigid, 360-degree, near-aperture fixation. Tech Orthop 2005;20:1–5. 11. Ahmad CS, Gardner TR, Groh M, et al. Mechanical properties of soft tissue femoral fixation devices for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:635–640.

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39 CHAPTER

Michael Wagner Andreas Weiler

SUB PART III INTERFERENCE SCREW–BASED

Hamstring Tendon Interference Screw Fixation BIOMECHANICAL AND BIOLOGICAL CONSIDERATIONS The concept of interference screw fixation involves the parallel insertion of the screw to the graft in the tunnel, which allows compression of the graft to the bony tunnel wall and biological graft incorporation. Graft fixation using interference screws presents the “gold standard” when using a bone–patellar tendon–bone (BPTB) graft. This type of fixation combines high initial construct stiffness and early bony graft incorporation.1 These factors are generally required to allow for an accelerated rehabilitation, which has been demonstrated to improve clinical outcome.2 Soft tissue grafts, however, do not provide attached bone blocks for interference fit fixation. Additionally, tendon–bone healing generally takes longer for bony graft incorporation compared with bone–bone healing (4 to 6 weeks versus 6 to 12 weeks).3–7 Thus fixation of soft tissue grafts requires improved mechanical and biological boundary conditions for graft fixation compared with grafts with attached bone blocks.

Biomechanical Boundary Conditions Ideally, a graft fixation construct should be similar in strength and stiffness to the native human anterior cruciate ligament (ACL). Current fixation techniques demonstrate a wide range of in vitro measured graft fixation loads (200N to 1200N). However, today evidence is still limited 284

regarding real in vivo requirements for initial construct strength.8 Noyes et al calculated that the ACL is loaded up to 454N during activities of daily living,9 but other authors reported a high amount of good and excellent results with fixation types whose failure load is far below that anticipated value.10–12 For soft tissue graft fixation using biodegradable interference screws, failure loads of 250N to 800N have been demonstrated depending on screw length and insertion torque.13–15 Graft fixation generally is divided into anatomical (aperture or joint line fixation), nonanatomical, and semi-anatomical (Fig. 39-1), according to the location of fixation in relation to the joint line. Graft fixation directly at the joint line (site of the native ACL insertion) is called anatomical, whereas an extracortical fixation (e.g., staples, fixation buttons) is called nonanatomical. For example, transfixation devices or tibial interference screws that are not deeply inserted provide an intraosseous and thus a semi-anatomical mounting of the graft. This classification is important because the site of graft fixation determines the length of the complete graft fixation construct. The length of the native ACL is between 2.8 and 3.7 cm. Reconstruction of the anteromedial bundle of the ACL results in an intraarticular graft length of only approximately 2.5 to 3.2 cm. Using femoral and tibial nonanatomical fixation devices, the length of the graft fixation construct can easily reach 10 to 15 cm (see Fig. 39-1). In correlation to the distance between the fixation devices, reversible elastic longitudinal deformations of

Hamstring Tendon Interference Screw Fixation

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Biological Boundary Conditions

A

B

C

FIG. 39-1 A, Nonanatomical and indirect femoral and tibial fixation; B, anatomical and direct femoral and semianatomical and direct tibial fixation; C, anatomical and direct femoral and tibial fixation.

the graft have been demonstrated. This phenomenon also is known as the “bungee-cord effect.” Furthermore, sagittal intratunnel graft motion (reversible) might occur due to anteroposterior translation of the graft during knee flexion and extension using a nonanatomical or semianatomical graft fixation technique (“windshield-wiper effect”).15,16 Thus a long distance between the femoral and tibial fixation device results in low construct stiffness and graft–tunnel motion. Additionally, indirect and direct graft fixation should be distinguished (see Fig. 39-1). The concept of indirect graft fixation implicates the use of linkage material between graft and fixation device (e.g., suture loop of Endobutton fixation), whereas direct fixation means anchoring of the graft without any additional material except the fixation device itself (e.g., interference screws, staples, transfixation devices). Longitudinal irreversible graft deformation might occur using indirect fixation techniques due to stretch-out of linkage material (e.g., suture loop of Endobutton fixation) or suture attachment at the graft tissue.13,17,18 Longitudinal and sagittal graft–tunnel motion inhibits constant graft–tunnel contact at the tunnel entry site and thus compromises bony graft incorporation at the site of the native ACL insertion.5,19 Furthermore, graft–tunnel motion might lead to graft laceration at the tunnel entry site during dynamic loading20 and is a factor responsible for the development of tunnel enlargement.16 Although current literature is not consistent concerning the correlation between tunnel enlargement and postoperative knee stability16,21,22 in revision ACL reconstruction, tunnel enlargement is of clinical importance and should therefore be prevented. According to these considerations, interference screw fixation offers high construct stiffness and prevents intratunnel graft motion because it allows for direct and anatomical graft fixation at the level of the joint line combined with adequate initial fixation strength.5,23 Recent clinical data support the belief that clinical outcome can be improved with anatomical joint line fixation using interference screws for hamstring tendon grafts.24

In addition to correct tunnel placement, graft incorporation represents the main factor for long-term survival of an ACL reconstruction and is mainly influenced by the type of fixation. The surgical target is to create biological (and biomechanical) boundary conditions that allow for the restitution of a native ACL insertion site anatomy.5 The normal ACL insertion site consists of four zones (so-called direct ligament insertion). The first zone comprises the ligament, the second is characterized by fibrocartilage, the third zone consists of a mineralized cartilage tidemark, and the fourth is where the mineralized cartilage tidemark inserts into the subchondral bone plate.5 The design of this complex insertion anatomy allows distribution of longitudinal and shear forces from the ligament into the subchondral bone plate. The development of a direct ligament insertion at the level of the joint line has been demonstrated histologically in an animal model using anatomical soft tissue graft fixation with compression at the tunnel entry site (interference screws).25 In contrast, the use of a nonanatomical fixation technique in the same model showed the development of an indirect type of ligament insertion or only a delayed formation of a direct type of insertion.25 In indirect insertions, the surface of the ligament connects with the periosteum whereas the deeper layers connect to bone via Sharpey fibers (e.g., medial collateral ligament). This is of inferior mechanical competence compared with the direct ligament insertion.5 Thus it is reasonable to assume that neutralization of graft-tunnel motions using anatomical and direct interference screw fixation obviously improves osseous graft incorporation by means of the development of a native ACL insertion anatomy.25

Interference Screws Metallic interference screws initially were developed for fixation of grafts with attached bone blocks. These screws are threaded sharply to achieve good starting conditions for screw insertion and secure graft fixation. The use of this type of interference screw for soft tissue graft fixation might lead to laceration of the graft tissue during screw insertion, especially if high insertion torque is generated. Thus different round-threaded interference screws have been developed for soft tissue graft fixation.26,27 The first round-threaded metallic interference screw for direct fixation of soft tissue grafts was developed by L. Pinczewski, the round-headed cannulated interference screw (RCI)10,26 (Fig. 39-2). More recently, biodegradable interference screws have been developed and biomechanically as well as clinically tested for fixation of BPTB and soft tissue grafts.27,28 Soft tissue graft fixation using biodegradable interference screws was first described by Stähelin and Weiler.29 285

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FIG. 39-2 Different interference screws. A, Early metallic interference screw, sharp threaded; B, Sysorb biodegradable interference screw, round threaded; C, round-headed cannulated interference (RCI) screw, metallic, round threaded; MegaFix biodegradable interference screws, sharp threaded at the tip (D) and round threaded at the body (E). (A–C, From Weiler A, Hoffmann RF, Sudkamp NP, et al. Replacement of the anterior cruciate ligament. Biomechanical studies for patellar and semitendinosus tendon fixation with a poly[D,L-lactide] interference screw. Unfallchirurg 1999;102:115–123. D and E, By permission of KarlStorz, Tuttlingen, Germany.)

Biodegradable interference screws have been demonstrated to be advantageous compared with metallic screws by means of undistorted radiological imaging, uncompromised revision surgery, and minimized risk of graft laceration. However, one might consider that most currently available biodegradable interference screws do not show complete degradation and subsequent osseous replacement of the former implant site because they consist of slow degrading and high-molecular poly-L-lactide.27 Thus the use of intermediate degrading stereo-co-polymeric materials such as poly-(L-co-D,L-lactide) are preferable.27,30 The newest screw generations are sharply threaded just at the tip for easy starting conditions of the screw, followed by a blunt threading to prevent tissue laceration (see Fig. 39-2). Biodegradable as well as metallic

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interference screws are distributed in different sizes (diameter and length). Thus precise matching of graft and tunnel diameters can easily be performed. Mechanical studies have shown that a tight fit among the screw, the graft, and the tunnel is essential for sufficient fixation strength.13,31–33 When deciding to oversize a screw to improve fixation strength (particularly at the tibial site), an increased length has been demonstrated to be superior to an increased diameter.13,34 Furthermore, an oversized screw diameter increases the insertion torque in contrast to a longer screw. We therefore recommend increasing screw length instead of using massively oversized screws in diameter (e.g., Delta screws) to avoid violating the tendon tissue. In summary, hamstring tendon interference screw fixation offers the following advantages:

Hamstring Tendon Interference Screw Fixation


Anatomical and direct fixation
High stiffness of the graft fixation construct
Short graft, allowing the preservation of the gracilis tendon (especially with hybrid fixation; see later discussion)


No slippage under cyclical loading (improved by the use of tibial and femoral hybrid fixation; see later discussion)


Neutralization of graft tunnel motions
Prevention of synovial inflow into the tunnel
Allowance for uncompromised revision surgery (improved by using biodegradable screws)

TECHNICAL CONSIDERATIONS Graft Preparation Graft preparation is one of the essential surgical steps and should be performed carefully. Possible configurations include four-stranded grafts using a doubled semitendinosus and doubled gracilis tendon or the quadrupled semitendinosus tendon. Other possibilities are three- or fivestranded grafts. Because preservation of the gracilis tendon has been demonstrated to be beneficial35,36 and due to the fact that anatomical joint line fixation requires only a short graft (at least 7 cm) (Fig. 39-3), the use of a four-stranded semitendinosus tendon graft should be routinely achieved. To gain a sufficient length of the semitendinosus tendon, the tendon can be harvested including the periosteal distal insertion of the tendon. In most cases this results in a tendon length of at least 28 cm. If the semitendinosus tendon is very short (less than 26 cm) or thin, one can additionally harvest the gracilis tendon to create a four- or five-stranded semitendinosus/gracilis tendon graft. The four-stranded graft is prepared with the help of a suture board while arthroscopic preparation of the knee is performed. The proximal and distal endings of the

FIG. 39-3 Quadrupled semitendinosus tendon autograft with EndoPearl attached to the femoral end.

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semitendinosus tendon are armed with #2 polyester sutures in a whipstitch fashion (Fig. 39-4). Care has to be taken to pull all slack out of each suture pass. Then the construct should be manually tensioned to allow potential slippage to be taken out of the construct (Fig. 39-5). The tendon is then looped over itself using the so-called “W-technique,” and a polyester passing suture is brought through each loop (Fig. 39-6). The looped tendons are then pulled through a graft sizer (Fig. 39-7). The resulting diameter of the graft is usually between 7 and 9 mm. A tight fit of the graft in the tunnel generally is required to improve fixation strength and graft incorporation. The diameter of the graft is a given value, which needs to be known before tunnel creation. When hybrid fixation (see later discussion) is used, sizing of the graft in increments of 1 mm is sufficient; if interference screw fixation is used solely, we recommend sizing in increments of 0.5 mm33 to allow for the required tight fit. A marking suture using #0 absorbable suture has to be set 2 cm from the femoral end of the graft to show the surgeon if the graft is inserted deep enough into the femoral tunnel. The side effect of the suture is that good passage of the graft in the tunnel is ensured, and twisting of the graft around the screw during its insertion is prevented (see later discussion; see also Fig. 39-3). If femoral hybrid fixation using the EndoPearl (Linvatec, Largo, FL) device is desired, the pearl is tied to the femoral end of the graft (see Fig. 39-3). It is important that the knot fixing the pearl to the graft is not placed at the side of the screw, which would result in an increased graft diameter, possibly leading to problems during graft insertion. The tibial end of the graft is sutured in a baseballstitch technique using #0 absorbable sutures to ease the insertion of the tibial screw and to increase initial tibial graft fixation strength (see Fig. 39-3).

Femoral Interference Screw Fixation Tunnel Preparation According to the current literature the femoral tunnel should be drilled in the ten-o’clock position for right knees or in the two–o’clock position for left knees.37–39 Arnold et al demonstrated that this position cannot or can hardly be achieved when using the conventional transtibial techniques (single incision).40 Thus we routinely use the anteromedial portal technique in all ACL reconstruction procedures because it allows for an anatomical lateral tunnel placement. In the anteromedial tunnel technique, we create the femoral tunnel first in approximately 120 to 130 degrees of flexion (Fig. 39-8). Thus tunnel direction is directed more to the center of the bone and away from the posterior femoral cortex, which prevents posterior breakage of the tunnel wall. 287

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FIG. 39-4 Arming the tendon with #2 polyester sutures in whipstitch fashion.

FIG. 39-5 Manual tensioning of the armed tendon to prevent later slippage of the sutures.

FIG. 39-7 Measuring the diameter of the graft.

FIG. 39-6 To prepare a quadrupled graft, the tendon is looped over itself using the so-called “W-technique” and a polyester passing suture is laid through each loop.

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As this amount of knee flexion only hardly can be achieved when using a standard leg holder, we routinely use a lateral support at the level of the thigh and put the leg on the operating table in maximum knee flexion (Fig. 39-9). In ACL reconstruction using hamstring tendons, the graft diameter has to be known before tunnel creation to allow for a tight fit between graft and tunnel wall, in contrast to BPTB grafts for which 8- to 10-mm tunnels are routinely used as determined by the size of the harvested bone blocks.

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Screw Insertion

FIG. 39-8 In the anteromedial tunnel technique, the femoral tunnel is created in approximately 120 to 130 degrees of flexion to prevent posterior breakage of the tunnel wall. (By permission of KarlStorz, Tuttlingen, Germany.)

During femoral screw insertion it is of great importance to control knee flexion to prevent screw divergence, which might result in decreased fixation strength, and to allow for an easy screw start. If the anteromedial portal technique is used, the knee flexion angle has to be exactly the same as it was during tunnel creation. If the transtibial technique is used, one needs to find the desired knee flexion angle for proper screw insertion. In this situation a standardized flexion of 120 degrees might not be appropriate. We therefore recommend palpating the tunnel with a nitinol wire or the tip of the screwdriver prior to screw insertion to ensure parallel screw placement. In addition to correct direction of screw insertion, other surgical details can ease femoral screw insertion:


A nitinol guidewire can be used to identify tunnel direction and to secure correct screw placement by insertion of the screw over the wire (cannulated screwdriver necessary).


Tunnel direction can be verified using the screwdriver. Furthermore, the place of screw insertion can be dilated a little bit when the graft is already inserted using the screwdriver or a small dilator (4 mm) (Fig. 39-10). This technique preconditions the tunnel for screw insertion and correct placement.


Notching of the femoral tunnel wall using a special instrument (Fig. 39-11) eases screw insertion and secures posterior positioning of the graft in the tunnel.

FIG. 39-9 Knee held in maximum flexion during creation of the femoral tunnel via the anteromedial portal.

The standard sizing when using interference screw fixation at the femoral site alone is: Tunnel diameter ¼ Graft diameter ¼ Screw diameter

The length of the screw should be 23 to 25 mm to achieve sufficient initial fixation strength.

Concerning the depth of screw insertion into the femoral tunnel, there is a main difference between metallic and biodegradable interference screws. Biodegradable interference screws should be countersunk a few millimeters (2 to 3 mm) below the surface to allow for overgrowth of connective tissue. If metallic interference screws are advanced too deep, later hardware removal (e.g., in case of revision reconstruction) might be complicated. The use of round-headed interference screws on the femoral site, as recommended in earlier years for BPTB graft fixation, is not recommended anymore because a prominent screw head might impinge with the graft in full extension. If a metallic screw head is countersunk, later revision reconstruction might be compromised because screw removal can create large bone defects due to the head of the screw needing to be exposed for removal.

Interference Screw Position On the femoral site, screw position generally is anterior to the graft to allow anatometric posterior placement of the graft in the tunnel. Problems in femoral hamstring tendon interference screw fixation might occur if the graft tends to rotate around 289

Anterior Cruciate Ligament Reconstruction

FIG. 39-10 Dilation of the screw site using a small dilator (4 mm), followed by screw insertion.

the screw during its insertion; this might lead to an undesired position of the graft (Fig. 39-12). When using a standard right-threaded screw in right knees, the graft might rotate toward an anterolateral position, resulting in too-anterior graft placement and lateral wall impingement. Thus Pinczewski et al could show a difference of clinical outcome between right and left knees after hamstring tendon interference fit fixation.41 Subsequently, a reversed-threaded interference screw was developed for use in right knees.41 However, in a left knee with a conventional screw or in a right knee with a reversed screw, the graft might rotate toward the 12-o’clock position, which might lead to compromised 290

control of knee rotation.40,42 We therefore recommend preventing screw rotation completely. Techniques to minimize the risk of graft rotation during interference screw insertion include the following:


Tight suturing of the proximal end of the graft (see Fig. 39-3). This decreases graft rotation by stabilizing the bundles of the graft and preventing strands of the graft from being caught by the surface of the screw.


Hybrid fixation. Femoral hybrid fixation using the EndoPearl device allows undersizing of screw diameter, resulting in decreased insertion torque without

Hamstring Tendon Interference Screw Fixation

39

FIG. 39-11 Notching of the anterior edge of the femoral tunnel entry to facilitate screw insertion and anterior placement of the screw. A, Schematic picture. B–G, Intraoperative views. (A, By permission of KarlStorz, Tuttlingen, Germany.)

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FIG. 39-12 Rotation of the graft to an undesired 12-o’clock position in femoral hamstring tendon interference screw fixation in a left knee.

compromising fixation strength. Decreased insertion torque minimizes the risk of graft rotation during screw insertion.


Notching the screw insertion site (see Fig. 39-11).
Bone wedge technique (Fig. 39-13). The use of this technique prevents the graft from rotation during screw insertion and allows for 360 degrees of bone contact around the graft. At the anterosuperior tunnel aperture, a thin (2 to 4 mm) bone wedge can be detached using a special chisel (Fig. 39-14). The screw is then advanced between the tunnel wall and the bone wedge. Care has to be taken because a very large bone wedge might decrease fixation strength; thus hybrid fixation is recommended.

Possible Problems During Screw Insertion Normally the interference screw should start easily with only low manual pressure. During further screw insertion, the screw should find the way parallel to the graft without any manual pressure, just by rotation of the screwdriver. If the screw does not start correctly, the surgeon often tends to push the screw against the graft with the risk of tissue laceration. Because one of the main reasons for disturbed screw insertion is a wrong knee flexion angle, the screw should be removed and the flexion angle controlled prior to inserting the screw again. Furthermore, problems during screw insertion might occur due to high bone density because very high insertion torque might be created in this situation. If metal interference screws are used, the danger of graft laceration during screw insertion has to be considered. Therefore oversized screws are not recommended on the femoral site. Another problem might occur if the screw is too long (more than 25 mm) or the tunnel is too short (less than 25 mm). In these cases, shorter screws (e.g., 19 mm) can be used or the tunnel needs to be lengthened. When biodegradable 292

interference screws are used, high-insertion torque might result in breakage of the screw. Thus the screw should be changed to a smaller diameter if possible breakage is recognized. If the screw is inserted already for two-thirds of its length when it breaks, sufficient fixation strength can be assumed if hybrid fixation is used. In contrast, low insertion torque generally results in low fixation strength. Different factors can be responsible for a low insertion torque, as follows:


Low bone density or inappropriate matching of tunnel diameter and screw. In these cases a bigger screw should be chosen or a second screw can be inserted (sandwich technique).


Posterior blowout of the femoral tunnel wall due to far posterior tunnel placement. In these cases the fixation technique has to be changed (e.g., Endobutton).


The screw is accidentally inserted into the posterolateral recess. This problem might occur due to poor intraarticular visualization and improper knee flexion during screw insertion.

Femoral Hybrid Fixation An important method that further minimizes graft–tunnel motions and improves initial fixation strength as well as construct stiffness is the so-called hybrid fixation.31,43 The principle of hybrid fixation is to combine two fixation techniques at one site.31 At least one of the devices used should be able to achieve sufficient fixation strength alone. This device is combined with a second technique in order to neutralize its possible biomechanical and biological disadvantages (e.g., graft–tunnel motion) (Table 39-1). On the femoral site, graft fixation generally is more forgiving compared with the tibia from a mechanical point of view. However, disturbed biological incorporation is a

Hamstring Tendon Interference Screw Fixation

39

FIG. 39-13 Bone wedge technique. At the anterosuperior position of the tunnel entry site, a thin bone wedge is detached using a special chisel (A). The screw then is advanced between the tunnel wall and this bone wedge (B–D).

problem of femoral fixation due to the higher graft–tunnel motions.25 We therefore recommend aperture fixation on the femur to optimize biological boundary conditions. In order to minimize possible problems of interference screw fixation, such as tissue laceration and graft rotation, femoral hybrid fixation allows for the use of an undersized screw to solve these problems. For femoral hybrid fixation with interference screws, a biodegradable spherical device, the EndoPearl, has been

developed (see Fig. 39-3). The EndoPearl is tied to the femoral end of the graft and achieves an internal locking between the graft and the tip of the interference screw (Fig. 39-15). Thus it increases initial fixation strength, especially in cases of tunnel enlargement (revision reconstruction) or low bone density. Clinically it has been shown to improve knee stability compared with interference screw fixation alone.44 If this type of femoral hybrid fixation is used, the femoral tunnel should be created 1 cm deeper

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FIG. 39-14 Specially designed chisel for the bone wedge technique. (By permission of KarlStorz, Tuttlingen, Germany.)

TABLE 39-1 Possibilities for Hybrid Fixation Type of Fixation

Possible Methods

Femoral hybrid

Interference screw and EndoPearl

fixation

Suture button and interference screw Suture button and cancellous bone plug Transfixation and interference screw Transfixation and cancellous bone plug

Tibial hybrid fixation Interference screw and suture to bony bridge Interference screw and suture button

interference screw fixation in revision cases as well. As another alternative, a cortical bone plug can be tied to the femoral end of the graft.45 Femoral hybrid fixation with interference screws also can be achieved with the additional use of an Endobutton. In these cases, especially if a continuous loop is used, the screw acts only to neutralize graft tunnel motion and prevent synovial inflow. Thus the use of small screws (5 to 6 mm) is sufficient.

Interference screw and staples Cancellous bone plug and suture button

Tibial Interference Screw Fixation

Cancellous bone plug and suture to bony bridge Cancellous bone plug and tying of sutures over

Tunnel Preparation

screw

The tibial tunnel is created in the standard fashion; we prefer a posterior cruciate ligament (PCL)–referenced tibial drill guide. The first drill bit is undersized approximately 2 mm to the desired tunnel diameter. This allows for later correction of the tibial tunnel after impingement testing and reduces the risk of a spine fracture or apical spine fragmentation. Furthermore, if the initially drilled tunnel is undersized, the final steps can be dilated if low bone density is recognized during drilling. On the tibial site, screw position is routinely chosen to be posterior to the graft (see Fig. 39-15). This position prevents the screw from anterior graft impingement if it is accidentally inserted too deep. The tibial screw can be positioned anterior to the graft if the tibial tunnel is placed slightly too far anterior to push the graft posteriorly and to prevent a notch impingement.

than normally recommended (35 mm instead of 25 mm). Additionally the chosen diameter of the screw can be 1 to 2 mm less than the tunnel diameter without compromising fixation strength. This is advantageous because it decreases the risk of tissue laceration (insertion torque) and reduces screw rotation without compromising initial fixation strength. Thus the standard sizing when using femoral hybrid fixation with the EndoPearl is: Tunnel diameter ¼ Graft diameter ¼ Screw diameter  1mm

As an alternative, tunnel diameter can be increased and screw size chosen according to the graft diameter when hybrid fixation is used. This allows for hamstring tendon

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39

FIG. 39-15 A, Magnetic resonance image (MRI) demonstrating contact between the EndoPearl and the tip of the interference screw (arrow) to achieve an internal locking. B, MRI demonstrating position of the tibial screw posterior to the graft (arrow).

Matching of Tibial Tunnel and Screw Diameter

Tibial Hybrid Fixation

When using interference screw fixation at the tibial site alone, the diameter of the screw should be 1 mm larger than the diameter of the tunnel. For the tibial site, a longer screw (28 to 35 mm) is beneficial to avoid oversizing the screw by 2 mm. However, today it is generally recommended that hybrid fixation at the tibial site should always be performed when using interference screw fixation of soft tissue grafts. Therefore, when using tibial hybrid fixation with interference screws, the standard procedure is:

When interference screw fixation is used for soft tissue grafts, some authors are concerned about a possible fixation slippage at the tibial fixation site even though fixation strength at the femoral site is considered sufficient.13,18,32,46 The risk of graft slippage on the tibial site can be nicely compensated with oversized screws, or better, by using hybrid fixation on the tibia, especially in females.34,47 An easy and safe method of tibial hybrid fixation is to tie the holding sutures of the graft over a bony bridge

Graft diameter ¼ Tunnel diameter ¼ Screw diameter ðlonger screw ½e:g:; 28 mmÞ

If one prefers using interference screw fixation alone, the following sizing is recommended: Graft diameter ¼ Tunnel diameter ¼ Screw diameter ðlonger screw ½e:g:; 28 mmÞ þ1 mm

Possible Problems during Screw Insertion A specific problem at the tibial site is the “blind” insertion of the screw. Thus the risk of inserting the screw not parallel to the graft is increased compared with the femoral site. Furthermore, it might easily happen that the screw is not inserted between the graft and the tunnel wall but instead pushes the graft forward during its insertion. To prevent this accidental graft dislocation, the surgeon should hold the holding sutures of the graft tightly during screw insertion. After tibial screw insertion we recommend controlling graft and screw placement by an intratunnel view using the arthroscope (Fig. 39-16).

FIG. 39-16 Intratunnel view to control tibial interference screw and graft position.

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FIG. 39-17 Tibial backup fixation by suturing the linkage material over a bony bridge. A, A monocortical hole is prepared 2 cm distally from the tibial tunnel using the screwdriver. B, The cancellous bone is tunneled using a curved clamp. C and D, A suture loop is passed from the distal to the proximal hole using a needle. E–I, One strand of each attached suture is passed through the holes using the suture loop and tied over the created bony bridge. J, The knot should be countersunk into the tibial tunnel to avoid the development of a subcutaneous granuloma. t, Tibial tunnel. (A–D, By permission of KarlStorz Tuttlingen, Germany.)

after the tibial screw is inserted (Fig. 39-17). For this a monocortical drill hole is created 2 cm distally of the tibial tunnel exit site. Then one strand of each suture is passed through the hole and tied over the created bony bridge.48

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In cases with a low insertion torque of the interference screw, the use of a suture button instead of the suture over bony bridge might be beneficial (Fig. 39-18). Manual rotation of the button tightens the linkage material, thus safely preventing graft slippage.

Hamstring Tendon Interference Screw Fixation

39

FIG. 39-18 Tibial hybrid fixation using a suture. A–D, The tibial tunnel exit site first has to be prepared using a special instrument. E–G, The sutures are passed through the holes of the fixation button and tied over the button. H and I, Manual rotation of the button using a special instrument tightens the linkage material. (From Strobel M. Manual of arthroscopic surgery. Berlin, 2001, Springer-Verlag.)

References 1. Kurosaka M, Yoshiya S, Andrish J. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med 1987;15:225. 2. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292–299. 3. Grana WA, Egle DM, Mahnken R, et al. An analysis of autograft fixation after anterior cruciate ligament reconstruction in a rabbit model. Am J Sports Med 1994;22:344–351. 4. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 5. Weiler A, Scheffler S, Apraleva M. Healing of ligament and tendon to bone. In Walsh W (ed): Repair and regeneration of ligaments, tendons and capsule. Totawa, New Jersey, 2005, The Humana Press, pp 201–231. 6. Weiler A, Hoffmann RF, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135.

7. Weiler A, Peine R, Pashmineh-Azar A, et al. Tendon healing in a bone tunnel. Part I: biomechanical results after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:113–123. 8. Rupp S, Hopf T, Hess T, et al. Resulting tensile forces in the human bone-patellar tendon-bone graft: direct force measurements in vitro. Arthroscopy 1999;15:179–184. 9. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg 1984;66A:344–352. 10. Pinczewski LA, Deehan DJ, Salmon LJ, et al. A five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:523–536. 11. Roe J, Pinczewski LA, Russell VJ, et al. A 7-year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction: differences and similarities. Am J Sports Med 2005;33:1337–1345. 12. Shelbourne KD, Patel DV. ACL reconstruction using the autogenous bone-patellar tendon-bone graft: open two-incision technique. Instr Course Lect 1996;45:245–252.

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Anterior Cruciate Ligament Reconstruction 13. Scheffler SU, Sudkamp NP, Gockenjan A, et al. Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: the impact of fixation level and fixation method under cyclic loading. Arthroscopy 2002;18:304–315. 14. Selby JB, Johnson DL, Hester P, et al. Effect of screw length on bioabsorbable interference screw fixation in a tibial bone tunnel. Am J Sports Med 2001;29:614–619. 15. Weiler A, Scheffler SU, Sudkamp NP. [Current aspects of anchoring hamstring tendon transplants in cruciate ligament surgery.]. Chirurg 2000;71:1034–1044. 16. Höher J, Möller H, Fu F. Bone tunnel enlargement after anterior cruciate ligament reconstruction: fact or fiction. Knee Surg Sports Traumatol Arthrosc 1998;6:231–240. 17. Höher J, Scheffler SU, Withrow JD, et al. Mechanical behavior of two hamstring graft constructs for reconstruction of the anterior cruciate ligament. J Orthop Res 2000;18:456–461. 18. Magen H, Howell S, Hull M. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 19. Natsu-Ume T, Shino K, Nakata K, et al. Endoscopic reconstruction of the anterior cruciate ligament with quadrupled hamstring tendons: a correlation between MRI changes and restored stability of the knee. J Bone Joint Surg 2001;83B:837–840. 20. Toritsuka Y, Shino K, Horibe S, et al. Second-look arthroscopy of anterior cruciate ligament grafts with multistranded hamstring tendons. Arthroscopy 2004;20:287–293. 21. Buelow JU, Siebold R, Ellermann A. A prospective evaluation of tunnel enlargement in anterior cruciate ligament reconstruction with hamstrings: extracortical versus anatomical fixation. Knee Surg Sports Traumatol Arthrosc 2002;10:80–85. 22. Stange R, Russel V, Salmon L, et al. Tibial tunnel widening after ACL reconstruction: a 2 and 5 year comparison of patellar tendon autograft and 4-strand hamstring tendon autograft. Arthroscopy Assoc N Am 2001; 20th Annual Meeting:67. 23. Weiler A, Hoffmann RF, Stahelin AC, et al. Hamstring tendon fixation using interference screws: a biomechanical study in calf tibial bone. Arthroscopy 1998;14:29–37. 24. Wagner M, Kaab MJ, Schallock J, et al. Hamstring tendon versus patellar tendon anterior cruciate ligament reconstruction using biodegradable interference fit fixation: a prospective matched-group analysis. Am J Sports Med 2005;33:1327–1336. 25. Weiler A, Unterhauser F, Faensen B, et al. Comparison of tendon-tobone healing using extracortical and anatomic interference fit fixation of soft tissue grafts in a sheep model of ACL reconstruction. Trans Orthop Res Soc 2002;48:173. 26. Scranton P, Pinczewski L, Auld M, et al. Outpatient endoscopic quadruple hamstring anterior cruciate ligament reconstruction. Operative Tech Orthop 1996;6:177–180. 27. Weiler A, Hoffmann R, Stähelin A, et al. Current concepts: biodegradable implants in sports medicine—the biological base. Arthroscopy 2000;16:305–321. 28. Weiler A, Windhagen HJ, Raschke MJ, et al. Biodegradable interference screw fixation exhibits pull-out force and stiffness similar to titanium screws. Am J Sports Med 1998;26:119–126. 29. Stähelin A, Weiler A. All-inside anterior cruciate ligament reconstruction using semitendinosus tendon and soft threaded biodegradable interference screw fixation. Arthroscopy 1997;13:773–779. 30. Hunt P, Unterhauser FN, Strobel MJ, et al. Development of a perforated biodegradable interference screw. Arthroscopy 2005; 21:258–265.

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31. Brand J, Weiler A, Caborn D, et al. Graft fixation in cruciate ligament surgery: current concepts. Am J Sports Med 2000;28:761–774. 32. Brand JC Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 33. Steenlage E, Brand JC Jr, Johnson DL, et al. Correlation of bone tunnel diameter with quadrupled hamstring graft fixation strength using a biodegradable interference screw. Arthroscopy 2002;18:901–907. 34. Weiler A, Hoffmann R, Siepe C, et al. The influence of screw geometry on hamstring tendon interference fit fixation. Am J Sports Med 2000;28:356–359. 35. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 36. Tashiro T, Kurosawa H, Kawakami A, et al. Influence of medial hamstring tendon harvest on knee flexor strength after anterior cruciate ligament reconstruction. A detailed evaluation with comparison of single- and double-tendon harvest. Am J Sports Med 2003;31:522–529. 37. Hefzy M, Grood E, Noyes F. Factors affecting the region of most isometric femoral attachments. Am J Sports Med 1989;17:208–216. 38. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304. 39. Sapega AA, Moyer RA, Schneck C, et al. Testing for isometry during reconstruction of the anterior cruciate ligament. Anatomical and biomechanical considerations. J Bone Joint Surg 1990;72A:259–267. 40. Arnold MP, Kooloos J, van Kampen A. Single-incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 41. Musgrove TP, Salmon LJ, Burt CF, et al. The influence of reversethread screw femoral fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendon. Am J Sports Med 2000;28:695–699. 42. Musahl V, Plakseychuk A, Vanscyoc A, et al. Varying femoral tunnels between the anatomical footprint and isometric positions. Am J Sports Med 2005;33:712–718. 43. Tsuda E, Fukuda Y, Loh JC, et al. The effect of soft tissue graft fixation in anterior cruciate ligament reconstruction on graft-tunnel motion under anterior tibial loading. Arthroscopy 2002;18:960–967. 44. Arneja S, Froese W, MacDonald P. Augmentation of femoral fixation in hamstring anterior cruciate ligament reconstruction with a bioabsorbable bead: a prospective single-blind randomized clinical trial. Am J Sports Med 2004;32:159–163. 45. Nagarkatti DG, McKeon BP, Donahue BS, et al. Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation. Am J Sports Med 2001;29:67–71. 46. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 47. Hill PF, Russell VJ, Salmon LJ, et al. The influence of supplementary tibial fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendons in female patients. Am J Sports Med 2005;33:94–101. 48. Weiler A, Richter M, Schmidmaier G, et al. The EndoPearl device increases fixation strength and eliminates construct slippage of hamstring tendon grafts with interference screw fixation. Arthroscopy 2001;17:353–359.

Anatomical Retroscrew Anterior Cruciate Ligament Fixation: Single- and DoubleBundle Anterior Cruciate Ligament Reconstruction with Retroscrew Biointerference in a Single Femoral Socket The concept of anatomic graft positioning for anterior cruciate ligament reconstruction (ACL) has been previously described by many authors.1–6 In the past, anatomical graft tunnels were believed to obtain an optimal ACL reconstruction; the position of the graft within bone tunnels had to avoid the intercondylar roof and wall impingement. Studies have documented the landmarks for the placement of endoscopic tunnels in anatomical reconstructions through a full knee range of motion that will avoid impingement.7,8 Recently, issues regarding graft fixation position have become important. Experimental and clinical trials have shown that anatomical graft fixation and position at or near the origin and insertion of the native ACL in contrast to nonanatomical fixation position will (1) minimize graft tension, (2) minimize graft length change, (3) produce a more stable reconstruction through full knee range of motion, and (4) avoid anteroposterior, sagittal, windshield wiper–type graft motion.1,2,4,7–10 Five-year follow-up studies comparing anatomical and nonanatomical fixation for ACL reconstruction have shown absence of tunnel expansion up to 5 years with an anatomically fixed graft at the intraarticular tibial tunnel orifice (Fig. 40-1)5,6,8,11,12 The Retroscrew (Arthrex, Naples, FL) (Fig. 40-2) is inserted into the tibial tunnel in an inside-out position so that the head of the screw achieves aperture fixation at the intraarticular tunnel orifice. Standard interference screw fixation is used on the femoral side. The Retroscrew is beneficial during tensioning because

unlike an antegrade screw, the Retroscrew will pull the graft tighter into the tunnel, especially during tensioning. Morgan et al4 first described an “all-inside” technique for ACL reconstruction that addressed the issues of anatomical fixation. However, the procedure was not popular because of its technically demanding nature3,5,6,13 (Fig. 40-3). Graft choices for this technique include quadriceps tendon autograft, quadrupled hamstring autograft, Achilles allograft, hamstring allograft, and tibialis tendon allograft. Once a graft has been selected, prepared, and sized, the appropriate tunnels are placed: 7 mm anterior to the posterior cruciate ligament (PCL) between the tibial spines for the tibia and at the 2-o’clock position for a left knee or 10-o’clock position for a right knee on the lateral intercondylar wall.

40 CHAPTER

Steven Gorin Craig D. Morgan David Caborn

OPERATIVE TECHNIQUE: SINGLE FEMORAL SOCKET, SINGLE-BUNDLE GRAFT Once the appropriate anatomical bone tunnels have been placed, the graft is passed in a routine fashion. Femoral fixation may be achieved using an interference screw equal to the diameter of the tunnel placed through the anteromedial portal with the knee in hyperflexion. Alternatively, femoral fixation may be accomplished with a specially designed, cannulated Retroscrew driver

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FIG. 40-1 A, An all-inside anterior cruciate ligament (ACL) reconstruction with a quadriceps tendon autograft fixed anatomically at the intraarticular tibial and femoral socket orifices. Retrograde and antegrade headed titanium interference screws (Arthrex) were used in the tibial and femoral sockets, respectively. B, A lateral radiograph of the same case illustrating anatomical interference screw positioning.

300

FIG. 40-2 The femoral and tibia Retroscrews are shown. The screws are tethered by a #2 Fiberwire suture.

(Arthrex) passed through the tibial tunnel to achieve parallel interference screw fixation. This is performed using a preloaded Fiberstick Suture (Arthrex) withdrawn from the tip of the screw driver and out the anteromedial portal (see Fig. 40-3). The #2 suture is then passed through the cannulation of the Retroscrew, and a 3-mm Mulberry knot is tied to prevent the screw from disengaging the driver. Intraarticular passage of the femoral Retroscrew from the anteromedial portal is facilitated with the aid of a flexible slotted cannula (shoehorn cannula, Arthrex) at the same time as the suture exiting the handle portion of the screwdriver is pulled (Fig. 40-4). The shoehorn cannula avoids hang-up of the screw in the fat pad. This is used to secure and lead a femoral Retroscrew (7 to 10 mm  20 mm) onto the driver tip. Once the screw has been securely placed onto the end of the driver, the suture may be removed. With the leg in approximately 90 degrees of flexion, the screw is advanced into the femoral socket to secure the femoral side of the graft. Tibial fixation can next be performed by placing a tibial Retroscrew equal to the tunnel diameter. As previously described, the tibial Retroscrew (8 to 10 mm  20 mm) is placed onto the driver tip over a #2 Fiberwire suture from the medial portal. It is important that the screwdriver tip be anterior to the graft and free of all soft tissue. Obscuring the tip will prevent seating of the screw on the driver. Once inside the joint, the screw is “flipped” onto the driver by pulling the suture exiting the driver handle at the same time as the driver tip is lowered into the aperture (Fig. 40-5). The screw is then secured to the driver by wrapping the exiting suture around the grommets on the driver handle.

Anatomical Retroscrew Anterior Cruciate Ligament Fixation

40

FIG. 40-4 Tibial Retroscrew insertion via anteromedial portal assisted by flexible slotted cannula (shoehorn cannula).

FIG. 40-3 A, A 2.5-year follow-up magnetic resonance image (MRI) of an all-inside quadriceps tendon autograft anterior cruciate ligament (ACL) reconstruction using bioabsorbable interference screws. Graft and screw resorption up to the intercondylar floor where biological graft incorporation appears similar to a native ACL without tunnel widening. B, Radiograph 6 years after a quadriceps tendon autograft ACL reconstruction illustrates the absence of tunnel expansion on either the femoral or tibial side of the joint.

The graft is then tensioned as the screw is advanced counterclockwise until its head is flush with the intraarticular aperture of the tibial tunnel. With the arthroscope turned toward the tibial surface, the knee may be extended to near full extension as the screw is advanced into the top of the tibial tunnel. If additional tibial fixation is desired, a second

FIG. 40-5 Placement of tibia Retroscrew into the aperture of the tibial tunnel.

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Anterior Cruciate Ligament Reconstruction interference screw may be placed from outside in, antegrade and posterior to the graft. This will result in an interlocking screw–graft fixation construct.

OPERATIVE TECHNIQUE: SINGLE FEMORAL SOCKET, DOUBLE-BUNDLE GRAFT The simplicity of this technique is what makes it appealing. Only minor modifications are made to the previously described single-bundle procedure. Our preferred graft source for the double-bundle technique is a two-limbed tibialis tendon allograft. During preparation, it is recommended that it be prepared in the manner described by Charlick and Caborn.14 Specifically, this may be carried out by suturing (#2 Fiberwire) 20 mm to either side of the midline of the folded soft tissue graft (Fig. 40-6). If a hamstring graft is chosen, the semitendinosus and gracilis tendons should first be sutured together under tension to create a two-limbed, folded graft. Further suturing is performed distally after accommodating 30 to 35 mm for the intraarticular portion of the graft. This additional whipstitch aids in controlling the anteromedial bundle

(AMB) and posterolateral bundle (PLB) as they are oriented into the femoral and tibial tunnels. Caborn stitching has been shown to increase pullout to failure by approximately 30% when using interference screw fixation for soft tissue grafts.14 After standard femoral and tibial socket preparation, to create the double-bundle socket on the femur, a notching device is used to create two slots on the femoral socket intraarticular orifice, for the AMB and PLB of the ACL graft, respectively. The slots can be further delineated using a motorized bur or shaver or a curved curette (Fig. 40-7). With the knee flexed 90 degrees, the AMB slot is made at the 10- or 2-o’clock position and the PLB slot is made at the 4- or 8-o’clock position within the circumference of the tunnel orifice. Each slot is typically 6 to 7 mm in width. The graft is then passed in routine fashion using a Beath pin. While the graft is held into the tunnel by an assistant, the limbs of the graft are rotated into their respective notches. The AMB is retraced by a probe from the anteromedial portal. Femoral fixation is then carried out with a concentrically placed femoral Retroscrew placed central between the bundles and secured into position by the driver, which is passed through the tibial tunnel as described

Midline of graft 20 mm

30 mm

20 mm 20 mm

30 mm

20 mm

Graft passing suture

FIG. 40-6 Demonstration of the two-bundle soft tissue anterior cruciate ligament (ACL) graft with suture preparation to accommodate femoral and tibia interference screws. Note the suture pattern performed to enhance thread contact of the interference screw. This preparation also assists in orienting the bundles on the femoral and tibial attachment sites.

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Anatomical Retroscrew Anterior Cruciate Ligament Fixation

40

FIG. 40-7 Single socket, double-bundle femoral socket preparation featuring specific notches created for the anteromedial and posterolateral bundles.

previously (Fig. 40-8). As the screw is advanced in the tunnel, the graft strands will seek the two-bundle origin of the ACL in their respective slots (Fig. 40-9). The graft strands are then anatomically positioned directly anterior and posterior to one another within the tibial tunnel (AMB, anterior; PLB, posterior). Tibial fixation is carried out using a tibial Retroscrew, as previously described, medial to the strands with the knee flexed approximately 70 degrees. Both bundles are equally tensioned at 70 degrees of flexion prior to tibial Retroscrew fixation. Secondary backup fixation can be applied with a

FIG. 40-8 Concentric placement of femoral Retroscrew separating the graft into the anteromedial and posterolateral bundle positions.

FIG. 40-9 Final inspection of the single-tunnel, double-bundle, soft tissue anterior cruciate ligament (ACL) reconstruction.

bicortical post and washer or a second interference screw secured to the distal tibial cortex.

References 1. Barber FA. Flipped patellar tendon autograft anterior cruciate ligament reconstruction. Arthroscopy 2000;16:483–490. 2. Ishibashi Y, Rudy T, Livesay G, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system. Arthroscopy 1997;13:177–182. 3. Leitman EH, Morgan CD, Grawl DM. Quadriceps tendon anterior cruciate ligament reconstruction using the all-inside technique. Operative Tech Sports Med 1999;7:179–188. 4. Morgan CD, Kalman VH, Grawl D. Isometry testing for anterior cruciate ligament reconstruction revisited. Arthroscopy 1995;11:647–659. 5. Palmeri M, Morgan CD. The all-inside anterior cruciate ligament reconstruction: a double socket approach. Operative Tech Orthop 1996;6:161–176. 6. Stahelin A, Weiler A. All-inside anterior cruciate ligament reconstruction using semitendinosus tendon and soft threaded biodegradable interference screw fixation. Arthroscopy 1997;13:773–779. 7. Howell SM, Clark JA. Tibial tunnel placement in ACL reconstructions and graft impingement. Clin Orthop 1992;283:187–195. 8. Morgan CD, Kalman VH, Grawl DM. Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction. Arthroscopy 1995;11:275–288. 9. Howell SM, Clark JA, Farley TE. A rationale for predicting anterior graft impingement by the intercondylar roof. A magnetic resonance imaging study. Am J Sports Med 1991;19:276–281. 10. L’Insalata JC, Klatt B, Fu FH, et al. Tunnel expansion following anterior cruciate ligament reconstruction: a comparison of hamstring and patellar tendon autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234–238. 11. Weiler A, Hoffman RFG, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135.

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Anterior Cruciate Ligament Reconstruction 12. Weiler A, Peine R, Pashmineh-Azar A, et al. Tendon healing in a bone tunnel. Part I: biomechanical results after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:113–123. 13. Morgan CD. Quadriceps tendon autograft for ACL reconstruction. In Jackson D (ed): Master techniques in orthopaedic surgery, ed 2. New York, 2002, Lippincott. 14. Charlick DA, Caborn DN. Alternative soft-tissue graft preparation technique for cruciate ligament reconstruction. Arthroscopy 2000;16: E20.

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Suggested Readings Brand JC Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation: strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. Morgan CD, Caborn D. Anatomic graft fixation using a retrograde biointerference screw for endoscopic anterior cruciate ligament reconstruction: single-bundle and 2-bundle techniques. Tech Orthop 2005;20:297–302.

PART G SOFT-TISSUE GRAFT TIBIAL FIXATION SUB PART I CORTICAL

Fastlok Device for Tibial Fixation of a Tripled or Quadrupled Semitendinosus Autograft for Anterior Cruciate Ligament Reconstruction INTRODUCTION The number of surgeons using hamstring tendons for anterior cruciate ligament (ACL) reconstruction has continuously increased in the past years. As a result, various modifications associated with graft preparation and fixation have been introduced. However, despite these variations in technique, the goal of reconstructing a strong and viable graft with a dependable fixation system remains unaltered. The standard means by which mechanical fixation of hamstring grafts is achieved can either be through direct (interference screws) or indirect (Endobutton [Smith & Nephew, Andover, MA] or screw and washer) techniques. Direct fixation is achieved with an interference screw. With this technique, factors such as divergence, direction of screw placement, the geometry and material composition of the screw, and the graft and tunnel characteristics should be considered to increase the likelihood of a successful outcome.1,2 Indirect fixation techniques, on the other hand, require a linkage material (tape or suture) that would connect the graft tissue to the fixation device. Factors to consider with this technique include: (1) the strength and stiffness of the linkage material to minimize both the potential for elongation of the graft-fixation device construct3–5 and graft-tunnel motion6–8 and (2) the distance of graft fixation from the joint line, which can also influence graft-tunnel motion, especially with early stress on the graft during aggressive rehabilitation. The farther the fixation

site from the joint line, the greater the creep of the graft-fixation device construct.2,5 The technique described here incorporates the use of the Fastlok device (Neoligaments, Leeds, United Kingdom), which is an indirect graft tibial fixation system for hamstring tendon grafts.

41 CHAPTER

Alberto Gobbi Ramces Francisco

SCIENTIFIC RATIONALE A variety of options are available for hamstring tendon graft tibial fixation during ACL reconstruction. These include different types of washers (AO, Washerloc, and Spiked Washer), staples, suture/post, and bioabsorbable screws.9–12 Ideally, the type of fixation chosen should provide the strength and stiffness necessary to withstand failure during cyclical loading, allow the strands to be equally tensioned and compressed into the tibial tunnel wall, and also have the provision for removal when the need arises for revision reconstruction. The use of only the semitendinosus tendon for ACL reconstruction minimizes the possibility of having subsequent flexor weakness from the disruption of the hamstring muscle. With the quadrupled configuration of this graft construct, indirect fixation is usually required because of the total length of the graft achieved.13,14 In the description of the technique that follows, the Fastlok device is combined with a tibial tunnel bone plug that provides additional tunnel compression, which facilitates tendon to bone healing and at the

305

Anterior Cruciate Ligament Reconstruction same time reduces the risk for tunnel widening by limiting the sagittal motion of the graft.15 The Fastlok, on the other hand, offers the ease of using a simple threading technique during application, which helps the graft to retain tension throughout the fixation procedure. In addition, it also minimizes slippage with the staple and buckle fixation, reducing the risk of suture and graft loosening while at the same time maintaining a low profile, which is very important considering the relatively thin soft tissues that cover the involved area of the medial aspect of the proximal tibia.

SURGICAL TECHNIQUE Following the administration of the appropriate anesthesia, the patient is positioned supine on the operating table. A thigh support is placed at the level of the tourniquet cuff while a foot bar is positioned at the end of the table to enable the knee to be fixed at 90 degrees of flexion during surgery while at the same time still allowing free range of motion. Standard prepping and draping of the operative field are performed. During the graft harvest, the tourniquet is kept inflated. Anatomical dissection is carried out to identify the semitendinosus tendon (ST) and separate its accessory limb to avoid premature amputation of the graft. The tendon’s proximal end is detached with the use of an open tendon stripper while its distal end is harvested with an attached tibial bone plug obtained with the aid of an osteotome. Ideally, a graft length of 28 to 30 cm is desired. In the meantime, diagnostic arthroscopy and any associated procedures (e.g., meniscectomy) are performed prior to the preparation of the bone tunnels. The graft is then prepared at the back table, as described in Chapter 16, “Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft.”

Tunnel Preparations and Graft Fixation On the tibia, the tunnel is drilled through the same incision used for tendon harvesting, the length of which depends on the total length of the graft construct, but 2 cm of the graft should remain inserted in the tibia. However, the tibial opening should not be too superior to maintain the desired low profile of the Fastlok device following fixation. The desired entry point for the femoral tunnel is at the 10:30 position for the right knee. The appropriate tunnel depth and diameter are then drilled, and the intraarticular span between the tunnels is measured and recorded. Based on these measurements, the graft is marked with a pen at the level coinciding with the opening of the femoral tunnel. Prior provisions have to be made to consider the length of the Endobutton (8 mm) attached at the end of the 306

A B

D

C

FIG. 41-1 The ends of the polyester tape (C) are threaded through the buckle (A). The buckle is then flipped, followed by the insertion of the two prongs of the staple (B) attached at the end of the impactor (D).

graft if it is to be effectively used as a reference point that indicates the graft is entirely seated in the tunnel with enough space for the Endobutton to be “flipped” into position. Next, the graft is inserted in the tunnels with the standard technique. Proximal fixation is achieved by ensuring that the Endobutton is securely anchored against the posterolateral cortical surface of the femur. At the distal end of the construct, tension on the polyester tapes is maintained in preparation for the placement of the Fastlok fixation device. The polyester tapes are initially passed through the buckle component, which is subsequently flipped. The two prongs of the staple are then threaded through the buckle (Fig. 41-1). Then, with the knee in 30 degrees of flexion, the surgical assistant holds the buckle with a forceps in a flipped position while holding the ends of the tape with the other hand. The Fastlok device is then pressed against the tibia. Once the Fastlok is in position, an impactor is used to drive the staple down in a perpendicular manner. During this step, it is important to maintain the graft’s tension. The protruding portion of the tape is trimmed, and the device is further impacted as needed to achieve a low profile for the device (Fig. 41-2, A–C). Finally, the bone plug obtained from reaming the tibial tunnel is impacted back into the tibia (Fig. 41-3, A, B). Arthroscopic assessment of the graft position during flexion and extension is carried out to make sure that no graft impingement exists.

RESULTS In a biomechanical study conducted to analyze the mechanical properties of linkage systems used in hamstring tendon ACL reconstruction,10 three constructs (5-mm braided polyester [Mersilene], double-loop; 3-mm woven polyester [Orthotape], double-loop; and 3-mm Orthotape,

Fastlok Device for Tibial Fixation of a Tripled or Quadrupled Semitendinosus Autograft for Anterior Cruciate Ligament Reconstruction

41

A

B

C

FIG. 41-2 The staple is positioned perpendicular to the tibial surface with the aid of the impactor (A) while maintaining tension on the graft by pulling on the ends of the polyester tape. Actual appearance of the device prior to final impaction to demonstrate the relation of the tape relative to the device: anteroposterior view (B), lateral view (C).

single-loop—all connected to the Fastlok fixation device in bovine bone sections) were compared using an Instron tensile test machine to document their pull tensile strength, residual tensile strength, and fatigue strength at a loading regimen of 540,000 cycles at 25-Hz frequency. Findings indicate that the double-loop MersileneFastlok construct was weaker than either the single-loop or double-loop Orthotape-Fastlok construct. The mean

failure strength of double-loop Orthotape-Fastlok was 93% higher, and its mean stiffness was 40% greater at failure than the Mersilene-Fastlok. At a 150N load, MersileneFastlok was stiffer, whereas at 300N, Orthotape-Fastlok was stiffer. At 600N, the Mersilene-Fastlok had already failed, whereas the Orthotape-Faslok maintained a stiffness of 128.91 N/m. The mode of failure in all constructs was tape breakage under the Fastlok device. 307

Anterior Cruciate Ligament Reconstruction

FIG. 41-3 The bone plug obtained from the tibia during tibial tunnel preparation (A) is inserted back into the tibial tunnel after the Fastlok device is fixed (B).

Protrusion heights of the constructs after cyclical loading demonstrated no significant increase in height, indicating absence of device pullout or slippage from the bone. The double-loop Orthotape-Fastlok construct had a mean protrusion height of 5.19 mm compared with 4.30 mm for the Mersilene-Fastlok construct. Clinical results reviewed in 190 cases of hamstring ACL reconstruction using the Fastlok device for tibial fixation revealed 17 cases that required subsequent removal of the device. Thirteen cases were secondary to anterior knee pain (over the tibial fixation site) experienced during incidental contact, and four cases were secondary to wound infection (three superficial and one deep). Complaints of pain over the fixation site eventually subsided with removal of the device, and the infected cases were managed successfully with antibiotic administration, with only one case (deep streptococcal infection) requiring further treatment with arthroscopic débridement and lavage.

TROUBLESHOOTING Achieving a stable and reproducible technique for tibial fixation is always a challenge for most surgeons. Although good results have been obtained with the use of conventional staples, certain aspects of both the device and the technique of achieving fixation can be improved. One of the main concerns when using staples for tibial fixation involves the occurrence of slippage. Because this is not immediately apparent at the time of surgery, the surgeon can only do so much in averting this problem. However, in cases in which proper tension is not achieved or the graft is found to be loose after the staple has been placed, the surgeon has no choice but to remove

308

the staple and reapply it with proper tension. To minimize this problem, we recommend the use of a staple device in combination with a buckle (e.g., Fastlok). The addition of this simple component facilitates tensioning and locks the graft in position while the staple is driven down the tibia (see Figs. 41-1 and 41-2). The device can be easily fixed, assuming the surgeon maintains a perpendicular position while driving the Fastlok to the tibia. Concerns regarding the prominence of the device are addressed by allowing sufficient soft tissue coverage over the staple prior to skin closure. Moreover, once the graft has healed, removal of the staple remains an option.

CONCLUSIONS Indirect fixation in quadrupled semitendinosus tendon ACL reconstruction with the use of a Fastlok device combined with a tibial bone plug enable the achievement of good clinical results with a reliable and secure tibial fixation. The profile compared with other staples and washers is lower; however, despite this advantage, we still had an 8% incidence of hardware removal, especially in thin female patients. Therefore we do not suggest the use of this device in this particular group of patients. In contrast, our findings suggest that Fastlok fixation is better suited for high-demand male athletes, with the better clinical results including the degree of knee stability achieved compared with the former group.

References 1. Bickerstaff D. BASK instructional lecture 4: anterior cruciate ligament graft fixation. Knee 2001;8:79–81.

Fastlok Device for Tibial Fixation of a Tripled or Quadrupled Semitendinosus Autograft for Anterior Cruciate Ligament Reconstruction 2. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med 1987;15:225–229. 3. Brand J Jr, Weiler A, Caborn DNM, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 4. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5 year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 5. Ishibashi, Y, Rudy TW, Kim HS, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using robotic testing system. Arthroscopy 1997;13:177–182. 6. Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1997;79A:1556–1576. 7. Gobbi A, Panuncialman I. Quadrupled bone-semitendinosus ACL reconstruction: a prospective clinical investigation in 100 patients. J Orthop Traumatol 2003;3:120–125. 8. Hoher J, Livesay GA, Ma CB, et al. Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation. Knee Surg Sports Traumatol Arthrosc 1999;7:215–219. 9. Brown CH Jr, Sklar JH. Endoscopic anterior cruciate ligament reconstruction using quadrupled hamstring tendons and Endobutton femoral fixation. Tech Orthop 1998;13:281–298. 10. Gobbi A, Mahajan S, Tuy B, et al. Hamstring graft tibial fixation: biomechanical properties of different linkage systems. Knee Surg Sports Traumatol Arthrosc 2002;10:330–334. 11. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue graft. Am J Sports Med 1999;24:35–43.

41

12. Weiler A, Scheffler S, Gockenjau A, et al. Different hamstring tendon graft fixation techniques under incremental loading conditions [abstract]. Arthroscopy 1998;14:425–426. 13. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 14. Gobbi A, Francisco R. Fastlok tibial fixation for hamstring anterior cruciate ligament reconstruction. Tech Orthop 2005;20:274–277. 15. Fu FH, Bennett CH, Ma B, et al. Current trends in anterior cruciate ligament reconstruction. Part II: operative procedures and clinical correlations. Am J Sports Med 2000;28:124–130.

Suggested Readings Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon autograft for anterior cruciate ligament reconstruction: a randomized study with two year follow-up. Am J Sports Med 2001;29:722–728. Höher J, Moller HD, Fu FH. Bone tunnel enlargement after anterior cruciate ligament reconstruction: fact or fiction? Knee Surg Sports Traumatol Arthrosc 1998;6:231–240. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188.

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42 CHAPTER

Chadwick C. Prodromos Aaron Hecker

Whipstitch-Post Tibial Fixation for Anterior Cruciate Ligament Reconstruction Essentially, only three methods are currently in use for gripping anterior cruciate ligament (ACL) grafts so that they may be fixated to bone. These methods are as follows: 1 Friction: Fixation is applied either against cancellous bone by an intratunnel interference screw or on the cortex by a gripping washer such as a WasherLoc, staple, or similar device. 2 Loop: The graft is looped around a post such as a cross-pin or through a fabric loop such as the Endobutton-CL construct. This is generally, but not always, done at the femoral end. 3 Whipstitch: A suture is interwoven into the graft and then tied around a post or loop—the so-called “whipstitch-post fixation” (WSP). WSP was one of the first devised methods of graft fixation, but with the increase in popularity of bone–patellar tendon–bone (BPTB) grafts and interference screws in the 1980s, the WSP became less popular. Hamstrings (HS) were believed to be less stable, and hamstring surgeons emulated BPTB techniques in an effort to increase stability, including the use of interference screws with bone blocks and other friction fixation techniques. This ignores the fact that friction fixation is inherently less suited to the smooth, compressible, viscoelastic soft tissue graft than to the rough-surfaced, rigid BPTB graft. It also ignores the fact that many of the highest-stability results in the literature with soft tissue grafts used WSP

310

tibial fixation. This chapter will present biomechanical and clinical data supporting WSP. It also provides detailed technique and troubleshooting sections.

BIOMECHANICS Elongation and Stiffness The purpose of fixation is to hold the graft without allowing elongation from the fixation site until biological healing has occurred. Elongation can occur from slippage of the fixation device relative to the bone or slippage of the graft relative to the fixation device. Although stiffness has been much considered as an important attribute of ACL graft fixation devices, it is less important than elongation because it only represents the elasticity of the graft–fixation construct prior to the healing of the graft in the tunnel. For BPTB this is roughly 6 weeks. For soft tissue it is 8 to 10 weeks. After this period the stiffness of the fixation device or the extraarticular portion of the graft is no longer part of the load-bearing portion of the structure, which consists only of the intraarticular portion of the graft. In fact, a high-stiffness construct will tend to concentrate mechanical force on the graft–bone interface before graft incorporation has occurred, whereas a low-stiffness construct will dissipate graft strain through elastic deformation of the graft–fixation construct and potentially offer some protection to slippage or elongation at the fixation–bone interface. The WSP method relies on extratunnel

Whipstitch-Post Tibial Fixation for Anterior Cruciate Ligament Reconstruction TABLE 42-1 Graft Elongation as a Function of Tibial Fixation Method: Coleridge and Amis and Prodromos Results Fixation Method

Mean Adjusted Range (mm) Standard Slip (mm)

Deviation (mm)

Intrafix (2)

0.69

0.43–3.72

0.66

WasherLoc (2)

0.88

0.80–3.92

0.86

Delta screw (2)

1.14

0.80–3.92

0.86

Bicortical screw (2) 1.17

0.84–2.44

0.55

RCI screw (2)

1.30

0.76–3.27

0.92

Endobutton (3)

1.13

0.66–1.64

0.32

cortical fixation and would be a lower-stiffness construct than an aperture-fixated construct because it is longer, if all else were equal. However, To et al1 have shown that the increase in stiffness produced by the use of cortical fixation is much greater than the reduction in stiffness from the greater length of the construct. Clinically, grafts usually elongate as a result of cyclical loading, not catastrophic failure. Some of the lowest elongations yet recorded from cyclical loading were published in a recent study of six commonly used devices by Coleridge and Amis2 and are in the range of 1 mm after 1000 cycles. In a recent study we found elongation using WSP fixation to be unsurpassed by any of these fixation devices3,4 (Table 42-1). The standard deviation was also very low, indicating high consistency of the fixation results.

42

CLINICAL RESULTS A recent meta-analysis of all HS and BPTB clinical series7 subdivided HS grafts into subgroups by fixation type. The subgroup with the highest stability rates used an Endobutton on the femur and primarily WSP tibial fixation. Of the six high-stability series with no graft failures, four used WSP fixation.8–11 Finally, the study with the overall highest stability rate also used WSP.8 Recently presented data from a series of five-strand hamstring grafts12,13 that used WSP fixation on both the tibia and femur with mean 8-year follow-up had the highest stability rates yet reported for a semitendinosus/gracilis (ST/Gr) graft.8 It should also be pointed out that these stability rates exceeded those found using BPTB from this same meta-analysis. Morbidity, if the screw is carefully placed, is almost nonexistent. A 0% rate of screw removal due to patient irritation from the cortical screw post has been recently reported in a large series with 2- to 8-year follow-up.11

SURGICAL TECHNIQUE Principal The key to the WSP technique is to maximally tighten the suture weave in the graft before tying the sutures to the post. In this way no significant post-fixation elongation should occur.

Indirect Versus Direct Fixation

Sutures

Direct fixation holds direct purchase on the graft. Examples are interference screws and spiked ligament screw washers. Indirect fixation holds purchase through an intermediary substance. Tibial WSP fixation is in the indirect category, as is the fabric loop of Endobutton fixation. Both methods can be used effectively. However, indirect fixation has the added advantage of being able to accommodate a shorter graft. There is evidence that 15 mm5 or less6 is sufficient graft length in the tunnel to allow satisfactory healing. This is all that is needed for indirect fixation such as the WSP described here. Greater length is required for interference screw fixation to allow sufficient length of graft along the interference screw. Even more length is required if a spiked ligament screw washer is used on the tibial cortex because the graft must be long enough to extend out of the tibial tunnel.

We use the #2 braided nonabsorbable suture. Newer highstrength #2 sutures, such as Fiberwire (Arthrex, Naples, FL) or Ultra-braid (Smith & Nephew, Andover, MA), can also be used. The suture must be colored or striped so that the surgeon can clearly differentiate it from the graft during implantation to avoid knicking or cutting the suture.

Suitable Tibial Screws Many suitable products are available (Fig. 42-1). We use the Smith & Nephew 4.5-mm screw, which does not require a washer. The screw is best inserted with a 2.7-mm drill bit rather than the 2.4-mm bit supplied by the company. It should always be tapped. Most screws are 25 to 35 mm in 311

Anterior Cruciate Ligament Reconstruction Because the screw is inserted just posterior to the old insertion of the semitendinosus at the distal end of the pes anserinus, it is more than far enough from the knee to allow satisfactory magnetic resonance imaging (MRI) of the knee without ferromagnetic artifact.

Whipstitch Implantation Tubularization Conceptually the suture tubularizes the graft. If the graft can be thought of as a sheet (Fig. 42-2), the suture sews the two ends together so that it is essentially folded longitudinally (Fig. 42-3) and then retraces backward, folding it longitudinally again. It is key that the surgeon understands and sees where the suture is going so that he or she does not damage prior placed suture throws with the needle. As previously mentioned, it is imperative that a dyed or striped suture be used. A white suture is difficult to distinguish from the white tendon.

FIG. 42-1 Tibial screws for “whipstitch-post” fixation. A, Smith & Nephew, 4.5 mm, no washer used; B, Linvatec, 6.5 mm, washer mandatory; C, Arthrex 4.5 mm, washer optional.

length. Linvatec makes an excellent 6.5-mm screw that we used for years, which does require a washer. Arthrex makes a bioabsorbable screw that we would not recommend (see later discussion). Arthrex also makes a 4.5-mm screw for use without a washer and a 6.5-mm cancellous screw, which is used with a washer. This last screw, however, is used with a small, 2.5-mm, hexagonal screwdriver. In the past we had problems with screwdriver head breakage due to the smaller hexagonal size relative to the larger screw.

Bioabsorbable or Radiolucent Tibial Screws

FIG. 42-2 The periosteum continuous with the common insertion is held at full width.

Bioabsorbability The tibial screws have not needed to be removed, so there is little benefit to bioabsorbability. Also, recent evidence has shown that most of the supposedly bioabsorbable screws are still intact years after implantation. More important, any bioabsorbable screw will be made of a softer material than metal. The tension of the sutures on the screw is quite high. Any indentation of the screw by the suture, even if only a few millimeters, would be sufficient to compromise stability. Therefore we believe bioabsorbable screws pose unacceptable risk and no significant benefit. Arthrex does make such a screw. We have no experience with it.

Radiolucency We know of no radiolucent tibial post screw except for the bioabsorbable one described in the previous paragraph. 312

FIG. 42-3 Whipstitches are placed to fold the tendon on itself.

Whipstitch-Post Tibial Fixation for Anterior Cruciate Ligament Reconstruction

42

gracilis. These ends are knotted together before passage. Like double sutures can then be tied together after tensioning for each graft.

4ST

FIG. 42-4 With every two throws, the suture is pulled very tightly to eliminate slack as the tendon tubularizes.

Tensioning Of equal importance is that the sutures be maximally tightened after roughly every two throws (Fig. 42-4) so that no further tightening takes place after implantation. This requires the assistant to wrap the free suture end twice around his or her finger so that it will not slip while the surgeon wraps the other end around his or her own finger. They are then pulled in opposite directions, maximally tightening the weave. The force required is great, and if the suture is not wrapped properly it is possible to cut one’s finger on the suture (without cutting the glove). This should not happen in practice if care is taken. When the tightening of the weave is complete, the surgeon and assistant will have a sense of transmitting force directly to each other via the suture because no tightening is occurring within the graft.

Our second most commonly used graft is the 4ST. This is used if the semitendinosus is 50 cm or more in length. The graft is cut in half to make two separate graft limbs. The subsequent whipstitch technique is then identical to that described above for the four-strand semitendinosus/gracilis graft. In the 4ST we begin by overlapping the two free ends of the graft and then whipstitching them together in the same fashion as described earlier for the ST overlapped above with the Gr. For example, if the total length were 30 cm, this would result in a 15-cm double thickness graft. A heavy suture is then looped under the apex of this graft and strong tension applied while the just-implanted whipstitch provides countertension from the other end. The second whipstitch is then interwoven in this folded end of the graft.

3ST/2Gr We use this five-strand graft for knees in which extra strength is required, such as patients with generalized ligamentous laxity, large patients with small tendons, or revisions or chronic ACL tears with stretched-out secondary restraints. Preparation is the same as for 2ST/2Gr except that the extra strand of ST has a #2 whipstitch placed in each end. The wider distal end of the limb has the sutures tied 1  1 around the fabric loop of the Endobutton-CL. The proximal end sutures are tied 1  1 around the tibial screw post.

Tibialis or Peroneus Allograft

Techniques for Specific Grafts 2ST/2Gr The 2ST/2Gr is our most commonly used graft. The common insertion of the ST and Gr is double the width of each tendon individually. This is because at the insertion the ST and Gr are a single tendon for their terminal 1.5 cm or so. In line with this distally is another roughly 1.5 cm of periosteum that is dissected free from the tibia, which serves to prolong this terminal insertion to a length of usually 3 cm. This provides an ideal whipstitch implant tissue. This common distal insertion and periosteal extension is longitudinally cut to make two separate tendons prior to whipstitch insertion. The assistant holds two Adson forceps on the corners of each of the graft ends while the surgeon interweaves the suture, tubularizing it as described previously. The whipstitches from the distal ends and the proximal ends are eventually each tied 2  2 around the tibial post with the graft apex held at the femoral end by the Endobutton-CL loop or a cross-pin. It is helpful to use two different colored sutures for the semitendinosus and for the

For this wider tendon, only one whipstitch is tied in each end. For this reason, it is important that either a newer high-strength #2 braided nonabsorbable suture (as described above) or alternatively a #5 braided nonabsorbable suture is used. This is because only half the number of sutures are available to withstand the tensile stresses of this two-strand graft compared to the number of suture strands available for the four-strand hamstring grafts.

Quadriceps Tendon Autograft or Tendo-Achilles Allograft The technique is the same for both grafts. In both cases we would recommend the graft without bone, although if desired, bone can be left attached at one end and interference fixation used on that end in the femur. The terminal 3 cm of each end is then longitudinally split, creating four ends. Whipstitches are then placed in each so that they can be tied 2  2 around a post placed in the tibia and another on the femur. Alternatively the femoral sutures can be tied around the fabric loop of an Endobutton-CL. 313

Anterior Cruciate Ligament Reconstruction

Trimming Tendon Grafts

Screw Insertion

Tendon grafts should be cleaned of all nontendinosus tissue before whipstitch implantation. However, after the whipstitches are put in, the surgeon should again trim off loose pieces of tissue with an Adson forceps from the tendon ends, thereby further debulking them. It is important to debulk the tendon ends in this fashion. The whipstitches add bulk such that the tibial end is usually 8 to 10 mm, most commonly 9 mm. If the ends are not debulked, the graft can potentially require an 11-mm tunnel. The sizing of the graft can also help to streamline the ends and shrink them by 0.5 mm or so.

Screw Insertion Location

Sizing the Grafts It should be noted that the femoral looped end is almost always smaller than the tibial end if whipstitches are used on the tibial end. Typically the femoral end will be 1 mm smaller, often 8 mm for the femoral tunnel and 9 mm for the tibial tunnel. The femoral tunnel for the 2ST/2Gr can be as small as 7 mm. If the graft is sized before whipstitch implantation, 1 mm should be added to allow for the bulk of the suture.

Tying the Whipstitches The 2  2 tying routinely done must be performed under strong tension. The following procedure is performed first for one graft limb and then repeated for the second limb. First the suture ends are pulled down, two on either side of the previously inserted tibial screw post. The post is inserted so that the threads are implanted in bone but the short smooth shank area is exposed. The sutures are then crossed around the smooth shank and pulled up. Very strong tension is maintained while the assistant cycles the knee moderately slowly three times from 0 degrees to full-flexion range of motion. We tie the sutures with the knee at 30 degrees flexion with the patient’s foot supported on the surgeon’s anterior thigh closest to the table. The tension in the graft comes from the surgeon pulling up on the sutures, crossed below the smooth screw shank, while the assistant pushes down on the top of the thigh to provide countertension. The assistant uses the other hand to control the patient’s ankle. Seven or eight very firm square throws are tied. Some feel the sutures should not be tied with the knee at 30 degrees flexion lest the knee become too tight, “constrained,” or “captured.” However, we have never had a significant flexion contracture using this technique with a soft tissue graft and believe it is important not to under-tension and thus leave residual laxity. Final screw tightening is then carried out. 314

The screw should be inserted just posterior to the former insertion of the harvested ST along the medial tibial shaft just anterior to the tibial attachment of the medial collateral ligament.

Unicortical Implantation The screw should be inserted unicortically and not bicortically for four reasons, as follows: 1 The screw is eventually tightened down nearly flush with the bone but cannot be tightened enough initially to allow the tip to engage a hole in the opposite cortex for bicortical use because enough of the smooth shank must be left out of the tibial cortex to allow room for suture tying. After tying, the screw is further tightened. However, the tying of the sutures is done under such strong tension that the screw will often toggle slightly in the tunnel before settling. This is not visually apparent, but the screw can be thereby redirected enough that the tip will not find the predrilled hole in the far cortex. In some cases this will prevent final tightening, resulting in the screw sitting proud where it can be a later irritant to the patient. If the tibial tunnel is inserted unicortically the length will only be measured to the opposite cortex. Then when the screw is tightened, the tip of the screw will at most meet but not abut or be stopped by the opposite tibial posterior cortex. This allows the screw to sit nearly flush against the tibial cortex, where it will not irritate the patient. 2 Neurovascular structures are located near the exit point of the tibial screw.15,16 Unicortical use avoids neurovascular risk without loss of satisfactory purchase. 3 These are cancellous screws, which are not meant to be inserted bicortically. Such a screw is potentially irremovable if the tip is buried in cortical bone. 4 It is not necessary to insert the screw bicortically. We have used it unicortically for many years with excellent stability results.11

Screw Tightening The low-profile tibial screw post has been previously inserted so that the threads are interosseous and only the smooth shank remains exposed to prevent the sutures from being cut on the threads. After tying, the screw should be further tightened. A “dead man’s” angle of 10 degrees or so is desirable, with the screw inserted so that the tip points slightly proximally and the head will wind up slightly distal. In this way the sutures cannot ride over the head of the screw. The strong tension on the sutures also prevents this. Because the screw enters slightly obliquely and because the sutures and knot have some bulk, the screw will not sit flush against bone but rather will sit

Whipstitch-Post Tibial Fixation for Anterior Cruciate Ligament Reconstruction a few millimeters proud (i.e., the width of the compressed suture and knot). We have not seen this to be a clinical problem, although the screw may be palpable if patients feel for it. We have never had a patient request that a screw be removed. One should not attempt to flatten the screw against the tibia by repeated twisting because this can loosen its purchase. It should not be hit with a mallet to avoid potential tibia fracture.

TROUBLESHOOTING 1 What if the graft is loose after the WSP procedure is finished? We have had this happen once in a large patient in whom adequate tension was not maintained on the sutures during tying. The screw was positioned too high up in the deep but short incision to allow room for satisfactory upward tension on the sutures by the surgeon. This was discovered on final arthroscopic inspection of the graft after tying. The screw was unscrewed, using a hemostat (pushing, not gripping) to keep the sutures held tightly upward on the smooth shank to avoid trauma on the sharp threads. The screw was then pulled more distally until strong tension was felt (a distance of about 5 mm), a new tibial hole was drilled with a good bone bridge separating it from the prior hole, and the screw was inserted in this more distal location. Excellent graft tension and stability resulted. 2 What if the whipstitch is damaged during the suture interweaving? If there is any question of the suture being damaged, it must be removed and the process begun again. We have done this on a few occasions with no ill effects. The suture must be carefully removed. The graft is strong enough to tolerate a new whipstitch being put in. It must be carefully tightened again during implantation. 3 What if the graft is so long that it abuts the screw, not allowing room to tension the sutures? We have not had this happen. If it were to happen we would recommend withdrawing the screw and inserting it more distally. By planning graft length in advance, this should be easily avoided.

CONCLUSIONS 1 Stability: WSP fixation produces unsurpassed stability. 2 Morbidity: Morbidity is virtually nonexistent. The incidence of screw irritation and removal of the screw is very low if it is properly placed (0 in our series). 3 Unicortical screw placement: For several reasons, as cited previously, the screw should be placed unicortically. 4 Metallic screws: Metallic screws are recommended. They do not interfere with MRIs because they are remote from

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the knee joint on the metaphysis. Bioabsorbable screws are not recommended due to their softness. 5 Use with a short graft: Because this is indirect fixation, it can be used with a shorter graft or 4ST or quadriceps tendon. The literature supports a minimum of 15 mm of graft, possibly less in the tunnel for healing. More is required for interference or other friction fixation. 6 Ease of use: The whipstitches must be meticulously placed and the weave maximally tightened, but the technique is straightforward and easy to learn for surgeons not familiar with it.

References 1. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 2. Coleridge SD, Amis AA. A comparison of five tibial-fixation systems in hamstring-graft anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:391–397. 3. Prodromos CC, Hecker A. Unpublished data. 4. Harvey AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction. Knee 2003;10:92–102. 5. Zantop T, Brucker P, Bell K, et al. The effect of tunnel-graft length on the primary and secondary stability in ACL reconstruction: a study in a goat model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 6. Yamazaki S, Yasuda K, Tomita F, et al. The effect of intraosseous graft length on tendon-bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 2006;14:1086–1093. 7. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 8. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 9. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 10. Hamada M, Shino K, Horibe S, et al. Preoperative anterior knee laxity did not influence postoperative stability restored by anterior cruciate ligament reconstruction. Arthroscopy 2000;16:477–482. 11. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 12. Prodromos CC, Joyce BT. Five-strand hamstring ACL reconstruction: a new technique with better long-term stability than four-strand. Presented at the 2006 meeting of the Arthroscopy Association of North America, Hollywood, FL, May, 2006. 13. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at symposium at the 2006 of the American Academy of Orthopaedic Surgeons, Chicago, March, 2006. 14. Prodromos CC. Unpublished data. 15. Post WR, King SS. Neurovascular risk of bicortical tibial drilling for screw and spiked washer fixation of soft-tissue anterior cruciate ligament graft. Arthroscopy 2001;17:244–247. 16. Curran TA, Sekiya JK, Gibbs AE, et al. Two techniques for anterior cruciate ligament tibial fixation with a bicortical screw: an in vitro study of neurovascular risk. Am J Orthop 2006;35:261–264.

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Stephen M. Howell

WasherLoc and Bone Dowel Tibial Fixation of a Soft-Tissue Graft INTRODUCTION The fixation of a soft-tissue anterior cruciate ligament (ACL) graft is more challenging than a bone–patellar tendon–bone (BPTB) graft because the tendon heals slower to a bone tunnel and the fixation is stressed earlier and more vigorously. Slower healing coupled with early and more vigorous stress at the site of fixation can cause slippage and loss of stability with a soft-tissue ACL graft that might otherwise not occur with a BPTB graft. This chapter focuses on the use of the WasherLoc and bone dowel to fix a soft-tissue ACL graft to the tibia. The WasherLoc and bone dowel is a simple, lowprofile fixation technique that promotes early tendon tunnel healing, resists slippage under cyclical load and exercise, and prevents tunnel widening, which simplifies revision surgery.

WASHERLOC AND BONE DOWEL SURGICAL TECHNIQUE The superior clinical and biomechanical performance of the WasherLoc and bone dowel during aggressive rehabilitation and testing in the laboratory has been extensively documented since the technique was introduced in 1997.1–13 The WasherLoc is a multi-spiked washer with four long peripheral spikes that engage cortical bone and multiple shorter spikes that purchase the soft-tissue graft (Fig. 43-1). The WasherLoc

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comes in two lengths (long and standard) and three diameters (14, 16, and 18 mm). The preferred fixation for a 9- to 10-mm diameter soft-tissue graft is the 18-mm-long spike WasherLoc; for a 7- to 8-mm diameter graft, the 16-mm long spike WasherLoc. The WasherLoc is seated in a counterbore inside the distal end of the tibial tunnel. The counterbore recesses the WasherLoc below the cortical surface, which eliminates hardware irritation of the overlying skin (Fig. 43-2).9 A self-tapping, cancellous screw compresses the WasherLoc and soft-tissue graft against the back wall of the tibial tunnel. The tip of the screw engages the lateral tibial cortex, which avoids any damage to the more posterior neurovascular structures. The portion of the tunnel anterior to the soft-tissue graft is dilated, and the bone dowel is compacted into the tunnel. The following is a detailed description of the surgical technique with pertinent illustrations.

Harvest a Bone Dowel from the Tibial Tunnel Remove the cortex overlying the distal end of the tibial tunnel. Choose a cannulated reamer that matches the diameter of the soft-tissue ACL graft, and ream over the tibial tunnel guidewire. Slide the calibrated plunger over the tibial guidewire. Impact an 8-mm bone dowel harvester over the plunger and guidewire to the subchondral bone (Fig. 43-3). Rotate

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fibula, and impact the awl. Insert the counterbore into the awl hole, and orient the counterbore so that it is parallel to the posterior wall of the tibial tunnel and oblique to the anterior tibial cortex. Remove a small amount of bone from the anterior tibial cortex until the counterbore is flush with the back wall of the tibial tunnel (Fig. 43-4).

Impact the WasherLoc Long spike

Standard spike

FIG. 43-1 The WasherLoc is a low-profile washer with four long peripheral spikes and multiple short central spikes. The long peripheral spikes engage cortical bone and contain the soft-tissue anterior cruciate ligament (ACL) graft under the washer. The multiple shorter spikes purchase the soft-tissue graft.

the bone dowel harvester several times clockwise and counterclockwise to break off the cylindrical bone. Remove the bone dowel and harvester. If the guidewire is removed with the bone dowel, then insert an 8-mm reamer into the tibial tunnel and rethread the guidewire through the cannulation in the reamer. Finish reaming the tibial tunnel.

Drill the Counter Bore Use electrocautery and a ronguer to remove a small section of the superficial layer of the medial collateral ligament (MCL) that overlies the cortical opening of the tibial tunnel. Insert the counterbore guide into the tibial tunnel until the vertical sleeve abuts against the distal end of the anterior edge of the tibial tunnel. Point the vertical sleeve at the

Position the knee in full extension. Thread the awl into the drill sleeve and the drill sleeve into the WasherLoc. Tension the soft-tissue graft. Rotate the flat edge of the WasherLoc distal, place half of the soft-tissue ACL graft on each side of the awl, insert the awl in the hole, and direct the tip of the awl toward the fibula. Impact the WasherLoc into the back wall of the tibial tunnel until it is fully seated (Fig. 43-5).

Insert the Self-Tapping, Cancellous Compression Screw Remove the awl, insert a 3.2-mm diameter drill into the drill sleeve, aim toward the fibula, and drill through the lateral cortex of the tibia. Measure the length of the drill hole, and insert the self-tapping, cancellous compression screw until it fully engages the lateral cortex of the tibia.

Dilate the Tibial Tunnel Confirm that stability has been restored to the knee and the tension in the ACL graft is correct. Place the tip of the

FIG. 43-2 The correct orientation of the WasherLoc is perpendicular to the back wall of the tibial tunnel. The correct orientation of the self-tapping, cancellous compression screw is toward the fibula, which avoids damage to the neurovascular structures that are more posterior. The tip of the screw purchases the lateral tibial cortex. The bone dowel fills the anterior and medial tibial tunnel, causing the narrowing seen in the distal half of the tibial tunnel on the anteroposterior and lateral view.

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FIG. 43-3 An 8-mm diameter bone dowel harvester is driven over a tibial guidewire to the level of the subchondral bone. The harvester is rotated several times to break the bone dowel away from the subchondral bone. The typical length of the bone dowel is 20 to 30 mm.

tapered dilator between the anterior surface of the softtissue graft and tibial tunnel (Fig. 43-6). Gently impact the dilator to the level of the joint line, which is typically 25 mm.

Compact the Bone Dowel Stuff any loose bone reamings and wallplasty fragments into the tibial tunnel, and compact the bone with a 7 or 8 impingement rod. Place the plastic cover on the sharp tip of the

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bone dowel harvester, and drive the bone dowel into the tibial tunnel (Fig. 43-7).

Promoting Tendon–Tunnel Healing of a Soft-Tissue Anterior Cruciate Ligament Graft Healing of a soft-tissue ACL graft14 is a greater concern than that of a BPTB graft because a tendon graft heals slower than a bone plug during the first 6 weeks of implantation.15 Healing is more of a problem in the tibia than in

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43

the femur because the marrow is filled with more fat16 and the bone is softer.17 Therefore a soft-tissue graft requires better fixation technique than a BPTB graft,15 especially in the tibia.16 The consequence of not addressing the slow tendon–tunnel healing is slippage during early rehabilitation.18 Slippage is more likely with a soft tissue ACL graft than with a BPTB graft because there is less pain early on.19

Strategies That Promote Tendon–Tunnel Healing One strategy for promoting tendon–tunnel healing is the use of a long, snug tunnel (Fig. 43-8). The healing of a tendon graft is stronger and stiffer when the tunnel is lengthened and the fit between the tendon and tunnel wall is snug.20 Lengthening the tunnel requires placement of the fixation device at the end of the tunnel and not inside (intratunnel device).12 Compaction of a bone dowel into the tibial tunnel along side a soft-tendon graft increases the snugness of fit by filling gaps between the tendon and tunnel wall.21,22 A second strategy for promoting healing is to allow circumferential and avoid one-sided healing between the tendon and tunnel wall (see Fig. 43-8). The healing of a

Aim toward fibula

FIG. 43-4 The counterbore is oriented parallel to the back wall of the tibial tunnel and is aimed toward the fibula. The purpose of the counterbore is to recess the WasherLoc inside the tibial tunnel to avoid irritating the overlying soft tissues.

A

B

FIG. 43-5 The awl (A) is threaded into the drill sleeve (B), which is threaded into the WasherLoc. Half of the graft is placed on either side of the awl. The WasherLoc is oriented parallel to the back wall of the tibial tunnel and is aimed toward the fibula.

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Cone-shaped dilator

might also benefit healing. Autogenous cancellous bone has viable osteoblasts that may initiate, regulate, and accelerate the ingrowth of bone into the tendon. The use of the WasherLoc at the end of the tibial tunnel with compaction of bone dowel fulfills these criteria for promoting tendon– tunnel healing by providing a long, snug tunnel; circumferential healing; and the addition of a biologically active substance.

WASHERLOC RESISTS SLIPPAGE UNDER CYCLICAL LOAD

FIG. 43-6 The cone-shaped dilator is inserted anterior to the soft tissue anterior cruciate ligament (ACL) graft and is impacted 25 mm into the tibial tunnel. The cone-shaped space prevents the cylindrical-shaped bone dowel from being driven into the joint.

tendon graft is stronger and stiffer when the tendon heals to the tunnel circumferentially and is not one-sided. Circumferential healing requires placement of the fixation device at the end of the tunnel so that the entire surface area of the tunnel can heal to the graft.12 One-sided healing occurs with intratunnel devices such as the interference screw.23 The interference screw “interferes” and slows tendon–tunnel healing because the screw prevents one side of the tendon from healing to the graft.12 A third strategy is to surround the tendon graft with a biologically active substance. Healing of a tendon is accelerated and stronger when a biologically active substance is inserted in the tunnel with the graft. Wrapping periosteum around the graft accelerates the healing process of a tendon in a bone tunnel and leads to better biomechanical fixation in a shorter period of time.24 Adding bone morphogenetic protein accelerates the healing process when a tendon graft is transplanted into a bone tunnel.25 The acceleration of healing by periosteum and bone morphogenetic protein suggests that compaction of autogenous bone into the tunnel

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Several biomechanical studies have shown that the WasherLoc has superior resistance to slippage, higher stiffness, and higher strength than other soft tissue tibial fixations.2,3,4,6–9,11–13 When studies are performed using human bone, the WasherLoc slips less, is stiffer, and stronger than interference screw, double staples, soft tissue washer and screw, and sutures tied to a post.9 Although there has been no head-to-head comparison of the IntraFix versus the WasherLoc in human bone, the IntraFix has been shown to slip more under cyclical load than the interference screw,26 which indicates that the IntraFix slips substantially more than the WasherLoc. Cyclical testing simulating 6 weeks of normal walking showed that the slippage of a two-strand soft tissue graft fixed with a WasherLoc was less than 0.6 mm, which is clinically imperceptible (Fig. 43-9). The fixation site was loaded 225,000 times from 0N to 170N to simulate the predicted number of steps in 6 weeks of normal walking and the load in the ACL during normal gait.13 The slippage resistance of the WasherLoc is consistent with clinical results that showed excellent anterior stability with use of brace-free, aggressive rehabilitation and early return to sport at 4 to 6 months.1,5

BONE DOWEL LIMITS TUNNEL WIDENING AT 1 TO 2 YEARS Tunnel expansion in ACL reconstruction is greater with a hamstring autograft than with a BPTB autograft27–29 and occurs with a variety of hamstring fixation devices.28–32 The clinical consequences of the common phenomenon of tunnel expansion are being defined; however, tunnel expansion can complicate revision surgery.33,34 Therefore a technique for fixing a hamstring graft to the tibia that limits tunnel expansion to the cross-sectional area of the reamer might have a clinical benefit by simplifying revision surgery.

WasherLoc and Bone Dowel Tibial Fixation of a Soft-Tissue Graft

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FIG. 43-7 The plastic sleeve is placed over the sharp tip of the bone dowel harvester and inserted into the dilated opening. The bone dowel is compacted into the tibial tunnel and anterior to the soft tissue anterior cruciate ligament (ACL) graft.

FIG. 43-8 Fixation of a soft tissue anterior cruciate ligament (ACL) graft in the tibia is problematic because the cancellous bone is softer and more filled with fat than the femur. The use of a WasherLoc and bone dowel promotes tendon–tunnel healing by providing a long, snug tunnel; circumferential healing (arrows); and the addition of a biologically active substance (A). The use of an intratunnel device such as an interference screw or IntraFix retards tendon–tunnel healing by allowing only one-sided healing between the tendon and tunnel wall (B).

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WasherLoc

G1

T1 G4

T3

T

T5

T4 T6 T2 Proximal end of tibia G2

G3

Cross-section R

2.5-mm post

Aluminum support

FIG. 43-9 Slippage of a two-strand soft tissue anterior cruciate ligament (ACL) graft fixed to the tibia with a WasherLoc was measured using roentgen stereophotogrammetric analysis. The site of fixation was loaded from 0N to 170N for 225,000 cycles, which simulated the loading of the ACL in 6 weeks of normal walking. The slippage was less than 0.6 mm, which is clinically imperceptible and justifies the use of the WasherLoc with brace-free, aggressive rehabilitation and early return to sport at 4 months.

In an in vivo study, a bone dowel averaging 23 mm in length and 7 mm in diameter was harvested from the tibial tunnel in 10 subjects undergoing hamstring ACL reconstruction. The cross-sectional area of the tibial tunnel was calculated on the day of surgery, 4 months, and 1 to 2 years postoperatively from computed tomography scans. The bone dowel reduced the cross-sectional area of the tunnel on the day of surgery and limited tunnel expansion to that of the crosssectional area of the reamer at 4 months and 1 to 2 years (Fig. 43-10). Ninety percent of the subjects treated with a bone dowel had little to no tunnel expansion at 1 to 2 years. The limitation of tunnel expansion to that of the cross-sectional area of the reamer has not been shown with other tibial fixation techniques. Limiting tunnel expansion to that of the cross-sectional area of the reamer should simplify revision surgery.10 322

FIG. 43-10 A computed tomography scan of the bone dowel in the tibial tunnel alongside a double-looped hamstring graft (blue) is shown postoperatively and at 2 years. The bone dowel indents the tibial tunnel, reducing and changing the shape of the space occupied by the anterior cruciate ligament (ACL) graft from round to a smaller crescent shape. Although the tunnel widens somewhat after 2 years, the cross-sectional area of the tunnel at 2 years was no larger than the cross-sectional area of the reamer used to drill the tunnel. The bone dowel limits tunnel widening to that of the reamer at 2 years by shrinking the tunnel cross-sectional area on the day of surgery. (From Matsumoto A, Howell SM. Time related changes in the cross-sectional area of the tibial tunnel after compaction of an autograft bone dowel alongside a hamstring graft. Arthroscopy. In Press.)

CONCLUSION This chapter provides scientific documentation that the WasherLoc and bone dowel meet all the challenges of fixing a soft tissue ACL graft to the tibia. Fixation at the end of the tunnel and the compaction of the bone dowel allow circumferential tendon–tunnel healing and increase the snugness of fit, which solves the problem of a soft tissue ACL graft healing slower than a BPTB graft. Mechanical fixation of the WasherLoc in cortical bone and gripping of the soft tissue graft with multiple spikes solve the problem of the site of fixation being more vigorously stressed than with a BPTB graft. The compaction of the bone dowel prevents tunnel widening, which simplifies revision surgery. The use of the WasherLoc and bone dowel is a simple, low-profile

WasherLoc and Bone Dowel Tibial Fixation of a Soft-Tissue Graft fixation technique that promotes early tendon–tunnel healing, resists slippage under cyclical load and exercise, and is well suited for brace-free, aggressive rehabilitation of patients reconstructed with a soft tissue ACL graft.

References 1. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. A prospective, randomized clinical trial. J Bone Joint Surg 2004;86A:2143–2155. 2. Bailey SB, Grover DM, Howell SM, et al. Foam-reinforced elderly human tibia approximates young human tibia better than porcine tibia: A study of the structural properties of three soft-tissue fixation devices. Am J Sports Med 2004;32:755–764. 3. Coleridge SD, Amis AA. A comparison of five tibial-fixation systems in hamstring-graft anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:391–397. 4. Grover DM, Howell SM, Hull ML. Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices. J Bone Joint Surg 2005;87A:381–390. 5. Howell SM, Gittins ME, Gottlieb JE, et al. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. 6. Howell SM, Roos P, Hull ML. Compaction of a bone dowel in the tibial tunnel improves the fixation stiffness of a soft tissue anterior cruciate ligament graft: an in vitro study in calf tibia. Am J Sports Med 2005;33:719–725. 7. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 8. Kudo T, Tohyama H, Minami A, et al. The effect of cyclic loading on the biomechanical characteristics of the femur-graft-tibia complex after anterior cruciate ligament reconstruction using Bone Mulch screw/WasherLoc fixation. Clin Biomech (Bristol, Avon) 2005;20:414–420. 9. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 10. Matsumoto A, Howell SM. Time related changes in the cross-sectional area of the tibial tunnel after compaction of an autograft bone dowel alongside a hamstring graft. Arthroscopy 2006;22:855–860. 11. Roos PJ, Hull ML, Howell SM. Lengthening of double-looped tendon graft constructs in three regions after cyclic loading: a study using Roentgen stereophotogrammetric analysis. J Orthop Res 2004;22:839–846. 12. Singhatat W, Lawhorn KW, Howell SM, et al. How four weeks of implantation affect the strength and stiffness of a tendon graft in a bone tunnel: a study of two fixation devices in an extraarticular model in ovine. Am J Sports Med 2002;30:506–513. 13. Smith CK, Hull ML, Howell SM. Lengthening of a single-loop tibialis tendon graft construct after cyclic loading: a study using roentgen stereophotogrammetric analysis. J Biomech Eng 2006;128:437–442. 14. Chen CH, Chen WJ, Shih CH, et al. Enveloping the tendon graft with periosteum to enhance tendon-bone healing in a bone tunnel: a biomechanical and histologic study in rabbits. Arthroscopy 2003;19:290–296. 15. Tomita F, Yasuda K, Mikami S, et al. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bonepatellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy 2001;17:461–476. 16. Grassman SR, McDonald DB, Thornton GM, et al. Early healing processes of free tendon grafts within bone tunnels is bone-specific: a morphological study in a rabbit model. Knee 2002;9:21–26.

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17. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament: a comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 18. Giurea M, Zorilla P, Amis AA, et al. Comparative pull-out and cyclic-loading strength tests of anchorage of hamstring tendon grafts in anterior cruciate ligament reconstruction. Am J Sports Med 1999;27:621–625. 19. Feller JA, Webster KE, Gavin B. Early post-operative morbidity following anterior cruciate ligament reconstruction: patellar tendon versus hamstring graft. Knee Surg Sports Traumatol Arthrosc 2001;9:260–266. 20. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 21. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 22. Wallace MP, Howell SM, Hull ML. In vivo tensile behavior of a four-bundle hamstring graft as a replacement for the anterior cruciate ligament. J Orthop Res 1997;15:539–545. 23. Weiler A, Hoffmann RF, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135. 24. Kyung HS, Kim SY, Oh CW, et al. Tendon-to-bone tunnel healing in a rabbit model: the effect of periosteum augmentation at the tendon-tobone interface. Knee Surg Sports Traumatol Arthrosc 2003;11:9–15. 25. Rodeo SA, Suzuki K, Deng XH, et al. Use of recombinant human bone morphogenetic protein-2 to enhance tendon healing in a bone tunnel. Am J Sports Med 1999;27:476–488. 26. Caborn DN, Brand JC Jr, Nyland J, et al. A biomechanical comparison of initial soft tissue tibial fixation devices: the Intrafix versus a tapered 35-mm bioabsorbable interference screw. Am J Sports Med 2004;32:956–961. 27. Clatworthy MG, Annear P, Bulow JU, et al. Tunnel widening in anterior cruciate ligament reconstruction: a prospective evaluation of hamstring and patella tendon grafts. Knee Surg Sports Traumatol Arthrosc 1999;7:138–145. 28. L’Insalata JC, Klatt B, Fu FH, et al. Tunnel expansion following anterior cruciate ligament reconstruction: a comparison of hamstring and patellar tendon autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234–238. 29. Webster KE, Feller JA, Hameister KA. Bone tunnel enlargement following anterior cruciate ligament reconstruction: a randomized comparison of hamstring and patellar tendon grafts with 2-year followup. Knee Surg Sports Traumatol Arthrosc 2001;9:86–91. 30. Buck DC, Simonian PT, Larson RV, et al. Timeline of tibial tunnel expansion after single-incision hamstring anterior cruciate ligament reconstruction. Arthroscopy 2004;20:34–36. 31. Buelow JU, Siebold R, Ellermann A. A prospective evaluation of tunnel enlargement in anterior cruciate ligament reconstruction with hamstrings: extracortical versus anatomical fixation. Knee Surg Sports Traumatol Arthrosc 2002;10:80–85. 32. Simonian PT, Levine RE, Wright TM, et al. Response of hamstring and patellar tendon grafts for anterior cruciate ligament reconstruction during cyclic tensile loading. Am J Knee Surg 2000;13:8–12. 33. Bach BR Jr. Revision anterior cruciate ligament surgery. Arthroscopy 2003;19:14–29. 34. Fink C, Zapp M, Benedetto KP, et al. Tibial tunnel enlargement following anterior cruciate ligament reconstruction with patellar tendon autograft. Arthroscopy 2001;17:138–143.

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44 CHAPTER

Konsei Shino

Double-Spike Plate: Cortical Fixation Device Enabling Graft Fixation Under Optional Tension BACKGROUND AND BASIC CONCEPT The pullout technique by tying sutures around a screw post or over a button is commonly used as a stand-alone fixation or as an augmentation for interference screw fixation into a tibial bone tunnel in the final stage of anterior cruciate ligament (ACL) or other ligament reconstruction. As the step of tensioning cannot be separated from that of fixation in this technique, the following problems have remained unsolved: loosening or breakage of the sutures while tying sutures around a post1 and difficulty in correctly controlling the tension to the graft.2 In order to solve these problems, a fixation device, the double-spike plate (DSP) (Ref. 020A-004, MEIRA Corp., Nagoya, Aichi, Japan) was developed to separate the step of tensioning from that of fixation.1 This device is currently commercially-sold only in Japan by Smith & Nephew Japan but will be shortly launched into the world market.

SPECIFICATIONS AND INSTRUMENTS FOR USE The DSP is a small plate made of titanium alloy with three holes and two spikes on the reverse side (Fig. 44-1). There are two sizes available: the standard DSP for big knee or single tunnel reconstruction (11 mm wide  18 mm long  1.5 mm thick with two spikes of 5.5 mm length) to be used with a 6.5-mm screw and the small DSP for a small knee or double-bundle procedure (8.5 mm wide  13.8 mm long  1.5 mm thick 324

with spikes of 4.2 mm length) to be used with a 5-mm screw (see Fig. 44-1). The impactor is available for securely hammering base spikes into the cortical bone (Fig. 44-2). The centering drill guide is also available for creating a screw hole.

RATIONALE FOR MAINTAINING THE TENSION DURING GRAFT FIXATION TO THE TIBIA If the top end of the DSP closely keeps in close contact with the tibial cortex without movement, the DSP should show hinge motion around its top in the sagittal plain while its spikes are hammered into the tibia (Fig. 44-3). Thus the prehammering tension of the graft suture that has already been tied to the top hole could be assumed to be equal to its post-hammering tension. Although there is an instant increase of the tension due to minimal distal movement of the plate when the base spikes are hammered into the cortex, the tension goes down almost to the predetermined level after load relaxation for a minute or two (Fig. 44-4).

IN VITRO BIOMECHANICAL DATA USING PORCINE TIBIAE AND BOVINE FLEXOR TENDONS Ten fresh frozen porcine tibias, in which 8-mm drill holes had been created from just medial to the tibial tubercle to the attachment of the ACL, were rigidly fixed to an Instron tension

Double-Spike Plate: Cortical Fixation Device Enabling Graft Fixation Under Optional Tension

44

Sutures connecting graft to DSP

Fixed to a load

Tension with a suture Tibial tunnel

A FIG. 44-1 Double-spike plate (DSP) for graft fixation under an optional tension. The standard-sized DSP is a 1.5-mm-thick, 18-mm-long, 11-mm-wide, small plate made of titanium alloy with three holes and two spikes of 5.5 mm length on the reverse side. 1, Top hole for connecting the double-spike plate (DSP) to the free ends of a graft by tying sutures; 2, central hole to insert a screw for completing the fixation; 3, bottom hole for tensioning the suture; 4, spikes for temporal fixation without loss of tension.

B

FIG. 44-2 The tip of the impactor for securely hammering the base spikes into the bone.

analyzer. Using bovine tendons, a quadrupled graft consisting of two double-looped tendons of 7 cm in length and 8 mm in diameter were prepared with baseball glove stitching using #3 braided polyester sutures at the distal end of the graft. The graft was passed through the drill hole, and its proximal loop ends were connected to a load cell for monitoring tension (see Fig. 44-3, A). The graft sutures were tied to a standard-sized DSP through its top hole, pretensioned at 49N or 98N for 5 minutes, and temporarily fixed to the tibia by hammering the spikes on its reverse side to the anterior surface of the tibia (see Fig. 44-3, B). Permanent fixation was achieved by inserting a 6.5-mm cancellous screw (see Fig. 44-3, C). Although the graft tension instantly increased to 69N  11N (mean  standard

C FIG. 44-3 Three steps of graft fixation under tension with double-spike plate (DSP) after completion of fixing the graft on the other end. A, A certain amount of tension is applied to the graft with a suture through the bottom hole after the graft’s distal sutures are tied to the top hole. B, Temporary fixation is achieved by hammering the spikes into the bone with the plate’s top end kept closely in touch with the bony surface. C, The final fixation is accomplished by inserting a screw through the center hole.

deviation) (range 53–80N) or 133N  14N (range 121– 157N) during hammering of the spikes, it settled to 49N  1N (range 37–63N) or 100N  7N (range 88–107N) at 5 minutes after completing the fixation. The same experiment on four porcine tibias was performed with a small-sized DSP under the initial tension of 49N, followed by final fixation using a 5.0-mm 325

Anterior Cruciate Ligament Reconstruction 80

(1) (2)

70

Graft tension (N)

60 50 40 30 20 10 0 0

50

100

150

200

250

300

350

400

Time (sec) FIG. 44-4 Note that graft tension instantly increased up to 73N and gradually settled down to 52N over time. 1, Hammering the spikes; 2, inserting a screw.

FIG. 44-5 Fixation of two- or three-bundle graft using double-spike plates (DSP) under tension after femoral fixation. Note the tensioners installed to the half-shell tensioning boot, which is bandage-fixed to the calf.

cancellous screw. Although the graft tension instantly increased to 53N  6N (range 48–63N) during hammering of the spikes, it settled to 45N  7N (range 37–53N) after completing the fixation (see Fig. 44-4). Considering that porcine tibias are softer than those of young active candidates for ACL reconstruction, these results suggest that the graft tension can be adjusted at the time of its fixation to the tibia with the DSP.

EASY, SECURE, AND CONSISTENT PULLOUT ANTERIOR CRUCIATE LIGAMENT GRAFT FIXATION WITH DOUBLE-SPIKE PLATES First, the periosteum should be removed from the bony surface where installation of the plates is planned. After femoral side fixation is completed, the sutures placed to the graft’s distal end are tied to the top hole of DSP. The tensioning sutures distally connected to the DSP are tied to the tensioners mounted to a metal shell boot that has already been fixed to the tibia with bandage (Fig. 44-5). It is our current choice to apply a total amount of 20N as the graft initial tension: 10N for the anterior two bundles and 10N for the posterior doubled graft in the triple-bundle ACL reconstruction,2 and 20N for the bone– patellar tendon–bone graft in the rectangular tunnel ACL reconstruction.3 After the intended amount of the tension is applied, the knee undergoes passive flexion-extension movement for several times, and the tensioning sutures are retightened by repetitive strong manual pull. After the tension stops to drop following load relaxation, the knee is maintained at 15 to 20 degrees under the tension for an additional 2 minutes. Finally, the graft is fixed with a DSP and cancellous screw (Fig. 44-6). Use of a metal rather than 326

FIG. 44-6 A radiograph showing fixation hardware. Note the Endobuttons are perpendicularly placed on the femoral cortex, whereas the doublespike plates and screws are installed in the tibia.

plastic hammer of higher mass makes it possible to gently strike the base spikes into the tibial cortex and to avoid breakage of the cortex by overstriking.

Double-Spike Plate: Cortical Fixation Device Enabling Graft Fixation Under Optional Tension At the time of double- or triple-bundle reconstruction, two tensioners should be used. It is our policy to accomplish tibial side fixation under the same tension between the anterior (anteromedial and intermediate) and posterolateral grafts at 15 to 20 degrees of flexion.

TENSION ACHIEVED IMMEDIATELY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION We have been routinely checking the restored anterior stability with KT-1000 or KT-2000 under anesthesia immediately after ACL reconstruction since 1999, when this device was introduced in our practice. None of the ACL-reconstructed knees has shown greater KT values than the opposite healthy knees. This has made our clinical results more consistent.

TROUBLESHOOTING If some soft tissue remained at the cortex for the DSP placement, the temporary fixation after hammering the base spikes could be somewhat unstable. In this situation, final fixation could be completed by inserting a screw while the DSP is stabilized with a microfracture awl through the bottom hole for suture tensioning.

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Even if the tibial cortex is somewhat broken by overhammering around the base spikes, the graft may not lose tension significantly as the top portion is stabilized on the cortex. In case the graft lost tension significantly, the DSP should be shifted medially or laterally and the procedure repeated. Excessive repetitive hammering by extra-strong manual force with a plastic hammer of lower mass may potentially break the graft sutures. In this worst-case scenario, the graft should be removed for replacing the graft sutures and the procedure repeated. Although use of thinner, higher-strength suture (e.g., Fiberwire by Arthrex, Naples, FL, and Xiros by Smith & Nephew, Andover, MA) could decrease the risk of this scenario, use of a metal hammer with higher mass is the key to completely avoiding this complication.

References 1. Shino K, Mae T, Maeda A, et al. Graft fixation with predetermined tension using a new device, the double spike plate. Arthroscopy 2002;18:908–911. 2. Shino K, Nakata K, Nakamura N, et al. Anatomic ACL reconstruction using two double-looped hamstring tendon grafts via twin femoral and triple tibial tunnels. Oper Tech Orthop 2005;15:130–134. 3. Shino K, Nakata K, Nakamura N, et al. Anatomically-oriented ACL reconstruction with a bone-patellar tendon graft via rectangular socket/tunnels: a snug-fit and impingement-free grafting technique. Arthroscopy 2005;21:1402.e1–1402.e5.

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45 CHAPTER

Don Johnson

SUB PART II INTERFERENCE SCREW–BASED

Anterior Cruciate Ligament Hamstring Graft Fixation with BioScrew XtraLok Tibial Fixation Device INTRODUCTION The fixation of soft tissue grafts and the fourbundle hamstring grafts have been the weak point of the anterior cruciate ligament (ACL) hamstring graft fixation. Kousa et al1 and Brand et al2 have published laboratory studies to provide some guidance in selecting the strongest fixation device. On the femoral side the crosspins and closed-loop Endobutton are more than double the strength needed for activities of daily living (1000N versus 450N). The tibial side remains the weak part of the construct. The IntraFix device (DePuy Mitek, Norwood, MA) has been reported to be around 1000N, and the staples on the cortex approximately 500N. Harvey et al3 demonstrated that screws with cortical fixation were almost twice the strength of screws that were placed in the cancellous bone portion of the tunnel. This presentation will describe the technique of using a cortical cancellous screw fixation for the fourbundle hamstring graft.

FIXATION OF THE GRAFT IN THE TIBIAL TUNNEL The four-bundle graft is pulled up through the tibial tunnel with the leader sutures attached to the Endobutton (Fig. 45-1). The graft is pulled 3 cm into the femoral tunnel. The Endobutton is flipped on the periosteal surface of the femur. The graft is pulled distally so that approximately 328

1 cm of graft is protruding out of the tibial tunnel. The sutures of the graft are attached to the tensioner. Approximately 50N of tension is applied to the semitendinosus graft and 30N of tension to the gracilis graft. The knee is cycled for 12 cycles, and the tension usually drops off in both grafts. This is reapplied and cycled again until the tension remains static. The flexible guidewire is inserted into the middle of the four bundles, and the XtraLok BioScrew (Conmed/Linvatec, Largo, FL) is inserted up the middle of the four bundles (Fig. 45-2). The stability of the knee is measured at the end of the fixation and compared with the preoperative manual maximum measurement of the opposite knee.

RESULTS We have performed a randomized clinical trial comparing the XtraLok BioScrew and IntraFix tibial fixation device. The results were given as a podium presentation at the Arthrosopy Association of North America (AANA) meeting in Vancouver in May 2005. There were no significant differences in the functional outcome or in the mechanical stability as measured by the KT-1000 arthrometer. The initial results did show a trend to lower KT values at the 1-year follow up. The BioScrew cortical fixation combined with the tensioner has given excellent and reproducible clinical results in hamstring soft tissue graft fixation.

Anterior Cruciate Ligament Hamstring Graft Fixation with BioScrew XtraLok Tibial Fixation Device

FIG. 45-1 The four-bundle hamstring graft.

FIG. 45-2 The tension is applied to each of the grafts, and the screw is inserted up the middle.

XTRALOK TIPS AND TROUBLESHOOTING The XtraLok tibial bioabsorbable screw comes in two lengths: 35 and 40 mm. It is available in 8-, 9-, 10-, and 11-mm sizes. The theory of the screw design is centered on the biomechanical principles that a centrally placed, longer, and larger screw with cortical fixation improves the pullout

45

strength of hamstring grafts on the tibial side. The screw is tapered from 8 mm at the insertion tip to 9 mm at the cortical end. It is recommended to use one size larger than the tibial tunnel. For example, if the tunnel is 7 or 7.5 mm, then the author uses an 8-  40-mm screw. The screw is designed to have the maximum purchase on the cortex. The screw should only be placed level with the cortex and not beyond. The nitinol guidewire is placed up the middle of the four bundles of hamstring graft. These are tensioned and separated by the mechanical SE tensioner (Conmed/Linvatec). The screw must be started with considerable axial load. Once the screw is inserted about halfway, the guidewire should be removed. This avoids pushing the guidewire into the joint or having the screw bind on the wire and break it. It is important to stop about one turn short of the screw being flush at the cortex. The depth of the screw is palpated with a finger, and after the graft is cut off, the screw can be inserted another turn if necessary. It is important not to insert the screw beyond the cortex as it loses 50% of its pullout if situated in only cancellous bone. The screw cannot be reversed, and when this happens, it should be advanced to the internal aperture to obtain proximal cortical fixation.

References 1. Kousa P, Jarvinen TL, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 2. Brand J Jr, Weiler A, Caborn DN, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 3. Harvey AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction. Knee 2003;10:97–102.

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46 CHAPTER

Charles H. Brown, Jr. Nader Darwich

330

Intratunnel Tibial Fixation of Soft-Tissue Anterior Cruciate Ligament Grafts: Graft Sleeve and Tapered Screw INTRODUCTION Tibial fixation of soft-tissue anterior cruciate ligament (ACL) grafts remains challenging.1–5 Tibial fixation is challenging because of the lower bone mineral density of the proximal tibia, the fact that tibial fixation devices must resist shear forces applied parallel to the axis of the tibial bone tunnel, and the longer time required for soft-tissue grafts to heal within the bone tunnels.2,6 Tibial fixation of soft-tissue grafts using screws and ligament washers that anchor to the tibial cortex can address many of these issues; however, these implants are often prominent and often cause local skin irritation and pain, requiring a second operation for removal.5 Intratunnel tibial fixation of softtissue grafts using interference screws avoids the problem of prominent hardware; however, laboratory biomechanical studies have shown that the tensile properties of soft-tissue grafts fixed with interference screws are highly dependent on bone mineral density, and this fixation technique often results in low initial fixation strength and slippage under cyclical loading.2,4,5 The Graft Sleeve and Tapered Screw (GTS) System (Smith & Nephew Endoscopy, Andover, MA) intratunnel tibial fixation technique was developed to increase the failure load and stiffness and to decrease slippage of four-strand soft-tissue grafts. The GTS System is an intratunnel tibial fixation technique that positions a polyL-lactic acid (PLLA) tapered, fine-pitch screw

concentrically within a four-strand soft-tissue graft. The tapered screw features shorter thread distance, which enhances compression of the soft-tissue graft in cancellous bone. The GTS System consists of the tapered screw and a three-lumen, woven, nonabsorbable polypropylene (PPE) mesh graft sleeve that organizes the four-graft strands in the tibial tunnel. The graft sleeve prevents graft twisting during screw insertion; maximizes bone–tendon contact, which enhances healing; and provides better compression of each ligament strand against the bone tunnel wall while protecting the graft strands from screw damage (Fig. 46-1).

BASIC SCIENCE Biomechanical Testing Biomechanical testing of the graft sleeve and tapered screw using human doubled gracilis and semitendinosus tendon (DGST) grafts has been performed in the proximal tibia of calf bone (2 years or younger) with bone mineral density similar to that of the proximal tibia in young humans.1,7 The tibia–DGST–graft sleeve complex was subjected to a 50N preload followed by cyclical loading between 50N and 250N at 1 Hz for 1000 cycles with the direction of tensile loading applied parallel to the axis of the tibial bone tunnel. Graft slippage was measured using a noncontact, three-camera, motion analysis system that allowed the position

Intratunnel Tibial Fixation of Soft-Tissue Anterior Cruciate Ligament Grafts: Graft Sleeve and Tapered Screw

FIG. 46-1 Graft Sleeve and Tapered Screw (GTS) System. The graft sleeve is a 15-mm-long, three-lumen, nonabsorbable, woven polypropylene mesh. The two bottom lumens (white threading tubes) are used to house the gracilis tendons, while the 1.5-mm guidewire and tapered screw is inserted through the single top lumen (blue threading tube). The outer suture acts as a cinch to hold the sleeve in place on the gracilis tendon during insertion into the tibial tunnel. The tapered screw is made of polyL-lactic acid (PLLA) and is available in sizes 7 to 9 mm  30 mm and 8 to 10 mm  30 mm.

of retroreflective bone and graft markers to be recorded in three dimensions during cyclic loading. Mean graft slippage, in which graft slippage was defined as the change in position of the tendon marker relative to the bone marker under the 50N preload and after cyclical loading, was 1.14
0.83 mm. The mean linear stiffness was 158
31 N/mm, and the mean failure load was 736
162 N, in which failure load was defined as the load when the load displacement curve substantially deviated from linear. The predominant mode of failure (60%) was pullout of the DGST tendons, graft sleeve, and tapered screw from the tibia. Comparison of the GTS System and the IntraFix Tibial Fastener (DePuy Mitek, Norwood, MA) using the just-mentioned testing protocol demonstrated no statistically significant differences in the cyclical and failure properties between the two devices.

46

an indicator of bone–tendon healing. CT slices in the axial plane demonstrated a progressive increase in healing at the bone–tendon interface over time. By 12 weeks a neocortex surrounded the tendon grafts. Based on the appearance of the signal intensity at the bone–tendon interface, the presence of the graft sleeve and tapered screw did not interfere with healing of the tendon to bone. No adverse reactions were noted related to the PLLA screw and PPE graft sleeve. Histological examination performed using a hard tissue technique in polymethylmethacrylate (PMMA) demonstrated that the PLLA screw compressed the tendons directly against the bone tunnel wall. These sections showed correct positioning of the PLLA screw in the PPE sleeve, as well as organization of the tendons in the PPE sleeve and bone tunnel to give a maximum bone–tendon interface (Fig. 46-2). Healing at the bone–tendon and tendon–screw interface was evaluated on paraffin sections stained with hematoxylin and eosin (H&E) and trichrome stains. Bone– tendon healing progressed over time and was observed in all specimens. The tendon grafts were compressed against the adjacent bone as a result of the screw being placed in the central lumen of the graft sleeve. The bone–tendon interface was composed of loose connective tissue, fibroblastic cells and local areas of bone–tendon integration. There was no evidence of macrophage or foreign body reaction at the bone–tendon interface (Fig. 46-3). Connective tissue was noted to infiltrate throughout the PPE sleeve, and no significant difference was seen between areas where the sleeve and screw were present and areas in the proximal part of the bone tunnel where only the tendon grafts were present. The interface between the tendon graft and screw was composed of a thin layer of loose connective tissue with

Biocompatibility and Histology of Fixation Site Healing Biocompatibility of the PLLA screw and PPE graft sleeve has been studied in a sheep model.8 Gross histological examination demonstrated that implantation of the PLLA screw and polypropylene graft sleeve had no adverse effect on the articular cartilage. Microscopic analysis of the synovial fluid using polarized light failed to detect the presence of any polymeric debris. Signal intensity at the bone–tendon interface evaluated by computed tomography (CT) was used as

FIG. 46-2 Polymethylmethacrylate (PMMA) cross-section perpendicular to the long axis of the screw. Histology at 3 weeks demonstrates central placement of the tapered screw and organization and compression of the four tendon graft strands in the tibial bone tunnel. (From Smith & Nephew Endoscopy, Andover, MA.)

331

Anterior Cruciate Ligament Reconstruction

FIG. 46-3 A, Cross-sectional histology at 6 weeks. The tendon graft is seen in the bone tunnel with healing at the tendon–bone interface. The interface tissue is composed of loose connective tissue, fibroblasts, and local areas of tendon–bone integration. B, 12-week histology demonstrating the tapered screw and the maturing tendon–bone interface. The interface between the screw and tendon graft consists of loose connective tissue with cellularity. The tendon graft is compressed against the adjacent bone as a result of the screw being placed into the central lumen of the graft sleeve. C, 52-week histology demonstrating tendon–bone healing with a well-defined interface. (From Smith & Nephew Endoscopy, Andover, MA.)

cellularity. There was no evidence of macrophage or foreign body reaction at the tendon–screw interface. In conclusion, histological analysis demonstrated the following: 1 The graft sleeve and tapered screw oriented the graft to provide the maximum contact area for tendon–bone healing. 2 Normal tendon–bone healing progressed throughout the bone tunnel with no differences between areas with and without the graft sleeve. 3 Tissue infiltrated freely throughout the sleeve and around the tapered screw. 4 No adverse reactions to the PLLA screw and polypropylene sleeve were observed. 332

SURGICAL TECHNIQUE Tibial fixation with the graft sleeve and tapered screw can be used with any four-strand soft-tissue ACL graft, provided the graft is long enough to reach the anterior tibial cortex after the graft has been fixed in the femur. The device is ideally suited for use with DGST tendon grafts, but it can also be used with doubled tibialis tendon allografts.

Advantages of the Graft Sleeve and Tapered Screw Compared with other intratunnel soft-tissue tibial fixation techniques, the advantages of the graft sleeve and tapered

Intratunnel Tibial Fixation of Soft-Tissue Anterior Cruciate Ligament Grafts: Graft Sleeve and Tapered Screw screw include consistent concentric insertion of the tapered screw, high screw insertion torque, uniform compression of the four-strand soft-tissue graft into the bone tunnel walls, and minimal rotation of the graft strands during screw insertion. Laboratory biomechanical testing has shown that these properties enhance initial graft fixation strength, stiffness, and resistance to slippage under cyclic loading.7,9 Finally, optimal surgical technique for implantation of the graft sleeve and tapered screw incorporates use of a mechanical tensioning device that equally tensions all four strands of the soft-tissue graft. Hamner et al10 have demonstrated in a laboratory biomechanical study that equal tensioning of all four strands of a four-strand hamstring tendon graft is necessary to maximize initial tensile strength and stiffness of the DGST graft.

Hamstring Tendon Graft Preparation Preparation of the hamstring tendon grafts and use of the GTS System are facilitated by the use of a graft preparation board (Graft Master II, Smith & Nephew Endoscopy). Residual muscle fibers on the musculotendinous end of both tendons are bluntly dissected off the tendons using a metal ruler, a large curette, or a Cushing-type periosteal elevator. The two tendon grafts are cut to the same length, and the ends of each tendon are tubularized with a running, baseball-style whipstitch using a #2 nonabsorbable suture. The sutures on each end of the tendon grafts are tensioned with a “cinching” motion to remove excess slack from the whipstitches. The two tendon grafts are looped around a #5 nonabsorbable suture, creating a DGST graft. The diameter of the DGST graft is measured to the nearest 0.5 mm using a 0.5-mm incremental sizing block. The diameter of the combined grafts is usually 7 to 8.5 mm in males and 6.5 to 8 mm in females. The ends of the DGST graft are equalized in length and the axilla of the DGST graft looped around an Endobutton tensioning post. The DGST graft is covered with a moist laparotomy pad and pretensioned to 5 pounds on the graft preparation board for the remainder of the procedure.

Tibial Tunnel A tibial tunnel length of 40 to 50 mm is optimal because this length range will allow the 30-mm-long tapered screw to be inserted flush with the tibial cortex, with there being no possibility that the screw will protrude into the intraarticular aspect of the knee joint. Setting the adjustable tibial aimer between 50 and 55 degrees will usually allow these tunnel lengths to be achieved. If the transtibial tunnel technique is used to drill the femoral tunnel, the starting position of the tibial guide pin must be located adjacent to the anterior fibers of the medial collateral ligament (MCL). This is necessary to

46

achieve the correct tunnel angulation so that the femoral tunnel can be oriented at the 10-o’clock position. Laboratory biomechanical studies have demonstrated that single-tunnel ACL grafts placed at the 10-o’clock position provide better rotational control compared with ACL grafts placed at the 11-o’clock position.11 The starting location of the tibial guide pin is not critical if the femoral tunnel is drilled using the anteromedial portal technique. A tight fit of the soft-tissue ACL graft in the bone tunnels is desirable to optimize tendon–bone healing.12 To ensure a tight fit, half-millimeter size drill bits are used to drill the bone tunnels. To prevent anterior drift of the tibial tunnel, a cannulated, rear entry–style drill is used to drill the tibial tunnel. Because attaching the graft sleeve to the DGST graft increases its diameter, it is necessary to overdrill the first 10 to 15 mm of the tibial tunnel by 1 mm greater than the measured size of the ACL graft. The remainder of the tibial tunnel is drilled using a drill size equal to the measured diameter of the DGST graft. Half-round or angled ACL chamfering rasps are used to smooth the intraarticular edge of the tibial tunnel to minimize graft abrasion. To ensure smooth passage of the graft sleeve into the tibial tunnel, it is important to clear soft tissue from around the edges of the tibial tunnel using an electrocautery pencil and a Cobb periosteal elevator.

Femoral Tunnel and Fixation The graft sleeve and tapered screw can be used with any femoral fixation technique. However, because of its high strength, minimal slippage, and ease of use, we prefer femoral fixation with the Endobutton-CL.13 The femoral tunnel can be created using the transtibial tunnel or anteromedial portal techniques. The femoral guide pin is positioned at the 10-o’clock position along the sidewall of the lateral femoral condyle, and the Endobutton femoral tunnel and closedend femoral socket are drilled in the usual fashion.14 An Endobutton depth gauge with adjustable knob (Smith & Nephew Endoscopy) is used to measure the femoral tunnel length and the total tunnel length (distance from the lateral femoral cortex to the superior margin of the anterior tibial cortex) (Fig. 46-4). These measurements are used to calculate the Endobutton-CL length and the location for attaching the graft sleeve on the gracilis tendon graft. If interference screw or cross-pin fixation techniques are used, the total tunnel length is measured from the end of the closed-end femoral socket to the anterior tibial cortex.

Application of the Graft Sleeve The appropriate-length Endobutton-CL is inserted into the Endobutton holder with extender (Smith & Nephew

333

To ta lt

un ne l

le ng th

Fe m

or al tu nn el le ng th

Anterior Cruciate Ligament Reconstruction passage, we have found it helpful to position the sleeve 10 mm closer to the Endobutton end of the graft. After verifying that the blue threading tube lies in the third lumen of the sleeve, the graft sleeve is attached to the gracilis tendon by securely tying the preinserted cinching suture. To provide additional security and to prevent the leading edge of the sleeve from puckering and impinging at the entrance of the tibial tunnel, we have found it helpful to loop and tie an additional #0 absorbable suture around the leading edge of the graft sleeve. The semitendinosus strands are equalized in length and the whipstitches are attached to the superior knobs of the tensioner. The semitendinosus strands should straddle the right/left sides of the top lumen on the graft sleeve and rest on the top surface of the lower two lumens containing the gracilis tendon (Fig. 46-5).

Graft Passage FIG. 46-4 Measurement of femoral tunnel length and total tunnel length using the Endobutton depth gauge with adjustable knob. (From Smith & Nephew Endoscopy, Andover, MA.)

Endoscopy) and the DGST graft passed through the continuous loop. The DGST graft is marked at the previously measured femoral tunnel length. The ends of the doubled semitendinosus tendon graft are equalized in length, the sutures are clamped together with a small surgical clamp, and the semitendinosus tendon graft is flipped off the side of the Endobutton holder with extender. The Graft Tensioning Device (Smith & Nephew Endoscopy) is inserted into the tensioner device holder (Smith & Nephew Endoscopy), and the back of the tensioner device holder is positioned on the GraftMaster II board at the 18-cm mark. The Endobutton depth gauge with adjustable knob is used to mark the doubled gracilis tendon at the previously measured total tunnel length. This mark is used to position the graft sleeve on the gracilis tendon. If the femoral tunnel was drilled through the anteromedial portal, the end of the Endobutton depth gauge is positioned at the previously marked femoral tunnel length and the gracilis tendon is marked at a distance that equals the intraarticular length of the ACL plus the tibial tunnel length. The sutures on the end of the gracilis tendon are threaded through the white, plastic threading tubes of the graft sleeve and the gracilis sutures attached to the lower knobs of the tensioner. It is important that the graft sleeve be attached to the gracilis tendon such that the cinching suture is positioned toward the Endobutton-CL. The white, plastic threading tubes are removed from the graft sleeve, and the sleeve is positioned on the gracilis at the previously marked total tunnel length. Because the graft sleeve has a tendency to slide distally on the gracilis tendon during graft 334

A full-length #5 Fiberwire (passing suture) and #2 highstrength nonabsorbable suture (flipping suture) are passed through the end holes of the Endobutton. We recommend against the use of conventional #5 polyester passing suture because it may break during graft passage as a result of the greater force required to advance the graft sleeve into the tibial tunnel. The Endobutton sutures are passed across the joint and out the lateral thigh using a 2.7-mm, drilltipped passing pin. Maintaining slight tension on the tibial end of the DGST graft using the tensioner handle, the Endobutton and the attached hamstring tendon graft are passed across the knee joint and into the femoral socket using the #5 Fiberwire passing suture. The DGST graft must be advanced until a mark previously placed at the femoral tunnel length is seen to pass up into the femoral socket approximately 6 mm. This extra distance allows the Endobutton to pass outside the lateral femoral cortex and flip. Tension is

FIG. 46-5 Each end of the gracilis tendon is passed through one of the two lower lumens of the graft sleeve. The 1.5-mm guidewire for the tapered screw is inserted into the third lumen of the sleeve, and the sleeve is secured to the gracilis tendon by tying the preinserted cinching suture.

Intratunnel Tibial Fixation of Soft-Tissue Anterior Cruciate Ligament Grafts: Graft Sleeve and Tapered Screw applied to the tibial end of the graft, and the surgical mark previously placed at femoral tunnel length will be seen to slide back down the femoral tunnel. If the measurements are correct, this mark should lie at the entrance of the femoral tunnel and the graft sleeve should be slightly recessed or lie flush with the entrance of the tibial tunnel.

Tibial Fixation The knee is cycled from 0 to 90 degrees for a minimum of 30 cycles with a preload of 80N to 100N applied to the DGST using the tensioning device. Cycling of the knee under a preload allows the Endobutton-CL to settle on the femoral cortex and removes creep from the continuous loop and DGST graft. At the present time, the optimal graft tension and knee flexion angle during tibial fixation are unknown. Depending on the graft excursion pattern detected while cycling the knee, we fix the graft with the knee between 0 and 20 degrees of flexion. The usual graft excursion pattern detected with our bone tunnel placements results in the DGST graft pulling into the tibial tunnel a few millimeters during the last 20 degrees of terminal extension. When minimal graft excursion is detected, we tend to fix the graft with the knee at 20 degrees of flexion and near full extension with greater excursions. Because of the high fixation strength and stiffness and the resistance to slippage of the graft sleeve and tapered screw, we caution against applying excessive tension (greater than 80N) to the graft or fixing the knee at a flexion angle greater than 30 degrees. High graft tension force in combination with the knee flexed more than 30 degrees can overconstrain or “capture” the knee. With the knee held at the desired flexion angle and 80N applied to the DGST graft, a 1.5-mm guidewire is inserted through the blue threading tube into the knee joint. The blue threading tube is removed, leaving the guidewire in place in the third lumen of the graft sleeve. If the diameter of the DGST graft is 6 to 8.5 mm, we recommend use of the 7- to 9-mm  30-mm tapered screw. For larger graft sizes, the 8- to 10-mm  30-mm tapered screw is used. The appropriate-sized tapered screw is inserted onto the BioRCI screwdriver (Smith & Nephew Endoscopy) and the screw advanced over the guidewire into the third lumen of the graft sleeve. While maintaining an 80N load on the DGST graft, the tapered screw is screwed into the graft sleeve and up into the tibial tunnel until the end of the screw is flush with the anterior tibial cortex (Fig. 46-6). Insertion of the tapered screw is usually accompanied by a “squeaking” feel and sound. Because the best bone quality is at or next to the anterior tibial cortex, inserting the tapered screw too deeply may decrease fixation strength.9

46

The fixation strength of any intratunnel fixation device is dependent on the local bone mineral density.1,2,5 If the surgeon believes that there was inadequate insertion torque during the insertion of the tapered screw or if the patient has soft bone, then we recommend that supplemental tibial fixation be used.3 Depending on the graft length, the protruding DGST tendons can be stapled below the tibial tunnel using a small barbed staple (Smith & Nephew Orthopaedics, Memphis, TN), or the sutures can be tied around a extra-small, nonbarbed staple or tibial fixation post (Smith & Nephew Endoscopy) (Fig. 46-7). The stability and range of motion of the knee are checked. It is important to verify that the patient has full range of motion before leaving the operating room. The arthroscope is inserted into the knee, and graft tension and impingement are assessed. Our usual graft placement and tensioning technique results in the four strands of the DGST being maximally tight between 0 and 20 degrees, with the graft tension decreasing slightly as the knee is flexed to 90 degrees (Fig. 46-8). After confirming that the patient has a full range of motion and normal anterior laxity, the passing and flipping sutures are pulled out of the lateral thigh.

POSTOPERATIVE MANAGEMENT Follow-Up The patient is seen at 7 to 10 days for suture removal and postoperative radiographs (Fig. 46-9).

Rehabilitation Our postoperative rehabilitation protocol is described in Table 46-1. The weight-bearing schedule is modified if a meniscus repair, microfracture, or other associated ligamentous surgery has been performed.

USE OF THE GRAFT SLEEVE WITH TIBIALIS TENDON ALLOGRAFTS Due to the potential issues of graft–tunnel mismatch and the lack of availability of bone–patellar tendon–bone (BPTB) allografts, double-stranded anterior and posterior tibial tendon (tibialis tendon) allografts have become an increasingly popular graft choice for ACL reconstruction. At the present time, bioabsorbable interference screws are most commonly used for tibial fixation of tibialis tendon allografts. For surgeons desiring improved initial fixation properties, it is

335

Anterior Cruciate Ligament Reconstruction

A

B FIG. 46-6 A, The tapered screw is advanced over the 1.5-mm guidewire into the third lumen of the graft sleeve. B, Tibial fixation is completed by inserting the tapered screw until it is flush with the anterior tibial cortex. (From Smith & Nephew Endoscopy, Andover, MA.)

336

Intratunnel Tibial Fixation of Soft-Tissue Anterior Cruciate Ligament Grafts: Graft Sleeve and Tapered Screw

A

46

B

FIG. 46-7 Supplemental tibial fixation. A, The tendons are fixed to the tibia with a barbed ligament staple. B, The tendon whipstitches are tied around a screw and washer. (From Smith & Nephew Endoscopy, Andover, MA.)

FIG. 46-8 Arthroscopic appearance of the doubled gracilis and semitendinosus tendon (DGST) graft demonstrating equal tensioning of the graft strands. Note that the femoral attachment site of the graft is located along the sidewall of the lateral femoral condyle and the graft is oriented at a 10-o’clock position in the notch.

possible to modify the ends of the tibialis tendon allograft to allow use of the graft sleeve and tapered screw. The tibialis tendon allograft is thawed and looped around a #5 suture, creating a double-stranded graft. The diameter of the doubled tibialis allograft is measured to the nearest half-millimeter as previously described. After drilling the tibial and femoral bone tunnels, the Endobutton depth gauge with adjustable

knob is used to measure the femoral tunnel length, the total tunnel length, and the length of the tibial tunnel. The appropriate-length Endobutton-CL is selected, and the tibialis allograft is passed through the CL loop, creating a doubled tibialis tendon allograft. The total tunnel length is marked on the tibialis allograft as previously described. This mark serves to locate the position for attaching the graft sleeve. Using the total tunnel length mark as the starting point, a second mark that equals the length of the tibial tunnel is made toward the Endobutton end of the graft. The free ends of the tibialis tendon allograft are split in half with a 15 knife blade up to the tibial tunnel length mark, creating four tendon graft strands. The four graft strands are whipstitched using a #2 nonabsorbable suture. The graft sleeve is attached in the usual fashion to two strands of the doubled tibialis tendon allograft (Fig. 46-10). The tibialis tendon allograft is passed and fixed in the femur as previously described. The knee is cycled 30 times with a preload of 100N applied to the graft strands. While maintaining an 80N load on the tibialis tendon allograft, the tapered screw is screwed into the graft sleeve and up into the tibial tunnel until the end of the screw is flush with the anterior tibial cortex.

PEARLS AND PITFALLS OF THE TECHNIQUE The most common technical problems encountered during use of the graft sleeve and tapered screw are (1) the difficulty in getting the sleeve to pass into the tibial tunnel and (2) the 337

Anterior Cruciate Ligament Reconstruction

FIG. 46-9 Postoperative radiographs. A, The tibial tunnel forms a 65-degree angle with the joint line. Proper tibial tunnel placement results in placement of the Endobutton at the flair of the distal femur. B, Lateral radiograph in maximum hyperextension. The tibial tunnel is parallel and posterior to Blumensaat’s line.

sliding of the sleeve on the soft tissue graft, resulting in part or all of the sleeve coming to lie outside of the tibial tunnel. These problems can be prevented by the following:

 Tying a “purse-string” #0 nonabsorbable suture around

 Overdrilling the first 10 mm of the tibial tunnel 1 mm

 Avoiding the use of a strong nonabsorbable “purse-string”

greater than the measured size of the soft tissue graft

 Removing soft tissue from the entrance of the tibial tunnel

 Making sure that the graft sleeve is attached to the soft tissue graft with the cinching suture oriented toward the Endobutton end of the graft

 Verifying that the blue threading tube for the 1.5-mm guidewire is inserted into the third lumen of the graft sleeve before securing the sleeve to the soft tissue graft

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the leading edge of the graft sleeve to help further secure the sleeve to the soft tissue graft suture because it may not break during insertion of the tapered screw, preventing advancement of the tapered screw into the third lumen of the graft sleeve

 Using a #5 Fiberwire suture as the Endobutton passing suture

RESULTS We have performed more than 30 hamstring ACL reconstructions using graft sleeve and tapered screw tibial fixation

TABLE 46-1 Hamstring Anterior Cruciate Ligament Postoperative Rehabilitation Protocol Goals

Exercises

46

Phase I: Days 0–7 Control pain, inflammation, joint effusion, swelling Knee CryoCuff, thigh-length TED stocking, elevation Full passive extension equal to the opposite knee Heel props, pull knee into hyperextension using elastic band Achieve 90 degrees of flexion

Wall slides, gravity assisted flexion sitting on the edge of a table

Prevent quadriceps shutdown

EMS, quad isometrics, SLR, active-assisted extension 90–0 degrees

Prevent heel cord contracture

Ankle pumps, calf stretches with elastic bands

Gait training

Weight bearing as tolerated with knee immobilizer and crutches Meniscus repair, revisions: " 25% BW/week, wean off crutches end of week 4

Phase II: Weeks 1–2 Control inflammation, pain, joint effusion, swelling Continue Phase I exercises Maintain full symmetrical extension

Continue Phase I exercises

Achieve 100–125 degrees of flexion

Assisted flexion using opposite leg, wall slides, heel drags, rolling stool

Develop muscular control to safely wean off knee Continue Phase I exercises, mini-squats, toe raises, active extension 90–30 degrees immobilizer and crutches Protect hamstring donor site

Prevent sudden, forceful hamstring stretching with the knee and hip in extension, such as attempting to lean forward and put on socks and shoes or leaning forward to pick up an object off the floor

Phase III: Weeks 2–4 Maintain symmetrical extension

Heel props, prone heel hangs, lock knee out, “stand at attention”

Wean off knee immobilizer

Patients who fail to obtain symmetrical extension should be considered for extension splinting or a “drop-out” cast; discard immobilizer when able perform SLR without a quad lag

Wean off crutches

One crutch when able to bear 75% BW; discard crutches when full weight bearing and able to walk with normal heel–toe gait

Achieve 125–135 degrees flexion

Heel slides, sitting back on heels

Hamstring strengthening

Hamstring isometrics 0–90 degrees, pulling, rolling, rolling stool backwards

Quadriceps strengthening

Continue Phase II exercises, mini-squats with elastic band for resistance

Hip strengthening

Side-lying hip abduction, adjustable-angle hip machine

Proprioceptive training

Balance board double-leg stance

Aerobic conditioning

Elliptical machine

Phase IV: Weeks 4–6 Obtain full flexion

Heel slides, sitting back on heels

Continue quadriceps, hamstring, and hip

Mini-squats, leg press 50–0 degrees, front step-ups (control hip valgus), StairMaster backward, PNF,

strengthening

toe raises, seated leg curl machine 0–90 degrees

Proprioceptive training

Balance board double- and single-leg stance, add ball throws and catches

Aerobic conditioning

Stationary bike (adjust to protect PFJ), elliptical machine, pool exercises

Phase V: Weeks 6–12 Increase lower extremity strength and endurance Increase intensity Phase IV exercises, high-speed (300–360 degrees/sec) isokinetics extension (90–30 degrees)/flexion (0–90 degrees), elliptical machine, StairMaster backward and forward, treadmill walking, pool exercises Advance proprioceptive and perturbation training Increase intensity of Phase IV exercises Phase VI: Weeks 12–16 Increase quad and hamstring strength

Increase intensity of Phase IV exercises, mid-range (180–240 degrees/sec) isokinetics extension (90–30 degrees)/flexion (0–90 degrees)

Increase hamstring strength at high-flexion angles Prone leg curls with elastic tubing and leg curl machine (90–120 degrees) Jogging and running

Treadmill jogging and running, outdoor running on low-impact surface

Crossover drills

Lateral step-over, carioca drills

Phase VII: Weeks 16–24 Hard cutting and sports-specific drills

Figure-eight, circle run, plyometrics, hopping, jumping, sprinting

Return to noncontact sports at 4–5 months

Golf, tennis, biking, hiking

Return to full sports at 6 months (revisions, 9 months) BW, Body weight; EMS, electrical muscle stimulation; PFJ, patellofemoral joint; PNF, proprioceptive neuromuscular facilitation; SLR, straight leg raises.

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Anterior Cruciate Ligament Reconstruction tissue–bone healing. Because of the woven, porous nature of the graft sleeve and the demonstrated ability of the interface tissue to infiltrate throughout the sleeve, the graft sleeve should serve as an ideal carrier when the appropriate biological enhancement factors are identified.

References

FIG. 46-10 A, Preparation of tibialis tendon allograft for tibial fixation with graft sleeve and tapered screw. The ends of the tibialis tendon allograft are split and whipstitched with a #2 nonabsorbable suture. B, Two of the split ends are threaded through the graft sleeve, and the sleeve is secured to the tibialis tendon allograft by tying the cinching suture.

since the device became clinically available. There have been no infections, recurrent effusions, or other complications related to the device. The early objective stability and clinical results are similar to those we reported using the IntraFix tibial fastener.14 However, due to the higher insertion torque and the tighter fit in the tibial tunnel, we have used supplemental tibial fixation less frequently.

FUTURE OF THE TECHNIQUE An osteoconductive tapered screw (Calaxo Screw, Smith & Nephew Endoscopy) that will integrate in the tibial tunnel and be replaced by bone within 1 year is currently under development. This would preserve bone stock and eliminate the need for screw removal in revision cases. One of the major differences between ACL reconstructions performed using BPTB and hamstring tendon autografts is the faster fixation site healing of patellar tendon grafts. Ongoing basic science research is directed at promoting and accelerating healing of soft tissue grafts to bone. Bone morphogenic proteins and biological growth factors are currently being investigated as possible methods to promote and accelerate soft

340

1. Brand JC, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 2. Brand JC, Weiler A, Caborn DNM, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 3. Hill PF, Russell VJ, Salmon LJ, et al. The influence of supplementary tibial fixation on anterior laxity measurements after anterior cruciate ligament reconstruction with hamstring tendons in female patients. Am J Sports Med 2005;33:94–101. 4. Kousa P, Jarvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182––174. 5. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 6. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon healing in a bone tunnel: a biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 7. Hecker AT, Blough R. GTS Sleeve vs. IntraFix Fastener: a biomechanical comparison of initial fixation properties. Report on file at Smith & Nephew Endoscopy, Andover, MA. 8. Cotton NJ, Blough RA. Histological evaluation of the GTS Sleeve/GTS Tapered Screw intratunnel tibial fixation system in an ovine model. Report on file at Smith & Nephew Endoscopy, Andover, MA. 9. Harvery AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction. Knee 2002;10:97–102. 10. Hamner DL, Brown CH, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg 1999;81A:549–557. 11. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel positions. Arthroscopy 2003;19:297–304. 12. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex: a biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 13. Brown CH, Wilson DR, Hecker AT, et al. Graft-bone motion and tensile properties of hamstring and patellar tendon anterior cruciate ligament femoral graft fixation under cyclic loading. Arthroscopy 2004;20:922–935. 14. Brown CH, Sklar JH, Darwich N. Endoscopic anterior cruciate ligament reconstruction using autogenous doubled gracilis and semitendinosus tendons. Tech Knee Surg 2004;3:215–237.

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener INTRODUCTION The optimal initial graft fixation technique for hamstring tendon anterior cruciate ligament (ACL) grafts remains controversial.1–6 Biomechanical studies have demonstrated that cross-pin and Endobutton-CL femoral fixation techniques provide excellent initial fixation properties.7,8 However, tibial fixation of hamstring tendon ACL grafts has been more problematic. This is primarily due to the lower bone mineral density of the proximal tibia and the fact that tibial fixation devices must resist tension applied parallel to the axis of the tibial bone tunnel.2,9–11 Extratunnel tibial fixation techniques that anchor to the tibial cortex can provide secure initial fixation; however, the implants are often prominent and cause local skin irritation and pain, requiring a second operation for removal.12 Intratunnel tibial fixation using interference screws eliminates the problem of prominent hardware, but the single interference screw technique has been shown to have somewhat low initial fixation strength and increased slippage under cyclical loading.2,4,9,13 The IntraFix tibial fastener was designed with two goals in mind, one mechanical and one biological. The first goal was to achieve more rigid intratunnel fixation of soft tissue grafts and eliminate or decrease the need for supplemental tibial fixation. The second goal was to maximize bony integration of the soft tissue graft strands into the bone tunnel wall. To achieve these goals,

the device was designed with an expandable, four-channel, ridged, 30-mm polyethylene sheath and a tapered Delrin expansion screw. The four channels individually capture and grip each of the four strands of the hamstring tendon graft into separate compartments and directly compress each of the graft strands against cancellous bone. We performed cyclical and single load to failure (LTF) tests comparing the plastic IntraFix and bioabsorbable interference screws in paired young to middle-aged human cadaver tibiae with human doubled gracilis and semitendinosus grafts (DGSTs) (Table 47-1). The plastic IntraFix demonstrated a mean ultimate failure load of 800N and stiffness of 200 N/mm, which was significantly higher than interference screw fixation. In an independent biomechanical study comparing commonly used hamstring tendon graft tibial fixation devices, Kousa et al14 demonstrated that the IntraFix had the highest LTF (1309N) and stiffness (267 N/mm) and the least amount of slippage (1.5 mm) after cyclical loading. Following the successful clinical introduction of the nonabsorbable IntraFix tibial fastener, a Bio-IntraFix composed of poly-Llactic acid/tricalcium phosphate (PLLA/TCP) was developed to satisfy the desire of some surgeons for a bioabsorbable device. Testing of the Bio-IntraFix using DGST and paired human cadaveric tibiae (mean age 63  10 years) was performed with the line of force applied parallel to the axis of the tibial tunnel. Elongation was measured using a video camera system to determine displacement of contrast

47 CHAPTER

Joseph H. Sklar Charles H. Brown, Jr.

341

Anterior Cruciate Ligament Reconstruction TABLE 47-1 Sizing Scheme for Bio-IntraFix Graft Diameter

Drill Tunnel

Screw Size

7 mm

8.5 mm

6–8 mm

8 mm

9.0 mm

6–8 mm

9 mm

10.0 mm

7–9 mm

10 mm

11.0 mm

8–10 mm

markers attached to the graft and bone. The graft–BioIntraFix–bone complex was cyclically loaded between 50N and 200N at a rate of 0.5 Hz for 1000 cycles (33 min, 20 sec). One thousand cycles approximates 1 week of postoperative intermittent passive motion. The mean ultimate failure load and linear stiffness for the Bio-IntraFix were 643  152N and 325  111 N/mm, respectively. Elongation after 1000 cycles was 2.28  1.19 mm. The failure load of the Bio-IntraFix was found to be superior to that of the Delta screw (Arthrex, Naples, FL), and the stiffness was two times that of the Delta Screw. During cyclical loading, three of six Delta screws failed compared with only one of six DGST grafts fixed with the Bio-IntraFix. The second goal of this design was to maximize the amount of contact between graft tendons and bone. Fixation outside tunnels and from suspension devices results in a loose fibrous attachment between the tunnel wall and the graft, with little if any bony ingrowth into the graft (Fig. 47-1). In contrast, direct compression of tendon to bone by interference screws within the tunnel leads to bony ingrowth including Sharpey fiber formation.15 However, a single interference screw inserted next to a bundled fourstranded graft definitely leaves a considerable portion of the tunnel filled by the screw and some of the tendons without bony contact. In contrast, the IntraFix has the potential for more extensive bone–graft integration because each strand is pressed against bone and the entire tunnel wall is in contact with graft. A limited histological study performed on the IntraFix in sheep demonstrated early bony integration (Fig. 47-2). Thus extrapolation of the interference screw data to this device seems justified. Further evidence of extensive bony integration when using the IntraFix and Bio-IntraFix comes from direct examination of the tibial tunnel many months after reconstruction. Fig. 47-3 shows an example of the appearance of the tibial tunnel 1 year after ACL reconstruction; it was obtained during a revision case after the sheath had been removed and the arthroscope inserted into the tibial tunnel. It shows a firm surface, apparent integration of the sutured tendons into the bone tunnel wall, capillary ingrowth, and no loose fibrous tissue. 342

FIG. 47-1 Transaxial magnetic resonance image of the tibia in an anterior cruciate ligament (ACL) reconstructed patient showing a cannulated screw anteriorly and a graft bundle posteriorly. Note the very limited contact of the graft bundles with the surface of the bone tunnel.

Bone ingrowth Graft tissue

FIG. 47-2 Histology 12 weeks after reconstruction of the anterior cruciate ligament (ACL) in a sheep using autogenous extensor tendons and tibial fixation with IntraFix, seen at the bottom right of slide. Note Sharpey fiber formation (linear strands) and new bone ingrowth (dark blue) into tendon (light blue).

SURGICAL TECHNIQUE Graft Preparation Preparation of the tendons is facilitated by the use of a graft preparation board. The two tendons are cut to a total length of 20 to 21 cm, and the opposite ends of the tendons are whipstitched for 4 to 5 cm using a #2 nonabsorbable suture. This length of tendon graft allows for 25 mm of the DGST tendon graft to be inserted into the femoral tunnel and typically results in a significant length of suture-reinforced tendon within the tibial tunnel and a short (1-cm) length of the tendons extending outside the tibial tunnel. If more of the DGST tendon graft is inserted into the femoral tunnel, or if the tibial tunnel is longer than 40 to 45 mm, then the

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener total length of the two tendons should be increased accordingly. This is important because suture-reinforced tendon constructs have been shown to increase pullout strength by 30% to 40% in our laboratory biomechanical tests.

Use with Allografts If a soft tissue allograft such as a tibialis tendon is used, we prefer to divide each end of the allograft in two for a distance of 5 cm and then to whipstitch each strand so that a four-stranded construct comparable to a DGST is created. The IntraFix four-chambered sheath accommodates and provides more uniform compression with a four-strand graft preparation compared with a two-stranded graft. The graft construct is then placed on a tensioning board, cinching the whipstitched sutures and removing creep from the graft construct. Removing creep from the graft–suture construct is particularly important if supplemental fixation is required.

Tibial Tunnel Our preferred method for performing endoscopic ACL reconstruction is the transtibial tunnel technique. The transtibial technique allows a longer femoral tunnel to be drilled compared with drilling the femoral tunnel through the anteromedial portal and also allows cross-pins to be used for the femoral fixation. Another advantage of the transtibial technique is that the femoral tunnel does not have to be drilled with the knee in hyperflexion, which constricts fluid inflow and limits visualization in the notch. The disadvantage of the transtibial tunnel technique is that it provides more limited access to the sidewall of the lateral femoral condyle compared

47

with drilling the femoral tunnel through the anteromedial portal. The tibial tunnel must be carefully oriented in both the sagittal and coronal planes for several reasons. Due to the large cross-sectional area of four-strand hamstring tendon grafts, sagittal placement of the tibial tunnel is especially critical.16 The tibial tunnel position in the sagittal plane determines whether the ACL graft impinges against the roof of the intercondylar notch in full knee extension.2,16–19 Roof impingement is associated with effusions, loss of extension, anterior knee pain, quadriceps weakness, and increased anterior laxity. Coronal plane orientation is the primary determinant of placement of the femoral tunnel along the side wall of the intercondylar notch and, to some degree, of the length of the femoral tunnel. A more medial starting position on the tibia allows the femoral tunnel to be drilled closer to the 10- or 2-o’clock position along the sidewall. A femoral tunnel at the 10-o’clock (right knee) or 2-o’clock position (left knee) is important because a single-bundle ACL graft positioned at these locations in the intercondylar notch is more effective at resisting combined rotatory loads than one placed at the 11-o’clock position. Biomechanical studies have demonstrated little difference in coupled anterior tibial translation between this graft and a double-bundle hamstring ACL reconstruction at low degrees of flexion.20 In our surgical technique, a tibial tunnel length of 35 to 45 mm is optimal because this will accommodate the entire 30-mm IntraFix or Bio-IntraFix with no chance of the device protruding into the joint. In general, setting the variable angle tibial aimer between 45 and 55 degrees will allow these tibial tunnel lengths to be achieved. The guidelines of Jackson and Gasser,21 Howell,15 and Simmons et al22 are used for intraarticular placement of the tibial guide pin. If necessary, the tibial guide pin position can be checked by intraoperative radiographs or fluoroscopy with the knee in maximum extension.

Tunnel Sizing

FIG. 47-3 Appearance of the tibial tunnel using an arthroscope during revision surgery following removal of the IntraFix device. Note the apparent integration of tendons/sutures 360 degrees around the tunnel and imprint of the sheath’s ridges.

When using the plastic IntraFix, the diameter of the tibial tunnel should equal the diameter of the suture-reinforced end of the graft. When using the Bio-IntraFix, the tibial tunnel should be drilled 0.5 to 1.0 mm larger than the diameter of the suture-reinforced end of the graft because the Bio-IntraFix sheath does not compress or flow during screw insertion. Biomechanical testing of this oversized scheme showed no loss of fixation strength for the Bio-IntraFix compared with tunnels sized to the same diameter as the graft. Half-millimeter–sized drill bits can be used to make this sizing more precise. The tibial tunnel should be drilled with a fluted drill to prevent anterior drift of the tunnel as the proximal cortex is breeched. After drilling the tibial tunnel, it is important to clear soft tissue from around the edges of the tibial tunnel using 343

Anterior Cruciate Ligament Reconstruction an electrocautery pencil and a Cobb periosteal elevator for several reasons. First, a clear view is necessary to ensure that the tab of the IntraFix sheath is flush with the tibial cortex and that the sheath is fully inserted. Second, a clear view helps ensure that the screw is neither over- nor underinserted into the tunnel. Finally, clearing of soft tissue also improves the ability to see and trim excess tendon and sheath at the end of the case so that there is no prominence that might later irritate the patient.

Femoral Tunnel and Graft Fixation Because the IntraFix tibial fastener can be used with any femoral fixation technique, the choice of the femoral fixation is based on the surgeon’s preference. However, we prefer cross-pins or the Endobutton-CL because these fixation techniques have been shown to be strong and stiff and to have the least amount of elongation under cyclical loading.7,8 More importantly, these two femoral fixation techniques permit equal tensioning of all four graft strands. This is an important goal because, as shown by Hamner et al,23 it is necessary to equally tension all four strands of a DGST graft to maximize initial graft strength and stiffness. An equally tensioned DGST graft was stronger and stiffer than a 10mm, central-third patellar tendon autograft. However, when no attempt was made to equally tension all four graft strands, the ultimate failure load and stiffness of the DGST graft were not statistically different from that of a doubled semitendinosus tendon graft alone. Thus failure to equally tension all four graft strands of a DGST graft negated any contribution from the doubled gracilis tendon graft.

Graft Passage, Graft Tensioning, and Tibial Fixation For the IntraFix device to function properly, the strands of the graft need to be parallel and untangled within the tibial tunnel. This can be accomplished easily if the surgeon arranges the strands in this way as the graft is drawn into the knee by the assistant. After the femoral side of the DGST or tibialis tendon allograft has been securely fixed in the lateral femoral condyle, the whipstitches from the gracilis tendon or corresponding opposite ends of the tibialis tendon allograft are tied together to create a loop approximately 4.5 to 5 inches from the end of the tibial tunnel. This step is repeated for the semitendinosus tendon and the corresponding opposite ends of the tibialis tendon allograft (Fig. 47-4, A and B). The two suture loops are placed around the tie tensioner (DePuy Mitek, Norwood, MA) but can be held by hand. The tie tensioner frees one hand for the surgeon. Because it contains a calibrated spring, it allows for quantification of the tension applied to the graft at the time of fixation. Prior

344

to inserting the IntraFix, the knee is cycled from 0 to 90 degrees approximately 25 to 30 times with a tension of 60N to 80N maintained on the graft limbs. The tie tensioner will equally tension and separate each strand of the DGST graft. Cycling allows stress relaxation of the femoral fixation device, allows the tendons to compress around the cross-pin or Endobutton-CL, and removes creep from the DGST or tibialis tendon allograft and the tendon whipstitches. At present the optimal graft tension and knee flexion angle at the time of tibial fixation are unknown. The usual excursion pattern detected with our bone tunnel placements results in the DGST graft pulling into the tibial tunnel a few millimeters during the last 20 degrees of terminal extension. When minimal graft excursion is detected, we fix the graft with the knee at 20 degrees of flexion because it is easier to do so at this position. When a larger excursion is detected, we fix the tibial side near full extension. Because of the high fixation strength and stiffness and the resistance to slippage of the IntraFix and Bio-IntraFix, we caution against applying excessive tension (greater than 80N) to the graft and against fixing the knee at a flexion angle greater than 20 degrees. High graft tension results in the graft construct being under tension through a greater range of motion, subjects the graft to higher abrasion forces at the femoral tunnel edge (killer angle) during knee motion, and can overconstrain or “capture” the knee.

Device Insertion Concentric device placement within the tibial tunnel is critical to the success of the technique. To achieve this, the central axis of the tibial tunnel is identified by passing a stout guidewire or a Trailblazer (Smith & Nephew Endoscopy, Andover, MA) through the center of the tie tensioner and down the center of the four graft strands into the knee joint (Fig. 47-5). Once the central axis of the tibial tunnel is identified, the tie tensioner should be held in this orientation during all the subsequent steps to avoid divergent placement of the IntraFix sheath and screw. The surgeon can improve his or her ability to maintain this orientation by placing several fingers or the entire side of the hand holding the tensioner on the tibia during the next steps. Next, the four-quadrant dilator is inserted down the center of the four graft strands and oriented so that each graft strand sits in its own channel (Fig. 47-6). While maintaining the desired tension on the graft, the four-quadrant dilator is tapped into the tibial tunnel for a distance of 35 mm. This step compresses and separates the four tendon strands, and, in the case of smaller tunnels (7 to 8 mm), notches the bone tunnel wall to accept the sheath. It is important to keep the dilator oriented along the axis of the tibial tunnel as it is impacted because the dilator

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener

4.

5

A

–

47

5"

B

FIG. 47-4 A, The use of differently colored sutures on the gracilis and semitendinosus tendons helps with identification during graft tensioning and tibial fixation. B, The sutures are marked between 4.5 and 5 inches from the edge of the tibial tunnel. A hemostat can be used to hold this location during knot tying. The two gracilis suture limbs and the two semitendinosus suture limbs are tied together, creating a suture loop.

has a tendency to diverge, as do most tunnel dilators. Because the sheath for the IntraFix and Bio-IntraFix is 9 mm in diameter, the four-quadrant dilator also enlarges the tibial tunnel in the case of smaller tunnels, providing easier insertion of the IntraFix sheath and tapered screw. There are now two sheaths for the Bio-IntraFix and a smaller and larger dilator appropriate to each. The smaller sheath is used for 7- and 8-mm tunnels and the larger for 9- and 10-mm tunnels. After dilating the tibial tunnel, the 30-mm Intrafix sheath is placed on the sheath inserter with the derotational tab on the sheath oriented to match the tab on the sheath inserter. The knee is positioned at the chosen flexion angle, and a final tension of 60N to 80N is applied to the DGST graft or tibialis tendon allograft using the tie tensioner. The Intrafix sheath is inserted among the four graft strands, taking care that each graft strand is positioned into a separate channel of the IntraFix sheath. The derotational tab on the sheath is oriented at the 3- or 9-o’clock position (Fig. 47-7). Orienting the derotational tab at these positions allows the IntraFix sheath to be inserted more deeply into

the tibia and prevents prominence of the device. The inserter is tapped into the tunnel until the derotational tab is flush with the cortex. As stated earlier, clearing the soft tissue from the bone tunnel opening will allow for better assessment of the depth of insertion and trimming of any protruding tendon or sheath after the screw has been inserted. The sheath inserter is removed, and the 0.042-inch guidewire for the IntraFix tapered screw is inserted through the center of the sheath until a loss of resistance is felt as the tip of the guidewire enters the knee joint. For the plastic IntraFix, a tapered screw size 1 mm larger than the tibial tunnel diameter is used. For example, an 8-mm tapered screw is used for a 7-mm tibial tunnel. Given the typical size of DGST grafts, the 7- to 9-mm tapered screw is most commonly used. The IntraFix screw is inserted into the plastic sheath until its inferior aspect is flush with or buried just below the tibial cortex (Fig. 47-8). Because the best bone quality is at or next to the tibial cortex, overly deep insertion of the screw may decrease fixation strength.24 The tension on the graft

345

Anterior Cruciate Ligament Reconstruction

FIG. 47-5 The resulting suture loop from the gracilis and semitendinosus tendons is looped over the arms of the tie tensioner. The tie tensioner will equally tension and separate each strand of the graft. The central axis of the tibial tunnel is identified by passing a 1.1-mm guidewire through the center of the tie tensioner and down the center of the four graft strands into the knee joint.

strands from the tie tensioner should prevent the sheath from rotating during screw insertion in hard bone, but some rotation of the outer sheath is acceptable because the sheath within the tunnel does not move in concert. Protruding or prominent areas of the polyethylene sheath are trimmed flush with the tibial cortex using a 15 blade and a small bone rongeur. The technique for insertion of the Bio-IntraFix device is identical, but the sizing scheme differs from that just 346

described (Table 47-2). Because the PLLA/TCP sheath is noncompressible and because the insertion torque is higher than with the plastic version, the tunnel should be drilled or dilated 1.0 mm larger than the graft diameter. The BioIntraFix sheath adds more than 1 mm to the diameter of the Bio-IntraFix screw, so in effect the fixation device in total is oversized to the tunnel diameter, which is the usual practice with interference screws and with the plastic IntraFix.

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener

47

FIG. 47-6 Insertion of the four-quadrant trial dilator. The dilator is oriented so that each graft strand is positioned in its own channel. The dilator will separate and compress the tendons while preparing a bony channel for the IntraFix sheath.

The stability and range of motion of the knee are checked. It is important to verify that the patient has full range of motion before leaving the operating room. The arthroscope is inserted into the knee, and graft tension and impingement are assessed. Our usual graft placement and tensioning technique results in the four strands of the DGST being maximally tight between 0 and 20 degrees, with the graft tension decreasing slightly as the knee is flexed to 90 degrees.

Troubleshooting Sheath Overinsertion As with any fixation device, potential errors can be made during the use of the IntraFix device. Overinsertion of the sheath is one such error. This problem typically occurs when a sheath smaller than the tunnel size is driven into the tunnel and the sheath’s advancement is not controlled. When this happens, the opening to the sheath cannot be seen

347

Anterior Cruciate Ligament Reconstruction

FIG. 47-7 Insertion of the 30-mm IntraFix sheath. The knee is positioned at the chosen flexion angle, and the selected tension is applied to the graft using the tie tensioner. The 30-mm IntraFix sheath is inserted down the center of the doubled gracilis and semitendinosus graft, parallel to the axis of the tibial tunnel. The derotational tab on the sheath is positioned at the 3- or 9-o’clock position, with each tendon graft strand positioned in its own channel.

and central placement of the screw cannot be assured. If the sheath is far into the tunnel, screw insertion should be abandoned until the sheath is pulled back into position or removed and another sheath is inserted. Because the ridges on the sheath are slanted to resist slippage of the graft proximally, attempts to grasp the sheath and pull it out of the tibial tunnel are often unsuccessful. Cutting the sheath or

348

blindly grabbing it with an instrument such as a pituitary rongeur can damage the graft strands and the sutures holding them, risking rupture during tensioning. A better method involves pushing the sheath further up the tunnel, together with pulling the graft proximally with a probe inside the joint until the sheath can be seen entering the knee joint. At this point, the sheath can be grasped and

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener

47

FIG. 47-8 Insertion of the IntraFix tapered screw. The selected graft tension is maintained on the graft strands using the tie tensioner, with the knee at the chosen flexion, and the IntraFix tapered screw is inserted along the guidewire into the IntraFix sheath. The IntraFix tapered screw is advanced until the superior edge of the screw is just below the anterior tibial cortex.

removed through one of the portals, usually in pieces. The graft is then retensioned using the tensioner, and the standard steps noted above are repeated.

Screw Breakage With the introduction of the PLLA/TCP Bio-IntraFix, screw breakage has sometimes occurred during insertion. This problem is partly due to the friction between the screw and sheath, which was never a concern with the plastic

IntraFix, and in part because the tunnel may not have been enlarged above the diameter of the graft as recommended. (At the time of this writing, a newer, more robust screw and a sheath with improved properties have been produced, which will make breakage much less likely.) A third factor that can lead to screw breakage is failure to insert the screw along the central axis of the sheath and tunnel. A fourth cause is failure to seat the screwdriver fully within the screw. 349

Anterior Cruciate Ligament Reconstruction TABLE 47-2 Sizing Scheme for IntraFix Graft Diameter

Drill Tunnel

Screw Size

7 mm

7 mm

6–8 mm

8 mm

8 mm

7–9 mm

9 mm

9 mm

8–10 mm

10 mm

10 mm

8–10 mm

When screw breakage happens, it is most often early during insertion, and it is nearly impossible to withdraw the screw tip with the driver due to a lack of purchase. Furthermore, the screw seems to bind within the sheath. The surgeon has two basic options at this point. The first approach is to revise the entire construct. In this case we use an “easy-out” device, such as those marketed to remove stripped cannulated interference screws, and core the screw out from within the sheath. Sometimes a new smaller screw can be inserted in its place and into the same sheath, but more commonly the sheath needs to be replaced. If the smallest of the screws (6 to 8 mm) was used initially, another screw of the same size is likely to suffer the same fate. A better strategy is to remove the sheath with a grasper and then to insert the larger 9-mm dilator more deeply into the tunnel among the graft strands, enlarging the tunnel further. After a new sheath is placed, a new screw should be carefully inserted along the axis of the tunnel. Blood, fatty tissue, or saline can be used to reduce insertion torque and should be tried during screw insertion in such instances, especially if the patient’s bone is hard and if additional tunnel dilation efforts did not seem to enlarge the diameter very much. The second technique, which is less commonly used, is to take the sutures from the tendon ends and tie them down onto a staple or screw distal to the tunnel. This approach can only be recommended if there is a significant length (greater than 50%) of screw within the sheath so that the sheath construct will not collapse when the sutures are tied below and migration of the device will not occur.

Failure to Advance A related screw insertion problem is failure of the screw to advance until it is fully seated. This has primarily been a problem with the Bio-IntraFix. The main cause is a tunnel diameter too small to accommodate the size of the IntraFix or Bio-IntraFix that was chosen. This situation, although quite rare, may be more challenging than screw breakage. The fact that the screw failed to advance almost certainly indicates that the screw has gained good purchase, at least in the distal portion of the tunnel. Therefore if the screw is no more prominent than an external fixation device such as a screw-washer, then it can probably be left in place, 350

although it may require later removal after the graft has healed. If a much longer portion protrudes and it cannot be withdrawn with the screwdriver, then the protruding portion must be removed with a saw; the inserted portion and sheath removed; and a new, more properly sized device inserted.

Low Bone Density The fixation strength of any intratunnel fixation device is dependent on the local bone mineral density. If, during the insertion of the tapered screw, the surgeon subjectively feels that there was low insertion torque, or if the patient has soft bone as assessed during drilling and dilation of the tunnel, then we recommend that supplemental tibial fixation be used.13 Depending on the graft length, the tendons can be stapled below the tibial tunnel opening using one or two small barbed staples (Smith & Nephew Orthopaedics, Memphis, TN). Another method of backup is to tie the sutures around a small nonbarbed staple, a screw and washer, or a tibial fixation post (Smith & Nephew Endoscopy).

Too Short a Graft Finally, the surgeon may be faced by a graft that is not long enough and with ends that are recessed in the tunnel. If the graft is recessed to the degree that identification of the individual strands is not possible, then concentric placement of the sheath becomes much more difficult. One could try to separate the strands blindly, but then insertion of the dilator runs the risk of rupturing the sutures, with loss of ability to tension. In this case, therefore, it is probably best to tie the sutures onto a fixation post or use an interference screw as the sole means of fixation, or to use a hybrid of the two methods.

Closure and Postoperative Dressings A Hemovac drain can be inserted under the sartorius fascia and into the hamstring harvest site to prevent postoperative hematoma formation and decrease subcutaneous skin ecchymosis along the medial side of the knee.25 This is particularly useful when excessive bleeding is encountered during the hamstring tendon harvest. The sartorius fascia that was preserved during the hamstring tendon graft harvest is closed over the tibial hardware and repaired back to the tibia with a #0 absorbable suture. The subcutaneous tissue is closed in layers with fine absorbable sutures. A running #3–0 Prolene (Ethicon, Sommerville, NJ) subcuticular pullout suture or #4–0 Monocryl produces a very cosmetic closure. A light dressing is applied over the wound, followed by a thigh-length TED antiembolism stocking (Cryocuff, Aircast, Summit, NJ) and knee immobilizer.

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener

POSTOPERATIVE MANAGEMENT The procedure is routinely performed as an outpatient procedure. If a Hemovac drain is used, the drain is removed when the patient is discharged from the day surgery unit. We allow unrestricted motion and weight bearing as tolerated. Early flexion performed as heel slides is encouraged because it prevents scarring of the extensor mechanism. The weight-bearing schedule is modified if a meniscus repair, microfracture, or other associated ligamentous surgery has been performed. The patient is weaned from the knee immobilizer when quadriceps control is regained. Crutches are continued until the patient has regained a normal gait pattern. Riding a stationary bike can be started when the patient has at least 100 degrees of flexion. Closed chain strengthening exercises using a leg press machine, elliptical cross-trainer, StairMaster, and step-ups are started around 4 to 6 weeks after surgery. During the first 3 months after surgery, the hamstring donor site must be protected by avoiding sudden hamstring stretching with the hip and knee in extension. This position is commonly encountered during activities of daily living such as bending down to tie shoes or put on socks or reaching down to pick an object off the floor. We also recommend that isolated hamstring resistive exercises performed in the prone position be avoided for the first 2 to 3 months. Isolated hamstring strengthening exercises using a seated leg curl machine can usually be started after 6 to 8 weeks if tenderness is not present or is minimal at the hamstring donor site. We allow jogging and running at 3 to 4 months, side-to-side cutting at 4 to 5 months, a return to noncontact sports at 5 to 6 months, and a return to unrestricted sports at 6 to 7 months. In revision cases, we recommend that a return to unrestricted sports be delayed until 9 months.

RESULTS We report the preliminary results of the first 84 patients operated on by Dr. Joseph H. Sklar using a DGST graft with Endobutton-CL femoral fixation and tibial fixation with the IntraFix tibial fastener. The mean age of the patients was 30 years (range 16–54 years). Of the patients, 46 were male and 38 were female. The mean diameter of the DGST graft for all patients was 8.3 mm (range 7–9.5 mm) and 7.9 mm for females. The mean KT-1000 side-to-side difference for all patients at the 12-month follow-up was 1.8 mm, with 83% having a side-to-side difference of 0 to 3 mm; 13%, 3 to 5 mm; and 3%, greater than 5 mm. At the 24-month follow-up, the mean KT-1000 side-to-side difference was 1.78 mm, with 85% having a side-to-side difference of 0 to

47

3 mm; 11%, 3 to 5 mm; and 4%, greater than 5 mm. For female patients, the mean KT-1000 side-to-side difference was 2.3 mm, with 80% having a side-to-side difference of 0 to 3 mm; 20%, 3 to 5 mm; and no patient had a difference greater than 5 mm. Supplemental tibial fixation was used in 17% of the male patients and 42% of the female patients. There were no postoperative infections in the group, and no patient had a loss of extension. Flexion averaged 138 degrees at 24 months. Two patients required an early manipulation under anesthesia to regain flexion. No patient has required a second operation to remove prominent hardware.

CONCLUSION In summary, the IntraFix and Bio-IntraFix devices provide strong rigid tibial fixation that is superior to the fixation properties of interference screws and most external fixation methods. The device grips each of the graft strands in its own separate compartment and increases the amount of graft in direct contact with the cancellous bone of tunnel, potentially increasing the amount of bone–tendon healing. Successful use of the device depends on proper tunnel preparation and sizing and the concentric insertion of the device parallel to the axis of the tunnel. In cases in which doubt exists about the hardness of the bone, the IntraFix and Bio-IntraFix can be used in combination with cortical backup fixation.

References 1. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. J Bone Joint Surg 2004;86A:2143–2162. 2. Brand JC, Weiler A, Caborn DNM, et al. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 3. Brown CH, Sklar JH. Endoscopic anterior cruciate ligament reconstruction using quadrupled hamstring tendons and Endobutton femoral fixation. Tech Orthop 1998;13:281–298. 4. Brown CH, Wilson DR, Hecker AT, et al. Graft-bone motion and tensile properties of hamstring and patellar tendon anterior cruciate ligament femoral graft fixation under cyclic loading. Arthroscopy 2004;20:922–935. 5. Cooper DE, Deng XH, Burstein AL, et al. The strength of central third patellar tendon graft. A biomechanical study. Am J Sports Med 1993;21:818–824. 6. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 7. Ahmad CS, Gardner TR, Groh M, et al. Mechanical properties of soft tissue femoral fixation devices for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:635–640. 8. Brown CH, Sklar JH. Endoscopic anterior cruciate ligament reconstruction using doubled gracilis and semitendinosus tendons and Endobutton femoral fixation. Oper Tech Sports Med 1999;7:201–213.

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Anterior Cruciate Ligament Reconstruction 9. Brand JC, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 10. Steiner ME, Hecker AT, Brown CH, et al. Anterior cruciate ligament graft fixation: comparison of hamstring and patellar tendon grafts. Am J Sports Med 1994;22:240–242. 11. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 12. Jansson KA, Harilainen A, Sandelin J, et al. Bone tunnel enlargement with anterior cruciate ligament reconstruction with hamstring autograft and Endobutton fixation technique. Knee Surg Sports Traumatol Arthrosc 1999;7:290–295. 13. Goble EM, Downey DJ, Wilcox TR. Positioning of the tibial tunnel for anterior cruciate ligament reconstruction. Arthroscopy 1995;11:688–695. 14. Kousa P, Jarvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 15. Howell SM. Roof impingement of ACL grafts: diagnosis, cause, prevention, and late surgical correction. In Feagin JA (ed). The crucial ligaments. New York, 1994, Churchill Livingstone, pp 637–648. 16. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadrupled semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83B:348–354. 17. Howell SM. Principles for placing the tibial tunnel and avoiding roof impingement during reconstruction of a torn anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 1998;6:S49–S55. 18. Howell SM, Clark JA. Tibial tunnel placement in anterior cruciate ligament reconstructions and graft impingement. Clin Orthop 1992;283:187–195. 19. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg 1993;75A:1044–1055. 20. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel positions. Arthroscopy 2003;19:297–304. 21. Jackson DW, Gasser SI. Tibial tunnel placement in ACL reconstruction. Arthroscopy 1994;10:124–131. 22. Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg 2003;85A:1018–1029. 23. Hamner DL, Brown CH, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg 1999;81A:549–557. 24. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev 1991;20:1085–1088. 25. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex: a biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497.

Suggested Readings Breitfuss H, Frohlich R, Povacz P, et al. The tendon defect after anterior cruciate ligament reconstruction using the mid third patellar tendon—a

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problem for the patellofemoral joint? Knee Surg Sports Traumatol Arthrosc 1996;3:195–198. Brown CH, Sklar JH, Darwich N. Endoscopic anterior cruciate ligament reconstruction using autogenous doubled gracilis and semitendinosus tendons. Tech Knee Surgery 2004;3:215–237. Butler DL. Evaluation of fixation methods in cruciate ligament surgery. AAOS Instruct Course Lect 1987;36:173–178. Ejerhad L, Kartus J, Sernert N, et al. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with two-year follow-up. Am J Sports Med 2003;31:19–25. Harvery AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four-stranded hamstring grafts for anterior cruciate ligament reconstruction. Knee 2002;10:97–102. Hill PF, Russell VJ, Salmon LJ, et al. The influence of supplementary tibial fixation on interior laxity measurements after anterior cruciate ligament reconstruction with hamstring tendons in female patients. Am J Sports Med 2005;33:94–101. Howell SM, Clark JA, Farley TC. A rationale for predicting anterior cruciate graft impingement by the intercondylar roof: an MRI study. Am J Sports Med 1991;19:276–281. Howell SM, Gittens ME, Gottlieb JE, et al. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. Jannson KA, Linko E, Sandelin J, et al. A prospective randomized study of patellar versus hamstring tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:12–18. Karahan M, Erol B, Bekiroglu N, Uyan D. Effect of drain placed in the donor site in the early postoperative period after arthroscopically assisted cruciate ligament reconstruction with quadrupled hamstring tendons. Am J Sports Med Preview 2005;33:900–906. Kartus J, Magnusson L, Stener S, et al. Complications following arthroscopic anterior cruciate ligament reconstruction. A 2–5 year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc 1999;7:2–8. Kartus J, Movin T, Karlsson J. Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts. Arthroscopy 2001;17:971–980. Laxdal G, Kartus J Hannson L, et al. A prospective randomized comparison of bone-patellar tendon-bone and hamstring grafts for anterior cruciate ligament reconstruction. Arthroscopy 2005;21:34–42. Levy M, Prudhomme J. Anatomic variations of the pes anserinus: a cadaver study. Orthopedics 1993;16:601–606. Levy M. Surgical technique for harvesting the gracilis and semitendinosus tendons. Contemp Orthop 1993;26:369–372. Muneta T, Yamamoto H, Ishibashi T, et al. The effects of tibial tunnel placement and roofplasty on reconstructed anterior cruciate ligament knees. Arthroscopy 1995;11:57–62. Pagnani MJ, Warner JJ, O’Brien SJ, et al. Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565–571. Pinczewski LA, Deehan DJ, Salmon LJ, et al. Five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:523–535. Romano VM, Graf BK, Keene JS, et al. Anterior cruciate ligament reconstruction: the effect of tibial tunnel placement on range of motion. Am J Sports Med 1993;21:415–418. Soloman CG, Pagnani MJ. Hamstring tendon harvesting. Reviewing anatomic relationships and avoiding pitfalls. Orthop Clin North Am 2003;34:1–8.

Hamstring Anterior Cruciate Ligament Reconstruction with IntraFix Tibial Fastener Warren LF, Marshal JL. The supporting structures and layers on the medial side of the knee. J Bone Joint Surg 1979;61A:56–62. Woo SL-Y, Hollis JM, Adams DJ, et al. Tensile properties of the human femur-anterior cruciate ligament-tibia complex. The effect of specimen age and orientation. Am J Sports Med 1991;19:217–225. Yamamoto Y, Hsu W-H, Woo SL-Y, et al. Knee stability and graft function after anterior cruciate ligament reconstruction. A comparison of a

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lateral and an anatomical femoral tunnel placement. Am J Sports Med 2004;32:1825–1832. Yasuda K, Onkoshi Y, Tanabe Y. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med 1994;23:705.

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48 CHAPTER

Gene R. Barrett Taylor D. Brown

PART H BONE–PATELLAR TENDON–BONE FIXATION: FEMUR OR TIBIA

Interference Screw Fixation in Bone– Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction INTRODUCTION Interference screw fixation on both the femoral and tibial sides remains an effective fixation scheme for bone–patellar tendon–bone (BPTB) anterior cruciate ligament reconstruction (ACLR). Interference screws achieve early stability with aperture fixation and a rigid fixation of graft to host bone. Interference screw fixation of BPTB ACLR provides strength greater than that needed during early rehabilitation.1–3 This chapter includes our ideas and techniques for maximizing the potential for early stability with interference screw fixation of BPTB ACLR.

GRAFT PREPARATION In order to visualize our fixation strategies, the reader should have an understanding of the shape of our graft. Through a slightly medial parapatellar incision, the peritenon of the patella tendon is elevated and the tendon is visualized from its medial to lateral border. We use a ruler not only to confirm the tendon to be 30 to 33 mm in width, but also to measure the distance between longitudinal cuts through the full thickness of the patella tendon 10 to 11 mm apart. We use a combination of an oscillating saw and osteotomes to harvest a trapezoidalshaped bone block from the tibial tubercle, which is 25 to 27 mm long, and a triangularshaped bone block from the patella, which is 25 mm long (Fig. 48-1). The bone blocks are trimmed with a rongeur to pass through either 354

a 10- or 11-mm sizing sleeve. The overall length of the graft is usually 90 to 105 mm. Two stay sutures are passed through each bone block and tendon using #1 absorbable monofilament (PDS) for the femoral block and #5 nonabsorbable braided suture for the tibial end of the graft. The absorbable suture in the femoral bone block allows us to cut the suture flush with the skin if it will not pull out. The bone block with the better bone, which is usually the tibial tubercle block, is directed toward the femoral canal with the #1 sutures (PDS). The graft is stretched on a graft board with 20 pounds of tension for 10 to 15 minutes while covered by an antibiotic-soaked gauze (Fig. 48-2).

SCREW SELECTION A cannulated, round-headed, partially threaded screw is used for the femoral side to protect the graft from laceration at the bone plug– tendon interface. Any number of manufacturers produce round–headed, partially threaded screws.4 A fully threaded screw or a screw with a squared-off head may put the tendinous portion of the graft at risk. We use a fully threaded screw for fixation in the tibial tunnel. The extra threads provide additional fixation, and a round head is not needed distal to the screw and graft. The literature has shown that the effect of screw diameter is interrelated to the tunnel diameter and the gap size between the graft bone plug and tunnel.5–7 We make our tunnels the same size as the sizers through which our

Interference Screw Fixation in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction

Tibial bone

48

Patellar bone

10–11 mm

9–10 mm 25–27 mm

45–50 mm

25 mm

FIG. 48-1 Bone–patellar tendon–bone suture configuration (absorbable suture in tibial bone and permanent in patellar bone).

use a plastic sheath to protect both the ACL graft and native posterior cruciate ligament (PCL) when inserting both metal and bioabsorbable screws into the notch and femoral tunnel (Fig. 48-3, A and B). Bioabsorbable screws were introduced as a device to provide secure mechanical fixation in the interval prior to biological fixation of the graft and then leave the body with

FIG. 48-2 PDS and permanent suture in a graft that is being loaded.

graft bone plugs pass, usually 10 or 11 mm. In both the femoral and tibial tunnels, our first choice for screw diameter is 1 mm less than the tunnel diameter for metal screws, usually 9 or 10 mm, and the same as the tunnel diameter for bioabsorbable screws, usually 10 or 11 mm. Length of interference screws has not been correlated to fixation strength with BPTB grafts.8–10 We try to match the length of the screw to the length of the graft bone plug. If the surgeon harvests a full 25 mm of bone plug and makes a tunnel deep enough to accommodate the whole plug, he or she should fix the full length of the plug within the tunnel. We frequently use 25-mm-long metal or 28-mm-long bioabsorbable screws in the femoral tunnel, and we use 25-mm-long metal or 28-mm-long bioabsorbable screws in the tibial tunnel. Metal interference screws have a proven track record for secure fixation of BPTB ACLR and are well tolerated by the human body. However, complications related to this hardware option include laceration of the graft on insertion and interference with postoperative magnetic resonance imaging (MRI) scans of the knee, as well as potentially blocking tunnels for revision ACLR. The influence on MRI has been lessened with the use of titanium screws compared with the stainless steel screws initially used. Graft laceration by the screw has not been a problem because we

FIG. 48-3 A, Graft protector for screw insertion. B, The plastic sheath protects the graft from laceration.

355

Anterior Cruciate Ligament Reconstruction no residual foreign material. They create less interference with MRI scans of the knee, cause less graft trauma, and allow easier revision by disappearing or by just drilling through any remnant. The disadvantages of these implants were reported to be breakage and soft tissue reaction due to poor biocompatibility. Poly-L-lactic acid (PLLA) screws are most commonly used today. Studies have shown screw breakage on insertion to be uncommon and, when it does occur, does not cause adverse effects.11,12 A handful of cases of late screw fragmentation have been reported, and soft tissue reactions to PLLA are rare.13,14 The low rate of soft tissue reactions to PLLA is due to the slow rate of degradation in vivo. Studies show persistence of these screws years after insertion.15,16 The tensile strength of cancellous and cortical bone is less than that for titanium or PLLA. For metal and bioabsorbable screws of the same size and shape in the same anatomical and biological scenario, the failure strength will be the same because the construct will fail at the weaker cancellous bone first.3 No significant difference was found when metal and bioabsorbable interference screws in BPTB ACLR were compared with regard to initial strength of fixation as tested with single load and cycle load to failure (LTF).1–3,17,18 Walton showed no difference during a period of interval healing when examining sheep specimens 4 to 52 weeks after interference screw fixation in BPTB ACLR.19 McGuire et al and Kaeding et al showed no significant difference of motion, laxity, or instability between metal and bioabsorbable interference screw fixation of BPTB ACLR as much as 2.4 years postoperatively.11,12

BONE TUNNEL PREPARATION Much has been written to describe proper tunnel placement in both the tibia and lateral femoral condyle. We use a targeting guide for the tibial tunnel with the goal of the guidewire exiting in the posterior portion of the native ACL footprint, just medial to the anterior horn of the lateral meniscus, centered medial to lateral between the tibial spines. The graft harvest incision is retracted medially to place the distal entry site halfway between the anterior cortical ridge and the medial border of the tibia. We use a guide set at 55 degrees to create a tibial tunnel 50 to 55 mm long. After placing the guidewire, we use intraoperative fluoroscopy to confirm the position of the guidewire within the tibia. On the initial flexed lateral image, the guidewire penetrates the proximal cortex of the tibia with approximately 20% to 40% of the anteroposterior length anterior to the guidewire. A second lateral fluoroscopic image is obtained with the knee fully extended. A line extended from the guidewire should be just posterior to Blumensaat’s line (Fig. 48-4). The guidewire is removed 356

FIG. 48-4 Use of a tibial pin to check impingement.

and repositioned if it does not meet the just-mentioned criteria. Once the guidewire is positioned appropriately and no impingement is confirmed, the first reamer, which is 2 mm smaller than the graft size and final tunnel diameter, is passed. Bone reamings are collected to use as autograft for the patella–bone plug defect at the conclusion of the case. The tibial tunnel is then expanded incrementally 2 mm up to the final diameter. The femoral tunnel is placed on the medial aspect of the lateral femoral condyle with just 1 to 2 mm of cortical bone posterior to the tunnel.20–22 A 5-mm offset femoral guide is used transtibially for femoral tunnel placement (Fig. 48-5). The knee must be flexed to a position such that the guidewire is not directed posteriorly to exit the posterior portion of the femur. The guidewire is placed using the offset guide. The position just anterior to the posterior wall is confirmed on a true lateral fluoroscopic image of the distal femur. A small, 7- or 8-mm acorn reamer is passed to a depth of 35 to 40 mm after proper guidewire position is confirmed. The guidewire is repositioned in the anterior portion of the femoral tunnel and gently tapped into the depth of the tunnel to secure it in a slightly anterior eccentric position within the femoral tunnel. Progressively larger reamers or dilators are used to enlarge the tunnel to its final diameter and avoid posterior wall blowout. A motorized shaver is introduced through the anteromedial portal to remove all loose bone-reaming debris from the posterior joint space and notch. A rasp is placed through the tibial tunnel and up into to the femoral tunnel to confirm

Interference Screw Fixation in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction

48

RELATIVE POSITION OF SCREW AND GRAFT WITHIN TUNNEL

FIG. 48-5 Pin placement for femoral tunnel.

posterior wall by palpation and then to rasp smooth the anterior aperture of the femoral tunnel (Fig. 48-6). The arthroscope is then removed from the anterolateral portal and inserted through the tibial tunnel, across the knee joint, and into the femoral tunnel to visually check continuity of the posterior wall. The knee is hyperflexed, and a Beath pin is placed through both tunnels and the femoral cortex to exit the anterior thigh. The Beath pin then brings a passing suture loop across the knee, and the passing suture loop is used to bring the leading graft sutures through the knee to exit the anterior thigh. The graft is brought into the knee.

FIG. 48-6 Rasp used to smooth the anterior edge of the femoral hole.

The femoral tunnel is placed on the medial aspect of the lateral femoral condyle with just 1 to 2 mm of cortical bone posterior to the tunnel.20–22 A 5-mm offset femoral guide is used transtibially for femoral tunnel placement. A small (8mm) acorn reamer is used followed by progressively larger reamers to avoid posterior wall blowout. The tendinous portion of the graft does not fill the aperture of the femoral tunnel, so its relative position within the tunnel can be directed. A soft tissue grasper is inserted through the anteromedial portal and used to rotate the graft bone plug prior to its final entry within the femoral tunnel. We place the cortical side of the bone plug in the posterolateral aspect of the femoral tunnel, placing the tendinous portion of the graft at the posterolateral portion of the aperture. The guidewire and screw are placed opposite the graft in the anteromedial portion of the tunnel (Fig. 48-7, A and B). With regard to depth within the tunnel, the graft bone plug is usually recessed 1 to 2 mm within the femoral tunnel and the interference screw is placed with the head flush with the distal end of the graft bone plug, with no hardware overhanging the graft bone plug to abrade the tendon (Fig. 48-8, A and B). Prior to inserting the graft within the knee, we use a rasp to smooth the anterior lip of the femoral tunnel opening. The depth that the tibial bone plug comes to rest within the portion of the tibial tunnel is dictated by the length of the graft and the position in which the femoral bone plug was fixed. There are choices with regard to the rotation of the cortical-cancellous surfaces and the surfaces for healing versus fixation. We choose to rotate the graft bone plug so that the cortical surface comes to lie anteriorly within the tibial tunnel, and we place the tibial interference screw anterior to the graft bone plug (Fig. 48-9). Rupp et al tested bone plugs and found no difference in initial fixation strength when the screw was placed in either the cortical or the cancellous surfaces of the graft bone plug.23 However, the bone density of the proximal tibial metaphysis is lower than that of the distal femur, and we want to place the interference screw between the harder cortical surface of the graft and the harder anterior cortex of the anterior tibia, similar to a wedge.24 Furthermore, this places the cancellous portion of the graft bone plug next to the cancellous bone of the tibial tunnel to facilitate bone–bone healing. Yoshiya et al demonstrated incorporation of the bone plug at the bone– bone interface at 12 weeks when the cancellous portion of the bone plug was placed next to the bone tunnel and the interference screw was placed at the cortical side of the bone plug.25

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Anterior Cruciate Ligament Reconstruction

Guidewire

A FIG. 48-7 A, Pin position prior to femoral screw insertion. B, X-ray confirmation of pin placement prior to screw insertion.

A FIG. 48-8 A, Screw parallel to and the same length as the bone block. B, Parallel screw placement by x-ray.

358

Interference Screw Fixation in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction

FIG. 48-9 X-ray demonstrating femoral/tibial fixation.

PARALLELISM AND DIVERGENCE The goal with femoral interference screw insertion is parallelism. This is desired to accomplish one of the stated benefits of this graft choice: early rigid fixation. Initial rigid fixation allows early weight bearing, early motion, and an accelerated rehabilitation program. This goal can be accomplished when both the femoral tunnel reaming and femoral interference screw insertion occur through the same path. Three options meet this criterion. Early anatomical ACLR used a distal lateral thigh exposure for a two-incision reconstruction. The femoral tunnel was drilled from outside-in, and the interference screw followed. With or without a guidewire, the interference screw could reliably be positioned parallel to the tunnel and bone block. Lemos et al reported 0 of 25 cases to have divergence with this technique.26 Cerullo and Puddu described using an arthroscope to view directly down the femoral tunnel from the outside to confirm parallel position of the femoral screw within the femoral tunnel, and he stated it could be done as well in the tibial tunnel.27 We frequently resort to this two-incision technique if we are doing a revision or have a long graft (greater than 105 mm) and a graft–tunnel mismatch. One-incision, arthroscopic-assisted ACLR is more commonly performed today, and most femoral tunnels today are guided by wires through tibial tunnels and reamed through those same tibial tunnels. In a manner similar to that described by Paulos, Brodie et al inserted the femoral screw into the joint through an anteromedial portal, but screw insertion into the femoral canal was carried out with

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the screwdriver passing anterior to the distal bone plug in the tibial tunnel, parallel to the path taken by the femoral canal reamers. No patient had screw/tunnel divergence greater than 15 degrees in either plane.28 Schroeder showed only 4% divergence when passing a 7-mm interference screw and driver through the tibial tunnel, tapping the distal bone plug as it passed, into the parallel femoral tunnel.29 A third option involves both reaming and placing the femoral screw through an anteromedial portal with the knee in a hyperflexed position. Despite the fact that at present most femoral tunnels are reamed through a tibial tunnel, most femoral interference screws are placed through an anteromedial portal. Although parallelism is the goal, divergence of the femoral screw and tunnel results can be made acceptable. Efforts to minimize this divergence are made, as biomechanical studies have shown little difference in the pullout strength when divergence is less than 15 degrees as compared with parallel, but pullout strength is much lower when divergence is greater than 15 degrees.30–32 In addition to the poor initial fixation, divergence can also cause intraoperative complications such as guidewire bending, guidewire breakage with inadvertent hardware retention, or graft bone block fracture.33 We use several techniques to minimize our femoral screw/tunnel divergence. The graft has already been passed, and the femoral bone block rests within the femoral tunnel. We establish an accessory anteromedial portal, which is placed lower than a traditional anteromedial portal and just medial to the border of the patellar tendon. No additional skin incision is needed, and the arthrotomy for this portal is carried out through the already open anterior incision for patella tendon harvest. At this point the knee is taken to a position of deeper flexion than that with which the femoral tunnel was drilled. We have not found our arthroscopic visualization of the opening of the femoral tunnel to be limited by this change in position. Initially, a rigid “trailblazer” is passed through this portal and up into the anterior portion of the femoral tunnel, just anterior to the graft, in an effort to make an opening for the first few threads of the interference screw to be placed later. This accomplishes the same result as passing a few threads of a tap. Then a guidewire is inserted through this same portal, across the femoral notch, and into the femoral tunnel anterior to the graft bone plug. The guidewire can be felt to slide effortlessly within the femoral tunnel. At this point a sterile draped fluoroscopy unit is brought within the operative field, and the position of the guidewire within and parallel to the femoral tunnel and bone block is confirmed on lateral fluoroscopic images. Rodin and Levy have published a similar technique, with only 3% of the 62 cases having significant divergence greater than 15 degrees.34 Finally, we ensure that the guidewire remains freely mobile during screw insertion to prevent guidewire bending or 359

Anterior Cruciate Ligament Reconstruction breakage, with some similarities to the advancing guidewire technique as described by Ha et al.33 We remove the guidewire prior to completing the last few turns of the screw within the femoral tunnel. If for some reason the screw does not insert appropriately, or if the wire is bending or the screw is divergent, the screw can be removed, the guidewire can be repositioned or replaced if bent, and the same-size screw can be reinserted to achieve the same fixation pullout strength as a screw inserted only once.35

GRAFT–TUNNEL MISMATCH Graft–tunnel mismatch is a problem unique to endoscopic single-incision BPTB ACLR. This term includes any situation in which the location of the tibial tunnel bone plug makes placing the tibial tunnel interference screw difficult or impossible. This is a well-recognized problem, and numerous publications have presented alternatives to prevent or deal with graft–tunnel mismatch. Shaffer et al and Olszewski et al report techniques to prevent mismatch using intraoperative measurements and simple mathematical equations to direct the length of tibial tunnel required prior to creating that tunnel.36,37 The tibial guide used in this technique provides a measurement of the length of the tibial tunnel prior to the tunnel being drilled. Central to these ideas is that the length of the tibial tunnel and intraarticular distance must be greater than or equal to the length of the patella tendon and tibial bone plug in order for the tibial bone plug to come to rest within the tibial tunnel. The tibial tunnel length is the only nonanatomical variable. With a long patella tendon, these formulas would suggest a long tibial tunnel with a high angle down the tibial shaft. Angles in excess of 60 degrees are not practical because they disrupt the pes anserina and make creation of femoral tunnels difficult to achieve without blowing out the posterior cortex.37 Others recommend always using a standard tibial tunnel angle of 55 degrees, creating a tunnel length of 50 to 55 mm, and being satisfied that this will work in the majority of cases.20,38 Options for dealing with the problem after the femoral and tibial tunnels have been created have been described as well, including recessing the femoral bone plug deeper within the femoral tunnel, rotating the graft along its long axis to shorten the length of the patella tendon, flipping the tibial bone plug back onto the tendinous portion of the graft, and achieving alternative tibial fixation.39–41 Staples or suture posts can be used when solid fixation with interference screws cannot be achieved.

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Our technique for preventing graft–tunnel mismatch includes preoperative assessment of the lateral radiograph for patella alta or baja. We harvest our graft and measure its total and tendinous lengths prior to creating tunnels. Our grafts are usually 90 to 105 mm in length, with the patella tendon usually 40 to 55 mm in length. Reported mean lengths of patella tendons range from 43 to 48 mm, with outer limits including tendons of 33 to 63 mm.36–38 Graft–tunnel mismatch is more frequent with patella tendon length greater than 50 mm.36 When our total graft is longer than 105 mm, we will frequently plan for a twoincision technique and create our femoral tunnel using an outside-in fashion. With a two-incision technique, bitunnel interference screw fixation is not a problem, as the total tunnel length is usually 120 mm.36,42 Otherwise, we proceed with standard tunnel placement and preparations. We drill a tibial tunnel with a 55-degree angle, drill the femoral tunnel through the tibial tunnel, confirm femoral guidewire placement with fluoroscopy, and prepare a femoral tunnel 35 to 40 mm deep. The anterior edge of the femoral tunnel is rasped smooth, and the posterior wall is palpated to ensure integrity. The graft is passed into the femoral tunnel, with the femoral bone plug recessed 1 or 2 mm from the aperture. The graft is fixed at this position if the tibial bone plug rests within the tibial tunnel. Our first step for mismatch if the tunnels have already been created is to recess the graft 5 to 10 mm within the femoral tunnel. As with all femoral interference screws that we place, we confirm parallelism with fluoroscopic images of the guidewire prior to screw insertion to a recessed femoral bone plug. If the tibial bone plug protrudes from the tibial tunnel after 10 mm of femoral recession, we have two other options. If the tibial bone plug is longer than the femoral bone plug, the graft can be reversed so that with the new bone–tendon margin recessed 10 mm in the femoral tunnel, the new tibial bone plug is shorter in length and may be contained entirely within the tibial tunnel. If all these efforts have failed, we will deepen the distal posterior aspect of the tibial tunnel with a rongeur and bur to inlay the tibial bone plug and capture it with a staple. Mismatch with too short a graft is uncommon because intraarticular distance between the tunnel apertures ranges from 20.4 to 26 mm, whereas the mean lengths of patella tendons range from 43 to 48 mm.36–38 If the graft is short and the tibial bone plug comes to rest deep within the tibial tunnel and near the articular surface, we confirm placement of the guidewire past the tibial bone plug and into the joint with arthroscopic visualization. We also confirm that the screw is not placed too deep within the joint

Interference Screw Fixation in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction with the arthroscope. In this situation, a Hewson Ligament Button can be used as backup cortical fixation.

EXTREMES OF BONE DENSITY The easier extreme to accommodate is hard, young bone. The first reamer we use in both the tibial and femoral tunnels is usually 2 mm less than the desired diameter. For normal or hard bone, we will use standard powered reamers to increase the tunnel diameter up to the desired size in 1-mm increments. Prior to placing the screws in hard bone, we will use a metal tap to tap threads for the incoming screw into both tunnels. Even with hard bone, the usual screw diameters will be placed. Softer bone can be more problematic, and thus more options are available. As stated, our initial reamer is 2 mm smaller than our final tunnel diameter. If the bone feels soft in the work leading up to this point, we will use serial dilators in 0.5-mm increments to increase the size of the tunnel and compact the bone surrounding the tibial tunnel. A tap is not used prior to inserting the screws. Decreased bone mineral density has been shown to be correlated with decreased insertional torque and failure load.5,24,43 Even without a torque wrench, the surgeon’s own forearm can indicate a difference in insertional torque in soft bone. With soft bone, our choice for screw diameter will be 1 mm greater than usual with normal bone—the same as the tunnel diameter for metal screws, usually 10 or 11 mm—and 1 mm greater than the tunnel diameter for bioabsorbable screws, usually 11 or 12 mm for a 10- or 11-mm tunnel. However, patients with soft bones frequently have a smaller patella tendon and we frequently harvest a 9-mm graft, making the tunnels 9 mm, and the screws are 9 mm for metal and 10 mm for bioabsorbable. If the surgeon and his or her own forearm do not believe that the first screw placed has enough insertional torque, then the screw should be removed and replaced with a screw 1 mm larger in diameter. This can be repeated a second time, but if the fixation is poor at this point, other fixation strategies must be considered. Our backup femoral fixation in cases of poor interference screw fixation or posterior wall blowout is Endobutton fixation (Acufex, Smith & Nephew, Mansfield, MA). The graft is removed from the knee in the case of poor screw fixation and prepared by connecting the Endobutton to the graft bone plug with two or three loops of #5 nonabsorbable braided suture passed through drill holes in the bone plug and woven through the tendinous portion of the graft. The femoral tunnel is prepared by passing the last reamer through the femoral tunnel all the way to but not through the lateral cortex of the femur. A 2.4-mm guidewire and

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then a 4.5-mm reamer are passed through the lateral cortex of the femur. Leading and trailing sutures are placed in the peripheral holes of the Endobutton. The graft is placed in the knee. The Endobutton is led out of the 4.5-mm opening in the lateral cortex and then deployed by tugging on the trailing suture. The graft is tensioned with sutures in the opposite end of the graft to confirm deployment of the Endobutton and secure fixation of the femoral end of the graft. The position of the Endobutton is further confirmed with anteroposterior and lateral fluoroscopic images. An interference screw can be placed in the femoral canal in the standard fashion if additional fixation is desired.44 Our preferred backup on the tibial side is a Hewson ligament button placed over the distal opening of the tibial tunnel under a periosteal flap. The #5 nonabsorbable braided sutures attached to the tibial bone plug and distal graft tendon are led through separate openings in the button. A posterior drawer moment is placed about the knee with the knee in approximately 60 degrees of flexion. The sutures are tensioned as appropriate, and the knee is passed through 20 rotations of range of motion and then tied over the button. The periosteal flap is then closed over the button. The button technique allows good cortical bone fixation as a backup to soft bone.44 Additionally, a suture post technique with nonabsorbable sutures tied over a screw and washer can be used. If this is used as a backup for femoral fixation, a separate second incision centered over the distal lateral thigh will be necessary to place the screw in the distal femur. All three of these femoral fixation techniques have been shown to have no difference in ultimate failure load.45 Another form of “soft” bone occurs with graft bone block fracture. This can occur intraoperatively during screw insertion or postoperatively during rehabilitation or repeat injury.46 When the femoral bone block is fragmented, the graft can be reversed and the patellar bone block can be inserted and fixed within the femoral tunnel. The opposite tendinous portion of the graft can be captured with nonabsorbable suture and then tied over a button or post on the tibia. If the tibial bone plug fractures, a similar scenario without the graft reversal can be attempted. If these techniques do not achieve a stable knee, the remaining options include obtaining a new autograft from another source (e.g., quadriceps, hamstring) or using an allograft to complete the ACLR.

CONCLUSION Although interference screw fixation has definite advantages, allowing early range of motion and more aggressive earlier rehabilitation, it is a very “unforgiving” construct. 361

Anterior Cruciate Ligament Reconstruction Meticulous attention to detail is paramount to a good outcome. Graft harvest must be carefully carried out without cracking the patella or the bone plug. Great care must be used to ensure that tunnel placement is as anatomical as possible. Attention to graft positioning in the tunnels and care during screw insertion to avoid graft laceration and bone block fracture are needed for good results. Fluoroscopic visualization can be used at any time to confirm positioning of tunnels or screws. A satisfactory result depends on attention to detail and is a matter of millimeters.

References 1. Caborn DN, Urban WP Jr, Johnson DL, et al. Biomechanical comparison between BioScrew and titanium alloy interference screws for bone-patellar tendon-bone graft fixation in anterior cruciate ligament reconstruction. Arthroscopy 1997;13:229–232. 2. Rupp S, Seil R, Schneider A, et al. Ligament graft initial fixation strength using biodegradable interference screws. J Biomed Mater Res 1999;48:70–74. 3. Beevers DJ. Metal vs. bioabsorbable interference screws: initial fixation. Proc Inst Mech Eng [H] 2003;217:59–75. 4. Bach BR. Observations on interference screw morphologies. Arthroscopy 2000;16:E10. 5. Brown GA, Pena F, Grontvedt T, et al. Fixation strength of interference screw fixation in bovine, young human, and elderly human cadaver knees: influence of insertion torque, tunnel-bone block gap, and interference. Knee Surg Sports Traumatol Arthrosc 1996;3:238–244. 6. Shapiron JD, Jackson DW, Aberman HM, et al. Comparison of pullout strength for seven- and nine-millimeter diameter interference screw size used in anterior cruciate ligament reconstruction. Arthroscopy 1995;11:596–599. 7. Kohn D, Rose C. Primary stability of interference screw fixation. Am J Sports Med 1994;22:334–338. 8. Black KP, Saunders MM, Stube KC, et al. Effects of interference fit screw length on tibial fixation for anterior cruciate ligament reconstruction. Am J Sports Med 2000;28:846–849. 9. Pomeroy G, Baltz M, Pierz K, et al. The effects of bone plug length and screw diameter on the holding strength of bone-tendon-bone grafts. Arthroscopy 1998;14:148–152. 10. Kao JT, Tibone JE, Shaffer B. The pullout strength and use of tibial interference screws during endoscopic ACL reconstruction surgery. Am J Knee Surg 1995;8:42–47. 11. McGuire DA, Barber FA, Elrod BF, et al. Bioabsorbable interference screws for graft fixation in anterior cruciate ligament reconstruction. Arthroscopy 1999;15:463–473. 12. Kaeding C, Farr J, Kavanaugh T, et al. A prospective randomized comparison of bioabsorbable and titanium anterior cruciate ligament interference screws. Arthroscopy 2005;21:147–151. 13. Ambrose CG, Clanton TO. Bioabsorbable implants: review of clinical experience in orthopedic surgery. Ann Biomed Eng 2004;32:171–177. 14. Bostman OM, Pihlajamaki HK. Adverse tissue reactions to bioabsorbable fixation devices. Clin Orthop Relat Res 2000;371:216–227. 15. Morgan CD, Gehrmann RM, Jayo MJ, et al. Histologic findings with a bioabsorbable anterior cruciate ligament interference screw explant after 2.5 years in vivo. Arthroscopy 2002;18:E47. 16. Radford MJ, Noakes J, Read J, et al. The natural history of a bioabsorbable interference screw used for anterior cruciate ligament reconstruction with a 4-strand hamstring technique. Arthroscopy 2005;21:707–710. 17. Seil R, Rupp S, Krauss PW, et al. Comparison of initial fixation strength between biodegradable and metallic interference screws and a press-fit fixation technique in a porcine model. Am J Sports Med 1998;26:815–819.

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18. Kousa P, Jarvinen TL, Kannus P, et al. Initial fixation strength of bioabsorbable and titanium interference screws in anterior cruciate ligament reconstruction. Biomechanical evaluation by single cycle and cyclic loading. Am J Sports Med 2001;29:420–425. 19. Walton M. Absorbable and metal interference screws: comparison of graft security during healing. Arthroscopy 1999;15:818–826. 20. Fineberg MS, Zarin B, Sherman OH. Practical considerations in anterior cruciate ligament replacement surgery. Arthroscopy 2000;16:715–724. 21. Barrett GR, Treacy SH. The effect of intraoperative isometric measurement on the outcome of anterior cruciate ligament reconstruction: a clinical analysis. Arthroscopy 2000;12:645–651. 22. Lintner DM, Dewitt SE, Moseley JB. Radiographic evaluation of native anterior cruciate ligament attachments and graft placement for reconstruction. A cadaveric study. Am J Sports Med 1996;24:72–78. 23. Rupp S, Seil R, Krauss PW, et al. Cortical versus cancellous interference fixation for bone-patellar tendon-bone grafts. Arthroscopy 1998;14:484–488. 24. Brand JC Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 25. Yoshiya S, Nagano M, Kurosaka M, et al. Graft healing in the bone tunnel in anterior cruciate ligament reconstruction. Clin Orthop Relat Res 2000;376:278–286. 26. Lemos MJ, Albert J, Simon T, et al. Radiographic analysis of femoral interference screw placement during ACL reconstruction: endoscopic versus open technique. Arthroscopy 1993;9:154–158. 27. Cerrullo G, Puddu G. Arthroscopic placement of the interference screw for anterior cruciate ligament reconstruction. Arthroscopy 1993;9:712–713. 28. Brodie JT, Torpey BM, Donald GD III, et al. Femoral interference screw placement through the tibial tunnel: a radiographic evaluation of interference screw divergence angles after endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1996;12:435–440. 29. Schroeder FJ. Reduction of femoral interference screw divergence during endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1999;15:41–48. 30. Pierz K, Baltz M, Fulkerson J. The effect of Kurosaka screw divergence on the holding strength of bone-tendon-bone grafts. Am J Sports Med 1995;23:332–335. 31. Lemos MJ, Jackson DW, Lee TQ, et al. Assessment of initial fixation of endoscopic interference screws with divergent and parallel placement. Arthroscopy 1995;11:37–41. 32. Jomha N, Raso V, Leung P. Effect of varying angles on the pullout strength of interference screw fixation. Arthroscopy 1993;9:580–583. 33. Ha KI, Kim SH, Ahn JH. The HAKI technique of femoral interference screw insertion. Arthroscopy 1999;15:110–114. 34. Rodin D, Levy IM. The use of intraoperative fluoroscopy to reduce femoral interference screw divergence during endoscopic anterior cruciate ligament reconstruction. Arthroscopy 2003;19:314–317. 35. Matthews LS, Lawrence SJ, Yahiro MA, et al. Fixation strengths of patellar tendon-bone grafts. Arthroscopy 1993;9:76–81. 36. Shaffer B, Gow W, Tibone JE. Graft-tunnel mismatch in endoscopic anterior cruciate ligament reconstruction: a new technique of intraarticular measurement and modified graft harvesting. Arthroscopy 1993;9:633–646. 37. Olszewski A, Miller M, Ritchie J. Ideal tibial tunnel length for endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1998;14:9–14. 38. Denti M, Bigoni M, Randelli P, et al. Graft-tunnel mismatch in endoscopic anterior cruciate ligament reconstruction. Intraoperative and cadaver measurement of the intra-articular graft length and the length of the patellar tendon. Knee Surg Sports Traumatol Arthrosc 1998;6:165–168. 39. Taylor DE, Dervin GF, Keene GCR. Femoral bone plug recession in endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1996;12:513–515. 40. Auge WK II, Yifan K. A technique for resolution of graft-tunnel length mismatch in central third bone-patellar tendon-bone anterior cruciate ligament reconstruction. Arthroscopy 1999;15:877–881.

Interference Screw Fixation in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction 41. Barber FA, Spruill B, Sheluga M. The effect of outlet fixation on tunnel widening. Arthroscopy 2003;19:485–492. 42. Stapleton TR, Waldrop JI, Ruder CR, et al. Graft fixation strength with arthroscopic anterior cruciate ligament reconstruction. Two-incision rear entry technique compared with one-incision technique. Am J Sports Med 1998;26:442–445. 43. Pena F, Grontvedt T, Brown GA, et al. Comparison of failure strength between metallic and absorbable interference screws. Influence of insertion torque, tunnel-bone block gap, bone mineral density, and interference. Am J Sports Med 1996;24:329–334.

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44. Barrett GR, Papendick L, Miller C. Endobutton button endoscopic fixation technique in anterior cruciate ligament reconstruction. Arthroscopy 1995;11:340–343. 45. Honl M, Carrero V, Hille E, et al. Bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction: an in vitro comparison of mechanical behavior under failure tensile loading and cyclic submaximal tensile loading. Am J Sports Med 2002;30:549–557. 46. Berg EE. Autograft bone-patella tendon-bone plug comminution with loss of ligament fixation and stability. Arthroscopy 1996;12:232–235.

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49 CHAPTER

K. Donald Shelbourne

Anterior Cruciate Ligament Reconstruction Using a Mini-Arthrotomy Technique with Either an Ipsilateral or a Contralateral Autogenous Patellar Tendon Graft INTRODUCTION There are many techniques for anterior cruciate ligament (ACL) reconstruction that involve using different surgical instruments, graft choices, fixation devices, and postoperative care. Each surgeon needs to become an expert at one technique, track the patients’ results, and then make refinements in the surgery and rehabilitation to optimize outcomes. It is important to note that ACL surgery is not just a surgery but also involves specific preoperative and postoperative rehabilitation programs to obtain a good result. Specific rehabilitation guidelines will be covered in other chapters in this book. The purpose of this chapter is to describe a technique for ACL reconstruction using autogenous patellar tendon graft from either the ipsilateral or contralateral knee. In the past 24 years, I have performed more than 5000 ACL reconstructions, and I have always used an autogenous patellar tendon graft for all the surgeries. I prefer to use the patellar tendon graft because it allows for quick and predictable bone-to-bone healing, is viable throughout the entire postoperative course,1 and can respond to stress during rehabilitation. Although any biological graft that is properly placed in the knee can achieve the same stability after surgery, the patellar tendon graft may allow for the fastest postoperative rehabilitation program because bone–bone healing is quicker than tendon–bone healing. Regardless of graft

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choice, proper rehabilitation must be done to give the best result.

PREOPERATIVE PLANNING Radiographs Radiographs are obtained preoperatively to assist with surgery planning. Plain radiographs, including standing posteroanterior 45 degrees flexed weight bearing,2 lateral, and Merchant3 views are obtained. The radiographs allow us to measure the width of the intercondylar notch, length of the patellar tendon, tibial slope angle, and width of the patella, which is usually twice the width of the patellar tendon. These measurements are helpful for planning the angle and length of the femoral tunnel and help determine the amount of notchplasty that may be needed to accommodate for the width of the new ACL graft. A magnetic resonance imaging (MRI) scan is not necessary for our preoperative evaluation but is reviewed if it has already been obtained elsewhere.

Rehabilitation There is never a reason to do an isolated ACL reconstruction as an emergency surgery. Previous studies have shown that acute ACL reconstruction has a higher rate of postoperative

Anterior Cruciate Ligament Reconstruction Using a Mini-Arthrotomy Technique with Either an Ipsilateral or a Contralateral Autogenous Patellar Tendon Graft arthrofibrosis than delayed ACL reconstruction when the patient has the opportunity to undergo rehabilitation to allow the knee to return to a quiescent state.4,5 All patients are evaluated by a physical therapist at the time of my initial evaluation. The physical therapist measures knee range of motion and strength before surgery and determines when the patient is ready to undergo surgery. The patient must have full knee range of motion equal to the contralateral normal knee, good leg control, and no knee swelling before he or she can undergo surgery. Furthermore, the patient must be mentally prepared for surgery. The surgery and rehabilitation program are fully explained to the patient and his or her caregiver so that they fully understand what is expected of them after surgery. The surgery date is planned for a time when the patient has at least 1 week off school or work and when a family member or friend can be at home with him or her during the first week postoperatively.

TECHNIQUE Preparation The patient lies supine on the operating table and is given a general endotracheal anesthesia. A knee evaluation for stability, range of motion, and effusion is performed after the patient is under anesthesia. The patient’s knees are positioned over the break in the table for flexion later. A tourniquet is applied to the thigh. A 30-mg bolus of ketorolac is administered for preemptive pain management. Then 90 mg of ketorolac is mixed with 1000 mL of saline and an intravenous drip is started to run at 40 m/hr until completion of the dose. Intravenous antibiotics are infused. The knee is preinjected with 0.25% Marcaine (bupivacaine hydrochloride, Winthrop, New York, NY) with epinephrine. The operative site is prepped with alcohol, and then the entire leg is painted with povidone-iodine (Betadine). An impervious stockinette is applied.

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Ioban (3M Healthcare, St. Paul, MN) is placed on the knee over the openings cut in the stockinette. A bump is placed under the distal thigh to hold the leg in 25 degrees of flexion.

Exposure The tourniquet is left inflated to 300 mHg/psi (350 mHg/ psi for larger thighs). The Ioban drape is taken off the skin just over the site where the skin incision is to be made. A 6-cm incision is made down to the deep fascia along the medial side of the patellar tendon, starting 1 cm above the inferior pole of the patella and extending 4 cm distal to the joint line (Fig. 49-1). The subcutaneous tissue is separated from the deep fascia medially where the tibial tunnel is to be drilled 4 cm distal to the joint and 1 cm medial to the tibia tubercle. The subcutaneous tissue is separated from the deep fascia with Metzenbaum scissors and finger dissection approximately 1 to 2 cm medial to the patellar tendon.

Tibial Exposure The deep fascia and periosteum of the proximal tibia are incised with electrocautery starting from the joint line and extending distally along the medial edge of the patellar tendon for 4 cm, then cutting at a right angle for another 2 cm to outline a flap to the level just proximal to the pes

Preparation When Using Graft from Contralateral Knee A tourniquet is applied but is not inflated at this time. The contralateral leg is prepped with alcohol, and the entire leg is painted with povidone-iodine (Betadine). An impervious stockinette is applied.

Arthroscopic Evaluation An arthroscopy is performed to examine the knee joint for articular cartilage damage and meniscal tears. Meniscal tears are treated with either repair or removal or are left in situ as appropriate. After the arthroscopy, the leg is redraped and

FIG. 49-1 A 6-cm incision is made along the medial side of the patellar tendon starting 1 cm above the inferior pole of the patella and extending 4 cm distal to the joint line.

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Anterior Cruciate Ligament Reconstruction anserinus. The periosteum/fascial flap is lifted with a periosteal elevator to expose bare bone where the tibial tunnel will be created, made, and drilled (Fig. 49-2). Exposure at this level will ensure the tibial tunnel will be at least 40 mm long for the 25-mm bone plugs. The flap is kept as thick and continuous as possible to allow for closure of the soft tissue over the polyethylene button used for fixation, which has reduced the need for postoperative hardware removal.

Medial Arthrotomy A finger is used to put tension on the medial capsule just medial to the patella as electrocautery is used to incise the capsule into the joint at 5 to 10 mm medial to the patella, starting at the level of the lower third of the patella, extending distally to the tibia, and staying medial to the fat pad. Tension is applied to the synovial layer with forceps on both sides of the incision. After making an opening in the synovium, a Z retractor is inserted to retract the patellar tendon laterally. A small fork retractor is inserted inside the synovium to retract the soft tissue medially. The incision is extended distally along the medial edge of the patellar tendon toward the tibial periosteal incision, thus connecting the two incisions. The incision in the fat pad should stay just medial to the ligamentum mucosum for better exposure of the joint. At the tibial plateau, the soft tissue is incised up to the intermeniscal ligament. Proximally, an incision is made in the retinaculum up to the distal fibers of the vastus

FIG. 49-2 A periosteum/fascial flap is lifted to expose the bone at the site where the tibial tunnel is drilled.

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medialis obliquus, cutting from inside the joint toward the surface to avoid inadvertent injury to the articular surface. It is not necessary to dislocate the patella for this exposure.

Femoral Exposure The patellar tendon length is determined preoperatively from a 60-degree-flexion lateral plain radiograph. The length of the tendon varies from 34 to 74 mm (mean 49 mm for men and 46 mm for women). Longer patellar tendons need longer femoral tunnels. The intraarticular ACL length varies from 22 to 30 mm, so the extra length of the graft is placed in the femur. The bone plug in the tibia is placed just distal to the medial tibial spine because the only hard cancellous bone in the tibia is at the proximal joint line. The femoral tunnel exit site is adjusted based on the length of the graft. For longer patellar tendons, the incision will be made more proximally; for shorter patellar tendons, the incision is made more distally. In our experience, an oblique incision has resulted in fewer wound-healing problems than a longitudinal incision in line with the iliotibial band. The table is elevated so that the femur is close to eye level. The foot of the bed is lowered so that the knee is flexed to 90 degrees. The bump under the thigh may need to be adjusted to allow for 90 degrees of flexion. The goal is to expose the flat surface of the lateral femoral cortex above the metaphyseal flare. The 3-cm lateral oblique incision is made about 4 to 5 cm above the superior pole of the patella along Langer’s lines (Fig. 49-3). Sharp dissection is made down to the iliotibial band. Metzenbaum scissors are used to split the iliotibial band along its fibers at a level one-third of its width from the anterior edge. With the knee extended to relax the quadriceps muscle, finger dissection is used to sweep the distal fibers of the vastus lateralis anteriorly from the femur. A Slocum retractor is inserted

FIG. 49-3 A 3-cm lateral incision is made at a 45-degree angle. The distal end is posterior and ends 5 cm above the level of the superior pole of the patella.

Anterior Cruciate Ligament Reconstruction Using a Mini-Arthrotomy Technique with Either an Ipsilateral or a Contralateral Autogenous Patellar Tendon Graft beneath the vastus lateralis, lifting it anteriorly to expose the femur, and a Cushing retractor is used to retract the posterior portion of the iliotibial band. A two-prong retractor pulls the skin distally so that the electrocautery can be used to incise the iliotibial band distally. Frequently the lateral superior geniculate artery, veins, or both are in the distal aspect of the wound running along the femoral surface. These vessels should be cauterized as soon as identified to avoid a postoperative hematoma. Electrocautery is then used to incise the periosteum, making a distally based T. An elevator is used to elevate the periosteal flaps to expose bone.

Notchplasty The lateral aspect of the notch is cleared of any ACL remnant and scar tissue, if present. The curette and sponge are used to push the capsule away from the back of the notch so that its posterior wall over-the-top position can easily be seen and palpated. The width of the notch and the space between the lateral femoral condyle and the posterior cruciate ligament (PCL) are measured with calipers (Fig. 49-4). The space between the lateral femoral condyle and the PCL is the space available for the ACL graft; it averages 8 mm in width for men and 6 mm in width for women. The notchplasty is then performed with a large curette to create at least an 11-mm space between the border of the lateral femoral condyle and the PCL so that the new 10-mm patellar tendon graft will fit in the notch in full extension without impingement.

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predictably. Ideal graft placement will result in the graft lying flush with the roof of the notch with the knee in full extension. A postoperative full-extension lateral radiograph should show the tibial tunnel to be parallel and posterior to Blumensaat’s line. Too anterior of a position may result in graft impingement when the knee is fully extended and may cause difficulty with obtaining extension and possibly graft failure. The tibial periosteal/fascial flap is retracted medially with a Cushing retractor. A 3/32-inch guide pin is placed on the anteromedial tibia about 4 cm below the joint line. The guide pin is directed 5 mm medial to the tibial spine and at least 5 mm anterior to where the tibial plateau “drops off” in the sagittal plane. This point can be found by palpation and represents an ideal placement for the tibial tunnel. We view the visible portion of the medial tibial plateau as a clock. The 9-o’clock position serves as the middle of the visible tibial plateau for the right knee (3-o’clock position for a left knee). The center of the ideal tibial tunnel corresponds to the position just posterior to the 9- or 3-o’clock position (Fig. 49-5). The tip of the guide pin is 5 mm medial to the tibial spine and 6 to 7 mm anterior to the posterior sloping of the tibial plateau where the PCL crosses. After an acceptable position is achieved, the guide pin is over-reamed with a 9-mm, endcutting, cannulated reamer (Fig. 49-6). Reamings are saved for bone grafting of the graft harvest site later in the procedure. Curettes are used to position the medial and posterior wall of the tunnel in the desired place (Fig. 49-7).

Tunnel Placement

PCL

Tibial Tunnel The ACL attachment on the tibia has a wider footprint than the femoral insertion and is more difficult to place

Medial

Lateral

Area of posteriorization

FIG. 49-4 Calipers are used to measure the width of the intercondylar notch, and the space between the posterior cruciate ligament and the lateral femoral condyle.

5mm

FIG. 49-5 Tibial tunnel placement. A clock face is interposed on the portion of the medial tibial plateau that is visualized through the mini-arthrotomy. The area of posteriorization is created for refinement of the position so that the back of the tunnel is just at the front slope of the tibial spine. PCL, Posterior cruciate ligament.

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Anterior Cruciate Ligament Reconstruction 10-mm tunnel just adjacent to the PCL and just off the back wall. The guide pin is then drilled toward the cleared-off lateral femoral cortex in the lateral oblique incision. If the guide pin does not exit in the area of the cleared-off cortex, it must be redirected using the same starting point. Once the pin is in an acceptable position, it is over-reamed with a 10-mm end-cutting reamer to the lateral femoral cortex (Fig. 49-8). Bone reamings are once again saved for filling in the graft harvest site. The joint is irrigated thoroughly. The tunnel positions are checked using a suction tip. With the knee extended, the suction tip should pass colinearly through the tibial tunnel and femoral tunnel (Fig. 49-9). FIG. 49-6 After precise placement of the tibial tunnel is achieved with a guide pin, the guide pin is over-reamed with a cannulated reamer.

Femoral Tunnel Femoral tunnel placement is one of the more critical and technically difficult parts of the procedure. Graft placement that is too vertical (too anterior on radiograph) is probably the most common problem seen in nontraumatic failed ACL surgery. The mini-arthrotomy technique allows for anatomical placement of the femoral tunnel because it is drilled independently of the tibial tunnel. The tunnels can be placed where desired because of the ability to view the notch and the posterior wall. The extremity is placed in a figure-four position. The posterior wall must be well visualized just adjacent to the PCL. The guide pin is used to palpate the edge of the back wall and the lateral border of the PCL. From this point, the guide pin is moved forward 6 to 7 mm and laterally 3 to 4 mm. This allows for a

FIG. 49-7 A curette is used to position the medial and posterior wall of the tibial tunnel in the position shown in Fig. 49-5.

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FIG. 49-8 Femoral tunnel. A 10-mm tunnel is drilled just adjacent to the posterior cruciate ligament and just off the back wall of the femur.

FIG. 49-9 Straight-line placement of the graft is checked using a suction tip, which should pass colinearly through the tibial and femoral tunnels.

Anterior Cruciate Ligament Reconstruction Using a Mini-Arthrotomy Technique with Either an Ipsilateral or a Contralateral Autogenous Patellar Tendon Graft

Graft Harvest and Preparation Ipsilateral Graft We prefer to harvest the graft after placement of the tunnels. This allows for harvesting of a graft to fit the tunnels, rather than vice versa. The knee is bent to 90 degrees, and the foot of the table is lowered. An incision is made just medial to the patellar tendon, from the inferior pole of the patella to the level of the tibial tubercle. The length of the incision depends on the length of the patellar tendon, which has been determined by measuring preoperative radiographs. The subcutaneous tissue is undermined sharply, exposing the patellar tendon. The paratenon is split longitudinally, and adequate flaps are maintained for later closure. The width of the tendon is measured. A 10-mm-wide graft is harvested using a #10 scalpel (Fig. 49-10). The bony blocks are scored with the scalpel so that the bone blocks will measure approximately 10 mm wide and 25 mm long. An oscillating saw is used to harvest the bone blocks in a wedge-shaped fashion (Fig. 49-11). The saw blade should

49

be angled in 45 degrees toward the midline. The bone blocks are removed with a ¼-inch osteotome and contoured so that they will fit in their respective tunnels. Excess bone and soft tissue are removed with a rongeur. Three drill holes are drilled in each bone plug, and #2 Ethibond sutures are passed through the holes (Fig. 49-12). At this time, the graft is taken to the back table and excess fat pad is removed so that there will be no snagging when it passes through the tunnels. Measurements are taken of the patellar tendon length and the thickness and length of the graft. The patellar tendon graft is usually longer than the native ACL, but this extra length is easily accommodated by the femoral tunnel. The overall graft length should be 10 to 20 mm shorter than the overall tunnel length to allow for easy repositioning and tensioning while maintaining bone plugs inside the tunnels.

Contralateral Graft When a patellar tendon graft is used from the contralateral knee, the tourniquet on that leg is inflated immediately before graft harvest. The graft harvest is identical to that used for an ipsilateral graft, as explained earlier. The harvest site is injected with bupivacaine (Marcaine), the knee is wrapped with an elastic bandage, and the tourniquet is deflated.

Passage of the Graft, Fixation, and Tensioning

FIG. 49-10 A 10-mm-wide graft is harvested using a #10 scalpel.

A suture passer is passed into the tibial tunnel so that it exits the notch. The individual Ethibond sutures are passed through and brought out the tibial tunnel. The bone plug is guided into the tibial tunnel with the cancellous side anterior while keeping tension on the distal sutures. This places the graft so that the tendinous portion faces posteriorly, which helps to avoid impingement. Three suture ends are

FIG. 49-11 An oscillating saw is used to harvest wedge-shaped bone blocks.

FIG. 49-12 Three drill holes are placed in each bone plug, and #2 Ethibond sutures are passed through the holes.

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Anterior Cruciate Ligament Reconstruction each passed through a hole of a ligament fixation button (Fig. 49-13). These are provisionally tied with two throws. The sutures in the femoral bone plug are looped into the suture passer and passed from the notch, exiting through the lateral incision. The end of the suture passer is guided through the femoral tunnel exit, the sutures are removed from the passer, and the device is withdrawn from the knee. The sutures are passed through a ligament fixation button and tied down tightly over the lateral femoral cortex. The sutures on the tibial side are pulled firmly to seat the femoral button. The sutures over the tibial button are loosened and the patellar plug is advanced in the tibial tunnel, removing any slack in the graft. The tibial sutures are then retied. The knee is moved through a full range of motion from full hyperextension to full flexion (Fig. 49-14, A and B). If the graft was too tight before taking the knee through its full range of motion, the slip knots will accommodate by loosening just enough to allow for full motion. The tightness of the button on the tibia is checked again at 30 degrees of flexion. If it is too loose, the tibial sutures are retied, the knee is placed through full range of motion again, and the button is rechecked for proper tightness. If the sutures remain tight, three more throws are tied. This allows for fine-tuning of graft tension to avoid capturing the knee. The graft is then examined through the miniarthrotomy to ensure that notch impingement does not occur.

FIG. 49-13 Button fixation is used on both the tibial and femoral sides.

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Closure Ipsilateral Graft One-quarter (0.25) Marcaine with epinephrine is injected into the deep and subcutaneous tissues for analgesia and to decrease bleeding. Hemostasis is obtained by packing the wound with sponges and a compressive wrap. The tourniquet is then released. After 1 to 2 minutes, the dressing is removed, the wound is irrigated, and bleeders are cauterized.

FIG. 49-14 After button fixation is completed, the knee is moved through a full range of motion to include full hyperextension (A) and flexion so that the patient’s heel touches the buttocks (B).

Anterior Cruciate Ligament Reconstruction Using a Mini-Arthrotomy Technique with Either an Ipsilateral or a Contralateral Autogenous Patellar Tendon Graft A medium ConstaVac (Stryker, Kalamazoo, MI) drain is inserted into the lateral femoral wound. The graft donor site tendon defect is closed tightly with running #0 Vicryl (Ethicon, Somerville, NJ) suture through the paratenon, taken with a 2-mm piece of tendon on each side. We are able to close the defect tightly because we flex the knee fully after closure and again the evening after surgery. If the surgeon does not flex the knee fully on the day of surgery, he or she should close the defect loosely. Bone shavings obtained from drilling the femoral and tibial holes are packed into the patellar defect first. The tendon soft tissue over the patella defect is sutured over the bone graft material to contain it. Restoring the normal patella contour with the bone graft has been important in preventing the nuisance discomfort of leaving this defect. The tibial plug defect is filled with any remaining bone graft, and the tendon insertion is sewed over it as a continuation of the running stitch of the patellar tendon closure. The mini-arthrotomy capsule is closed with interrupted figure-eight stitches of #1 Vicryl. The knee is then taken through a full range of motion, and the button tightness is checked again before the fascial periosteum flap is closed over the button. A medium ConstaVac drain is inserted between the capsule and subcutaneous tissue. No intraarticular drain is used because the Cryo Cuff (Aircast, Summit, NJ) prevents a hemarthrosis and forces this blood subcutaneously where the drain will work. The iliotibial band is closed with #2–0 Vicryl. The subcutaneous tissue layer is closed with #3–0 Vicryl, and a running subcuticular #3–0 Proline suture is used for the skin. The incisions are covered with steri-strips. Plastizote squares (5  3  ¼ inches) are applied over the steri-strips for local skin compression, making for a more cosmetic scar and prevention of a subcutaneous hematoma. An antiembolism stocking (Kendall, Mansfield, MA) and a cold/compression device (Fig. 49-15) (Cryo Cuff) are applied to assist in preventing swelling.

FIG. 49-15 A cold/compression device is placed on the knee in the operating room to prevent the formation of a hemarthrosis.

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Contralateral Graft When a contralateral graft is used, the graft donor site is closed as previously explained.

Postoperative Care Upon admission to the hospital ward, the leg is kept elevated and moving in a continuous passive motion machine. Extension and flexion exercises begin as outlined in previous publications.6 The intravenous drip of ketorolac continues for approximately 23 hours until the dose is completed. The ketorolac, supplemented with 1 gm of acetaminophen every 6 hours, has provided excellent pain management for patients after the ACL reconstructive procedure.7 The overnight stay allows for patient and family education for the first week at home and ensures that the immediate postoperative goals are met, which prevents complications from developing.

COMMENTS The mini-arthrotomy technique using a patellar tendon autograft and suture-button fixation allows for reproducible excellent results and remains our method of choice for ACL reconstructions. Regardless of surgical technique, graft choice, or fixation device, the knee must be able to be moved through full range of motion after fixation to ensure that the graft placement has not captured the joint. The range of motion illustrated in Fig. 49-14 shows that the full knee extension includes hyperextension and the full flexion involves bringing the patient’s heel to the buttocks. If full range of motion cannot be obtained in the operating room after graft fixation, then it cannot be expected that the patient will be able to achieve full range of motion after surgery. Full normal range of motion is required for the patient to achieve the optimal result after surgery. The mini-arthrotomy technique might be considered “old-fashioned” by many, but it has several advantages over the arthroscopic technique. The angle of drilling the femoral tunnel from inside to outside is enhanced when starting medial to the patellar tendon. The medial approach allows the guide pin to exit at a desirable lateral position. By not relying on the patellar tendon defect for exposure, the graft harvest can be delayed until the tunnels are prepared and thus the bone plug size can be appropriately modified. Drilling the femoral and tibial hole through an arthrotomy allows for a complete overall view of the ACL placement. It also allows for the retrieval of bone shavings for bone grafting of the donor sites. These bone shavings would be washed away when using arthroscopic techniques. 371

Anterior Cruciate Ligament Reconstruction The only ACL injury in which acute or semi-acute surgery is indicated is when the patient has a dislocated knee involving the lateral side. The mini-arthrotomy technique allows for acute surgery, whereas acute surgery cannot be done arthroscopically because arthroscopic fluid cannot be contained in the knee joint due to the lateral capsule injury. The use of button fixation has advantages as well. The buttons allow for adjustment of graft tension (multiple times, if necessary) so that stability is achieved while maintaining full range of motion. Also, complete circumferential healing of the plug to the host is allowed because no foreign material is lodged next to the bone plug. Revision surgery is simpler with button fixation because no hardware needs to be removed in order to make new tunnels.

Special Considerations with Contralateral Graft The use of a patellar tendon graft from the contralateral knee can allow patients to have a quicker return of range of motion in the ACL reconstructed knee and a quicker return to sports. However, the use of this graft source in itself does not guarantee patients a quick return to activities.

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It is important to note that proper and specific rehabilitation must be done for the graft-donor site to be able to achieve these goals. Specific rehabilitation guidelines are described in the rehabilitation chapter in this book.

References 1. Rougraff B, Shelbourne KD, Gerth PK, et al. Arthroscopic and histologic analysis of human patellar tendon autografts used for anterior cruciate ligament reconstruction. Am J Sports Med 1993;21:277–284. 2. Rosenberg TD, Paulos LE, Parker RD, et al. The forty-five-degree posteroanterior flexion weight-bearing radiograph of the knee. J Bone Joint Surg 1988;70A:1479–1483. 3. Merchant AC. Patellofemoral malalignment and instabilities. In Ewing JW (ed). Articular cartilage and knee joint function: basic science and arthroscopy. New York, 1990, Raven Press, pp 79–91. 4. Mohtadi NG, Bogaert SW, Fowler PJ. Limitation of motion following anterior cruciate ligament reconstruction. A case control study. Am J Sports Med 1991;19:620–625. 5. Shelbourne KD, Wilckens JH, Mollabashy A, et al. Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation. Am J Sports Med 1991;19:332–336. 6. Shelbourne KD, Klootwyk TE, DeCarlo MS. Rehabilitation program for anterior cruciate ligament reconstruction. Sports Med Arthrosc Rev 1997;5:77–82. 7. Shelbourne KD, Liotta FJ, Goodloe SL. Preemptive pain management program for anterior cruciate ligament reconstruction. Am J Knee Surg 1998;11:116–119.

Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction Using the Endobutton Continuous Loop Bone–Tendon–Bone Fixation System The Endobutton Continuous Loop (CL) (Smith & Nephew, Andover, MA) for bone–tendon– bone (BTB) grafts is a femoral fixation system for grafts that have a bone block for the femoral attachment, such as BTB autografts, BTB allografts, and Achilles tendon allografts. The Endobutton-CL BTB offers several advantages compared with other forms of fixation, including interference fixation. The technique is easy, reproducible, and dependable while at the same time offering possibly the strongest fixation for BTB grafts available. Several advantages include a short learning curve; fewer steps than interference fixation; no needed calculations, minimizing error; and complete apposition of the bone block in the femoral tunnel. Complete apposition of the bone block allows for circumferential healing of the bone block within the tunnel. It also means that revision cases do not run the risk of voids in the bone left from interference screws. More advantages include the fact that perforation of the posterior femoral cortex will not compromise fixation. Another advantage that I enjoy the greatest is that the BTB graft can be “automatically” countersunk in the femoral tunnel, allowing the tibial bone block to easily end flush with the tibial cortex. This eliminates the problem of the graft being “too long” and thus eliminates the tibial bone block protruding out the tibial tunnel. In other words, there is no longer a risk of the graft being too long whether using autografts or allografts and therefore no need for tricks to accommodate this, such as steeper angles on the tibial tunnel. Having the tibial bone block end flush with the tibial cortex also makes tibial fixation much easier. Continued advantages

are that this technique avoids complications seen from interference fixation such as screw divergence, posterior blowout, laceration of the graft, screw breakage, and retained hardware or voids encountered during revision surgery. Finally, as already alluded to, revision anterior cruciate ligament (ACL) surgery becomes much easier for all these reasons. Revision ACL surgeries are usually as simple as primary ACL reconstructions. The Endobutton-CL is a small metal button that is attached to a continuous loop of nylon. The continuous loop means that there is no knot, thus eliminating the risk of knots loosening or tightening under a load; both situations lead to a lengthening of a construct and thus failure. The continuous loop (CL) comes threaded through the metal Endobutton. The loop is then threaded through the graft and back on itself. Thus it is a closed loop system that eliminates a weak link. This minimizes creep or failure of the construct. It is well accepted that the weak link in ACL reconstruction surgery is fixation of the graft during the immediate postoperative period. The Endobutton-CL offers one of the strongest forms of fixation available, with pullout strengths averaging 1345N compared with interference screws that average approximately 700N.*

50 CHAPTER

Stuart E. Fromm

TECHNIQUE OVERVIEW To emphasize the simplicity of the technique, an overview is presented first, followed by a more detailed description with pearls. *Data on file at Smith & Nephew, Andover, MA.

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Anterior Cruciate Ligament Reconstruction

6 Measure the length from the lateral femoral cortex to the opening of the tibial tunnel, and set the “stop” on the depth gauge. 7 The length of the needed CL is measured directly off the depth gauge when the graft is set beside it. 8 Attach the CL to the graft. 9 Pass the graft, flip the Endobutton, and tension the graft. 10 Fix the tibial bone plug.

TECHNIQUE IN DETAIL

50

40

30

20

The technique has a small learning curve with no needed calculations, which minimizes error. Standard setup and knee arthroscopy are performed. The bone–patellar tendon–bone graft is prepared in the usual manner, regardless of whether an autograft or allograft is used. Personally I leave the bone plugs no longer than 20 mm. Grafts are usually 9 or 10 mm in diameter. Tibial and femoral tunnels are likewise drilled in the usual manner. In fact, the femoral tunnel can be drilled right off the posterior femoral cortex without fear of breaking through of the posterior wall, as it will not compromise fixation. I use a 6-mm offset guide for a 10-mm tunnel, which places the femoral tunnel immediately against the posterior femoral cortex. Before reaming the femoral tunnel, check

FIG. 50-1 Grafts usually measure approximately 80 to 90 mm in total length.

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100

5 Leave the guide pin in place, and drill over it with the 4.5-mm Endobutton drill bit through the lateral femoral cortex.

90

4 Ream the femoral tunnel to a depth of the length of the BTB graft as measured directly off the reamer at the opening of the tibial tunnel. Then ream an extra 10 mm to allow room for the Endobutton to flip when passed.

80

3 Ream the tibial tunnel in the usual manner.

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2 Prepare the BTB graft in the usual manner.

the length of the graft. Grafts usually measure approximately 80 to 90 mm in total length (Fig. 50-1). Ream the femoral tunnel to a depth of the length of the graft as measured directly off the reamer at the tibial cortex. For example, if the graft length is 90 mm, ream to a depth of 90 mm as measured on the reamer at the opening of the tibial tunnel (Fig. 50-2). By doing this, the reamer is mimicking the graft itself and therefore mimicking where the graft will be placed, thus allowing the tibial bone plug to end flush with the tibial cortex. It is no longer necessary to measure the femoral tunnel; however, as a check, the femoral tunnel is usually reamed to a depth of approximately 30 mm. Then ream an extra 10 mm deeper to allow room for the Endobutton to flip outside of the lateral femoral cortex. Try to not perforate the lateral femoral cortex with the reamer. On longer grafts, you can run the risk of running out of room for the femoral tunnel. One way to effectively add length to the femoral tunnel is to flex the knee less than 90 degrees. This lessens the angle of the femoral tunnel, placing it more in line with the femur, and therefore adds length to the femoral tunnel if needed for longer grafts (Fig. 50-3). However, if there is inadvertent perforation of the femoral tunnel, it can be dealt with using the Xtendobutton, which is discussed later in this chapter. Leave the guide pin in place, and drill over it with the 4.5-mm Endobutton drill bit (Fig. 50-4). Remove the guide pin. Smith & Nephew makes a depth gauge with a stop on it (Fig. 50-5). Measure from the lateral femoral cortex to the opening of the tibial tunnel. Set the stop at the opening of the tibial tunnel (Fig. 50-6). This will be the length of the entire construct from the Endobutton to the end of the tibial bone plug on your graft. You do not need to know the actual number or distance; simply hand the depth gauge with the stop in place to the associate who is preparing the graft. The associate will lay the graft next to the depth gauge with the tibial bone plug at the stop. Measure directly the length of the needed CL, which is usually 40 to 45 mm (Fig. 50-7; shown here with a quadriceps tendon graft with a bone block on only one end).

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1 Standard knee arthroscopy is performed.

Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction Using the Endobutton Continuous Loop Bone–Tendon–Bone Fixation System

50

90

10 0 FIG. 50-5 Measure from the lateral femoral cortex to the opening of the tibial tunnel. Set the stop at the opening of the tibial tunnel.

To

ta

l le

ng

th

FIG. 50-2 If the graft length is 90 mm, then ream to a depth of 90 mm as measured on the reamer at the opening of the tibial tunnel.

FIG. 50-3 One way to effectively add length to the femoral tunnel is to flex the knee less than 90 degrees. This lessens the angle of the femoral tunnel, placing it more in line with the femur, and therefore adds length to the femoral tunnel if needed for longer grafts. FIG. 50-6 This will be the length of the entire construct from the Endobutton to the end of the tibial bone plug on the graft.

FIG. 50-4 Leave the guide pin in place, and drill over it with the 4.5-mm Endobutton drill bit.

The distance is measured from the 0 on the depth gauge to the point of attachment of the CL to the graft, whether it is at the bone–tendon junction or a small drill hole in the bone plug itself. Attach the CL to the graft. The Endobutton-CL can be divided into three areas: a long loop, a short loop, and the Endobutton (Fig. 50-8). When passing the CL, it is much easier to pull it rather than push it. Trying to push the CL only causes it to fray. Therefore it is advisable to pull the CL through its path with a small nonbraided suture. Simply loop 375

Anterior Cruciate Ligament Reconstruction Total length

FIG. 50-7 Measure directly the length of the needed continuous loop, which is usually 40 to 45 mm, shown here with a quadriceps tendon graft with bone block on only one end.

this suture around the long loop of the CL. Pull the long loop of the CL via the suture through either the bone–tendon junction or through a small 2-mm drill hole in the bone block. When using a drill hole through the bone block, make sure that it passed through the cortical side of the block and is more

than half the distance toward the tendon to avoid the CL from pulling through soft bone. Instron studies while the BTB CL was under development showed no difference in pullout strength when passing the CL at the bone–tendon junction versus through a 2-mm hole in the bone block. Then pull

FIG. 50-8 The Endobutton-CL can be divided into three areas: a long loop, a short loop, and the Endobutton.

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Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction Using the Endobutton Continuous Loop Bone–Tendon–Bone Fixation System the long loop through the short loop, and slip it over the Endobutton (Fig. 50-9). Pull to tighten. Check the total length against the depth gauge to ensure accuracy. Pull the graft into place. Attach a #5 suture through one of the holes in the Endobutton and a #2 suture through the other, or place different-colored sutures through each hole so that you will be able to tell them apart when passed (Fig. 50-10). Thread all sutures through a passing pin (the two sutures for the Endobutton and the passing suture through the bone block). Pull the passing pin out the lateral thigh with the sutures (Fig. 50-11). Separate the sutures. Pull the graft into position with the #5 suture and the passing suture, letting the #2 suture trail (Fig. 50-12). The graft will have a definite stop when it is passed far enough to flip the button. In addition, you will know the graft is far enough when the tibial bone plug is within the tibial tunnel. Flip the Endobutton by rocking the Endobutton back and forth using the #5 and #2 sutures. Then hold the Endobutton perpendicular to the lateral femoral cortex and pull back on the graft, ensuring fixation (Fig. 50-13). The tibial bone plug should be flush with the tibial cortex. Tension the graft, and fix the tibial bone block accordingly.

FIG. 50-9 Pull the long loop through the short loop, and slip it over the Endobutton. Pull to tighten. Check the total length against the depth gauge to ensure accuracy.

50

REVISION ANTERIOR CRUCIATE LIGAMENT SURGERY No special tricks are needed when using this technique for revision ACL surgery. The technique is the same as that just described for a primary ACL reconstruction. When revising an ACL that was previously fixed with an interference screw, I usually leave the interference screw alone because it is usually not in the way. Interference screws are placed at the anterior edge of the femoral tunnel. Therefore I can usually drill the new femoral tunnel just off the posterior femoral cortex as described earlier without fear of breaking out the posterior cortex with this system—again, if the posterior cortex is perforated, this will not compromise fixation with the BTB CL. Doing this almost always puts the femoral tunnel posterior to a previously placed interference screw, and therefore these screws can simply be left alone.

Xtendobutton A newer addition to the family of Endobutton-CL for BTB is the Xtendobutton (Fig. 50-14), which is being finalized at

FIG. 50-10 Thread all sutures through a passing pin (the two sutures for the Endobutton and the passing suture through the bone block).

377

Anterior Cruciate Ligament Reconstruction

FIG. 50-11 Pull the passing pin out the lateral thigh with the sutures.

the time of publication of this chapter. This is simply a larger button that fits over the Endobutton, effectively making the Endobutton a larger button. The Endobutton slides through a 4.5-mm hole and will not slide back when flipped. The Xtendobutton slides through a larger hole (e.g., a 10-mm hole) and will not slide back when flipped. This can be used for inadvertent reaming through the lateral femoral cortex when drilling the femoral tunnel. Some surgeons in preliminary trials prefer to use this exclusively for femoral fixation, eliminating yet one more step. In other words, the surgeon could ream the tibial and femoral tunnels all the way through both cortices without measuring off the reamer and eliminating the need to drill with the 4.5-mm drill altogether.

TROUBLESHOOTING Although the Endobutton-CL BTB System is very user friendly, surgeons should be aware of a few tips or pearls. If a surgeon struggles to pull the femoral bone block into the femoral tunnel, a few things should be checked. First, as with any ACL reconstruction, an oversized bone block that gives a very tight fit in the bone tunnel can cause

378

a surgeon to struggle when pulling the graft into place. This is also true with the Endobutton-CL BTB system. Make sure that the bone block can slide through the appropriate sizer with the continuous loop in place. The continuous loop can add a very slight width to the width of the bone block. Another issue to be aware of is soft tissue around the opening of the femoral tunnel. If the opening of the femoral tunnel is not débrided adequately of soft tissue, then this tissue is drawn into the femoral tunnel with the bone block. The soft tissue will then impinge between the bone block and the wall of the tunnel, making it difficult to pull the bone block into place. Lastly, if the surgeon passes the continuous loop at the bone–tendon junction, then the bone block may “rock” as it enters the femoral tunnel. Therefore I use a passing suture such as a #2 PDS or Proline passed through the bone block at the midway point. When pulled with the other sutures, this guides the bone block straight up the femoral tunnel. A probe through a working portal may also be used to help guide the femoral bone block straight up the femoral tunnel. Another potential trouble spot may be if the surgeon routinely countersinks the femoral bone block so that the tibial bone block will lay flush with the tibial cortex, as I do. This usually requires a slightly longer femoral tunnel than the femoral bone block (approximately 10 mm longer). In other words, the longer the ACL graft, the longer the femoral tunnel needed so as to not have any of the tibial bone block or graft protruding out of the tibial tunnel. If the surgeon flexes the knee greater than 90 degrees, as is usually taught for interference fixation, then there is the potential to have a femoral tunnel too short to accommodate the graft. The surgeon then runs the risk of reaming through the lateral femoral cortex, which would not allow the use of the standard Endobutton-CL. There are a couple of ways around this. First, when using this system, I actually flex the knee less than 90 degrees. This lessens the angle of the guide pin and reamer, which in fact lengthens the femoral tunnel (see Fig. 50-3). Obviously one would not want to lessen the angle too far, as then the guide pin will exit the thigh near the tourniquet or leg holder if these were used. I have simply become accustomed to placing the guide pin so that it will exit the thigh just distal to the tourniquet. This requires the knee to be flexed slightly less than 90 degrees and usually leaves ample room for a femoral tunnel. If a surgeon inadvertently reams through the lateral femoral cortex, then he or she has a couple of options. First, the surgeon could fix the femoral bone plug with a standard interference screw. However, a more appealing option would be to simply slip an Xtendobutton over the Endobutton and fix the graft as though using a standard Endobutton, as described earlier.

Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction Using the Endobutton Continuous Loop Bone–Tendon–Bone Fixation System

A

50

B

FIG. 50-12 A, Pull the graft into position with the #5 suture and the passing suture, letting the #2 suture trail. B, The graft will have a definite stop when it is passed far enough to flip the button.

FIG. 50-13 Hold the Endobutton perpendicular to the lateral femoral cortex and pull back on the graft, ensuring fixation.

379

Anterior Cruciate Ligament Reconstruction

SUMMARY The Endobutton-CL BTB system offers what is designed to be “the best of both worlds” in femoral fixation of grafts that have a bone block on the femoral side of attachment, such as BTB autografts, BTB allografts, and Achilles tendon allografts. It offers one of the strongest methods of fixation while avoiding complications seen with interference screws and other types of femoral fixation. It also has made revision ACL surgery generally as simple as primary ACL surgery by eliminating complications left from interference fixation.

FIG. 50-14 A newer addition to the family of Endobutton-CL for the bone–tendon–bone graft is the Xtendobutton.

RESULTS The Endobutton-CL BTB has been available for implantation for nearly 2 years at the time of writing this chapter. To my knowledge, the results have been impressive. There have been no known failures or complications to date; however, it must be stressed that these results are subjective. Objective laboratory tests prior to release showed the EndobuttonCL to be possibly the strongest fixation available, both in terms of ultimate strength and creep.*

*Data on file at Smith & Nephew, Andover, MA.

380

PART I NEWER INTERFERENCE SCREW MATERIALS

Milagro (Beta-Tricalcium Phosphate, Polylactide Co-Glycolide Biocomposite) Interference Screw for Anterior Cruciate Ligament Reconstruction INTRODUCTION The initial interference fixation screws were made from metal and provided screw fixation for anterior cruciate ligament (ACL) reconstructions. Biodegradable interference fixation screws subsequently gained wide acceptance after their introduction in the early 1990s.1–5 The benefits of these biodegradable interference screws include reduction in the concerns previously associated with metal implants, including difficulties in postoperative imaging, reduced graft laceration during insertion, less chance of screw divergence during insertion, easier revision surgery (Fig. 51-1), and fewer problems with secondary arthritic procedures that might require the complete removal of a metal screw. In addition, the load to failure (LTF) strength of these screws is sufficient to allow for an aggressive rehabilitation program. Potential complications associated with biodegradable interference screws include the risk of screw breakage during insertion, decreased holding strength when compared with a metal alternative, and inflammatory reactions that could lead to lytic changes and cyst formation. Poly-L-lactic acid (PLLA) is the most common material used in biodegradable interference screws. These screws offer effective graft fixation with little evidence of adverse inflammatory reactions, and many years pass before any material degradation occurs.1–8 Interference screws made of lactic acid copolymers containing dextro and levo stereoisomers subsequently became available, as did copolymers of polylactic acid

and polyglycolide. The polymer degradation is more rapid with poly D, L-lactide (PDLLA) implants than pure PLLA in animal studies.9–11 The Milagro screw (DePuy Mitek, Norwood, MA) is composed of a composite of 30% osteoconductive beta tricalcium phosphate and 70% polylactic glycolic acid by weight and represents a new material for interference fixation screws. This review presents biomechanical data, an explanation of the material properties of the screw composition, and a discussion of the clinical technique.

51 CHAPTER

F. Alan Barber

BIOMECHANICAL AND BIOCHEMICAL DATA Implant degradation proceeds through five stages: hydration, depolymerization, loss of mass integrity, absorption, and elimination. How rapidly an implant is degraded is influenced by the polymer of which the implant is made, the degree of crystallization of that polymer, the initial mass of the polymer present (implant size), surface coverings, whether the polymer is self-reinforced, the processing technique used (machining or injection molding and sterilization technique), and the environment in which the implant is situated.12 In addition, the degradation mechanics of different polymers may differ considerably based on the hydrophilic or hydrophobic nature of the different polymers. Degradation starts at the amorphous phase of the implant and leads to fragmentation

381

Anterior Cruciate Ligament Reconstruction

FIG. 51-1 Biodegradable interference screws avoid some of the problems during revision surgery that are associated with the prior placement of metal screws.

of the material to smaller parts, which are then phagocytosed primarily by macrophages and polymorphonuclear leukocytes.13,14 The lactic acid component is broken down by hydrolysis. The resultant monomers enter the Krebs cycle and are further dissimilated into carbon dioxide and water.15 In addition to hydrolytic chain scission, glycolic acid monomers are degraded by the enzymatic activity of esterases and carboxypeptidases.16 All biodegradable materials cause some inflammatory response. The longer the degradation course, the less visible the response will be. Usually there is a mild, nonspecific tissue response with fibroblast activation and the invasion of macrophages, multinucleated foreign body giant cells, and polymorphonuclear leukocytes during the final stages of degradation. Because of the more rapid degradation associated with polyglycolic acid (PGA), there have been some foreign body reactions with varying degrees of severity ranging from mild osteolytic changes to intense granulomatous inflammatory soft tissue lesions that necessitate surgical intervention.17,18 Concerns about implants composed of pure PGA have led to the development of PGA copolymers that still have a more rapid rate of absorption compared with PLLA implants, but the literature supports their use with excellent clinical results. Lajtai et al19,20 reported good results with a lactide/ glycolide copolymer screw (85/15, D, L lactide/glycolide). Using magnetic resonance imaging (MRI scans), the screw was shown to remain intact for 4 months and then disappear by 6 months. Five years after implantation, the screw was completely reabsorbed and evidently replaced with new bone. Morgan et al21 evaluated a PLLA interference screw removed 382

en bloc from a patient 2.5 years after insertion. The histological examination and molecular weight measurements showed a 75% decrease in the molecular weight of the screw with implant fragmentation and new bone formation adjacent to the screw. This dramatically contrasted with the MRI evaluation of the patient, which showed the presence of a clear screw outline. MRI evaluations of PLLA screw show no evidence of any progressive absorption 4 years after implantation.22 However, a recent computed tomography (CT) evaluation of patients who underwent patellar tendon autograft ACL reconstruction using PLLA screws at least 7 years earlier demonstrated complete removal of the PLLA screws without any significant bone ingrowth into the screw site.23 The goal of using biodegradable polymers is to have an implant mechanically strong enough to perform its task and then degrade in a manner that is clinically insignificant. An additional advantage would be that once the degradation is complete, there would be no evidence of the implant ever having been in place. At this point, pure PLLA and copolymers of PLLA and PGA have demonstrated adequate strength as interference fixation screws to function effectively for ACL reconstructions. These PLLA and PLLA/ PGA copolymers have also demonstrated that they will eventually degrade and disappear, even though it may require many years for this to occur (longer for PLLA than for PLLA/PGA copolymer). The next step is to develop an implant that will result in bone filling the vacated screw site.

BASIC SCIENCE OF BETA-TRICALCIUM PHOSPHATE COPOLYMERS Bone replacement technology has been in development for many years. Calcium phosphate ceramic materials like betatricalcium phosphate (ß-TCP) have been studied as potential bone replacement materials for decades. The calcium phosphates are used as bone void fillers, autograft extenders, and coatings for various implants including joint replacements. They are also used in products in which reabsorption of the device and replacement with native bone are desired, including different orthopaedic and maxillofacial applications. Bone, as with other calcified tissue, is an intimate composite of organic (collagen and noncollagenous proteins) and inorganic or mineral phases. Bone has several important properties including osteoconductivity (the ability to serve as an interactive template or scaffold for forming new bone) and osteoinductivity (the ability to create new bone or osteogenesis). None of the current manufactured materials has the ability to form bone (osteoinductive), but the benefit of a material being osteoconductive and being able to act as a template into which the adjacent bone may migrate is clear. A biodegradable interference fixation screw with

Milagro (Beta-Tricalcium Phosphate, Polylactide Co-Glycolide Biocomposite) Interference Screw for Anterior Cruciate Ligament Reconstruction osteoconductive properties would enhance bone ingrowth into its location as it biodegrades. Composites are a blend or intimate mixture of two different materials. This blending usually imparts different properties to the composite than those that were possessed by either of the two separate materials individually. The compressive strength and stiffness of ß-TCP are very high and, when blended with PLLA, the resultant composite includes these properties as well. How well dispersed the two materials of a composite are with one another is another important property. Once blended, the more homogenous the composite, the better. Biocryl is a composite of ßTCP and PLLA. Biocryl is a very homogenous composite with a high degree of dispersion of both materials in the blend. This dispersion of the materials is achieved throughout the entire implant by a proprietary manufacturing process known as micro particle dispersion (MPD). The addition of polyglycolide to polylactide creates a copolymer that biodegrades much more rapidly than even a very amorphous form of pure PLLA. The Milagro screw is made of a material that combines the ß-TCP–PLLA (Biocryl) composite with PGA. This resultant compound polymer composite consists of 30% osteoconductive ß-TCP and 70% polylactide co-glycolide (PLGA). The presence of the ß-TCP encourages bone to fill in once the PLGA has reabsorbed.

51

FIG. 51-2 The Milagro screw can be used for femoral or tibial fixation for soft tissue or bone–tendon–bone autografts or allografts.

CLINICAL INFORMATION The Milagro screw can be used for femoral or tibial fixation for soft tissue or bone–tendon–bone (BTB) autografts or allografts (Fig. 51-2). It is available in various diameters from 7 to 12 mm and in 23-, 30-, and 35-mm lengths. The Milagro screw is made from a polymer composite, Biocryl Rapide. As previously mentioned, this material consists of 30% osteoconductive ß-TCP and 70% PLGA. The poly (lactide-co-glycolide) copolymer is composed of 15% PGA and 85% PLLA. This ratio of PGA to PLLA was chosen following animal studies to allow for a faster yet controlled absorption. This copolymer does not contain any of the D-isomer of lactic acid. This material was recently evaluated in the lateral femoral cortex of mature beagle dogs.24 Rods of either Biocryl Rapide or PLLA measuring 3  10 mm were inserted into defects in the cortex and evaluated at intervals up to 24 months. Histological evaluation at intervals looked for reabsorption of the material and cracks, cell infiltrations, erosions, and fragmentation of the implants. At 24 months postimplantation, clear differences existed between the PLLA rods and the Biocryl Rapide rods (Fig. 51-3). The reabsorption of the Biocryl Rapide was nearly complete at 24 months, and radiographic bridging was observed at the

FIG. 51-3 At 24 months postimplantation, the reabsorption of Biocryl Rapide rods was nearly complete and radiographic bridging was observed.

Biocryl Rapide sites but not at the PLLA sites. No evidence of inflammatory reaction or cellular necrosis was observed. By 24 months, the entire cross-section of the Biocryl Rapide test rods was absorbed and replaced by normal bone or bone plus fibrous tissue or adipose tissue. The circular orientation of the new bone was seen under polarized light. Clinically, the Milagro screw has been available since its introduction in October 2004. The Milagro screw can be used for both BTB autografts and allografts. In these cases the technique for insertion is essentially the same as for any other biodegradable BTB interference screw. The preferred length for BTB fixation is 23 mm, with the diameter of the screw 383

Anterior Cruciate Ligament Reconstruction reflecting the size of the tunnel drilled and the size of the bone plug. I most frequently use the 8-mm-diameter screw for both the femoral and tibial sides; however, on occasion a 9-mm screw will be required for the tibial fixation. Soft tissue grafts (hamstring allografts and autografts and the tendon side of a quadriceps tendon autograft or Achilles tendon allografts) require a longer interference interface between the soft tissue and the tunnel, especially in the tibial tunnel. For the hamstring or quadriceps soft tissue grafts, the 35-mm screw length is preferred. Once the tunnels are drilled and the graft is prepared, a groove is made in the superior area of the bone tunnel with a notcher for the subsequent placement of a guidewire. The graft is then pulled into the tunnels. Once the graft is in place, a guidewire is placed in this notched groove, which is now adjacent to the bone plug in the femoral tunnel. Using the guidewire, a tap is inserted and threads cut to the correct depth. If the bone is softer, it is only necessary to cut a few threads, which allows the Milagro screw to engage the bone and then cut its own way into the interference position. For denser bone, full tapping for the entire screw length is needed. The tap for the Milagro screw has distal threads that are blunt, whereas the more proximal threads are sharp. Care should be taken to avoid cutting the control sutures in the bone plug with these proximal tap threads during this tapping procedure. It is fairly easy to avoid cutting the sutures in the femoral plugs, but a greater awareness of the tibial plug orientation, its sutures, and where the tap is being inserted relative to both of these is required on the tibial side to avoid cutting the control sutures. Once tapping is complete, the Milagro interference screw is advanced over the guidewire to the appropriate depth. Resistance during insertion is expected and is felt to increase as the screw advances. An increasingly loud squeaking should be heard as the screw nears the fully seated position. Our experience is with the 8- and 9-mm-diameter sizes. We have not had the Milagro screw break when the tapping was successfully done. One case of screw breakage occurred when the tapping step was skipped. The thread depth as measured between the minor (or core) diameter and the outer diameter is better than other biodegradable screws in our experience, and the thread pitch (number of threads per length) provides sufficient spacing between the threads to grip and compress the adjacent cancellous bone. Postoperatively an aggressive rehabilitation program is followed. The speed and details of this program are dictated by the nature of the graft material selected and not by the presence of a biocomposite screw. The patellar tendon autograft reconstructions begin with maintaining full extension by prone hangs and a full-extension night brace. The knee flexion is encouraged by a constant passive motion machine for 6 to 8 hours during the day for as long as 2 weeks or 384

until comfortable flexion to 90 degrees is attained. Straight-ahead jogging without cutting is started at 6 weeks postsurgery and pivoting at 12 weeks postsurgery. Full contact is begun with a derotational knee brace between 12 and 16 weeks after surgery. Allograft and soft tissue graft reconstructions are returned to activity less aggressively. Because of the biocomposite in the Milagro screw, its position can be evaluated on postoperative radiographs. Postoperative radiographs are obtained on the first postoperative visit and serve as a baseline for subsequent evaluations. The ability to visualize the screw helps with assessing plug location.

PEARLS The tap associated with the Milagro screw has two types of threads. The distal threads are blunt, whereas the proximal threads are sharp. If the entire course of the screw is to be tapped, care should be taken that these cutting threads do not damage either the graft or the sutures attached to a bone plug. To reduce the chance of cutting the sutures, make certain that the guidewire is placed on the side of the plug between the two sets of sutures controlling the graft, and not through the sutures. Once the tibial screw is in place, tug on the graft sutures to demonstrate that there is good tension on the graft and no movement of the graft in the joint. If graft movement is observed, the graft should be retensioned and a second screw stacked beside the first to achieve secure fixation (Fig. 51-4).

FIG. 51-4 If secure fixation of the tibial graft is not achieved with a single screw, a second screw may be stacked beside the first to achieve secure fixation.

Milagro (Beta-Tricalcium Phosphate, Polylactide Co-Glycolide Biocomposite) Interference Screw for Anterior Cruciate Ligament Reconstruction

References 1. Barber FA, Elrod BF, McGuire DA, et al. Preliminary results of an absorbable interference screw. Arthroscopy 1995;11:537–548. 2. Marti C, Imhoff AB, Bahrs C, et al. Metallic versus bioabsorbable interference screw for fixation of bone-patellar tendon-bone autograft in arthroscopic anterior cruciate ligament reconstruction. A preliminary report. Knee Surg Sports Traumatol Arthrosc 1997;5:217–221. 3. Barber FA. Tripled semitendinosus-cancellous bone anterior cruciate ligament reconstruction with bioscrew fixation. Arthroscopy 1999;15:360–367. 4. Tuompo P, Partio EK, Jukkala-Partio K, et al. Comparison of polylactide screw and expansion bolt in bioabsorbable fixation with patellar tendon bone graft for anterior cruciate ligament rupture of the knee. A preliminary study. Knee Surg Sports Traumatol Arthrosc 1999;7:296–302. 5. McGuire DA, Barber FA, Elrod BF, et al. Bioabsorbable interference screws for graft fixation in anterior cruciate ligament reconstruction. Arthroscopy 1999;15:463–473. 6. Warden WH, Friedman R, Teresi LM, et al. Magnetic resonance imaging of bioabsorbable polylactic acid interference screws during the first 2 years after anterior cruciate ligament reconstruction. Arthroscopy 1999;15:474–480. 7. Barber FA, Elrod BF, McGuire DA, et al. Bioscrew fixation of patellar tendon autografts. Biomaterials 2000;21:2623–2629. 8. Kotani A, Ishii Y. Reconstruction of the anterior cruciate ligament using poly-L-lactide interference screws or titanium screws: a comparative study. Knee 2001;8:311–315. 9. Sedel L, Chabot F, Christel P, et al. Biodegradable implants in orthopedic surgery. Rev Chir Orthop Reparatrice Appar Mot 1978;64(Suppl 2):92–96. 10. Chen CC, Chueh JY, Tseng H, et al. Preparation and Characterization of biodegradable PLA polymeric blends. Biometrials 2003;24:1167–1173. 11. Barber FA. Poly-D, L-lactide interference screws for anterior cruciate ligament reconstruction. Arthroscopy 2005;21:804–808.

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12. Daniels AU, Chang MKO, Andriano KP. Mechanical properties of biodegradable polymers and composites proposed for internal fixation of bone. J Appl Biomater 1990;1:57–78. 13. Lam KH, Schakenrad JM, Esselbrugge H, et al. The effect of phagocytosis of poly (L-lactic acid) fragments on cellular morphology and viability. J Biomed Mater Res 1993;27:1569–1577. 14. Tabata Y, Ikada Y. Macrophage phagocytosis of biodegradable microspheres composed of L-lactic acid/glycolic acid homo- and copolymers. J Biomed Mater Res 1988;22:837–858. 15. Hollinger JO, Battistone GC. Biodegradable bone repair materials. Synthetic polymers and ceramics. Clin Orthop 1986;207:290–305. 16. Williams F, Mort E. Enzyme-accelerated hydrolysis of polyglycolic acid. J Bioengin 1977;1:231–238. 17. Böstman O, Pihlajamäki H, Partio E, et al. Clinical biocompatibility and degradation of polylevolactide screws in the ankle. Clin Orthop 1995;320:101–109. 18. Böstman O. Osteolytic changes accompanying degradation of absorbable fracture fixation implants. J Bone Joint Surg 1991;73B:679–682. 19. Lajtai G, Hummer K, Aitzetmuller G, et al. Serial magnetic resonance imaging evaluation of a bio-absorbable interference screw and the adjacent bone. Arthroscopy 1999;15:481–488. 20. Lajtai G, Schmiedhuber G, Unger F, et al. Bone tunnel remodeling at the site of bio-degradable interference screws used for anterior cruciate ligament reconstruction—five year follow up. Arthroscopy 2001;17:597–602. 21. Morgan CD, Gehrmann RM, Jayo MJ, et al. Histologic findings with a bio-absorbable anterior cruciate ligament interference screw explant after 2.5 years in vivo. Arthroscopy 2002;18:E47. 22. Radford MJ, Noakes J, Read J, et al. The natural history of a bioabsorbable interference screw used for anterior cruciate ligament reconstruction with a 4-strand hamstring technique. Arthroscopy 2005;21:707–710. 23. Barber FA, Dockery WD. Long term absorption of poly L-lactic acid interference screws. Arthroscopy 2006;22:820–826. 24. Poandl T, Trenka-Benthin S, Azri-Meehan S, et al. A new faster degrading biocomposite material: long-term in-vivo tissue reaction and absorption. AANA Annual Meeting e-poster (E-09), 2005, Vancouver.

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52 CHAPTER

Timo Järvelä Janne T. Nurmi Antti Paakkala Anna-Stina Moisala Auvo Kaikkonen Markku Järvinen

386

Improving Biodegradable Interference Screw Properties by Combining Polymers INTRODUCTION Interference screws are widely used for graft fixation in anterior cruciate ligament (ACL) reconstruction, and good clinical results have been reported by several investigators.1–5 In addition to conventional metal screws, biodegradable interference screws are commercially available and have been shown to provide at least as strong graft fixation as metal screws.6,7 In addition, the biodegradable screws do not interfere with imaging techniques and do not need to be removed in revision cases because the implants have either degraded or can simply be drilled through. However, although biodegradable materials have been attractive for many years, they have been linked to limitations such as breakage during insertion due to brittleness of the material,8,9 tissue reactions due to poor material quality or too fast or uncontrolled degradation (e.g., polyglycolic acid),10,11 or too slow degradation offering no real advantage over metal implants (e.g., poly-L-lactic acid implants have been documented to take more than 4 years to degrade).10,12–15 It is obvious that as a result of these observations, the material properties have been identified to play a critical role, and manufacturers have thus been challenged to further develop and optimize the chemical compositions of biodegradable implants. Whether the biodegradable interference screws are actually finally replaced by bone or by some other tissue remains controversial.16–20 As a matter of fact, according to a recent study by Tecklenburg et al,21 even the recently

introduced composite screws containing osteoconductive materials such as hydroxyapatite and tricalcium phosphate do not degrade in 2 years in vivo and thus cannot be replaced by bone. This clearly demonstrates the need for more optimal materials that degrade faster but are still controlled enough not to cause any clinically significant inflammatory or foreign body reactions. In addition, the material should be strong enough not to break during screw insertion and should provide adequate fixation strength during the healing period. A number of biodegradable polymers have been approved for safe internal use and have been used in surgical applications for the past 30 years, initially as suture materials. Each polymer has its material-specific properties, and an implant created from a single type of polymer is naturally limited by those properties. This explains some of the problems observed with the first-generation biodegradable implants. For example, polyglycolic acid (PGA) is strong but very fast to degrade; poly-L-lactic acid (PLLA) is strong but brittle and slow to degrade; whereas trimethylene carbonate (TMC) is rather weak but elastic like rubber. Copolymer blending is a novel manufacturing method developed in an attempt to combine the desired properties of different polymers and, by doing so, to overcome the limitations of the previous biodegradable implants. By blending different copolymers it is possible to create a library of material recipes from which to select those of the appropriate strength, toughness, and degradation to meet specific

Improving Biodegradable Interference Screw Properties by Combining Polymers

FIG. 52-1 The Inion Hexalon biodegradable interference screw.

clinical requirements. A biodegradable interference screw made of degradable copolymers composed of L-lactic acid, D-lactic acid, and TMC (Inion Hexalon, Inion Oy, Tampere, Finland) (Fig. 52-1) was introduced in 2002 and has since been studied both biomechanically and clinically. According to a recent preclinical sheep study, this copolymer blend fully degrades in 2 years in vivo without causing any clinically significant inflammatory, foreign body, or other tissue reactions.22

BIOMECHANICAL RESULTS Fixation Strength Fixation strength of the ACL graft is commonly considered to be the weakest link of ACL reconstruction. A three-part biomechanical study was carried out to study the fixation strength of the new biodegradable copolymer interference screw (Inion Hexalon) and to evaluate its suitability for ACL reconstruction by comparing it with the previously clinically used interference screws.23 In the first part, the initial soft tissue graft fixation strength of the copolymer screw was compared with that of a conventional metal interference screw (Acufex Softsilk). In the second part of the study, the initial soft tissue graft fixation strength of the copolymer screw was compared with that of another biodegradable interference screw (Bionx SmartScrew). In the third part of the study, the initial bone–tendon–bone graft fixation strength of the copolymer screw was compared with that of another commercially available biodegradable interference screw (Linvatec Bioscrew). Tibial bone tunnels were created in fresh skeletally mature porcine cadaver tibiae. A porcine ACL soft tissue graft

52

model previously described and used by Ishibashi et al24 and Harding et al25 was used in Parts I and II. Porcine patellar tendons were cut approximately 8 cm distal from their patellar insertion and left attached to the patellae. The free end of each patellar tendon was sutured using the running baseball stitch and thereafter fixed into tibial bone tunnel with an interference screw. In Part III, porcine bone–patellar tendon–bone grafts were prepared by obtaining a tibial bone block. The graft end with the tibial bone block was fixed into the tibial bone tunnel, and the maximum screw insertion torque was determined with a digital torquemeter connected to the screwdriver. The patellae were left intact to enable easy and rigid fixation to the mechanical testing machine (Lloyd LR 5K, J.J. Lloyd Instruments). The biomechanical tests were performed strictly according to the previously described single-cycle load-to-failure protocol of Kousa et al.7 The specimens were first subjected to a 50N preload for 1 minute. Thereafter, vertical tensile loading parallel to the long axis of the bone tunnel was performed at a rate of 50 mm/min until failure and the yield load, maximum failure load, and mode of failure were determined. In Part I (N ¼ 13), the average yield loads for the copolymer screw and metal screws were 491
154N and 418
77N, respectively (P ¼ 0.15). The average maximum failure loads were 548
130N and 453
94N, respectively (P ¼ 0.04). Although the average maximum failure load for the biodegradable screw group was significantly higher than that observed for the metal screw group, no significant difference was found in the more clinically relevant yield load values. The mode of failure was almost entirely graft slippage past the screw in both study groups, although also some graft laceration (partial rupture) and “graft stretching” were observed in the metal screw group, mainly at the screw–graft interface. In Part II (N ¼ 8), the average yield load for the copolymer screw was 501
122N and for the SmartScrew, 386
79N (P ¼ 0.05). The average maximum failure loads were 563
109N and 536
128N, respectively (P ¼ 0.65). The mode of failure was graft slippage past the screw in both study groups. In Part III, the average maximum insertion torque for the copolymer screw (N ¼ 8) was 1.9
0.7 Nm; for the Bioscrew (N ¼ 4), 1.5
0.6 Nm (P ¼ 0.32). The average yield loads for the copolymer screw and Bioscrew were 901
262N and 795
524N, respectively (P ¼ 0.77). The average maximum failure loads were 926
259N and 800
516N, respectively (P ¼ 0.72). All tested specimens in Part III failed by bone block pullout. One Bioscrew broke in Part III during insertion. No copolymer screw breakage was observed in this study. Based on these biomechanical results, the new biodegradable copolymer screw provides initial fixation strength similar to the other previously used biodegradable and conventional metal interference screws. 387

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Torsional Strength Screw breakage due to applied torsional forces during screw insertion rather than postoperative failure of graft fixation is the most common failure mode of biodegradable interference screws. The torsional strength of the interference screw is largely determined by the design of the screwdriver recess (socket) and the material of the screw. To test the torsional strength of the new biodegradable copolymer screw, a torsional strength study was performed according to the testing protocol of Costi et al.8,26 Six 7-  20-mm copolymer interference screws (Inion Hexalon) were mounted in a 10-mm layer of polyurethane resin, leaving the proximal 10 mm of the screws unembedded. This mounting reproduced the failure scenario observed in vivo, in which only part of the screw length has been inserted and becomes jammed in bone. Torque was applied manually with a digital electronic torque meter (Torqueleader TSD 350, MHH Engineering) mounted on the screwdriver. The same person applied torque in all cases in an attempt to provide a constant rate of application as well as compression on the screw. Care was taken to ensure that the application of torque was performed without associated bending or excessive compression. The maximum insertion torque was recorded, and the mode of failure was visually observed. In addition, to further investigate the failure of the screw, one screw was fixed into the 7-  20-mm screw cavity of the injection mold and torque was applied manually with a presettable torque wrench until failure. A desirable outcome of screw advancement through the polyurethane resin, rather than a failure of the screw or instrument, occurred with all test samples. The mean maximum insertion torque measured during screw penetration into the resin was 2.4
0.3 Nm. When the screw was fixed into the injection mold, no failure was observed at torque values between 0 and 5 Nm. When clinically irrelevant torque of more than 5 Nm was applied, the screwdriver shaft failed by rotational bending approximately 20 mm from the tip of the driver. Costi et al8 previously tested 12 different biodegradable interference screws using the same protocol. In their study, the only screws observed to continue screwing into the resin with no subsequent failure were the majority of the 7-mm PLLA Linvatec Bioscrews. In our study, all tested Inion Hexalon copolymer screws could be advanced through the resin without failure. In our additional test in which the screw was fixed into its injection mold to determine the ultimate failure point, the failure occurred first after a torque of more than 5 Nm was applied, again not by screw breakage but by bending of the metallic screwdriver shaft. Based on the previous observations made by Costi et al,8 this failure torque is above the clinically relevant

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insertion torques and the failure torques of most commercially available biodegradable interference screws.

Strength Retention To investigate the effect of hydrolytic degradation on the mechanical properties of the Inion Hexalon copolymer screws over time, screw compression tests were performed after 24 hours and 4, 8, and 12 weeks of incubation of 6-  20-mm and 7-  20-mm screws in phosphate buffer solution at 37 C (N ¼ 4/time point).27 In the compression test, each screw was set flat between the compression plates and loaded with a constant speed of 5 mm/min until failure (Zwick Z020, Zwick GmbH, Ulm, Germany). In the compression test, both screws retained more than 80% of their initial mechanical strength as long as 12 weeks.

CLINICAL RESULTS Clinical Experience In our clinical work, we have used these new biodegradable interference screws made of degradable copolymers composed of L-lactic acid, D-lactic acid, and TMC (Inion Hexalon) for ACL reconstruction for more than 4 years. During this period, more than 400 of these screws have been inserted to patients, and only one screw breakage has occurred during screw insertion. In this particular case, the screwdriver broke first, which was the reason for the screw breakage. These screws can be used both with single-bundle and double-bundle technique when performing ACL reconstruction.28,29

Prospective Randomized Clinical Trial We have done a prospective randomized clinical trial using either biodegradable screw or metallic screw in fixation of the ACL reconstruction with a hamstring autograft.29 In this study, 55 patients were randomized to either metallic interference screw (Timoni, Finland) (N ¼ 26) or biodegradable screw fixation (Inion Hexalon) (N ¼ 29) in ACL reconstruction with hamstring tendons. The evaluation methods were clinical examination, KT-1000 arthrometer (MEDmetric Corporation, San Diego, CA) measurements,30 radiographic evaluation, MRI, and International Knee Documentation Committee (IKDC)31 as well as Lysholm32 knee scores. There were no differences between the study groups preoperatively. For the minimum of 1-year follow-up (range 12–19 months), 23 patients of the metallic interference screw group and 26 patients of the

Improving Biodegradable Interference Screw Properties by Combining Polymers biodegradable screw group were available (90%). The evaluation methods disclosed no statistical differences between the groups at the follow-up examinations. However, the results were significantly better at the follow-up than preoperatively, in both groups. Kaeding et al33 have reported similar results in their prospective randomized study comparing biodegradable and titanium interference screw in fixation of the bone–patellar tendon–bone autograft for the ACL reconstruction. During the follow-up of our study, three revision ACL reconstructions had to be performed (two in the biodegradable screw group and one in the metallic screw group) because of new knee trauma. No other complications were found with these patients. The revision in the biodegradable screw group 8 months after the primary operation showed that the biodegradable screw was already soft. The other revision performed 18 months after primary surgery showed that the biodegradable screw was almost totally absorbed. The revision ACL reconstructions with these patients were easy to perform because we did not have to remove the screws at all. In the case in which the screw was soft but not totally absorbed yet, we simply drilled through it and created a 1 mm wider tunnel for the new graft. In addition, with another patient, the second-look arthroscopy showed that the biodegradable screw was totally absorbed 2 years after the primary operation (Fig. 52-2).

Magnetic Resonance Imaging Sixteen patients (10 patients in the biodegradable screw group and six in the metallic screw group) of our prospective

52

randomized study have been evaluated by MRI examination at a mean follow-up of 27 months (range 24–31 months). According to this evaluation, we have found that all the biodegradable screws (Inion Hexalon) were absorbed totally at the follow-up (Fig. 52-3). The MRI images appear to show that the bone tunnels are filled with fibrous tissue with signal intensity similar to that of the intraarticular ACL graft. However, because no histological analysis could be carried out in these human patients, no final conclusions regarding the tissue type that finally replaces the screw can be drawn at this point. The follow-up of these patients has been planned to continue for a minimum of 5 years postoperatively. The fact that the screws used in our study had been absorbed in 2 years is contradictory to the finding in the previous studies of Ma et al14 and Radford et al.15 They found that the biodegradable screws they used did not absorb in even 2 to 4 years. The explanation for this difference seems logical: the materials of these screws are different. In our study, we used biodegradable screws made of copolymers composed of L-lactic acid, D-lactic acid, and TMC, whereas in the studies of Ma et al14 and Radford et al,15 PLLA interference screws were used. However, two of our patients in the biodegradable screw group had some tunnel enlargement or cyst of the tunnel at the 2-year follow-up. One was in the tibial side, and another was in the femoral side (see Fig. 52-3, B). In these cases, the enlargement was only 2 to 3 mm when the width of the normal tunnel was compared. With all patients, the mean widths of the femoral and tibial tunnels were 10 mm (range 7–12 mm) and 10 mm (range

FIG. 52-2 A, The Inion Hexalon biodegradable interference screw at the operation during the screw insertion into the femoral tunnel. B, The same knee 2 years after the anterior cruciate ligament (ACL) reconstruction. The screw has totally absorbed, and the ACL graft is intact. However, there is some tunnel enlargement in front of the graft.

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Anterior Cruciate Ligament Reconstruction

FIG. 52-3 A, Magnetic resonance imaging (MRI) changes 4 months after anterior cruciate ligament (ACL) reconstruction with the Inion Hexalon biodegradable interference screw fixation on the femoral side. The screw is still visible (white circle in front of the hamstring graft). B, MRI changes 24 months after ACL reconstruction with the Inion Hexalon biodegradable interference screw fixation on the femoral side. The screw has absorbed, but there is some tunnel enlargement in front of the hamstring graft (the graft is the black circle in the posterior part of the femoral tunnel).

8–14 mm), respectively. No difference was found between the biodegradable and metallic screw groups. Previously in the literature, tunnel enlargement has been reported after using biodegradable fixation methods, as well as after using other fixation methods such as metallic screws and especially Endobutton fixation.14,33–35 However, the clinical importance of the tunnel enlargement still remains controversial. Theoretically, if the tunnel enlargement were large, it could be a problem when performing the revision ACL reconstruction. However, with our patients, the tunnel enlargement was so minimal that no problem would be expected later in the event that revision ACL surgery is needed. In fact, there were no difficulties in performing the revision ACL reconstruction with the two patients who underwent a revision ACL surgery in the biodegradable screw group of our study.

390

CONCLUSIONS The new copolymer screw provides fixation strength similar to that of other interference screws but has higher torsional strength than most of the previous biodegradable screws. The 1-year clinical results of this biodegradable screw are equivalent with those of conventional metal interference screws. In addition, this screw seems to degrade fully in 2 years without causing any clinically significant inflammatory, foreign body, or other adverse tissue reactions. This is important because the screw cannot be replaced by bone before it has degraded. However, further studies and longer clinical follow-up are needed before any final conclusions can be drawn and to evaluate whether the screw is finally replaced by bone.

Improving Biodegradable Interference Screw Properties by Combining Polymers

References 1. Colombet P, Allard M, Bousquet V, et al. Anterior cruciate ligament reconstruction using four-strand semitendinosus and gracilis tendon grafts and metal interference screw fixation. Arthroscopy 2002;18:232–237. 2. Ejerhed L, Kartus J, Sernert N, et al. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with a two-year follow-up. Am J Sports Med 2003;31:19–25. 3. Pinczewski LA, Deehan DJ, Salmon LJ, et al. A five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:523–536. 4. Scranton PE, Bagenstose JE, Lantz BA, et al. Quadruple hamstring anterior cruciate ligament reconstruction: a multicenter study. Arthroscopy 2002;18:715–724. 5. Shaieb MD, Kan DM, Chang SK, et al. A prospective randomized comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:214–220. 6. Kousa P, Järvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 7. Kousa P, Järvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 8. Costi JJ, Kelly AJ, Hearn TC, et al. Comparison of torsional strengths of bioabsorbable screws for anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:575–580. 9. Smith CA, Tennent TD, Pearson SE, et al. Fracture of Bilok interference screws on insertion during anterior cruciate ligament reconstruction. Case report. Arthroscopy 2003;19:E74. 10. Andriano KP, Pohjonen T, Tormala P. Processing and characterization of absorbable polylactide polymers for use in surgical implants. J Appl Biomater 1994;5:133–140. 11. Böstman OM, Pihlajamäki HK. Adverse tissue reactions to bioabsorbable fixation devices. Clin Orthop 2000;371:216–227. 12. Bergsma JE, de Bruijn WC, Rozema FR, et al. Late degradation tissue response to poly(L-lactide) bone plates and screws. Biomaterials 1995;16:25–31. 13. Böstman O, Pihlajamäki H. Clinical biocompatibility of biodegradable orthopaedic implants for internal fixation: a review. Biomaterials 2000;21:2615–2621. 14. Ma CB, Francis K, Towers J, et al. Hamstring anterior cruciate ligament reconstruction: a comparison of bioabsorbable interference screw and Endobutton-post fixation. Arthroscopy 2004;20:122–128. 15. Radford MJ, Noakes J, Read J, et al. The natural history of a bioabsorbable interference screw used for anterior cruciate ligament reconstruction with a 4-strand hamstring technique. Arthroscopy 2005;21:707–710. 16. Fink C, Benedetto KP, Hackl W, et al. Bioabsorbable polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: a prospective computed tomography-controlled study. Arthroscopy 2000;16:491–498. 17. Lajtai G, Noszian I, Humer K, et al. Serial magnetic resonance imaging evaluation of operative site after fixation of patellar tendon graft with bioabsorbable interference screws in anterior cruciate ligament reconstruction. Arthroscopy 1999;15:709–718. 18. Lajtai G, Schmiedhuber G, Unger F, et al. Bone tunnel remodeling at the site of biodegradable interference screws used for anterior

19.

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30. 31.

32.

33.

34.

35.

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cruciate ligament reconstruction: 5-year follow-up. Arthroscopy 2001;17:597–602. Morgan CD, Gehrmann RM, Jayo MJ, et al. Histologic findings with a bioabsorbable anterior cruciate ligament interference screw explant after 2.5 years in vivo. Case report. Arthroscopy 2002;18:E47. Weiler A, Hoffmann RFG, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135. Tecklenburg K, Burkart P, Hoser C, et al. Prospective evaluation of patellar tendon graft fixation in anterior cruciate ligament reconstruction comparing composite bioabsorbable and allograft interference screws. Arthroscopy 2006;22:993–999. Nieminen T, Rantala I, Hiidenheimo I, et al. Degradative and mechanical properties of a novel resorbable plating system during a 3-year follow-up in vivo and in vitro. J Mater Sci Mater Med 2007;18. Nurmi JT, Suuriniemi N. The fixation strength of the biodegradable Hexalon interference screw. The 12th Congress of European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA), Innsbruck, Austria, 2006. Book of Abstracts: p 234 [poster]. Ishibashi Y, Rudy TW, Livesay GA, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system. Arthroscopy 1997;13:177–182. Harding N, Barber FA, Herbert MA. The effect of the EndoPearl on soft-tissue graft fixation. J Knee Surg 2002;15:150–154. Nurmi JT, Ahvenjärvi P, Suuriniemi N. Torsional strength of a new biodegradable interference screw. The 12th Congress of European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA), Innsbruck, Austria, 2006. Book of Abstracts: p 233 [poster]. Väänänen P, Nurmi JT. The biomechanical properties of a biodegradable 6-mm interference screw. Podium presentation at the European Conference on Biomaterials (ESB 2006), Nantes, France, 2006. Järvelä T. Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a prospective, randomized clinical study. Knee Surg Sports Traumatol Arthrosc 2007;15:500–507. Järvelä T, Järvinen M. Anterior cruciate ligament reconstruction with a hamstring graft: prospective, randomized clinical study using metallic or bioabsorbable screw in fixation. Podium presentation at the 12th Congress of European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA), Innsbruck, Austria, 2006. Book of Abstracts: p 55. Daniel DM, Malcom LL, Losse G, et al. Instrumented measurement of anterior laxity of the knee. J Bone Joint Surg 1985;67A:720–726. Hefti F, Drobny T, Hackenbusch W, et al. Evaluation of knee ligament injuries: the OAK and IKDC forms. In Jakob RP, Staubli H-U (eds). The knee and the cruciate ligament. Berlin, 1990, Springer, pp 134–139. Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of scoring scale. Am J Sports Med 1982;10:150–154. Kaeding C, Farr J, Kavanaugh T, et al. A prospective randomized comparison of bioabsorbable and titanium anterior cruciate ligament interference screw. Arthroscopy 2005;21:147–151. Buelow JU, Siebold R, Ellermann A. A new biocortical tibial fixation technique in anterior cruciate ligament reconstruction with quadruple hamstring graft. Knee Surg Sports Traumatol Arthrosc 2000;8:218–225. Jansson KA, Harilainen A, Sandelin J, et al. Bone tunnel enlargement after anterior cruciate ligament reconstruction with the hamstring autograft and Endobutton fixation technique. A clinical, radiographic and magnetic resonance imaging study with 2 years follow-up. Knee Surg Sports Traumatol Arthrosc 1999;7:290–295.

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53 CHAPTER

Kazunori Yasuda

PART J GRAFT TENSIONING

Graft Tensioning in Anterior Cruciate Ligament Reconstruction INTRODUCTION The final outcome of anterior cruciate ligament (ACL) reconstruction depends on various implantation variables. Of these variables, graft tensioning is an especially important one because it is controlled by a surgeon during surgery. Essentially, graft tensioning is a procedure in which a certain degree of initial tension is applied to the graft at a selected angle of knee flexion. In order to maintain the applied tension, however, it is necessary to fix the graft to bones with some artificial materials immediately after tensioning. Therefore, clinically, graft tensioning and graft fixation are regarded as one combined procedure in ACL reconstruction. In addition, we should distinguish between the initial tension, which is defined as a tension applied to the graft at a selected angle of knee flexion during surgery, and the postoperative graft tension that exists at each period after surgery. These tensions are extremely different in the late phase after ACL reconstruction. The former is important because it strongly affects the latter, but the latter is more important because it actually affects graft remodeling and knee functions after ACL reconstruction. On the basis of clinical experience, pioneers of current ACL reconstruction procedures preferred to apply relatively high initial tension to not only the doubled pes tendon autograft but also the patellar tendon autograft at the time of fixation.1–4 For example, Clancy et al1 performed ACL reconstruction using the distally stacked and proximally free central third of the

392

patellar tendon as an autograft and recommended that the patellar bone block be pulled with three sutures through the femoral tunnel as far as it would go within the tunnel. On the other hand, a number of in vitro and in vivo experimental studies suggested that a high initial tension had detrimental effects not only on the graft but also on the knee after ACL reconstruction. Some recent studies, however, reported that a high initial tension was better than a low initial tension in simulation of a middle- or long-term effect. Thus there has been considerable disagreement on the effects of initial graft tension among the previous studies. It has been necessary therefore to conduct randomized clinical trials on the effect of initial graft tension on the outcome after ACL reconstruction. At the present time, four articles on the effect of initial graft tension on the clinical outcome are available for review. In this chapter, the author reviews recent experimental and clinical studies on the effect of graft tensioning during ACL reconstruction on the graft and the ACL reconstructed knee and explains what has and has not been clarified at the present time.

IN VITRO BIOMECHANICAL STUDIES ON GRAFT TENSIONING The Effect of the Initial Tension on the Tension-Flexion Curve In the normal knee, tension in the normal ACL decreases with knee flexion from the maximum

Graft Tensioning in Anterior Cruciate Ligament Reconstruction value obtained at 0 degrees to the minimum value near 30 degrees and then slightly increases with further flexion.5,6 This relationship between the ACL tension and the knee flexion angle is well known as a tension-flexion curve. In ACL reconstruction, the initial tension is defined as a tension applied to the graft at a selected angle of knee flexion during surgery. Then we should know the effect of the initial tension on the tension-flexion curve in ACL reconstruction. In vitro biomechanical studies5,7 reported that in the standard single-bundle ACL reconstruction procedures, increase of the initial tension applied at some angle of knee flexion increased the graft tension by a constant magnitude at every flexion angle during knee motion and that consequently the shape of the tension-flexion curve was not changed (Fig. 53-1). Namely, it means that an increase of the initial graft tension at 30 degrees of knee flexion results in an increase of the graft tension at every knee flexion angle. In 2001, Fleming et al8 measured the laxity in nine different tensioning conditions: three tension magnitudes (30, 60, and 90N), each applied with the knee at three angles (30, 60, and 90 degrees), in a goat ACL reconstruction model using a bone–tendon–bone (BTB) graft. They stated that both the graft tension and the knee angle produced significant changes on anteroposterior laxity values. These in vitro studies indicated that both the initial tension value and the knee flexion angle at the time of tensioning and fixation are critical in the ACL reconstruction. In the standard ACL reconstruction procedures, when a surgeon applies a certain “initial” tension value at about 30 degrees of knee flexion, a graft tension value obtained at more extension positions or more flexion positions is greater than the initial tension value.7 Conversely, when a surgeon

100

Tension (N)

80 60 40 20 0
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30 40 50 60 70 Flexion angle (deg) 22 N

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90 100

33 N

FIG. 53-1 In the standard single-bundle anterior cruciate ligament (ACL) reconstruction procedures, increase of the initial tension applied at some angle of knee flexion increased the graft tension by a constant magnitude at every flexion angle during knee motion. (From Fleming B, Beynnon BD, Johnson RJ, et al. Isometric versus tension measurements. A comparison for the reconstruction of the anterior cruciate ligament. Am J Sports Med 1993;21:82–88.)

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applies a certain initial tension value at the full extension position of the knee, graft tension values at flexion positions are lower than the initial tension value. Clinically, a number of surgeons have preferred to fix the graft at approximately 30 degrees of knee flexion in order to avoid an insufficient tension after surgery, specifically for the hamstring tendon graft. On the other hand, recently many surgeons who perform ACL reconstruction with the BTB graft have preferred to fix the graft at the full extension position to avoid postoperative flexion contracture of the knee due to overtensioning of the graft.

Relaxation of Graft Tension after Surgery In vitro biomechanical studies have shown that viscoelastic creep of the graft causes relaxation of graft tension. Howard et al9 quantified viscoelastic creep in the BTB graft using both an in vivo and an in vitro model. In the in vivo model, 10-mm BTB grafts were elongated by 14.0% after 89N was applied for a minimum of 4 minutes. In the in vitro model, grafts were elongated by 10.1% after 89N was applied for 15 minutes. This study highlights the importance of the time for preconditioning the graft before grafting. The author and his colleagues10–12 reported that more obvious relaxation of graft tension occurred due to elongation of a bone–graft–bone complex that is composed of bones, tendon grafts, and all artificial materials to be used for graft fixation. They measured the influence of 5000 cycles of submaximal cyclical displacement upon the tension of various types of the bone–graft–bone complex after ACL reconstruction. For example, Yamanaka et al10 showed that initial tension of 80N applied to the four-strand flexor tendon graft tethered to the screw post with a suture was reduced to 0N after 5000 cycles of 2-mm stretching, while the same initial tension applied to the BTB graft fixed with interference screws was reduced to 17N (Fig. 53-2). In addition, the relaxation rate in the BTB graft fixed with interference screws was less than that in the BTB graft fixed with sutures and screw posts, whereas the relaxation rate in the flexor tendon graft fixed with sutures and screw posts was greater than that in the BTB graft fixed with the sutures and screw points (see Fig. 53-2). Boylan et al13 applied an initial tension of 68N, 45N, and 23N to the hamstring graft at 30 degrees of flexion, fixed with a suture and post technique. After 1000 cycles of knee motion between 0 and 90 degrees, the tension in the graft decreased to 34.5N, 16.8N, and 15.4N, respectively. Arnold et al14 applied 40N initial tension to the BTB graft at 20 degrees of flexion in ACL reconstruction with cadavers, fixed with interference screws. The graft tension at 0 degrees of flexion dropped from 208N, or by 41% at 500 cycles. Anterior laxity increased from þ1.4 to þ2.8 mm by 500 cycles. 393

Anterior Cruciate Ligament Reconstruction

Peak load at each cycle (N)

300

Mean  SD (n5 for each group) *p0.01 (vs 1st cycle)

250 *

200

*

*

*

*

150 100 50

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

0 1

1000

2000 3000 Cycle

4000

5000

Valley load at each cycle (N)

A Group A Group B Group C Group D

60 50 40 30 *

20

*

10 0 1

* 1000

* *

*

*

*

*

*

* * 5000

* * 2000 3000 Cycle

* 4000

B FIG. 53-2 The peak and valley loads during cyclic stretching. Group A, Bone–tendon–bone (BTB) graft fixed with interference screws. Group B, BTB graft fixed with the suture-post technique. Group C, Multistrand flexor tendon graft fixed with the tape-staple technique. Group D, Multistrand flexor tendon graft fixed with the sutures-tied-over-a-button technique. The initial tension of 80N applied to the BTB graft fixed with interference screws was reduced to 17N. In addition, the relaxation rate in the BTB graft was different, depending on the fixation devices. (From Yamanaka M, Yasuda K, Nakano H, et al. The effect of cyclic displacement upon the biomechanical characteristics of anterior cruciate ligament reconstructions. Am J Sports Med 1999;27:772–777.)

These studies suggested that the initial tension applied at the time of fixation is rapidly relaxed after surgery by repetitive submaximal loading in all ACL reconstruction procedures. In addition, the relaxation rate depends on a combination of a graft and all artificial materials used for graft fixation. In graft tensioning in each ACL reconstruction, therefore, a surgeon should determine an appropriate initial tension value in each procedure, taking into account a specific degree of the postoperative graft relaxation. However, a significant problem is that a degree of the postoperative graft relaxation in each surgery has not been precisely clarified yet.

Effects of a High or Low Initial Tension on the Graft and the Knee A number of in vitro studies with cadaver knees, which simulated conditions immediately after ACL reconstruction, 394

showed that an increase of ACL tension decreased the degree of anterior translation of the tibia to the femur.7,15–17 Melby et al17 described that an 18N tension applied to the graft at 30 degrees of knee flexion restored the laxity and stiffness most closely resembling that of the intact knee, without inducing significant abnormal laxities, but that tensions greater than 54N overconstrained the knee. Several in vitro studies warned that overtensioning might result in restriction in range of motion and graft failure.18–20 For example, Nabors et al19 showed that when a high initial tension was applied to the BTB graft at 30 degrees of knee flexion, loss of knee extension frequently occurred after surgery. Graf et al20 indicated that a high tension induced wear-related graft failure. Eager et al21 reported that a high initial tension induced posterior subluxation of the tibia with respect to the femur, specifically when a graft having low stiffness was used. Thus the just-described in vitro studies recommended a low initial tension be applied to the graft in ACL reconstruction. However, a criticism of these in vitro studies is that they did not take the graft relaxation into account. Beynnon et al15 reported that because the tension applied on a graft at the time of fixation was acutely decreased by creep elongation of an autograft or transposition of an autograft in the bone tunnel, insufficient initial tension applied on the graft during surgery might result in slackness of a reconstructed ligament tissue. In 2002, Numazaki et al12 stretched a few types of the femur–graft–tibia complex by 2 mm for 5000 cycles, after an initial tension of 20N, 80N, and 140N was applied for 2 minutes. In a four-strand flexor tendon graft with Endobutton fixation, the peak load values at the 5000th cycle were 17N, 40N, and 77N, respectively. The researchers stated that applying an initial graft tension of approximately 80N did not appear to be too high for the hamstring tendon graft with Endobutton fixation after graft relaxation. In 2003, Boylan et al13 applied an initial tension of 68N, 45N, and 23N to the hamstring graft at 30 degrees of flexion, fixed with a suture and post technique. The average laxity showed 6.0 mm, 8.1 mm, and 8.9 mm, respectively. After 1000 cycles of knee motion between 0 and 90 degrees, the tension in the graft decreased to 34.5N, 16.8N, and 15.4N, respectively, and the average laxity increased to 7.8 mm, 10.5 mm, and 10.3 mm, respectively (Fig. 53-3). They concluded that to restore anterior translation to within 3 mm of the native ACL condition after cyclical loading, a relatively high tension of approximately 68N was required using this fixation technique. Thus among previous in vitro studies, there have been controversies on the effect of high initial tension on the graft and the knee. However, these in vitro studies that took the postoperative graft relaxation into account suggest the strong possibility that an appropriate degree of high initial tension may not provide such detrimental effects to the graft

Graft Tensioning in Anterior Cruciate Ligament Reconstruction 15

Before motion

Anterior laxity (mm)

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53

IN VIVO STUDIES WITH ANIMAL ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION MODELS Essential Effects of Tension on the Graft Properties

10

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0 23-N group

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FIG. 53-3 An initial tension of 68N, 45N, and 23N was applied to the hamstring graft at 30 degrees of flexion and fixed with a suture and post technique. After 1000 cycles of knee motion between 0 and 90 degrees, the average anterior laxity in the 68N group was significantly less than that the other two groups. (From Boylan D, Greis PE, West JR, et al. Effects of initial graft tension on knee stability after anterior cruciate ligament reconstruction using hamstring tendons: a cadaver study. Arthroscopy 2003;19:700–705.)

and the knee compared with those shown in the studies that did not take this into account.

Clinical Relevance from the Previous In Vitro Studies We should note that there are some agreements in the previous in vitro studies. First, an increase in graft tension decreases the degree of anterior translation of the tibia to the femur. Second, a high initial tension applied to the graft overconstrains the knee at least immediately after surgery. Third, relaxation of graft tension commonly occurs in a relatively early phase after surgery, and the degree and velocity of the graft relaxation depend on a combination of the graft and all artificial materials used for graft fixation. Fourth, although behaviors of the ACL reconstructed knee have been considered to be graft specific,16 we should now recognize that the behavior of the ACL reconstructed knee is graft fixation device–specific. However, we also should note that there is considerable disagreement among the clinical messages from the previous in vitro studies on clinical ACL reconstruction. The relaxation of the graft tension after surgery may be an important key to understand the causes of this disagreement. Also, we have found some serious limitations in the in vitro studies. Thus, in vivo studies with animal ACL reconstruction models have been necessary.

Before discussing the effect of graft tensioning on the outcome after ACL reconstruction, we should understand the essential effect of tension on the tendon graft. The author and his associates have performed a series of in vivo studies on the effect of stress on the in situ frozen-thawed patellar tendon and ACL, which are idealized extraarticular and intraarticular autograft models, respectively.22–26 Regarding the effect of low stress, Ohno et al22 and Majima et al23 demonstrated that reduction of stress dramatically reduced the mechanical properties of the in situ frozen-thawed rabbit patellar tendon at 3, 6, and 12 weeks after surgery. Regarding the effect of high stress, Tohyama and Yasuda25 reported that enhancement of stress also reduced the mechanical properties of the in situ frozen-thawed rabbit patellar tendon at 6 weeks after surgery. Also, Katsuragi et al26 applied a high tension to the in situ frozen-thawed canine ACL in which the applied high tension was proven to be continuously maintained in the experimental period. This study demonstrated that an unphysiologically high tension significantly deteriorated the mechanical properties of the in situ frozen canine ACL at 12 months after surgery when compared with physiological tension. These in vivo studies revealed the essential effects of stress to the tendon graft. Namely, continuous application of both excessively high and low initial tensions has detrimental effects on the graft. We should note that the latter is stronger than the former. However, we should recognize that the mechanical conditions surrounding the free tendon graft may be different from those in these scientific studies because an initially applied tension may be reduced to various degrees. Even in the idealized ACL reconstruction model with the canine in situ frozen-thawed ACL, the initial graft tension is chronically relaxed over time due to biological mechanisms.27

Effects of Initial Tension on Anterior Cruciate Ligament Reconstruction Models Regarding the effect of initial tension on knee stability, function, and pathology, Yoshiya et al28 investigated the effects of 1N and 39N initial loads on a canine ACL reconstruction model with a free patellar tendon graft. They observed poor vascularity and focal myxoid degeneration within the graft pretensioned with a load of 39N, but not within the graft with 1N of tension applied. Although they

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studies differ from those in human ACL reconstruction. Therefore it has been urgently necessary to conduct randomized clinical trials to determine the effect of initial tension in each type of ACL reconstruction.

RANDOMIZED CLINICAL TRIALS ON THE EFFECT OF INITIAL GRAFT TENSION ON THE OUTCOME AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Only four randomized clinical trials have been reported to evaluate the effect of initial graft tension on the outcome after ACL reconstruction. In 1997, Yasuda et al31 reported the first randomized clinical trial using 72 patients. They applied initial tension of 20N, 40N, and 80N to the doubled hamstring tendon graft at 30 degrees of knee flexion and examined clinical outcome at 2 years after ACL reconstruction. The average side-to-side anterior laxity was 2.1, 1.4, and 0.6 mm in the 20N, 40N, and 80N groups, respectively (Fig. 53-4). The postoperative laxity in the 80N group was significantly less than that in the 20N group. All the patients restored full range of knee motion. There were no significant differences in subjective clinical results and muscle strength among the groups. Based on this study, Kim et al32 recently investigated whether initial tension of more than 80N provided any detrimental effects on the knee with hamstring ACL reconstruction, using 48 patients. They applied three different initial tensions of 8, 12, and 15 kg to the hamstring graft at 30 degrees of knee flexion. The patients were observed 10

20N group 40N group

Side-to-side anterior laxity (mm)

detected no significant difference in the values for the ultimate failure load of the graft 3 months after reconstruction, they suggested that a high degree of tension might be detrimental to the patellar tendon autograft during surgical reconstruction of the ACL. Using the in situ frozen-thawed canine ACL model in which the applied high tension was proven to be continuously maintained in the experimental period, Katsuragi et al26 applied a high tension of 20N to the graft model. They demonstrated not only that an unphysiologically high tension significantly deteriorated the mechanical properties of the in situ frozen canine ACL at 12 months after surgery when compared with physiological tension, but also that it provided histological changes in the graft and mild cartilage degeneration at the same period. Namely, in the highly tensioned knee, ovoid and focal degenerative changes with a number of vacuoles were occasionally found in the matrix, and a small part of the articular cartilage surface showed mild softening and fibrillation in each knee, although neither meniscal tears nor tibiofemoral osteophyte formation was found. On the other hand, Labs et al29 determined the effect of initial graft tension (1N, 7.5N, 17.5N) on the biomechanical and histological behavior of the ACL graft using a rabbit model at 2, 8, and 32 weeks. The load at failure was 40.5% of the normal ACL at 1N, 45.1% at 7.5N, and 50.8% at 17.5N at 32 weeks postoperatively. They stated that higher initial graft tension resulted in improved histological and biomechanical parameters. In addition, pathological changes in the graft or cartilage damage due to overconstraining of the knee were not observed at the selected initial tensions. In 2003, Abramowitch et al30 performed a goat model study. They investigated whether the differences in knee stability, which were present immediately after ACL reconstruction with grafts fixed at low (5N) and high (35N) initial tension, remained after 6 weeks and whether the tensile properties of an ACL replacement graft were influenced by initial graft tension. Although the high initial graft tension could better replicate the normal knee kinematics at time-zero, these effects diminished during the early graft healing process. Further, the stiffness and ultimate load at failure of the graft were not significantly different between both reconstruction groups. Thus, concerning the effect of initial tension on the graft and the knee functions, we have found considerable disagreement among the in vivo studies with the animal models. The reasons may include the fact that postoperative biomechanical conditions surrounding the ACL graft are extremely different among the animal models. In vivo studies with animal models are valuable because we can receive an important message from each study concerning a specific focus related with the clinical field. However, we must say that the postoperative conditions in these in vivo experimental

80N group

8

6

4 * 2

0 Preoperation

Postoperation

FIG. 53-4 When an initial tension of 20N, 40N, or 80N was applied to the doubled hamstring tendon graft at 30 degrees of knee flexion, the average side-to-side anterior laxity in the 80N group was significantly less than that in the 20N group. (From Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:99–106.)

Graft Tensioning in Anterior Cruciate Ligament Reconstruction for 1 year or more after surgery. Postoperatively, the average side-to-side difference in anterior laxity was 1.3 mm in the 8-kg group, 2.1 mm in the 12-kg group, and 2.4 mm in the 15-kg group. The authors stated that there were no significant differences not only in the anterior laxity but also in subjective clinical results and knee extensor strength between the groups. However, we should note that the average laxity value in the 15-kg group was approximately twice as much as that in the 8-kg group. These two studies suggested that relatively high initial tension of approximately 80N reduces the postoperative anterior laxity of the knee joint after ACL reconstruction using the hamstring tendons. Any obvious detrimental effects were noted in these two trials, although long-term results were not known. Regarding ACL reconstruction with the BTB graft, van Kampen et al33 reported a randomized trial with 38 patients in 1998. They applied 20N or 40N tension to the BTB graft at 20 degrees of knee flexion and examined clinical outcome at 1 year after surgery. The side-to-side anterior laxity averaged 2.6 mm in the 20N group and 2.5 mm in the 40N group. They found no significant differences. On the other hand, in 2004 Nicholas et al34 reported a randomized trial using 49 patients. They fixed the graft at 45N or 90N at the knee extension position and examined the clinical outcome at an average of 20 months after surgery. The side-to-side anterior laxity difference was significantly greater in the patients in the low-tension group (average 3.0 mm) than in the high-tension group (average 2.2 mm) (Fig. 53-5). The five patients with abnormal anterior tibial displacement (greater than 5 mm side-to-side difference)

Low tension

Side-to-side difference (mm)

10

High tension

8

6

4

2

0 Before surgery

1 week

20 months

FIG. 53-5 When the graft was fixed at 45N or 90N at the knee extension position, the side-to-side anterior laxity difference was significantly greater in the patients in the low-tension group than in the high-tension group at an average of 20 months after surgery. (From Nicholas SJ, D’Amato MJ, Mullaney MJ, et al. A prospectively randomized double-blind study on the effect of initial graft tension on knee stability after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:1881–1886.)

53

were only in the low-tension group. The patients regained full range of knee motion. Knee outcome scores and hop test deficits were not different between groups. There is disagreement on the effect of initial graft tension on the knee stability between these two studies on ACL reconstruction with the BTB graft. Nicholas et al34 pointed out that the forces in van Kampen’s study33 were lower than the tensions routinely applied to the BTB graft by experienced surgeons during graft tensioning, that initial graft tension affects the restoration of knee stability, and that a graft tension of 45N was not sufficient for restoring knee stability. Thus at the present time, no consensus has been reached regarding the amount of graft tension needed to re-create normal knee mechanics after ACL reconstruction using each graft-device combination. However, we have found the following facts on the effect of initial tension in the four clinical studies. Namely, no studies reported that a low tension of less than 40N applied at 0 to 30 degrees of knee flexion was more beneficial to restore the nearly normal stability of the knee in the 1- to 2-year outcome after ACL reconstruction compared with a high tension of greater than 40 N. Also, no studies reported that a relatively high initial tension of approximately 80N, which overconstrained the knee immediately after surgery, provided detrimental effects to the knee function in the 1- to 2-year outcome. For example, the fact that postoperative range of knee motion was clearly not different between the high-tension and low-tension groups in each study demonstrated that the knee is not overconstrained at the follow-up period. It is of note that in the two studies with the hamstring or BTB graft, a relatively high initial tension of 80N or 90N was more beneficial than a relatively low tension of 20N or 45N in restoring the nearly normal stability of the knee in the 1- to 2-year outcome.31,34 This result may support the fact that current ACL reconstruction specialists prefer such degrees of high initial tension.35 According to Nicholas et al,34 two potential mechanisms are considered to explain why high tensions decreased the anterior laxity of the knee. The first potential mechanism is that tension of a ligament tissue reconstructed at the final follow-up examination may be increased depending on the degree of initial graft tension due to the fact that insufficient initial tension may result in slackness of a reconstructed ligament tissue, as the initial graft tension is acutely decreased by various causes.10–12,15 The second potential mechanism is that the stiffness and the strength of a reconstructed ligament tissue may be increased depending on the degree of initial graft tension because a low tension significantly reduces the mechanical properties of tendon autograft models.22,23 In the near future, we should be able to determine which mechanism is correct. In addition, further randomized clinical studies are required to reach consensus on this issue. 397

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References 1. Clancy WG, Nelson DA, Reider B, et al. Anterior cruciate ligament reconstruction using one-third of the patellar ligament, augmented by extra-articular tendon transfers. J Bone Joint Surg 1982;64A:352–359. 2. Jones KG. Reconstruction of the anterior cruciate ligament: a technique using the central one-third of the patellar ligament. J Bone Joint Surg 1963;45A:925–932. 3. Noyes FR, Butler DL, Paulos LE, et al. Intra-articular cruciate reconstruction. I: perspectives on graft strength, vascularization, and immediate motion after replacement. Clin Orthop 1983;172:71–77. 4. Zarins B, Rowe CR. Combined anterior cruciate-ligament reconstruction using semitendinosus tendon and iliotibial tract. J Bone Joint Surg 1986;68A:160–177. 5. Fleming B, Beynnon BD, Johnson RJ, et al. Isometric versus tension measurements. A comparison for the reconstruction of the anterior cruciate ligament. Am J Sports Med 1993;21:82–88. 6. Markolf KL, Gorek JF, Kabo JM, et al. Direct measurement of resultant forces in the anterior cruciate ligament. An in vitro study performed with a new experimental technique. J Bone Joint Surg 1990;72A:557–567. 7. Bylski-Austrow DI, Grood ES, Hefzy MS, et al. Anterior cruciate ligament replacements: a mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension. J Orthop Res 1990;8:522–531. 8. Fleming BC, Abate JA, Peura GD, et al. The relationship between graft tensioning and the anterior-posterior laxity in the anterior cruciate ligament reconstructed goat knee. J Orthop Res 2001;19:841–844. 9. Howard ME, Cawley PW, Losse GM, et al. Bone-patellar tendonbone grafts for anterior cruciate ligament reconstruction: the effects of graft pretensioning. Arthroscopy 1996;12:287–292. 10. Yamanaka M, Yasuda K, Nakano H, et al. The effect of cyclic displacement upon the biomechanical characteristics of anterior cruciate ligament reconstructions. Am J Sports Med 1999;27:772–777. 11. Numazaki H, Tohyama H, Yasuda K, et al. The effect of initial graft tension on mechanical behaviors of the femur-graft-tibia complex with anterior cruciate ligament reconstruction during cyclic loading. Am J Sports Med 2002;30:800–805. 12. Nakano H, Yasuda K, Tohyama H, et al. Interference screw fixation of doubled flexor tendon graft in anterior cruciate ligament reconstruction—biomechanical evaluation with cyclic elongation. Clin Biomech 2000;15:188–195. 13. Boylan D, Greis PE, West JR, et al. Effects of initial graft tension on knee stability after anterior cruciate ligament reconstruction using hamstring tendons: a cadaver study. Arthroscopy 2003;19:700–705. 14. Arnold MP, Lie DTT, Verdonschot N, et al. The remains of anterior cruciate ligament graft tension after cyclic knee motion. Am J Sports Med 2005;33:536–542. 15. Beynnon BD, Johnson RJ, Fleming BC, et al. The measurement of elongation of anterior cruciate-ligament grafts in vivo. J Bone Joint Surg 1994;76A:520–531. 16. Burks RT, Leland R. Determination of graft tension before fixation in anterior cruciate ligament reconstruction. Arthroscopy 1988;4:260–266. 17. Melby A III, Noble JS, Askew MJ, et al. The effects of graft tensioning on the laxity and kinematics of the anterior cruciate ligament reconstructed knee. Arthroscopy 1991;7:257–266.

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18. Gertel TH, Lew WD, Lewis JL, et al. Effect of anterior cruciate ligament graft tensioning direction, magnitude, and flexion angle on knee biomechanics. Am J Sports Med 1993;21:572–581. 19. Nabors ED, Richmond JC, Vannah WM, et al. Anterior cruciate ligament graft tensioning in full extension. Am J Sports Med 1995;23:488–492. 20. Graf BK, Henry J, Rothenberg M, et al. Anterior cruciate ligament reconstruction with patellar tendon. An ex vivo study of wear-related damage and failure at the femoral tunnel. Am J Sports Med 1994;22:131–135. 21. Eagar P, Hull ML, Howell SM. How the fixation method stiffness and initial tension affect anterior load-displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft. J Orthop Res 2004;22:613–624. 22. Ohno K, Yasuda K, Yamamoto N, et al. Effects of complete stress shielding on the mechanical properties and histology of in situ frozen patellar tendon. J Orthop Res 1993;11:592–602. 23. Majima T, Yasuda K, Yamamoto N, et al. Deterioration of mechanical properties of the autograft in controlled stress-shielded augmentation procedures. An experimental study with rabbit patellar tendon. Am J Sports Med 1994;22:821–829. 24. Tsuchida T, Yasuda K, Kaneda K, et al. Effects of in situ freezing and stress-shielding on the ultrastructure of rabbit patellar tendons. J Orthop Res 1997;15:904–910. 25. Tohyama H, Yasuda K. The effects of stress enhancement on the extracellular matrix and fibroblasts in the patellar tendon. J Biomech 2000;33:559–565. 26. Katsuragi R, Yasuda K, Tsujino J, et al. The effect of nonphysiologically high initial tension on the mechanical properties of in situ frozen anterior cruciate ligament in a canine model. Am J Sports Med 2000;28:47–56. 27. Mikami S, Yasuda K, Katsuragi R, et al. Reduction of initial tension in the in situ frozen anterior cruciate ligament. Clin Orthop Relat Res 2004;419:207–213. 28. Yoshiya S, Andrish JT, Manley MT, et al. Graft tension in anterior cruciate ligament reconstruction: an in vivo study in dogs. Am J Sports Med 1987;15:464–469. 29. Labs K, Perka C, Schneider F. The biological and biomechanical effect of different graft tensioning in anterior cruciate ligament reconstruction: an experimental study. Arch Orthop Trauma Surg 2002;122:193–199. 30. Abramowitch SD, Papageorgiou CD, Withrow JD, et al. The effect of initial graft tension on the biomechanical properties of a healing ACL replacement graft: a study in goats. J Orthop Res 2003;21:708–715. 31. Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:99–106. 32. Kim SG, Kurosawa H, Sakuraba K, et al. The effect of initial graft tension on postoperative clinical outcome in anterior cruciate ligament reconstruction with semitendinosus tendon. Arch Orthop Trauma Surg 2005;28:1–5. 33. van Kampen A, Wymenga AB, van der Heide HJ, et al. The effect of different graft tensioning in anterior cruciate ligament reconstruction: a prospective randomized study. Arthroscopy 1998;14:845–850. 34. Nicholas SJ, D’Amato MJ, Mullaney MJ, et al. A prospectively randomized double-blind study on the effect of initial graft tension on knee stability after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:1881–1886. 35. Cunningham R, West JR, Greis PE, et al. A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament. Arthroscopy 2002;18:983–988.

Tensioning Anterior Cruciate Ligament Grafts INTRODUCTION Graft selection, graft position, fixation, and postoperative rehabilitation are clearly implicated in the success and failure of anterior cruciate ligament (ACL) reconstruction. Tensioning of the ACL is another important factor in providing immediate and long-term stability in the reconstructed patient. Jones1 stated that tension applied to the ACL graft at the time of surgery should be enough to eliminate an anterior drawer sign but still allow a full range of motion. Excessive initial tension can lead to graft failure, fixation failure, loss of knee motion, excessively reduced anterior laxity, and cartilage degeneration.2–6 Lewis et al6 introduced the term overcorrected to describe the phenomenon in which the tibia was positioned posterior and externally rotated relative to the femur. Andersen and Jorgensen7 used a prosthetic ligament to study the consequence of overcorrected ACL reconstructions. These kinematic alterations result in increased graft forces at all flexion angles, increased forces in the posterior cruciate ligament (PCL), and alteration of the normal roll–glide mechanism during knee motion. Melby et al2 found that graft tension–related posterior tibial subluxation resulted in an increase in quadriceps force needed to achieve full knee extension and may lead to an extensor lag if quadriceps atrophy is present. As more sophisticated models of ACL tensioning have developed, efforts have focused on the effect of tension on the graft itself. The terminology can be confusing; terms such as preloading,

pretensioning, preconditioning, and initial tension have been used. For this text, pretensioning refers to any loading of the graft that is performed before the graft is pulled into the femoral and tibial bone tunnels. Preconditioning refers to the loading of the graft that is performed once the graft has been fixed within one of the tunnels (usually the femoral tunnel). The term initial tension refers to the tension in the graft after fixation within both tunnels. Initial tension affects the biology of the graft and is a time-dependent interplay of host incorporation and biomechanical forces. A number of factors affect graft tension, including initial tension (pretensioning and preconditioning), ligament length, graft isometry, tissue type, and fixation type (Fig. 54-1). For the purposes of this chapter, we will review the consequences of overtensioning the ACL graft both histologically and functionally, explore the factors in low-tension (bone–tendon–bone [BTB]) and high-tension (soft tissue) grafts, identify the ideal knee fixation angle, and provide suggestions for identifying tensioning problems and possible solutions. Historically, much debate has existed in the literature regarding these issues, with relatively few clinical studies focusing on graft tension; however, some consensus has been identified in recent years to lend clarity to this confusing topic.

54 CHAPTER

Lonnie E. Paulos

NATIVE ANTERIOR CRUCIATE LIGAMENT TENSION The goal of ACL reconstruction is to restore normal knee kinematics. Success requires a basic

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Ligament length

Isometry

Tissue type

Fixation type

Ultimate ligament tension FIG. 54-1 Factors affecting ultimate graft tension.

understanding of the forces affecting the normal ACL. Markolf et al8 and Wascher et al9 studied a series of loading experiments on cadaver specimens by isolating the bone plug that contained the ligament’s tibial insertion and attaching a load transducer. Passive extension of the knee generated forces in the ligament only during the last 10 degrees of extension, reaching 50 to 240N with hyperextension. Internal tibial torque generated greater forces in the ligament than did external tibial torque and increased as the knee was extended. The greatest forces (133–370N) were generated when 10 N/m of internal tibial torque was applied in hyperextension. A varus moment of 15 N/m generated forces of 94 to 177N at full extension, and a similar valgus moment generated a mean force of 56N independent of knee flexion. Active knee motion near extension substantially increases forces across the ACL. Paulos et al10 reported that lengthening of the ACL was observed during active extension from 40 degrees of knee flexion. Active quadriceps contraction imparts significant strain on the ACL. Arms et al11 showed that over the first 45 degrees of flexion, the quadriceps increased strain, whereas it decreased strain at flexion angles greater than 60 degrees. Beynnon et al12 studied the forces on the anteromedial bundle of various exercises. Isometric quadriceps contraction at 15 degrees of knee flexion elicited the highest peak strain (4.4%), followed by open chain flexion-extension with a 45N weight (3.8%) and a Lachman test (3.7%). Isometric quadriceps contraction at 30 degrees contributed significantly less strain (2.7%) to the ACL. More recent investigation has focused on the importance of both the anteromedial and posterolateral bundles in ACL function. Sakane et al13 examined in situ forces in nine human ACLs in response to applied anterior tibial loads at knee flexion angles of 0 to 90 degrees. Their results showed the magnitude of ACL force to be maximal with anterior tibial loads applied at 15 degrees of knee flexion, which differs slightly from Markolf’s earlier conclusions. The magnitude of force in the posterolateral bundle was larger than that in the anteromedial bundle at knee flexion angles between 0 and 45 degrees, reaching a maximum of 75N at 15 degrees of knee flexion under an anterior tibial load of 110N. The magnitude of force on the anteromedial bundle, in contrast, remained constant independently of flexion angle. They concluded that the magnitude of force 400

in the posterolateral bundle was significantly affected by knee flexion angle and anterior tibial load and was the major restraint to anteroposterior (AP) instability in early flexion. No graft currently in use matches the complex anatomy of the normal ACL. Woo et al14 compared anteromedial ACL reconstructions using hamstring and patellar tendon reconstructions versus the native ACL and found significant laxity to a combined rotational load involving internal rotation and valgus tibial torque at 15 and 30 degrees of flexion. This highlights the importance of the posterolateral bundle to knee stability in early knee flexion and has led some to question the anteromedial reconstructions and revisit the idea of anatomical double-bundle reconstructions.

BASIC SCIENCE AND GRAFT HISTOLOGY Evidence from animal experiments lends credence to a “window” of acceptable ACL graft tension. Graft tension that is too high can eventually lead to greater laxity and poorer results than knees fixed under low graft tension. Conversely, other animal studies demonstrate that deliberately de-tensioned grafts lose strength to a greater extent than the normally tensioned ACL. Although a stimulus is essential for the orientation of newly formed collagen during the remodeling phase,15 basic research studying the effect of graft tension cautions that high initial tension may be detrimental to the remodeling process. Yoshiya et al16 found that patellar tendon reconstructions in dogs exposed to high initial graft tension of 39N showed focal degeneration within the graft and replacement of the normal parallel arrangement of collagen fibrils by a myxoid, extracellular matrix. Microangiography demonstrated improved vascularity when the initial tension was 1N rather than 39N. Laxity measurements of the two different preloads showed increased stability of the highly tensioned graft at time zero. However, at 3 months, laxity between the two groups was similar. The use of allograft tissue is gaining popularity in ligament reconstruction. The substantial decrease in graft strength during initial phases of healing in frozen allograft tissue relates to the inflammatory stages associated with revascularization, not the effects of freezing itself.17 Jackson et al18 studied the biomechanical outcomes of devitalized ACL at 0, 6, and 26 weeks after treatment with a freeze probe. At 6 weeks a significant reduction in maximum load to failure was observed. However, at 26 weeks, no differences were noted between frozen and contralateral controls relative to laxity, load to failure, stiffness, or modulus of elasticity. Katsuragi et al19 and Mikami et al20 studied nonphysiologically high initial tension after freezing ACL

Tensioning Anterior Cruciate Ligament Grafts ligaments in dogs. After applying a freeze-thaw treatment to both ACLs, they applied initial tension of 20N to the test group and compared it with the physiologically tensioned contralateral extremity. The tensile strength in the highly tensioned knee decreased significantly at 6 and 12 weeks. Histologically, the collagen fibers in the highly tensioned knees were coarser and disoriented. In the midsubstance of the ACL, the physiological specimens had a spindle-shaped nucleus; however, the highly tensioned ACL had signs of degenerative changes (Fig. 54-2). Overtensioning causes significant degenerative changes in native, autologous BTB, and freeze-thaw–treated ACL. Over time, the mechanical properties of the overtensioned ACL graft deteriorate compared with physiological tension.

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GRAFT-SPECIFIC TENSIONING Stiffness and elasticity vary among autograft tissues. Burks and Leland4 determined that the graft tension needed to restore normal anterior laxity is tissue specific. The material (stiffness) and geometrical (size and length) properties of the graft influence the amount of tension that needs to be applied. In cadaveric knees, they reconstructed the ACL using bone–patellar tendon–bone (BPTB), doubled semitendinosus, or iliotibial band grafts. They tensioned each graft to match translation of an applied 20-pound load (89N) using the KT-1000. The BPTB graft returned the knee to its preoperative condition with a mean of 3.6 pounds (16.2N); doubled semitendinosus graft, 8.5 pounds (38.3N), and iliotibial band graft, 13.6 pounds (61.2N). Due to the characteristics of BTB graft

FIG. 54-2 A, Physiologically tensioned anterior cruciate ligament (ACL) at 6 weeks (magnification
20). B, Highly tensioned ACL at 6 weeks (
20). C, Core sample from a physiologically tensioned ACL at 12 weeks (
100). D, Core sample from a highly tensioned ACL at 12 weeks (
100). E, Midsubstance sample from a physiologically tensioned ACL at 12 weeks (
100). F, Midsubstance sample from a highly tensioned ACL at 12 weeks (
100). (From Katsuragi R, Yasuda K, Tsujino J, et al. The effect of nonphysiologically high initial tension on the mechanical properties of in situ frozen anterior cruciate ligament in a canine model. Am J Sports Med 2000;28:47–56.)

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Anterior Cruciate Ligament Reconstruction superstructure and fixation, they have been generalized as lowtension grafts, whereas the mechanical properties of soft tissue grafts have necessitated high tension for graft fixation. We will review some of the clinical evidence supporting this.

Low-Tension Grafts Fleming et al21 studied the relationship between graft tensioning and AP laxity of the reconstructed goat knee. The AP laxity values of the intact knee were measured with the knee at various flexion angles. The ACL was then severed and the laxity measurements were repeated for nine different tensioning conditions: 30N, 60N, and 90N, each applied with the knee at 30, 60, and 90 degrees of flexion. They concluded that a 60N load applied at 30 degrees was the best combination for restoring normal AP laxity values. Pena et al22 developed a three-dimensional finite element model of the human knee joint. Under an anterior load of 134N, the closest anterior tibial translation to that of the intact knee was obtained with a pretension of 60N. However, they noted that because this load was likely to cause problems in revascularization and remodeling during postoperative healing, an initial tension of 40N was recommended. There is no consensus for the ideal initial tension in BTB graft in clinical studies. Van Kampen et al23 prospectively randomized patients into 20N and 40N load groups and fixed them at 20 degrees of flexion. They found no significant difference in objective or subjective outcomes at 1 year after ACL reconstruction. However, they did note a slight tendency toward progressive instability in the 40N group. Yoshiya et al24 compared initial graft tension in two groups using 25N and 50N fixed at extension. In the immediate postoperative period, the reconstructed knee was similarly overconstrained in both groups. By 3 months, laxity of the surgically treated knee had increased significantly, was similar to the contralateral normal knee, and showed a slight increase between 3 and 6 months. No significant difference in the clinical outcome was observed between the groups at any time during follow-up. Amis and Jakob25 surveyed a number of surgeons in an effort to establish a consensus on graft tensioning. Of those surveyed, the average graft tensioning protocols for BPTB reconstructions were 47N at 11 degrees of knee flexion. As previously mentioned, histological evidence of graft degeneration has been noted in animal models where the native ACL or BTB grafts were tensioned in a range of 20 to 40N. Although there were no direct consequences to knee stability, it reemphasizes the goal of “least amount of tension necessary to restore knee stability.” Applying a 20N load to a low-tension graft should provide adequate stability and reduce the risk of overconstraining the knee and degenerating the graft.

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High-Tension Grafts Multiple outcome studies have indicated that hamstring tendon autografts are associated with higher postoperative laxity measurements than patellar tendon autografts, with clinical instability rates ranging from 10% to 30%.26,27 Instability is defined as a 3-mm side-to-side difference in anterior tibial translation compared with the contralateral intact knee during manual maximum translation. Clinical instability rates ranging from 10% to 30% have been reported following reconstruction with hamstring tendon autografts. Soft tissue grafts present unique challenges. Namely, the length of the tendons are longer, more friction exists within the tunnels, and bone–bone healing is lacking. Considering the properties of soft tissue grafts, most surgeons reconstruct using higher tensions compared with BTB grafts.25 Burks and Leland4 suggested tension two to three times that required in BTB reconstructions to restore normal laxity patterns. Boylan et al28 applied three different loads in a cadaveric model: 68N, 45N, and 23N at 30 degrees of flexion. KT-1000 measurements of anterior translation demonstrated that the 68N load restored stability, whereas the knees loaded with 45N and 23N had significantly more laxity. The clinical evidence offers some clarity to the issue. In a prospective randomized study, Yasuda et al29 followed the clinical results at 2 years in patients who received doubled semitendinosus/gracilis (2xST/Gr) grafts tensioned at 80N, 40N, or 20N. The average side-to-side difference in anterior laxity in the 80N group was significantly less than that in the 20N or 40N group. There were no complications, all patients regained maximum extension, and no difference in subjective outcomes were noted. Kim et al30 randomly allocated 48 patients to three groups in which three different tensions—8 kg (78N), 12 kg (117N), or 15 kg (147N)—were applied to a penta-semitendinosus graft. Postoperatively, the average side-to-side differences in anterior laxity were 1.3, 2.1, and 2.4 mm, respectively, at a minimum of 1 year. There were no significant differences among the groups in subjective clinical results, anterior laxity, or knee extensor strength. As outlined earlier, overcorrecting the joint can lead to deleterious effects on kinematics of the graft and loss of motion. Furthermore, the increase in cartilage compression that occurs with overconstraint and loss of knee motion may lead to a greater degree of degeneration over time. Vachtsevanos et al31 looked at the relationship of soft tissue tensioning and return of postoperative range of motion. They conducted a prospective randomized study using 61 patients reconstructed with autogenous 2xST/Gr. Patients were divided into two groups (15 pounds [68N] and 20 pounds [88N]) and followed in the postoperative period for an average of 15 months. The average side-to-side

Tensioning Anterior Cruciate Ligament Grafts difference in anterior laxity was 1.7  1.5 mm (68N) and 2.8  2.0 mm (88N), which was significant (Fig. 54-3). Additionally, they found a significant delay in regaining extension in the 88N group (Fig. 54-4). Based on the evidence presented, it is reasonable to assume that an initial tension of 70N in soft tissue grafts provides consistent return of motion and clinical stability and that substantially greater tension does not improve results.

FINAL KT-1000 SIDE-TO-SIDE DIFFERENCE 7 Side-to-side difference (mm)

6 5 4 3 2 1 0 5

–1

10

15

20

25

–2 –3 Patients 15 lb. tension 20 lb. tension FIG. 54-3 Side-to-side difference in 15 and 20 pounds of initial tension measured in millimeters with KT-1000 at 20-pound anterior drawer at an average of 15 months’ follow-up. Average side-to-side difference in the 15-pound group was 1.7  1.5 mm; in the 20-pound group, 2.8  2.0 mm (P ¼ 0.047).

12

54

STRESS RELAXATION, PRECONDITIONING, AND PRETENSIONING Due to the viscoelastic characteristic of graft tissue, the initial tension of ACL grafts is finite in nature. Beynnon et al32 reported that initial tension applied to the BTB graft at the time of fixation immediately decreased by creep elongation. Additionally, the percentage of stress relaxation is independent of the peak load applied to the graft.33 The data are similar for soft tissue grafts. Höher et al34 demonstrated a loss of 45% of graft tension in quadrupled hamstring grafts within 30 minutes due to stress relaxation. In vitro studies have been performed to determine the influence of cyclical loading on graft tension following ACL reconstruction. For studies performed with hamstring tendon grafts, bovine extensor tendon grafts, and patellar tendon grafts, cyclical loading reduced graft tension by 50% or more.28,35,36 Numazaki et al37 in a porcine ex vivo study fixed patellar tendon grafts with initial tensions of 20N, 80N, and 140N. A cyclical force–relaxation test was performed for 5000 cycles until the graft was stretched by 2 mm. The average peak load values after cycling were 105N, 157N, and 205N, respectively. Considering the in situ force of the ACL at full extension (16–87N),8 the authors concluded there was no benefit in tensioning the patellar tendon graft greater than 20N. For soft tissue grafts under the same initial loads, the average peak load values after cycling were 27N, 41N, and 39N. Increasing initial tension from 20 to 80N presented a significant increase in peak load after cycling; however, tensioning to 140N did not confer any benefit. Attempts have been made to minimize graft viscoelasticity after reconstruction; pretensioning and preconditioning of the soft tissue grafts before final fixation have been recommended. To review, pretensioning refers to any loading of the graft that is performed before the graft is pulled into the knee (graft preparation board) (Fig. 54-5). Preconditioning refers to

Time in weeks

10 8 6 4 2 0 90

120

Range of motion (degrees) 15 lbs. tension 20 lbs. tension FIG. 54-4 Time to achieve 90 and 120 degrees of flexion for 15- and 20-pound groups (P ¼ 0.018).

FIG. 54-5 Example of pretensioning doubled semitendinosus/gracilis graft using Acufex Graftmaster board.

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Anterior Cruciate Ligament Reconstruction loading of the graft that is performed once the graft has been fixed in one of the tunnels (usually the femoral tunnel). Preconditioning may be further divided into cyclical and isometric preconditioning. The former denotes a load applied in multiple consecutive bouts (cycles), and the latter denotes a constant load applied on the graft before the final fixation of the graft. Despite the common use of pretensioning in graft preparation, there is little clinical evidence to support its effectiveness. Howard et al38 noted a 10% increase in length of patellar tendon grafts after applying an 89N load for 15 minutes. They concluded that without pretensioning, significant postimplantation graft creep will occur. Several pretensioning techniques have been developed for soft tissue grafts. Tension of 15 to 20 pounds (44–88N) for 10 to 20 minutes has been suggested for pretensioning hamstring tendon grafts. The initially set tension gradually decreases over time as the graft is stretched and the sutures are tightened around the tendon bundle. Accordingly, it would be misleading to claim that the graft was tensioned with a constant load during the entire time. However, it is reasonable to assume that pretensioning does eliminate some creep within the suture–graft interface and allow the surgeon to provide a more consistent initial tension, and it certainly improves the ease of graft preparation. There is no obvious utility in pretensioning BTB grafts. More sophisticated studies looking at the effectiveness of preconditioning over time are inconclusive. Nurmi et al39 tested the effectiveness of preconditioning by assigning anterior tibialis grafts to three groups: control, cyclical preconditioned, and isometric preconditioned. The residual graft tension was then recorded immediately after the application of an initial graft tension of 80N and fixation into tibia with an interference screw. Immediately after screw insertion, the residual (AT) graft tensions were 79N  19N, 100N  17N, and 102N  15N, respectively. However, after 1 hour, a 60% decrease occurred in the initially set tension. Ejerhed et al40 prospectively randomized 53 patients undergoing patellar tendon autograft into two groups. One group of patients underwent isometric preconditioning by passive stretching at a constant load of 39N for 10 minutes immediately prior to implantation. The other group underwent no preconditioning before the implantation of the graft. At an average of 25 months, no significant objective or subjective differences were noted. To date, there is no clinical evidence proving that pretensioning or preconditioning of grafts will overcome the viscoelastic nature of graft tissue and improve clinical outcomes. However, cyclical preconditioning does allow the surgeon to identify the force–flexion curve of a specific graft before final fixation.

404

KNEE FIXATION ANGLE When considering the ideal knee flexion angle at fixation, certain assumptions must be made. Namely, the femoral and tibial tunnels are placed near the native ACL origin and insertion. Excessively anterior placement of the femoral tunnel causes significant increases in ACL tension in flexion and laxity near extension. We know from kinematic studies that the forces generated in the graft as well as in the intact ACL are greatest at full extension and minimal between 30 and 60 degrees of knee flexion.41 Cadaveric studies by Bylski-Austrow et al5 concluded that a greater increase in force (50–115N) and greater posterior shifts in tibial position were produced by changing the flexion angle at tensioning from 0 to 30 degrees, rather than doubling the initial tension from 20 to 40N (15–35N). Gertel et al42 measured ACL graft force using BTB in cadaveric knees and concluded that graft forces are greater when the initial tension was applied at 30 degrees of flexion rather than at 0 degrees. This has led most surgeons to fix their grafts between 10 and 30 degrees of flexion.25 Asahina et al43 conducted one of the few clinical studies examining the importance of knee flexion angle at graft fixation. Using the modified Macintosh technique, 19 patients were fixed with the knees at full extension, whereas 25 patients were fixed at 30 degrees of flexion. A 70N force measured with a spring balance was used for both groups. At an average of 38 months, the range of motion in the extension group was significantly better. However, the stability of the knees and arthroscopic appearance of the grafts were significantly worse. This led the authors to suggest that graft fixation at 30 degrees of flexion is more effective in restoring stability and sustaining graft viability. Ultimately, there is no set number for the ideal knee flexion angle at graft fixation that can be effective in every reconstruction. Clearly, fixation in the arc of 10 to 30 degrees imparts a significant force to the ACL graft, and fixation at greater than 60 degrees can create difficulty in regaining maximal extension postoperatively. The surgeon must look at the behavior of the graft during cyclical preconditioning to determine the ideal knee flexion angle for fixation, which will be discussed in the following section.

TENSIONING DEVICES AND STRATEGIES As mentioned previously, every graft produces its own individual force–flexion curve based primarily on the position of tunnel placement. After the graft is fixed in the femoral tunnel, the knee should be taken through a range of motion with tension on the tibial end of the graft (cyclical preconditioning). Based on graft length changes, which are assessed

Tensioning Anterior Cruciate Ligament Grafts by motion of the graft within the tunnel, the point where the graft will be slack and where graft tension increases should be identified. Ideally, an isometric placed graft will show no significant motion and could be tensioned at any point in the flexion arc.44 Clinically, 2 to 3 mm of elongation is acceptable as long as the pattern of deviation throughout the range of motion reproduces that of the native ACL. Namely, in well-placed tunnels, this inflexion point occurs near extension as the graft begins to shorten in the tunnel. Cunningham et al45 studied the results of 13 orthopaedic sports medicine physicians who were asked to tension a soft tissue graft as they would in surgery and then maximally. They found that graft tensioning was highly variable and questioned whether tension should be more accurately measured and controlled intraoperatively. Commercially available ACL tensioning devices can be applied to the tibial end of the graft (Figs. 54-6 and 54-7). These allow

54

the surgeon to dial in the set amount of tension, eliminating the need for an assistant. To date, no clinical studies have identified more consistent or improved outcomes using these devices. Although an obvious controversy exists concerning the ideal pretensioning, preconditioning, and initial tensioning of ACL grafts, consensus does prevail. In low-tension grafts (BTB), pretensioning imparts little benefit and the graft should be fixed in the range of 20N. For high-tension grafts (semitendinosus), pretensioning may improve the immediate viscoelastic behavior of the graft and the graft should be fixed at no greater than 80N. Preconditioning of both graft types is advised to characterize the inflexion point of the individual graft before final fixation. With well-placed tunnels, this point should be near full extension (10–30 degrees), at which time the desired initial tension can be set.

References

FIG. 54-6 Example of a preconditioning device (prototype).

FIG. 54-7 Example of another preconditioning device: the Tie Tensioner (DePuy-Mitek, Johnson & Johnson Gateway).

1. Jones KG. Reconstruction of the anterior cruciate ligament: a technique using the central one-third of the patellar ligament. J Bone Joint Surg 1963;45A:925–932. 2. Melby A III, Noble JS, Askew MJ, et al. The effects of graft tensioning on the laxity and kinematics of the anterior cruciate ligament reconstructed knee. Arthroscopy 1991;7:257–266. 3. Fleming B, Beynnon B, Howe J, et al. Effect of tension and placement of a prosthetic anterior cruciate ligament on the anteroposterior laxity of the knee. J Orthop Res 1992;10:177–186. 4. Burks RT, Leland R. Determination of graft tension before fixation in anterior cruciate ligament reconstruction. Arthroscopy 1988;4:260–266. 5. Bylski-Austrow DI, Grood ES, Hefzy MS, et al. Anterior cruciate ligament replacements: a mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension. J Orthop Res 1990;8:522–531. 6. Lewis JL, Lew WD, Hill JA, et al. Knee joint motion and ligament forces before and after ACL reconstruction. J Biomech Eng 1989;111:97–106. 7. Andersen HN, Jorgensen U. The immediate postoperative kinematic state after anterior cruciate ligament reconstruction with increasing preoperative tension. Knee Surg Sports Traumatol Arthrosc 1998;6: S62–S69. 8. Markolf KL, Gorek JF, Kabo JM, et al. Direct measurement of resultant forces in the anterior cruciate ligament. An in vitro study performed with a new experimental technique. J Bone Joint Surg 1990;72A:557–567. 9. Wascher DC, Markolf KL, Shapiro MS, et al. Direct in vitro measurement of forces in the cruciate ligaments. Part I: the effect of multiplane loading in the intact knee. J Bone Joint Surg 1993;75A:377–386. 10. Paulos L, Noyes FR, Grood E, et al. Knee rehabilitation after anterior cruciate ligament reconstruction and repair. Am J Sports Med 1981;9:140–149. 11. Arms SW, Pope MH, Johnson RJ, et al. The biomechanics of anterior cruciate ligament rehabilitation and reconstruction. Am J Sports Med 1984;12:8–18. 12. Beynnon BD, Johnson RJ, Fleming BC, et al. The strain behavior of the anterior cruciate ligament during squatting and active flexionextension. A comparison of an open and a closed kinetic chain exercise. Am J Sports Med 1997;25:823–829. 13. Sakane M, Fox RJ, Woo SL, et al. In situ forces in the anterior cruciate ligament and its bundles in response to anterior tibial loads. J Orthop Res 1997;15:285–293.

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Anterior Cruciate Ligament Reconstruction 14. Woo SL, Kanamori A, Zeminski J, et al. The effectiveness of reconstruction of the anterior cruciate ligament with hamstrings and patellar tendon. A cadaveric study comparing anterior tibial and rotational loads. J Bone Joint Surg 2002;84A:907–914. 15. Frank C, Amiel D, Akeson WH. Healing of the medial collateral ligament of the knee. A morphological and biochemical assessment in rabbits. Acta Orthop Scand 1983;54:917–923. 16. Yoshiya S, Andrish JT, Manley MT, et al. Graft tension in anterior cruciate ligament reconstruction. An in vivo study in dogs. Am J Sports Med 1987;15:464–470. 17. Jackson DW, Grood ES, Wilcox P, et al. The effects of processing techniques on the mechanical properties of bone-anterior cruciate ligament-bone allografts. An experimental study in goats. Am J Sports Med 1988;16:101–105. 18. Jackson DW, Grood ES, Cohn BT, et al. The effects of in situ freezing on the anterior cruciate ligament. An experimental study in goats. J Bone Joint Surg 1991;73A:201–213. 19. Katsuragi R, Yasuda K, Tsujino J, et al. The effect of nonphysiologically high initial tension on the mechanical properties of in situ frozen anterior cruciate ligament in a canine model. Am J Sports Med 2000;28:47–56. 20. Mikami S, Yasuda K, Katsuragi R, et al. Reduction of initial tension in the in situ frozen anterior cruciate ligament. Clin Orthop Relat Res 2004;9:207–213. 21. Fleming BC, Abate JA, Peura GD, et al. The relationship between graft tensioning and the anterior-posterior laxity in the anterior cruciate ligament reconstructed goat knee. J Orthop Res 2001;19:841–844. 22. Pena E, Martinez MA, Calvo B, et al. A finite element simulation of the effect of graft stiffness and graft tensioning in ACL reconstruction. Clin Biomech (Bristol, Avon) 2005;20:636–644. 23. van Kampen A, Wymenga AB, van der Heide HJ, et al. The effect of different graft tensioning in anterior cruciate ligament reconstruction: a prospective randomized study. Arthroscopy 1998;14:845–850. 24. Yoshiya S, Kurosaka M, Ouchi K, et al. Graft tension and knee stability after anterior cruciate ligament reconstruction. Clin Orthop Relat Res 2002;394:154–160. 25. Amis AA, Jakob RP. Anterior cruciate ligament graft positioning, tensioning and twisting. Knee Surg Sports Traumatol Arthrosc 1998; 6:S2–S12. 26. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 27. Freedman KB, D’Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 28. Boylan D, Greis PE, West JR, et al. Effects of initial graft tension on knee stability after anterior cruciate ligament reconstruction using hamstring tendons: a cadaver study. Arthroscopy 2003;19:700–705. 29. Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Autogenous doubled hamstring tendons connected in series with polyester tapes. Am J Sports Med 1997;25:99–106.

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30. Kim SG, Kurosawa H, Sakuraba K, et al. The effect of initial graft tension on postoperative clinical outcome in anterior cruciate ligament reconstruction with semitendinosus tendon. Arch Orthop Trauma Surg 2006;126:260–264. 31. Vachtsevanos JG, Lamberson KA, Paulos LE. Anterior cruciate graft tensioning. Tech Knee Surg 2003;21:125–136. 32. Beynnon BD, Johnson RJ, Fleming BC, et al. The measurement of elongation of anterior cruciate-ligament grafts in vivo. J Bone Joint Surg 1994;76A:520–531. 33. Johnson GA, Tramaglini DM, Levine RE, et al. Tensile and viscoelastic properties of human patellar tendon. J Orthop Res 1994;12:796–803. 34. Höher J, Scheffler SU, Withrow JD, et al. Mechanical behavior of two hamstring graft constructs for reconstruction of the anterior cruciate ligament. J Orthop Res 2000;18:456–461. 35. Arnold MP, Lie DT, Verdonschot N, et al. The remains of anterior cruciate ligament graft tension after cyclic knee motion. Am J Sports Med 2005;33:536–542. 36. Grover DM, Howell SM, Hull ML. Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices. J Bone Joint Surg 2005;87A:381–390. 37. Numazaki H, Tohyama H, Nakano H, et al. The effect of initial graft tension in anterior cruciate ligament reconstruction on the mechanical behaviors of the femur-graft-tibia complex during cyclic loading. Am J Sports Med 2002;30:800–805. 38. Howard ME, Cawley PW, Losse GM, et al. Bone-patellar tendonbone grafts for anterior cruciate ligament reconstruction: the effects of graft pretensioning. Arthroscopy 1996;12:287–292. 39. Nurmi JT, Kannus P, Sievanen H, et al. Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction: part 2: effect of preconditioning on graft tension during and after screw insertion. Am J Sports Med 2004;32:418–424. 40. Ejerhed L, Kartus J, Kohler K, et al. Preconditioning patellar tendon autografts in arthroscopic anterior cruciate ligament reconstruction: a prospective randomized study. Knee Surg Sports Traumatol Arthrosc 2001;9:6–11. 41. Fleming B, Beynnon BD, Johnson RJ, et al. Isometric versus tension measurements. A comparison for the reconstruction of the anterior cruciate ligament. Am J Sports Med 1993;21:82–88. 42. Gertel TH, Lew WD, Lewis JL, et al. Effect of anterior cruciate ligament graft tensioning direction, magnitude, and flexion angle on knee biomechanics. Am J Sports Med 1993;21:572–581. 43. Asahina S, Muneta T, Ishibashi T, et al. Effects of knee flexion angle at graft fixation on the outcome of anterior cruciate ligament reconstruction. Arthroscopy 1996;12:70–75. 44. Arnold MP, Verdonschot N, van Kampen A. The normal anterior cruciate ligament as a model for tensioning strategies in anterior cruciate ligament grafts. Am J Sports Med 2005;33:277–283. 45. Cunningham R, West JR, Greis PE, et al. A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament. Arthroscopy 2002;18:983–988.

PART K LIGAMENTIZATION AND GRAFT-TUNNEL HEALING

Graft Remodeling and Ligamentization After Anterior Cruciate Ligament Reconstruction The successful reconstruction of ligamentous structures in the knee joint, such as the anterior cruciate ligament (ACL), requires understanding several factors. These are the mechanical properties of the selected graft tissue as well as the mechanical behavior and fixation strength of its fixation materials. However, it is more important to understand the biological processes that occur during graft remodeling, maturation, and incorporation because they affect the mechanical properties of the ACL reconstructed knee joint and therefore determine the rehabilitation and time course until normal function of the knee joint can be expected. Several studies have analyzed the various changes that occur during graft healing.1–24 Two main sites of healing exist, which should be separately assessed because their biological processes vary substantially: the intraarticular graft remodeling, often referred to as ligamentization, and the intratunnel graft incorporation, which develops either by bone–bone or tendon– bone healing. In the beginning of the 20th century, Wilhelm Roux described the “law of functional adaptation,” elucidating on the fact that “an organ will adapt itself structurally to an alteration, quantitative or qualitative in function,”25 laying groundwork for later research on ligamentization. He observed that soft tissue structures such as ligaments and tendons undergo specific changes in their mechanical and biological properties when they are exposed to a different mechanical loading and biological environment. Amiel et al were among the first authors1,26 to

analyze the specific functional adaptation of an ACL replacement graft and postulate the term ligamentization. They found a continuous development of a patellar tendon graft with biological and mechanical properties different from the ACL into a structure that closely resembled these properties of the intact ACL. They showed that the patellar tendon underwent several phases of remodeling: an early phase with central graft necrosis and hypocellularity and no detectable revascularization of the graft tissue. This was followed by a phase of proliferation—the time of most intensive remodeling and revascularization—and finally a ligamentization phase that provided characteristic restructuring of the graft toward the properties of the intact ACL. Amiel described this process as a transformation, not a restoration, of the native ACL because characteristic differences remained compared with its replacement grafts. This study laid the foundation for increased research efforts to improve the understanding of the basic science of intraarticular ACL graft healing or ligamentization. With the evolution of ACL reconstruction techniques to graft fixation in bone tunnels, it was not until the beginning of the past decade that the first studies were published on the biological processes during osseous graft incorporation.* It was recognized that the combined healing of the intraarticular remodeling and the intraosseous graft incorporation was dictating the mechanical function of the joint after ACL reconstruction.

55 CHAPTER

Sven Ulrich Scheffler Frank Norman Unterhauser Andreas Weiler

*References 4, 12, 15, 21, 27–29.

407

Anterior Cruciate Ligament Reconstruction This chapter will summarize the current knowledge of the temporal and spatial changes of the intraarticular graft healing and relate them to the mechanical properties of the ACL graft tissue. Differences between basic science in vitro and in vivo animal studies and human biopsy studies will be explained, and the importance of adequate postoperative care following ACL reconstruction will be highlighted.

EARLY GRAFT-HEALING PHASE The early graft healing phase extends from the time of ACL reconstruction until around the fourth postoperative week. In comparison to studies of the subsequent proliferation and ligamentization phases, significantly less studies exist with analyses of the biological events of this early graft healing phase. Most authors agree, using different in vivo animal models,1,2,18,30,31 that this time period is marked by increasing graft necrosis, mainly in its center, and hypocellularity. Ultrastructural cell changes such as mitochondrial swelling, dilatation of the endoplasmatic retinaculum, and intracytoplasmatic deposition of lipids, as well as macroscopic swelling and increased cross-sectional area, illustrate the increasing graft necrosis and degradation.30 During this time, no graft revascularization can be observed.2,9,32,33 The graft necrosis leads to a release of a number of cytokines, such as tumor necrosis factor (TNF)–a, interleukin (IL)–1ß, and IL-6, in addition to chemokines that trigger a cascade of growth factors expression, which in turn result in cell migration and proliferation as well as extracellular matrix synthesis and revascularization.11,34 This remodeling activity becomes more pronounced during the latter proliferative phase. However, already between the first and second weeks, an influx of cells can be seen into the graft’s periphery.30,31 Kleiner et al9 and later Yoshikawa et al33 were able to demonstrate that these cells were originating from tissue other than the graft itself and that all original graft cells were completely replaced by 2 to 4 weeks. They hypothesized that the source of cells was either the synovial fluid, cells from the stump of the native ACL, or bone marrow elements originating from drilling maneuvers. Therefore Arnoczky2 suggested that preservation of the ACL stump and the Hoffa fat pad might be beneficial, especially for the early healing period. During the first postoperative weeks, the graft’s overall collagen structure and its crimp pattern are still maintained,1 even though the beginning disintegration of the collagen fibrils and their orientation can be observed as early as 3 weeks after reconstruction.30,35 This explains the slow decrease in the mechanical properties of the graft at this early healing phase.4,15,20 408

Very little is known about the healing processes in the osseous tunnels, which will be described in more detail in the following chapter of this book. In summary, only little graft incorporation can be seen during this early stage of healing, such that the mechanical properties of the freshly ACL reconstructed knee joint are primarily relying on the mechanical fixation of the graft. Biomechanical testing of intraarticular ACL reconstructions between 2 and 4 weeks4,5,13,20 shows consistent failure by graft pullout from the tunnel, indicating insufficient anchorage of the graft to the tunnel wall. The mechanical strength of the ACL reconstruction at this time is significantly lower than that at the time of implantation. However, it continues to decrease until around 6 weeks, when a further increase in graft remodeling activity can be found and the failure site shifts to the intraarticular graft region.4,15,20 The decrease in mechanical strength might lead to the conclusion that early graft loading (i.e., immediate loading of the freshly reconstructed knee joint) should be avoided. However, several studies have pointed out the importance of adequate mechanical loading for the healing graft. Ohno et al36 stress-deprived the patellar tendon in vivo and found a significant loss of tensile strength as early as 1 week with further deterioration until 6 weeks of healing. This loss in tensile strength was accompanied by splitting and defragmentation of collagen bundles as early as 2 weeks. Similar findings were reported by Majima et al,37 who examined differences in complete and partial stress-shielding of a soft tissue graft, detecting a significantly higher loss in tensile strength from the first to third week of healing for the complete stress-shielded group. In another study38 the authors explained this observation with ultrastructural changes in the collagen composition that shifted to small-diameter fibrils, which were shown to provide less mechanical strength than the large-diameter fibrils found in the intact ACL.39,40 However, overloading of the graft can also lead to impaired graft healing. Tohyama and Yasuda showed in their model using an in situ frozen patellar tendon that a reduction of the cross-sectional area of the tendon by half (thereby doubling the tendon stress during loading) resulted in substantially reduced tensile strength as early as 3 weeks, contrary to only a slight increase in tendon stress (when the cross-sectional area was reduced by only onethird), which did not significantly impair the mechanical strength.41 All these studies show that ACL graft healing can only progress if mechanical loading occurs; however, the adequate magnitude must be determined. At this early time of healing, anterior knee stability mainly depends on good graft fixation because graft incorporation by tendon–bone healing has not yet occurred. Adequate fixation strength also allows for mechanical loading of the healing graft, which is

Graft Remodeling and Ligamentization After Anterior Cruciate Ligament Reconstruction required for good graft maturation, as previously discussed. However, excessive loading must be also avoided because of the decreasing mechanical strength of the intraarticular graft structure during the first postoperative month. No human biopsy studies exist for the initial early healing period. Therefore the current knowledge is solely based on in vitro cell analyses (human and animal) and in vivo animal models. All animal models have certain limitations, such as the difficulty to precisely control postoperative weight bearing. Also, limitations exist in the replication of today’s refined techniques with optimized graft placement and strong fixation, which might have an important impact on the mechanical forces that are transmitted to the graft and its ensuing early remodeling and healing.

PROLIFERATION PHASE OF GRAFT HEALING The proliferation phase is characterized by a maximum of cellular activity and changes of the extracellular matrix, which are paralleled by the lowest mechanical properties of the ACL reconstruction during healing. Because cellular proliferation has already begun during the early healing period, there is a continuous transition between these two phases. However, with the most characteristic changes occurring between the fourth and twelfth postoperative week, this phase is referred to as the proliferation phase of ACL graft healing. During this phase, cellularity constantly increases and substantially surpasses that of the intact ACL, as was observed in various in vivo animal models.3,8,18,20,42 Cell clusters are found at the perimeter of the graft around 6 weeks, with large acellular areas remaining in the graft’s center (Fig. 55-1). These hypercellular regions were shown to consist of mesenchymal stem cells18 and activated fibroblasts11 that are actively secreting several growth factors such as basic fibroblast growth factor (bFGF), TGF-ß1, and isoforms of plateletderived growth factor (PDGF) to initiate and maintain graft remodeling. Kuroda et al11 found that the release of these growth factors peaks between the third and sixth week and almost completely ceases at 12 weeks of healing, which lends further explanation for the maximum remodeling activity during this proliferation phase. A more even distribution of cells throughout the graft slowly develops thereafter. Cell numbers are still increased but recede toward the intact ACL cellularity at the end of the proliferation phase.17,20 An increased number of specific fibroblasts, so-called myofibroblasts, are also found during this healing phase.43,44 These fibroblasts have the ability to exert isometric tension on the surrounding cellular and extracellular matrix. In the intact ACL they seem to be responsible for the crimping structure of the collagen fibers.45 These contractile fibroblasts are progressively expressed during the first three postoperative

55

months17,44 in the healing ACL graft, when they seem to be responsible for the restoration of the in situ tension that is required for the later ligamentization process. At the same time of increased cellular proliferation and intense revascularization of the graft tissue, Yoshikawa et al24 found upregulated expression of vascular endothelial growth factor (VEGF), a potent stimulator of angiogenesis, already at 2 to 3 weeks postreconstruction, which is triggered by hypoxia during the avascular necrosis of the early healing phase (Fig. 55-2).47 However, they did not find a significant increase in vascular outgrowth before the fourth and eighth week, confirming the descriptive findings of other previously published studies. Petersen et al14 and Unterhauser et al42 independently showed that revascularization progresses from the periphery of the graft toward the entire graft diameter at the end of the proliferation phase around 12 weeks of healing (see Fig. 55-2). Vascular density then returns to values of the intact ACL during the phase of ligamentization by 6 months.14,42 It is assumed that this intense revascularization triggers and retains the maximal remodeling activity. It has been a matter of debate whether such increased revascularization is beneficial to the healing of the graft. Recent studies found that upregulation of revascularization (e.g., by exogenous application of VEGF) enhanced cellular infiltration and fibroblast expression during the proliferation phase of healing, but this also included a significant deterioration of the graft’s mechanical properties.33 Weiler et al were able to relate the vascularity of the healing ACL graft in sheep to its mechanical properties using gadolinium-enhanced magnetic resonance imaging (MRI).23 They found that the time of maximal revascularization coincides with the lowest mechanical properties of the healing graft tissue, which was seen around 6 weeks. Tohyama and Yasuda were able to show that increased remodeling activity in terms of extracellular infiltration and revascularization was directly related to the decline in the graft’s mechanical properties.19 These findings support the reports of numerous other studies that all found the mechanical properties to be at their minimum around the proliferation phase of healing at 6 to 8 weeks.* Graft failure at this time point occurs either by midsubstance tear20 or graft pullout due to stripping of the graft tissue out of its bone tunnels.3,13 This illustrates that the graft tissue has become the weak link in the reconstruction compared with the graft–bone interface (due to the lack of graft incorporation) during the early healing phase. Another factor that has been identified to play a role in the reduced mechanical properties is the loss of regular collagen orientation and crimp pattern, which has progressed since the early healing phase. It is not until the ligamentization phase that a slow restoration of the collagen orientation and crimp pattern progresses1,8,17,20 *References 3–5, 8, 13, 15, 17, 18, 20, 22, 27, 29.

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FIG. 55-1 Anterior cruciate ligament (ACL) graft at 6 weeks of healing (Masson-Goldner trichrome staining). A, Graft hypercellularity (400) with (B) cellular invasion into the periphery and remaining acellular areas of the graft (100) and (C) hypervascularity at the areas of increased cellular density (100, immunohistochemistry, Faktor VIII).

FIG. 55-2 Revascularization during graft healing.17 A, Intact anterior cruciate ligament (ACL); B, 6 weeks; C, 12 weeks. D, 52 weeks.

410

Graft Remodeling and Ligamentization After Anterior Cruciate Ligament Reconstruction (Fig. 55-3). At the beginning of the proliferation phase, a significant decrease in collagen fibril density is demonstrated, which is followed by increased collagen synthesis48 and a subsequent return to values of the intact ACL at 12 weeks, as shown in an electron microscopy study by Weiler et al.20 During this time of new collagen formation, a shift can be observed from large-diameter collagen fibrils, which are dominant in the intact ACL or patellar or hamstring tendon graft, to small-diameter fibrils.9,20,49,50 It has been hypothesized that this shift in collagen diameter and the increased expression of collagen type III in the healing graft51 might explain why a full restoration of the mechanical strength of the intact ACL has not been observed even after 2 years of healing. Although a substantial deterioration of the mechanical properties of the healing graft during the proliferation phase

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has been reported in animal models, clinical outcomes after ACL reconstruction with immediate aggressive rehabilitation have been more successful. Several human biopsy studies found significant differences between the remodeling activity of human ACL grafts during the first 3 months and the healing graft in animal models. Although the previously described healing phases of animal models (graft necrosis, recellularization, revascularization) are also found in human ACL graft biopsies,16,52 the remodeling activity of human ACL grafts seems to be reduced. The complete replacement of all intrinsic graft cells by extrinsic cells, as in animal models, has not been shown in the human healing ACL graft.16,52 Rougraff and Shelbourne16 found viable intrinsic graft cells in human biopsy specimens at all time points between 3 and 8 weeks after ACL reconstruction. Also, the excessive graft necrosis observed in animal studies could not

FIG. 55-3 Change in collagen crimp during graft healing (polarized light microscopy 200; sheep model17,44). A, Intact anterior cruciate ligament (ACL); B, flexor tendon graft; C, 6 weeks; D, 12 weeks; E, 24 weeks; F, 52 weeks.

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Anterior Cruciate Ligament Reconstruction be found in humans, in whom necrosis or degeneration never involved more than 30% of the graft’s biopsies. Large areas of the human ACL graft seem to stay unchanged, displaying tendinous structure with normal collagen alignment and crimp pattern.52 These areas were histologically identical to the native patellar tendon, suggesting survival of portions of the original graft. Neovascularization was also found but did not seem to be as excessive as in the animal model.52 Loss of collagen organization was only detected in areas of neovascularization in human biopsies, which corresponds with the findings in animal models. These findings might explain why early loading and aggressive rehabilitation during the first 3 postoperative months after human ACL reconstruction did not result in a significant increase in failure rates. However, human biopsy studies confirm the remodeling cascade of (limited) graft necrosis, recellularization, revascularization, and changes in collagen crimp and composition during the early healing and proliferation phases, also suggesting that the human ACL graft might have its lowest mechanical strength around 6 to 8 weeks postoperatively. The most appropriate loading for optimization of this phase of graft healing will have to be determined. It must be high enough to stimulate graft cells to produce cellular and extracellular components for preservation of graft stability without compromising graft integrity, which might result in early stretch-out of the ACL reconstruction.

LIGAMENTIZATION PHASE OF GRAFT HEALING The ligamentization phase follows directly after the proliferation phase and involves the ongoing process of continuous remodeling of the ACL graft toward the morphology and mechanical strength of the intact ACL. A clear endpoint of this phase cannot be defined because certain changes still occur even years after ACL reconstruction. It is still a matter of debate whether a full restoration of the biological and mechanical properties of the intact ACL is possible or whether it is more of a transformation of graft tissue that resembles but not does not fully replicate the properties of the intact ACL. It has been shown in animal studies that cellularity slowly returns to values of the intact ACL between 3 and 6 months after reconstruction.17,23,42,46 The typical ovoid shape of metabolically active fibroblasts with its increased cytoplasm/nucleus ratio of the proliferation phase slowly changes into the less metabolically active shape of linear, spindle-like fusiform cells that are normally seen in the intact ACL. Vascularity throughout the graft decreases and returns to values of the intact ACL, and vessels become evenly distributed throughout the entire graft between 6 and 12 months2,17,23,24,42,46 (see Fig. 55-3). It has also been shown in rabbit, dog, and sheep models1,21,23,53 412

for certain extracellular matrix proteins such as glycosaminoglycans and collagen cross-links that the healing graft undergoes a transformation from its initial tissue properties (e.g., a patellar tendon of free soft tissue tendon graft) to properties of the intact ACL during this ligamentization phase1,53 as early as 6 months. Although certain biological features of the healing graft have been reported to return to the morphology of the intact ACL, several differences remain, especially regarding the extracellular matrix. Collagen fibers regain their organization into fascicles after complete loss of alignment and initial dense packaging during the ligamentization phase, which microscopically resembles the appearance of the intact ACL around 6 to 12 months after reconstruction.17,44 However, their initial loss in collagen crimp and strict parallel alignment during the proliferation phase is only partially restored. A regular crimp of the collagen fibers can be seen as early as 6 months, but even after 2 years its frequency stays increased compared with the intact ACL, as shown in sheep.17,44 The change from a bimodal distribution of small and dominating large collagen fibers of the patellar or hamstring tendon graft to a unimodal pattern of only small collagen fibers of the healing graft does not change during the phase of ligamentization8,20,28 (Fig. 55-4). The heterogenous composition of collagen fibers of varying diameter of the intact ACL is never restored.54 The increased synthesis of collagen type III of the proliferation phase decreases during the ligamentization phase but continues to be sustained in significantly higher concentrations than in the intact ACL even at 2 years.30,55 Ng et al found in a dog model of ACL reconstruction that type III collagen also remained increased in the remodeling graft at 1 year but returned to values of the intact ACL by 3 years, suggesting that the ligamentization process might continue longer than previously expected.53 Type III collagen is normally found in scar or early ligamentous repair tissue and has a lower mechanical strength than type I collagen. The findings of persistent small-diameter collagen fibrils and increased type III collagen content are therefore especially important to understand why all animal models demonstrated significantly lower mechanical properties of the healing graft than that of the intact ACL even after long-term healing of up to 2 years.* It has been shown that the mechanical properties of ACL reconstructed knee joints improve substantially during the phase of ligamentization and reach their final maximal properties at around 1 year. But until now there has not been a single animal study demonstrating that the structural properties (e.g., failure load, stiffness) of the healing graft could surpass 50% to 60% of the intact ACL.{ Some studies were able to show that these compromised mechanical properties would still allow for restoration of anteroposterior (AP) laxity to the laxity of the contralateral intact ACL,22 but others observed significant *References 4, 8, 17, 22, 23, 30, 53. {References 3, 4, 8, 13, 17, 22, 23, 27, 46, 53, 56.

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FIG. 55-4 Collagen remodeling of a sheep anterior cruciate ligament (ACL) graft. Continuous shift from the bimodal collagen diameter distribution of the initial soft tissue graft (sheep long flexor tendon) to a unimodal, small-diameter collagen fibril distribution at 52 weeks and comparison with the heterogenous collagen fibril diameter of the intact ACL. A, Intact ACL; B, flexor tendon graft; C, 12 weeks; D, 52 weeks.

lower AP laxity even 3 years after reconstruction.56 In summary, in animal models overall restoration of graft integrity and histological appearance is completed between 6 and 12 months of healing, acquiring morphology similar to that of the intact ACL. This is also substantiated by the mechanical properties that reach their maximal strength around 12 months without any further significant changes thereafter. However, characteristic differences, especially in extracellular matrix composition, remain, and the initial mechanical strength of the intact ACL is not restored. Although human biopsy studies showed substantial differences from animal models for the proliferation phase, the ligamentization phase seems to be rather similar in both models in terms of biological progression. However, the timeline of these biological changes appears to be different in human versus animal models. Rougraff et al57 analyzed 23 biopsies of human patellar tendon ACL reconstruction between 3 weeks and 6.5 years postoperatively. They found that necrosis took place in much smaller areas of the graft at 3- and 6-week biopsies than was shown in animal models. However, they found overall degeneration (albeit limited compared with animal models) to increase until 6 to 10 months and only slowly disappear between 1 and 3 years postoperatively. Neovascularity and hypercellularity only slowly appeared and carried on until 10 months, which differs from observations in animal models. Some nonbiopsy

studies that evaluated graft revascularization using gadolinium-enhanced MRI during the course of healing for 2 years6 could not detect any revascularization except from the periligamentous ACL graft tissue, which is in contrast to the findings of Weiler et al,23 who analyzed sheep ACL reconstruction (also using gadolinium-enhanced MRI) and could detect significantly upregulated neovascularization during the first 3 postoperative months. This underlines the differences in remodeling activity between humans and animal models, even though all human biopsy studies have shown that neovascularization does occur but that the extent of vascularity might be below the threshold detectable with gadolinium-enhanced MRI. Overall, Rougraff et al57 concluded that the proliferation phase seemed to be delayed compared with animal models, with the highest remodeling activity occurring between 3 and 10 months. Identical findings were made by Falconiero et al58 using patellar tendon and hamstring tendon ACL reconstruction. They found that hypercellularity and hypervascularity had not returned to control intact ACL values before 6 to 12 months, with fiber alignment being restored around 6 months. No details are given on ultrastructural differences between the healing graft and the intact ACL in this study. Full histological maturity was not found prior to 12 months of healing. Other studies54,57 even found increased cell counts and differing fiber alignment beyond 3 years, with graft being indistinguishable 413

Anterior Cruciate Ligament Reconstruction from the intact ACL as late as 3-year biopsies. Human biopsy studies that analyzed changes of the extracellular matrix observed changes that are in line with the findings of animal models. Marumo et al59 found that the collagen cross-links (dihydroxylysinonorleucine/hydroxylysinonorleucine ratios) of patellar tendon and hamstring tendon autografts had changed from time zero, when they were significantly different from the intact ACL, to 1 year postoperatively, when both grafts had acquired cross-link ratios that were identical to the intact ACL, confirming the ligamentization process found in animal models. Interestingly, biopsy specimens taken at 6 months still showed significantly different cross-link ratios of the healing grafts compared with the intact ACL, which is different from the earlier cross-link restoration found in animal models. This also confirms the differing timeline of the remodeling of human ACL grafts. Regarding collagen remodeling, Cho et al60 and Abe et al54 confirmed the findings of Weiler et al20 and others8,28 that patellar tendon54 and hamstring tendon60 ACL grafts showed a replacement of largediameter fibrils by small-diameter fibrils, which did not change even after more than 2 years after reconstruction, confirming the observations made in animal models. It is important to understand that the results of graft healing studies in animal models cannot be directly applied to the human ACL patient. The biological processes are similar, but the intensity of graft remodeling in humans is significantly lower than in animal models. Graft integrity is much less compromised during the early healing and proliferation phase in human ACL grafts, which might allow for the assumption that the mechanical properties are also substantially higher than in animal models during the first 3 postoperative months. Regardless of any model, whether human or animal, an adaptation of the healing graft toward the intact ACL occurs. However, a full restoration of either the biological or the mechanical properties of the intact ACL does not seem to be achieved. Still, clinical outcome studies have clearly shown that patients can return to even the most strenuous activities after primary ACL reconstruction at 6 months. This is confirmed by human biopsy studies that revealed an intact, fully viable graft at this time. However, no final conclusions can be made regarding the mechanical strength of healing ACL grafts in humans because techniques are not available for in vivo measurement of their mechanical properties. Even though the exact mechanisms that guide the ligamentization process are not fully understood, it seems to be most important that knee joint mechanics are restored by ACL reconstruction so that the loading conditions of the intact ACL are precisely replicated. Only if the reconstruction can restore the anatomy of the intact ACL will knee joint motion provide the same mechanical stimulus to the healing 414

ACL graft as to the intact ACL. Only then will adequate moderate remodeling occur that will maintain initial graft integrity and (partial) cell viability while initiating cellular and extracellular proliferation and differentiation to adapt the graft to its new biological and mechanical environment. The loading that is adequate for the graft at its different phases of healing will have to be determined so that it can continue to function as a “real” ACL in obtaining the exact loading environment as the intact ACL and thus eventually becoming a fully restored and not an adapted ACL. Future research will have to be directed toward (1) optimizing ACL reconstructions to fully restore ACL anatomy and function while providing the mechanical strength of the intact ACL; (2) developing biological treatment options that affect graft healing, especially during the early and proliferation phase, to optimize extracellular matrix remodeling; and (3) better differentiating the “good” from the “bad” remodeling changes so that the time to return to full activity without any restrictions can be reduced.

References 1. Amiel D, Kleiner JB, Roux RD, et al. The phenomenon of “ligamentization”: anterior cruciate ligament reconstruction with autogenous patellar tendon. J Orthop Res 1986;4:162–172. 2. Arnoczky SP, Tarvin GB, Marshall JL. Anterior cruciate ligament replacement using patellar tendon. An evaluation of graft revascularization in the dog. J Bone Joint Surg 1982;64A:217–224. 3. Ballock RT, Woo SL, Lyon RM, et al. Use of patellar tendon autograft for anterior cruciate ligament reconstruction in the rabbit: a long-term histologic and biomechanical study. J Orthop Res 1989;7:474–485. 4. Goradia VK, Rochat MC, Grana WA, et al. Tendon-to-bone healing of a semitendinosus tendon autograft used for ACL reconstruction in a sheep model. Am J Knee Surg 2000;13:143–151. 5. Grana WA, Egle DM, Mahnken, R, et al. An analysis of autograft fixation after anterior cruciate ligament reconstruction in a rabbit model. Am J Sports Med 1994;22:344–351. 6. Howell SM, Knox KE, Farley TE, Taylor MA. Revascularization of a human anterior cruciate ligament graft during the first two years of implantation. Am J Sports Med 1995;23:42–49. 7. Itoh S, Muneta T, Shinomiya K, et al. Electron microscopic evaluation of the effects of stress-shielding on maturation of the midsubstance and ligament-bone junction of the reconstructed anterior cruciate ligament in rabbits. J Mater Sci Mater Med 1999;10:185–190. 8. Jackson DW, Grood ES, Goldstein JD, et al. A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model. Am J Sports Med 1993;21:176–185. 9. Kleiner JB, Amiel D, Harwood FL, et al. Early histologic, metabolic, and vascular assessment of anterior cruciate ligament autografts. J Orthop Res 1989;7:235–242. 10. Kobayashi M, Watanabe N, Oshima Y, et al. The fate of host and graft cells in early healing of bone tunnel after tendon graft. Am J Sports Med 2005;33:1892–1897. 11. Kuroda R, Kurosaka M, Yoshiya S, et al. Localization of growth factors in the reconstructed anterior cruciate ligament: immunohistological study in dogs. Knee Surg Sports Traumatol Arthrosc 2000;8:120–126. 12. Liu SH, Panossian V, al-Shaikh R, et al. Morphology and matrix composition during early tendon to bone healing. Clin Orthop Relat Res 1997;339:253–260.

Graft Remodeling and Ligamentization After Anterior Cruciate Ligament Reconstruction 13. Papageorgiou CD, Ma CB, Abramowitch SD, et al. A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model. Am J Sports Med 2001;29:620–626. 14. Petersen W, Unterhauser F, Pufe T, et al. The angiogenic peptide vascular endothelial growth factor (VEGF) is expressed during the remodeling of free tendon grafts in sheep. Arch Orthop Trauma Surg 2003;123:168–174. 15. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75:1795–1803. 16. Rougraff BT, Shelbourne KD. Early histologic appearance of human patellar tendon autografts used for anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 1999;7:9–14. 17. Scheffler SU, Dustmann M, Gangéy I, et al. The biological healing and restoration of the mechanical properties of free soft-tissue allografts lag behind autologous ACL reconstruction in the sheep model. In Trans Orthop Res 2005;abstract #0236, Washington, DC. 18. Shino K, Kawasaki T, Hirose H, et al. Replacement of the anterior cruciate ligament by an allogeneic tendon graft. An experimental study in the dog. J Bone Joint Surg 1984;66B:672–681. 19. Tohyama H, Yasuda K. Extrinsic cell infiltration and revascularization accelerate mechanical deterioration of the patellar tendon after fibroblast necrosis. J Biomech Eng 2000;122:594–599. 20. Weiler A, Forster C, Hunt P, et al. The influence of locally applied platelet-derived growth factor-BB on free tendon graft remodeling after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:881–891. 21. Weiler A, Hoffmann RF, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135. 22. Weiler A, Peine R, Pashmineh-Azar A, et al. Tendon healing in a bone tunnel. Part I: biomechanical results after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:113–123. 23. Weiler A, Peters G, Maurer J, et al. Biomechanical properties and vascularity of an anterior cruciate ligament graft can be predicted by contrast-enhanced magnetic resonance imaging. A two-year study in sheep. Am J Sports Med 2001;29:751–761. 24. Yoshikawa T, Tohyama H, Enomoto H, et al. Temporal changes in relationships between fibroblast repopulation, VEGF expression and angiogenesis in the patellar tendon graft after anterior cruciate ligament reconstruction. In Trans Orthop Res 2004;abstract #0236, San Francisco. 25. Roux W. Die Entwicklungsmechanik; ein neuer Zweig der biologischen Wissenschaft. Leipzig, 1905, Wilhelm Engelmann. 26. Amiel D, Frank C, Harwood F, et al. Tendons and ligaments: a morphological and biochemical comparison. J Orthop Res 1984;1:257–265. 27. Blickenstaff KR, Grana WA, Egle D. Analysis of a semitendinosus autograft in a rabbit model. Am J Sports Med 1997;25:554–559. 28. Liu SH, Yang RS, al-Shaikh R, et al. Collagen in tendon, ligament, and bone healing. A current review. Clin Orthop Relat Res 1995;318:265–278. 29. Tomita F, Yasuda K, Mikami S, et al. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bonepatellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy 2001;17:461–476. 30. Bosch U, Kasperczyk WJ. Healing of the patellar tendon autograft after posterior cruciate ligament reconstruction–a process of ligamentization? An experimental study in a sheep model. Am J Sports Med 1992;20:558–566. 31. Kleiner JB, Amiel D, Roux RD, et al. Origin of replacement cells for the anterior cruciate ligament autograft. J Orthop Res 1986;4:466–474. 32. Shino K, Horibe S. Experimental ligament reconstruction by allogenic tendon graft in a canine model. Acta Orthop Belg 1991;57:44–53. 33. Yoshikawa T, Tohyama H, Katsura T, et al. Local administration of VEGF enhances mechanical deterioration of the tendon grafted to reconstruct the ACL, although it accelerates angionesis and cellularity

34. 35.

36.

37.

38.

39.

40.

41. 42.

43.

44.

45.

46.

47.

48.

49.

50.

51.

52.

53.

54.

55

and infiltration: a sheep model study. In Trans Orthop Res 2005; abstract #0320, Washington, DC. Kawamura S, Ying L, Kim HJ, et al. Macrophages accumulate in the early phase of tendon-bone healing. J Orthop Res 2005;23:1425–1432. Goradia VK, Rochat MC, Kida M, et al. Natural history of a hamstring tendon autograft used for anterior cruciate ligament reconstruction in a sheep model. Am J Sports Med 2000;28:40–46. Ohno K, Yasuda K, Yamamoto N, et al. Effects of complete stressshielding on the mechanical properties and histology of in situ frozen patellar tendon. J Orthop Res 1993;11:592–602. Majima T, Yasuda K, Yamamoto N, et al. Deterioration of mechanical properties of the autograft in controlled stress-shielded augmentation procedures. An experimental study with rabbit patellar tendon. Am J Sports Med 1994;22:821–829. Majima T, Yasuda K, Tsuchida T, et al. Stress shielding of patellar tendon: effect on small-diameter collagen fibrils in a rabbit model. J Orthop Sci 2003;8:836–841. Flint MH, Craig AS, Reilly HC, et al. Collagen fibril diameters and glycosaminoglycan content of skins–indices of tissue maturity and function. Connect Tissue Res 1984;13:69–81. Parry DA, Barnes GR, Craig AS. A comparison of the size distribution of collagen fibrils in connective tissues as a function of age and a possible relation between fibril size distribution and mechanical properties. Proc Roy Soc Lond B Biol Sci 1978;203:305–321. Tohyama H, Yasuda K. The effect of increased stress on the patellar tendon. J Bone Joint Surg 2002;84B:440–446. Unterhauser FN, Bail HJ, Hoher J, et al. Endoligamentous revascularization of an anterior cruciate ligament graft. Clin Orthop Relat Res 2003;414:276–288. Unterhauser FN, Bosch U, Zeichen J, et al. Alpha-smooth muscle actin containing contractile fibroblastic cells in human knee arthrofibrosis tissue. Winner of the AGA-DonJoy Award 2003. Arch Orthop Trauma Surg 2004;124:585–591. Weiler A, Unterhauser FN, Bail HJ, et al. Alpha-smooth muscle actin is expressed by fibroblastic cells of the ovine anterior cruciate ligament and its free tendon graft during remodeling. J Orthop Res 2002;20:310–317. Murray MM, Martin SD, Martin TL, et al. Histological changes in the human anterior cruciate ligament after rupture. J Bone Joint Surg 2000;82A:1387–1397. Clancy WG Jr, Narechania RG, Rosenberg TD, et al. Anterior and posterior cruciate ligament reconstruction in rhesus monkeys. J Bone Joint Surg 1981;63A:1270–1284. Jackson JR, Minton JA, Ho ML, et al. Expression of vascular endothelial growth factor in synovial fibroblasts is induced by hypoxia and interleukin 1beta. J Rheumatol 1997;24:1253–1259. Spindler KP, Andrish JT, Miller RR, et al. Distribution of cellular repopulation and collagen synthesis in a canine anterior cruciate ligament autograft. J Orthop Res 1996;14:384–389. Jackson DW, Grood ES, Cohn BT, et al. The effects of in situ freezing on the anterior cruciate ligament. An experimental study in goats. J Bone Joint Surg 1991;73:201–213. Tsuchida T, Yasuda K, Kaneda K, et al. Effects of in situ freezing and stress-shielding on the ultrastructure of rabbit patellar tendons. J Orthop Res 1997;15:904–910. Bosch U, Kasperczyk WJ, Oestern HJ, et al. The patellar tendon graft for PCL reconstruction. Morphological aspects in a sheep model. Acta Orthop Belg 1994;60:57–61. Johnson LL. The outcome of a free autogenous semitendinosus tendon graft in human anterior cruciate reconstructive surgery: a histological study. Arthroscopy 1993;9:131–142. Ng GY, Oakes BW, Deacon OW, et al. Long-term study of the biochemistry and biomechanics of anterior cruciate ligament-patellar tendon autografts in goats. J Orthop Res 1996;14:851–856. Abe S, Kurosaka M, Iguchi T, et al. Light and electron microscopic study of remodeling and maturation process in autogenous graft for anterior cruciate ligament reconstruction. Arthroscopy 1993;9:394–405.

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Anterior Cruciate Ligament Reconstruction 55. Petersen W, Laprell H. Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts. Knee Surg Sports Traumatol Arthrosc 2000;8:26–31. 56. Ng GY, Oakes BW, Deacon OW, et al. Biomechanics of patellar tendon autograft for reconstruction of the anterior cruciate ligament in the goat: three-year study. J Orthop Res 1995;13:602–608. 57. Rougraff B, Shelbourne KD, Gerth PK, et al. Arthroscopic and histologic analysis of human patellar tendon autografts used for anterior cruciate ligament reconstruction. Am J Sports Med 1993;21:277–284.

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58. Falconiero RP, DiStefano VJ, Cook TM. Revascularization and ligamentization of autogenous anterior cruciate ligament grafts in humans. Arthroscopy 1998;14:197–205. 59. Marumo K, Saito M, Yamagishi T, et al. The “ligamentization” process in human anterior cruciate ligament reconstruction with autogenous patellar and hamstring tendons: a biochemical study. Am J Sports Med 2005;33:1166–1173. 60. Cho S, Muneta T, Ito S, et al. Electron microscopic evaluation of two-bundle anatomically reconstructed anterior cruciate ligament graft. J Orthop Sci 2004;9:296–301.

Graft-Tunnel Healing Tendon graft healing within the bone tunnel is one of the most important factors affecting “ligamentization” of the anterior cruciate ligament (ACL) graft, as it contributes to determine the mechanical behavior of the femur–ACL graft– tibia complex. The normal ACL attaches to the bone through a direct-type insertion, which has a highly differentiated morphology. In fact, within 1 mm, four different layers can be recognized: fibrous tissue, fibrocartilage, mineralized fibrocartilage, and bone (Fig. 56-1). This region plays an important mechanical role, as it allows a progressive distribution of the tensile load from a soft tissue (ligament) to a hard tissue (bone). Several clinical and experimental studies have shown that after ACL reconstruction, tendon graft heals within the bone tunnel by the formation of a bone–graft junction. Biological, histological, and biomechanical features of this healing process can vary depending on many variables.

HUMAN STUDIES Despite the large amount of animal studies on bone–tendon graft healing in ACL reconstruction, very few investigations in humans have been reported on this issue. Pinczewski et al1 reported on two biopsies at the bone–graft interface on patients who underwent revision ACL surgery for a traumatic graft failure at 6 and 10 weeks after initial reconstruction with doubled hamstring tendon (HT) graft and fixation with metal interference screws. They described graft integration

by way of collagen fibers resembling Sharpey fibers between tendon and bone. Petersen and Laprell2 compared bone–tendon graft healing after ACL reconstruction between the patellar tendon (PT) and HT on biopsy specimens obtained at ACL revision surgery from 14 patients. They observed that the PT graft healed within bone tunnel by bone plug incorporation, maintaining a direct-type insertion at the native bone plug–tendon junction. Tendon–bone healing occurred by formation of a fibrous insertion with no evidence of fibrocartilage. Ishibashi et al3 examined the histological changes in PT autografts at the tibial tunnel in biopsy specimens retrieved during revision surgery after ACL reconstruction in 10 patients. They observed that in the early revisions (less than 1 year from prior reconstruction), the bone–tendon junction was still immature, with presence of granulation tissue between the tendon and the tunnel wall; in the late revisions (more than 1 year), the original bone–tendon junction was not seen, and the tendon continued completely to the tunnel wall with Sharpey-like fibers. Nebelung et al4 obtained biopsies from the femoral tunnel in five patients at 6 to 14 months after ACL reconstruction with HT. Fixation was performed in four patients with a suspension device (Endobutton or TransFix) and in one patient with an interference screw. At histology of the four reconstructions with a suspension device, biopsies resembled granulation tissue without continuity of collagen fibers between the graft and the bony wall. In contrast, in the graft fixed with interference screws, a metaplastic fibrous cartilage between

56 CHAPTER

Giuseppe Milano Laura Deriu Carlo Fabbriciani

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Anterior Cruciate Ligament Reconstruction patients with an ACL graft failure who underwent revision surgery. Because failed graft incorporation can be advocated as a cause of reinjury after ACL reconstruction, even in the presence of a traumatic event, we cannot exclude the theory that some findings observed in bioptic specimens were affected by a disturbance of the healing process of the graft within the bone tunnel. Therefore the clinical relevance of the information reported in these studies is somewhat debatable.

ANIMAL STUDIES

FIG. 56-1 Histological section of a direct-type bone-ligament insertion. Between bone (B) and tendon (T) a transitional fibrocartilaginous layer (FC) can be seen (Gomori-Halmi staining, 20).

the tendon graft and the lamellar bone was noted. The authors hypothesized that suspensory fixation can produce micromotion at the tendon–bone interface, which can impair graft healing within the bone tunnel. Robert et al5 performed 12 biopsies on patients undergoing an arthroscopy between 3 and 20 months after ACL reconstruction with HT and femoral fixation with a suspension device (TransFix). Histological analysis at 3 months showed a fibrovascular interface and an uncalcified osteoid with very few collagen fibers between the tendon and the bone. At 5 and 6 months, some Sharpey-like fibers and less immature woven bone were seen. Maturity of insertion with numerous Sharpey fibers at the tendon–bone interface was seen by 10 months. After 1 year, the tendon–bone interface was composed of a continuous layer of Sharpey-like fibers. In three cases, no contact was seen at biopsy despite good clinical stability at 1 year. The authors concluded that suspensory femoral fixation of HT graft produces an indirect fixation that reaches maturity 10 to 12 months after reconstruction. All the previously mentioned studies are based on histological examination of biopsy specimens retrieved from 418

Several animal studies have been performed to evaluate the healing of a tendon graft within a bone tunnel. Although the findings reported in experimental studies have a certain clinical relevance, they cannot be entirely applied to the clinical environment because animals have a different knee kinematics in comparison with humans and are usually treated without a controlled postoperative regimen. Moreover, animal studies on bone–tendon healing frequently differ in some methodological aspects, which merit discussion. First, experimental studies on bone–tendon healing are based on two different models: an extraarticular model and an intraarticular model. The extraarticular model consists of a tendon graft that is detached from one of its insertions and fixed within a drilled tunnel of an adjacent bone (i.e., the digital extensor tendon detached proximally and fixed within a bone tunnel in the proximal tibia). In the intraarticular model, an ACL reconstruction is performed using a free tendon graft (i.e., the semitendinosus tendon) or the central third of the PT. This model better reproduces the ACL reconstruction in humans. In fact, the extraarticular model does not consider the biological stimuli of the intraarticular environment that may influence graft healing within the tunnel. Second, experimental settings can vary according to the animal model selected, as knee kinematics of an animal model can be more or less similar to that of the human knee; furthermore, the material properties of the tendon graft selected for reconstruction in comparison with those of native ACL can influence the results of the study. Third, studies on tendon–bone healing differ in the methods of investigation of the results. Several authors performed a histological examination of the bone–tendon graft interface,6–13 whereas others focused on the mechanical properties of the bone–tendon graft complex.14–19 It has to be considered that most of the biomechanical studies were based on a load-to-failure (LTF) testing of the femur–graft–tibia complex and did not consider the effect of primary fixation on the structural properties of the complex. For this reason, some authors have performed mechanical testing after

Graft-Tunnel Healing removal of the fixation devices in order to quantify the mechanical role of bone–tendon graft interface.14,15,17–19 Moreover, almost all the experimental studies performed histological and/or biomechanical evaluations at different time intervals, and although some authors evaluated the long-term fate of tendon graft healing within a bone tunnel,8,10,11,13,16,20 most authors focused on the first 12 weeks after surgery because of the clinical relevance of this period for planning postoperative rehabilitation and return to physical activity. Finally, the number and type of variables correlated to the outcome greatly differ among the various studies, so it is necessary to consider in detail the results reported in the literature in order to better understand which factors can affect the healing process of a tendon graft within a bone tunnel.

Type of Graft Several experiment studies focused their attention on histological and biomechanical findings of bone–tendon graft healing according to the type of tendon graft. The first reports on tendon graft healing within a bone tunnel showed that it happens through bone apposition at the tunnel wall and formation of fibrous tissue at the bone–graft interface, which matures with time and anchors the graft to the bone.21–23 More recent studies on extraarticular animal models6,9 demonstrated that tendon graft heals within a bone tunnel by formation of an indirect-type junction composed of a fibrous tissue containing perpendicular collagen fibers resembling Sharpey-like fibers that penetrate into the bone, without a transitional fibrocartilaginous layer between tendon and bone (Fig. 56-2). In a biomechanical analysis, Rodeo et al6 showed that until 8 weeks after surgery, the

FIG. 56-2 Histological section of an indirect-type bone-ligament insertion. The fibrous tissue (T) attaches to the bone (B) without a transitional fibrocartilaginous layer (Gomori-Halmi staining, 20).

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healing tissue at the bone–graft interface was not mechanically competent and the graft failed due to pullout from the tunnel. Experimental studies performed on intraarticular models of ACL reconstruction with single or doubled semitendinosus tendon graft confirmed that even an autologous ACL graft heals within the bone tunnel by formation of an indirect-type junction at the bone–graft interface, with Sharpey-like fibers perpendicular to the tunnel wall.7,8,11 The newly formed insertion was evident 8 weeks after surgery and completed after 24 weeks. However, biomechanical testing showed that the graft remains weak within 1 year after surgery, with a mean failure load ranging from 25% to 50% of the normal ACL. Regarding the tensile strength of the bone–tendon graft junction, Grana et al,7 using a single-strand semitendinosus tendon graft in a rabbit model, observed that during the first 3 weeks after surgery the graft suffered a rapid and dramatic loss of its mechanical properties and failed mostly at its midsubstance rather than due to pullout from the tunnel. On the contrary, Goradia et al,11 using a doubled semitendinosus tendon graft in a sheep model, observed that up to 12 weeks, graft failure occurred by pullout from the bone tunnel. Therefore they stated that for as long as 3 months after surgery, the graft has not completely healed within the bone tunnel. Other authors10,12,15 focused their attention on the healing process of grafts with bone plugs, such as the patellar tendon, within a bone tunnel (bone–bone healing). They observed that graft healing occurs differently for the bone plug and the intraosseous tendinous portion of the graft. In fact, bone plug incorporation at the tunnel wall occurs through a progression of necrosis, resorption, and remodeling, and after 3 months it is no longer distinguishable from the surrounding bone. The intraosseous tendinous portion of the graft heals to the bone tunnel by formation of an indirect-type insertion with penetrating collagen fibers that appear well organized by 3 months after surgery, similarly to the healing process observed for free tendon grafts. The native bone–tendon junction of the graft shows degeneration of the fibrocartilaginous layer by 6 weeks, which is during the phase of bone plug remodeling. However, by 6 months it appears to be redifferentiated with four distinct zones. Comparative studies between tendon–bone and bone–bone healing on intraarticular models of ACL reconstruction confirmed similar histological findings.14,15,24 However, biomechanical testing demonstrated that bone– bone healing occurs more rapidly than tendon–bone healing. In fact, up to 3 weeks, both soft tissue and bone plug tendon grafts fail due to pullout from the bone tunnel. Between 6 and 8 weeks after surgery, the bone–bone interface appears mechanically stronger than the tendon–bone interface, but this difference is no more significant by 12 weeks. These 419

Anterior Cruciate Ligament Reconstruction observations led the authors to conclude that soft tissue grafts such as hamstring tendons heal more slowly than PT within the bone tunnel after ACL reconstruction; therefore the fixation device for soft tissue tendon grafts is more important than comparing it to PT graft during the first weeks after surgery. Regarding the tendon allograft, experimental studies showed that the bone–graft healing process is similar to that observed for autografts.20,25,26 However, it occurs more slowly and the newly formed bone–tendon junction is evident only after a period varying from 18 weeks to 6 months after surgery. This delayed healing process should be related to the inflammatory response to the allogenic material, which persists for a long time around the graft20 and probably leads to the tunnel-widening phenomenon that mainly occurs during the first weeks after surgery.26

Bone Quality Another variable that can influence tendon graft healing is the quality of bone where the graft is fixed. It is well known that bone density is different between the distal femur and the proximal tibia; this could affect the quality and rate of incorporation of tendon graft at the cancellous bone surface of the tunnel wall. Some authors11,27 investigated this feature of bone–tendon graft healing on experimental intraarticular and extraarticular models; however, the role of bone quality on bone–tendon graft healing remains unclear. Goradia et al11 performed an ACL reconstruction with doubled semitendinosus tendon graft and did not observe histological differences in tendon–bone healing between the femoral and tibial tunnel at each interval (from 2 to 52 weeks). On the contrary, Grassman et al,27 using the semitendinosus tendon graft for extraarticular reconstruction of the medial collateral ligament in a rabbit model, observed that incorporation and remodeling of the graft within the bone tunnels were much more extensive at the cancellous-filled femoral bone–graft interface than within the marrow-dominated tibial tunnel, thus suggesting that tendon graft healing may depend on the cancellous bone architecture at the bone–graft interface.

Fixation Technique Most studies performed to evaluate tendon–bone healing did not consider graft fixation technique as a factor affecting the healing process. Particularly, many authors reported the use of periosteal or transosseous sutures for graft fixation.6–9,28 This fixation technique cannot guarantee high structural properties of the bone–tendon graft complex before biological fixation has occurred. Recently, some authors investigated the role of primary fixation on bone–tendon

420

healing, reproducing in animal models some fixation techniques currently used in humans for ACL tendon grafts. Weiler et al13,16 performed a histological and biomechanical evaluation of healing of a tendon graft fixed within the tibial tunnel with an interference fit screw (1 mm larger than the tunnel) after an ACL reconstruction with autologous Achilles tendon split graft in a sheep model. They observed that bone–tendon healing, under the compressive effect of the interference screw, progressed partially by direct contact without development of a fibrous transition interface, whereas at the articular tunnel aperture site a well-differentiated, direct-type junction was evident by 24 weeks.13 Biomechanical testing16 showed that at 6 and 9 weeks, all grafts failed at the screw insertion site. By 24 weeks, grafts failed by osteocartilaginous avulsion from the tibial attachment site. These findings indicate that interference fit fixation may compromise the mechanical properties of the graft in the early healing phase at the screw insertion site, but the compressive effect of the screw supplies a biological stimulus toward the formation of a physiological, direct–type bone–graft insertion. Singhatat et al17 used an extraarticular reconstruction model in ovine tibiae to evaluate the effect of the fixation technique on the mechanical properties of a bone–tendon graft complex, comparing two different fixation devices: an absorbable interference screw and a spiked screw and washer (WasherLoc). They observed that the strength of biological fixation of tendon to bone increased slower with the interference screw than with the screw and washer. In fact, tensile testing on tendon graft–bone tunnel interface (after removing the fixation device) after 4 weeks of implantation showed that with interference fixation, mean strength and stiffness were respectively 31% and 36% of that observed for the complex at implantation (time zero). With WasherLoc fixation, strength and stiffness were respectively 50% and 143% of the complex at implantation. The authors supposed that interference fixation might impair tendon healing within the bone tunnel as it decreased the contact area between the tendon and the surrounding bone. Furthermore, the compressive effect of the interference screw on the tendon graft may prevent the ingrowth of blood vessels along the entire length of the tendon graft. However, this hypothesis was not confirmed in this study by a histological examination.

Gap Size Another important factor related to bone–tendon healing is the gap between the tendon graft and the walls of the bone tunnel. This is important especially in ACL reconstruction with doubled HT graft and suspensory femoral fixation devices, such as Endobutton or TransFix, as these fixation devices do not produce any compressive effect on the

Graft-Tunnel Healing intraosseous portion of the graft, and therefore the thickness of the healing tissue at the bone–tendon interface depends on the size of the gap between the graft and the bone at the time of reconstruction. Tien et al29 evaluated the effect of gap size on the tendon-to-bone healing on ACL reconstruction with autologous semitendinosus tendon graft in a rabbit model and observed that healing tissue at the bone–tendon interface appeared denser and more organized in the specimens with a smaller gap. Tensile testing at 2 weeks confirmed a significantly greater maximal tensile strength for specimens in which the tunnel had the same diameter of the graft than for specimens with a tunnel 25% to 33% larger than the graft. Greis et al,28 using an extraarticular bone–tendon healing model in dogs, reported similar data. They observed that the failure load of tendon–bone complex was significantly greater when the bone tunnel approximated the diameter of the tendon graft (4.2 mm) in comparison with specimens with a 6-mm tunnel. On the contrary, Yamazaki et al30 in an experimental study in dogs observed that a free tendon graft used for ACL reconstruction healed in a bone tunnel that was 2 mm larger than the graft by formation of a connective transitional fibrous layer that was denser and better organized than that observed in specimens with a bone tunnel having the same diameter as the graft. Moreover, mechanical analysis showed that at 3 and 6 weeks, the differences in ultimate failure load and failure mode between the two groups of specimens were not significant.

Mechanical Stresses Indeed, mechanical stresses influence healing of a tendon graft within a bone tunnel. As previously reported, fixation technique and gap size can influence graft healing because they can modify the loads applied to the intraosseous portion of the graft. However, it is unclear how magnitude and direction of loads applied to the graft can affect the quality and rate of the healing process. Regarding load magnitude, it is important to distinguish between loads applied during healing time and initial tensile load due to graft tensioning at the time of surgery. Sakai et al31 investigated the effect of immobilization on the biological fixation of a tendon graft within the bone tunnel after ACL reconstruction in a rabbit model and showed that no immobilization delays the bone–tendon healing and impairs the mechanical strength of the newly formed bone– graft junction. Abramowitch et al32 evaluated the effect of initial graft tension on the tensile properties of an ACL graft in a goat model and observed that high initial tension of the ACL graft better replicated a normal knee kinematics immediately after reconstruction in comparison with a low graft tension; however, this effect diminished during the early graft healing process.

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Some interesting findings regarding the effect of direction of loads applied to the graft on bone–tendon graft healing are reported by Yamakado et al,33 who showed that tendon–bone healing responds to mechanical stress applied to the tendon graft. In an extraarticular tendon graft reconstruction in a rabbit model, they observed that tensile stress enhances the healing process of the bone–tendon junction, compressive stress promotes chondroid formation, and shear load has little or no effect on regeneration of the bone– tendon junction. These forces are differently distributed along the bone–tendon graft interface and according to the direction of tunnel in relation to the axis of the intraarticular portion of the tendon graft.

Authors’ Experience We analyzed in a sheep model the mechanical behavior of the tendon graft–bone interface on ACL reconstruction, comparing patellar tendon (Group 1) and a free tendon graft (Group 2) using the doubled lateral extensor of toes (DLET).18 Femoral fixation was achieved in all specimens with a transverse fixation: a metal setscrew for the PT graft, and a modified TransFix for the DLET graft. On the tibia, the graft was fixed with an absorbable interference screw in both groups. Animals were sacrificed after 1, 2, 3, and 6 months postsurgery, and an LTF mechanical testing on the femur–graft–tibia complex (FGTC) was performed after removing (Subgroup A) or maintaining (Subgroup B) the femoral fixation device in order to evaluate the mechanical properties of the proximal tendon graft–bone tunnel interface and the contribution of the fixation device over time. Specimens were compared with control groups that consisted of normal ACL, normal grafts, and reconstructions at time zero. Results of the mechanical testing performed on the control (Table 56-1) and treated groups (Table 56-2) showed a similar trend in the variation of the structural properties of the two groups in comparison with the controls. At 1 month, mean failure load dramatically decreased. After this period, we observed a significant increase, although the variation between the second and the third month was not significant. Mean stiffness showed a dramatic decrease at 1 and 2 months, whereas in the 3-month samples a significant increase occurred. However, at 2 and 3 months, the structural properties of the treated groups remained significantly lower than the control groups. At 6 months, we observed a significant improvement of the structural properties in both groups, much greater than that reported in previous studies.8,11,16 In fact, 6 months after surgery, the PT graft showed a good recovery of its original structural properties and also approximated the strength (about 83%) and stiffness (about 107% to 109%) of a normal ACL. The DLET graft at 6 months 421

Anterior Cruciate Ligament Reconstruction TABLE 56-1 Results of Load-to-Failure Tests on the Control Groups (Mean  SD) Failure Load (N)

Stiffness (N/mm)

Normal ACL

723.0  12.1

156.6  6.1

Normal PT

830.1  16.6

176.8  9.3

Time zero: PT

607.8  14.4

89.8  5.9

Normal DLET

1139.8  44.5

285.7  22.6

Time zero: DLET

1032.8  43.7

210.1  15.5

ACL, Anterior cruciate ligament; DLET, doubled lateral extensor of toes; PT, patellar tendon; SD, standard deviation.

showed a severe impairment of its original structural properties. However, strength and stiffness were about 80% and 110% of a normal ACL, respectively. When comparing the structural properties of the femur–PT graft–tibia complex with and without a femoral fixation device, we did not observe significant differences for all the variables considered at every time interval. This would imply that the presence of the fixation device did not influence the mechanical behavior of the FGTC. On the contrary, comparison between the two DLET subgroups, with and without the fixation device, showed a significant difference for mean failure load and stiffness in the 1-month samples. Furthermore, on comparison of the specimens of the two groups in which the femoral fixation devices had been removed before the mechanical test (Subgroup A), we observed that at 1 month the structural properties of the PT group were significantly greater than the DLET group. For the following time intervals, the structural properties of the two types of graft did not significantly differ. Analysis of the failure mode in specimens without the fixation device showed that at 1 month, PT graft failure always occurred at its intraarticular part, whereas the DLET grafts failed by means of pullout from the femoral tunnel. In the following time intervals, the grafts always ruptured at their midsubstance in both groups. This would demonstrate that the bone plug of the PT graft incorporated in the femoral

tunnel in an early phase after ACL reconstruction, making the bone–graft junction mechanically competent after 1 month, probably due to the compression effect of transverse fixation that accelerated bone–bone healing. On the contrary, the DLET graft was not yet incorporated in the femoral tunnel 1 month after surgery; therefore, in absence of the fixation device, it slipped out of the tunnel when submitted to traction. Although our study was based on an animal model, we believe that some observations have some clinical relevance. First, 6 months after ACL reconstruction, both PT and doubled free tendon grafts are less strong (about 80%) but stiffer (about 110%) than normal ACL, and thus they may be considered as valid substitutes of the ACL. Second, although the bone plug of the PT graft allows a faster incorporation of the graft within the bone tunnel, it does not improve the mechanical properties of the FGTC. Third, doubled free tendon grafts need high fixation strength and stiffness because they require more than 4 weeks to heal into the bone tunnel. Finally, the use of fixation devices that guarantee a high fixation strength and stiffness does not allow acceleration of the postoperative rehabilitation, as primary fixation has a determinant mechanical role only during the first weeks after surgery.

FUTURE DIRECTIONS In recent years, numerous experimental studies have been carried out to evaluate the effects of exogenous factors on healing of a tendon graft within a bone tunnel, using both extraarticular and intraarticular experimental models. These studies focused on two different goals: (1) to accelerate tendon–bone healing by increasing bone apposition around the tendon graft and new formation of collagen fibers at the bone–graft interface, with the aim of allowing early postoperative return to normal daily activities as well as sports and reducing the risk of graft failure due to pullout from the bone tunnel, and (2) to promote differentiation of the newly

TABLE 56-2 Results of Load-to-Failure Tests on the Treated Subgroups (Mean  SD) Failure Load (N) Subgroup

1A

2A

2B

1A

1B

2A

2B

1 month

41.8  2.4

43.2  3.0

25.6  4.0

39.7  8.9

30.7  3.3

31.0  3.1

18.2  2.9

29.5  4.1

2 months

165.1  14.4

163.5  10.5

168.6  18.1

171.2  14.0

31.5  2.0

31.2  2.1

30.2  3.0

31.5  2.5

3 months

185.3  17.5

184.9  11.8

179.9  14.3

187.8  16.7

48.6  6.2

49.0  4.5

50.5  4.8

53.0  6.0

6 months

602.9  29.0

600.7  11.0

578.0  15.7

583.7  28.2

167.9  8.4

171.3  10.0

172.3  13.5

170.7  11.3

SD, Standard deviation.

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1B

Stiffness (N/mm)

Graft-Tunnel Healing formed bone–tendon junction into a direct-type insertion as similar as possible to that of normal ACL in order to obtain a more physiological distribution of tensile forces between the intraarticular part of the graft and its insertion to the bone. Although these exogenous factors showed promising results, they cannot yet be widely applied to ACL surgery because they require further investigation to optimize delivery techniques, therapeutic concentrations, and maintenance of therapeutic effects with time and to reduce the risk of undesirable effects.

Bone Proteins and Growth Factors Several studies have shown the effect of some polypeptides including bone morphogenetic proteins (BMPs) and growth factors (GFs), such as transforming growth factors (TGFs), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), and epidermal growth factor (EGF), on the activation and regulation of proliferation and differentiation of bone and fibrous and cartilaginous tissues.34–36 Based on these experiences, some authors investigated the role of BMPs and GFs in promoting tendon–bone healing through the activation and acceleration of bone ingrowth, collagen fiber synthesis, and fibrocartilaginous differentiation at the bone–tendon graft interface, with the aim of obtaining early formation of bone–tendon insertion similar to that of normal ACL. Rodeo et al37 reported the effect of locally applied BMP-2 on tendon healing in bone tunnel in dogs. They showed that animals treated with recombinant human BMP-2 had radiographic evidence of more extensive formation and closer apposition of new bone around the tendon graft in comparison with controls. Biomechanical analysis confirmed higher pullout strength in BMP-treated specimens. Anderson et al38 reported an experimental study on ACL reconstruction with autologous semitendinosus tendon graft in a rabbit model, using a collagen sponge wrapped around the portion of the graft inside the bone tunnel as a carrier vehicle to release a bone-derived extract that contained several bone morphogenetic proteins (BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, and BMP-7) and growth factors with known osteoinductive activity or that can modulate bone formation, such as TGF-ß1, TGF-ß2, TGF-ß3, and FGF. Although this mixture of bone-derived proteins did not allow the effects of each protein on tendon–bone healing to be discriminated, the authors observed that animals treated with bone-derived proteins had a histological appearance of a more consistent, dense interface tissue and closer apposition of new bone to the graft, with occasional formation of a fibrocartilaginous interface, when compared with control specimens at 2, 4, and 8 weeks after surgery. Biomechanical analysis demonstrated a significant increase in ultimate tensile strength of the

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treated grafts (from 47% more than controls at 2 weeks to 80% at 8 weeks). Mihelic et al39 reported a study on ACL reconstruction with autologous peroneus tertius tendon graft in a sheep model. They applied a carrier sponge with recombinant human BMP-7 to the bone–tendon graft interface and observed that bone formation and remodeling around the graft at 3 and 6 weeks after surgery were more extensive in knees treated with BMP-7 compared with control knees. Mechanical testing showed a significantly greater tensile strength in grafts treated with BMP-7 than in control specimens. Yamazaki et al19 performed an experimental study in dogs to detect the effect of TGF-ß1 on healing of the flexor tendon autograft in ACL reconstruction. TGF-ß1 was mixed with fibrin sealant and applied in the graft–bone gap of the tibial tunnel. At 3 weeks, histological examination showed that perpendicular collagen fibers connecting the tendon to the bone (resembling Sharpey fibers) were richly generated in knees treated with TGF-ß1 compared with control knees. In mechanical pullout testing after removing tibial graft fixation, the ultimate failure load and stiffness of the graft–tibia complex of knees treated with TGF-ß1 were significantly higher than those of controls.

Gene Therapy Some limits in the intraarticular use of bone proteins and growth factors are represented by their short half-life and removal by synovial fluid that can affect the maintenance of therapeutic local concentrations. For this reason, some researchers have attempted to develop techniques of gene transfer, consisting of the injection of transduced cells that express genes for synthesis of desired proteins (i.e., growth factors) at high local concentration for prolonged time periods. These techniques have been applied to enhance tendon–bone healing. Martinek et al40 reported a study on genetically engineered semitendinosus tendon grafts used for ACL reconstruction in rabbits to evaluate the capacity of BMP-2 gene transfer to improve healing of a tendon graft in the bone tunnel. They observed that at 6 weeks, grafts infected with adenovirus-BMP-2 (AdBMP-2) had broad zones of a newly formed transition layer at the bone–graft interface, resembling a direct-type insertion. Mechanical testing showed that ultimate failure load and stiffness of grafts infected with AdBMP-2 were significantly greater than controls. This study was highly remarkable, as it showed that sustained and prolonged local BMP-2 delivery using gene transfer modality created a bone–tendon graft insertion similar to that of a normal ACL. However, many questions need to be answered regarding safety and regulatory issues before gene transfer is suggested as a therapeutic method in orthopaedics.41

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Anterior Cruciate Ligament Reconstruction

Inhibitors of Matrix Metalloproteinases Matrix metalloproteinases (MMPs) such as collagenases and stromelysins are zinc-dependent enzymes that have a catalytic effect on connective tissues by degrading different types of collagen. These enzymes are increased in the intraarticular environment in the acute phase following ACL rupture and are presumably increased following ACL reconstruction. Therefore it seems likely that MMPs have an adverse effect on tendon–bone healing that occurs by formation of collagen fibers at the bone–graft interface. For these reasons, some authors42,43 have hypothesized that tissue inhibitors of metalloproteinases (TIMPs) could have a potential positive effect on the healing process of a tendon graft within a bone tunnel. Demirag et al43 tested the potential enhancement effect of a-2 macroglobuline on bone–tendon healing of ACL graft by blockage of synovial MMP activity in a rabbit model. They injected a-2 macroglobuline into the knee joint after ACL reconstruction with semitendinosus tendon autograft to block the MMPs in the synovial fluid and observed after 2 and 5 weeks a significantly decreased concentration of type I collagenase (MMP-8) in the synovial fluid compared with the control group. Histological examination showed that the bone–tendon interface within the tunnel in the treated specimens had more areas of denser connective tissue ingrowth compared with the controls. Mechanical testing showed that the mean ultimate failure load of treated specimens was significantly greater than control specimens at both 2 and 5 weeks.

Cell Therapy Some authors have investigated the effects of mesenchymal stem cells (MSCs) on the quality and rate of a tendon graft osteointegration.44,45 MSCs are pluripotent cells that can be harvested from bone marrow of the iliac crest, isolated and cultured in vitro, included in a fibrin gel as carrier, and applied along the bone–tendon graft interface. Ouyang et al,44 in an extraarticular rabbit model, showed the presence of discontinuous areas of fibrocartilage-like tissue containing type II collagen at the bone–graft interface by 4 weeks after surgery. Lim et al45 reported similar results on an experimental model of ACL reconstruction. By 2 weeks, they observed large areas of cartilage at the newly formed bone–graft junction with histological features similar to those of the normal ACL by 8 weeks. Mechanical testing showed that the tensile strength of the grafts treated with stem cells was significantly greater than controls by 8 weeks.

Biological Scaffolds Some authors have focused their attention on the use of periosteal grafts to enhance tendon graft healing within a 424

bone tunnel.46–49 Periosteum is an osteogenic tissue that modulates bone formation and remodeling at the cortical bone surface. Therefore it was hypothesized that periosteum should behave as a biological scaffold to promote and accelerate bone–tendon graft healing. Experimental studies on extraarticular models in rabbits evaluated histological and biomechanical features of tendon grafts wrapped in periosteum in the intraosseous part. They showed that periosteum promotes a more extensive and closer apposition of new bone around the tendon graft.48 Moreover, a bone–tendon fibrocartilaginous insertion has been observed by 4 to 12 weeks after surgery.46,47 It was reported that a biological effect of periosteum on bone–tendon graft healing is more evident when the cambial layer of the scaffold faced the tunnel wall49 and that fresh periosteal graft is more effective than freshfrozen graft.46 Biomechanical testing showed controversial results regarding the mechanical strength of biological fixation in the early phase after surgery. In fact, Kyung et al48 reported that the mean pullout strength of periosteum-treated grafts was significantly greater than controls at 3 and 6 weeks. On the contrary, Chen et al47 observed that at 4 weeks the difference in tensile strength between periosteum-treated grafts and controls was not significant and graft failure at that period always occurred due to pullout from the bone tunnel. The difference in mechanical properties between treated specimens and controls was significant by 8 weeks after surgery. Another technique of biological scaffolding to promote tendon graft healing within a bone tunnel consists of filling the gap between the tendon and the bone with a bone substitute. Tien et al50 performed an ACL reconstruction with semitendinosus tendon graft in a rabbit model and filled the gap between the tendon graft and the femoral bone tunnel with a paste of calcium-phosphate cement (CPC) obtained from mixing tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) powders. Histological examination showed that CPC produced early, diffuse, and massive bone ingrowth within the tunnel in comparison with control specimens. Mechanical testing showed that the mean maximal tensile strength for treated grafts was significantly greater than controls at 1 and 2 weeks after reconstruction.

CONCLUSIONS Several experimental studies have shown that bone–tendon graft healing in ACL reconstruction occurs in a period varying from 3 to 12 weeks. The quality and rate of healing depend on many variables, predominantly the type of graft. Soft tissue grafts such as hamstring tendon grafts heal within a bone tunnel by formation of a fibrous transitional layer between the tendon and bone, which contains

Graft-Tunnel Healing penetrating Sharpey-like fibers. This newly formed bone– tendon interface matures with time and resembles the indirect-type insertion observed in tendons and ligaments. Bone plug tendon grafts, such as patellar tendon, heal within bone tunnel by incorporation of the bone plug to the surrounding bone and formation of an indirect-type insertion at the interface between bone and the intraosseous fibrous portion of the graft. Bone–bone healing occurs more rapidly than tendon—bone healing. Resistance to pullout force appears to be similar between the two types of grafts by 8 to 12 weeks after surgery. Therefore soft tissue grafts need high primary fixation strength and stiffness because of the consistent risk of failure due to pullout from the tunnel during the first 2 months. Mechanical stresses can affect maturation and differentiation of the bone–tendon graft junction depending on many factors such as bone density, fixation, placement and tensioning of the graft, gap size, and postoperative immobilization. Compression of the graft within the tunnel can enhance healing for both the bone plug and soft tissue. However, during the first 3 months after an ACL reconstruction, regardless of the type of graft used, the strength of the bone–tendon graft junction does not influence the mechanical behavior of the femur–ACL graft–tibia complex because the weak link of the ligament replacement rapidly shifts from the fixation site to the midsubstance of the graft. Therefore the application of excessive loads during this period, such as a too-aggressive rehabilitation and early return to sport activities, may cause a permanent elongation of the graft, thus compromising the result of the reconstruction. Many efforts have been made to improve the quality and rate of bone–tendon healing. Tissue engineering and gene transfer techniques have been applied to obtain a direct-type fibrocartilaginous insertion of the ACL graft, similar to that of the native ligament, and to accelerate the healing process of tendon grafts within bone tunnel. However, more investigations will be necessary in the near future to evaluate the possible employment of these biological techniques in the clinical practice.

References 1. Pinczewski LA, Clingeleffer AJ, Otto DD, et al. Integration of hamstring tendon graft with bone in reconstruction of the anterior cruciate ligament. Arthroscopy 1997;13:641–643. 2. Petersen W, Laprell H. Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts. Knee Surg Sports Traumatol Arthrosc 2000;8:26–31. 3. Ishibashi Y, Toh S, Okamura Y, et al. Graft incorporation within the tibial bone tunnel after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:473–479. 4. Nebelung W, Becker R, Urbach D, et al. Histological findings of tendon-bone healing following anterior cruciate ligament reconstruction with hamstring grafts. Arch Orthop Trauma Surg 2003;123:158–163.

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5. Robert H, Es-Sayeh J, Heymann D, et al. Hamstring insertion site healing after anterior cruciate ligament reconstruction in patients with symptomatic hardware or repeat rupture: a histologic study in 12 patients. Arthroscopy 2003;19:948–954. 6. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 7. Grana WA, Egle DM, Mahnken R, et al. An analysis of autograft fixation after anterior cruciate ligament reconstruction in a rabbit model. Am J Sports Med 1994;22:344–351. 8. Blickenstaff KR, Grana WA, Egle D. Analysis of a semitendinosus autograft in a rabbit model. Am J Sports Med 1997;25:554–559. 9. Liu SH, Panossian V, Al-Shaikh R, et al. Morphology and matrix composition during early tendon to bone healing. Clin Orthop Relat Res 1997;339:253–260. 10. Schiavone Panni A, Milano G, Lucania L, et al. Graft healing after anterior cruciate ligament reconstruction in rabbits. Clin Orthop Relat Res 1997;343:203–212. 11. Goradia VK, Rochat MC, Grana WA, et al. Tendon-to-bone healing of a semitendinosus tendon autograft used for ACL reconstruction in a sheep model. Am J Knee Surg 2000;13:143–151. 12. Yoshiya S, Nagano M, Kurosaka M, et al. Graft healing in the bone tunnel in anterior cruciate ligament reconstruction. Clin Orthop Relat Res 2000;376:278–286. 13. Weiler A, Hoffmann RFG, Bail HJ, et al. Tendon healing in a bone tunnel. Part II: histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135. 14. Papageorgiou CD, Ma CB, Abramowith SD, et al. A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model. Am J Sports Med 2001;29:620–626. 15. Tomita F, Yasuda K, Mikami S, et al. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bonepatellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy 2001;17:461–476. 16. Weiler A, Peine R, Pashmineh-Azar A, et al. Tendon healing in a bone tunnel. Part I: biomechanical results after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:113–123. 17. Singhatat W, Lawhorn KW, Howell SM, et al. How four weeks of implantation affect the strength and stiffness of a tendon graft in a bone tunnel: a study of two fixation devices in an extraarticular model in ovine. Am J Sports Med 2002;30:506–513. 18. Milano G, Mulas PD, Sanna-Passino E, et al. Evaluation of bone plug and soft tissue anterior cruciate ligament graft fixation over time using transverse femoral fixation in a sheep model. Arthroscopy 2005;21:532–539. 19. Yamazaki S, Yasuda K, Tomita F, et al. The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of anterior cruciate ligament in dogs. Arthroscopy 2005;21:1034–1041. 20. Jackson DW, Grood ES, Goldstein JD, et al. A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model. Am J Sports Med 1993;21:176–185. 21. Kernwein GA. A study of tendon implantation into bone. Surg Gynecol Obstet 1942;75:794–796. 22. Whinston TB, Walmsley R. Some observation of reaction of bone and tendon after tunneling of bone and insertion of tendon. J Bone Joint Surg 1960;42B:337–386. 23. Forward AD, Cowan RJ. Tendon suture to bone: an experimental investigation in rabbit. J Bone Joint Surg 1963;45:807–823. 24. Park MJ, Lee MC, Seong SC. A comparative study of the healing of tendon autograft and tendon-bone autograft using patellar tendon in rabbits. Int Orthop 2001;25:35–39. 25. Shino K, Kawasaki T, Hirose H, et al. Replacement of the anterior cruciate ligament by an allogeneic tendon graft. An experimental study in the dog. J Bone Joint Surg 1984;66B:672–681.

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Anterior Cruciate Ligament Reconstruction 26. Harris NL, Indelicato PA, Bloomberg MS, et al. Radiographic and histologic analysis of the tibial tunnel after allograft anterior cruciate ligament reconstruction in goats. Am J Sports Med 2002;30:368–373. 27. Grassman SR, McDonald DB, Thornton GM, et al. Early healing processes of free tendon grafts within bone tunnels is bone-specific: a morphological study in a rabbit model. Knee 2002;9:21–26. 28. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 29. Tien YC, Chih HW, Cheng YM, et al. The influence of the gap size on the interfacial union between the bone and the tendon. Kaohsiung J Med Sci 1999;15:581–588. 30. Yamazaki S, Yasuda K, Tomita F, et al. The effect of graft-tunnel diameter disparity on intraosseous healing of the flexor tendon graft in anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:498–505. 31. Sakai H, Fukui N, Kawakami A, et al. Biological fixation of the graft within bone after anterior cruciate ligament reconstruction in rabbits: effects of the duration of postoperative immobilization. J Orthop Sci 2000;5:43–51. 32. Abramowitch SD, Papageorgiou CD, Withrow JD, et al. The effect of initial graft tension on the biomechanical properties of a healing ACL replacement graft: a study in goats. J Orthop Res 2003;21:708–715. 33. Yamakado K, Kitaoka K, Yamada H, et al. The influence of mechanical stress on graft healing in a bone tunnel. Arthroscopy 2002;18:82–90. 34. Yasko AW, Lane JM, Fellinger EJ, et al. The healing of segmental bone defects, induced by recombinant human bone morphogenetic protein (rhBMP-2). A radiographic, histological, and biomechanical study in rats. J Bone Joint Surg 1992;74A:659–670. 35. Des Rosiers EA, Yahia L, Rivard C-H. Proliferative and matrix synthesis response of canine anterior cruciate ligament fibroblasts submitted to combined growth factors. J Orthop Res 1996;14:200–208. 36. Jelic M, Pecina M, Haspl M, et al. Regeneration of articular chondral defects by osteogenic protein-1 (bone morphogenetic protein-7) in sheep. Growth Factors 2001;19:101–113. 37. Rodeo SA, Suzuki K, Deng XH, et al. Use of recombinant human bone morphogenetic protein-2 to enhance tendon healing in a bone tunnel. Am J Sports Med 1999;27:476–488.

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38. Anderson K, Seneviratne AM, Izawa K, et al. Augmentation of tendon healing in an intraarticular bone tunnel with use of a bone growth factor. Am J Sports Med 2001;29:689–698. 39. Mihelic R, Pecina M, Jelic M, et al. Bone morphogenetic protein-7 (osteogenic protein-1) promotes tendon graft integration in anterior cruciate ligament reconstruction in sheep. Am J Sports Med 2004;32:1619–1625. 40. Martinek V, Latterman C, Usas A, et al. Enhancement of tendonbone integration of anterior cruciate ligament grafts with bone morphogenetic protein-2 gene transfer: a histological and biomechanical study. J Bone Joint Surg 2002;84A:1123–1131. 41. Evans CH, Robbins PD. Possible orthopaedic applications of gene therapy. J Bone Joint Surg 1995;77A:1103–1114. 42. Deehan DJ, Cawston TE. The biology of integration of the anterior cruciate ligament. J Bone Joint Surg 2005;87B:889–895. 43. Demirag B, Sarisozen B, Ozer O, et al. Enhancement of tendon-bone healing of anterior cruciate ligament grafts by blockage of matrix metalloproteinases. J Bone Joint Surg 2005;87A:2401–2410. 44. Ouyang HW, Goh JC, Lee EH. Use of bone marrow stromal cells for tendon graft-to-bone healing: histological and immunohistochemical studies in a rabbit model. Am J Sports Med 2004;32:321–327. 45. Lim JK, Hui J, Li L, et al. Enhancement of tendon graft osteointegration using mesenchymal stem cells in a rabbit model of anterior cruciate ligament reconstruction. Arthroscopy 2004;20:899–910. 46. Ohtera K, Yamada Y, Aoki M, et al. Effects of periosteum wrapped around tendon in a bone tunnel: a biomechanical and histological study in rabbits. Crit Rev Biomed Eng 2000;28:115–118. 47. Chen C-H, Chen W-J, Shih C-H, et al. Enveloping the tendon graft with periosteum to enhance tendon-bone healing in a bone tunnel: a biomechanical and histologic study in rabbits. Arthroscopy 2003;19:290–296. 48. Kyung HS, Kim SY, Oh CW, et al. Tendon-to-bone tunnel healing in a rabbit model: the effect of periosteum augmentation at the tendon-tobone interface. Knee Surg Sports Traumatol Arthrosc 2003;11:9–15. 49. Youn I, Jones DG, Andrews PJ, et al. Periosteal augmentation of a tendon graft improves tendon healing in the bone tunnel. Clin Orthop Relat Res 2004;419:223–231. 50. Tien YC, Chih TT, Lin J-HC, et al. Augmentation of tendon-bone healing by the use of calcium-phosphate cement. J Bone Joint Surg 2004;86B:1072–1076.

PART L REVISION ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Revision Anterior Cruciate Ligament Reconstruction Using Autologous Hamstring Tendons INTRODUCTION Due to the high incidence of anterior cruciate ligament (ACL) ruptures and the tremendous socioeconomic importance of this injury, there continues to be intensive research into basic science, pathology, and reconstruction techniques of the ACL. Thus a wide range of techniques for ACL reconstruction and numerous different fixation devices are available. Nevertheless, the perfect technique for ACL reconstruction still seems to be elusive, demonstrated by the fact that primary ACL reconstruction is not successful in restoring normal knee kinematics in all cases. According to the current literature, revision surgery after primary ACL reconstruction is performed in 3% to 25% of cases due to long-term graft failure as well as unsatisfactory outcome (loss of range of motion, locking, effusion, pain, etc.).1–3 It is generally believed that revision ACL reconstruction is a challenging procedure requiring experience in a variety of different surgical techniques and graft fixation techniques. Revision ACL reconstruction might be even more demanding if surgical mistakes have been made during primary reconstruction, if a double-bundle reconstruction was performed, or if a severe tunnel enlargement has developed. Whether revision ACL reconstruction can be performed as a single- or two-staged procedure mainly depends on tunnel and hardware management.2,4,5 It has to be emphasized that the technique and the fixation devices selected for

ACL reconstruction should always easily allow for eventual later revision. However, unfortunately some techniques do not allow for an easy revision reconstruction, as demonstrated later. The goals of revision ACL reconstruction are similar to primary ACL reconstruction and include stabilization of the knee, prevention of further injury to articular cartilage and menisci, and recovery of knee function. It is generally believed that the overall clinical outcome after revision ACL reconstruction is inferior compared with primary procedures.2,5–13 Thus the importance of counseling the patient preoperatively about less satisfactory results than in primary ACL reconstruction must be emphasized. However, taking an inferior result into account, as described in the current literature, one might be quickly less optimistic about producing an optimal result after revision reconstruction. Therefore it should be our primary goal to be as perfect as possible with diagnostics and decision making as well as surgery in order to offer the patient a successful outcome, as in primary reconstruction. Thus we strongly recommend the use of a clearly defined diagnostic and treatment algorithm in order to fulfill that goal.

57 CHAPTER

Andreas Weiler Michael Wagner

FAILURE ANALYSIS Because of different surgical techniques, different graft types (including all kinds of autografts

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Anterior Cruciate Ligament Reconstruction and allografts as well as synthetic ligament substitutes), and different concomitant pathologies, the lack of homogeneity among patients is obvious. Real ACL rerupture caused by an adequate trauma can occur at any time after primary ACL reconstruction, even if perfect knee stability had been achieved. However, in our experience this is a quite rare situation. With careful analysis, in most cases specific issues can be found to be responsible for graft failure, such as the following: 1 Technical failures (e.g., tunnel malplacement [see later discussion]) 2 Inadequately addressed or unrecognized concomitant ligament pathology (see later discussion) 3 Graft selection (synthetics, allograft) 4 Biological issues (graft incorporation) 5 Inadequate rehabilitation The technique used for primary ACL reconstruction and the reasons that led to graft failure strongly influence the strategy and complexity of revision ACL reconstruction (e.g., hardware removal, choice of graft, fixation technique, additional surgery). Thus careful failure analysis and a thorough evaluation of actual boundary conditions have to be performed. This includes detailed history taking, especially regarding retrauma, instability, pain, swelling, and locking. The thorough clinical examination should address effusion, range of motion, menisci, knee stability (Lachman and pivot-shift test), and concomitant ligament pathologies (see later discussion).

Radiographic Evaluation Specific radiological assessments have to be performed to address tunnel placement, tunnel enlargement, type and location of hardware, degenerative changes, and posterior cruciate ligament (PCL) insufficiency. The performed radiographs should routinely include the following: 1 Lateral view in maximal extension or hyperextension (Fig. 57-1) a Localization of hardware and evaluation of tunnel placement in the sagittal plane (anterior placement of the tibial tunnel in relation to the Blumensaat line might result in anterior graft impingement14) b Evaluation of hyperextension (Fig. 57-2)

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FIG. 57-1 Lateral radiograph in maximal extension (orange line represents Blumensaat line) demonstrating an excessively anterior placement of the tibial tunnel. Sagittal hardware localization is easy to identify.

2 45-degree posterior anterior weight-bearing radiograph according to Rosenberg15 (Fig. 57-3) a Localization of hardware and evaluation of tunnel placement in the coronal plane b Evaluation of degenerative changes c Evaluation of notch configuration (Fig. 57-4) 3 Posterior stress radiographs of both knees16 (Fig. 57-5) a Exclusion of additional PCL insufficiency In cases with clinically apparent varus or valgus malalignment or posterolateral insufficiency, long standing radiographs should be made to assess the need for additional axis correction. In case of tunnel enlargement, a computed tomography (CT) scan is indicated to clearly analyze its dimensions (Fig. 57-6).

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FIG. 57-2 Clinical and radiological view of extensive hyperextension of a right knee. The orange line is the Blumensaat line demonstrating anterior impingement of the graft although the tibial tunnel (white line) is placed correctly, due to the hyperextension of the knee. Thus, in case of hyperextension, the need for a more posterior placement of the tibial tunnel as normally recommended has to be evaluated carefully.

FIG. 57-3 A 45-degree posteroanterior weight-bearing radiograph according to Rosenberg, indicating degenerative medial joint narrowing compared with the contralateral knee (arrow).

Concomitant Pathology The stabilizing functions of the single knee ligaments are not strictly separated. Secondary graft failure can often be found in combination with unrecognized concomitant ligament

pathology, even in perfect ACL reconstructed knees. In fact, all the knee restraints work as a unit and normal knee stability can only be achieved if all ligaments are intact. In cases of ACL insufficiency, secondary restraints such as the posterior oblique ligament (POL) and the posterior horn of the medial 429

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FIG. 57-4 A 45-degree posteroanterior weight-bearing radiograph according to Rosenberg, showing narrow notch configuration (so-called “gothic notch”).

FIG. 57-5 Posterior stress radiographs of both knees after anterior cruciate ligament (ACL) reconstruction of the right knee demonstrating unrecognized posterior cruciate ligament insufficiency of the right knee.

meniscus might compensate for the instability. However, if there is medial collateral ligament (MCL) insufficiency (especially POL) and/or a subtotal medial meniscus loss, the freshly reconstructed ACL might not be able to absorb the particular forces and might stretch out. In principle this can 430

be applied to any other combination of ligamentous knee injuries. Thus all directions of knee instability, especially rotatory instabilities, have to be assessed carefully during clinical (and radiological) examination. In detail these instabilities include the PCL (see Fig. 57-5), lateral or posterolateral

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FIG. 57-6 A and B, Conventional radiographs demonstrating tibial tunnel enlargement. C, Computed tomography (CT) scan performed to exactly assess the dimension of the tunnel enlargement.

FIG. 57-7 Posterolateral rotatory instability. A, Clinical view demonstrating increased external rotation of the right knee. B, Radiograph after posterolateral reconstruction, which in this case was not successful. C, Intraoperative view demonstrating severe posterolateral opening.

rotatory instability (PLRI; Fig. 57-7), anteromedial rotatory instability (AMRI), anterolateral rotatory instabilities (ALRI), and MCL or posteromedial rotatory instabilities (PMRI; Fig. 57-8). Now we have to question which of these concomitant pathologies needs to be addressed surgically in revision

procedures. If an AMRI or PMRI is present, a certain grade of instability might be left untreated in a revision case, as the influence of these instabilities is still not clearly defined and the outcome of surgery (MCL, POL, PMRI) often is unsatisfactory. If there is severe valgus opening, a posteromedial reefing (e.g., that according to Hughston) or 431

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+

A FIG. 57-8 Posteromedial rotatory instability. A, Schematic illustration demonstrating increased stress on the anterior cruciate ligament (ACL) in a case of medial instability. B, Intraoperative view demonstrating severe medial opening.

a ligament grafting could be done.17,18 Whether a microperforation of the medial structures according to Rosenberg is successful in these conditions needs further clinical research. In cases of lateral instabilities including PLRI and ALRI, the situation is different. In former years a grossly positive pivot shift was often treated by an additional anterolateral stabilization such as according to Lemaire19–21 (Fig. 57-9). At present, an additional extraarticular procedure is not routinely recommended; however, in revision reconstructions one might make an exception. In cases with only a slight anterior translation combined with a gross pivot shift, one might consider an additional anterolateral stabilization in selected cases if the femoral ACL graft position is lateral (10-o’clock position). If, for example, a revision reconstruction with lateral femoral tunnel placement does not restore the pivot shift during revision surgery, one might consider an additional Lemaire procedure in these rare cases. However, only one peripheral concomitant pathology should always be addressed during ACL revision reconstruction, the PLRI (see Fig. 57-7), because the high failure rate of ACL reconstruction in combination with a PLRI is well known.22–24 In principle, single-staged repair of any of these combinations is possible if boundary conditions allow for the planned surgical procedure. One major exception has to be assessed carefully, which is clinically apparent as the “fixed posterior subluxation.” Normally this phenomenon is discussed in the context of PCL insufficiency and repair. 432

However, it has been demonstrated that approximately 15% of all patients with PCL insufficiency underwent previous isolated ACL reconstruction.25 The reason for this failure often is a wrongly interpreted positive Lachman test, which in the case of PCL insufficiency and an intact ACL might demonstrate an increased way with a firm endpoint. Thus it is of great importance to always evaluate the PCL in ACL deficient knees. Additionally, the PCL deficient knee easily subluxates to posterior during ACL graft fixation, which might lead to a fixed posterior subluxation.26 This results in changed femorotibial biomechanics and high patellofemoral reaction forces. Patients who demonstrate a fixed posterior subluxation often suffer from very early and severe degenerative lesions. If a fixed posterior subluxation is diagnosed, the initial treatment includes the wear of a special brace (PTS Brace, Medi GmbH, Bayreuth, Germany), which pushes the tibia to anterior.25,26 Depending on boundary conditions and ligamentous instability, revision ACL reconstruction as well as PCL reconstruction might be indicated.26

HARDWARE MANAGEMENT Older fixation devices might compromise new tunnel creation and graft fixation. Therefore the type and localization of existing hardware have to be identified preoperatively. If metallic hardware was used, localization can be easily performed with plain radiographs in two planes. Even if biodegradable

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FIG. 57-9 Lateral extraarticular tenodesis using a strip of the iliotibial band in a case of anterolateral rotatory instability (Lemaire procedure).

fixation devices have been used, their localization can be approximated by conventional radiographs because in most cases old tunnels or sclerotic bone surrounding the old fixation devices can be seen even years after surgery.

Hardware Removal Hardware removal might result in distinct postoperative morbidity or large bone defects (e.g., transfixation devices or deeply countersunk metal interference screws) (Fig. 57-10). Thus older fixation devices need to be removed only if they compromise new tunnel placement or graft fixation. If metal fixation devices do not completely affect new tunnel placement, they often can be pushed into the cancellous bone by serial tunnel dilation (Fig. 57-11). Biodegradable interference screws, even if they are not degraded during revision surgery, do not need to be removed because they can easily be overdrilled. Only a careful washout of particles from the joint cavity is needed to prevent later chondral lesions and/or inflammatory response. Hardware removal also should be performed if older fixation devices clearly are responsible for local pain or discomfort (Fig. 57-12). Due to the variability of fixation devices available on the market, hardware removal can be extremely frustrating. Attempts to remove hardware using instruments that do not fit exactly to the fixation devices might result in large

bone defects and iatrogenic lesions. Thus in our experience a set of specially designed revision screwdrivers can be very helpful. These instruments fit to most of the fixation devices available (Fig. 57-13). Most of the standard metallic interference screws can be removed nicely in a single-staged procedure. However, if metal screws have been deeply countersunk (tibial site, femoral outside-in) and need to be removed for revision reconstruction, one might consider a two-staged procedure because the removal in these circumstances could be very time consuming. Moreover, if the removal of metal implants and ACL revision reconstruction are planned in the same procedure, the patient should be informed that it might be possible to end in a two-staged procedure if problems occur during implant removal. Sometimes problems occur during surgery; for example, if there is an incompletely incorrect tunnel (see later discussion) and the metal screw is large (9  25 mm), the additional removal of that screw might lead to a large bone defect, communicating with the old and desired new tunnel. In these cases, bone grafting in a two-staged procedure might be necessary. Sometimes the removal of metallic cross-pin devices, especially the Arthrex TransFix might be tricky, because the manufacturer recommends the countersinking of the implant (see Fig. 57-10). Based on our own experience, we always schedule patients with a metallic TransFix for a two-staged procedure. 433

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FIG. 57-10 Completely countersunk femoral transfixation device. Its removal necessitated an additional lateral approach and opening of the lateral femoral cortex.

TUNNEL MANAGEMENT Tunnel Malplacement

FIG. 57-11 Tibial metal screw that is pushed into the cancellous bone by serial tunnel dilation.

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One of the major keys to successful ACL reconstruction is a correct tunnel placement. Tunnel malplacement can lead to graft impingement, elongation, and failure; loss of range of motion; and high tibiofemoral contact forces. According to the current literature the femoral tunnel should be drilled in the 10-o’clock position for right knees or in the 2-o’clock position for left knees.27–29 This means that a lateral femoral tunnel position should be achieved in order to control rotation as well as anterior displacement of the knee. A femoral tunnel drilled at the 12-o’clock position (“high-noon” or central cruciate) might be appropriate to control anterior translation but does not allow for rotational stabilization.30,31 Often in these cases a normal Lachman test with firm endpoint combined with a positive pivot-shift test can be found in the clinical examination.

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FIG. 57-12 Hardware that needs to be removed due to local irritation or pain.

In addition to early chondral changes or graft failure, tunnel malplacement also leads to painful knees (femoral anterior placement) in many of these cases. If loss of range of motion and an intact (sometimes very tight) ACL are found in combination with tunnel malplacement, arthroscopic graft resection and arthrolysis have to be evaluated. If performed, these should be followed by intensive physiotherapy to regain full range of motion prior to ACL revision reconstruction.

Classification of Existing Tunnel Positions FIG. 57-13 A set of specially designed revision screwdrivers. (By permission of KarlStorz, Tuttlingen, Germany.)

Radiographically the tibial tunnel should be placed directly posterior to the intersection point of the Blumensaat line and the tibial joint line (lateral view in full knee extension) in order to avoid anterior impingement of the graft. Placement of the tibial tunnel too anteriorly might lead to an extension deficit due to notch impingement, which possibly results in long-term graft failure.14 Excessively anterior placed tibial tunnels can cause high-tension forces to the graft in knee flexion (“nutcracker knee”). In addition to graft elongation and secondary failure, this may lead to a flexion deficit and increased tibiofemoral pressure in flexion. These forces might result in early and massive chondral defects, even in young patients.

At our institution we established a classification of the position of formerly placed tunnels to aid in the specific planning of the revision procedure. Tunnel positions are diagnosed using conventional radiographs (lateral view in maximal extension, 45-degree posteroanterior weightbearing radiograph) and are graded as follows: 1 Correct (Fig. 57-14, A): The existing femoral or tibial tunnels are placed completely correctly and can be used again. 2 Completely incorrect (Fig. 57-14, B): The existing femoral or tibial tunnels are placed completely incorrectly, and a new tunnel can be created in the correct position without touching the old tunnel. 3 Incompletely incorrect (see Fig. 57-14, B): The existing femoral or tibial tunnels communicate with the new correctly placed tunnels, which might lead to large bone defects.

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FIG. 57-14 A, Completely correct femoral and tibial tunnels. B, Completely incorrect femoral and incompletely incorrect tibial tunnel. (White line represents the Blumensaat line.)

Surgical Management In general, the type of graft used during the index surgery should be known. If a bone–patellar tendon–bone (BPTB) graft was used, an incompletely incorrect tunnel at the femoral site might not create problems if the bone plug was not countersunk because a certain osseous fill-up of the defects is present. If a soft tissue graft was used during index surgery, an incompletely incorrect tunnel might offer the most challenging problem. Correctly positioned tunnels measuring less than approximately 8 mm in diameter can be reused if primary reconstruction was performed with a soft tissue graft, depending on the desired type of fixation (isolated versus hybrid). In these cases, tunnel preparation includes removal of intratunnel soft tissue using a drill or a shaver followed by drilling or dilation of the re-created tunnel to the desired diameter. The important effect of this procedure is a débridement of the tunnel wall by removing sclerotic bone so that graft incorporation can proceed (Fig. 57-15). In cases of complete incorrect tunnel placement or complete bony replacement of the previous graft (e.g., BPTB), new tunnel preparation can be done as in primary ACL reconstruction. If an old and completely incorrect tunnel shows excessive enlargement, it should be filled with a cancellous bone plug or, as an alternative, with a biodegradable interference screw prior to graft fixation to prevent collapse between the old and new tunnels (Fig. 57-16). 436

Surgically the most demanding cases are those with incompletely incorrectly placed tunnels. Drilling a correctly positioned tunnel in these cases might lead to huge bone defects. To achieve stable tunnel conditions, we suggest initially drilling a correctly placed tunnel with a diameter of only 4 to 5 mm and then using the serial dilation technique to the desired diameter. This procedure leads to a compaction of cancellous bone from the newly created tunnel into the old tunnel. In critical cases with very large bone defects or low bone density, a biodegradable interference screw or a cancellous bone plug can be placed into the old tunnel prior to dilation (Fig. 57-17). However, if there is any uncertainty, a two-staged procedure should be performed. Tunnel direction must be verified in the coronal plane in addition to the tunnel entry position. Because many surgeons use a transtibial technique for femoral tunnel creation, the direction of a new tunnel drilled via the anteromedial portal diverges from the old tunnel, which finally improves graft fixation even if the tunnel entry site is enlarged (Fig. 57-18). Thus the anteromedial portal technique should be recommended routinely in all ACL revision procedures. The importance of an intraoperative impingement test to evaluate tibial tunnel position must be emphasized. This test can be performed by placing the dilatator into the tibial tunnel. In full knee extension, the likelihood that anterior graft impingement will occur can be easily assessed. If excessive hyperextension was found in the clinical and radiological examination, the tibial tunnel should be placed more

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FIG. 57-15 Reuse of a completely correct femoral tunnel. Tunnel is cleaned by shaver and drill bit (A, B) followed by serial dilation (C, D).

FIG. 57-16 Completely incorrect femoral tunnel (shown with tunnel enlargement) is filled with a biodegradable interference screw prior to graft fixation to prevent collapse between the old (o) and new (n) tunnels.

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FIG. 57-17 Filling of an incompletely incorrect tunnel with a biodegradable interference screw prior to drilling and serial dilation of the new tunnel.

FIG. 57-18 Intraoperative and radiological views of femoral tunnel divergence. o, Old tunnel; n, new tunnel.

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Revision Anterior Cruciate Ligament Reconstruction Using Autologous Hamstring Tendons posterior than normally recommended to avoid notch impingement. In this situation the intraoperative impingement test should be performed very attentively.

3 Incomplete resection of the tibial ACL stump and graft placement in the center of the tibial stump (i.e., the old ACL stump covers the tunnel entry site)

Tunnel Enlargement

In contrast, the inflow of synovial fluid is advanced by the following:

Bone tunnel enlargement commonly occurs following an extracortical (nonanatomical) fixation technique combined with soft tissue grafts due to intratunnel graft motions or with BPTB grafts on the tibial site16,32 (windshield-wiper and bungee-cord effect) (Fig. 57-19). An additional biological factor that might lead to tunnel enlargement is inflow of synovial fluid between the tunnel wall and the graft during cyclical loading, which leads to high intratunnel pressures and the activation of osteoclasts by synovial cytokines. In these cases, radiographically the tunnel enlargement often appears pear–shaped below the joint line (see Fig. 57-19). The inflow of synovial fluid into the tunnel depends on the type of graft and its fixation. Factors that inhibit synovial inflow are as follows: 1 The use of grafts with bone blocks 2 Direct and anatomical fixation of any graft type

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1 Nonanatomical (extracortical) or semi-anatomical fixation of any graft 2 Imprecise graft–tunnel matching (loose grafts) 3 Complete resection of the tibial ACL stump If excessive tunnel enlargement can be seen on regular radiographs, a computed tomography (CT) scan is indicated to identify its exact dimensions. Based on CT findings of tunnel enlargement, the question of whether a two-staged procedure is necessary directly depends on the desired type of graft and fixation technique. If a two-staged procedure is indicated, the first step includes autologous or allogenic cancellous bone or bone substitute filling followed by revision ACL reconstruction. On the femoral site, the impaction of a cylindrical iliac crest graft or a cylindrical synthetic filler (b-tricalcium phosphate [TCP]) can be nicely performed arthroscopically (Fig. 57-20). The use of

FIG. 57-19 A, Lateral radiograph demonstrating femoral tunnel enlargement with semi-anatomical fixation device. B, Lateral radiograph demonstrating tibial pear-shaped tunnel enlargement, which might be due to inflow of synovial fluid.

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FIG. 57-20 Arthroscopic filling of an enlarged femoral tunnel with a cylindrical synthetic bone substitute (b-TCP).

bone chips on the femur might require special instruments if performed arthroscopically.16 On the tibial site one might use a single or two cylindrical plugs, which should be impacted. However, in most cases a tight filling with this technique is difficult. Thus we recommend using autologous bone chips, which are eventually mixed with synthetic materials (b-TCP) to tightly fill the old tunnel. In this case one should be careful not to compact bone chips into the joint cavity. We therefore recommend not to débride soft tissue from the tibial tunnel aperture site, which can later prevent bone chip access to the joint. A new CT scan before revision ACL reconstruction should be done to evaluate the exact bony recovery. If filling of the defects was successful, revision ACL reconstruction can be performed using the same methods as for primary reconstruction. The minimum time between bone grafting and revision reconstruction should be 3 months; 6 months is optimal.

GRAFT SELECTION AND FIXATION Graft Selection Similarly to primary ACL reconstruction, we have to differentiate grafts with bone blocks from soft tissue grafts and autografts from allografts. At present, the use of synthetic ligament substitutes is obsolete because of high failure rates and a high incidence of chronic knee inflammation. Due to a rising number of revision ACL reconstructions performed, the use of allografts is becoming more popular, especially in the United States. Advantages of allografts include reduced operative trauma (no donor site morbidity), decreased operation time, smaller incisions, and the available choices of graft sizes in multiple ligament reconstructions. One disadvantage is longer graft incorporation time compared with autografts. Thus, the 440

post-treatment needs to be adapted. The use of allografts with huge bone blocks might be helpful if huge tunnel enlargement is present. However, the risk of disease transmission must be considered and discussed with the patient. Hamstring tendons have become increasingly popular in ACL surgery due to decreased donor site morbidity, improved cosmesis, and at least identical clinical outcome compared with autologous BPTB grafts if modern fixation techniques are used.33 At our institution we routinely use hamstring tendon autografts (four-stranded semitendinosus tendon) for primary and revision ACL reconstruction if local boundary conditions (tunnel enlargement) allow for their use (see Fig. 39-3). In revision ACL reconstruction it might happen that the favored graft already has been harvested for primary ACL reconstruction. Thus if the use of an autograft is desired, it has to be decided whether another graft from the ipsilateral knee will be used or whether the graft will be harvested from the uninjured contralateral knee. If ipsilateral hamstrings were already taken for previous surgery, we routinely harvest the contralateral semitendinosus tendon. In cases when no hamstring tendons are left, we prefer autologous quadriceps tendon grafts rather than BPTB autografts or different allografts (e.g., hamstring tendon, BPTB, tibialis anterior tendon, Achilles tendon).

Graft Fixation The standard procedure in our institution for ACL revision reconstruction is a direct fixation technique by the use of biodegradable interference screws and hybrid fixation (Table 57-1) at both sites. General surgical principles of this technique, as well as possible intraoperative problems and their solution strategies, are described elsewhere in this text (see Chapter 46). The use of interference screws allows for an anatomical fixation at the level of the joint line, which has been shown to increase graft isometry34 and knee stability by

Revision Anterior Cruciate Ligament Reconstruction Using Autologous Hamstring Tendons

57

TABLE 57-1 Graft Fixation Technique Femoral Hybrid Fixation

 Interference screw and EndoPearl suture button and interference screw

 Suture button and cancellous bone plug  Transfixation and interference screw  Transfixation and cancellous bone plug Tibial Hybrid Fixation

 Interference screw and suture to bony bridge  Interference screw and suture button  Interference screw and staples  Cancellous bone plug and suture button  Cancellous bone plug and suture to bony bridge  Cancellous bone plug and tying of sutures over screw

reducing the graft length to its intraarticular portion, thus increasing construct stiffness.35,36 The use of interference fit fixation additionally reduces intratunnel graft motion, which is a common side effect of nonanatomical (extracortical) graft fixation. At present it is generally recommended to perform hybrid fixation at the tibial site, not only in revision but also in primary ACL reconstruction, for the following reasons: 1 The bone density of the proximal tibia is lower than that of the distal femur.

FIG. 57-21 Metallic and biodegradable interference screws are available in different sizes and diameters. Thus a precise matching of graft and tunnel diameter and screw size can be performed.

2 The direction of the tibial channel equals the direction of the forces that are applied to the ACL. In contrast, the direction of the femoral tunnel is angled to the intraarticular direction of the ACL. Thus graft slippage is more probable at the tibial site. An easy and secure method for tibial backup fixation is a suture of the linkage material over a bony bridge. To do so, a monocortical drill hole is created 2 cm distally of the tibial tunnel exit site. Then one strand of each attached suture is passed through the hole and tied over the created bony bridge37 (see Chapter 46). For femoral hybrid fixation with interference screw fixation, we prefer the use of a biodegradable spherical device (EndoPearl, Linvatec, Largo, FL). The EndoPearl is sutured to the femoral end of the graft and achieves an internal locking between the graft and the tip of the interference screw. Thus it increases fixation strength, especially in cases of tunnel enlargement and low bone density (see Chapter 39). Technical problems of graft fixation in revision ACL reconstruction often appear due to graft–tunnel mismatch,

FIG. 57-22 The use of two screws for tibial fixation in a case of tibial tunnel enlargement.

441

Anterior Cruciate Ligament Reconstruction especially in cases with completely correct or incompletely incorrect tunnel positions. The principles of tunnel placement depending on previously drilled tunnel positions were previously explained. If, after appropriate tunnel creation, the diameter of the femoral tunnel still is 1 to 3 mm larger than the graft diameter, femoral hybrid fixation with a biodegradable interference screw plus the EndoPearl device prevents graft slippage and allows for secure graft fixation (e.g., for a 9-mm tunnel and 7-mm graft, use a 9-mm EndoPearl and 8-mm interference screw). In cases with rather insecure tibial interference screw fixation, we favor the use of a suture button instead of the suture over a bony bridge. Manual rotation of the button tightens the linkage material, thus preventing graft slippage (see Chapter 46). Furthermore, in cases with impaired tibial bone quality, we suggest the use of oversized screws (diameter of 11–12 mm; Fig. 57-21) or the use of two screws (sandwich technique; Fig. 57-22) for tibial graft fixation.

References 1. Bach BR Jr. Revision anterior cruciate ligament surgery. Arthroscopy 2003;19:4–29. 2. Wirth CJ, Peters G. The dilemma with multiply reoperated knee instabilities. Knee Surg Sports Traumatol Arthrosc 1998;6:148–159. 3. Wolf RS, Lemak LJ. Revision anterior cruciate ligament reconstruction surgery. J South Orthop Assoc 2002;11:25–32. 4. Miller MD. Revision cruciate ligament surgery with retention of femoral interference screws. Arthroscopy 1998;14:111–114. 5. Noyes FR, Barber-Westin SD. Revision anterior cruciate surgery with use of bone-patellar tendon-bone autogenous grafts. J Bone Joint Surg 2001;83A:1131–1143. 6. Allen CR, Giffin JR, Harner CD. Revision anterior cruciate ligament reconstruction. Orthop Clin North Am 2003;34:79–98. 7. Brown CH Jr, Carson EW. Revision anterior cruciate ligament surgery. Clin Sports Med 1999;18:109–171. 8. Carson EW, Anisko EM, Restrepo C, et al. Revision anterior cruciate ligament reconstruction: etiology of failures and clinical results. J Knee Surg 2004;17:127–132. 9. Fules PJ, Madhav RT, Goddard RK, et al. Revision anterior cruciate ligament reconstruction using autografts with a polyester fixation device. Knee 2003;10:335–340. 10. Johnson DL, Swenson TM, Irrgang JJ, et al. Revision anterior cruciate ligament surgery: experience from Pittsburgh. Clin Orthop 1996;325:100–109. 11. Kohn D, Rupp S. [Strategies for interventional revisions in failed anterior cruciate ligament reconstruction]. Chirurg 2000;71:1055–1065. 12. Taggart TF, Kumar A, Bickerstaff DR. Revision anterior cruciate ligament reconstruction: a midterm patient assessment. Knee 2004;11:29–36. 13. Thomas NP, Kankate R, Wandless F, et al. Revision anterior cruciate ligament reconstruction using a 2-stage technique with bone grafting of the tibial tunnel. Am J Sports Med 2005;33:1701–1709. 14. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg 1993;75A:1044–1055. 15. Rosenberg TD, Paulos LE, Parker RD, et al. The forty-five-degree posteroanterior flexion weight-bearing radiograph of the knee. J Bone Joint Surg 1988;70A:1479–1483.

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16. Strobel M. Manual of arthroscopic surgery. Berlin, 2001, Springer-Verlag. 17. Fanelli GC, Orcutt DR, Edson CJ. The multiple-ligament injured knee: evaluation, treatment, and results. Arthroscopy 2005;21:471–486. 18. Hillard-Sembell D, Daniel DM, Stone ML, et al. Combined injuries of the anterior cruciate and medial collateral ligaments of the knee. Effect of treatment on stability and function of the joint. J Bone Joint Surg 1996;78A:169–176. 19. Christel P, Djian P. [Anterio-lateral extra-articular tenodesis of the knee using a short strip of fascia lata]. Rev Chir Orthop Reparatrice Appar Mot 2002;88:508–513. 20. Ireland J. LeMaire procedure for anterior cruciate instability. Injury 1999;30:151–152. 21. Lemaire M, Combelles F. [Plastic repair with fascia lata for old tears of the anterior cruciate ligament (author’s translation)]. Rev Chir Orthop Reparatrice Appar Mot 1980;66:523–525. 22. Gollehon D, Torzilli P, Warren R. The role of the posterolateral and cruciate ligaments in the stability of the human knee. J Bone Joint Surg 1987;69A:233–242. 23. Ishibashi Y, Tsuda E, Satoh H, et al. Posterolateral bundle reconstruction for rotatory instability after revision anterior cruciate ligament surgery. J Orthop Sci 2005;10:546–549. 24. Veltri D, Warren R. Operative treatment of posterolateral instability of the knee. Clin Sports Med 1994;13:615–627. 25. Strobel MJ, Weiler A, Schulz MS, et al. Fixed posterior subluxation in posterior cruciate ligament-deficient knees: diagnosis and treatment of a new clinical sign. Am J Sports Med 2002;30:32–38. 26. Weiler A, Jung T, Lubowicki A, et al. Management of posterior cruciate ligament reconstruction after previous isolated anterior cruciate ligament reconstruction. Arthroscopy 2007;23:164–169. 27. Hefzy M, Grood E, Noyes F. Factors affecting the region of most isometric femoral attachments. 17:208–216Am J Sports Med 1989;17:208–216. 28. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction. Comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304. 29. Sapega AA, Moyer RA, Schneck C, et al. Testing for isometry during reconstruction of the anterior cruciate ligament. Anatomical and biomechanical considerations. J Bone Joint Surg 1990;72A:259–267. 30. Arnold MP, Kooloos J, van Kampen A. Single-incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 31. Musahl V, Plakseychuk A, Vanscyoc A, et al. Varying femoral tunnels between the anatomical footprint and isometric positions. Am J Sports Med 2005;33:712–718. 32. Höher J, Möller H, Fu F. Bone tunnel enlargement after anterior cruciate ligament reconstruction: fact or fiction. Knee Surg Sports Traumatol Arthrosc 1998;6:231–240. 33. Wagner M, Kaab MJ, Schallock J, et al. Hamstring tendon versus patellar tendon anterior cruciate ligament reconstruction using biodegradable interference fit fixation: a prospective matched-group analysis. Am J Sports Med 2005;33:1327–1336. 34. Morgan CD, Kalmam VR, Grawl DM. Isometry testing for anterior cruciate ligament reconstruction revisited. Arthroscopy 1995;11:647–659. 35. Ishibashi Y, Rudy T, Livesay G, et al. The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system. Arthroscopy 1997;13:177–182. 36. Johnson D, Houle J, Almazan A. Comparison of intraoperative AP translation of two different modes of fixation of the grafts used in ACL reconstruction. Arthroscopy 1998;14:425. 37. Weiler A, Richter M, Schmidmaier G, et al. The EndoPearl device increases fixation strength and eliminates construct slippage of hamstring tendon grafts with interference screw fixation. Arthroscopy 2001;17:353–359.

Revision Anterior Cruciate Ligament Reconstruction* INTRODUCTION Reconstruction of the anterior cruciate ligament (ACL) has become an increasingly common orthopaedic procedure. In the United Kingdom, approximately 5000 ACL reconstructions are performed per year1; in the United States, more than 100,000 procedures are currently performed annually.2 This trend is likely to continue with the general population’s increasing pursuit of an active lifestyle. Although longterm functional stability and symptom relief after primary ACL reconstruction exceed 90% in some studies,3,4 overall clinical failure rates of 10% to 25% have been documented.1 It is currently estimated that between 3000 and 10,000 U.S. patients and approximately 1000 U.K. patients are candidates for revision ACL surgery annually.1 Revision ACL surgery is recommended for patients who have instability or reduced activity with pathological laxity after a failed primary ACL reconstruction. The important stages in assessing a patient with a failed ACL reconstruction include a detailed history, patient selection, physical examination and appropriate investigations, choice of graft, surgical technique, and rehabilitation.5 Eliciting important relevant history from a patient who is usually apprehensive and has some knowledge of the * The authors acknowledge the contributions and assistance of Dr. J. Ashken (ACL database design), Mrs. F. Wandless (Senior Physiotherapist), Mr. Niall Flynn (Consultant Orthopaedic Surgeon, Queen Alexandra Hospital, Portsmouth), and Mr. Raghu Kankate (Orthopaedic Surgeon).

problem (from general practitioners, physiotherapists, and the Internet) can be difficult. One should spend enough time trying to find out the details of the original injury (e.g., high-velocity trauma may suggest multiligament laxity) and also the patient’s experience of previous treatment as well as his or her knowledge of the problem. A full history of occupational and future recreational activities is mandatory. Often the patient’s expectations are not realistic, and therefore despite achieving knee stability, the revision surgery will not result in a contented patient. Instability and/or pain top the list of patient symptoms. It should be clarified with the patient preoperatively that a reduced activity level and/or excellent natural proprioception may result in a reduction or even an abolition in symptoms of instability without the need for surgery. Revision reconstruction should be offered to patients with symptoms of instability or those who wish to increase their activity level to include manoeuvres involving twisting or a sudden change in direction. In such cases symptoms of instability, if left untreated, will contribute to repeated meniscal and chondral damage, leading to an earlier progression of osteoarthritis (OA). At the same time, the patient should be made aware of the risk of a gradual progression of OA, irrespective of the method of treatment but especially if symptoms of instability are ignored. It should be carefully explained that symptoms of pain are likely to be caused by degenerative disease or a torn meniscus and that a revision ACL reconstruction alone is unlikely to be the answer to this problem. One should

58 CHAPTER

Neil P. Thomas Hemant G. Pandit

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Anterior Cruciate Ligament Reconstruction

FIG. 58-1 Failed anterior cruciate ligament (ACL) reconstruction. Anteroposterior (A) and lateral (B) views.

also alert the patient to the potential need for bone grafting and thus a staged reconstruction. The most useful investigations are the plain x-ray series of an anteroposterior (AP) standing radiograph and a lateral x-ray in full extension, together with skyline and Rosenberg views (Fig. 58-1).1 These will show the original tunnel placement and usually the fixation methods used, tunnel widening,6,7 osteolysis, and the presence and extent of joint space narrowing. If possible, comparison with previous radiographs will help quantify bone loss (tunnel widening). It is our practice to obtain a magnetic resonance imaging (MRI) scan preoperatively, but only rarely has this provided additional information that has changed the course of management. If no reason for the primary failure can be elicited, vigilance for a missed or complex laxity should be exercised. Careful clinical examination and an examination under anesthesia, which may include fluoroscopic stress views, are useful in finding an additional laxity.

CAUSES OF FAILURE OF PRIMARY PROCEDURE The causes of recurrent patholaxity after primary ACL reconstruction6–26 can be broadly divided into four groups: technical errors, failure due to biological factors, failure due to significant trauma, and failure owing to laxity in the secondary restraints.17 By far the most common cause 444

is error in the surgical technique, with 77% to 95% of all cases of ACL failure attributed to technical error.27 This category includes poor graft selection or harvest, improper tensioning or fixation, and especially incorrect tunnel placement.9,17,18 More than 70% of technical failures, and thus more than 50% of all ACL failures, can be attributed to malpositioned tunnels.8,17 Inappropriate positioning of either the tibial or the femoral tunnel results in excessive length changes in the graft as the knee moves through a range of motion, resulting in either a limited range of motion or excessive graft laxity.8,18 Anterior placement of the femoral tunnel, a common mistake, will result in limited flexion and potential graft failure if full flexion is achieved. Tibial tunnel placement may be somewhat more forgiving, but anterior placement leads to impingement in extension and excessive tension in flexion, whereas posterior placement may cause laxity in flexion.17 Perhaps the most common error in surgical technique involves the anterior placement of femoral and/or tibial tunnels.16 Carson et al recently published their review of 90 failed ACL reconstructions and quoted 52% of the failures as being due to surgical technical errors.28 Several studies have shown that a posterior and proximal placement of the intraarticular exit of the femoral tunnel is advisable and involves minimal lengthening of the ACL substitute toward extension.

TREATMENT OPTIONS Revision ACL surgery is often considered a salvage procedure with very limited goals, distinctly different from those of primary ACL reconstruction.5,29 Many reports in the literature quote inferior results for revision cases compared with primary reconstruction. However, with many categories of failure, the population of failed ACLs is a diverse group and a difficult subset to study.30 We ask the following questions before deciding on a definitive treatment plan:


Do we know why the primary graft has failed?
Have we obtained a full diagnosis?
Has the patient been fully counseled?
Will the patient cope with a change in plan brought about by unexpected findings during the examination under anesthesia (EUA) and arthroscopy, which might alter the time spent in rehabilitation?


Can the new graft be fully incorporated biologically within the widened bone tunnels? Unless the answers to all these questions are positive, we tend to favor a cautious two-stage approach. If revision ACL surgery is staged, then the first stage gives the surgeon

Revision Anterior Cruciate Ligament Reconstruction an added opportunity to assess the chondral and meniscal pathology and then give the patient a more realistic prognosis. It is also important to ascertain whether the tibial tunnel of primary surgery will interfere with the correctly placed revision tibial tunnel and the extent of loss of bone stock due to tunnel widening. In addition, one needs to determine whether the hardware needs to be removed and, if so, whether that will further contribute to the loss of bone stock. For the revision graft to function optimally, one needs to ensure that the tunnels are placed in an optimal position in a good-quality bone so that the fixation achieved will be as robust as the primary surgery. Management of previous tunnel malposition is technically demanding, and different surgeons have used various approaches for dealing with bony defects resulting from incorrectly positioned prior tunnels. In some cases of gross tunnel malposition, a new tunnel may simply be drilled without violating the original tunnel or removing any tunnel hardware. Alternatively, tunnels can be oriented in a divergent pathway that maintains the appropriate articular surface attachment. In many cases, however, new tunnels cannot be drilled without overlapping or breaking into a previous tunnel. Two or more screws can be used to supplement fixation and fill the cavity of an enlarged tunnel. Although this might be useful in limited cases, the fixation achieved tends to be inferior and postoperative rehabilitation may be compromised. Graduated tunnel dilators may allow controlled expansion of a previous tunnel, compacting rather than removing additional bone.17 In such instances, options include the use of an allograft tendon with an enlarged bony portion, an oversized interference screw, or stacked interference screws.31 If the original tunnel is correctly positioned and only slightly larger (3–5 mm) than the new graft, stacking two interference screws may be sufficient to fill the tunnel and secure the graft.32,33 Battaglia and Miller34 have described use of freeze-dried allograft bone dowels to address bony defects during revision ACL reconstruction. These allografts are readily available and can be easily used to fill deficiencies resulting from previous tunnels or osteolysis. The grafts provide sufficient structural support to allow redrilling of new tunnels through or next to the bone plug. Unfortunately this option implies slower graft incorporation35 and has implications for the rehabilitation regimen. Some authors have tried to stratify the treatment options by the extent of bony defect. For defects larger than 10 mm, they advocate the use of bone graft and a staged procedure. Although this stratification is useful, it has certain limitations. Accurate preoperative assessment of the tunnel size is difficult and unreliable with plain x-rays. CT is the most accurate method.

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After clearing the debris from the earlier drilled tunnel, the resultant defect is almost always larger than 10 mm. Therefore we usually favor a staged reconstruction as a default technique. The first stage involves an EUA, an assessment of chondral and meniscal pathology, the removal of old graft, tunnel curettage, drilling, and bone grafting. The second stage is revision ACL reconstruction after incorporation of bone graft, 3 to 6 months after the first stage, when a CT scan has shown adequate incorporation of the bone graft.

DEFINITION OF KNEE INSTABILITY The IKDC classifies knees that are within 2 mm of the normal contralateral knee by means of KT-1000 or similar testing as “normal.”36 Knees that have greater than 5 mm of difference are classified as “abnormal.” The KT-1000 applies a force of 134N to assess knee laxity. For the past 15 years, we have used the Westminster cruciometer (University College, London) for laxity measurements. It is a validated tool that applies an 89N force during the laxity measurement. Similar to the KT-1000, this cruciometer has been shown to give a reproducible quantitative evaluation of the Lachman test, and a previous study has shown average displacement of normal knee to be 3.2 mm as compared with 8.4 mm in the ACL deficient knee.37 A further validation of the Westminster cruciometer was done recently by comparing the laxity measurements in normal, ACL deficient, and ACL reconstructed knees. The correlation between the Westminster cruciometer and KT-2000 was found to be excellent (Pearson’s coefficient: 97%). The KT-2000 reading can be obtained using the following equation: KT  2000 value ¼ 0:845  Westminster reading  0:5904ð61Þ

Since the original recommendations by the IKDC, various published results have used slightly different criteria in defining knee stability. In addition to instrumented laxity measurements, the clinically relevant pivot-shift test is widely used. The pivot-shift test has various grades, and one needs to be clear in reporting the grade (1þ, glide; 2þ, clunk; 3þ, subluxation) that is being considered as abnormal. In our practice using the Westminster cruciometer (applying a force of 89N rather than 134N) to assess the knees, we use the following criteria to define normal laxity: The side-to-side difference (SSD) in anterior tibial translation is considered normal if within 2 mm and nearly normal if between 3 and 4 mm. Values of 5 mm and greater are considered unsatisfactory. Overall anterior laxity is considered satisfactory if the SSD is less than 5 mm and the pivot shift is absent or 1þ (glide). 445

Anterior Cruciate Ligament Reconstruction In the presence of an SSD greater than 4 mm and/or a pivot shift of 2þ (clunk) or 3þ (subluxation), the anterior laxity is considered unsatisfactory.

SURGICAL PROCEDURE Stage I Stage I includes an EUA and arthroscopy, assessment and appropriate treatment of meniscal and chondral pathology, removal of the previous graft, notch assessment, and notchplasty when necessary. Although we have not encountered infection in this series, a high index of suspicion should always be maintained, and we routinely send multiple synovial biopsies in each case. Interfering metal work is removed, and the tibial tunnel is bone grafted with bone graft taken from the patient’s ipsilateral iliac crest. The meniscal and chondral structures are assessed and carefully documented. The menisci commonly show evidence of degeneration, and their tears are complex. These tears are usually in the white-white zone, necessitating partial meniscectomy rather than meniscal suture. Articular cartilage assessment invariably reveals more changes than were previously suggested on a plain weight-bearing radiograph and the MRI scan. The changes in the articular cartilage are documented with regard to depth, size, and position. The appearance of the articular cartilage is recorded as abnormal if the lesion is 15 mm or more in diameter with fissuring and fragmentation of more than half its depth or if any subchondral bone was exposed. Loose chondral flaps are removed, and their edges are débrided back to stability. The finding of exposed bone is not a contraindication to revision ACL surgery. Such lesions are dealt with using a marrow stimulating technique, namely drilling and/or microfracture. If a patient has persistent pain after a failed microfracture, then leg alignment views are requested and treatment such as osteotomy combined with autologous chondrocyte implantation should be considered. The intercondylar notch is usually full of scar tissue, which includes the previously reconstructed incompetent ACL. Removing the previous ACL autograft using a combination of hand and powered tools is relatively straightforward. However, clearance of prosthetic graft can be time consuming due to the tougher nature of the material. In cases in which an over-the-top position was used for the femoral tunnel placement at the time of primary reconstruction, a large “wadge” of lax, swollen graft can be seen exiting the joint superolaterally. In all cases, one needs to exercise extreme care to identify the margin and then the entire posterior cruciate ligament (PCL) so that the safe removal of all other structures in the notch can be safely performed. 446

If the new tunnel placement is possible without interference from previous hardware, the hardware can be left in place. However, if the desired position of the new tunnel(s) intersects or overlaps (either partially or fully) the previous tunnels, the metalwork should be removed carefully after ensuring that the screw head is free of all soft tissue and that the screwdriver is fully seated. If the tibial tunnel is interfering with the placement of the new tibial tunnel (in the correct anatomical position), then following the initial procedure, the tunnel is viewed with the arthroscope in air medium (osteoscopy). The sclerotic walls of the tunnel are drilled with a fine 2-mm drill, and the tunnel is curetted and rasped until the tunnel walls are taken back to clean bone. Bone in the form of dowel grafts is harvested from the iliac crest, placed into the tibial tunnel, and then impacted. If there is insufficient autologous bone, then this can be supplemented with human bone (either from a bone bank or a proprietary human bone). It is important to impact the bone. Care is taken not the breach the exit point of the tibial tunnel within the joint. This is achieved by viewing the relevant articular surface of the tibial plateau with the arthroscope as the bone graft is being impacted up the tunnel. We have chosen not to graft the femoral tunnel but merely alter the technique. However, if the surgeon finds that he or she will not be able to make a satisfactory new tunnel, then the existing femoral tunnel can be bone grafted (similar to tibial tunnel) so as to ensure good bone quality for the second-stage surgery. A CT scan obtained after 4 to 6 months is useful to assess healing of the bone graft (or its dissolution) in the tibial tunnel. Blurring of the tunnel margins, reactive sclerosis, and presence of bone within the tunnel are used as signs of adequate healing.

Stage II The second stage includes a further EUA, arthroscopy, relevant meniscal and chondral surgery, graft harvest, and revision ACL reconstruction. Our choice of graft is described in Table 58-1.

TABLE 58-1 Choice of Graft for Revision Surgery Primary Graft

Revision Graft

Bone–patellar tendon–bone

Four-strand hamstring

(BPTB) Four-strand hamstring

BPTB

Prosthetic

Ipsilateral BPTB graft or four-strand hamstring

Revision Anterior Cruciate Ligament Reconstruction The revision procedure itself is similar to any primary procedure, and attention is given to achieve the correct anatomical placement of the tunnels. Because the landmarks are often less distinct than in a primary case, the tibial tunnel should be referenced off the PCL on the medial side of the mid-intercondylar point and the femoral tunnel referenced from the over-the-top position. We have favored the use of proprietary jigs (femoral Puddu guide, Acufex). Perioperative imaging using an image intensifier may occasionally be necessary to ensure optimal tunnel placement (Fig. 58-2). The correctly placed revision tibial tunnel is drilled. For the femoral tunnel, the technique used at the time of revision surgery is different than that used at the time of primary surgery. If an inside-out technique was used during the primary reconstruction, the femoral tunnel is drilled from outside-in (and vice versa) to ensure the new revision tunnel placement in virgin bone.

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GRAFT CHOICE: AUTOGRAFT VERSUS ALLOGRAFT For a long time it has been debated whether an autograft or an allograft should be used for revision ACL reconstruction.38–41 Allografts have certain advantages. The donor site morbidity is eliminated, which may help during the rehabilitation. When weighed against the total costs of a two-staged ACL reconstruction, their use could be financially justified. However, they do have specific risks. Viral transmission of hepatitis, human immunodeficiency (HIV) virus, or other infection is a concern.42 Allografts tend to integrate more slowly than autografts and can cause immunological reactions, which may interfere with the healing process; hence the recommendation of a slower rehabilitation protocol.41 Furthermore, the sterilization process used may decrease the mechanical properties of the allograft. In addition, this increases the cost. As of March 11, 2002, the Centers for

FIG. 58-2 Radiographs after second-stage revision. Anteroposterior (A) and lateral (B) views.

447

Anterior Cruciate Ligament Reconstruction Disease Control and Prevention (CDC) had received 26 reports of bacterial infections from musculoskeletal allografts.43 Because the notification of infection secondary to use of allografts is voluntary, it is likely that its true incidence is underestimated. We agree with the concept that every effort should be made to ensure killing of bacteria and bacterial spores with the help of available technologies. These added risks of using an allograft have led us to refrain from their routine use. An allograft should only be considered when host material is scarce. This is sometimes the case in patients with multi-ligament laxity. One can use ipsilateral and contralateral bone–patellar tendon–bone (BPTB) as well as hamstring tendons but may still have to use allografts for a multidirectional laxity involving the ACL, PCL, posterolateral corner (PLC), and/or medial collateral ligament (MCL).44–46 We have always favored the use of autograft rather than allograft. It is not our practice routinely to use the contralateral limb for harvesting the graft, although some surgeons prefer the contralateral limb in the primary or revision setting.46 We do not have any experience of using reharvested BPTB or four-strand hamstring (4-SH) graft; reports in the literature of their use and satisfactory clinical outcome are few.47

GRAFT FIXATION: CORTICAL OR APERTURAL The techniques for graft fixation during the revision procedure are similar to those used in the primary procedure. When dealing with bone–bone fixation, the interference screw,48 is our traditional method of fixation, although if the femoral tunnel is a tight fit, Rigidfix (Mitek Products, Ethicon, Edinburgh) is satisfactory. For hamstring fixation, we use IntraFix (Mitek) on the tibial side; for a cortical fixation on the femoral side, a Corin anchor (Corin Group, The Corinium Centre, Cirencester, United Kingdom) is used. The types of fixation method used on both the femoral and tibial sides play a crucial role in the stability achieved after ACL reconstruction. The fixation devices must be able to withstand early postoperative forces until graft–tunnel healing has occurred. The fixation should facilitate graft tunnel healing, producing a normal histological transition zone between the host bone and the new ligament.45,49 The fixation methods can be broadly classified as cortical (suspensory) or apertural (intratunnel).50 There is a belief that cortical fixation may not perform as well as aperture fixation and that there may be a “bungee effect” causing reduced stability because fixation is farther from the joint, resulting in a longer graft with reduced stiffness. Cyclical elastic stretching under loading can be expected to increase with lengthening of the graft between the points of fixation. Anchoring the graft distant to the joint line may also allow AP movement, described as a “windshield wiper” effect after 448

widening of the tunnel. However, this is debatable. Graft fixation relies on the friction between the graft and the fixation device until the graft integrates with the surrounding host tissues.50 Older methods such as in-line staples (tibial side) or simple buttons (femoral side) have a high chance of graft slippage due to their dependence on “simple friction” between the fixation device and a smooth, compressible soft tissue graft. This prevents the grafts being satisfactorily tightened and held. On the other hand, techniques such as Endobutton (Smith & Nephew, Andover, MA), Corin Anchor, and newer tibial devices rely on “complex friction” and thereby ensure better stability.51–56 Prodromos et al,50 in a recent meta-analysis of ACL reconstruction, considered stability after ACL reconstruction as a function of hamstring versus patellar tendon graft and fixation type. The authors concluded that four-strand hamstrings had overall higher stability than BPTB and the graft stability was fixation dependent. Four-strand hamstring grafts with Endobutton femoral fixation and second-generation tibial cortical fixation (belt-buckle staple configuration or interference screws augmented with staples) resulted in higher stability than all other graft/fixation combinations. Therefore either the bungee effect does not exist or, if it does exist, it seems inconsequential. Also, it is likely that the bungee effect is only likely during the early postoperative period before the bone tunnels have healed around the graft, converting cortical to apertural fixation.50 Different authors have assessed34,49,57–60 the fixation strengths of various femoral and tibial fixation devices used for ACL reconstruction. Harvey et al in their succinct review article considered the different types of fixations used along with results of laboratory testing.49 These are summarized in Tables 58–2, 58–3, and 58–4.49 Tibial fixation is commonly considered more problematic than femoral fixation because forces on the ACL substitute are parallel to the tibial drill hole,60,61 the bone quality of the tibial metaphysis is inferior to that of the femur,61,62 and the four-tailed end of the hamstring tendon graft that is fixed to the tibia is more difficult to secure. The WasherLoc secures the graft at the external tibial aperture, and the tandem spiked washers have an even longer working length because they are placed completely outside the tibial tunnel. The IntraFix may be considered a semiaperture fixation because the 30-mm plastic sheath extrudes distally from the entrance of the tibial drill hole and thus, in a normal tibial tunnel of 35 to 45 mm in length, leaves 5 to 15 mm of free graft within the proximal opening (aperture) of the drill hole. Finally, interference screws can be considered truly anatomical (apertural) fixations because they can be advanced to the internal tibial tunnel orifice. When interference screws are used in the tibia, they are inserted from the outside-in, producing forces that are

Revision Anterior Cruciate Ligament Reconstruction

58

TABLE 58-2 Bone–Patellar Tendon–Bone (BPTB) Fixation Options Authors

BPTB Fixation

Johnson

Stainless steel interference

and van

screw (9 mm)

Specimen Test

Human

Femoral bone cortext

ULF

Stiffness

Cyclical

(N)

(N/mm)

Testing

436

—

N/A

removed. Force in line of

Dyk

Mode of Failure

Tendon and cortical bone graft pulled out of femur

tunnel Biodegradable interference

Human

screw (9 mm)

Femoral bone cortex

565

—

N/A

removed. Force in line of

Failure between cortical and cancellous bone of the graft

tunnel Steiner

Interference screw (9 

et al

25 mm, outside-in

interference screws, usually on

technique)

tibial side

Interference screw (7 

Human

Human

Femur–tibia complex

423

45

N/A

Femur–tibia complex

588

33

N/A

Femur

552.5 —

N/A

Bone plug slippage past

25 mm, endoscopic technique) Caborn

Interference screw: Bioscrew Human

et al

(7  25 mm) Titanium alloy interference

Human

Tensile load 20 mm/min

558

—

N/A

screw (7  25 mm) Yamanaka

Suture post

Suture tied over buttons

Fracture tibial bone block– ligament bone separation

Porcine

Femur–tibia complex

851

23.5

et al Kurosaka

Femoral fixation–ligament bone separation

Human

Tibia/femur not specified

248.2 12.8

5000 cycles Bone plug breakage or thread ULF: 754N

rupture

N/A

Avulsion fracture at tendon

et al

insertion Staple

Human

Tibia/femur not specified

128.5 10.8

N/A

AO 6.5-mm screw

Human

Tibia/femur not specified

214.8 23.5

N/A

Porcine

Tibia: vertical tensile load

785

Ruop et al Titanium interference screw

—

N/A

(7  25 mm) Biodegradable interference

Porcine

Tibia: vertical tensile load

555

—

N/A

screw (PGA 7  25 mm) Biodegradable interference

Bone block pulled out in most cases

Porcine

Tibia: vertical tensile load

592

—

N/A

screw (PLA 7  23 mm) Ruop et al Press-fit fixation

Bone block pulled out in most cases

Bone block pulled out in most cases

Porcine

Tibia: vertical tensile load

462.5 —

N/A

Pullout of complete bone plug in most cases

Titanium interference screw

Porcine

Tibia: vertical tensile load

768.6 —

N/A

Porcine

Tibia: vertical tensile load

805.2 —

N/A

(9  25 mm) Biodegradable screw (7  23 mm)

most cases

Gerich

2 staples with bone block in Human

Tibia: force in line with

et al

tibial groove

tibial axis

Novak

Krackow suture #5 Ticron

et al

over screw and post Screw and free bone block

Pullout of complete bone plug in

588

86

N/A

Slippage of bone block in tibial groove

Bovine

Tibia

374

24

N/A

Bovine

Tibia

669

90

N/A

—

(9  20 mm) (continued)

449

Anterior Cruciate Ligament Reconstruction TABLE 58-2 Bone–Patellar Tendon–Bone (BPTB) Fixation Options—Cont’d Authors

Matthews et al

BPTB Fixation

Specimen Test

ULF

Stiffness

Cyclical

(N)

(N/mm)

Testing

Interference screw

Porcine

Tibia

435

—

N/A

#2 nonabsorbable sutures

Porcine

Tibia

454.2 —

N/A

Porcine

Tibia

415.8 —

N/A

Mode of Failure

—

tied over screw and washer #5 nonabsorbable suture ULF, Ultimate load to failure. Caborn et al. Arthroscopy 1997(13):229–232; Gerich et al. Knee Surg Sports Traumatol Arthrosc 1997(5):84–88; Johnson et al. Arthroscopy 1996(12):452–456; Kurosaka et al. Am J Sports Med 1987(15):225–229; Matthews et al. Arthroscopy 1993(9):76–81; Novak et al. Arthroscopy 1996(12):160–164; Rupp et al. Arthroscopy 1997(13):61–65; Rupp et al. J Biomed Mater Res 1999(48):70–74; Steiner et al. Am J Sports Med 1994(22):240–246. Yamanaka et al. Am J Sports Med 1999(27):772–777.

TABLE 58-3 Hamstring Femoral Graft Fixation Options Authors Hamstring Femoral Fixation

Specimen Test Protocol

ULF (N)

Stiffness

Cyclical Testing

Mode of Failure

1500N: 300 cycles 5.7 mm

Tendon

elongation 450N: failure

shredded by

(N/mm) Ciurea

Clawed washer and screw

Bovine

et al

Femur: pull in line

502

—

of bone tunnel– bovine exts tendons Interference screws (soft)

Bovine

(titanium) 7, 8, 9 mm  25 mm

Femur: pull in line

591 (8 

150N: 1 to 3 mm slippage

Slippage of

of bone tunnel

25 mm

by 1100 cycles 450N:

tendon past

screw)

specimen failed 1100 cycles screws

screws Tunnel 7, 8, 9 8, 9, 10 mm Interference screw (round

Bovine

headed) 25 mm  8 mm screw

teeth of washer —

Femur: pull in line

445 (8 

150N: 6.8 mm slippage by

Cutting and

of bone tunnel

25 mm

1100 cycles 450N:

slippage of

screw)

specimen failed

tendon past

9 mm tunnel

—

screw Caborn

Interference screws RCI screw

et al

(7 mm)

Human

Femur

242

—

—

Graft pulled out around screw 13/ 16 specimens

Bioabsorbable (7 mm) Bioscrew

Human

Femur

341

—

—

Graft and screw pulled out from femoral tunnel 3/16

Kousa

Endobutton-CL

et al

Porcine

Femur: force along

1086781

axis drill hole

after

—

1500 load cycles (50–200N)

cyclical loading Bone mulch screw

1112925

—

after cyclical loading Bioscrew

589565

—

after (continued)

450

Revision Anterior Cruciate Ligament Reconstruction

58

TABLE 58-3 Hamstring Femoral Graft Fixation Options—Cont’d Authors Hamstring Femoral Fixation

Specimen Test Protocol

ULF (N)

Stiffness

Cyclical Testing

Mode of Failure

N/A

Graft rupture of

(N/mm) cyclical loading RCL screw

546534

—

after cyclical loading Rigidfix

868768

—

after cyclical loading Clark

Cross-pin (2.5 mm diameter)

et al

35 mm

Porcine

Femora 2.5 mm/sec 1003

—

to failure

slippage from grip

70 mm To et al

Endobutton

Human

Femora

1604

—

N/A

430

23

N/A

Failure of suture loop knot

Mitek anchor

Human

Pull in line of tunnel 312

25

N/A

Distal migration of the anchor in the bone tunnel

Cross-pin (post–bone graft)

Human

1126

225

N/A

Bending or fracture of the pin

ULF, Ultimate load to failure. Caborn et al. Arthroscopy 1998(14):241–245; Clark et al. Arthroscopy 1998(14):258–267; Giurea et al. Am J Sports Med 1999(27):621–625; Kousa et al. Am J Sports Med 2003 (31):174–181; To et al. Arthroscopy 1999(15):379–387.

counter to the direction of the tension on the graft, as opposed to the femoral side, where the screw is placed from the inside-out, thus wedging the graft during screw insertion. The strength of fixation of interference screws is influenced by several variables, such as the density of the bone,61 the insertion torque,63 the geometry55,64,65 and material of the screw,66 and the length and diameter of the screw.67 Different considerations may be important in the fixation of hamstring and BPTB grafts. Increasing the diameter of the screw increases the fixation of the hamstring by a press-fit mechanism that crushes the surrounding cancellous bone. However, poor engagement of the thread into the tendon may make this less important and length of the screw more so. Engagement of the thread into a corticocancellous BPTB block gives good fixation, which is influenced more by the changes in the diameter of the screw and less so by changes in the length (Fig. 58–3).49

POSTOPERATIVE REHABILITATION All patients start knee flexion on the first day after surgery, and resting with the heel supported is encouraged to achieve full hyperextension. Patients are encouraged to perform static quadriceps exercises to prevent a quadriceps lag, and ice therapy is used regularly to ensure an early reduction in swelling. The patients are mobilized on the first or second day after surgery with elbow crutches, which are used until a good gait pattern has been achieved. The regimen is continued at home with emphasis in the first 2 weeks on achieving full hyperextension, flexion past 90 degrees, a reduction in swelling using ice elevation, rest, non–weightbearing exercises, and minimal walking. The rehabilitation program is continued as an outpatient with a series of graduated mobilizing, strengthening (isometric, closed chain, and [later] some open chain), and dynamic stability 451

Anterior Cruciate Ligament Reconstruction TABLE 58-4 Hamstring Tibia Graft Fixation Options Authors

Hamstring Tibia

Specimen

Test Protocol

ULF (N)

Stiffness

Cyclical Testing (mm)

Mode of Failure

(N/mm) Magno

Animal/human

Pull in line of tibial

50N increments slippage

et al

not specified

tunnel

(mm) at 250N(a), 500N(b)

WasherLoc

821*

200

(a) 0.23(b) 0.81

—

Tandem washers

1375

248

(a) 0.49(b) 1.23

—

Sutures/posts (#5

830

259

(a) 1.67(b) 4.87

—

Staples

705

60

(a) 1.01(b) 3.31

—

Interference

776

118

(a) 0.25(b) 0.72

—

930

225126

(a) 1.12(b) 3.52

—

898

—

150N elongation 2.1 mm

—

Ethibond)

screw (9  25 mm) Spiked 20-mm washer Giurea

Stirrup

Bovine

et al

Tibia: pull in line of tunnel

Nagarkuiti

Bioabsorbable

et al

screw

Porcine

Tibia

450N intact 408

69

Anatomical graft

0–150N 5000 cycles

2 of 5 failures

1.3 mm displacement

before 5000

placement: vertical

cycles

load Kousa et al WasherLoc

Porcine

Tibia: load applied

9751917 after

along drillhole axis

cyclical loading

Spiked washers

759675

IntraFix

13321309

Bioscrew

512567

Coleridge

Bovine

1500 cycles 50–200N

1000 cycles 70–22N

and Amis

slippage (mm) RCL

Tibia: pull in line of

491

1.3

Delta screw

641

1.15

IntraFix

543

0.69

Bicortical screws

770

1.17

WasherLoc

945

0.88

tunnel

ULF, Ultimate load to failure. Coleridge et al. Knee Surg Sports Traumatol Arthrosc 2004(12):391–397; Giurea et al. Am J Sports Med 1999(27):621–625; Kousa et al. Am J Sports Med 2003(31):182–188; Magen et al. Am J Sports Med 1999(27):35–43; Nagarkatti et al. Am J Sports Med 2001(29):67–71. *Yield loads.

exercises. Running is started from 10 weeks or when a “quiet” knee (i.e., minimal pain and swelling) has been achieved. Rehabilitation programs are individually tailored to include sports-specific training, and patients can return to contact sports from 6 months. Patients with meniscal or 452

chondral deficiency may be advised to avoid high-impact training and activities. Brown and Carson2 suggested that an accelerated rehabilitation program68 for revision ACL reconstruction is not appropriate due to weaker initial graft fixation. We

Revision Anterior Cruciate Ligament Reconstruction

FIG. 58-3 Scan of a failed anterior cruciate ligament (ACL) reconstruction demonstrating a huge tibial defect.

have found that this is not necessary, as using a two-stage technique ensures that there is good quality bone around the tunnels and initial graft fixation is as secure as in the primary reconstruction. We have followed the same rehabilitation program for both primary and revision ACL patients and have not found any significant difference between the objective and subjective laxity assessment at follow-up between the primary and revision ACL reconstruction.

OUR EXPERIENCE WITH A TWO-STAGE REVISION ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION From 1991 to 2003 the senior author performed 75 revision ACL reconstructions. Of these, nine were performed as a single-stage revision, and 11 were performed in patients with multi-ligamentous laxity needing attention. The remaining 55 patients underwent revision ACL reconstruction using a two-stage technique with bone grafting of the tibial tunnel (Fig. 58-4). Of these 55 patients, 49 had a minimum follow-up of 3 years or more, and we compared this group of patients with a matched cohort of 49 patients with primary ACL reconstruction. These results were recently published in the American Journal of Sports Medicine.1 The salient findings of this study are summarized here. The average age of the patients at the time of revision ACL reconstruction was 35.4 years (range 26–42 years). None of the patients was lost to follow-up in this study. The mean follow-up was 6 years (range 3–11 years). Preoperatively, all knees had positive Lachman and pivot-shift tests. The pivot shift was graded 1þ (glide) in four knees,

58

FIG. 58-4 Scan of the proximal tibia 6 months after bone grafting the tibial tunnel.

2þ (clunk) in 34 knees, and 3þ (subluxation) in 11 knees. This improved to pivot-shift grades of 0 in 43 knees, 1þ in five knees, and 2þ (clunk) in one knee. The mean laxity measurement (SSD) using Westminster cruciometer was 1.36 mm (standard deviation [SD]: 1.11), and this was not significantly different from the primary reconstructions (mean 1.2 mm; SD: 1.5). In one patient from the revision ACL group, the graft stretched out (the patient suffers from generalized ligamentous laxity) 4 years after the revision surgery, and the patient is awaiting rerevision surgery. Technical error was the most common reason for graft failure (femoral, 28 cases; tibial, 20 cases; both femoral and tibial, four cases). Tunnel enlargement was seen in all the cases. The mean tibial tunnel measurements were 13.7 mm (SD: 2.5 mm) on AP and 13.9 mm (SD: 2.3 mm) on lateral radiographs. The mean IKDC subjective and objective scores were lower for the revision group compared with the primary group. On analysis of the subjective scores, the main differences noticed between the two groups were in the pain level and the activity level. On analysis of the objective IKDC scores, main differences were noticed in passive motion deficit and finding of crepitus in various compartments. None of the revision ACL group patients in our study returned to original level of activity (pre–ACL injury). This can be explained by the presence of associated meniscal and chondral pathology and should form an important part of the counseling offered to revision ACL surgery patients prior to their operation. Patients who have a prosthetic ligament as the primary graft and are undergoing subsequent revision surgery merit separate discussion. In all cases, the first-stage 453

Anterior Cruciate Ligament Reconstruction revision surgery was more demanding and time consuming, as the synthetic graft evoked a lot of synovitis and scarring within the knee. Extra care was needed to identify the PCL before clearing the intercondylar notch. The extent of tunnel enlargement was also more pronounced in these cases.

REVIEW OF LITERATURE Noyes and Barber-Westin reported on 55 patients who had a revision ACL reconstruction with a BPTB autograft.33 The failure rate, which was determined in a fashion similar to that in their revision allograft report, was 24%. Of these 13 patients, six had a reharvested patellar tendon autograft. This was a heterogenous group, and the authors stratified the group of 55 knees into those who had an ACL reconstruction only, those who required a staged high tibial osteotomy, and those who required a concurrent ligament reconstructive procedure. The group requiring only ACL reconstruction had a failure rate of 16% (5/32 knees). Earlier, the same research group had also published their results of revision ACL surgery with the use of a BPTB allograft.39 They noted an incidence of 33% failure at a mean of 42 months. In this series, the allografts were obtained from tissue banks certified by the American Association of Tissue Banks (AATB) and were fresh-frozen at the time of procurement. The grafts had been sterilized with 25,000 gray of gamma irradiation. This amount of low-dose irradiation probably does not alter the mechanical properties of the graft. In fact, AATB has advocated use of low-dose irradiation for many years and several authors have used it for ACL allografts to improve the protection against bacterial contamination.42,43 Noyes et al advocate that allograft should not be considered as the first choice of graft for revision surgery. If no autograft is available for revision surgery, they advise augmentation of the allograft with the lateral extraarticular iliotibial band procedure to reduce the high failure rate associated with the use of allograft.33 Fox et al recently published their results of revision ACL reconstruction using nonirradiated patellar tendon allograft.69 Thirty-two of 38 patients (84%) were available for follow-up. The mean patient age was 28 years with a mean follow-up of 4.8 years (range 2.1–12.1). This is a good homogenous group of patients with critical evaluation of results. None of the patients in the series had meniscal allograft surgery, posterolateral reconstructions, high tibial osteotomies, or contralateral ACL deficiency or reconstruction. Of this patient group, 87% were subjectively satisfied, 87% had 0/1þ pivot shift, and 84% had a KT-1000 SSD of less than 3 mm. The authors quote a failure rate of 28% using stringent criteria, namely the presence of a positive 454

pivot-shift test (grade 1/2/3) and/or a KT-1000 result of more than 5 mm SSD. If the criteria used for definition are changed to SSD greater than 5 mm and pivot-shift grade 2 or more, then the failure rate is just 6%. The authors very correctly point out that the criteria used for defining failure after revision surgery are variable, which further complicates the comparison. The Pittsburgh series of Johnson et al20,21,48 used irradiated, fresh-frozen allografts. Nine of the 25 patients had a KT-1000 maximum manual difference of greater than 5.5 mm. Eighty percent had grade 0 or 1 Lachman result, and 20% had grade 2 Lachman result; 76% of patients were satisfied with the results.21 Uribe et al reported on 54 patients with revision ACL reconstruction using a variety of grafts including ipsilateral patellar tendon autograft, contralateral patellar tendon autograft, allograft patellar tendon, and hamstring autograft. All the patients had an improvement in their objective stability; however, only 54% of the patients returned to their pre–ACL injury activity level.70 Battaglia et al34 recently published their experience of revision ACL reconstruction using freeze-dried allograft bone dowels. The advantages of these grafts are their ready availability, the elimination of donor site (iliac crest) morbidity, and their ability to provide sufficient structural support for the new tunnels. Although all these proposed benefits are true, with passage of time the allograft may become resorbed, compromising the stability of the ACL reconstruction. Our results compare favorably to those published in the literature28,33,34,39,69–71 with regard to laxity measurements, and our failure rate is significantly lower. In only one case the graft had failed at 52 months and the patient complained of instability requiring revision, giving a failure rate of 2.04%. In another patient, the cruciometer reading was 5 mm, suggestive of increased laxity. However, this patient is coping well at present and has not had any further surgical intervention. These results have been achieved despite an uncompromised rehabilitation regimen, and we believe that this can be attributed at least partly to the two-stage technique we used, which allows for the consolidation of the bone graft in the tibial tunnel. These figures also represent the “worst-case” scenario, as no patient was lost to follow-up. This study has certain limitations. In an ideal world, we would have set up a randomized controlled trial comparing the results of a two-stage revision surgery with a onestage revision surgery to highlight the differences (if any). Although a two-stage surgery provides good bone for placement of the tibial tunnel, it exposes the patient to another surgical intervention. This may indeed have negative effects on the patient’s range of motion and pain after surgery and also may prolong the rehabilitation period. In the period of

Revision Anterior Cruciate Ligament Reconstruction the past 10 years, the senior surgeon has performed nine revision ACL reconstructions using a single-stage technique. As this is quite a small number, we did not compare the results with one-stage revisions. In our opinion, a singlestage technique should only be used if the placement of the primary tibial tunnel is so incorrect that it will not overlap at all with the correctly placed revision tunnel. This was rarely the case in our series with both tunnels. In this study, we decided to graft the tibial tunnel, as there was no other way of bypassing the defect in the bone created during the primary surgery. Bone grafting the primary tibial tunnel and ensuring its adequate healing prior to proceeding to the second stage of revision reconstruction ensured that the new tunnel could be drilled through an area with adequate bone stock, which in turn would not compromise the fixation achieved or the postoperative rehabilitation. In cases of femoral tunnels in this series, it was always possible to alter the technique of drilling the femoral tunnel (outside-in versus inside-out), thereby ensuring that the bony defect created during the primary procedure was avoided. Revision ACL surgery is both a challenging and a rewarding enterprise for the surgeon. It is challenging in that it uses all the surgeon’s experience and communication skills in dealing with these complex cases and patients. It also tests the surgeon’s surgical expertise and knowledge of fixation techniques and biological healing and thus the best predictable outcome for each patient. The treatment process benefits from a mature organizational setup and a competent team. The rewards are self-evident.

References 1. Thomas NP, Kankate R, Wandless F, et al. Revision anterior cruciate ligament reconstruction using a 2-stage technique with bone grafting of the tibial tunnel. Am J Sports Med 2005;33:1701–1709. 2. Brown CHJ, Carson EW. Revision anterior cruciate ligament surgery. Clin Sports Med 1999;18:109–171. 3. Aglietti P, Buzzi R, Simeone AJV, et al. Arthroscopic-assisted anterior cruciate ligament reconstruction with the central third patellar tendon. A 5–8 year follow-up. Knee Surg Sports Traumatol Arthrosc 1997;5:138–144. 4. Steiner ME, Hecker AT, Brown CHJ, et al. Anterior cruciate ligament graft fixation. Comparison of hamstring and patellar tendon grafts. Am J Sports Med 1994;22:240–246;discussion 6–7. 5. Thomas NP. The patient with the failed ACL reconstruction. In Clinical challenges in orthopaedics: the knee. City, 2000, Martin Dunitz, pp 51–57. 6. L’Insalata JC, Klatt B, Fu FH, Harner CD. Tunnel expansion following ACL reconstruction: a comparison of hamstring and patellar tendon autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234–238. 7. Wilson TC, Kantaras A, Atay A, et al. Tunnel enlargement after anterior cruciate ligament surgery. Am J Sports Med 2004;32:543–549. 8. Allen CR, Giffin JR, Harner CD. Revision anterior cruciate ligament reconstruction. Orthop Clin North Am 2003;34:79–98. 9. Azer FM. Revision anterior cruciate ligament reconstruction. Instr Course Lect 2002;51:335–342. 10. Berg EE. Tibial bone plug non-union: a cause of anterior cruciate ligament reconstructive failure. Arthroscopy 1992;8:380–384.

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11. Corsetti JR, Jackson DW. Failure of anterior cruciate ligament reconstruction: the biologic basis. Clin Orthop 1996;325:42–49. 12. Dunn WR, Lincoln AE, Hinton RY, et al. Occupational disability after hospitalization for the treatment of the anterior cruciate ligament. J Bone Joint Surg 2003;85A:1656–1666. 13. Dye SF. The future of anterior cruciate ligament restoration. Clin Orthop 1996;325:130–139. 14. Frank C. Future directions of ACL research. In The anterior cruciate ligament: current and future concepts. New York, 1993,Raven Press, pp 4449–4450. 15. Friedlaender GE. Immune responses to osteochondral allografts. Current knowledge and future directions. Clin Orthop 1983;174:58–68. 16. Friedlander GE. Current concepts review. Bone grafts. J Bone Joint Surg 1987;69A:786–790. 17. Getelman MH, Friedman MJ. Revision anterior cruciate ligament reconstruction surgery. J Am Acad Orthop Surg 1999;7:189–198. 18. Greis PE, Johnson DL, Fu FH. Revision anterior cruciate ligament surgery: causes of graft failure and technical considerations of revision surgery. Clin Sports Med 1993;12:839–852. 19. Harner CD. Editorial comment. Failed ACL surgery—a symposium. Clin Orthop 1996;325:2–3. 20. Johnson DL. Revision ACL surgery. In Ryder B. Knee surgery. Philadelphia, 1994, Williams & Wilkins, pp 877–895. 21. Johnson DL, Coen MJ. Revision ACL surgery. Etiology, indications, techniques and results. Am J Knee Surg 1995;8:155–167. 22. O’Brien WR, Friederich NF. Isometric placement of cruciate ligament substitutes. In The cruciate ligaments. Edinburgh, 1994, Churchill Livingstone, pp 595–604. 23. O’Neill DB. Arthroscopically assisted reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83:1329–1332. 24. Stapleton TR. Complications in anterior crucitae ligament reconstructions with patellar tendon grafts. Sports Med Arthrosc Rev 1997;5:156–162. 25. Vergis A, Gillquist J. Graft failure in intra-articular anterior cruciate ligament reconstructions: a review of the literature. Arthroscopy 1995;11:312–321. 26. Wetzler MJ, Bartolozzi AR, Gillespie MJ, et al. Revision anterior cruciate ligament reconstruction. Oper Tech Orthop 1996;6:181–189. 27. Wolf RS, Lemak LJ. Revision anterior cruciate ligament surgery. J South Orthop Assoc 2002;11:25–32. 28. Carson EW, Anisko EM, Restrepo C, et al. Revision anterior cruciate ligament reconstruction: etiology of failures and clinical results. J Knee Surg 2004;17:127–132. 29. Safran MR, Harner CD. Technical considerations of revision anterior cruciate ligament surgery. Clin Orthop 1996;325:50–64. 30. Grossman MG, El Attrache NS, Shields CL, et al. Revision anterior cruciate ligament reconstruction: three- to nine-year follow-up. Arthroscopy 2005;21:418–423. 31. Noyes FR, Barber-Westin SD. Revision anterior cruciate ligament surgery: experience from Cincinnati. Clin Orthop Rel Res 1996;325:116–129. 32. Noyes FR, Barber-Westin S. Revision anterior cruciate ligament surgery: report of 11-year experience and results in 114 consecutive patients. Instr Course Lect 2001;50:451–461. 33. Noyes FR, Barber-Westin SD. Revision anterior cruciate surgery with use of bone-patellar tendon-bone autogenous grafts. J Bone Joint Surg 2001;83A:1131–1143. 34. Battaglia TC, Miller MD. Management of bony deficiency in revision anterior cruciate ligament reconstruction using allograft bone dowels: surgical technique. Arthroscopy 2005;21:767. 35. Jaureguito JW, Paulos LE. Why grafts fail. Clin Orthop 1996;325:25–41. 36. Hefti F, Muller W, Jakob RP, et al. Evaluation of knee ligament injuries with the IKDC form. Knee Surg Sports Traumatol Arthrosc 1993;1:226–234. 37. Crawford E, Dewer M, Aichworth PM. The Westminster cruciometer for measurement of anterior cruciate instability: proceedings of BASK meeting December 1985. J Bone Joint Surg 1987;69B:159. 38. Getelman MH, Schepsis AA, Zimmer J. Revision ACL reconstruction: autograft versus allograft. Arthroscopy 1995;11:378.

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Anterior Cruciate Ligament Reconstruction 39. Noyes FR, Barber-Westin SD, Roberts CS. Use of allografts after failed treatment of rupture of the anterior cruciate ligament. J Bone Joint Surg 1994;76A:1019–1031. 40. Pelker RR, Friedlaender GE, Markham TE, et al. Effects of freezing and freeze-drying on the biomechanical properties of rat bone. J Orthop Res 1984;1:405–411. 41. Stevenson S. The immune response to osteochondral allografts in dogs. J Bone Joint Surg 1987;69:573–582. 42. Asselmeier MA, Caspari RB. A review of allograft processing and sterilization techniques and their role in transmission. Am J Sports Med 1993;21:170–175. 43. Noyes FR, Barber-Westin SD. Prospective evaluation of allograft meniscus transplantation: a minimum 2-year follow-up. Am J Sports Med 2006;34:2038–2039. 44. Ritchie JR, Parker RD. Graft selection in anterior cruciate ligament revision surgery. Clin Orthop 1996;325:65–77. 45. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 46. Shelbourne KD, O’Shea JJ. Revision anterior cruciate ligament reconstruction using the contralateral bone-patellar tendon-bone graft. Instr Course Lect 2002;51:343–346. 47. Colosimo AJ, Heidt RSJ, Traub JA, et al. Revision anterior cruciate ligament reconstruction with a reharvested ipsilateral patellar tendon. Am J Sports Med 2001;29:746–750. 48. Johnson DL, Swenson TM, Irrgang JJ, et al. Revision anterior cruciate ligament surgery: experience from Pittsburgh. Clin Orthop 1996;325:100–109. 49. Harvey AR, Thomas NP, Amis AA. Fixation of the graft in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2005;87A:593–603. 50. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar tendon graft and fixation type. Arthroscopy 2005;21:1202. 51. Freedman K, D’Amato M, Nedeff D, et al. Arthroscopic anterior cruciate ligament reconstruction. A metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 52. Grover DM, Howell SM, Hull ML. Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices. J Bone Joint Surg 2005;87A:381–390. 53. Kawakami H, Shino K, Hamada M. Graft healing in a bone tunnel: bone-attached graft with screw fixation versus bone-free graft with extra-articular suture fixation. Knee Surg Sports Traumatol Arthrosc 2004;12:384–390. 54. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35–43. 55. Weiler A, Hoffmann RFG, Siepe CJ, et al. The influence of screw geometry on hamstring tendon interference fit fixation. Am J Sports Med 2000;28:356–359. 56. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction. A meta-analysis. Arthroscopy 2001;17:248–257.

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57. Kousa P, Teppo L, Jarvinen NJ, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 58. Kousa P, Teppo L, Jarvinen NJ, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med 2003;31:174–181. 59. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med 1987;15:225–229. 60. Malek MM, DeLuca JV, Verch DL, et al. Arthroscopically assisted ACL reconstruction using central third patellar tendon autograft with press fit femoral fixation. Instr Course Lect 1996;45:287–295. 61. Brand J Jr, Weiler A, Caborn DNM, et al. Current concepts. Graft fixation in cruciate ligament reconstruction. Am J Sports Med 2000;28:761–774. 62. Vuori I, Heinonen A, Sievanen H, et al. Effects of unilateral strength training and detraining on bone mineral density and content in young women. A study of mechanical loading and deloading on human bones. Calcif Tissue Int 1994;55:59–67. 63. Brand JC Jr, Pienkowski D, Steenlage E, et al. Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque. Am J Sports Med 2000;28:705–710. 64. Giurea M, Zorilla P, Amis A, et al. Comparative pull-out and cyclicloading strength tests of anchorage of hamstring tendon grafts in anterior cruciate ligament reconstruction. Am J Sports Med 1999;27:621–625. 65. Weiler A, Hoffmann RF, Stahelin AC, et al. Hamstring tendon fixation using interference screws. A biomechanical study in calf tibial bone. Arthroscopy 1998;14:29–37. 66. Beynnon BD, Meriam CM, Ryder SH, et al. The effect of screw insertion torque on tendons fixed with spiked washers. Am J Sports Med 1998;26:536–539. 67. Harvey AR, Thomas NP, Amis AA. The effect of screw length and position on fixation of four strand hamstring grafts for anterior cruciate ligament reconstruction. Knee 2003;10:97–102. 68. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292–299. 69. Fox JA, Pierce M, Bojchuk J, et al. Revision anterior cruciate ligament reconstruction with nonirradiated fresh-frozen patellar tendon allograft. Arthroscopy 2004;20:787–794. 70. Uribe JW, Hechtman KS, Zvijac JE, et al. Revision anterior cruciate ligament surgery: experience from Miami. Clin Orthop Relat Res 1996;Apr:91–99. 71. Woods GW, Fincher AL, O’Connor DP, et al. Revision anterior cruciate ligament reconstruction using the lateral third of the ipsilateral patellar tendon after failure of a central-third graft: a preliminary report on 10 patients. Am J Knee Surg 2001;14:23–31.

PART M ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION FOR SKELETALLY IMMATURE PATIENTS OR PARTIAL TEARS

Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients Intrasubstance tears of the anterior cruciate ligament (ACL), a common injury in adults, are relatively rare in children and adolescents.1 Presumably, this difference in prevalence of ACL tears is due to anatomical and biomechanical differences that predispose skeletally immature knees to physeal and bone injury rather than ACL tears. Despite being an uncommon occurrence, ACL tears in children and adolescents have recently been reported with increasing frequency.2–20 The increased recognition of this injury may be attributed to an increase in sports participation combined with improved examination and diagnostic methods. When a skeletally immature patient presents with a torn ACL, the physician is confronted with a difficult decision because nonoperative treatment may result in instability with subsequent meniscal tears and early degenerative changes,2,6,9–11 and surgery may cause iatrogenic leg length discrepancy or angular deformities.5–7,12–15 Management of ACL tears in skeletally immature patients remains controversial because of a deficiency in the basic science literature on physeal growth and response to injury. Clinical studies published on the treatment of this condition have contributed to the confusion by having poor methodology with low levels of evidence and combining patients with different levels of maturation and methods of treatment.* Although a fundamental lack of knowledge is the cause of the controversy surrounding treatment of ACL injuries in children and *References 4, 7, 11, 12, 14–19

adolescents, a rational approach to management of this problem can still be developed based on current understanding of the natural history of this injury, normal growth and development, response of the physis to injury, and treatment options. This approach enables the surgeon to estimate whether the patient is at high, intermediate, or low risk of iatrogenic growth disturbance and to choose the method of treatment depending on the level of risk.

59 CHAPTER

Allen F. Anderson Christian N. Anderson

NATURAL HISTORY The natural history of ACL tears in children and adolescents has not been clearly documented, but it can be extrapolated from the results of studies published on nonoperative treatment. The unique challenge of treating intrasubstance ACL tears in skeletally immature patients combined with the absence of an efficacious surgical procedure resulted in a historical approach of nonoperative treatment, consisting of bracing, quadriceps and hamstring strengthening, counseling, and activity modification. A growing body of evidence from studies of nonoperative treatment proves that the natural history of ACL tears in children and adolescents is generally poor for behavioral or other reasons. ACL deficient patients in this age group are noncompliant with activity modification, and consequently they often experience recurrent instability, meniscal damage, and sports-related disability. Kannus and Jarvinen10 treated 25 patients with grade II partial ACL tears and 457

Anterior Cruciate Ligament Reconstruction seven patients with grade III complete ACL tears. Eight years after the initial injury, the results were excellent or good for the patients with Grade II ACL tears. The longterm results of grade III ACL injuries were poor because these patients developed chronic instability and posttraumatic arthritis. Kannus and Jarvinen reported that the results of nonoperative treatment for complete ACL tears in this age group were not acceptable. Angel and Hall3 evaluated 27 children and adolescents who had a torn ACL. At the time of follow-up, the majority had pain and limitations of activity. Eleven of 12 patients in their series of children younger than age 14 were disabled with knee function. Graf et al9 found that seven of eight children treated conservatively sustained new meniscal tears within 15 months. McCarroll et al11 found that 37 of 38 adolescent patients had episodes of instability, and 27 of 38 had symptomatic meniscal tears. Eleven of 18 patients in the series of Mizuta et al20 developed degenerative changes within 51 months, and the researchers stated the results were “poor and unacceptable.” Millet et al21 also found that the incidence of meniscal injuries increased significantly in chronic cases. Ideally, operative treatment of ACL injuries in skeletally immature patients could be postponed until physeal closure. The results of these studies, however, indicate that nonoperative treatment may actually result in a greater risk to the knee than surgery.

ASSESSING SKELETAL MATURITY The central issue in treatment of ACL tears in the pediatric age group is the patient’s skeletal age, which determines the relative risk and potential consequences of iatrogenic physeal injury. Some skeletally immature patients will have a great deal of growth remaining, whereas others will have minimal growth of the distal femur and proximal tibial physes. The consequences of growth disturbance may be severe in the former patients and insignificant in the latter patients. The lack of specific documentation of skeletal maturity in clinical studies (i.e., wide-open physis) published on the treatment of ACL tears in skeletally immature patients is a source of the controversy surrounding the treatment of the condition. A rational approach to management of this problem can be based on estimation of the relative risk (high, intermediate, or low) by determining the patient’s chronological age, skeletal age, and physiological age. For large populations, chronological age is an excellent predictor of skeletal maturity; however, patients may show a significant variance from the average. Consequently, it is important to determine the skeletal age with radiographs. The most common method of estimating skeletal age is by comparing an anteroposterior radiograph of the 458

patient’s left hand and wrist with the age-specific radiographs in the Greulich and Pyle atlas.22 Physiological age can be determined with Tanner staging of sexual maturation.23 Patients are preliminarily staged prior to surgery by questioning them about the onset of menarche or growth of axillary hair. After induction of anesthesia and prior to surgery, Tanner staging is determined by examining the patient’s secondary sexual development, including the growth of pubic and axillary hair, breasts, and genitalia. Prepubescent patients are categorized in Tanner stage I and II of development, pubescent patients are in stage III, and postpubescent patients are in Tanner stage V (Table 59-1).

NORMAL GROWTH AND DEVELOPMENT The physes of the distal femur and proximal tibia are the most rapidly growing in the body. Anderson et al24 estimated that the distal femoral physis contributes 40% and the proximal tibia physis contributes 27% of the overall lower extremity length. More recently, Pritchett25 reported that the distal femur grows at 1.3 cm per year until the last 2 years of maturity, when the growth rate drops to 0.65 cm per year. The rates of the proximal tibial growth are 0.9 cm per year and 0.5 cm per year in the last 2 years. The peak height velocity for males is 13 to 15 years of age (average 13.5 years), and it rarely occurs before Tanner stage IV. Twenty percent of males do not hit peak height velocity until Tanner stage V. For females, the peak height velocity occurs in Tanner stage III between 11 and 13 years of age (average 11.5 years). Peak height velocity in females precedes menarche by approximately 1 year. The severity of iatrogenic growth deformity is determined in part by the patient’s skeletal maturity at the time of injury. It has been estimated that complete closure of the proximal tibial physis in the average 12-year-old boy, complete closure of the distal femoral in a 13-year-old boy, or complete closure of the femoral and tibial physes of a 14-year-old boy will result in a 3-cm leg length discrepancy. A leg length discrepancy of 1.2 cm is considered within normal variance. The greatest concern, however, is not leg length discrepancy but angular deformity. An over-the-top femoral groove may result in a valgus/flexion deformity of the distal femur by damaging the perichondral ring of LaCroix. Damage to the anterior tibial physis may result in recurvatum. In the worstcase scenario, Wester et al26 estimated that a 14-year-old boy with 2 cm of remaining distal femoral growth could develop a 14-degree valgus deformity with a lateral femoral epiphysiodesis or 11-degree recurvatum with partial tibial physeal arrest. The results of these studies may be used to rank the potential consequences of an iatrogenic physeal injury.

Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients TABLE 59-1 Tanner Staging Classification of Secondary Sexual Characteristics Tanner Stage

Male Sexual

Female Sexual

Characteristics

Characteristics

Stage I

Testes <4 mL or <2.5 cm No breast development

(prepubescent)

No pubic hair

Stage II

No pubic hair

Testes 4 mL or 2.5–3.2 cm Breast buds Minimal pubic hair at base Minimal pubic hair on of penis

labia

Stage III

Testes 12 mL or 3.6 cm

Elevation of breast;

(pubescent)

Pubic hair over pubis

areolae enlarge

Voice changes

Pubic hair of mons

Muscle mass increases

pubis Axillary hair Acne

Stage IV

Testes 4.1–4.5 cm

Areolae enlarge

Pubic hair as adult

Pubic hair as adult

Axillary hair Acne Stage V

No growth

No growth

(postpubescent)

Testes as adult

Adult breast contour

Pubic hair as adult

Pubic hair as adult

Facial hair as adult Mature physique Other

Peak height velocity: 13.5

Peak height velocity:

years

11.5 years Menarche: 12.7 years

High-risk patients are prepubescent and in Tanner stages I and II of sexual maturation. Intermediate-risk patients are pubescent and in Tanner stage III. Low-risk patients with closing physes are in Tanner stage IV of sexual maturation.

BASIC SCIENCE RESEARCH ON PHYSEAL INJURY Although a deficiency exists in the age-specific basic science on physeal injuries, research has demonstrated the effects of drill hole damage to the physis and the results of placing a soft tissue graft through a transphyseal hole in animal models. Makela et al27 in 1988 drilled 2- and 3.2-mm transphyseal femoral holes in a rabbit model. The 2-mm holes destroyed 3% of the cross-sectional area of the physis, and the 3.2-mm holes destroyed 7% of the cross-sectional area. The destruction of 7% of the cross-sectional area of the growth plate caused permanent growth disturbance. Other researchers have evaluated the effect of placing a soft tissue graft across the physis. Guzzanti et al28

59

performed an ACL reconstruction with the semitendinosus tendon using 2-mm transphyseal femoral and tibial holes in immature rabbits. The femoral holes damaged 11% of the transverse diameter and 3% of the cross-sectional area of the physis, and the tibial holes damaged 12% of the transverse diameter and 4% of the cross-sectional area of the physis. Two of the 21 tibiae developed a valgus deformity, and one was shorter. The researchers recommended careful evaluation of the percentage of damage to the area of the physis before performing intraarticular methods of reconstruction of the ACL in adolescents. Houle et al29 performed a transphyseal ACL reconstruction in a rabbit model using four tunnel diameters ranging from 1.95 to 3.97 mm. They found that the larger drill holes caused more marked deformity and the soft tissue graft did not offer protection to physeal arrest. They recommended that tunnels involve 1% or less of the area of the physis when reconstructing the ACL in children. Janarv et al30 drilled 1.7-, 2.5-, and 3.4-mm holes in rabbit femurs. The hole in one femur was left empty, and the hole in the contralateral femur was filled with a soft tissue autograft. They found that growth retardation occurred when the drill injury destroyed 7% to 9% of the distal femoral physis, but no retardation was seen in injuries of 4% to 5% of the cross-sectional area of the physis. The soft tissue grafts prevented solid bone bridging, but a bone cylinder formed around the grafts. They also measured the tibial and femoral physis of a 12-year-old girl and estimated that an 8-mm drill hole would destroy 3% to 4% of the physis. In contrast to the results of Houle et al29 and Guzzanti et al,28 Stadelmaier et al31 found that a soft tissue graft placed in transphyseal drill holes of a canine model prevented formation of a bony bridge and subsequent growth disturbance. The effect of tensioning a graft across open physes has also been evaluated. Edwards et al32 found that tensioning a fascia lata autograft at 80N in a canine model caused valgus femoral and varus tibial deformities without radiographic or histological evidence of physeal bar formation, indicating the physes were responding to the Hueter-Volkmann principle, which states that application of compressive force perpendicular to the physes will inhibit longitudinal growth. This study illustrates the potential risks for ACL reconstruction in this age group, even with physeal-sparing procedures.

RISK FACTORS FOR IATROGENIC GROWTH DISTURBANCE The potential consequences of growth disturbance after ACL reconstruction in the skeletally immature knee have a major influence on decisions about surgical technique. Although the results of basic science studies on physeal 459

Anterior Cruciate Ligament Reconstruction injury in animals may not be entirely applicable to humans, several important risk factors for growth disturbance after physeal injury have been identified. The studies of Guzzanti et al28 and Houle et al29 demonstrated that the proximal tibial physis seems to be more vulnerable than the femoral physis to growth arrest. In general, the risk of growth disturbance is related to the extent of damage relative to the cross-sectional area of the physis. However, uncertainty still exists, even in animal models, regarding the size and orientation of the drill holes that can be made without causing growth disturbance. The drill hole size threshold for growth disturbance in animal models has been between 1% and 7% of the cross-sectional area of the physis.27,28–30 The holes should be drilled perpendicularly, rather than obliquely, to limit the area of damage to the physis. Although results have been mixed, placing a soft tissue graft across the physis appears to offer protection from bone bridging and growth arrest. Research also demonstrates that the physes are sensitive to compressive forces,32 and consequently ACL grafts, including those used in physeal sparing procedures, should not be overtensioned. Significant leg length discrepancy or angular deformity, although rare, has been reported after ACL reconstruction in skeletally immature patients.5,6,14 Kocher et al5 surveyed Herodicus and the ACL study group. One hundred and forty respondents reported 15 cases of growth disturbance. We have also seen two cases of valgus knee deformity after ACL reconstruction in adolescents. One of these patients had a staple placed across the lateral femoral physis.6 The other patient was a 12year-old boy who was recently seen 6 months after a transphyseal ACL reconstruction with an Achilles tendon allograft. The graft had failed, and the patient had a 3-degree valgus alignment of the normal knee and a 7-degree valgus alignment of the ACL deficient knee, without physeal arrest.

TREATMENT OPTIONS Case reports and animal studies showing iatrogenic growth disturbance after intraarticular transphyseal replacement have prevented clinicians from routinely applying proven methods of ACL reconstruction for adults to skeletally immature patients. Nonoperative management of ACL tears in children and adolescents is an especially seductive approach. The advantages of delaying surgery include additional psychological maturation of the patient, which facilitates compliance with postoperative rehabilitation, and greater skeletal maturity, which allows for less risky and more familiar traditional procedures. For these reasons, some surgeons still advocate a nonoperative approach despite the poor results.7,12,14 Other surgeons have performed primary repair33,34 or extraarticular replacement in this age group.9,11 Unfortunately, 460

these procedures have been found to be no more successful in children than they are in adults. Modified physeal-sparing intraarticular replacements have also been advocated to minimize the risk of physeal injury.19 Parker et al35 reconstructed the ACL by passing the hamstring tendons through a groove in the anterior aspect of the tibia and over the top of the lateral femoral condyle. Kocher et al13,18 reported the results of 44 Tanner stage I or II patients who were treated with a combined intraarticular and extraarticular reconstruction of the ACL. The iliotibial band was placed extraarticularly around the outside of the lateral femoral condyle and through the intercondylar notch and then sutured to the periosteum of the proximal tibia. Two patients in their series required reconstruction for graft failure. The mean IKDC subjective score for the remaining 42 patients was 96.7, and the mean growth from surgery to follow-up was 21 cm. The Lachman examination revealed that 23 patients were normal, 18 were nearly normal, and one was abnormal. The results of the pivot-shift test were normal in 31 patients. The researchers concluded that this procedure provided an excellent functional outcome with minimal risk of growth disturbance. Some surgeons have used transphyseal tibial holes and the over-the-top femoral position with autografts16,17 and allografts.12 Recently, Guzzanti et al36 recommended ACL reconstruction with singlestranded semitendinosus and gracilis tendon graft in Tanner stage I patients with a transepiphyseal tibial hole and a femoral over-the-top femoral position. Although these over-thetop procedures have not caused growth disturbances, they do not provide isometry of the graft. Odensten and Gillquist37 demonstrated that the femoral over-the-top position resulted in an average of 10 mm of graft elongation as the knee approached extension. If the over-the-top femoral position is used, the clinician should avoid rasping, which may damage the perichondral ring. ACL replacement procedures with intraarticular transphyseal placement of the graft remain controversial because of the potential for physeal injuries. Clinical studies documenting the safety of transphyseal replacement have primarily involved postmenarchal adolescent females or postpubescent adolescent males with physes that were near closure.11,12,38–40 Pressman et al15 performed an intraarticular replacement in 18 patients, only seven of whom had open physis and 11 of whom had closed or closing physis. Andrews et al12 and McCarroll et al7 also performed intraarticular replacements, but postoperatively their patients grew only 4.5 cm and 2.3 cm of height, respectively. The average age of the patients at the time of ACL reconstruction was greater than 14 years in other case series.38,40,41 The potential for leg length discrepancy or angular deformity is relatively low in these cohorts. Surgical treatment of patients who are in Tanner stage I or II of maturation presents greater

Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients

59

FIG. 59-1 Anteroposterior and lateral radiographs made 4 months after transepiphyseal anterior cruciate ligament (ACL) reconstruction in a 10-year, 8-month-old Tanner stage I male.

consequences if growth disturbance occurs, potentially resulting in significant limb length discrepancy or angular deformity. Only a few patients who were that immature were included in the previous clinical reports on transphyseal replacement. Consequently, the safety of transphyseal procedures for preadolescent children has not been substantiated in the clinical literature, and basic science studies have also failed to clearly demonstrate the safety of transphyseal drilling or placement of a soft tissue graft across the physis. Guzzanti et al42 recommended transphyseal reconstruction in Tanner stage II and III patients with semitendinosus gracilis grafts. They emphasized that the holes should not be larger than 6 mm. Anderson43 reported the preliminary results of a transepiphyseal replacement that followed the generally accepted principles of ACL reconstruction in adults but theoretically minimized the risk of physeal injury by not transgressing either the tibial or femoral physes (Figs. 59-1 and 59-2). Twelve patients, including three who were in Tanner stage I, four in Tanner stage II, and five in Tanner stage III, were evaluated at a mean of 4.1 years after surgery. The mean growth from the time of surgery to follow-up was 16.5 cm. The difference in lengths of the lower limbs, as measured on long leg radiographs, was not clinically relevant. The mean score on the IKDC Subjective Knee Form was 96.5. Ligament laxity testing with a KT-1000 arthrometer

revealed a mean side-to-side difference of 1.5 mm. The rating, according to the criteria of the Objective 2001 IKDC Knee Form,44 was normal for seven patients and nearly normal for five patients. Subsequently, eight additional patients (three in Tanner stage I, two in Tanner stage II, and three in Tanner stage III) had transepiphyseal replacement of the ACL with this technique, and the mean interval from surgery for the original series is now more than 6 years. One patient in the original study population, who rated 100 on the IKDC Subjective Score at 2 years, reruptured his ACL graft 4 years after surgery while playing sports. Another patient, who had an ACL replacement more recently, fell from a motorcycle 8 weeks after his ACL reconstruction and sustained a grade III injury to his medial collateral ligament and the ACL graft. This patient’s lack of compliance illustrates why it is difficult to treat patients in this age group. The Endobutton Continuous Loop broke in another patient 1 year after surgery. The washer was removed, and the patient’s knee was rated as excellent with no residual pathological laxity.

TREATMENT AND RECOMMENDATIONS Our approach to treatment of ACL tears in the pediatric age group is based on the patient’s skeletal age and sexual maturation, which determine the relative risk and potential 461

Anterior Cruciate Ligament Reconstruction

FIG. 59-2 This arthroscopic view shows the position of the quadruple hamstring graft after transepiphyseal anterior cruciate ligament (ACL) reconstruction.

consequences of iatrogenic physeal injury. Prepubescent patients in Tanner stages I or II of development, including males less than 12 years of age and females less than 11 years of age, are at high risk.

Transepiphyseal ACL reconstruction is recommended for high-risk patients because this procedure adheres to the generally accepted principles of ACL replacement in adults but theoretically minimizes the risk of physeal injury by not transgressing either the tibial or the femoral physis. For surgeons who are worried about the technical difficulty of a transepiphyseal ACL replacement, the physeal-sparing reconstruction described by Kocher et al13 may be an alternative. Although the iliotibial band is a relatively weak graft and is not placed isometrically on either the tibia or femur, the functional results appear to be good. Pubescent Tanner stage III patients, including males 13 to 16 years of age and females 12 to 14 years of age, are at intermediate risk. Transepiphyseal replacement is also recommended for this group because the threshold of safety of transphyseal drilling is currently unknown. More mature, low-risk, pubescent Tanner stage IV patients are treated with a transphyseal replacement using quadruple hamstring grafts fixed with an Endobutton proximally and screw and post distally (Fig. 59-3). Postpubescent patients in Tanner stage V of development, including males older than 16 years and females older than 14 years, may be treated safely with a standard adult ACL replacement.

FIG. 59-3 Anteroposterior and lateral radiographs demonstrating the position of the drill holes 6 months after transphyseal anterior cruciate ligament (ACL) reconstruction in a 14-year, 2-month-old Tanner stage IV male.

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TRANSEPIPHYSEAL ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Surgical Technique The injured lower limb is placed in an arthroscopic leg holder with the hip flexed to 20 degrees to facilitate C-arm fluoroscopic visualization of the knee in the lateral plane. The C-arm is positioned on the side of the table opposite the injured knee, and the monitor is placed at the head of the table. The tibial and femoral growth plates are visualized in both the anteroposterior and lateral planes before the limb is prepared and draped. When the distal part of the femur is viewed, the C-arm is adjusted so that the medial and lateral femoral condyles line up perfectly in the lateral plane. The C-arm is then rotated to visualize the extension of the tibial physis into the tibial tubercle on the lateral view of the tibia. An oblique 4-cm incision is made over the semitendinosus and gracilis tendons, which are dissected free, transected at the musculotendinous junction with use of a standard tendon stripper, and detached distally. The tendons are then doubled, and a #2 Fiberwire suture (Arthrex, Naples, FL) is placed in the ends of the tendons with a whipstitch. The doubled tendons are then placed under 4.5 kg (10 pounds) of tension on the back table with use of the Graftmaster device (Acufex-Smith & Nephew, Andover, MA). The arthroscope is inserted into the anterolateral portal, and a probe is inserted through the anteromedial portal. Intraarticular examination is systematically performed in the usual manner. Debris in the intercondylar notch is removed, and a minimal notchplasty is performed to visualize the anatomical footprint of the ACL on the femur. If a substantial meniscal tear is found, it is repaired. With the C-arm in the lateral position, the limb is adjusted to show a perfect lateral view (Fig. 59-4, B). The point of the guidewire is placed on the skin over the lateral femoral condyle, corresponding with the location of the footprint of the ACL on the femur. This point is approximately one-fourth of the distance from posterior to anterior along the Blumensaat line and one fourth of the distance down from the Blumensaat line (see Fig. 59-4, B). A 2cm lateral incision is made at this point, the iliotibial tract is incised longitudinally, and the periosteum is stripped from a small area of the lateral femoral condyle. The Carm is used to visualize the entry point of the guidewire in both the anteroposterior and the lateral planes. With the C-arm in the lateral planes and using a freehand technique, the point of the guidewire is introduced 2 to 3 mm into the femoral epiphysis. The pin is not angulated anteriorly or posteriorly but is kept perpendicular to the femur in the

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coronal plane. The C-arm is then rotated to the anteroposterior plane to make sure that the guidewire is not angulated superiorly or inferiorly. The guidewire is then driven across the femoral epiphysis, perpendicular to the femur and distal to the physis (see Fig. 59-4, A and B). Entrance of the guidewire into the intercondylar notch is subsequently visualized arthroscopically. The guidewire should enter at the center of the anatomical footprint of the ACL on the femur. This femoral guidewire is left in place, and a second guidewire is then inserted into the anteromedial aspect of the tibia through the epiphysis with the aid of a tibial drill guide. From the direct lateral position, the C-arm is rotated externally approximately 30 degrees to clearly demonstrate the physis extending into the tibial tubercle. The guidewire is then drilled into the tibial epiphysis under real-time fluoroscopic imaging (see Fig. 59-4, C). The handle of the drill guide must be lifted for the pin to clear the anterior part of the tibial physis. The pin should enter the joint at the level of the free edge of the lateral meniscus and in the posterior footprint of the ACL on the tibia. The appropriate position of both guidewires should be confirmed arthroscopically at this point. Tendon sizers are used to measure the diameter of the quadruple tendon graft (which typically ranges from 6 to 8 mm). A tight fit is important; consequently, the smallest appropriate drill is used to ream over both guidewires. The edge of the femoral hole is chamfered intraarticularly, and the width of the lateral femoral condyle is measured. The appropriate EndobuttonCL (2–3 cm) is chosen so that approximately 2 cm of the quadruple hamstring tendon graft will remain within the lateral femoral condyle. The Endobutton-CL is then passed around the middle of the double tendons and is looped inside of itself to secure the tendons proximally (Fig. 59-5). Alternatively, the tendons can be placed through the continuous loop before the tendon ends are sutured together. However, this requires drilling and measuring the length of the femoral hole before graft preparation. Otherwise, it is difficult to determine the appropriate length of the Endobutton-CL necessary to leave 2 cm of the tendon graft within the lateral femoral condyle. A #5 Fiberwire suture is placed in one end of the Endobutton, and a suture passer is used to pass it from anterior to posterior through the tibia and out the lateral femoral condyle (see Fig. 59-5). The Endobutton and tendons are then pulled up through the tibia and out of the femoral hole with use of the #5 suture. An Endobutton washer (Smith & Nephew, Memphis, TN), 3 to 4 mm larger than the femoral hole, is placed over the Endobutton. Tension is then applied to the tendons distally, pulling the Endobutton and washer to the surface of the lateral femoral condyle (Fig. 59-6). The washer is necessary to anchor the graft proximally because the hole in the lateral femoral

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A

B

C FIG. 59-4 Anteroposterior (A) and lateral (B) views demonstrating the position of the guidewire in the femoral epiphysis. C, Lateral view of the tibia, demonstrating the position of the tibial guidewire. Although the guidewire appears to enter the tibial tubercle in this view, it actually enters the epiphysis medial to the tibial tubercle.

condyle is larger than the Endobutton. The graft is placed under tension, and the knee is then extended to determine arthroscopically whether there is impingement of the graft on the intercondylar notch. Although an anterior notchplasty is usually unnecessary when this technique is used, if the anterior outlet of the intercondylar notch touches or indents the graft in terminal extension, a small portion of the anterior outlet may be removed. With the knee in 10 degrees of flexion, the quadruple hamstring graft is secured distally by tying the #5 Fiberwire sutures over a tibial screw and post that is placed medial to the tibial tubercle apophysis and distal to the proximal tibial physis. If the tendon graft extends through the tibial drill hole, it is also secured to the periosteum of the anterior tibia with multiple #1 Ethibond sutures with use of figure-eight stitches (see Fig. 59-6). The subcutaneous tissue and skin are closed in a routine fashion, and a hinged brace is applied.

Postoperative Rehabilitation The patient’s knee is placed in a hinged brace postoperatively. Phase I of rehabilitation is started as soon as the 464

patient awakes after surgery. The patient is encouraged to perform quadriceps muscle contraction and straight-leg raises. Cryotherapy is used for 5 to 10 minutes every hour. Range-of-motion exercises and hamstring muscle stretches while the patient is prone are started the day after surgery. The patients who did not have a meniscal repair are allowed to walk with crutches with weight bearing as tolerated. The patients who underwent a meniscal repair are allowed only toe-touch weight bearing for 6 weeks. At 1 week after surgery, the goal is a range of motion from 0 degrees of extension to 90 degrees of flexion. Phase II of rehabilitation, the strengthening phase, lasts from 2 to 11 weeks postoperatively. Active range-of-motion exercises along with patella mobilization and electrical muscle stimulation are begun. Patients progress through the exercises at their own pace. They are fitted with a functional knee brace 2 weeks after surgery, and full weight bearing is encouraged. Exercises, which are introduced into the rehabilitation program in order of increasing difficulty, include hamstring and quadriceps muscle stretching and strengthening, proprioception exercises, functional strengthening, and aquatic strengthening exercises. The goal is a

Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients

FIG. 59-5 The semitendinosus and gracilis tendons are pulled up through the tibia and out of the lateral femoral condyle with use of the #5 suture in the Endobutton. (Courtesy Deliah Cohn.)

full range of motion equal to that of the contralateral normal knee at 6 weeks after surgery. Phase III of rehabilitation lasts from 12 to 20 weeks postoperatively. This phase included functional strengthening, straight-line jogging, plyometric exercises, sport cord exercises for jogging, lateral movement, and foot agility exercises. At 16 to 20 weeks postoperatively, patients are permitted to perform functional activities, including fullspeed running, while wearing the brace. They are allowed to advance to full activity, including competitive sports, 28 weeks after surgery.

PHYSEAL-SPARING ACL RECONSTRUCTION WITH THE ILIOTIBIAL BAND The following is the technique described by Kocher et al.13,18 Although it is not an isometric ACL replacement, the functional results may be good. If this technique is

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FIG. 59-6 The Endobutton washer is placed over the Endobutton, and the washer is pulled back to the surface of the lateral femoral condyle. The quadruple hamstring grafts are secured distally by tying the #5 Fiberwire sutures over a tibial screw and post. (Courtesy Deliah Cohn.)

chosen, the defect in the iliotibial band over the vastus lateralis muscle should be closed. Failure to do so may result in a cosmetic problem caused by herniation of the vastus lateralis muscle. This procedure, a modification of the McIntosh and Darby13 intraarticular and extraarticular ACL reconstruction, is performed with the patient supine and a tourniquet on the proximal thigh. A 6- to 10-cm incision is made from the lateral joint line along the superior border of the iliotibial band. The iliotibial band is exposed, and incisions are made along its superior and inferior margins from Gerdy’s tubercle for a distance of 15 and 20 cm proximal to the joint line, depending on the patient’s size. The iliotibial band is detached proximally, dissected free from the lateral capsule, and tubularized with a whipstitch using a #5 Ethibond suture. Arthroscopy is then performed through anteromedial and anterolateral portals. Remnants of the torn ACL and fat pad are resected, and a small notchplasty is performed. Soft tissue is removed from the over-the-top position of the lateral femoral condyle, but care is taken to avoid injury to the perichondral ring, which is close to the 465

Anterior Cruciate Ligament Reconstruction over-the-top position. Another incision is made parallel to the medial border of the patellar tendon, extending from the joint line for a distance of 4 cm distally. Dissection is carried down to the periosteum. The physis is identified with the use of a Keith needle. A curved clamp is placed under the intermeniscus ligament, and a groove is made in the proximal tibial epiphysis with the use of a small curved rasp. Care is taken to avoid damage to the anterior tibial physis. The iliotibial band graft is then pulled into the knee with a full-length clamp or tendon passer that is passed through the anteromedial portal, over the top of the lateral femoral condyle, and out the lateral capsule. The clamp is then passed under the intermeniscal ligament, and the graft is regrasped and pulled into the medial incision. The graft is seated into the groove in the tibial epiphyses, placed under tension, and sutured to the lateral femoral condyle at the insertion of the lateral intermuscular septum with the knee

in 90 degrees of flexion and 15 degrees of external rotation (Fig. 59-7). The periosteum is incised distal to the physis, and a trough is made in the metaphysis. The graft is placed under tension and sutured to the periosteum at this location with the knee in 20 degrees of flexion. The defect created by harvesting the iliotibial band is closed over the vastus lateralis muscle. The lateral patella reticulum is left open to avoid excessive pressure on the lateral facet of the patella. The wounds are closed in a routine fashion.

Postoperative Rehabilitation The patient’s knee is placed in a hinged knee brace for 6 weeks postoperatively. A continuous passive motion (CPM) machine set for range of motion of 0 to 90 degrees is used for the first 2 weeks after surgery. The patient is maintained on partial weight bearing for 6 weeks. Thereafter, the

FIG. 59-7 The iliotibial band graft is passed over the top of the lateral femoral condyle, through the knee, under the intermeniscal ligament, and into the groove in the proximal tibia. The graft is sutured to the lateral femoral condyle with the knee in 90 degrees of flexion and 15 degrees of external rotation. It is then sutured to the periosteum of the proximal tibia with the knee in 20 degrees of flexion. (Courtesy Deliah Cohn.)

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Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients protocol for rehabilitation is similar to that used for transepiphyseal ACL reconstruction.

TRANSPHYSEAL ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Surgical Technique The injured lower limb is placed in an arthroscopic leg holder and scrubbed, prepped, and draped in a standard fashion. With the knee in 60 degrees of flexion, an oblique 4-cm incision is made over the semitendinous and gracilis tendons, which are dissected free, transected at the musculotendinous junction with use of a standard tendon stripper, and detached distally. A #2 Fiberwire suture is placed in each end of each tendon with an interlocking whipstitch. Tendon sizers are used to measure the diameter of the quadruple hamstring grafts, which typically range from 6 to 8 mm. The doubled tendons are then placed under 4.5 kg (10 pounds) of tension on the back table with use of the Graftmaster device (Acufex-Smith Nephew, Andover, MA). The arthroscope is inserted into the anterolateral portal, and a probe is inserted through the anteromedial portal. Intraarticular examination is systematically performed in the usual manner. Debris in the intercondylar notch is removed, and a minimal notchplasty is performed to visualize the anatomical footprint of the ACL on the femur. Care is taken not to enlarge the posterior arch of the intercondylar notch because the femoral physis is in close proximity. If a substantial meniscal tear is found, it is repaired. The point of the tibial drill guide is inserted through the anteromedial portal. The guide is set at a 55-degree angle and oriented so that the guide pin enters the anteromedial aspect of the tibia at a 65- to 70-degree angle in the coronal plane. The pin should enter the joint at the level of the free edge of the lateral meniscus and in the posterior footprint of the ACL on the tibia. The tibial hole is reamed over the guidewire using a standard cannulated drill bit. A tight fit of the graft within the tibial tunnel is important; consequently, the smallest appropriate drill bit is used to ream the tibial hole. After drilling the tibial tunnel, the debris around the hole is removed with a shaver. The knee is flexed to at least 90 degrees prior to insertion of the femoral guidewire. An over-the-top femoral guide is used that leaves 2 mm of bone between the drill hole and the posterior cortex of the lateral femoral condyle. The 2.7-mm passing pin is advanced through the offset guide and through the lateral femoral condyle until it penetrates the lateral femoral cortex. The pin may be palpated under the skin distal to the tourniquet. An acorn reamer that matches the diameter of the graft is used to create the femoral tunnel. The femoral hole is drilled to a depth of 30 to 35 mm at the 10:30 position

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in the left knee and the 1:30 position in the right knee. The depth of the femoral hole should be 10 mm greater than the desired graft insertion into the lateral femoral condyle so as to allow for rotation of the Endobutton. The Endobutton 4.5-mm reamer is then drilled over the guidewire and out the lateral femoral cortex. The femoral hole is chamfered to minimize graft fraying. The Endobutton depth gauge is used to measure the length of the femoral tunnel from the anterolateral femoral cortex to the opening in the intercondylar notch. The Endobutton-CL that leaves 20 to 25 mm of graft within the femoral tunnel is chosen. A #5 Ethibond suture is passed through one of the outside holes of the Endobutton. This suture is used to pass the Endobutton through the tibia and femur. A #2 Ethibond suture is passed through the other outside hole of the Endobutton, and it is used to rotate the Endobutton after it exits the anterolateral femoral cortex (Fig. 59-8). The hamstring grafts are then passed through the Endobutton-CL, creating a quadruple graft. Both strands of the #5 and #2 sutures in the Endobutton are passed through the eyelet of the passing 2.7-mm pin. The passing pin is inserted up through the tibial and femoral holes, piercing the quadriceps and skin proximal to the knee (see

FIG. 59-8 The #2 and #5 Ethibond sutures are threaded through the eyelet of the 2.7-mm passing pin. The passing pin is inserted up through the tibial and femoral holes, piercing the quadriceps muscle and skin. The pin is then pulled out of the femur proximally to pass the sutures. (Courtesy Deliah Cohn.)

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Anterior Cruciate Ligament Reconstruction

FIG. 59-9 The #5 suture is pulled first, advancing the Endobutton and graft. The #2 suture is then pulled to rotate the Endobutton external to the femur. (Courtesy Deliah Cohn.)

Fig. 59-8). The pin is then pulled out of the femur proximally to pass the sutures. The #5 suture is pulled first, advancing the Endobutton and graft into the femoral hole (Fig. 59-9). The #2 suture is pulled next, rotating the Endobutton external to the femur. The graft is then pulled distally, locking the Endobutton on the outside of the femoral cortex. Secure fixation should be felt. Then the #2 and #5 sutures in the Endobutton are removed. The knee is cycled through a range of motion several times to pretension the graft. The graft is placed under tension, and the knee is then extended to determine arthroscopically whether there is impingement of the graft on the intercondylar notch. If the anterior outlet of the intercondylar notch touches or indents the graft in terminal extension, a small portion of the anterior outlet may be removed. With the knee in 20 degrees of flexion, the quadruple hamstring graft is secured distally by tying the #5 Fiberwire sutures over a tibial Bioscrew and post that is placed medial to the tibial tubercle apophysis and distal to the proximal tibial physis (Fig. 59-10). If the tendon graft extends through the tibial drill hole, it is also secured to the periosteum of the anterior tibia with multiple #1 Ethibond sutures with use of figureeight stitches. The subcutaneous tissue and skin are closed in a routine fashion, and a hinged brace is applied.

Postoperative Rehabilitation The postoperative rehabilitation is the same as that described for the transepiphyseal ACL reconstruction technique.

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FIG. 59-10 The graft is pulled distally, locking the Endobutton on the outside of the femoral cortex. The quadruple hamstring graft is secured distally by tying the #5 Fiberwire sutures over a tibial Bioscrew and post. (Courtesy Deliah Cohn.)

References 1. Rang M In Children’s fractures, ed 2Philadelphia, 1983, Lippincott, pp 290–296. 2. Aichroth PM, Patel DV, Zorilla P. The natural history and treatment of rupture of the anterior cruciate ligament in children and adolescents. A prospective review. J Bone Joint Surg 2002;84B:618–619. 3. Angel KR, Hall DJ. Anterior cruciate ligament injury in children and adolescents. Arthroscopy 1989;5:197–200. 4. Brief LP. Anterior cruciate ligament reconstruction without drill holes. Arthroscopy 1991;7:350–357. 5. Kocher MS, Saxon HS, Hovis WD, et al. Management and complications of anterior cruciate ligament injuries in skeletally immature patients: survey of the Herodicus Society and the ACL Study Group. J Pediatr Orthop 2002;22:452–457. 6. Lipscomb AB, Anderson AF. Tears of the anterior cruciate ligament in adolescents. J Bone Joint Surg 1986;68A:19–28. 7. McCarroll JR, Shelbourne KD, Porter DA, et al. Patellar tendon graft reconstruction for midsubstance anterior cruciate ligament rupture in junior high school athletes. An algorithm for management. Am J Sports Med 1994;22:478–484. 8. Stanitski CL, Harvell JC, Fu F. Observations on acute knee hemarthrosis in children and adolescents. J Pediatr Orthop 1993;13:506–510. 9. Graf BK, Lange RH, Rujisaki CK, et al. Anterior cruciate ligament tears in skeletally immature patients; meniscal pathology at presentation and after attempted conservative treatment. Arthoscopy 1992;8:229–233. 10. Kannus P, Jarvinen M. Knee ligament injuries in adolescents. Eight year follow-up of conservative management. J Bone Joint Surg 1988;70B:772–776. 11. McCarroll JR, Rettig AC, Shelbourne KD. Anterior cruciate ligament injuries in the young athlete with open physes. Am J Sports Med 1988;16:44–47. 12. Andrews M, Noyes FR, Barber-Westin SD. Anterior cruciate ligament allograft reconstruction in the skeletally immature athlete. Am J Sports Med 1994;22:48–54.

Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients 13. Kocher MS, Sumeet G, Micheli L. Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents. J Bone Joint Surg 2006;88:283–293. 14. Koman JD, Sanders JO. Valgus deformity after reconstruction of the anterior cruciate ligament in a skeletally immature patient. A case report. J Bone Joint Surg 1999;81:711–715. 15. Pressman AE, Letts RM, Jarvis JG. Anterior cruciate ligament tears in children: an analysis of operative versus nonoperative treatment. J Pediatr Orthop 1997;17:505–511. 16. Bisson LJ, Wickiewicz T, Levinson M, et al. ACL reconstruction in children with open physes. Orthopedics 1998;21:659–663. 17. Lo IK, Kirkley A, Fowler PH, et al. The outcome of operatively treated anterior cruciate ligament disruptions in the skeletally immature child. Arthroscopy 1997;13:627–634. 18. Micheli LJ, Rask B, Gerberg L. Anterior cruciate ligament reconstruction in patients who are prepubescent. Clin Orthop 1999;364:40–47. 19. Nakhostine M, Bollen SR, Cross MJ. Reconstruction of mid-substance anterior cruciate rupture in adolescents with open physes. J Pediatr Orthop 1995;15:286–287. 20. Mizuta H, Kubota K, Shiraishi M, et al. The conservative treatment of complete tears of the anterior cruciate ligament in skeletally immature patients. J Bone Joint Surg 1995;77B:890–894. 21. Millett PJ, Willis AA, Warren RF. Associated injuries in pediatric and adolescent anterior cruciate ligament tears: does a delay in treatment increase the risks of meniscal tear? Arthroscopy 2002;18:955–999. 22. Greulich WW, Pyle S. Radiographic atlas of skeletal development of the hand and wrist, ed 2. Stanford, CA, 1959, Stanford University Press. 23. Tanner JM, Whitehouse RH. Clinical longitudinal standards for height, weight, height velocity, weight velocity and stages of puberty. Arch Dis Child 1976;51:170–179. 24. Anderson M, Green WT, Messnet MB. Growth and predictions of growth in the lower extremities. Am J Orthop 1963;45:1–14. 25. Pritchett JW. Longitudinal growth and growth-plate activity in the lower extremity. Clin Orthop 1992;275:274–279. 26. Wester W, Canale ST, Dutkowsky JP, et al. Prediction of angular deformity and leg length discrepancy after anterior cruciate ligament reconstruction in skeletally immature patients. J Pediatr Orthop 1994;14:516–521. 27. Makela EA, Vainionpaa S, Vihtonen K, et al. The effect of trauma to the lower femoral epiphyseal plate. An experimental study in rabbits. J Bone Joint Surg 1988;70B:187–191. 28. Guzzanti V, Falciglia F, Gigante A, et al. The effect of intraarticular ACL reconstruction on the growth plates of rabbits. J Bone Joint Surg 1994;75B:960–963. 29. Houle JB, Letts M, Yang J. Effects of a tensioned tendon graft in a bone tunnel across the rabbit physis. Clin Orthop 2001;Oct:275–281.

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30. Janarv PM, Wikstrom B, Hirsch G. The influence of transphyseal drilling and tendon grafting on bone growth: an experimental study in the rabbit. J Pediatr Orthop 1998;18:149–154. 31. Stadelmaier D, Arnoczky S, Dodds J, et al. The effects of drilling and soft tissue grafting across open growth plates. Am J Sports Med 1995;23:431–435. 32. Edwards TB, Greene CC, Baratta RV, et al. The effect of placing a tensioned graft across open growth plates. A gross and histologic analysis. J Bone Joint Surg 2001;83A:725–734. 33. Clanton TO, DeLee JC, Sanders B, et al. Knee ligament injuries in children. J Bone Joint Surg 1979;61A:1195–1201. 34. Engebretsen L, Svenningsen S, Benum P. Poor results of anterior cruciate ligament repair in adolescence. Acta Orthop Scand 1988;59:684–686. 35. Parker AW, Drez D Jr, Cooper JL. Anterior cruciate ligament injuries in patients with open physes. Am J Sports Med 1994;22:44–47. 36. Guzzanti V, Falciglia F, Stanitski CL. Physeal-sparing intraarticular anterior cruciate ligament reconstruction in pre-adolescents. Am J Sports Med 2003;31:949–953. 37. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for reconstruction. J Bone Joint Surg 1985;67A:257–262. 38. Aronowitz ER, Ganley TJ, Goode JR, et al. Anterior cruciate ligament reconstruction in adolescents with open physes. Am J Sports Med 2000;28:168–175. 39. Edwards PH, Grana WA. Anterior cruciate ligament reconstruction in the immature athlete: long-term results of intraarticular reconstruction. Am J Knee Surg 2001;14:232–237. 40. Matava MJ, Siegel MG. Arthroscopic reconstruction of the ACL with semi-tendinosus-gracilis autograft in skeletally immature adolescent patients. Am J Knee Surg 1997;10:60–69. 41. Shelbourne D, Gray T, Wiley B. Results of transphyseal anterior cruciate ligament reconstruction using patella tendon autograft in Tanner Stage III or IV adolescents with clearly open growth plates. Am J Sports Med 2004;32:1218–1222. 42. Guzzanti V, Falciglia F, Stanitski CL. Preoperative evaluation and anterior cruciate ligament reconstruction technique for skeletally immature patients in Tanner Stages II and III. Am J Sports Med 2003;31:941–948. 43. Anderson AF. Transepiphyseal replacement of the anterior cruciate ligament in skeletally immature patients. A preliminary report. J Bone Joint Surg 2003;85A:1255–1263. 44. Irrgang JJ, Anderson AF, Boland AL, et al. Development and validation of the international knee documentation committee subjective knee form. Am J Sports Med 2001;29:600–613.

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60 CHAPTER

Fotios Paul Tjoumakaris Anthony Buoncristiani James S. Starman Freddie H. Fu

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Anterior Cruciate Ligament Reconstruction of Partial Tears: Reconstructing One Bundle INTRODUCTION It has been estimated that approximately 60,000 to 75,000 anterior cruciate ligament (ACL) reconstructions are performed annually in the United States.1 This number is likely higher, as larger segments of the population have become active and participate in year-round sporting activities within the past several years. Outcomes of ACL reconstructions have been exhaustively studied, with many reports demonstrating successful return to sport and returning stability to the previously injured knee, particularly when compared with conservative management.2,3 Despite tremendous advances within the field of ACL reconstruction, success rates of primary reconstruction continue to hover between 70% to 95% within the best centers.4–6 With the increasing numbers of ACL being performed come the requisite number of cases that fail due to any variety of mechanisms: arthrofibrosis, extensor mechanism failure, recurrent patholaxity, and traumatic arthrosis.7 Several studies have demonstrated inferior results of revision surgery when compared with primary reconstruction, with many of these studies citing recurrent laxity as the primary mechanism of failure.8–12 The concept of recurrent laxity following a partial ACL injury or of a failed ACL reconstruction (with an intact, well-placed graft) can be treated within the same context. Both scenarios represent the same underlying anatomical defect: an isolated injury or absence of one of the bundles of the ACL that compromises the

ability of the knee to achieve stability and normal kinematics. Most ACL injuries are currently treated with reconstruction of the anteromedial (AM) bundle of the ACL. Recurrent laxity within this situation can be classified as recurrent tear of the graft, continued instability despite graft incorporation and healing with proper graft placement, and improper placement of the graft leading to continued laxity. Recurrent laxity after isolated partial ACL tears can be from isolated injury to the posterolateral (PL) or AM bundles that results in the inability of the knee to resist either rotatory or translational forces.13 Our technique of isolated PL or AM augmentation surgery has evolved from this foundation of applying anatomical principles of the ACL with the anatomical injury or failure pattern. This chapter outlines our technique for isolated PL bundle augmentation surgery within the setting of recurrent patholaxity after prior ACL reconstruction (and a healed, well-placed ACL graft) as well as after partial ACL disruption (isolated PL bundle injury). Please see Chapter 25 for a more detailed description of the ACL anatomy and doublebundle reconstruction technique.

PREOPERATIVE CONSIDERATIONS History ACL injuries typically occur in patients who participate in activities that require running,

Anterior Cruciate Ligament Reconstruction of Partial Tears: Reconstructing One Bundle jumping, or cutting. The classic scenario is often a young female athlete who sustains an injury while her foot is planted and slightly flexed, with a pivot moment applied to the knee. The ensuing injury is often characterized as a “pop” or other traumatic event, and swelling from a hemarthrosis is often present within minutes to hours after this insult. The patient history from a partial disruption of the ACL or from a patient who continues to have laxity despite having undergone prior reconstruction can be more vague. In some instances of partial ACL disruption, a traumatic event may occur, as is the case with a complete tear; however, in many cases patients may report a minor event in which the knee may have felt as though it shifted or rolled. Patients may have even gone back to competitive play the same day or within a week of the initial injury. In rare cases, there may be the minor complaint of pain with certain activity, with no specific injury reported. Within the setting of prior ACL reconstruction, patients are usually good historians with regard to their symptoms due to their prior experience. The patient in this setting may state that the knee continues to feel unstable or has no strength, or the patient may be observed by coaches and the training staff to lack this confidence on the knee due to subtle differences from the noninjured leg. Determining the exact amount of morbidity from these symptoms can be challenging but is very important in deciding whether surgical intervention is warranted.

Physical Examination The physical examination is very similar to that for most knee injuries. The knee is first inspected for any bruising or contusion that may indicate a more serious injury. The knee is checked for an effusion; if one is present and causing significant discomfort that impedes the physical examination, we will aspirate it from a superolateral portal. The range of motion is assessed; if limited, it may indicate concomitant meniscal pathology, although this is rarely seen with partial tears of the ACL. The knee is then examined for any tenderness along the joint line or joint line swelling, which also could represent the presence of meniscus pathology. The ligamentous evaluation is performed and compared with the contralateral extremity. The knee is checked first for valgus or varus instability at both 0 and 30 degrees. The Lachman and pivot-shift exams are then performed. The presence of a 2þ or 3þ Lachman with minimal shift may indicate involvement of the AM bundle with minimal involvement of the PL bundle. It is important to ascertain whether the patient is guarding or contracting the hamstrings, as these actions will impair the clinician’s ability to detect pathologic translations. The patient who has a large pivot shift with very minimal translation on the

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Lachman examination may have an isolated injury to the PL bundle. Rarely will patients have a positive anterior drawer sign, as the secondary stabilizers (medial meniscus/ posteromedial corner) are usually preserved within this injury pattern. The exam concludes with determination of the KT-1000 and its comparison with the contralateral extremity. A normal KT does not preclude the presence of injury to a portion of the ACL and is no substitute for a good physical examination.

Imaging We obtain plain radiographs in all patients to look for associated pathology. These radiographs include bilateral anteroposterior (AP) flexion weight-bearing views, a lateral view of the involved knee, and bilateral merchant or sunrise views. The radiographs are inspected for soft tissue swelling, an effusion, the presence of any fractures, physeal closure (for younger patients), and overall alignment. In patients who have undergone prior ACL reconstruction, the prior tunnel placement is evaluated as well as prior hardware placement and presence of tunnel expansion. Determination of joint space narrowing is paramount in determining prognosis, and any patient who demonstrates any evidence of arthrosis on the knee series is further evaluated with a long cassette to determine alignment. If significant side-to-side difference exists (greater than 3–5 degrees) on the alignment series, consideration is given to a realignment procedure to unload the affected compartment. We obtain a magnetic resonance imaging (MRI) scan in any patient suspected of having a partial ACL tear or continued laxity after prior single-bundle ACL reconstruction. The MRI is also useful to inspect for the presence of any meniscal or chondral pathology. Reviewing the MRI with an experienced radiologist is often necessary to accurately make the diagnosis and properly plan for surgical intervention. Studies have shown that MRI diagnosis of partial ACL tears can be challenging.14,15 In one series, nine of nine complete tears were accurately diagnosed by MRI, whereas only 1 of 9 partial tears were correctly identified.14 Findings that were suggestive of partial ACL tears in this series were the presence of some intact fibers, thinning of the ligament, a mass posterolateral to the ACL, and a wavy or curved ligament. The MRI is inspected for the presence of a bone contusion, as this usually indicates a more severe injury. One study demonstrated that only 12% of patients with a partial tear of the ACL had a bone contusion in comparison to 72% with complete tears.16 Additional coronal imaging may help to better delineate injury to the PL bundle, whereas the sagittal images are usually sufficient to visualize the AM fibers.

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Indications The indications for PL bundle augmentation surgery are not solely based on the preoperative evaluation. A patient who has undergone a prior single-bundle reconstruction with adequate graft placement and incorporation but who continues to experience patholaxity is perhaps the optimal candidate for this procedure. Patients who have suspected partial tears of the ACL with a positive pivot-shift examination, minimal translation with the Lachman maneuver, and an MRI that confirms the presence of the AM bundle are also qualified candidates for this procedure; however, these patients should demonstrate that they have recurrent laxity after a rehabilitation program and functional bracing regimen. These parameters are further defined arthroscopically once the entire injury pattern to the ACL is delineated and the presence of an intact AM bundle and disrupted PL bundle is found at surgery. Contraindications to surgical intervention include a patient who is unwilling to cooperate with the rehabilitation program and a patient who lacks a full or near-full range of motion on physical examination. The presence of open physes is not an absolute contraindication to using this technique; however, we do advise that younger patients be braced until they have reached skeletal maturity.

SURGICAL TECHNIQUE

drawn as well as the tibial tubercle. The borders of the patellar tendon and the anterior crest and posteromedial border of the tibia are identified. Three portholes are marked on the knee in the same fashion as in the double-bundle technique. The lateral porthole is located just off the lateral border of the patellar tendon with its most inferior border flush with the inferior border of the patella. The medial porthole is marked beginning at the inferior pole of the patella and extending distally just on the medial border of the patellar tendon. An accessory medial porthole that will later be used for the PL tunnel is marked approximately 2 cm medial to the AM porthole just at the level of the joint line. The tibial incision is marked on the AM aspect of the tibia midway between the anterior and posterior borders of the tibia. This incision is approximately 3 cm in length, beginning 2 cm distal to the medial joint line (Fig. 60-1). Diagnostic arthroscopy is undertaken after establishment of the lateral and medial portholes. Placement of the lateral porthole slightly superiorly obviates the need for excessive fat pad débridement as the arthroscope is introduced proximal to this vital structure through this viewing porthole. All three portholes are used for viewing during the procedure, and the surgeon is encouraged to obtain different vantage points from each porthole to ensure proper anatomical position of the femoral tunnel. We begin our arthroscopy in the patellofemoral joint, débriding only the

Anesthesia and Positioning Patients undergoing this procedure receive a femoral nerve block within the preoperative holding area. Once within the operating suite, the patient is given conscious sedation and placed supine on the operating room table. A thorough examination under anesthesia (EUA) is undertaken to confirm the findings from the office examination. A tourniquet is applied to the proximal thigh of the operative limb, and the contralateral extremity is placed in a padded well leg holder flexed and abducted at the knee and hip so that the operative field is cleared of any obstruction. Care is undertaken to pad the peroneal nerve and heel of the uninvolved leg. The operative limb is then placed in an arthroscopic leg holder that allows for greater than 100 degrees of knee flexion, and the foot of the table is lowered. The leg is then elevated for 5 minutes, and the tourniquet inflated to 100 mmHg greater than the systolic pressure. The leg is then prepped with povidone-iodine (Betadine) solution and draped free in the usual fashion.

Surgical Landmarks and Diagnostic Arthroscopy The knee is slightly flexed to 45 degrees, and the anatomical landmarks are identified. The inferior pole of the patella is 472

FIG. 60-1 Surface landmarks for surgery (left knee). Note the accessory medial porthole (AMP) placement and the superior placement of the lateral porthole (LP). MP, Medial porthole.

Anterior Cruciate Ligament Reconstruction of Partial Tears: Reconstructing One Bundle synovium that obstructs our view with a 4.5-mm full radius resector. The arthroscope is then swung down into the notch for a clear view of the ACL and posterior cruciate ligament (PCL). Varus stress is then applied to the knee in the figure-four position, and the lateral hemi-joint is inspected. Any articular or meniscal pathology is addressed at the time of inspection. The knee is then placed in slight flexion and valgus, and the medial hemi-joint is inspected. The scope is then brought back to the notch with the leg at 90 degrees of flexion (the neutral position). At this point, a spinal needle is used to localize the accessory medial porthole. The needle should be visualized above the anterior horn of the medial meniscus and should provide direct access to the origin of the PL bundle on the lateral femoral condyle (LFC). Placing the arthroscope in the medial porthole may help to delineate this more clearly. The accessory medial porthole is then incised with an upturned 11 blade, with care taken not to transect the anterior horn of the medial meniscus. The notch is inspected for disruption of the fibers of the ACL. A probe is used to apply stress to the damaged ligament. Placing the knee in the figure-four position can aid in viewing the root of the lateral meniscus as it enters the tibia. Just anterior to this structure and often confluent with the lateral meniscus is the insertion of the PL bundle of the ACL. These fibers are followed proximally to the LFC and assessed for competence. The knee is then brought back to the neutral position, and the AM bundle is assessed. A thermal device and small radius resector are used to carefully dissect out the fibers of the ACL, removing only tissue that has no origin or insertion. Once this has been achieved, the rupture pattern of the ACL is clearly seen and reconstruction of the damaged portion can be undertaken. In the setting of prior single-bundle ACL reconstruction, the graft is inspected for proper position and preparation is made for insertion of a PL bundle.

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The graft is marked at two sites on its proximal end, one line indicating the tunnel length and the other indicating where the Endobutton can be flipped for femoral fixation (Fig. 60-2). The graft is then washed with antibiotic solution and placed in a moistened sponge until it will be used during the procedure.

Technique for Reconstruction During the diagnostic examination, the femoral site of the PL bundle is marked with the thermal device where the fibers are avulsed. Knowledge of the origin of the ACL bundles on the LFC is paramount if no fibers of the ACL are remaining (Fig. 60-3). In the absence of this landmark (as in chronic cases or augmentation of a prior single-bundle reconstruction), general guidelines for the PL insertion are a point 8 mm posterior to the anterior articular margin of the lateral femoral condyle and 5 mm superior to the inferior articular margin of the LFC. A 3/32-mm Steinman pin is introduced from the medial accessory porthole directly to this point. For optimal visualization, the arthroscope can be inserted into the medial porthole during preparation of the femoral tunnel

FIG. 60-2 The allograft construct for posterolateral augmentation.

Graft Preparation Once the diagnosis has been confirmed, the graft is prepared by the surgical assistant on the back table. We prefer to use a looped tibialis anterior allograft for this procedure because the width and length of the graft are predictable. The graft is trimmed so that, when looped over, it will fit snugly into a 7-mm tunnel. A #2 braided suture is whipstitched up and down both ends of the graft for approximately 3 cm. Using a graft of at least 24 cm in total length will provide a looped graft of 12 cm, which is sufficient graft for the reconstruction. Once doubled over, the graft is secured via a loop to the Endobutton (Smith & Nephew, Andover, MA) device. Two sutures are then passed through the Endobutton device for later graft passage. An absorbable suture is used to suture the graft closed around the loop that secures the Endobutton.

FIG. 60-3 Anatomical relationship of the anteromedial (AM) bundle, posterolateral (PL) bundle, and lateral femoral condyle (LFC).

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FIG. 60-4 A, The placement of the posterolateral tunnel (PL) is just off the articular surface of the lateral femoral condyle (LFC). B, The tunnel is then drilled over the Steinman pin. AM, Anteromedial bundle.

(Fig. 60-4). The pin is tapped gently into the LFC to obtain initial purchase, and then the knee is flexed to approximately 115 to 120 degrees and the pin is sunk 5 to 10 mm into the condyle. The acorn reamer (7 mm) is then placed over the Steinman pin through the accessory medial porthole, and the femoral tunnel is drilled to a depth of 25 mm. The far cortex is then breached with the Endobutton drill, and the transcondylar length is measured with a depth gauge. If this length is greater than 35 mm, the tunnel is reamed an additional 5 mm for a total length of 30 mm. The tunnel length is then subtracted from the transcondylar length to determine the appropriately sized Endobutton, which is then fashioned to the graft by the surgical assistant. Attention is now turned to the tibial tunnel. It is paramount during this procedure that the tibial insertion of the PL bundle is accurately obtained so that the AM bundle is not compromised in any fashion. An incision is carried out based on our previous landmark, and the periosteum of the anteromedial tibia is exposed. The PL tibial insertion is identified at a site just medial to the attachment of the posterior horn of the lateral meniscus and slightly anterior to the PCL. The ACL director guide (Smith & Nephew, Andover, MA) is brought through the medial porthole and placed at this insertion site, set to 55 degrees. We prefer to use the direct “tip-to-tip” guide for accurate placement of the tunnel because the margin for error in this region is small. A 3/32-mm Steinman pin is drilled through this guide on the AM surface of the tibia (typically slightly medial to the halfway point of the anterior and posterior borders of the tibia). The pin is drilled so that the tip is visible within the joint. A curette is used to prevent overpenetration in this region (Fig. 60-5). The PL tibial tunnel is then reamed to a diameter of 7 mm, and debris is removed with a full-radius resector. The PL tunnel should avoid the AM footprint 474

entirely and be almost obscured from view by the fibers of the AM bundle. A Beath pin with a large looped suture on its distal end is then introduced through the accessory medial porthole and fashioned through the PL femoral tunnel out through the lateral aspect of the thigh. Care is taken to hyperflex the knee and retract the biceps manually to prevent injury to the common peroneal nerve with this maneuver. The looped suture is then brought into the joint and obtained via a suture grasper through the tibial PL tunnel. The sutures attached to the Endobutton are then fashioned through the loop, and the sutures are shuttled to the lateral aspect of the thigh (Fig. 60-6). The graft is then passed in

FIG. 60-5 A curette is used to prevent overpenetration upon drilling the posterolateral (PL) tibial tunnel. Note the presence of the anteromedial (AM) bundle anterior to the PL insertion. LFC, Lateral femoral condyle.

Anterior Cruciate Ligament Reconstruction of Partial Tears: Reconstructing One Bundle

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REHABILITATION The patient is placed in a hinged knee brace that is locked in extension for 1 week. Crutches are used for 4 to 6 weeks until quadriceps function returns. The brace is unlocked only for continuous passive motion (CPM) and range of motion during the first week. The patient is weight bearing as tolerated, barring any concomitant meniscal repair. The accelerated rehabilitation protocol as described by Irrgang is then followed.17 Return to sports is typically allowed after 6 months, provided adequate strength gains have been achieved. All patients are advised to use a functional knee brace when returning to sports during the first 1 to 2 years after reconstruction.

FIG. 60-6 Graft passage is assisted by shuttling the Endobutton sutures through the posterolateral (PL) tibial and femoral tunnels. AM, Anteromedial bundle; LFC, lateral femoral condyle.

COMPLICATIONS If particular attention to detail is paid with regard to the insertional anatomy of the ACL, complications are few with this procedure. In our series of patients, we have had no early failures, arthrofibrosis, or reported instability. One patient had to return to the operating room because of an improperly deployed Endobutton. Potential complications include symptomatic hardware, fracture of the lateral femoral condyle (which we have not seen with either the double or the augmentation technique), postoperative infection, and neurovascular injury.

RESULTS

FIG. 60-7 Final graft construct with crossing of the bundles with the knee in flexion. AM, Anteromedial bundle; LFC, lateral femoral condyle; PL, posterolateral bundle.

standard fashion and the Endobutton loop is flipped, providing femoral fixation (Fig. 60-7). The knee is then cycled from 0 to 120 degrees 20 times while holding tension on the tibial side to check for isometry and remove any slack within the allograft tissue. The PL bundle is then tensioned between 0 and 10 degrees with a biointerference screw measuring 7
30 mm. This fixation is augmented with a small staple on the AM aspect of the tibia with the remainder of the allograft. The knee is then checked for stability and range of motion.

ACL augmentation surgery is a novel approach to treat continued instability after prior ACL surgery as well as partial tears of the ACL. Published data in this area are lacking; however, our results have been encouraging. To date, the senior author (FF) has performed 20 PL bundle augmentation procedures for ACL insufficiency. Twelve of these patients had undergone prior ACL reconstruction, and the remaining eight patients had isolated partial tears of the PL bundle with symptomatic instability. Clinical results have shown a reduction in the pivot-shift exam from 2þ to 0, return to sports in all patients, and a total arc of motion of 133 degrees (from 139 preoperatively) at 20-month followup. No patient in our series has shown evidence of or reported the sensation of instability that was present preoperatively.

CONCLUSION Several studies have documented the natural history of partial tears of the ACL. Despite some early encouraging 475

Anterior Cruciate Ligament Reconstruction results, the majority of patients never return to their preinjury level of activity or sport.18,19 In a study by Barrack et al, more than 30% of patients had fair or poor results at the latest follow-up.20 Noyes et al followed 32 patients with partial ACL tears and found that 12 went on to complete rupture.21 Buckley et al found that 72% of partial ACL tears had activity related symptoms at early follow-up.22 With these disappointing results, combined with the residual instability that occasionally compromises patients who have had a prior ACL reconstruction, we believe that augmentation surgery may offer a more definitive solution. As techniques in ACL reconstruction become more refined, the surgical procedure will more clearly represent the original anatomical geometry of the ACL. Early recognition of the specific injury pattern of the ligament as well as attention to the clinical examination of prior single-bundle reconstructions are paramount in determining the appropriate procedure for each patient.

References 1. Johnson DL, Harner CD, Maday MG, et al. Revision anterior cruciate ligament surgery. In Fu FH, Harner CD, Vince KG (eds). Techniques in Knee Surgery, vol 1. Philadelphia, 1994, Williams & Wilkins, pp 877–895. 2. Grontvedt T, Engebretsen L, Benum P, et al. A prospective, randomized study of three operations for acute rupture of the anterior cruciate ligament. Five-year follow-up of one hundred and thirty-one patients. J Bone Joint Surg 1996;78A:159–168. 3. Sandberg R, Balkfors B, Nilsson B, et al. Operative versus nonoperative treatment of recent injuries to the ligaments of the knee. A prospective randomized study. J Bone Joint Surg 1987;69A:1120–1126. 4. Howell SM, Clark JA. Tibial tunnel placement in anterior cruciate ligament reconstructions and graft impingement. Clin Orthop Relat Res 1992;283:187–195. 5. Jaureguito JW, Paulos LE. Why grafts fail. Clin Orthop Relat Res 1996;325:25–41. 6. Ritchie JR, Parker RD. Graft selection in anterior cruciate ligament revision surgery. Clin Orthop Relat Res 1996;325:65–77.

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7. Newhouse KE, Paulos LE. Complications of knee ligament surgery. In Nicholas JA, Hershman EB (eds). The lower extremity and spine in sports medicine. St. Louis, 1995, Mosby, pp 901–908. 8. Getelman MH, Friedman MJ. Revision anterior cruciate ligament reconstruction surgery. J Am Acad Orthop Surg 1999;7:189–198. 9. Uribe JW, Hechtman KS, Zvijac JE, et al. Revision anterior cruciate ligament reconstruction surgery: experience from Miami. CORE 1996;325:91–99. 10. Johnson DL, Swenson TM, Irrgang JJ, et al. Revision anterior cruciate ligament reconstruction surgery: experience from Pittsburgh. CORE 1996;325:100–109. 11. Noyes FR, Barber-Westin SD. Revision anterior cruciate ligament reconstruction surgery: experience from Cincinnati. CORE 1996;325:116–129. 12. Noyes FR, Barber-Westin SD. Revision anterior cruciate ligament reconstruction surgery with use of bone-patellar tendon-bone autogenous grafts. J Bone Joint Surg 2001;83A:1131–1143. 13. Gabriel MT, Wong EK, Woo SL-Y, et al. Distribuition of in situ forces in the anterior cruciate ligament in response to rotatory loads. J Orthop Res 2004;22:85–89. 14. Lawrance JA, Ostlere SJ, Dodd CA. MRI diagnosis of partial tears of the anterior cruciate ligament. Injury 1996;27:153–155. 15. Umans H, Wimpfheimer O, Haramati N, et al. Diagnosis of partial tears of the anterior cruciate ligament of the knee: value of MR imaging. Am J Radiol 1995;165:893–897. 16. Zeiss J, Paley K, Murray K, et al. Comparison of bone contusion seen by MRI in partial and complete tears of the anterior cruciate ligament. J Comput Assist Tomogr 1995;19:773–776. 17. Irrgang JJ. Modern trends in anterior cruciate ligament rehabilitation: nonoperative and postoperative management. Clin Sports Med 1993;12:797–813. 18. Bak K, Scavenius M, Hansen S, et al. Isolated partial rupture of the anterior cruciate ligament. Long-term follow-up of 56 cases. Knee Surg Sports Traumatol Arthrosc 1997;5:66–71. 19. Sommerlath K, Odensten M, Lysholm J. The late course of acute partial anterior cruciate ligament tears. A nine to 15-year follow-up evaluation. Clin Orthop Relat Res 1992;281:152–158. 20. Barrack RL, Buckley SL, Bruckner JD. Partial versus complete acute anterior cruciate ligament tears. The results of nonoperative treatment. J Bone Joint Surg 1990;72B:622–624. 21. Noyes FR, Mooar LA, Moorman CT III, et al. Partial tears of the anterior cruciate ligament. Progression to complete ligament deficiency. J Bone Joint Surg 1989;71B:825–833. 22. Buckley SL, Barrack RL, Alexander AH. The natural history of conservatively treated partial anterior cruciate ligament tears. Am J Sports Med 1989;17:221–225.

PART N TREATMENT OF ASSOCIATED LIGAMENT INJURIES OR CARTILAGE DEFICIENCY

Anterior Cruciate Ligament Injury Combined with Medial Collateral Ligament, Posterior Cruciate Ligament, and/or Lateral-Side Injury INTRODUCTION A knee dislocation injury is a rare but potentially devastating injury. The definition of knee dislocation includes the grossly unstable knee, with a minimum of two of the four major knee ligaments injured, regardless of a reduced joint line.1 Some authors suggest that any combined anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries be considered a knee dislocation,2 although knee dislocations have been described without cruciate injury.3–5 The injury is commonly attributed to high-velocity motor vehicle accidents and low-velocity sports injuries, with the rate of knee dislocation reported to be 0.001% to 0.013% of all knee injuries.6–8 This may represent an underestimation of this devastating injury, as some knee dislocations spontaneously reduce before the patient receives a physical examination and the patient may suffer other physical injuries that require medical attention.1 Commonly, a knee dislocation involves injury to the ACL, PCL, and either the medial collateral ligament (MCL) or the lateral-side structures of the knee. Of knee dislocations, associated medial-side tears represent approximately 90% of all the injuries, whereas lateralside injuries represent approximately 10% of the knee dislocation injuries.9 We see almost 10 times more knee dislocations involving the medial side than we do involving the lateral side. Nonoperative treatment of knee dislocations involving the lateral

side usually results in a grossly unstable knee and causes severe functional disability for the patient. Because of these occurrences, acute reconstruction of all injured structures with all knee dislocations has been advocated; this recommendation has included knee dislocations involving the medial side.10,11 This approach has resulted in many stable but stiff knees after surgery. The morbidity associated with acute surgery for knee dislocations caused us to alter our treatment approach for knee dislocations to consider the healing potential of each torn structure. Although a knee dislocation involving the lateral side is an injury that requires surgery at least semi-acutely, a knee dislocation involving the medial side is not an injury that requires immediate surgery, and it may not require surgery at all. In this chapter we review our treatment approach to dislocated knees involving the ACL, PCL, and either the MCL injury or lateral-side structures. This approach was derived from an understanding of the injuries to the individual ligaments and their potential to heal, the natural history of the injury, and the effects of the injury in combination.

61 CHAPTER

K. Donald Shelbourne

LIGAMENT HEALING Anterior Cruciate Ligament The ACL does not generally heal after injury.12–15 Lyon et al13 found in a histological study that the

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Anterior Cruciate Ligament Reconstruction cellular composition of the ACL resembles that of fibrocartilage and that it has a poor capacity to heal. The injured ACL pulls completely apart as opposed to tearing interstitially, which diminishes the potential for healing. An incompetent ACL represents a complete tear. Yao et al16 found in a series of 21 partial ACL tears evaluated with magnetic resonance imaging (MRI) and confirmed with arthroscopic evaluation that the ACL tears showed ACL fibers in continuity and the ACL resisted probing. They also found that the MRI was less sensitive for partial tears compared with complete tears. MRI can occasionally demonstrate interstitial femoral-sided tears. These tears may heal spontaneously and can result in functional stability.

Posterior Cruciate Ligament In contrast to the ACL, PCL injuries have the potential for intrinsic healing (Fig. 61-1). Evaluation with MRI of acute PCL injuries has been found to be 99% to 100% sensitive and specific in documenting acute PCL tears. In contrast, MRI evaluation of chronic PCL laxity is less accurate than that of acute injury because the PCL appears to be healed

even when the patient has laxity.17–20 Shelbourne et al19 evaluated 40 patients who had acute PCL injuries with MRI at the time of the acute injury and again at a mean of 3.2 years after injury. Twenty-three patients had isolated PCL tears, and 17 patients had combined PCL and additional ligament injury. The healing of partial and complete tears was graded with MRI. The results showed 37 of 40 PCLs to be healed with continuity. All partial tears and most complete (19 of 22) PCL tears regained continuity. Twelve of 12 combined PCL/MCL injuries healed. In two patients with acute ACL, PCL, and MCL injuries, the MCL and PCL healed without treatment. Location, severity, and associated ligament injuries did not affect healing. The healed PCL demonstrated abnormal morphology in 25 of the 37 cases on follow-up.19 In a recent follow-up study at a mean of 4.6 years after knee dislocations to the lateral side, the PCL in 16 of 16 patients appeared healed on the MRI and no patient had more than 1þ laxity upon examination.21 Tewes et al20 evaluated follow-up MRIs on 13 patients with high-grade PCL injury at an average of 20 months postinjury. Their results showed 10 of 13 patients (77%) had regained MRI continuity of the PCL,

FIG. 61-1 A, Magnetic resonance image (MRI) of an acute posterior cruciate ligament (PCL) injury. B, A follow-up MRI image at 3 months after injury shows the PCL is in continuity, which may be read by the radiologist as a normal PCL.

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Anterior Cruciate Ligament Injury Combined with Medial Collateral Ligament, Posterior Cruciate Ligament, and/or Lateral-Side Injury although with an abnormal appearance. They could not correlate functional or clinical status with degree of clinical laxity.20 The time to obtain healing after acute PCL injury is yet unknown. However, Shelbourne et al22 described a firm endpoint and a painless posterior drawer at follow-up examination of acute PCL injuries about 2 weeks postinjury.

Medial Collateral Ligament The MCL is an extraarticular ligament with an intrinsic ability to heal. In contrast to the ACL, the MCL is made up of fibroblast-type cells with the potential to heal.13 Animal studies indicate the MCL can heal with scar tissue with strength and stiffness similar to that of native MCL.23,24 This intrinsic capacity to heal has also been observed clinically with isolated MCL injury.25,26 The ability of injured ligaments to heal may also be affected by extrinsic factors such as surgical apposition, immobilization, and early protected range of motion.27,28 Prolonged immobilization may adversely affect the mechanical properties by loss of collagen fiber orientation and decreased strength of the bone ligament junction.29,30 Long et al31 found in a rabbit model that the ultimate load of rabbit MCL treated with intermittent passive motion was four times greater than immobilized ligament, with improvements in matrix organization and collagen concentration. The location of MCL injury has also been found to affect healing potential. Proximal tears, which have a more pronounced blood supply, tend to heal rapidly and may lead to knee stiffness. Distal tears seem to heal more slowly, and patients usually do not develop range of motion problems.32,33

Lateral-Side Structures Lateral-side injuries involve several structures, and several combinations of injuries to these structures can occur with a knee dislocation. The lateral-side structures from anterior to posterior are the iliotibial band, lateral capsule, popliteus tendon, lateral collateral ligament, and biceps. These structures tend to tear distally and retract proximally and then heal “en masse” but do not heal in such a way to provide lateral stability. Lateral-side injuries are the only type of ligament knee injury that require acute repair.

CLINICAL EXAMINATION Listening carefully to the patient explain how the injury occurred and the position of the limb at the time of the injury combined with a thorough physical examination should allow the physician to arrive at a diagnosis. Evaluation of the uninjured extremity will establish a baseline and gain the

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patient’s confidence. Initial evaluation may be difficult because the patient will probably have pain, swelling, muscle spasm, and limited knee motion and will be apprehensive. The physician should have a high index of suspicion based on the history of the patient’s injury, especially with a multiligamentous knee injury, because 50% of knee dislocations will reduce before evaluation1,32 and capsular tears may prevent the appearance of significant effusion. The complications that arise from not recognizing associated injuries can be devastating. Close follow-up and reexamination are helpful. In addition, imaging studies and vascular surgery consultation may be needed. Clinical assessment of the ACL can be done using the Lachman test. A positive Lachman test, performed properly, is diagnostic of ACL disruption because the ACL prevents contribution from secondary stabilizers to anterior stability.34,35 The PCL is the primary restraint to posterior instability in the knee.26 To determine PCL deficiency, the involved knee should be compared with the noninvolved extremity to determine the proper relationship of the tibia to the femoral condyles. When the PCLs are intact, the anteromedial proximal tibia usually rests 1 cm anterior to the distal femoral condyles with 90 degrees of knee flexion. In patients with PCL deficiency, the anteromedial tibia will “sag” posteriorly in relationship to the femoral condyles.36,37 The most sensitive test for evaluating the PCL is the posterior drawer test at 90 degrees of flexion.38,39 Rubinstein et al39 found the posterior drawer test in conjunction with palpating anterior tibial step-off to be 96% accurate, 90% sensitive, and 99% specific, with an interobserver grade agreement of 81% in diagnosing PCL insufficiency. The posterior drawer test with internal tibial rotation can also provide assessment of medial structures. Posterior tibial translation with posterior drawer testing should decrease with internal rotation of the tibia as the medial capsular structures tighten. In combined PCL/medial-side injury, this reduction in the posterior laxity is lost. In the combined ACL/PCL deficient knee, the tibia will be subluxated posteriorly, making it more difficult to quantify the contribution of each ligament to anterior translation. It is important to compare and examine the noninvolved extremity and determine the proper relationship of the tibia to the femoral condyles. The pivot-shift test and flexion-rotation drawer test augment evaluation of ACL insufficiency but may not be useful in an injury involving the ACL, PCL, and MCL because these tests rely on the knee pivoting around intact medial structures. It is difficult to perform ligamentous testing on a patient with an acute knee dislocation. In particular, PCL laxity is difficult to determine because the patient may not be able to bend his or her knee to 90 degrees of flexion. 479

Anterior Cruciate Ligament Reconstruction Although MRI is helpful in determining the status of the PCL, treatment should not be determined based on MRI findings. It is important to remember that complete grade III PCL injuries can heal with continuity and little or no laxity when left in situ.19,20 Predictable healing of the torn PCL is more important than any laxity in the healed PCL. The fact that the PCL will heal with continuity is important to our treatment philosophy for knee dislocation injuries. An MCL injury is diagnosed and graded by physical examination. Palpation along the ligament will localize the site of the injury, which is critical to know in order to determine the treatment and rehabilitation process. The MCL is the primary medial restraint to valgus stress at 30 degrees of knee flexion. Valgus stress testing is preformed at 30 degrees of flexion to isolate the MCL and then again at 0 degrees of flexion to assess the contribution of capsular structures as well as the cruciate ligaments. In greater degrees of knee extension the ACL, PCL, posterior capsule, and posterior oblique ligaments assume a greater responsibility in preventing medial joint opening.40 Grading of MCL injury is based on tenderness, laxity, and the presence of a firm endpoint. A grade I injury has tenderness, no laxity with valgus stress testing at 30 degrees of knee flexion, and a firm endpoint. A grade II injury is similar but reveals some medial laxity and the presence of a firm endpoint. A grade III injury represents a complete disruption of the MCL with no palpable endpoint on valgus stress testing. A lateral-side knee injury usually appears differently than an isolated ACL injury. The knee has a mild effusion, but the lateral side of the leg appears swollen with ecchymosis from the lateral capsule avulsion that allows the hemarthrosis to dissipate into the lateral leg (Fig. 61-2, A, B). Lateral stability is evaluated with varus stress applied to the knee at

0 and 30 degrees of flexion. Grade 1 laxity involves tenderness over the lateral structures but no laxity and a good endpoint. Grade 2 lateral laxity involves tenderness and increased laxity with varus stress, but a good endpoint is felt. Grade 3 laxity involves tenderness and increased laxity with varus stress, and no endpoint is felt.

ASSOCIATED NEUROVASCULAR INJURY Vascular injury with high-velocity knee dislocation has been reported to be as high as 40% in some series.41 Shelbourne et al in a series of low-velocity sports injuries found a vascular injury rate of 4.8% (1 of 21).42 Peroneal nerve injuries have been reported in 14% to 35% of knee dislocations. Most, if not all, are associated with lateral-side injury. In a series of low-velocity sports injuries, four of 21 (19%) patients presented with peroneal nerve injury.43 All were associated with lateral-side injury. It should be emphasized that if the lateral side is injured, the peroneal nerve should be closely evaluated. Conversely, if the peroneal nerve is injured, careful evaluation of lateral-side structures is advised.

IMAGING Radiographic examination of the injured extremity is imperative to rule out associated fracture or joint subluxation. Initial views should include posteroanterior, lateral, and Merchant views.44 In the delayed setting, a flexed, 45-degree weight-bearing view will give more accurate assessment of tibiofemoral joint space.45 Additionally, a PCL avulsion fracture may be detected.

FIG. 61-2 Knee injury to the anterior cruciate ligament, posterior cruciate ligament, and lateral side. A, The knee has a mild effusion with increased lateral-side swelling. B, The lateral side shows ecchymosis from the lateral capsule, allowing the hemarthrosis to dissipate into the lateral side of the leg.

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Anterior Cruciate Ligament Injury Combined with Medial Collateral Ligament, Posterior Cruciate Ligament, and/or Lateral-Side Injury MRI may provide important information about the injured soft tissues and their site of disruption. MRI can also be used to radiographically evaluate the healing of the PCL. Although healing of the PCL on MRI correlates with clinical healing, there may be residual clinical laxity.19,20

TREATMENT PHILOSOPHY (PRINCIPLES) Our treatment principles have evolved over the last 22 years after observing and studying the outcome of injuries to individual structures and their potential to heal when left in situ, as well as the effects of the injuries in combination with other ligament injuries in the knee. Nonoperative treatment of knee dislocations has yielded mixed results, with some patients reporting residual, disabling laxity.10,46 Acute operative repair of multi-ligament injuries can provide knee stability but frequently results in permanent stiffness, primarily when injury to the medial side is involved. Previously, direct repair of all ligaments was advocated, but as ACL reconstruction techniques were developed, there was a shift toward repair of all injured structures in conjunction with ACL reconstruction. As PCL reconstruction techniques have improved, many authors now advocate combined ACL/PCL reconstructions in the acute setting.47,48 Knee dislocations are uncommon, and surgeons are more comfortable with a stable knee and the possibility of residual stiffness as opposed to the risk of potential instability. We believe that the observation of patients who had disabling problems after knee dislocation involving lateral-side injury led to a more aggressive approach toward acute surgical treatment of all combined injuries, without consideration for the injured structures causing the disability. Because surgical treatment has been favored, the healing potential of each injured structure has been ignored. We propose different treatment approaches depending on the degree and the combination of injured structures. The initial treatment approach is based on recognizing that the PCL and MCL can heal without surgery, whereas the ACL and lateral structures generally do not. Thus most ligament injuries do not require acute surgery, and in most cases immediate surgery is not desirable because of the increased incidence of arthrofibrosis and long-term loss of motion.49 An understanding of the healing response of individual structures provides an explanation for potential postoperative stiffness associated with acute surgery. The goal of treatment is to provide the patient with a functionally stable knee with full range of motion. In observing a young, athletically active population, we have found that patients who have a stable but stiff knee have disability and would prefer a knee with full range of motion that would allow a functional activity level. Once accurate

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diagnosis has been made and associated injuries evaluated, the treatment plan for the knee is formalized. The poor outcome from nonoperative treatment of knee dislocations has stemmed from inadequate treatment of the MCL or lateral-side structures. Our treatment approach revolves around making sure the MCL or lateral-side structures become stable and allowing the PCL to heal in situ such that it has 2þ laxity or less. The treatment of the MCL and lateral-side structures differs based on our knowledge of their potential or lack of potential to heal. An ACL reconstruction can be done as indicated based on the patient’s lifestyle and goals.

Combined Anterior Cruciate Ligament/ Posterior Cruciate Ligament/Medial Collateral Ligament Injury The initial treatment of patients who have a dislocated knee with a medial-side knee injury involves providing a means for the MCL to heal. In the past, we used either an immobilizer or a brace to limit valgus stress; however, we found that these devices were not restrictive enough to completely prevent the stress. Patients would also remove the device to shower or sleep. In 1990, we began using cast immobilization to totally limit valgus stress. The patient is initially placed in a cylinder cast with 20 degrees of flexion, and weight bearing is encouraged. The goal is to prevent valgus stress, allow healing of the MCL, and prevent stress deprivation of the joint surface.29 The cast is changed weekly in order to evaluate ligament healing. Gentle valgus stress testing is performed to check for an endpoint. Once stability is achieved in the MCL with a stable endpoint and the patient is pain free, the cast is discontinued. Typically, proximal MCL injuries take 2 weeks to develop an endpoint, and distal injuries require 4 to 5 weeks of serial casting. Casting usually allows the PCL to heal with a good endpoint on posterior drawer examination. This treatment approach usually results in no medial laxity, acceptable posterior laxity, and ACL deficiency. Once the MCL has healed, rehabilitation is begun to restore normal knee range of motion. By this time, the patient’s knee should be calm and the physician can perform a reevaluation of ACL and PCL stability. Sometimes the ACL and PCL stability will be sufficient to totally avoid surgery. Most of the time, PCL laxity will have improved and be 2þ or less. In a prospective natural history study of patients with acute isolated PCL injuries, the outcome of patients with 1þ PCL laxity did not have better overall subjective, objective, or radiographic results than patients with 2þ PCL laxity.22 Additionally, current surgical techniques have failed to reproducibly restore normal PCL 481

Anterior Cruciate Ligament Reconstruction stability.50,51 Therefore surgery to reduce PCL laxity from 2þ to 1þ should not allow improved function or less development of degenerative changes. Until operative techniques can reliably obtain normal PCL stability, and given that 1þ posterior laxity has not been shown to provide better function than 2þ laxity, we recommend nonoperative treatment of PCL laxity of 2þ or less. Depending on the patient’s activity level and athletic goals, an ACL reconstruction may be warranted. In some patients, this approach also allows for healing of the ACL, which may provide enough stability to allow patients to do well functionally without having the ACL reconstructed. Only rarely will PCL laxity be greater than 2þ on posterior drawer testing (the tibia sits behind the femoral condyles). When the patient’s knee has 3þ PCL laxity and increased recurvatum is present, semi-acute (7 to 10 days) PCL reconstruction may be indicated to optimize long-term results, although the author has rarely seen this in practice. It is possible that 3þ laxity observed at the time of the acute injury may decrease with a follow-up examination several days or weeks later. The decision to perform a PCL reconstruction should not be based on the findings of the MRI. As stated previously, even with other ligamentous damage, the PCL can heal with continuity. A subsequent physical examination to evaluate PCL laxity is certainly simpler than surgery, and even when the lateral side is involved, the physician has 1 week to 10 days to let the knee calm down to allow for a more accurate physical examination of ligamentous laxity. We do not recommend a combined ACL/PCL reconstruction be performed acutely because of the high incidence of knee stiffness.52–55 If a PCL reconstruction is indicated, the reconstruction should be delayed until the knee has little swelling and good range of motion and the patient has good leg control. Additionally an antiembolism stocking and continuous passive range of motion device can be used to prepare the patient for surgery. To further reduce operative trauma, we prefer using autogenous patellar tendon graft from the contralateral knee. If ACL deficiency becomes symptomatic, an ACL reconstruction can be performed electively at a later date. When high-grade MCL laxity is present and fails to heal with the previously described treatment plan, a number of options are available. Multiple longitudinal perforations in the MCL can be done to stimulate healing. We have found this useful in tightening the medial side without compromising postoperative range of motion. Additional options include recessing the femoral attachment, advancing the distal attachment, and reefing the MCL, all of which will retension the MCL.56–58

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Combined Anterior Cruciate Ligament, Posterior Cruciate Ligament, and LateralSide Knee Injury A lateral side knee injury requires semi-urgent treatment. We strive to balance being able to obtain range of motion and decrease swelling with the ability to repair the torn lateral structures. The torn lateral structures retract proximally and begin to heal en masse within 3 weeks after injury (Fig. 61-3). Some surgeons advise to dissect and repair individual structures.59,60 We prefer to reattach the en masse tissue versus dissecting out each torn structure to take advantage of the body’s healing reaction from the injury.21 This approach is similar to that described by Aglietti et al.56

Lateral-Side Repair If an ACL or PCL reconstruction is being performed at the same surgical setting as the lateral-side repair, the reconstruction should be performed before the lateral-side repair. A longitudinal skin incision is made laterally from distal to proximal between the tibial tubercle and fibular head. A pseudomembrane forms over the injured structures when the surgery is performed within 3 weeks of the injury. The underlying structures can be identified once the pseudomembrane is entered. The iliotibial band is usually intact, and the injured structures begin just posterior to the iliotibial band where the lateral capsule attaches to the tibia. A bare area of bone will be exposed on the proximal lateral tibia and fibular head because of the injury. The bare area is easily exposed with blunt finger dissection. The retracted tissue that has healed en masse can be easily seen. The tissue, instead of being dissected into individual structures, is left en masse

FIG. 61-3 Intraoperative picture showing the lateral capsule tear off the tibia.

Anterior Cruciate Ligament Injury Combined with Medial Collateral Ligament, Posterior Cruciate Ligament, and/or Lateral-Side Injury and repaired back to the lateral capsule attachment site.21 An Ethibond (Ethicon, Somerville, NJ) suture is passed through the tissue mass by using a modified Kesslar stitch. One suture is passed anteriorly, and another is passed posteriorly. The bony attachment site on the tibia is freshened with a curette or bur. A suture anchor is placed if repair to the fibular head is also required. The mass of tissue is advanced to the normal capsular attachment site and fixed with a stable (Fig. 61-4). If the injury is older than 3 weeks and the tissue is friable, then a screw and soft tissue washer are used for secure fixation. The avulsed biceps femoris tendon and lateral collateral ligament are reattached to the fibula with a suture anchor or reattached to a cuff of remaining soft tissue. After repair, the knee is moved from 0 degrees of extension to at least 90 degrees of flexion or more until the lateral repair becomes taut. A drain is placed subcutaneously, and the subcutaneous wound is closed with Vicryl (Ethicon). The superficial wound is closed with staples or sutures. To control knee and leg swelling, an antiembolism stocking, cold/compression device, and immobilizer are placed on the leg.

but are required to wear the immobilizer for 1 to 2 weeks postoperatively, when good quadriceps muscle control is usually achieved. The rehabilitation process is similar to the rehabilitation after ACL reconstruction.61 Patients must obtain full knee range of motion equal to the contralateral knee, good leg control, and a normal gait before beginning aggressive strengthening exercises. The return to activities is individualized to each patient’s goals and lifestyle.

Postoperative Rehabilitation


Medial-side knee injuries can heal with proper

The patient remains in bed with the operative leg in a continuous passive motion (CPM) machine for the first week after surgery. The continuous passive motion machine is set to move from 0 degrees of extension to 30 degrees of flexion. The patient performs specific range of motion exercises 4 to 5 times a day to increase extension and flexion in the knee. If the lateral gastrocnemius muscle was intact, then full extension is allowed; if the muscle was injured, then extension is limited to 0 degrees for 3 to 4 weeks to allow healing. Patients are allowed to weight bear as able

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SUMMARY Acute surgery in patients with combined ligament injuries of the knee can lead to stiffness, primarily with medial-side injuries. All knee dislocations should not be grouped together because of the difference in healing potential between medial- and lateral-side injuries. Our approach is based on the individual healing potential of the injured structures, and the natural history of these injuries. This algorithm is based on the following:


Appropriate treatment to provide MCL or lateral-side stability is key. nonoperative treatment to include firm immobilization (recommend casting). Distal MCL injuries take longer to heal than proximal MCL injuries.


PCL tears can heal even in combination with other ligament injuries; therefore surgery is not usually indicated. Given that PCL laxity of 2þ or less has not been shown to be predictive of long-term results, acute PCL reconstruction is not indicated.


ACL injuries, in general, do not heal. The ACL injury in combination with MCL and/or PCL injury can initially be treated nonoperatively and reconstructed later as dictated by patient symptoms and activity level.


Lateral-side knee injuries do not heal and require semiacute surgery. Individual lateral structures do not need to be dissected out for repair. The en masse tissue formed after the injury can be repaired by attaching it to the lateral capsule attachment site on the tibia.

References

FIG. 61-4 The lateral capsule is repaired back to the area of the avulsion from the tibia just posterior to Gerdy’s tubercle.

1. Good L, Johnson RJ. The dislocated knee. J Am Acad Orthop Surg 1995;3:284–292. 2. Wascher DC, Dvirnak PC, DeCoster TA. Knee dislocation: initial assessment and implications for treatment. J Orthop Trauma 1997;11:525–529. 3. Bratt HD, Newman AP. Complete dislocation of the knee without disruption of both cruciate ligaments. J Trauma 1993;34:383–389. 4. Cooper DE, Speer KP, Wickiewicz TL, et al. Complete knee dislocation without posterior cruciate ligament disruption: a report of four cases and review of the literature. Clin Orthop 1992;284:228–233.

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Anterior Cruciate Ligament Reconstruction 5. Shelbourne KD, Pritchard J, Rettig AC, et al. Knee dislocations with intact PCL. Orthop Rev 1992;21:607–611. 6. Kannus P, Jarvinen M. Non-operative treatment of acute knee ligament injuries. Am J Sports Med 1990;9:244–260. 7. Treiman GS, Yellin AE, Weaver FA, et al. Examination of the patient with a knee dislocation: the case for selective arteriography. Arch Surg 1992;127:1056–1061. 8. Walker DN, Hardison RR, Schenck RC. A baker’s dozen of knee dislocations. Am J Knee Surg 1994;7:117–124. 9. Shelbourne KD, Carr DR. Combined anterior and posterior cruciate and medial collateral ligament injury: nonsurgical and delayed surgical treatment. Instr Course Lect 2003;52:413–418. 10. Kennedy JC. Complete dislocation of the knee joint. J Bone Joint Surg 1963;45A:889–904. 11. Sisto DJ, Warren RF. Complete knee dislocation. A follow-up study of operative treatment. Clin Orthop 1985;198:94–101. 12. Hefti FL, Kress A, Fasel J, et al. Healing of transacted anterior cruciate ligament in the rabbit. J Bone Joint Surg 1991;73A:373–383. 13. Lyon RM, Akeson WH, Amiel D, et al. Ultrastructural differences between the cells of the medial collateral and anterior cruciate ligaments. Clin Orthop 1991;272:279–286. 14. McDaniel WJ Jr, Dameron TB Jr. Untreated anterior ruptures of the cruciate ligament: a follow-up study. J Bone Joint Surg 1980;62A:310–322. 15. Warren RF, Marshall JL. Injuries of the anterior cruciate and medial collateral ligaments of the knee: a long term follow-up of 86 cases. Part II. Clin Orthop 1978;136:197–211. 16. Yao L, Gentili A, Petrus L, et al. Partial ACL rupture: an MRI diagnosis. Skeletal Radiol 1995;24:247–251. 17. Fischer SP, Fox JM, Del Pizzo W, et al. Accuracy of diagnosis from magnetic resonance imaging of the knee. A multicenter analysis of 1014 patients. J Bone Joint Surg 1991;73A:2–10. 18. Polly DW Jr, Callaghan JJ, Sikes RA, et al. The accuracy of selective magnetic resonance imaging compared with the findings of arthroscopy of the knee. J Bone Joint Surg 1988;70A:192–198. 19. Shelbourne KD, Jennings RW, Vahey TN. Magnetic resonance imaging of posterior cruciate ligament injuries: assessment of healing. Am J Knee Surg 1999;12:209–213. 20. Tewes DP, Fritts HM, Fields RD, et al. Chronically injured posterior cruciate ligament. Magnetic resonance imaging. Clin Orthop 1997;335:224–232. 21. Shelbourne KD, Haro MS, Grag T. Knee dislocation with lateral side injury: Results of an En Masse Surgical repair technique of the lateral side. Am J Sports Med 2007;35:1005–1117. 22. Shelbourne KD, Davis TJ, Patel DV. The natural history of acute isolated non-operatively treated posterior cruciate ligament injuries. A prospective study. Am J Sports Med 1999;27:276–283. 23. Anderson DR, Weiss JA, Takai S, et al. Healing of the medial collateral ligament following a triad injury: a biomechanical and histologic study of the knee in rabbits. J Orthop Res 1992;10:485–495. 24. Woo SLY, Inoue M, McGurk-Burleson E, et al. Treatment of the medial collateral ligament injury: II. Structure and function of canine knees in response to differing treatment regimes. Am J Sports Med 1987;15:22–29. 25. Fetto JF, Marchall JL. Medial collateral ligament injuries of the knee. Clin Orthop 1978;132:206–218. 26. Petermann J, von Garrel T, Gotzen L. Non-operative treatment of acute medial collateral ligament lesions of the knee joint. Knee Surg Sports Traumatol Arthrosc 1993;1:93–96. 27. Clayton ML, Miles JS, Abdulla M. Experimental investigations of ligamentous healing. Clin Orthop 1968;61:146–153. 28. Tipton CM, Vailas AC, Matfhes RD. Experimental studies on influence of physical activity on ligaments, tendons and joints: a brief report. Acta Med Scand Suppl 1986;711:157–168. 29. Amiel D, Akeson WH, Harwood FL, et al. Stress deprivation effect on metabolic turnover of the medial collateral ligament collagen. A comparison between 9- and 12-week immobilization. Clin Orthop 1983;172:265–270.

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30. Woo SLY, Horibe S, Ohland KJ, et al. The response of ligaments to injury. Healing of the collateral ligaments. In Daniel DM (ed). Knee ligaments: structure, function, injury and repair. New York, 1990, Raven Press, pp 351–364. 31. Long ML, Frank C, Schachar NS. The effects of motion on normal and healing ligaments. Trans Orthop Res Soc 1982;7:43. 32. DeLee JC, Riley MB, Rockwood CA. Acute straight lateral instability of the knee. Am J Sports Med 1983;11:404–411. 33. Robins AJ, Newman AP, Burks RT. Postoperative return of motion in anterior cruciate ligament and medial collateral ligament injuries. The effect of medial collateral ligament rupture location. Am J Sports Med 1993;21:20–25. 34. Jonsson T, Althoff B, Peterson L, et al. Clinical diagnosis of ruptures of the anterior cruciate ligament: a comparative study of the Lachman test and the anterior drawer sign. Am J Sports Med 1982;10:100–102. 35. Torg JS, Conrad W, Kalen V. Clinical diagnosis of anterior cruciate ligament instability in the athlete. Am J Sports Med 1976;4:84–93. 36. Clancy WG, Shelbourne KD, Zoellner GB, et al. Treatment of knee joint instability secondary to rupture of the posterior cruciate ligament. Report of a new procedure. J Bone Joint Surg 1983;65A:310–322. 37. Insall JN, Hood RW. Bone block transfer of the medial head of the gastrocnemius for posterior cruciate insufficiency. J Bone Joint Surg 1982;64A:691–699. 38. Hughston JC, Andrews JR, Cross MJ, et al. Classification of knee ligament instabilities. Part I: the medial compartment and cruciate ligaments. J Bone Joint Surg 1976;58A:159–172. 39. Rubinstein RA Jr, Shelbourne KD, McCarroll FR, et al. The accuracy of the clinical examination in the setting of the posterior cruciate ligament injuries. Am J Sports Med 1994;22:550–557. 40. Grood ES, Noyes FR, Butler DL, et al. Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg 1981;63A:1257–1269. 41. Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg 1977;59A:236–239. 42. Shelbourne KD, Porter DA, Clingman JA, et al. Low velocity knee dislocation. Orthop Rev 1991;20:995–1004. 43. Shelbourne KD, Klootwyk TE. Low-velocity knee dislocation with sports injuries. Treatment principles. Clin Sports Med 2000;19:443–456. 44. Merchant AC, Mercer RL, Jocobsen RH, et al. Roentgenographic analysis of patellofemoral congruence. J Bone Joint Surg 1975;56A:1391–1396. 45. Rosenberg TD, Paulos LE, Parker RD, et al. The forty-five-degree posteroanterior flexion weight-bearing radiograph of the knee. J Bone Joint Surg 1988;70A:1479–1483. 46. Meyers MH, Harvey JP. Traumatic dislocation of the knee joint: a study of eighteen cases. J Bone Joint Surg 1971;53A:16–29. 47. Almekinders LC, Logan TC. Results following treatment of traumatic dislocations of the knee joint. Clin Orthop 1992;284:203–207. 48. Dedmond BT, Almekinders LC. Operative versus nonoperative treatment of knee dislocations. A meta-analysis. Am J Knee Surg 2001;14:33–38. 49. Frassica FJ, Sim FH, Staeheli JW, et al. Dislocation of the knee. Clin Orthop 1991;263:200–205. 50. L’Insalata JC, Harner CD. Treatment of acute and chronic posterior cruciate ligament deficiency: new approaches. Am J Knee Surg 1996;9:185–193. 51. Noyes FR, Barber-Westin SD. Treatment of complex injuries involving the posterior cruciate and posterolateral ligaments of the knee. Am J Knee Surg 1996;9:200–214. 52. Harner CD, Irrgang JJ, Paul J, et al. Loss of motion after anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:449–506. 53. Mohtadi NGH, Webster-Bogaert S, Fowler PJ. Limitation of motion following anterior cruciate ligament reconstruction. A case-control study. Am J Sports Med 1991;19:620–625. 54. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292–299. 55. Shelbourne KD, Wilckens JH, Mollabashy A, et al. Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation. Am J Sports Med 1991;19:332–336.

Anterior Cruciate Ligament Injury Combined with Medial Collateral Ligament, Posterior Cruciate Ligament, and/or Lateral-Side Injury 56. Aglietti P, Zaccherotti G, DeBiase P. Combined knee ligament injuries. In Tria AJ (ed). Ligaments of the knee. New York, 1995, Churchill Livingstone, pp 207–259. 57. Maynard MJ, Warren RF. Surgical and reconstructive technique for knee dislocation. In Jackson DW (ed). Techniques in orthopaedic surgery—reconstructive knee surgery. New York, 1995, Raven Press, pp 161–183. 58. Stroud CC, Reider B. Medial and posteromedial ligament injuries of the knee. In Garrett WE, Speer KP, Kirkendall DT (eds). Principles and practice of orthopaedic sports medicine. Baltimore, 2000, Lippincott, Williams & Wilkins, pp 663–674. 59. Harner CD, Waltrip RL, Bennett CH, et al. Surgical management of knee dislocations. J Bone Joint Surg 2004;86A:262–273.

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60. Kurtz CA, Sekiya JK. Treatment of acute and chronic anterior cruciate ligament-posterior cruciate ligament-lateral side knee injuries. J Knee Surg 2005;18:228–239. 61. Shelbourne KD, Gray T. Anterior cruciate ligament reconstruction with autogenous patellar tendon graft followed by accelerated rehabilitation. A two- to nine-year followup. Am J Sports Med 1997;25:786–795.

Suggested Reading Hughston JC, Bowden JA, Andrews JR, et al. Acute tears of the posterior cruciate ligament. Results of operative treatment. J Bone Joint Surg 1980;62A:438–450.

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62 CHAPTER

K. Donald Shelbourne Tinker Gray

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Treatment of Meniscus Tears with Anterior Cruciate Ligament Reconstruction INTRODUCTION The treatment of meniscus tears in conjunction with anterior cruciate ligament (ACL) reconstruction requires a thorough understanding of the different types of meniscus tears and their capacity for healing. The factors to consider are whether the tear is medial or lateral, degenerative or nondegenerative, or stable or unstable, as well as the vascular zone of the meniscus. The treatment choices are to remove, repair, or leave the tear in situ. Meniscus tears with ACL injuries are different than meniscus tears in ACL intact knees. For a meniscus to tear, either (1) the knee is unstable, causing excessive movement, which in turn causes the meniscus to become caught between the femur and the tibia or (2) the knee is stable, and the meniscus has a degenerative component to it. In general, meniscus tears in ACL intact knees have extensive degeneration. Meniscus tears with an acute ACL injury are traumatic and occur mostly in the posterior and peripheral part of the meniscus. Meniscus tears in chronic ACL deficient knees can be degenerative or nondegenerative, depending on the number and severity of instability episodes. The incidence of lateral meniscus tears has been reported to be higher than the incidence of medial meniscus tears with acute ACL injuries.1 Shelbourne and Gray2 found that of 448 patients with acute ACL injuries, 62% had lateral meniscus tears and 42% had medial meniscus tears, whereas in 609 patients with chronic ACL

deficiency, 49% had lateral meniscus tears and 60% had medial meniscus tears. Cipolla et al3 found that of 218 acute injuries, 59% had lateral meniscus tears and 28.5% had medial meniscus tears, whereas in 552 chronic ACL injuries, 41.6% had lateral meniscus tears and 74% had medial meniscus tears. The lateral meniscus is mobile and translates 9 to 11 mm in the anteroposterior plane, whereas the medial meniscus translates only 2 to 5 mm.4 The lateral meniscus is more frequently injured acutely because of its extreme mobility, and the peripheral and posterior portions of the meniscus are prone to getting caught in the joint during an ACL instability episode, which may explain the high incidence of posterior horn avulsion tears with acute ACL injuries. The less mobile medial meniscus is less injured with acute ACL injuries, and it may take consecutive giving-way episodes for the peripheral posterior third of the meniscus to become caught in the joint. When patients do have a medial meniscus tear with an acute ACL injury, it is typically a peripheral vertical tear in the posterior third of the meniscus. This tear can extend anteriorly with additional giving-way episodes and eventually become a bucket-handle tear. The fact that more lateral meniscus tears are seen with acute ACL injuries than with chronic ACL deficiency can be explained by the fact that most lateral meniscus tears with acute ACL injuries can heal without treatment. In fact, many medial meniscus tears seen at the time of acute ACL reconstruction can heal without repair. With the advent of knee

Treatment of Meniscus Tears with Anterior Cruciate Ligament Reconstruction arthroscopy, surgeons have felt compelled to treat many meniscus tears seen at the time of ACL reconstruction that would have been unobserved and left alone before knee arthroscopy was invented. The high meniscus repair success rate with ACL reconstruction can partially be explained by the fact that many menisci are being repaired that probably do not need any treatment at all. This chapter will discuss the types of meniscus tears seen with ACL reconstruction, which meniscal tears can be left in situ, which tears to repair and the repair success rates, and finally the timing of meniscus repair with ACL reconstruction surgery.

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the almost 100% success with repair of lateral meniscus tears and came to the conclusion that many of the lateral meniscus tears being repaired probably did not need repair. Therefore the senior author began to change his treatment of lateral meniscus tears from repairing 80% of the tears in 1984 to repairing 15% in 1992. During that same time, he changed his treatment from leaving lateral meniscus tears in situ in 4% of tears in 1984 to 70% in 1992. The types of lateral meniscus tears left alone included posterior horn avulsions (52 tears; Fig. 62-1), stable vertical tears that were posterior to the popliteus tendon (99 tears; Fig. 62-2), and nondisplaced vertical tears that extended anterior to the popliteus tendon (27 tears).10 With a follow-up at a mean of 2.6 years

MENISCUS TEARS TO LEAVE IN SITU With acute ACL injuries, most meniscus tears are not symptomatic for the patient. The patient’s inability to fully extend the knee is usually due to the ACL stump being lodged in the intercondylar notch. Shelbourne et al5 found that joint line tenderness observed at the time of acute ACL injury does not correlate to the presence or absence of meniscus tears at the time of surgery. Over a 2-year period, 173 patients were seen for acute injury and were evaluated for joint line tenderness, and then the type of meniscus tear was recorded at the time of surgery. The investigators found that medial joint line tenderness was 45% sensitive and 34% specific for a medial meniscus tear. Lateral joint line tenderness was 58% sensitive and 49% specific for a lateral meniscus tear.5 We now delay ACL surgery until the patient’s knee has full range of motion and no swelling and the patient has good leg control. On the day of surgery, very few patients have joint line tenderness but about 50% have a meniscus tear.6 It appears that meniscus injuries in conjunction with acute ACL injuries are difficult to determine preoperatively based on joint line tenderness exam. The meniscus has a blood supply provided by the perimeniscal capillary plexus, and these capillaries extend into 20% to 30% of the body of the medial meniscus and 10% to 25% of the lateral meniscus.7,8 Tears in the peripheral vascular zone of the meniscus are thought to be ideal for meniscus repair, but many can heal without specific repair treatment. The acuteness or chronicity of the ACL injury is not the deciding factor for determining the treatment of the meniscus. Rather, it is the location of the tear and the degenerative nature of the tear that help determine treatment.

FIG. 62-1 Posterior horn avulsion tear of the lateral meniscus commonly seen with acute anterior cruciate ligament (ACL) injuries.

Lateral Meniscus Tears Complete removal of a torn lateral meniscus has a poor prognosis.9 In the early 1980s, the senior author observed

FIG. 62-2 Superior surface of the lateral meniscus, showing a stable vertical tear.

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Anterior Cruciate Ligament Reconstruction (range 1–9 years), Fitzgibbons and Shelbourne10 found that no patients returned to the clinic reporting symptoms of a lateral meniscus tear. One patient twisted his knee playing basketball at 114 days after ACL reconstruction and had a displaced bucket-handle medial meniscus tear. At the time of follow-up arthroscopy, the original vertical lateral meniscus tear had progressed to a complex T-type tear, but the tear did not extend anterior to the popliteus. Shelbourne and Heinrich11 performed another longterm follow-up of 332 patients who had lateral meniscus tears left in situ or treated with abrasion and trephination without suture repair. The patients also had no medial meniscus tears or chondromalacia greater than grade II to isolate the factor of lateral meniscus tears in the long-term follow-up analysis. At a mean of 5.1 years after surgery, 162 patients (95%) had normal radiographs, six patients had nearly normal radiographs, and two patients had abnormal radiographs for lateral joint space narrowing using IKDC criteria. Of 70 patients with posterior horn avulsion tears left in situ, two (2.9%) underwent a subsequent procedure to remove the tear. Of 50 patients with radial flap tears, three patients (6%) needed a subsequent surgery for the tear. Of 169 patients with peripheral or posterior tears left in situ, three patients (1.8%) required subsequent surgery for the tear. None of the 43 patients who had peripheral or posterior tears treated with abrasion and trephination required further surgery.11

Medial Meniscus Tears Medial meniscus tears seen at the time of acute ACL reconstruction are traumatic in nature and are usually in the vascular zone of the meniscus. A common type of tear seen with acute ACL injury is a peripheral or posterior stable medial meniscus tear, which can be easily missed (Fig. 62-3). This type of tear is not symptomatic for the patient, and it is possible that many of these tears heal on their own in patients who do not undergo an ACL reconstruction acutely or semi-acutely. Shelbourne and Rask12 performed a follow-up study to determine the outcome of nondegenerative peripheral vertical medial meniscus tears that were stable and were treated either by leaving the tear in situ or with abrasion and trephination without suture repair. All the tears were greater than 1 cm long but could not be displaced into the intercondylar notch. Between 1982 and 1988, 139 tears were treated by leaving the tears in situ. Between 1989 and 1997, the tears were treated with abrasion and trephination. At a mean of 4.8 years after surgery, the number of patients who underwent subsequent arthroscopy for symptoms of a meniscus tear was 15 (10.8%) for the tears left in situ and 14 (6%) for the tears treated with abrasion and trephination. The mean time after ACL reconstruction that 488

FIG. 62-3 Inferior surface of the medial meniscus, showing a peripheral vertical posterior third tear commonly seen with acute anterior cruciate ligament (ACL) injuries.

patients experienced symptoms was 2.5 years for the tears left in situ and 2.3 years for the tears treated with abrasion and trephination. As part of the same study, 176 patients had the same type of meniscus tear, but it was unstable and required suture repair. The failure rate of the repaired group was 13.6%.12 Trephination has been shown in both animal and clinical studies to enhance meniscal healing by creating vascular channels.13–15 Fox et al16 treated 26 incomplete peripheral vertical meniscus tears by trephination alone and had 90% clinical success, but all of the tears were less than 1 cm long. Weiss et al17 showed that medial meniscus tears of 1 cm or less can heal if left alone, but the study did not evaluate tears greater than 1 cm long. It is accepted that peripheral vertical medial meniscus tears less than 1 cm long that are found at the time of ACL reconstruction can be left in situ or treated with trephination. Shelbourne and Rask12 have now shown that tears longer than 1 cm long can also be left in situ or treated with trephination and still have a very low rate of causing subsequent symptoms of a meniscus tear. Trephination is a simple technique to provide vascular channels in the meniscus for healing, and it avoids the risks associated with meniscus repair using sutures.

MENISCUS TEARS TO REPAIR It would be ideal to attempt to repair all torn menisci because the menisci transmit load across the medial and lateral compartments of the knee. As more of the meniscus is removed, the more contact surface between the femur and

Treatment of Meniscus Tears with Anterior Cruciate Ligament Reconstruction tibia is lost and contact stress increases. Meniscus repair of all menisci, however, does not ensure that the repaired meniscus performs normally for distributing load and absorbing stress. McCarty et al18 published an extensive review of the different types of meniscus repair techniques and their results. It appears that most techniques can be successful, with rates ranging from 73% to 99% for clinical success and 25% to 90% for success of meniscal healing. The factors for success were similar for the different types of repairs: success was dependent on meniscus tear type, size, and location. To determine the success of meniscus repair, it would be most helpful for investigators to study specific types of meniscus tears instead of combining all types together. Cannon and Vittori13 evaluated meniscal healing in 90 repairs done in conjunction with ACL reconstruction and 27 repairs in ACL intact knees, and the healing was related to rim width (vascular versus avascular zones), tear length (stable versus unstable), and joint compartment (lateral versus medial). Rim widths up to 2 mm had a healing success rate of 96%. Rim widths of 2 to 4 mm had a healing success rate of 84%, and rim widths of 4 to 5 mm had a success rate of 50%. Tear length less than 2 cm had a 94% success rate, and tear lengths of 2 to 4 cm had an 86% success rate. When the tear length was more than 4 cm, the healing rate was only 50%. Lateral meniscus tears successfully healed 93% of the time, whereas medial meniscus tears healed 73% of the time. Meniscus repair done with ACL reconstruction was more successful (93%) than repairs done in ACL intact knees (50% success), but there was no information provided as to the differences in rim width, tear length, or joint compartment between the two groups.13 Asahina et al19 also evaluated the factors that affected healing of meniscal repair of unstable, full-thickness, vertical, longitudinal tears longer than 15 mm in 98 patients evaluated by second-look arthroscopy. Of the 98 repairs, 73 completely healed, 13 incompletely healed, and 12 did not heal. Healing was achieved in 78% of medial meniscus repairs and 63% of lateral meniscus repairs. Repairs in the peripheral third zone had a statistically significant better healing rate of 87%, compared with 59% for repairs in the central third zone. The statistically significant factors in healing were rim width and meniscal locking. Meniscus tears in the central third zone that had been locked in the knee or could be locked at the time of surgery had a negative correlation to healing.19 Unstable meniscus tears, such as bucket-handle tears, are common with chronic ACL instability (Fig. 62-4). Most bucket-handle meniscus tears are degenerative, which is why they are very seldom seen with acute ACL injuries. It is possible for a bucket-handle tear to be nondegenerative in a patient with chronic ACL laxity if he or she has been able to

62

protect the knee from instability episodes and has just suffered a recent giving-way episode prior to the evaluation. In a series of 55 bucket-handle meniscus tears seen with chronic ACL deficiency, 43 tears (78%) were in the white-white nonvascular zone of the meniscus, 11 were in the red-white vascular zone, and one was in the red-red vascular zone.20 O’Shea and Shelbourne20 evaluated meniscal healing of repairs done on bucket-handle meniscus tears that were unstable and locked in the intercondylar notch in patients with chronic ACL deficiency. Patients underwent meniscus repair followed by rehabilitation to regain full knee range of motion, strength, and function before undergoing an ACL reconstruction at a later date. The menisci were evaluated with arthroscopy at the time of the ACL reconstruction, which occurred at a mean of 77 days after meniscus repair. Of 43 repairs done in the avascular zone of the meniscus, only five menisci showed no healing at the repair site. Of 11 repairs done in the red-white vascular zone of the meniscus, only one repair showed no healing. The one repair done in the red-red zone of the meniscus healed completely. At a subsequent follow-up at a mean of 4.3 years after repair, four patients had a failed repair that required subsequent arthroscopies to remove repairs done in the avascular zone of the meniscus (Fig. 62-5). Rubman et al21 found similar success rates of meniscal repair in 198 meniscus tears that had a rim width of 4 mm or more. Most of the tears were either single (N ¼ 92) or double (N ¼ 40) longitudinal tears. Clinical success, defined as the patient being asymptomatic for tibiofemoral joint symptoms, was found in 80%. Arthroscopic follow-up evaluation of 91 of the tears found that 23 (25%) had completely healed, 35 (38%) had partially healed, and 33 (36%) failed. The authors concluded that repairs of the meniscus in the avascular zone is preferred over partial meniscectomy, especially in young athletic patients or patients with varus or valgus lower extremity malalignment. Noyes and BarberWestin22 in a similar study found that 26 of 33 repairs of tears in the avascular zone remained asymptomatic at a mean of 33 months postoperatively for patients 40 years or older. Thus it appears that meniscus tears, even in the avascular zone of the meniscus, can heal or remain asymptomatic with repair. The question remains as to whether repaired menisci, especially large bucket-handle tears in the avascular zone, function well enough to protect the joint and not cause symptoms for the patient in the long term. Shelbourne and Carr23 compared the results of meniscus repair versus partial meniscectomy of bucket-handle medial meniscus tears in ACL reconstructed knees. The patients had no other intraarticular pathology such as lateral meniscus tears or articular cartilage damage greater than Outerbridge grade 2. One would expect that patients who underwent meniscus repair would have better results than 489

Anterior Cruciate Ligament Reconstruction

FIG. 62-4 Bucket-handle medial meniscus tear. A, Superior surface of the medial meniscus tear, showing the bucket-handle separation. B, Inferior surface of the tear being trephinated. C, Meniscus after repair with sutures.

patients who had a partial meniscectomy. The mean modified Noyes subjective score was identical for the two groups, 90.9 points, at 8 years after surgery. Of note, however, was that when the repair group was analyzed based on whether the bucket-handle tear was degenerative or nondegenerative, patients who had a degenerative meniscus tear had a mean score of 87.1 points, which was statistically significantly lower than the mean of 93.9 points for patients who had a nondegenerative meniscus tear. Radiographic evaluation showed that 11 of 12 patients (92%) in the nondegenerative group had normal radiographs at follow-up versus only nine of 12 patients (75%) in the degenerative group. Interestingly, 41 of 52 patients (79%) who had partial meniscectomy of the bucket-handle tear also had normal radiographs. Therefore the authors concluded that repaired 490

degenerative bucket-handle medial meniscus tears may not function normally in the knee to provide any advantage over partial meniscectomy.23 In a similar study, Shelbourne and Dersam24 compared the results of partial meniscectomy versus repair for bucket-handle lateral meniscus tears with ACL reconstruction. The patients had no other intraarticular pathology, such as medial meniscus tears or articular cartilage damage greater than Outerbridge grade 2. The mean time of subjective follow-up was 7 years for the repair group and 11 years for the removal group. The mean total subjective score for 57 patients in the repair group was 92.5 points, and the mean total score for the removal group was 88.7 points, which was not statistically significantly different. Patients in the removal group did have statistically significantly lower

Treatment of Meniscus Tears with Anterior Cruciate Ligament Reconstruction

62

FIG. 62-5 Meniscus at 3 months after repair of bucket-handle tear. No sutures are present, and the meniscus appears healed on the superior surface (A) and inferior surface (B).

pain subscores on the subjective survey than patients in the repair group. Radiographic evaluation using IKDC criteria found that 83% of the removal group (8 years postoperatively) and 87% of the repair group (6 years postoperatively) had normal radiographs. The longer follow-up time for the removal group should have accentuated any detriment of meniscus removal of the tears versus meniscus repair. Although the subjective scores between groups were not statistically significantly different, we believe the P value of 0.2014 indicates a trend toward lower scores in the removal group.24

Timing of Meniscus Repair with Anterior Cruciate Ligament Surgery There is one situation in which meniscus repair should not be performed at the same time as ACL reconstruction. Patients who have chronic ACL deficiency commonly seek treatment when they suffer a meniscus tear that is causing clicking, locking, or pain in the knee. Sometimes the common bucket-handle tear seen with chronic ACL instability will become locked in the intercondylar notch. When patients seek treatment, they want treatment for the immediate problem of the meniscus tear and may not be prepared mentally or socially to undergo an ACL reconstruction. Furthermore, there is a higher risk of arthrofibrosis when the patient undergoes ACL reconstruction when the knee does not have full range of motion equal to the opposite normal knee.25 Shelbourne and Johnson26 found a higher incidence of arthrofibrosis in patients who underwent meniscus repair or removal of a locked bucket-handle meniscus tear in conjunction with ACL reconstruction versus patients who

underwent staged procedures of meniscus repair or removal, rehabilitation to restore normal knee motion, and ACL reconstruction at a later date. Four of 16 patients who underwent meniscus treatment and ACL reconstruction suffered arthrofibrosis, compared with 0 of 16 patients who underwent staged procedures. All of the patients had flexion contractures of 5 to 20 degrees with the locked bucket-handle meniscus tear, and the mean time that the meniscus was locked in the knee before surgery could be performed was 12.4 days. Loss of knee extension is a common complication after ACL reconstruction. It is more commonly associated with ACL reconstruction after acute injury versus chronic instability, but any loss of normal knee extension to include normal hyperextension affects the long-term results after surgery. In a 10- to 20-year follow-up study of ACL reconstruction, any loss of normal knee extension or flexion after surgery was the most important factor related to lower subjective scores. Another significant factor considered in the regression analysis was partial medial or lateral meniscectomy, but any loss of knee motion was more important.27 Although it is certainly possible to perform combined ACL reconstruction with treatment for a locked buckethandle meniscus tear in a chronic ACL deficient knee and achieve normal knee range of motion, our philosophy for treatment is to approach ACL reconstruction in a way that gives the patient the best possible outcome in the long term. The surgery and rehabilitation for ACL reconstruction should be done at a time when it is most convenient for the patient to miss work or school and perform proper rehabilitation. It is difficult to function well with a locked bucket-handle meniscus tear in the knee, and surgery is somewhat of an emergency. 491

Anterior Cruciate Ligament Reconstruction Obtaining full knee range of motion can be difficult for patients even when the only surgery performed is a repair or removal of the locked meniscus, especially if the knee has been locked in flexion for more than 1 or 2 weeks. We believe that staging the treatments for the meniscus tear and ACL deficiency gives the patient the best possible opportunity to obtain full knee range of motion. All other types of meniscus repair can be done effectively in conjunction with ACL reconstruction. It is important that physicians not limit the ACL rehabilitation when a meniscus repair is done at the same time. Exercises to achieve full, symmetrical knee range of motion should begin on the day of surgery, and there is no reason to limit weight bearing. In the study by Shelbourne and Johnson26 in which patients underwent staged procedures for treatment of a locked bucket-handle meniscus tear followed by ACL reconstruction, 14 patients underwent meniscus repair. The rehabilitation allowed unrestricted weight bearing and full knee range of motion, and patients underwent ACL reconstruction at a later date when rehabilitation goals had been achieved. At the time of ACL reconstruction, an arthroscopy was performed to evaluate meniscal healing. The average time of evaluation was 72 days, and all repaired menisci had evidence of healing. Only one patient subsequently had a tear to the repaired meniscus at 18 months after repair. We believe that weight bearing with the knee in full extension pushes the meniscus toward the capsule and may promote healing.26

CONCLUSIONS Not all meniscus tears require a formal repair. Many stable menisci can be left in situ or treated with trephination to create vascular channels for healing. The surgeon must consider what would happen to the torn meniscus if arthroscopic evaluation of the knee were not done at the time of ACL reconstruction. Although degenerative medial meniscus tears in the avascular zone can heal, they may not function normally and may cause a loss of knee range of motion or other adverse symptoms for patients.

References 1. Bellabara C, Bush-Joseph CA, Bach BR Jr. Patterns of meniscal injury in the anterior cruciate-deficient knee: a review of the literature. Am J Orthop 1997;26:18–23. 2. Shelbourne KD, Gray T. Anterior cruciate ligament reconstruction with autogenous patellar tendon graft followed by accelerated rehabilitation: a two- to nine-year followup. Am J Sports Med 1997;25:786–795. 3. Cipolla M, Scala A, Gianni E, et al. Different patterns of meniscal tears in acute anterior cruciate ligament (ACL) ruptures and in chronic ACL-deficient knees. Knee Surg Sports Traumatol Arthrosc 1995;3:130–134.

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4. Maitra RS, Miller MD, Johnson DL. Meniscal reconstruction. Part I. Indications, techniques, and graft considerations. Am J Orthop 1999;28:213–218. 5. Shelbourne KD, Martini JD, McCarroll JR, et al. Correlation of joint line tenderness and meniscal lesions in patients with acute anterior cruciate ligament tears. Am J Sports Med 1995;23:166–169. 6. Shelbourne KD. Unpublished data, 2006. 7. Arnoczky SP, Warren RF. Microvasculature of the human meniscus. Am J Sports Med 1982;10:90–95. 8. Arnoczky SP, Warren RF. The microvasculature of the meniscus and its response to injury: an experimental study in the dog. Am J Sports Med 1983;11:131–141. 9. Yocum LA, Kerlan RK, Jobe FW, et al. Isolated lateral meniscectomy. A study of twenty-six patients with isolated tears. J Bone Joint Surg 1979;61A:338–342. 10. Fitzgibbons RE, Shelbourne KD. “Aggressive” nontreatment of lateral meniscal tears seen during anterior cruciate ligament reconstruction. Am J Sports Med 1995;23:156–159. 11. Shelbourne KD, Heinrich J. The long-term evaluation of lateral meniscus tears left in situ at the time of anterior cruciate ligament reconstruction. Arthroscopy 2004;20:346–351. 12. Shelbourne KD, Rask BP. The sequelae of salvaged nondegenerative peripheral vertical medial meniscus tears with anterior cruciate ligament reconstruction. Arthroscopy 2001;17:270–274. 13. Cannon WD Jr, Vittori M. The incidence of healing in arthroscopic meniscal repairs in anterior cruciate ligament-reconstructed knees versus stable knees. Am J Sports Med 1992;20:176–181. 14. Zhang Z, Arnold JA, Williams T, et al. Repairs by trephination and suturing of longitudinal injuries in the avascular area of the meniscus in goats. Am J Sports Med 1995;23:35–41. 15. Zhang ZN, Kaiyuan T, Yinkan X, et al. Treatment of longitudinal injuries in avascular area of meniscus in dogs by trephination. Arthroscopy 1988;4:151–159. 16. Fox JM, Rintz KG, Ferkel RD. Trephination of incomplete meniscal tears. Arthroscopy 1993;9:451–455. 17. Weiss CB, Lundberg ML, Hamberg P, et al. Non-operative treatment of meniscal tears. J Bone Joint Surg 1989;71A:811–822. 18. McCarty EC, Marx RG, DeHaven KE. Meniscus repair: considerations in treatment and update of clinical results. Clin Orthop 2002;402:122–134. 19. Asahina S, Muneta T, Yamamoto H. Arthroscopic meniscal repair in conjunction with anterior cruciate ligament reconstruction: factors affecting the healing rate. Arthroscopy 1996;12:541–545. 20. O’Shea JJ, Shelbourne KD. Repair of locked bucket-handle meniscal tears in knees with chronic anterior cruciate ligament deficiency. Am J Sports Med 2003;31:216–220. 21. Rubman MH, Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscal tears that extend into the avascular zone: a review of 198 single and complex tears. Am J Sports Med 1998;26:87–95. 22. Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscus tears extending into the avascular zone with or without anterior cruciate ligament reconstruction in patients 40 years of age and older. Arthroscopy 2000;16:822–829. 23. Shelbourne KD, Carr DR. Meniscal repair compared with meniscectomy for bucket-handle medial meniscal tears in anterior cruciate ligament-reconstructed knees. Am J Sports Med 2003;31:718–723. 24. Shelbourne KD, Dersam MD. Comparison of partial meniscectomy versus meniscus repair for bucket-handle lateral meniscus tears in anterior cruciate ligament reconstructed knees. Arthroscopy 2004;20:581–585. 25. Shelbourne KD, Wilckens JH, Mollabashy A, et al. Arthrofibrosis in acute anterior cruciate ligament reconstruction: the effect of timing of reconstruction and rehabilitation. Am J Sports Med 1991;19:332–336. 26. Shelbourne KD, Johnson GE. Locked bucket-handle meniscal tears in knees with chronic anterior cruciate ligament deficiency. Am J Sports Med 1993;21:779–782. 27. Shelbourne KD. Unpublished data, 2006.

Anterior Cruciate Ligament Reconstruction Combined with High-Tibial Osteotomy, Autologous Chondrocyte Implantation, Microfracture, Osteochondral, and/or Meniscal Allograft Transplantation INTRODUCTION Knees with chronic anterior cruciate ligament (ACL) tears often have degenerative changes. If these changes are severe, cartilage restorative procedures may be necessary in addition to ACL reconstruction (ACLR). The question in such cases is whether to perform the restorative procedures simultaneously with the ACLR. If they are not done simultaneously, the question becomes one of proper sequencing and the necessary time interval between procedures.

INDIVIDUALIZATION Cases requiring combined procedures are inherently complicated. Some patients will need ACLR plus one other restorative procedure, but some patients may need a total of three or four such procedures. Decision-making can be helped by the application of certain principles, which will be discussed later. However, each patient’s individual characteristics should be carefully studied and weighed in decision-making. The patient’s pathology is most important, but work and life circumstances must be carefully considered to avoid disruption to the extent possible.

SURGEON FACTORS The surgeon must also realistically weigh his or her own skill and experience. When in doubt, it is better to sequence procedures than to perform difficult procedures simultaneously with which

the surgeon may have limited experience. Patients generally prefer simultaneity, but this should not be done if it will subject the patient to greater risk of failure.

63 CHAPTER

Chadwick C. Prodromos Brian T. Joyce

SUCCESS RATES In the literature and in our experience, success rates with appropriate combined procedures have been high. Table 63-1 summarizes the relevant literature. Surgery and aftercare must be meticulous. Reimbursement may not be commensurate with the amount of work performed. Not all surgeons will wish to perform these types of procedures. However, if the procedures are satisfactorily performed, and if the patients are carefully chosen, the results can be gratifying.

PATIENT EXPECTATIONS Patients must be counseled that success is by no means guaranteed with these combined procedures. It is important to discuss the possibility of failure and what the next steps would be. We believe that patients who do not comfortably accept the possibility of failure are best served by first seeing other surgeons to receive second opinions.

RESTORATION OF MOTION The overriding concern in preoperative planning is the avoidance of loss of motion as a result 493

Anterior Cruciate Ligament Reconstruction TABLE 63-1 Success Rates For Combined Procedures Author

Year Success Rate

ACLR with OATS Klinger20

2003 81% normal or nearly normal on IKDC

21

1996 10/12 patients had promising response at 2-year follow-up

Bobic

ACLR with ACI Amin8

2006 7/9 patients improved; 2/9 described no improvement

ACLR with MAT Graf12

2004 1/8 patients had nearly normal results; 7/8 had abnormal or severely abnormal on IKDC scale

Sekiya11

2003 86% normal or nearly normal on IKDC

14

Yoldas

2003 19/20 reported normal or nearly normal on IKDC

Wirth15

2002 Recorded substantial improvement in both Lysholm and Tegner scores

16

Rath

2001 Significantly reduced pain and increase function (SF-36)

Cameron17

1997 80% of patients who had ACLR þ MAT had good-excellent results; 86% of those who had ACLR, MAT, and HTO had good to excellent results

ACLR with HTO Williams24

2003 Found statistically significant increases in Lysholm, HSS, Tegner score; 92% of patients were satisfied

25

2000 Pain was reduced in 71% of knees; 71% of patients reported their knees as very good/normal or good

Noyes

Stutz26

1996 8/13 patients had normal or nearly normal subjective IKDC scores 29

Lattermann

1996 3/8 patients had pain even with light activity

Neuschwander27 1993 4/5 patients had good or excellent result; one had fair Noyes25

1993 94% of patients reported significant improvement

ACI, Autologous chondrocyte implantation; ACLR, anterior cruciate ligament reconstruction; HSS, Hospital for Special Surgery; HTO, high-tibial osteotomy; IKDC, International Knee Documentation Committee; MAT, meniscal allograft transplantation; OATS, osteochondral autograft transfer system.

of the surgical procedures. We will discuss the relative risk for each procedure in this regard. Above all, the knee must be flexible and noninflamed before surgery is performed. The reliability of the patient and access to appropriate physical therapy resources must also be factors in decisionmaking.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND MICROFRACTURE Microfracture has been shown to be an effective procedure for generating a fibrocartilaginous fill for full-thickness articular cartilage defects.1–3 It can easily be performed together with ACLR and should be performed simultaneously whenever possible to save the patient an extra and unnecessary anesthetic. The 6-week postoperative period of touchdown weight bearing that is required after 494

microfracture (MF) does not adversely affect the ACLR. It is important only to make sure that good passive range of motion (ROM) is achieved. Decreased activity after ACLR has actually been associated with less tunnel widening in one study.4 For those who believe in aggressive strengthening immediately after ACLR, this regimen will seem restrictive. However, in the long term there should be no adverse effect. We have not found the addition of ACLR to adversely affect the expected good results after microfractures. There is no 2-year follow-up literature on ACLR with microfracture of which we are aware. However, our clinical experience has been favorable with lesions less than 2 cm. We have found larger lesions to not fare as well and in earlier years had to revise several microfractures to autologous chondrocyte implantations (ACI). Although the ultimate results in those cases were good, in recent years we have proceeded directly to ACI when encountering lesions greater than 2 cm.

Anterior Cruciate Ligament Reconstruction Combined with High-Tibial Osteotomy

63

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND AUTOLOGOUS CHONDROCYTE IMPLANTATIONS ACI5–7 is the first procedure that has successfully generated hyaline-like cartilage in full-thickness articular cartilage defects. It is usually not carried out simultaneously with ACLR because the ACLR is usually performed before the need for ACI has been discovered. Thus the articular cartilage biopsy (ACB), rather than the ACI, is usually performed at the time of the ACLR. Generally the ACI will be performed as a staged subsequent procedure. If the lesion is on the femoral condyles, as opposed to the trochlea, we prefer to wait 4 to 6 months before performing ACI after ACLR. The reason is that ACI can involve hyperflexion of the knee to sew to the posterior aspect of many lesions. This hyperflexion will stress the graft, and we prefer not to subject newly implanted grafts to this stress. During the revascularization phase in the first few months postoperatively, grafts are severely weakened and are subject to plastic deformation if stressed. Trochlear grafts are implanted without hyperflexion and thus are safe early after ACLR. Allograft ACL grafts may need to be protected longer. If ACI and ACLR are performed simultaneously, the more restrictive ACI protocol needs to be adopted. This should not adversely affect the ACLR results. In general it is not advisable to perform ACI before ACLR because a stable knee is considered necessary for successful ACI. Also, this type of sequencing would require three procedures because the ACB needs to precede the ACI. However, in cases when the ACB has been performed prior to the ACLR, the ACI and ACLR may then be carried out simultaneously at a subsequent procedure. Good results have been reported after the combined procedures.8 Young patients with acute lesions, such as the 17-year-old girl shown in Fig. 63-1, are ideal candidates. Older patients with acute lesions can also obtain excellent results with ACLR and ACI, such as was the case with a 53-year-old woman who tore her ACL while snow skiing (Fig. 63-2). When the ACL tear is somewhat chronic even in a young patient, such as the 27-year-old woman with a failed ACLR performed at age 20 (Fig. 63-3), early degenerative changes can make treatment more difficult.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND MENISCAL ALLOGRAFT IMPLANTATION Meniscal allograft implantation (MAT) has been associated with generally high success rates.9–11 There is some risk in

FIG. 63-1 This 3.5-cm2 femoral condyle lesion occurred in a 17-year-old girl with a torn anterior cruciate ligament (ACL). She had hamstring ACL reconstruction with simultaneous articular cartilage biopsy, with autologous chondrocyte implantation (ACI) to follow as a staged procedure.

FIG. 63-2 53-year-old woman with acute anterior cruciate ligament (ACL) tear and large medial femoral condyle (MFC) lesion in an otherwise healthy knee.

performing MAT simultaneously with ACLR because there is a propensity in some knees for stiffness after MAT. Crowding also occurs between the tibial tunnel for the ACLR and the trough for lateral MAT as well as the bone tunnel(s) for medial MAT. However, if these are the only two procedures necessary and if the surgeon has sufficient experience with both procedures, then it is possible to perform them simultaneously to save the patient the discomfort of a second procedure. The rehabilitation protocols are compatible, and avoidance of stiffness needs to be prioritized by using appropriately aggressive rehabilitation. If the ACLR is performed first, we prefer to wait 4 to 6 months before performing the 495

Anterior Cruciate Ligament Reconstruction

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND HIGH-TIBIAL OSTEOTOMY

FIG. 63-3 This 27-year-old woman, with a failed anterior cruciate ligament (ACL) reconstruction performed at age 20, already has significant degenerative articular cartilage disease.

MAT to allow the graft to mature as described in the section on ACLR and ACI. In theory, MAT should not performed before ACLR because a stable knee is a prerequisite for the performance of MAT. However, MAT followed within a few months by ACLR should not subject the graft to undue stress because the patient will not be vigorously active during this period. Indeed, if the procedures are staged it may be technically easier to perform the ACLR second because the MAT will be more easily performed in the knee with greater laxity before the ACLR.12–17 The patient whose radiographs are shown in Fig. 63-4 had severe pain and was unable to perform his job as a federal law enforcement agent at 38 years of age, 16 years after ACL tear and meniscectomy. He underwent high-tibial osteotomy (HTO) with substantial improvement. ACLR was then performed with further improvement but with residual medial pain still persisting. MAT was then performed, leading to almost complete resolution of symptoms 1 year after surgery. These procedures allowed him to resume his career, including his 1-mile-run test, without pain.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND OSTEOCHONDRAL ALLOGRAFT OR OSTEOCHONDRAL AUTOGRAFT TRANSFER SYSTEM Osteochondral autograft transfer system (OATS)18 and osteochondral allograft (OCAI)19 are widely used procedures. Either can be performed simultaneously with ACLR if the surgeon has sufficient experience. They can also be performed sequentially before or after ACLR. The literature has shown good results.20,21 496

HTO has shown good results over many decades of use.22,23 Numerous newer reports show good results after combined ACLR and HTO,24–28 although the complication rate can be significant.29 This combination also entails a potentially greater risk of stiffness relative to the other combined procedures. The reason is that all osteotomies, regardless of the surgical technique used, are somewhat unstable in the first few months postoperatively. Thus if the ACLR/HTO surgery does result in significant stiffness, it is harder to treat because aggressive mobilization of the knee cannot be performed in the first few months post-HTO due to the risk of displacing the osteotomy, even if rigid internal fixation is used. This is also somewhat dependent on the HTO technique used. Techniques performed above the tibial tubercle involve the periarticular structures. These HTO procedures add their own propensity to stiffness to that of the ACLR. Procedures performed below the tibial tubercle should involve less such risk. The surgeon must therefore assess the risks attendant to both the ACLR and HTO procedures as best as possible and decide whether there is excessive risk in performing both procedures simultaneously. We perform a bone transport osteotomy below the tubercle using an external fixator and no hardware, which has little risk of stiffness. Our hamstring ACLR procedure has also had excellent ROM results.30 However, some ACLRs have required aggressive rehabilitation to regain full extension. Even though the number is small, it is difficult to predict with which knees this will occur. HTO patients often have some degree of medial arthrosis. These knees are also somewhat predisposed to stiffness. Therefore, where possible, we prefer to perform the ACLR first, establish full ROM, and then perform the HTO on a staged basis as soon as full motion is obtained. If this staged schedule is too difficult for the patient, the HTO can be performed simultaneously with a full discussion of potential stiffness risk. Although the senior author has not had a permanent motion problem with the combined procedures, he nonetheless considers the staged procedure to be safer in these complicated knees. We have found HTO to be an extremely reliable procedure for unicompartmental varus and have found the results of the combined procedure (simultaneously or staged) to be excellent. Initially we worried that ACLR in the presence of medial arthrosis might aggravate the arthrosis. However, we have never seen this occur and instead have found the ACLR to consistently result in clinical improvement in the symptoms of even moderate arthritis.

Anterior Cruciate Ligament Reconstruction Combined with High-Tibial Osteotomy

63

FIG. 63-4 A and B, This 38-year-old federal law enforcement agent had chronic pain and was limited to primarily sedentary work after anterior cruciate ligament (ACL) tear and medial meniscectomy 16 years earlier. He had high-tibial osteotomy (HTO) and ACL reconstruction with marked improvement but still had limiting medial pain. He then underwent meniscal allograft implantation (MAT). One year later, he was pain free and able to perform his 1-mile run without pain.

497

Anterior Cruciate Ligament Reconstruction We will perform ACLR/HTO in the presence of a moderate diminution in the medial joint space in a young patient. We will not, however, perform ACLR with HTO if bony deformity, subluxation, or severe loss of joint space is present. If all else is equal, greater aggressiveness is more justified in younger patients to avoid progression to joint replacement arthroplasty. HTO is performed far less often in the United States than in Europe, apparently due to reasons of patient acceptance. However, with proper discussion patients are usually quite willing to undergo HTO. With the external fixator technique, patient acceptance is increased by the fact that alignment is precisely controlled on an outpatient basis, precluding excessive unattractive valgus. The use of only a small incision without retained hardware is also appealing. The presence of protruding pins is distasteful to some patients, but this is mitigated by the fact that the pins are only temporary. Other methods have their own advantages and disadvantages.

We perform HTO when mechanical axis radiographs (on standing hip-knee-ankle films) show four degrees or more of varus. It is important to point out that medial compartment cartilage restoration procedures generally have been shown to have a higher failure rate if HTO is not performed in the presence of significant varus. Thus although HTO is a procedure that many orthopaedic surgeons may not feel comfortable performing, it is important to perform where indicated. HTO procedures are not without complications, and these patients must be operated on carefully and followed closely. Most, however, have a smooth course. Fig. 63-5 shows a patient 8 months after simultaneous ACLR and HTO. The osteotomy is well healed. The tibial fixation screw for the ACL graft can be seen proximal to the osteotomy. The medial joint space on these standing views shows increased cartilage space in the postoperative radiograph compared with preoperatively.

FIG. 63-5 Anterior cruciate ligament reconstruction with high-tibial osteotomy (ACLR/HTO). A, Preoperative view. B, Postoperative view.

498

Anterior Cruciate Ligament Reconstruction Combined with High-Tibial Osteotomy

MULTIPLE CARTILAGE RESTORATIVE PROCEDURES Some patients require multiple procedures in addition to ACLR. The surgeon should separately consider the following five components of knee health: (1) articular cartilage, (2) menisci, (3) limb alignment, (4) bone deficiency, and (5) ACL deficiency. Thus a patient may need, for example, HTO for varus, MAT for symptomatic meniscal deficiency, ACI or MF for articular cartilage deficiency, and possibly a bone graft for osteochondritis desiccans. Staging becomes even more complicated in these cases. In general it is advisable to avoid combining more than two major procedures at once to avoid the risks of stiffness and infection. We have not had a deep infection in these combined cases, and an increased infection rate is not reflected in the literature.

CARTILAGE PRESERVATION VERSUS ARTHROPLASTY Cartilage preservation is perhaps the most important reason to perform ACLR. In those cases in which articular cartilage damage has also occurred and the patient is symptomatic, restorative procedures may be necessary. If the surgeon performing the ACLR is not comfortable with these procedures, the patient may be referred to a surgeon either initially or after ACL reconstruction is completed. The references cited in this chapter indicate that success rates are high. Treatment of their pathology would seem to be preferable to advising patients that they should wait for further degeneration and have a joint replacement arthroplasty, as patients young enough to be ACLR candidates are generally too young to be good candidates for joint replacement. We wish to emphasize that, with some exceptions, only symptomatic patients should be treated. Asymptomatic varus is generally not a reason to perform HTO, nor is asymptomatic meniscal deficiency a reason to perform MAT. The exception to this rule may be articular cartilage deficiency in a younger patient. Even asymptomatic, full-thickness lesions in this population probably warrant treatment to prevent propagation. The sooner the patient’s cartilage deficiencies are treated, the better his or her outcome is likely to be.

CONCLUSIONS 1 HTO, MF, ACI, MAT, OATS, and OCAI have demonstrated good results in the literature in conjunction with ACLR. Whether to perform them simultaneously or sequentially is dependent on the characteristics of each case.

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2 Restoration of satisfactory motion is of primary importance. 3 Correction of significant varus with HTO is advisable so that other medial cartilage restoration procedures will enjoy an optimal success rate. 4 Patients young enough to be ACLR candidates are generally too young to be good candidates for joint replacement arthroplasty, and correction of their pathology is preferable. 5 These cases are complicated and require extra time and care.

References 1. Gill TJ. The role of the microfracture technique in the treatment of full-thickness chondral injuries. Oper Tech Sports Med 2000;8:138–140. 2. Gobbi A, Nunag P, Malinowski K. Treatment of full thickness chondral lesions of the knee with microfracture in a group of athletes. Knee Surg Sports Traumatol Arthrosc 2005;13:213–221. 3. Miller BS, Steadman JR, Briggs KK, et al. Patient satisfaction and outcome after microfracture of the degenerative knee. J Knee Surg 2004;17:13–17. 4. Hantes ME, Mastrokalos DS, Yu J, et al. The effect of early motion on tibial tunnel widening after anterior cruciate ligament replacement using hamstring tendon grafts. Arthroscopy 2004;20:572–580. 5. Bentley G, Biant LC, Carrington WJ, et al. A prospective, randomised comparison of autologous chondrocyte implantation versus mosaicplasty for osteochondral defects in the knee. J Bone Joint Surg 2003;85:223–230. 6. Minas T, Chiu R. Autologous chondrocyte implantation. Am J Knee Surg 2000;13:41–50. 7. Peterson L, Minas T, Brittberg M, et al. Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop Relat Res 2000;374:212–234. 8. Amin AA, Bartlett W, Gooding CR, et al. The use of autologous chondrocyte implantation following and combined with anterior cruciate ligament reconstruction. Int Orthop 2006;30:48–53. 9. Fukushima K, Adachi N, Lee JY, Moore GG. Meniscus allograft transplantation using posterior peripheral suture technique: a preliminary follow-up study. J Orthop Sci 2004;9:235–241. 10. Ryu RKN, Dunbar WH, et al. Meniscal allograft replacement: a 1-year to 6-year experience. Arthroscopy 2002;18:989–994. 11. Sekiya JK, Giffin JR, Irrgang JJ, et al. Clinical outcomes after combined meniscal allograft transplantation and anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:896–906. 12. Graf KW Jr, Sekiya JK, Wojtys EM. Long-term results after combined medial meniscal allograft transplantation and anterior cruciate ligament reconstruction: minimum 8.5-year follow-up study. Arthroscopy 2004;20:129–140. 13. Sekiya JK, Giffin JR, Irrgang JJ, et al. Clinical outcomes after combined meniscal allograft transplantation and anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:896–906. 14. Yoldas EA, Sekiya JK, Irrgang JJ, et al. Arthroscopically assisted meniscal allograft transplantation with and without combined anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2003;11:173–182. 15. Wirth CJ, Peters G, Milachowski KA, et al. Long-term results of meniscal allograft transplantation. Am J Sports Med 2002;30:174–181. 16. Rath E, Richmond JC, Yassir W, et al. Meniscal allograft transplantation. Two- to eight-year results. Am J Sports Med 2001;29:410–414.

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Anterior Cruciate Ligament Reconstruction 17. Cameron JC, Saha S. Meniscal allograft transplantation for unicompartmental arthritis of the knee. Clin Orthop Relat Res 1997;337:164–171. 18. Gudas R, Stankevicius E, Monastyreckiene E, et al. Osteochondral autologous transplantation versus microfracture for the treatment of articular cartilage defects in the knee joint in athletes. Knee Surg Sports Traumatol Arthrosc 2006;14:834–842. 19. Aubin PP, Cheak HK, Davis AM, et al. Long-term followup of fresh femoral osteochondral allografts for posttraumatic knee defects. Clin Orthop Relat Res 2001;391S:S318–S327. 20. Klinger HM, Baums MH, Otte S, et al. Anterior cruciate reconstruction combined with autologous osteochondral transplantation. Knee Surg Sports Traumatol Arthrosc 2003;11:366–371. 21. Bobic V. Arthroscopic osteochondral autograft transplantation in anterior cruciate ligament reconstruction: a preliminary clinical study. Knee Surg Sports Traumatol Arthrosc 1996;3:262–264. 22. Koshino T, Wada S, Ara Y, Saito T. Regeneration of degenerated articular cartilage after high tibial valgus osteotomy for medial compartmental osteoarthritis of the knee. Knee 2003;10:229–236. 23. Sprenger TR, Doerzbacher JF. Tibial osteotomy for the treatment of varus gonarthrosis. J Bone Joint Surg 2003;85A:469–474.

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24. Williams RJ III, Kelly BT, Wickiewicz TL, et al. The short-term outcome of surgical treatment for painful varus arthritis in association with chronic ACL deficiency. J Knee Surg 2003;16:9–16. 25. Noyes FR, Barber-Westin SD, Hewett TE. High tibial osteotomy and ligament reconstruction for varus angulated anterior cruciate ligament-deficient knees. Am J Sports Med 2000;28:282–296. 26. Stutz G, Boss A, Gachter A. Comparison of augmented and nonaugmented anterior cruciate ligament reconstruction combined with high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 1996;4:143–148. 27. Neuschwander DC, Drez D Jr, Paine RM. Simultaneous high tibial osteotomy and ACL reconstruction for combined genu varum and symptomatic ACL tear. Orthopedics 1993;16:679–684. 28. Noyes FR, Barber SD, Simon R. High tibial osteotomy and ligament reconstruction in varus angulated, anterior cruciate ligament-deficient knees. A two- to seven-year follow-up study. Am J Sports Med 1993;21:2–12. 29. Lattermann C, Jakob RP. High tibial osteotomy alone or combined with ligament reconstruction in anterior cruciate ligament-deficient knees. Knee Surg Sports Traumatol Arthrosc 1996;4:32–38. 30. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146.

PART O REHABILITATION

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises This chapter describes the devices, methods, and approaches used to measure anterior cruciate ligament (ACL) strain in vivo and provides insight into the strain behavior of the normal ACL during various rehabilitation activities. The effectiveness of functional knee bracing on the ACL and the strain behavior of the bone– patellar tendon–bone (BPTB) graft after the reconstruction of the ACL are also reviewed.

DESCRIPTION OF THE DEVICES, METHODS, AND APPROACHES USED TO MEASURE ANTERIOR CRUCIATE LIGAMENT BIOMECHANICS IN VIVO Henning et al1 were the first researchers to measure the elongation behavior of the ACL in vivo. A hooked pin was attached to the partially disrupted ACL in two patients, and the peak displacement of the pin was measured during different rehabilitation activities. Absolute strain values were not reported. The displacement measurements for various activities were compared with that produced by a 350N, anteriorly directed shear load applied to the tibia during the Lachman test. Although this method has several obvious limitations, it was one of the first studies that measured the ACL in vivo. Subsequent to this work, ACL strain measurements have been performed in vivo using both the Hall Effect Strain Transducer (HEST, MicroStrain, Williston, VT) and the Differential Variable Reluctance Transducer (DVRT,

MicroStrain, Williston, VT) (Fig. 64-1). Both displacement transducers are small (4–5 mm in length), are highly compliant, have a similar barbed attachment technique, can be sterilized, and can be implanted arthroscopically to the anteromedial aspect of the ACL in vivo.2,3 Although the devices have many similarities, the sensing technology is different, and the DVRT is now more frequently used than the HEST, mainly due to its improved accuracy, better precision, and lower profile.3 The HEST is composed of an inner tube that slides with an outer tube. At the end of each tube are barbs that attach the sensor to the ligament. The inner tube houses a magnet, and the outer tube has a Hall effect magnetic sensor. As the length of the ligament changes, the magnet moves relative to the Hall effect sensor, and this produces the relative change in length between the two barbs. In comparison, the DVRT detects the movement of the two barbs attached to the ligament by measuring the differential change in reluctance produced by the position change of a magnetically permeable core within two small coil windings that are excited with an alternating current (AC) signal.2 The DVRT is currently the displacement transducer of choice.2,3 The monotonic sensing range of a 5-mm DVRT is 1.75 mm, creating a linear sensing range of 35%. The displacement sensitivity is typically 2 V/mm, and the signal: noise ratio is 1000:1. The DVRT has 3.5 mm of nonlinearity, 1 mm of hysteresis, 1 mm nonrepeatability, 0.1 mm/ C temperature error coefficient, and 7 mm root mean square (RMS) error

64 CHAPTER

Petteri Kousa James R. Slauterbeck Bruce D. Beynnon

501

Anterior Cruciate Ligament Reconstruction

Posterior cruciate ligament Anterior cruciate ligament DVRT

Removal sutures

To data acquisition

FIG. 64-1 A schematic drawing showing the differential variable reluctance transducer (DVRT) applied to the anteromedial portion of the anterior cruciate ligament (ACL).

(or 0.1% strain). The DVRT is calibrated with a specially designed micrometer system (AutoCal, MicroStrain, Burlington, VT).2,3 The displacement transducer is implanted into the knee joint through a lateral parapatellar arthroscopic portal (incision) of the joint capsule with the knee at approximately 90 degrees of flexion. The sensing axis of the device is aligned with the anteromedial fibers of the ACL. The two fixation barbs of the device are then pressed into the ligament. Repeated anteroposterior shear loading tests (Lachman) are performed at the beginning and end of a protocol to determine the reference for strain calculation and to serve as a “repeated normal” test to ensure that the transducer measurements are reproducible.2,3 For calculations of ACL strain, it is important to determine a reference length (the length of the transducer when the ACL becomes taut in response to palpation).4 When a posteriorly directed shear load is applied to the tibia with the knee at 30 degrees of flexion, the ACL becomes unstrained and is unloaded in response to palpation. When an anteriorly directed shear load is applied to the tibia, the ACL becomes taut.2–4 This slack–taut transition is identified from the applied anteroposterior loading versus DVRT output plot as the inflection point.4 For the anteromedial 502

portion of the ACL, this slack–taut transition point can estimate the absolute reference within 0.7% strain.4 The wire connections for data acquisition and transducer removal are allowed to course through the lateral portal, and the function of the sensor through the desired range of motion is checked prior to closing the arthroscopic portals and applying sterile dressing such as Tegaderm.3 The DVRT has many advantageous characteristics for measuring ACL strain in vivo. It is relatively small (approximately 5 mm), is lightweight, and can be attached to the ACL arthroscopically. Ligaments have a strain distribution about their length and cross-section, and the DVRT allows accurate, reliable, and repeatable strain measurements of specific regions of a ligament. In addition, the calibration remains stable in environments that range between room temperature and body temperature, making it very practical. Over the years, the DVRT has been shown to be biotolerable and safe, without any adverse long-term reactions.2,3 The limitations of the DVRT must be appreciated. First, although the DVRT is small, the anatomy of the femoral intercondylar notch, combined with the constraints produced by the arthroscopic portals, constrains placement of the sensor to the anteromedial portion of the ACL in humans.2,3 Although the current ACL reconstruction techniques aim to reproduce the function of the anteromedial bundle, recent reports suggest that it may be important to replicate the function of both bundles of the ACL to better restore rotational and anteroposterior limits of motion of the knee.5,6 Second, impingement of the device against the roof of the femoral intercondylar notch does not allow measurement of ACL strain when the knee is in extension or hyperextension. Therefore it is difficult to study activities such as gait and landing from a jump. An in vitro technique measuring both strain and resultant force in the entire ACL was developed by Markolf et al7 and is useful in interpreting the DVRT data. The technique involves mechanically isolating the bone insertion of the ACL and attaching a load cell to the bone–ligament complex. Throughout the procedure the anatomical origin and insertion are maintained in space.7 Loads and torques can be applied to the knee, and forces, stresses, and strains can be directly measured.8–12 Markolf et al13,14 tested the DVRT and the ACL mechanical isolation technique in the same experiment, creating calibration curves to estimate resultant forces in the ACL from strain measurements made in vivo. In so doing, all the data from the prior DVRT measurements can be related to resultant force measurements for common activities when the forces and moments produced across the knee in vivo are replicated in vitro.2,3,15–17 Recently, noninvasive imaging techniques have been introduced for measuring the in vivo kinematics of the tibia relative to the femur, and these data have been used to

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises estimate ACL biomechanics.5,18,19 Sheehan and Rebmann19 used a cine–phase contrast magnetic resonance imaging (MRI) technique to evaluate the orientation of the attachment sites of the ACL during non–weight-bearing flexion, whereas Li et al5,18 used a combined imaging and threedimensional (3D) computer-modeling technique to evaluate the orientation of the attachment sites of the ACL during weight-bearing flexion of the knee (one-legged lunge). Although these new, MRI-based, noninvasive techniques have apparent limitations, they have opened a new era for measuring the in vivo kinematics of the knee. For the cine–phase contrast MRI technique, the cine MRI produced the anatomical images during periodic motion, and phase contrast MRI measured the 3D velocities in the imaging plane.19 The ACL strain was calculated by combining the velocity and anatomical data obtained from the cine–phase contrast MR images. The insertions of the ACL were identified, and the lengths of the anterior and posterior regions of the ACL were calculated for a selection of different knee flexion angles. When compared with DVRT measurements, the cine–phase contrast MRI method revealed a similar strain pattern of the anterior region of the ACL during active extension of the knee. However, for the cine–phase contrast MRI method, the strain values were more than three times greater, approaching the failure strains of the ACL, and thus this approach may overestimate the ACL strain values.19 For the technique that combined imaging and 3D computer modeling, MR images were first taken of human subjects to construct a 3D model for each knee.5,18 After modeling, each subject performed a lunge, and two orthogonal fluoroscopic images were taken at four selected flexion angles to re-create the in vivo knee positions. These orthogonal images and the 3D knee model were then manually matched to reproduce the kinematics of the knee. The tibial and femoral insertion sites were identified to investigate the ACL attachment site’s biomechanics. The position of knee at full extension was used as reference. During the onelegged lunge, Li et al18 demonstrated that the anteromedial bundle of the ACL decreased in length by 7% when the knee moved from extension to flexion. These results are in agreement with those measured with the DVRT.

REVIEW OF STUDIES THAT HAVE CHARACTERIZED ANTERIOR CRUCIATE LIGAMENT STRAIN BEHAVIOR DURING REHABILITATION EXERCISES In vivo ACL strain measurements of patient volunteers with normal ACLs have been carried out to describe the strain

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behavior of the ACL during commonly prescribed rehabilitation exercises and have been used to establish clinical criteria for ACL reconstruction. These studies also serve as a basis for development of rehabilitation programs that do not jeopardize the survival of the ACL graft but still allow exercises for optimal recovery of muscle strength and range of motion following ACL reconstruction. Rank comparison of peak ACL strain values produced during common rehabilitation activities are summarized in Table 64-1. Most of the strain transducer measurements have been performed under local (intraarticular) anesthesia, allowing the patients to have full control of their muscles. Typically the study participants have been candidates for arthroscopic partial meniscectomy or diagnostic arthroscopy without known ligament trauma. Preoperatively the patients have had normal gait, range of motion, and normal ligament function as documented by clinical examination and arthroscopic visualization.2,3 The ACL strain measurements have revealed that during passive flexion–extension motion of the lower leg with the thigh held in a horizontal position, the ACL is unstrained between 110 and 11.5 degrees of flexion and becomes strained as the knee is moved into terminal extension.20 Although the impingement of the strain transducer against the roof of the femoral intercondylar notch has not allowed measurements of the ACL strain during hyperextension of the knee in all patients, these findings indicate that the ACL strain continues to increase with increasing extension of the knee and is greatest when the knee is in hyperextension. To support this, in vitro studies have demonstrated that ACL strain and force increase as the knee is passively moved from a flexed position to an extended (0 degrees) position and then to a hyperextended position.9–11,21,22 The following general conclusions can be made regarding the effect of externally applied loads on ACL strain values: The ACL is a primary restraint to anterior displacement of the tibia relative to the femur when the knee is near extension, and it also restrains internal (but not external) axial rotation of the tibia.2,3,17 Although cadaver studies have revealed that the ACL serves as an important secondary restraint to applied varus-valgus moments, in vivo measurements have revealed that ACL strain values are not increased when varus and valgus moments are applied to the knee at 20 degrees of flexion.3,17 In addition, in vivo measurements have shown different ACL strain values during non–weight-bearing versus weight-bearing conditions. For example, transitioning from non–weight-bearing to weight-bearing conditions increases ACL strain values when varus-valgus moments and external torque are applied to the knee.17 In addition, when anteriorly directed shear loads are applied to the tibia, the strain values are higher 503

Anterior Cruciate Ligament Reconstruction TABLE 64-1 Rank Comparison of Average Peak Anterior Cruciate Ligament Strain Values Measured During Various Rehabilitation Activities Rehabilitation Activity

Resistance

Peak Strain

Isometric quadriceps contraction at 15 degrees

30 Nm of extension torque

4.4%

Squatting

Sport Cord

4.0%

Active flexion–extension

45N weight boot

3.8%

Lachman test

150N anterior shear load

3.7%

Squatting

3.6%

Gastrocnemius contraction at 15 degrees of knee flexion

15 Nm of ankle torque

3.5%

Active extension of the knee

12 Nm of extension torque

3.0%

One-legged sit to stand Active extension

2.8% Leg weight only

Combined isometric quadriceps and hamstring contraction at 15 degrees Gastrocnemius contraction at 5 degrees of knee flexion

2.8% 15 Nm of ankle torque

Stair climbing Isometric quadriceps contraction at 30 degrees

2.8% 2.7%

30 Nm of extension torque

2.7%

Step-down (during extension phase of the exercise cycle)

2.6%

Step-up

2.5%

Lunge (during extension phase of the exercise cycle)

2.0%

Anterior drawer

150N anterior shear load

Stationary bicycling

1.8% 1.7%

Active flexion of the knee

12 Nm of flexion torque

1.5%

Isometric hamstring contraction at 15 degrees

10 Nm of flexion torque

0.6%

Combined isometric quadriceps and hamstring contraction at 30 degrees

0.4%

Passive flexion–extension

0.1%

Gastrocnemius contraction at 30 and 45 degrees of knee flexion

15 Nm of ankle torque

0%

Isometric quadriceps contraction at 60 degrees

30 Nm of extension torque

0%

Isometric quadriceps contraction at 90 degrees

30 Nm of extension torque

0%

Combined isometric quadriceps and hamstring contraction at 60 degrees

0%

Combined isometric quadriceps and hamstring contraction at 90 degrees

0%

Isometric hamstring contraction at 30, 60, and 90 degrees

0%

during weight-bearing conditions in comparison with non– weight-bearing conditions.17 When compared with the fully relaxed condition, extension torque produced by isometric quadriceps muscle contraction has been shown to strain the ACL near extension of the knee, but not beyond 60 degrees of flexion.15 Isometric hamstring contraction, on the other hand, has not been shown to produce ACL strain at any knee flexion 504

2.8%

angles.15 When compared with the relaxed condition, combined contraction of quadriceps and hamstring muscles has been shown to produce a significant increase in strain at 15 degrees of knee flexion, but not at 30, 60, or 90 degrees of knee flexion.15 Isometric gastrocnemius muscle contraction has been shown to strain the ACL when the knee is near extension (at 5 and 15 degrees of flexion), and when gastrocnemius muscle contraction was combined with

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises quadriceps or hamstring muscle contraction, the strain was increased in comparison with isolated contractions of these muscles.23 It has been common practice to consider rehabilitation programs as comprising open and closed kinetic chain exercises. Closed kinetic chain exercises, such as squats, are performed with the foot fixed against resistance, whereas during an open kinetic chain exercise, such as knee extension, the foot is not constrained by a platform and is unloaded. Compressive loading of the tibiofemoral joint produced during closed kinetic chain exercise has been thought to protect the injured ACL or healing ACL graft because of the increased joint stiffness and decreased anterior displacement of the tibia relative to the femur. In addition, co-contraction of the hamstring muscles during closed kinetic chain exercises has been considered to protect the injured knee from excessive ACL strains. Active extension–flexion motion of the knee (an open kinetic chain exercise) between the limits of 10 and 90 degrees produces peak ACL strains near extension, and these values gradually decrease with increasing knee flexion.15 Beyond 35 degrees of knee flexion, the ACL becomes unstrained.15 Application of weight during this exercise (applied to increase extension torque about the knee) produces significant increases of ACL strain values at 10 and 20 degrees of flexion and shifts the strained–unstrained transition to 45 degrees of knee flexion. A subsequent follow-up study confirmed that the peak ACL strain values increased when knee extension torque increased.16 It was also shown that application of compressive loading, such as that produced by body weight, did not reduce peak ACL strains during extension exercises.16 Application of flexion torque during flexor exercise produced significant decreases of ACL strain values; however, when compressive loading was added, such a decrease was not observed.16 Stair climbing is a closed kinetic chain exercise, and because step-up exercise has been shown to reduce anterior translation of the tibia with respect to the femur, it is commonly considered safe for rehabilitation following ACL reconstruction.24 In vivo measurements during stationary stair-climbing exercises have demonstrated that ACL strain is increased when the knee moves from a flexed to an extended position, and the average strain values were moderate when compared with other commonly prescribed rehabilitation activities tested with the same technique.25 However, the strain values were highly variable, with peak values ranging as much as 7%. These strain magnitudes may produce detrimental effects to the healing graft, and therefore caution should be exercised when making any recommendations for stationary stair climbing following ACL reconstruction. Most clinicians have considered bicycling to be a relatively safe rehabilitation exercise with many therapeutic

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qualities, and therefore it is commonly recommended for rehabilitation following ACL injury or reconstruction. In vivo ACL strain measurements during stationary bicycling also support this observation.26 In an in vivo study, stationary biking was performed at six different riding conditions (three power levels and two cadences).26 Power levels 75 Watts (W), 125W, and 175W simulated downhill, level, and uphill riding conditions, respectively. The results revealed that with this selection of power and cadence levels, stationary bicycling produces relatively low peak strain values (mean 1.7%) when compared with other rehabilitation activities commonly prescribed after ACL injury or reconstruction, and thus stationary bicycling can be considered safe for rehabilitation after ACL reconstruction without excessively straining the graft. However, the safety and efficacy of bicycling, or of any rehabilitation exercise for that matter, following ACL reconstruction can only be determined via clinical studies. Closed kinetic chain squatting exercises are commonly prescribed to improve muscle strength after ACL reconstruction. Because of the compressive joint load and co-contraction of muscles spanning the knee, advocates of closed kinetic chain exercise consider it safer than active flexion–extension exercises. It has been demonstrated that squatting and active flexion–extension exercises produce similar strain patterns (strain is greatest near full extension and gradually decreases toward flexion) and maximum strain values, indicating that compressive joint force does not necessarily protect a healing ACL graft.27 It has to be emphasized, however, that in contrast to active extension of the knee, the increasing resistance during squatting to the limit of 134N did not significantly increase ACL strain values.27 Recently Heijne et al28 measured the strain behavior of the ACL during four different closed kinetic chain exercises: (1) step-up, (2) step-down, (3) lunge, and (4) one-legged sit to stand. They found that the strain produced during these four exercises was not significantly different at all knee positions (knee flexion angles of 30, 50, and 70). The largest strain values were measured when the knee was near extension (at 30 degrees of knee flexion), and the strain values decreased significantly as the knee was flexed. The importance of rehabilitation following ACL reconstruction is greatly appreciated; however, there is little consensus regarding how different restrictions and exercises should be administered and how they influence the long-term outcome and healing response of the graft and knee. The previously mentioned studies characterizing the behavior of the ACL during different activities have been used to design accelerated and nonaccelerated rehabilitation programs that gradually increase the strain experienced in the graft. The accelerated program (19 weeks) produces high graft strain early after the reconstruction by allowing immediate full range of motion, weight bearing as tolerated, quadriceps 505

Anterior Cruciate Ligament Reconstruction activity with the knee near extension, and return to unrestricted activity within 6 months of reconstruction, whereas in the nonaccelerated program (32 weeks) these same activities are prescribed over a delayed time interval and the graft is therefore not strained as vigorously. The effects of these programs have been subsequently studied via a prospective, randomized, double-blinded clinical trial.29 At 2-year follow-up, both rehabilitation programs produced the same increase of anterior knee laxity and the same effect with regard to clinical assessment, patient satisfaction, functional performance, and the biomarkers of articular cartilage metabolism.29

REVIEW OF STUDIES THAT HAVE MEASURED THE STRAIN OF THE BONE–PATELLAR TENDON– BONE GRAFT Proper graft placement directly affects knee biomechanics and has been considered one of the most critical surgical variables in determining a successful long-term clinical outcome. In an attempt to place the graft optimally during ACL reconstruction, “isometers” were introduced to help with placement of ACL graft tunnels. In vivo strain measurements of the BPTB graft at the time of reconstruction have, however, shown that local graft elongation did not correlate with the isometric measurements of displacement made prior to preparing the graft tunnels.30 Consequently, isometers are not currently in routine use in ACL reconstructions. Immediately following fixation of a BPTB graft, cyclical passive extension of the knee between the limits of full extension and 90 degrees of flexion produces a complex seating response of the graft. Unlike the normal ACL, the graft demonstrated a seating behavior by decreasing in length in some patients but increasing in others. Early slippage of the graft bone blocks past the interference screw explains the decrease in length, whereas a creep response of the improperly positioned or overtensioned graft explains the increase in length. Both of these phenomena were found to be associated with increased anteroposterior displacement of the knee during healing.31 The relationship between BPTB graft elongation behavior at the time of surgery and the changes in anteroposterior knee laxity at long-term follow-up have also been evaluated.32 Subjects from the previously mentioned study31 were divided into two groups based on elongation biomechanics of the graft measured after graft fixation. Although both groups had similar anteroposterior knee laxity values at the time of ACL reconstruction, those patients with graft elongation values that were significantly greater than the normal ACL at the time of surgery (outside the 95% confidence interval of the normal ACL) demonstrated a significant 506

increase in anteroposterior knee laxity at the 5-year followup, whereas those with elongation values similar to the normal ACL (within the 95% confidence interval of the normal ACL) did not.32 These results suggest that (1) the elongation behavior of the BPTB graft during flexion– extension cycles at the time of surgery may provide important information for long-term success of the knee and (2) anteroposterior laxity measurements at the time of surgery may not adequately predict changes of anteroposterior laxity of the knee during healing and long-term follow-up.

REVIEW OF STUDIES INVESTIGATING HOW FUNCTIONAL KNEE BRACING AFFECTS ANTERIOR CRUCIATE LIGAMENT STRAIN BEHAVIOR Functional knee braces are designed to protect an injured ACL or ACL graft and to prevent further intraarticular damage by reducing anterior translation of the tibia with respect to the femur. Although these braces are commonly prescribed, their effectiveness is controversial and not well documented on human subjects. Several investigations of functional knee braces have been performed using arthrometers or roentgen stereophotogrammetric analysis to measure the displacement of the tibia relative to the femur.33–35 Common limitations of these studies are that the combined effects of compressive load and muscle loading during weight-bearing activities were not included. In vivo strain measurements of the normal ACL have also been performed during various loading conditions to evaluate the efficacy of functional knee braces.36–38 The results reveal that when the subject is non–weight bearing and weight bearing, bracing the knee reduces ACL strains produced in response to anteriorly directed shear loads.36–38 Additionally, in response to applied internal–external torques with the knee non–weight bearing, the ACL of the braced knee was significantly less strained when 2 to 8 N/m of internal torque was applied compared with the unbraced knee.38 At 9 N/m of internal torque, the difference was not statistically significant; however, there was a strong trend that bracing the non–weight-bearing knee reduces ACL strain values.38 In contrast, when the subject was weight bearing, the brace was no longer able to reduce the strain produced during application of internal torque about the tibia.38

SUMMARY The effect of externally applied loads on ACL strain values is as follows: 1 When the knee is non–weight bearing, anteriorly directed shear load and internal axial torque applied to the tibia strain the ACL.

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises 2 When the knee is non–weight bearing, application of varus–valgus torques and external axial torque to the tibia does not strain the ACL. 3 Transition of the knee from non–weight bearing to weight bearing increases ACL strain values. The strain behavior of the ACL during rehabilitation exercises is as follows: 1 Rehabilitation exercises that produce the greatest ACL strain values are produced by contraction of the quadriceps muscles with the knee between 60 degrees of flexion and full extension (i.e., isometric quadriceps contraction, squatting, active extension of the knee, stair climbing, step-up, and step-down). 2 In contrast to common belief, the compressive knee joint load, produced by body weight, strains the ACL during rehabilitation exercises. Adding resistance during closed kinetic chain exercises such as squatting is not associated with a proportional increase in ACL strain values; in contrast, adding resistance during an open kinetic chain active extension exercise increases ACL strain values. 3 Low- or unstrained-ACL values have been observed in response to (1) contraction of the hamstring muscle group (isometric hamstring muscle contraction and active contraction of the flexors at all flexion angles), (2) isometric contraction of quadriceps muscle beyond 60 degrees of knee flexion, (3) co-contraction of quadriceps and hamstring muscle groups with the knee flexed at 30 degrees or greater, and (4) active knee flexion–extension motion without resistance between 35 and 90 degrees.

References 1. Henning CE, Lynch MA, Glick KR. An in vivo strain gauge study of elongation of the anterior cruciate ligament. Am J Sports Med 1985;13:22–26. 2. Beynnon BD, Fleming BC. Anterior cruciate ligament strain in-vivo: a review of previous work. J Biomech 1998;31:519–525. 3. Fleming BC, Beynnon BD. In vivo measurement of ligament/tendon strains and forces: a review. Ann Biomed Eng 2004;32:318–328. 4. Fleming BC, Beynnon BD, Tohyama H, et al. Determination of a zero strain reference for the anteromedial band of the anterior cruciate ligament. J Orthop Res 1994a;12:789–795. 5. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 6. Woo SL-Y, Kanamori A, Zeminski J, et al. The effectiveness of reconstruction of the anterior cruciate ligament with hamstring and patellar tendon. A cadaveric study comparing anterior tibial and rotational loads. J Bone Joint Surg 2002;84A:907–914. 7. Markolf KL, Gorek JF, Kabo JM, et al. Direct measurement of resultant forces in the anterior cruciate ligament. An in vitro study performed with a new experimental technique. J Bone Joint Surg 1990;72A:557–567.

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8. Markolf KL, Burchfield DM, Shapiro MM, et al. Combined knee loading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13:930–935. 9. Markolf KL, Burchfield DM, Shapiro MM, et al. Biomechanical consequences of replacement of the anterior cruciate ligament with patellar ligament allograft. Part I: insertion of the graft and anteriorposterior testing. J Bone Joint Surg 1996;78A:1720–1727. 10. Markolf KL, Burchfield DM, Shapiro MM, et al. Biomechanical consequences of replacement of the anterior cruciate ligament with patellar ligament allograft. Part II: forces in the graft compared with forces in the intact ligament. J Bone Joint Surg 1996;78A:1728–1734. 11. Markolf KL, Wascher DC, Finerman GA. Direct in vitro measurement of forces in the cruciate ligaments. Part I: the effect of multiplane loading in the intact knee. J Bone Joint Surg 1993;75A:377–386. 12. Markolf KL, Wascher DC, Finerman GA. Direct in vitro measurement of forces in the cruciate ligaments. Part II: the effect of section of the posterolateral structures. J Bone Joint Surg 1993;75A:387–394. 13. Markolf KL, Willems MJ, Jackson SR, et al. In situ calibration of miniature sensors implanted into the anterior cruciate ligament part I: strain measurements. J Orthop Res 1998;16:455–463. 14. Markolf KL, Willems MJ, Jackson SR, et al. In situ calibration of miniature sensors implanted into the anterior cruciate ligament part II: force probe measurements. J Orthop Res 1998;16:464–471. 15. Beynnon BD, Fleming BC, Johnson RJ, et al. Anterior cruciate ligament strain behavior during rehabilitation exercises in vivo. Am J Sports Med 1995;23:24–34. 16. Fleming BC, Ohlén G, Renström PA, et al. The effects of compressive load and knee joint torque on peak anterior cruciate ligament strains. Am J Sports Med 2003;31:701–707. 17. Fleming BC, Renstrom PA, Beynnon BD, et al. The effect of weightbearing and external loading on anterior cruciate ligament strain. J Biomech 2001a;34:163–170. 18. Li G, DeFrate LE, Sun H, et al. In vivo elongation of the anterior cruciate ligament during knee flexion. Am J Sports Med 2004;32:1415–1420. 19. Sheehan FT, Rebmann A. Non-invasive, in vivo measures of anterior cruciate ligament strains. Trans Orthop Res Soc 2003;28:264. 20. Beynnon BD, Howe JG, Pope MH, et al. The measurement of anterior cruciate ligament strain in vivo. Int Orthop 1992;16:1–12. 21. Arms SW, Pope MH, Johnson RJ, et al. The biomechanics of anterior cruciate ligament rehabilitation and reconstruction. Am J Sports Med 1984;12:8–18. 22. Markolf KL, O’Neill G, Jackson SR. Effect of applied quadriceps and hamstring muscle loads on forces in the anterior and posterior cruciate ligaments. Am J Sports Med 2004;32:1144–1149. 23. Fleming BC, Renström PA, Ohlén G, et al. The gastrocnemius muscle is an antagonist of the anterior cruciate ligament. J Orthop Res 2001b;19:1178–1184. 24. Jonsson H, Karrholm J. Three-dimensional knee joint movements during a step-up: evaluation after anterior cruciate ligament rupture. J Orthop Res 1994;12:769–779. 25. Fleming BC, Beynnon BD, Renström PA, et al. The strain behavior of the anterior cruciate ligament during stair climbing: an in vivo study. Am J Sports Med 1999;15:185–191. 26. Fleming BC, Beynnon BD, Renström PA, et al. The strain behavior of the anterior cruciate ligament during bicycling. An in vivo study. Am J Sports Med 1998;26:109–118. 27. Beynnon BD, Johnson RJ, Fleming BC, et al. The strain behavior of the anterior cruciate ligament during squatting and active flexionextension. Am J Sports Med 1997b;25:823–829. 28. Heijne A, Fleming BC, Renström PA, et al. Strain on the anterior cruciate ligament during closed kinetic chain exercises. Med Sci Sports Exerc 2004;36:935–941. 29. Beynnon BD, Uh BS, Johnson RJ, et al. Rehabilitation after anterior cruciate ligament reconstruction. A prospective, randomized,

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30.

31.

32.

33.

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double-blind comparison of programs administered over 2 different time intervals. Am J Sports Med 2005;33:347–359. Fleming BC, Beynnon BD, Nichols CE, et al. An in vivo comparison between intraoperative isometric measurement and local elongation of the graft after reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1994b;76:511–519. Beynnon BD, Johnson RJ, Fleming BC, et al. The measurement of elongation of anterior cruciate-ligament grafts in vivo. J Bone Joint Surg 1994;76A:520–532. Beynnon BD, Uh BS, Johnson RJ, et al. The elongation behavior of the anterior cruciate ligament graft in vivo. A long-term follow-up study. Am J Sports Med 2001;29:161–166. Jonsson H, Karrholm J. Brace effects on the unstable knee in 21 cases. A roentgen stereophotogrammetric comparison of three designs. Acta Orthop Scand 1990;61:313–318.

34. Wojtys EM, Kothari SU, Huston LJ. Anterior cruciate ligament functional brace use in sports. Am J Sports Med 1996;24:539–546. 35. Wojtys EM, Loubert PV, Samson SY, et al. Use of a knee-brace for control of tibial translation and rotation. A comparison, in cadavera, of available models. J Bone Joint Surg 1990;72A:1323–1329. 36. Beynnon BD, Johnson RJ, Fleming BC, et al. The effect of functional knee bracing on the anterior cruciate ligament in the weightbearing and nonweightbearing knee. Am J Sports Med 1997a;25:353–359. 37. Beynnon BD, Pope MH, Wertheimer CM, et al. The effect of functional knee-braces on strain on the anterior cruciate ligament in vivo. J Bone Joint Surg 1992;74A:1298–1312. 38. Fleming BC, Renstrom PA, Beynnon BD, et al. The influence of functional knee bracing on the anterior cruciate ligament strain biomechanics in weightbearing and nonweightbearing knees. Am J Sports Med 2000;28:815–824.

Principles of Anterior Cruciate Ligament Rehabilitation INTRODUCTION Rehabilitation with anterior cruciate ligament (ACL) reconstruction has evolved considerably since the 1970s when intraarticular ACL reconstructions were first being performed. We have evolved from using casts on the leg for 6 weeks after surgery to no immobilization at all, from restricting weight bearing to encouraging weight bearing, from limiting range of motion to foster stability to emphasizing exercises to achieve full knee extension and flexion, and from restricting the return to sports until 1 year after to surgery to allowing participation in sports as soon as the patient is able to do so. We made this progression by systematically evaluating how different factors about surgery and what patients actually did during rehabilitation affected our patients’ results, and then we made improvements in our rehabilitation techniques to improve the overall outcome. Proper perioperative rehabilitation with ACL reconstruction is just as important as proper graft placement with surgery. We suggest that the orthopaedic surgeon needs to be intimately involved with the rehabilitation process to provide a consistent and effective program for patients to follow. It is most helpful to develop a close relationship with one or two physical therapists who will treat all the physician’s patients. The repetition of seeing many patients after ACL reconstruction done by the same surgeon allows the physical therapist to become familiar with what condition the knee will be in

after surgery, to learn the best way to treat any problems that arise, and to develop a rehabilitation program that prevents postoperative complications. Furthermore, when the surgeon has a good working relationship with a physical therapist, the physical therapist can do preoperative rehabilitation and testing to let the physician know when a patient is physically ready for surgery. The main complication after ACL reconstruction has been the limitation of knee range of motion or arthrofibrosis. Arthrofibrosis is defined as abnormal proliferation of fibrous tissue in and around a joint that can lead to loss of motion, pain, and muscle weakness. It is believed that arthrofibrosis is more common with the patellar tendon autograft, but it is found with all graft sources.1–4 We believe that improper perioperative rehabilitation, not the graft source itself, is the culprit for causing arthrofibrosis and that it can be avoided with all ACL reconstruction surgery if the proper rehabilitation is applied before and after surgery. Regardless of surgical technique or graft source, the goal for all patients after ACL reconstruction is to have a normal knee—one that has full range of motion, strength, and function. If the ACL reconstructed knee feels different than the contralateral normal knee, then the patient can function only at the level of the worst leg. Therefore symmetry between legs is the ultimate goal, not just ACL stability. People have symmetrical knees that are unique to the individual. In evaluating full range

65 CHAPTER

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Anterior Cruciate Ligament Reconstruction of motion, an important consideration is that 99% of women and 95% of men show some degree of hyperextension in their knees with averages of 5 and 6 degrees, respectively.5 Current data analysis of results of ACL reconstruction shows that any loss of knee extension or flexion is the major factor related to lower subjective scores at 10 to 20 years after surgery. Even the loss of 3 to 5 degrees of extension compared with the opposite knee can result in lower postoperative subjective scores.6 Thus the definition of full range of motion must depend on symmetry between the knees rather than the conventional practice of gauging knee motion against a fixed standard. To measure knee extension, the heel of the foot should be placed on a bolster so that the knee can fall into hyperextension (Fig. 65-1). The motion should be compared with the opposite normal knee. To get a kinetic feel for how easily the knee moves into hyperextension, the examiner can evaluate hyperextension by placing one hand above the knee to fix the femur and placing the other hand on the patient’s foot to lift the heel off the table (Fig. 65-2). Knee flexion can be measured by having the patient pull the heels toward the buttocks. When the knee is normal, the patient can kneel and sit back on the heels comfortably (Fig. 65-3). These evaluation tools should be used to determine whether the patient has full symmetrical knee motion. With the knowledge that full range of motion is essential—not only for athletes to function at a high level, but also for less active patients to be able to comfortably perform everyday activities such as squatting, kneeling, ascending, and descending stairs—we have designed our perioperative rehabilitation program with the principal goal of achieving postoperative symmetry between knees. The program begins at the time of the initial evaluation to include preoperative rehabilitation through the time the patient is fully recovered

FIG. 65-2 The examiner can get a kinetic feel for how easily the knee moves into hyperextension by placing one hand above the knee to fix the femur and placing the other hand on the patient’s foot to lift the heel off the table.

FIG. 65-3 Patients who have normal knee flexion can sit back on their heels without having any tilt in the hips.

and has returned to full activities. Patients follow a cascade of events that has few time constraints but must be followed sequentially to be most effective.

PREOPERATIVE REHABILITATION FIG. 65-1 The heel of the foot should be placed on a bolster so that the knee can fall into hyperextension. A goniometer is used to measure extension.

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After an acute ACL injury, the knee almost always develops a hemarthrosis. The hemarthrosis and inflammatory reaction cause the knee to lose range of motion and the leg to lose some quadriceps muscle strength. Patients typically

Principles of Anterior Cruciate Ligament Rehabilitation walk with a bent-knee gait and require crutch assistance. Preoperative rehabilitation is divided into two areas of emphasis. First, physically the patient should regain normal knee range of motion with very little swelling and should be able to walk with a normal gait. Secondly, the patient should be prepared mentally for the operative procedure and subsequent rehabilitation. The initial emphasis after an acute injury to the ACL is to control and then decrease the amount of swelling and pain. We use the knee Cryo/Cuff (Aircast, Summit, NJ), which combines cold with compression to reduce the hemarthrosis. The second goal of rehabilitation after an acute ACL injury is to restore normal knee range of motion, including full hyperextension equal to the noninjured knee. Obtaining full range of motion before surgery reduces the likelihood of motion problems postoperatively.7–9 A habit of performing full hyperextension exercises is important to develop preoperatively so that the exercises are easily a part of a daily routine after surgery. Several exercises and modalities are used to gain full normal hyperextension. Towel stretches are performed as a passive self-mobilization technique using a towel looped around the midfoot. The towel ends are held in one hand while the other hand is used to press and hold the thigh to the table. The towel is used to lift the heel of the affected lower extremity to end-range hyperextension by pulling the end of the towel upward toward the shoulder, where it is held for a count of 5 seconds, and then the heel is lowered back to the table (Fig. 65-4). For patients who have decreased quadriceps muscle control, an active heel-lift exercise can easily be added to the towel stretch. The active heel lift is accomplished by contracting the quadriceps musculature after the towel stretch is performed, trying to keep the heel of the affected leg elevated without using the towel to hold it in the air. Initially after injury, patients often display some degree of quadriceps

FIG. 65-4 Towel stretch exercise. The towel is used to lift the heel of the affected lower extremity to end-range hyperextension by pulling the end of the towel upward toward the shoulder.

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muscle inhibition, making a normal gait pattern difficult. It is important that the patient continue to try to actively elevate the heel to the height of the passive stretch. Passive extension in a seated position can be obtained by performing a heel prop on a towel or other type of bolster. The bolster should be high enough to elevate both the calf and the thigh of the affected extremity off the level of the table. A small weight can be added to the proximal tibia to facilitate full extension. The standing extension habit focuses on the patient’s ability to stand on the affected leg with the knee in a full hyperextended position. It is normal to stand on one leg with the knee locked into full hyperextension, and following an injury, patients will tend to favor their injured leg and stand on the nonaffected leg. To stand comfortably on one leg, patients must regain full hyperextension to rest on the passive joint structures. Forcing patients to stand on their affected lower extremity ensures that full hyperextension is regained and maintained. Regaining full knee flexion is achieved through performing wall slide and heel slide exercises. Wall slides are performed while lying supine with both legs extended up the wall. The heel of the injured leg is allowed to slide down the wall so that the knee is put into a flexed position with assistance from the noninjured leg until a stretch is felt in the knee. This is maintained for approximately 10 to 15 seconds; the leg is then extended back to the starting position, where the quadriceps muscle is squeezed and the leg is locked out for 5 seconds, and then the exercise is repeated. Heel slide exercises are started once the patient has at least 90 degrees of flexion. They are performed while in a long sitting position as the patient grasps the ankle of the involved extremity and passively pulls the leg into knee flexion. This is held for 10 to 15 seconds, and then the leg is allowed to fully extend back to a resting position. Patients should be instructed to watch for compensation in the hip during these flexion exercises. It is common for patients to substitute hip retraction in place of knee flexion when first trying to perform these flexion exercises. This should be avoided in order to maximize full flexion of the knee. Full weight bearing is allowed as tolerated by the patient, but a normal gait pattern must be achieved. Crutches are used to assist ambulation if the patient exhibits an antalgic gait pattern. Once a normal gait pattern is obtained, patients are allowed to ambulate without the use of any assistive device or prophylactic braces. Once the patient has achieved full range of motion, good leg control, and a normal gait with minimal swelling, he or she can begin a low-impact strength and conditioning program until surgery. Appropriate activities include the use of a stationary bicycle, elliptical machine, or stair-stepping machine, along with closed kinetic chain strengthening exercises for the 511

Anterior Cruciate Ligament Reconstruction lower extremity such as leg press, hip sled, and step-down exercises. Education on avoidance of high-risk activities that include twisting and rotation of the knee should be emphasized with the patient so that instability episodes prior to surgery can be avoided. We perform preoperative testing so that we can have objective measures for closely monitoring postoperative progress and to assist the patient in setting performance goals. The testing includes KT-1000 arthrometer testing of anterior translation, isokinetic strength at 180 degrees/sec and 60 degrees/sec, and isometric leg press test. The single leg–hop test is performed on the uninjured leg only. Strength is measured as a percentage of the involved lower extremity against the noninvolved lower extremity. Differences observed between the two lower extremities should be within 25% of each other before surgery when using an ipsilateral patellar tendon graft source. If the differences between the two legs are greater than 25%, a delay in surgery may be recommended so that the patient can work on strengthening the weaker lower extremity. When using a contralateral patellar tendon graft source, strength differences of greater than 25% are allowable as long as the patient has good quadriceps muscle control and normal ambulation. These data are used again postoperatively, starting at 1 month, to compare the athlete’s status with his or her preoperative strength and function. The overall goal of physical therapy in the preoperative phase is to control and decrease pain and swelling, restore full range of motion, aid in the resumption of a normal gait pattern, and initiate a strengthening program. By accomplishing these goals, the patient will present to the operative room for the reconstructive procedure with a normal-appearing and functioning knee except for the absence of the ACL.

Mental Preparation The second important factor in the preoperative preparation of an ACL reconstruction procedure is the mental preparation of the patient. Physical therapists follow patients closely and communicate with the surgeon regarding a patient’s mental and physical preparation for surgery, as the success of reconstruction depends on both factors.10 The physician must explain the nature of the injury to the athlete and family. The patient benefits from a detailed explanation of the operative procedure and the postoperative rehabilitation. The physical therapist should also review with the patient exactly what will be performed in all phases of the postoperative rehabilitation and how each phase of rehabilitation will be accomplished. The patient should approach the reconstruction procedure with a positive mental outlook. A “let’s just get it over with” attitude is not acceptable and can lead to less than superior 512

results, even with perfect surgical and rehabilitation techniques. The patient should arrive in the operating room ready to go with an attitude of looking forward to the reconstructive procedure and with an understanding of the postoperative rehabilitation.

POSTOPERATIVE REHABILITATION Ipsilateral or Contralateral Graft Rehabilitation after ACL reconstruction involves two different rehabilitation efforts with different goals. First is the rehabilitation of the knee as it pertains to the placement of the ACL graft intraarticularly. Second is the rehabilitation of the graft donor site. To do both effectively in the same knee, one rehabilitation effort must take precedence over the other to prevent the main complication of arthrofibrosis in the knee. Of utmost importance for the ACL graft in the short and long term is achieving full knee range of motion equal to the normal knee. This includes full hyperextension and the patient’s ability to kneel and sit back on his or her heels, as shown in Figs. 65-1 to 65-3. To rehabilitate the graft donor site, repetitive stress must be applied to the patellar tendon to stimulate it to regrow in size and strength. The sooner this repetitive stress can be provided, the more one can take advantage of the inflammatory response from harvesting the middle third of the patellar tendon. These two immediate goals for the ACL graft and the graft donor site are difficult to achieve simultaneously in the same knee without causing swelling and difficulty with achieving full range of motion. Therefore when a graft is harvested from the ipsilateral knee, the goal of achieving full range of motion takes precedence over rehabilitating the graft donor site. Our choice of whether to use an ipsilateral or a contralateral patellar tendon graft is based solely on the individual patient goals. The senior author used ipsilateral grafts for primary ACL surgery from 1982 to 1994 but used contralateral grafts during that time period for revision ACL reconstruction when patients had already had the patellar tendon graft used in their involved knees for primary reconstruction. We observed the ease of rehabilitation experienced by patients when the contralateral patellar tendon was used for revision surgery, especially with regard to the quick return of knee range of motion in the ACL reconstructed knee.10–12 Patients also reported that the ACL reconstructed knee felt normal to them very early after surgery, and they were able to return to their normal activities and sports very quickly. We initially began using the contralateral graft for primary ACL reconstruction in high-level athletes who wanted a quick return to sport. With its success and ease for achieving full symmetrical range of motion

Principles of Anterior Cruciate Ligament Rehabilitation and strength, we realized that the use of the contralateral graft was appropriate for any patient.13 We currently use the contralateral graft source for about 75% of patients. The rehabilitation program explained in this chapter can be followed regardless of the graft source or surgical technique used because the principles of rehabilitation and goals for patients are the same: to obtain knee symmetry for range of motion, strength, stability, and function. If the rehabilitation program provided follows the progression shown in Fig. 65-5, all the patient’s goals can be met.

Operative Considerations Postoperative rehabilitation begins in the operating room after graft placement. It is critical that full range of motion, including hyperextension and flexion so that the patient’s heel touches his or her buttocks, is achieved at this point to ensure the graft has not been overtensioned, resulting in a captured joint that prevents full motion. The success of the operation is initially dependent upon correct graft placement and then subsequently dependent upon providing proper rehabilitation to the ACL graft and the graft donor site in the knee. We apply a local anesthetic to the patellar tendon in the operating room. This allows for relatively painless flexion exercises to begin permitting the tendon to remain at its full

Cascade of events Pre-op rehab: No swelling, full ROM, good leg control

Surgery: Full ROM after graft placement and fixation

ACL rehab: Post-op–full ROM and no swelling Conflicting goals Donor site rehab: Increase tendon/leg strength

Proprioception and agility drills

Sport-specific drills

Competition FIG. 65-5 Effective rehabilitation involves following a progression of rehabilitation goals before and after anterior cruciate ligament (ACL) reconstruction. ROM, Range of motion.

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length. Later, heel-slide exercises and quadriceps muscle contractions during weight bearing and straight leg raises will similarly draw the patella proximally and stretch the tendon to its full length. The combination of these two exercises decreases patellar tendon stiffness and contracture, processes that could otherwise occur after graft harvest and cause donor site pain. Another important concept we use, allowing the patient to fully participate in phase I rehabilitation, is the avoidance of narcotic medications in the perioperative period. Although the occasional use of oral narcotic medication is necessary for some patients, parenteral narcotics decrease a patient’s ability to physically and cognitively participate in the exercise program. With the use of a ketorolac infusion, continuous cold/compression therapy, supplemental oral nonnarcotic pain medication, and immediate motion, narcotics can be avoided altogether in most instances. A regimen focused on preventing rather than treating pain increases both patient participation and satisfaction. Since instituting this pain prevention program, the average amount of nonnarcotic pain medication needed for patients has been 1.3 doses/day, with 73% of patients taking no pain medication by 6 days after surgery. Finally, in the operating room, external drains are placed in the region of the fat pad. Along with leg elevation and cold/compression therapy, external drains decrease the incidence and volume of postoperative hemarthrosis. Patients are kept in 23-hour outpatient observation to prevent hemarthrosis and allow initiation of immediate rehabilitation. Prior to leaving the operating room, antiembolism stockings are placed on both lower extremities. A Cryo/Cuff is placed on the ACL reconstructed knee, and an elastic sleeve with a frozen gel pack (Durasoft Patellar Tendon Wrap, DJ Orthopedics, Vista, CA) is placed over the contralateral donor side. Suprapatellar compression is not needed on the graft donor knee because graft harvest is an extraarticular procedure and there is no risk for an intraarticular effusion. As the patient arrives in the postoperative recovery area, the ACL reconstructed leg is placed into a continuous passive motion (CPM) machine set to move the knee from 0 to 30 degrees of flexion. CPM not only provides gentle motion, but more importantly also elevates the lower leg. The graft donor leg is also elevated on pillows to the same level to avoid increased strain on the lower back that can lead to lumbosacral pain. Both knees are elevated above the level of the heart (Fig. 65-6).

Outpatient Anterior Cruciate Ligament Surgery Most ACL surgery in the United States is performed on an outpatient basis, with the regular routine being that the patient goes home the day of surgery and then goes to a 513

Anterior Cruciate Ligament Reconstruction

Phase I: Early Postoperative Period

FIG. 65-6 After surgery, the anterior cruciate ligament (ACL) reconstructed leg is placed in a continuous passive motion machine so that the knee is elevated above the heart.

physical therapy unit a day or so after surgery to begin physical therapy. We believe that by having the patient stay in the hospital overnight, we have the means to prevent a hemarthrosis from forming in the knee. The patient’s ACL reconstructed leg remains elevated with the cold compression device on the knee except when specific exercises are being performed. Preventing hemarthrosis is key for controlling pain, preventing a quadriceps muscle shutdown, and achieving full knee range of motion. When the patient is sent home a few hours after surgery, the activity of getting out of bed, getting to a car, riding home, and getting into the house causes the knee to swell, which is contrary to the primary goal of preventing a hemarthrosis after surgery. Then when the patient is required to leave the house for physical therapy a day or so after surgery or several times in the first week after surgery, a knee hemarthrosis is almost inevitable. We believe that the success of our rehabilitation program may lie in our requiring our patients to remain in the hospital overnight, receive patient education before going home, and remain on bedrest for the first 5 days after surgery. If the surgeon must do ACL reconstructions on an outpatient basis and send the patient home the day of surgery, major swelling in the knee may still be able to be prevented by having the patient understand and perform rehabilitation exercises at home. The physical therapist can communicate with the patient before surgery and daily after surgery to monitor the patient’s progress, and the patient could be actively treated by the physical therapist 5 to 7 days after surgery. This approach does require that the surgeon work with physical therapists who fully understand the rehabilitation program, that patients undergo preoperative rehabilitation and patient education, and that the physical therapist contact the patient daily by phone to monitor the patient’s progress.

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Phase I rehabilitation continues on arrival to the outpatient hospital unit where targeted physical therapy begins. The patient and the family caregiver are given an exercise diary that outlines the rehabilitation exercises to be performed. Checkmarks or measurements are placed in boxes next to each exercise as they are completed. This practice aids in compliance by giving the patient a visual reference to specific exercises. Another additional benefit of performing preoperative rehabilitation is that the patient can become familiar with the postoperative exercises to be performed, thus reducing the chance of confusion or improper exercise technique. We start with exercises for range of motion with assisted flexion in a CPM machine for the ACL reconstructed leg. The patient is instructed to maximally flex the CPM to 125 degrees and hold this position for a period of 3 minutes. The CPM is progressed to maximum flexion slowly and as tolerated by the patient. Heel-slide exercises are performed next for both the ACL reconstructed leg and the contralateral donor site leg. A yardstick is positioned next to the leg with the zero end aligned with the end of the heel (Fig. 65-7). The yardstick provides a visual cue for patients to easily monitor the progress of knee flexion. Next, the patient flexes the knee with the help of a towel looped under the thigh until further flexion becomes difficult. Terminal flexion is held for 1 minute. The number of centimeters the heel has traveled is recorded. This number makes it easy for the patient and physical therapist to communicate changes in range of motion over the phone during the first week when the patient is at home. Flexion in the ACL reconstructed leg should be approximately 110 to 120 degrees immediately postoperatively. Flexion in the contralateral graft donor knee should be full and equal to preoperative measurements because harvesting the graft alone does not cause swelling and the patellar tendon has been stretched to maximal length while still in the operating room. The patient then props both legs into extension with the heels resting on the Cryo/Cuff canister, allowing for any hyperextension. A small 2.5-pound weight is placed just distal to the incision on the ACL reconstructed leg. This exercise is maintained for 10 minutes. Following the heel prop exercise, the patient performs three to five knee thunk exercises on each knee, in which the patient flexes the knee to a height of several inches and then allows the leg to relax and “thunk” into hyperextension. Thunk exercises can be difficult for patients to perform on the ACL reconstructed leg at first for fear of damaging the ACL reconstruction. Typically, therefore, thunk exercises are performed first on the graft donor leg so that the patient understands how hyperextension feels. Five to ten towel stretch exercises are performed for each leg as

Principles of Anterior Cruciate Ligament Rehabilitation

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FIG. 65-7 A yardstick is positioned next to the leg with the zero end aligned with the end of the heel. With heel-slide exercises (A), the patient can easily monitor the amount of flexion as it corresponds to the number of centimeters on the yardstick (B).

described previously. Active heel-lift exercises are combined with the towel stretch to achieve good quadriceps control (Fig. 65-8). Straight leg raise exercises for leg control are performed on both legs by having the patient first initiate a quadriceps muscle contraction and then focus on maintaining the knee in a locked-out position while lifting the leg so that the heel is 2 to 3 feet in the air above the mattress (Fig. 65-9). To provide high repetition stress to the graft donor site while still remaining in bed, we use the Shuttle (Contemporary Design, Glacier, WA). The Shuttle is a light-weight, low-resistance portable leg press machine (Fig. 65-10). Resistance is provided by the placement of weighted rubber cords, each adding additional resistance. This weight is applied during both the concentric and eccentric movements. Twenty-five repetitions with one cord (7 pounds) are then completed with the emphasis on slow, controlled motion.

FIG. 65-9 The straight leg raise exercise facilitates good leg control.

FIG. 65-10 The Shuttle machine provides a means for the patient to perform low-resistance leg press exercise while still remaining in bed.

FIG. 65-8 Active heel-lift exercise. After the patient does a towel stretch exercise, he or she contracts the quadriceps muscle to actively lift the heel into extension.

Following these exercises, the Cryo/Cuff and gel pack are applied to the ACL reconstructed knee and graft donor knee, respectively, and the ACL reconstructed leg is placed back into the CPM set from 0 to 30 degrees, with the graft 515

Anterior Cruciate Ligament Reconstruction donor leg again propped up on pillows. The water in the Cryo/Cuff is changed once every waking hour. The patient is confined to bedrest with the use of a portable urinal and bedpan if needed. The patient may ambulate at this time but does so at the risk of developing a hemarthrosis. The drains are removed from both knees the following morning, and an identical set of exercises is performed. At the end of this session, the patient ambulates for the first time. This is accomplished carefully to avoid a fall. First, the patient sits at the edge of the bed and, when it is clear that the patient is steady and not dizzy, standing is encouraged. Standing is allowed for a few minutes, with the clinician close by to make sure a vasovagal episode does not occur. Next, the patient is instructed to shift his or her weight over to the ACL reconstructed leg and lock that leg into hyperextension with a quadriceps muscle contraction (Fig. 65-11). The patient then ambulates to the door of the room and back using small steps and focusing on a point high on the wall in the direction of ambulation. Patients are allowed to ambulate with full weight bearing as tolerated; however, the use of

FIG. 65-11 Standing habit. The patient is instructed to stand on the anterior cruciate ligament (ACL) reconstructed leg so that the leg is extended into full hyperextension.

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crutches or a walker is allowed for patients who are unsteady on their feet and are at risk of falling. Patients are released home from the hospital the day after surgery. Before release from the hospital, each patient must demonstrate full extension of the ACL reconstructed leg equal to the contralateral graft donor leg, flexion of at least 110 degrees on the ACL reconstructed leg, full or near-full flexion of the graft donor leg, the ability to lift both legs independently with quadriceps muscle contraction, the ability to ambulate independently, and a complete understanding of the home exercise program. Patients are advised that flexion may decrease from the previous day in the ACL reconstructed knee, but the flexion obtained initially after surgery should return gradually by 2 to 3 days after surgery. In general, patients are counseled against pushing flexion too hard in this period, as maintaining full extension is more important. Flexion in the contralateral graft donor knee should remain full. Following discharge from the hospital, physical therapists call patients at home daily for the first week to monitor progress and answer questions that might arise. The previous list of exercises is carried out five to six times daily with the exception of the Shuttle, which is used three times daily and on the contralateral donor leg only. Patients are instructed not to use the Shuttle at the first morning exercise session and to discontinue its use until further instructed by the physical therapist if the knee becomes too sore at the graft site or if they begin to lose knee flexion on daily measurements. Daily flexion measurements are made using the yardstick, measuring the distance the heel travels on both knees. Barring these events, patients are allowed to increase the number of repetitions performed during each session on a daily basis, up to 10 additional repetitions per day. When 100 repetitions become easy for the patient, an additional cord can be added for progressive resistance, but the number of repetitions is decreased to 50 per session. The patient is allowed to then begin progressing up to 100 repetitions again with the increased weight. If flexion in the graft donor leg starts to decrease (as measured by yardstick daily), the patient is advised to either decrease the Shuttle exercise weight, frequency, or both until full flexion returns in the graft donor leg. In the ACL reconstructed leg, knee extension is emphasized more than flexion during this phase. If the amount of knee extension plateaus or decreases, the amount of exercise to increase flexion should be deceased accordingly. Patients are warned that exercises will become more difficult at day 2 or 3 after surgery before gradually improving as a result of the body metabolizing the ketorolac medication from the hospital. During the first week after surgery, patients are allowed out of bed only two to three times daily for bathroom needs.

Principles of Anterior Cruciate Ligament Rehabilitation

Postoperative Rehabilitation Phase II The first postoperative visit is at 1 week after surgery. Rehabilitation remains unique to each leg. The patient continues to work on maintaining full extension of the ACL reconstructed knee while concentrating on patellar tendon remodeling and regrowth in the graft donor knee through the use of strengthening exercises and maintaining full flexion. The primary goal is full extension of the ACL reconstructed leg; 110 degrees of knee flexion is a secondary goal and represents the average flexion in this period. No patients should have less than 90 degrees of flexion. Full flexion is expected in the graft donor knee. Next, quadriceps muscle control is assessed. Each patient should be able to perform a straight leg raise without a lag and perform an active heel lift, contracting the quadriceps muscle with the knee in a hyperextended position. The patient should also have sufficient quadriceps muscle control to ambulate stairs using only the handrail for balance. If achieving an active heel lift through voluntary contraction is not possible, the condition may be a result of quadriceps muscle inhibition. Clinically, this condition manifests itself in a poor gait pattern. Stance and gait training includes using a mirror to help the patient visualize and understand the correct position of a hyperextended knee in stance, as well as working on gait using a decreased step length and focusing on terminal extension during initial contact with overemphasized heel contact. Whenever sitting, the patient should be performing a heel prop to work on passive extension on the ACL reconstructed leg. Whenever standing, weight should be shifted to the ACL reconstructed leg locking the knee into hyperextension. Towel stretches are continued through this phase. The importance of full symmetrical hyperextension cannot be overemphasized. If asymmetrical hyperextension is noted and not correctable by the end of this follow-up appointment, then a more vigorous technique to regain full extension is needed. These techniques will be explained later in this chapter with regard to problems with rehabilitation. Knee flexion exercises are also implemented for the ACL reconstructed knee. The goal for the end of week 2 is 120 degrees. Exercises including heel slides and wall slides are routinely given. Flexion hangs, which involve holding the posterior thigh with the hip flexed to 90 degrees and allowing gravity to passively flex the knee, can be added at this point for patients whose flexion is less than 120 degrees. All range of motion exercises are performed two to four times a day during the intermediate phase. During week 2, the CPM is discontinued while cold/ compression therapy continues. The cold/compression device is used by the patient as needed throughout the day to control swelling, and continued use throughout the night is

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encouraged but is not required if swelling is adequately controlled. Shuttle exercises for the contralateral graft donor leg are progressed as described previously as long as the patient retains full flexion. Front step-down exercises are initiated at this point, and patients start with 50 repetitions three times per day on the 2-inch step. This is progressed in a similar manner to the Shuttle until the patient is performing 100 repetitions on the 2-inch step. The patient independently advances this progression based on the amount of donor site soreness. The step box, a hinged, foldable device, allows step exercises from heights up to 8 inches. Patients are instructed to perform front step-down exercises, focusing on quality of form and technique rather than quantity of the number performed (Fig. 65-12). Balancing on the graft donor leg with the hands placed on the hips, the patient lowers the heel of the opposite leg to the floor in front of the step box until it touches the floor. It is important for the patient to keep the pelvis in a neutral position during the descent phase to prevent compensation from the hip musculature. If the patient continues to maintain good knee motion and avoid joint effusion during the second postoperative week, he or she is allowed to increase the time spent upright

FIG. 65-12 Step-down exercise provides light strengthening. The patient stands on the step and lowers the heel of the opposite leg to the floor while keeping the pelvis in a neutral position.

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Anterior Cruciate Ligament Reconstruction by 1 to 2 hours per day. Patients can usually attend school or work half-days starting about 1.5 weeks postoperatively. By day 10 to 12 postoperatively, if motion remains good and effusion is not an issue, patients are allowed to be up for 1 full day with brief periods of elevated rest as needed. The second postoperative visit takes place 2 weeks after surgery. Knee range of motion, gait, and quadriceps muscle control are again carefully examined. By this time, patients should report that they are back to performing their full normal activities of daily living independently without difficulty or other compensatory strategies. In the ACL reconstructed knee, 120 degrees of flexion is expected in addition to full extension. Effusion should be well controlled. Excessive effusion is indicative of an overly intense activity level and should be addressed immediately. Patients should be instructed to return to a decreased level of activity with the leg elevated on pillows and continuous usage of the Cryo/Cuff until the swelling level has returned to an expected baseline amount of swelling. During this time, patients still perform range of motion exercises. Full flexion and extension in the graft donor knee should be maintained. Normal gait should be demonstrated, and patients should be able to ambulate up and down stairs without holding onto the handrail. When a graft from the contralateral knee is used, the goal of rehabilitation for the graft donor site between weeks 2 and 4 is remodeling and regrowth of the donor patellar tendon through high-repetition, low-resistance exercise carried out several times daily. These exercises are essential to avoid long-term donor site pain. Patients are instructed in leg press and knee extension exercises, as well as continuation of the step-down exercises. These exercises should not be performed on the ACL reconstructed leg until full knee range of motion is obtained. Typically, patients are asked to start with half their body weight or less for the leg press and 2 to 5 pounds with the knee extension exercise. These exercises can be performed every other day to ensure that the graft donor site does not become overly sore. Three to five sets of 10 to 12 repetitions of each exercise are usually sufficient. The weight used for both exercises can be progressed slowly as the patient improves in strength. In our experience, patients can easily overexert themselves with either the leg press or the knee extensions and make the donor tendon site sore. If the patient develops soreness that persists and is not decreased with cryotherapy, these exercises may need to be discontinued for a period of time. Most important is that the patient continues to demonstrate full range of motion with continued strength improvement without developing unrelenting donor site pain. Step-down exercises are progressed during this visit as able so that they are providing an appropriate challenge to the patient. If the patient has maximized the number of 518

repetitions during the second week (100 reps, four to six times per day), he or she is allowed to progress up to the 4-inch step; otherwise the patient stays at 2 inches and continues to progress on the 2-inch step. The number of repetitions is decreased to 50 on the 4-inch step, and the patient can progress this number back up to 100 per session as able. Once 100 repetitions is reached on the 4-inch step, the patient is allowed to go up to the 6-inch step, again reducing the number of repetitions performed to 50 and progressing the number performed as able. Soreness in the tendon should be relieved with cryotherapy, not interfere with normal gait or stairs, and be absent from the tendon prior to the next session. If the graft donor leg begins to become overly sore or if a decrease in knee flexion is noticed during exercises, the graft donor leg strengthening intensity should be decreased until full flexion returns. It remains vital to maintain full extension of the ACL reconstructed knee and to make progress in flexion. By the 1-month visit, the goal is for patients to be able to comfortably sit on their heels with their ankles in maximal plantarflexion, indicative of full knee flexion. Motion exercises for the ACL reconstructed knee remain the same as weeks 1 and 2. Extension habits are again reviewed and reinforced because some patients have trouble integrating them into their daily routine.

Postoperative Rehabilitation Phase III: Advanced Strengthening Four weeks after surgery, the patient returns for a full round of strength testing, as well as KT-1000 arthrometer evaluation. The single leg–hop test is not included in this visit usually because most patients have not had a full return in confidence and are not ready to return to sports activities. The results of these tests are helpful to assess the patient’s progress over the previous 4 weeks and to develop a plan for further activity. When an ipsilateral graft is used, patients can begin strengthening the ACL reconstructed leg if the knee has full range of motion and very little swelling. The exercises and progression for strengthening the ACL reconstructed leg are the same as those prescribed for the graft donor leg, with the concentration on single leg strengthening exercises as described previously. The patient adjusts the amount and intensity of the strengthening exercises based on whether he or she experiences any decrease in range of motion or an increase in knee swelling. Typically, patients have about 60% quadriceps muscle strength in the ACL reconstructed leg compared with the normal leg. Patients should perform single leg strengthening until they achieve 90% strength in the ACL reconstructed leg; then they can continue with bilateral leg strengthening exercises.

Principles of Anterior Cruciate Ligament Rehabilitation When a contralateral graft is used, the recovery of strength to preoperative normal levels is not as important as symmetry between the ACL reconstructed leg and the graft donor leg. For a patient doing well, isokinetic strength in the graft donor leg should be within 10% of the ACL reconstructed knee. The ability to return to activities depends on the strength of the graft donor knee, the presence of full motion in both knees, and the lack of an effusion in the ACL reconstructed knee. If symmetrical quadriceps muscle strength (differences of less than 10% on testing) is achieved, the patient begins bilateral strengthening and conditioning exercises. Leg press, knee extension, and step-down exercises are now performed on both legs, with the patient doing the exercises with each leg independently and continuing to progress the intensity by adding weight as able. If the quadriceps muscle strength is not within 10% between legs, the patient continues with strengthening the graft donor leg only. Low-impact conditioning, including stationary bike, stair-stepping machine, or elliptical trainer, is added. These activities need to be started very slowly and cautiously as the amount of swelling in the ACL reconstructed knee is monitored. Typically, most patients tolerate starting with 10 minutes every other day and increasing to 20 to 30 minutes over the course of the next 4 weeks. Patients who have had an ipsilateral graft need to know that these low-impact conditioning exercises will not help to strengthen the leg. Given that both legs are involved, it is difficult for patients to use both legs equally when there is more than a 10% discrepancy in strength between legs. Therefore these exercises should not replace the specific single leg exercises prescribed. Straight-line forward and backward jogging, lateral slides, and crossover agility steps can be introduced. Shooting baskets or other individual noncompetitive sport-specific drills are performed as tolerated. These agility activities are done in controlled situation and do much to keep athletes motivated toward their goals, but again these activities should not replace specific strengthening exercises. No competitive situations are allowed at this time.

Postoperative Rehabilitation Phase IV: Return to Competition There are no strict guidelines as to when a patient may return to sports. Patients return to the clinic for follow-up testing and adjustment to their home exercise programs and activity level regularly at 2-, 4-, and 6-month visits. Rehabilitation continues to be monitored as the patient returns to his or her preoperative, fully competitive level of activity. Symmetry, in the form of equal strength, full range

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of motion, and joint effusion, is evaluated at each visit. Once symmetry is achieved between both knees, the level of activity can be increased slowly to include return to sports activities. During the return to full activities, the patient must monitor swelling and range of motion daily. If swelling occurs or the knee loses any extension or flexion, the patient must back off on activities, ice the knee, and perform range of motion exercises. Increased activity causes stress on the ACL graft, which is desirable because it stimulates the graft to mature. However, the maturation process in the ACL graft causes it to become stiffer, and patients must fully extend and flex the knee several times daily to keep the ACL graft stretched and to prevent capturing the knee. When the patient first returns to athletic practice or competition, it should be done on an every-other-day basis. The initial return to activities is similar to that of a weightlifting program. The athlete, while doing the activity, may feel and perform normally but may become quite sore afterward. Thus the athlete can practice as usual one day but then needs to take a day off to allow the knee (or knees) to recover. We have found that coaches sometimes do not understand this process and put pressure on the athlete to practice and compete every day. It is important for the physician and physical therapist to communicate directly with the coach to explain that having athletes practice every other day will allow them to do the sport with better quality when they are practicing and to eventually return to full competition faster instead of having long-term problems with knee soreness that is difficult to resolve with everyday activity.

COMMENT Some physicians believe that patients should not be allowed to return to competitive sports until 6 months to 1 year after surgery because they believe that it takes that long for the ACL graft to mature and that graft maturation is what will prevent ACL graft rupture in the future. There is nothing magical about an arbitrary time of 6 months that makes it safe for a patient to return to sports. We have found that it takes patients 3 to 4 months of playing their sport before they feel that the knee has returned to normal. Interestingly, patients who do suffer an ACL graft rupture do so after they have been back to playing and are at the level of feeling normal, and not during the first few months of playing. We have not found a specific time after surgery where the ACL graft is most vulnerable. The average time of ACL graft tear is 2.1 years (range, 3 months–9.2 years) after surgery, and the time of graft tear is equally distributed over that time.14

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Anterior Cruciate Ligament Reconstruction Regardless of the surgeon’s philosophy for returning patients back to sports, we believe that the rehabilitation should be done such that patients can regain their normal knee range of motion and strength as soon as possible after surgery. There is no reason to limit full hyperextension and full flexion in the knee at any time after surgery if the ACL graft is placed properly in the knee. As previously explained, the immediate goal after surgery is to limit a knee hemarthrosis and regain full knee range of motion before beginning an aggressive strengthening routine. Throughout the entire rehabilitation process, maintaining full knee range of motion is emphasized and takes precedence over other rehabilitation goals. Knees that have full range of motion respond better to strengthening exercises. Furthermore, patients who have knees with normal range of motion with no swelling are able to perform their normal everyday activities without concern. Although patients can have normal-feeling knees by 1 to 2 months after surgery with the described rehabilitation program, the physician can still restrict the patient from returning to sports until the time he or she feels is appropriate. There is no reason, however, to limit the patient from achieving the other rehabilitation goals.

SUMMARY Proper rehabilitation before and after ACL reconstruction is just as important as performing a technically sound surgical procedure. The principles outlined in this chapter, if followed closely, allow patients to achieve the best possible outcomes after surgery. Paramount to regaining full function is that patients obtain full symmetrical knee range of motion and strength. The progression described in this chapter allows patients to achieve these important goals.

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References 1. Chang SK, Egami KD, Shaieb MD, et al. Anterior cruciate ligament reconstruction: allograft versus autograft. Arthroscopy 2003;19:453–462. 2. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 3. Ejerhed L, Kartus J, Sernert N, et al. Patellar tendon or semitendinosus tendon autografts for anterior cruciate ligament reconstruction? A prospective randomized study with a two-year follow-up. Am J Sports Med 2003;31:19–25. 4. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83B:348–354. 5. DeCarlo MS, Sell KE, Shelbourne KD, et al. Current concepts on accelerated ACL rehabilitation. J Sport Rehab 1994;3:304–318. 6. Shelbourne KD. Unpublished data, 2005. 7. Mohtadi NG, Webster-Bogaert S, Fowler PJ. Limitation of motion following anterior cruciate ligament reconstruction. A case-control study. Am J Sports Med 1991;19:620–624. 8. Shelbourne KD, Patel DV. Timing of surgery in anterior cruciate ligament-injured knees. Knee Surg Sports Traumatol Arthrosc 1995;3:148–156. 9. Shelbourne KD, Wilckens JH, Mollabashy A, et al. Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation. Am J Sports Med 1991;19:332–336. 10. Rubinstein RA Jr, Shelbourne KD, VanMeter CD, et al. Isolated autogenous bone-patellar tendon-bone graft site morbidity. Am J Sports Med 1994;22:324–327. 11. Shelbourne KD, Thomas JA. Contralateral patellar tendon and the Shelbourne experience. Part 1. Revision anterior cruciate ligament reconstruction and rehabilitation. Sports Med Arthrosc Rev 2005;13:25–31. 12. Shelbourne KD, Thomas JA. Contralateral patellar tendon and the Shelbourne experience. Part 2. Results of revision anterior cruciate ligament reconstruction. Sports Med Arthrosc Rev 2005;13:69–72. 13. Shelbourne KD, Urch SE. Primary anterior cruciate ligament using the contralateral autogenous patellar tendon. Am J Sports Med 2000;28:651–658. 14. Shelbourne KD. Unpublished data, 2006.

The Stability-Conservative Anterior Cruciate Ligament Reconstruction Rehabilitation Protocol INTRODUCTION The primary goal of anterior cruciate ligament reconstruction (ACLR) is to restore stability without sacrificing mobility or strength. The primary purpose of ACLR rehabilitation is to restore mobility and strength without sacrificing stability. It is the central hypothesis of this chapter that overly aggressive rehabilitation is both unnecessary and potentially sacrifices knee stability. The stability-conservative rehabilitation protocol can best be summarized as follows: Avoid graft strain and abrasion while restoring motion and strength in the early postoperative period. It is based on the following premises and principles: Premises 1 Stability after ACLR can be compromised by an overly aggressive rehabilitation protocol. 2 Full motion and strength can reliably be obtained with a less aggressive approach designed to minimize ACL strain and abrasion in the graft in the first 3 postoperative months when the fixation points and the graft are weak. 3 No fixation device will ever be able to guarantee that grafts will not slip and/or elongate during healing if they are strenuously and repetitively strained prior to tunnel healing. 4 Because only about half of reconstructed knees currently achieve stability that is

roughly symmetrical with the other knee (see later discussion), it is important to not sacrifice stability in the name of faster rehabilitation.

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Principles 1 Restoration of full extension and almost full flexion should be aggressively pursued immediately after surgery, but not hyperextension and hyperflexion, which strain the graft. 2 Strengthening, especially of the quadriceps, must be performed only within safe arcs of knee motion to avoid compromising stability. 3 Cyclical loading should be avoided within the first 3 postoperative months to avoid strain and tunnel abrasion of the ACL graft beyond that found during activities of daily living.

HISTORY Until the late 1980s, ACL rehabilitation was rendered cautiously on the theory that stability was fragile and strain in the graft needed to be minimized in the early postoperative period to avoid loss of stability. It was well known that grafts lose much of their tensile strength in the first few postoperative months.1–3 It was recognized that grafts require time to heal into bone tunnels before which they are subject to loosening2,4 (see Chapter 56). Finally, it was also known that quadriceps contractions in the terminal 50 degrees of extension exerted a powerful anterior 521

Anterior Cruciate Ligament Reconstruction translational moment on the tibia that strains the ACL.5,6 As bone–patellar tendon–bone (BPTB) grafts became popular during the 1980s, it became apparent that many knees became stiff and had prolonged quadriceps weakness. This stiffness was potentially a worse problem than the laxity of ACL deficiency. A stable but stiff knee was more likely to be worse than an unstable knee. In 1990 Shelbourne published his classic paper7 introducing accelerated rehabilitation. This challenged the then-accepted view that grafts needed to be carefully protected during the first few postoperative months. He stated that his patients who were somewhat noncompliant with his postoperative restrictions and were more active had no greater incidence of instability than the compliant patients. However, these more active patients had less stiffness and weakness. He postulated that “accelerated” early aggressive rehabilitation was thus not harmful and also necessary to ensure restoration of motion and strength. Based on these observations he developed his accelerated rehabilitation protocol, which is currently used in some form by most ACL surgeons.

SYMMETRIC STABILITY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IS NOT ASSURED Many surgeons commonly use exercises such as cycling and squats that cause quadriceps contractions in the terminal 50 degrees of extension in the early postoperative period. As shown by the research of Beynnon and others8,9 (see Chapter 64), these activities exert a significant strain on the ACL. The accelerated rehabilitation protocol states that stability will not be compromised by such ACL-straining activities if the surgery is properly performed. Yet, as shown in the most recent meta-analysis10 to review all such papers and as discussed elsewhere in this book (see Chapter 69), symmetrical stability after ACLR is currently achieved in only about half of all reconstructed knees, even in the hands of the very experienced ACL surgeons. Accelerated rehabilitation was developed, in particular, to overcome stiffness and weakness in BPTB patients. However, mean KT-1000 scores for BPTB from the literature showed that 34% of reconstructed knees had more than 2 mm of increased laxity than the normal knee, the stability level usually seen with a partially torn ACL. Of the 66% that were within 2 mm, it is estimated that one-fourth or 17% had exactly 2 mm of increased laxity. Thus 34% þ 17% or 51% in all had 2 mm or more increased laxity. This leaves only about half with restoration of stability that is the same as the opposite knee. In addition, 5.9%, or roughly 1 in every 17 knees, had abnormal stability (i.e., a failed graft). Thus some of the most experienced knee surgeons in the world in the current

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literature are only restoring even approximately symmetrical stability—within 1 mm of the other knee—to half of the operated BPTB knees. Half have stability at a level seen with a partially torn ACL or worse.

WHY PROTECT THE GRAFT IN THE FIRST 3 MONTHS POSTOPERATIVELY? Fixation Point Healing The studies of Milano and others,2 which are discussed in Chapter 56, show that soft tissue healing into tunnels can take 2 months or longer. During this time, strain on the graft has the potential to make the fixation slip and the graft lax. This healing occurs several weeks earlier in BPTB grafts than in soft tissue grafts.

Graft Strength Grafts undergo cell death, edema, and then revascularization in the first few months postoperatively (see Chapter 55). During this time the graft loses approximately 75% of its strength. Thus both fixation strength and interstitial strength are compromised during the first few postoperative months. Strain of the graft can induce laxity by both fixation point slippage and graft elongation from plastic deformation. Cyclical loading has the potential to damage the graft by tunnel abrasion before tunnel healing has occurred.

MUSCULAR INHIBITION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Effusions,11–13 ACL injury,14,15 and knee pain16,17 have all been shown to have an inhibitory effect on knee musculature, especially the quadriceps, apparently through afferent inhibition of motor neuron activity. This means that during roughly the first 3 postoperative weeks, when most patients have a large hematoma and some knee pain, it may be difficult or impossible to generate large-enough muscle contractions to strengthen or effectively prevent atrophy. In the past when we attempted to begin strengthening immediately after surgery, we noticed that strength gains did not occur, probably for this reason. In addition, the exercises produced significant patient discomfort. For this reason we no longer begin strengthening until roughly the end of the third postoperative week for isometric quadriceps and later for other muscle groups in which atrophy is less of a concern.

The Stability-Conservative Anterior Cruciate Ligament Reconstruction Rehabilitation Protocol

CYCLICAL LOADING DOES CAUSE LAXITY Every study that has looked at this subject has shown that cyclical loading induces elongation of the graft–fixation construct. These studies typically show several millimeters of elongation.18–20 The best such study showed 1 mm after the first 100 cycles. Many of these studies look only at the first 1000 cycles.18 One thousand cycles is equal to the number of steps taken in less than 1 week of normal activity and less than 1 week of cycling during rehabilitation. It is highly likely that this elongation would further increase if more cycles were performed. It is important to realize that only 2 mm of elongation from cyclical loading is enough to change the side-to-side difference from –1 mm to –3 mm, converting good stability to the stability level seen in a partial ACL tear.

WHY AVOID HYPEREXTENSION? The studies of Beynnon (see Chapter 64) have shown that hyperextension strains the graft significantly. Thus hyperextension should be avoided for that reason. Also, hyperextension is not used during normal gait. In our large long-term study21 of patients after hamstring (HS) ACLR, patients were told to avoid hyperextension for the first year after surgery. At follow-up (as long as 8 years postoperatively) most patients had recovered symmetrical hyperextension. All patients had essentially full extension. No patient experienced any clinical motion deficit. Thus nothing was lost by avoiding hyperextension in our rehabilitation protocol, and we believe a potential stability benefit was obtained by avoiding the strain that hyperextension would have exerted on the graft. Others have thought that achieving full hyperextension is necessary to achieve full painless motion. We have not found this to be the case with our patients. We should point out, however, that our experience is limited to soft tissue grafts. It is possible that hyperextension may provide some benefit for BPTB grafts that it does not for HS grafts.

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Either or both of these phenomena can produce pain from patellar tendonitis or patellar chondromalacia, respectively. Thus obtaining full extension is the single most important aspect of ACL rehabilitation because it allows painless walking. We obtain full extension via an extensional force applied to the supine patient’s proximal tibia from the physical therapist and/or the patient’s family members, as well as various stretching exercises. We do not use or allow quadriceps contractions to help achieve it because quadriceps contractions in terminal extension result in a powerful strain on the ACL (Fig. 66-1).

WHY AVOID FULL FLEXION? Flexion of 110 degrees is necessary to descend stairs. We work to achieve flexion of 115 to 120 degrees to provide a flexion reserve in this regard. However, we avoid hyperflexion in the first 6 months because it increases strain in the graft6 and serves no functional purpose. Again, our longterm follow-up study showed that patients almost always regained full extension on their own after their discharge at a later time, when the graft was able to withstand the powerful strain thus induced.

THE TIMING OF STRENGTHENING IN PHYSICAL THERAPY In most patients we do not begin HS strengthening until the fourth month, when gains occur more quickly. In most cases we have had no difficulty achieving full HS strength by their full activity release at the 6-month postoperative mark. We believe that it is wasteful of time and resources for patients to come to the therapy clinic continuously for 6 months. Therefore we take a break from the time when

WHY INSIST ON FULL EXTENSION AND HOW TO ACHIEVE IT Full extension is necessary to avoid walking on a flexed knee. During full extension the quadriceps is lax, thus diminishing tension on the patellar tendon and avoiding compressive force on the patella. If full extension is not achieved, causing the patient to walk on a flexed knee, there is greatly increased patellar tendon tension and patellofemoral compressive force.

FIG. 66-1 Passive extension by the therapist in the clinic and the family at home, avoiding hyperextension, is very effective in regaining full extension.

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Anterior Cruciate Ligament Reconstruction full motion is achieved (usually 2 weeks postoperatively) until the end of the third month or beginning of the fourth. This gives the patient 3 months to achieve full strength before being released after 6 months, which is usually more than adequate. It also concentrates their therapy visits at a time when increased healing and reduced inflammation provide greater stability and faster strength gains.

QUADRICEPS STRENGTHENING Quadriceps contraction, whether open or closed chain (see Chapter 64), strains the ACL significantly from 0 to roughly 50 degrees of flexion depending on the study.22,23 Contrary to prior thought, Beynnon (see Chapter 64) has shown that this strain is not decreased in closed chain exercises relative to open chain. We do not begin quadriceps strengthening until 110 degrees of knee flexion is obtained because strengthening of a muscle can decrease its elasticity and thus could inhibit attempts to achieve flexion. However, when 110 degrees of flexion is achieved (usually by the end of the second week), we believe it is safe to begin protected quadriceps strengthening. To avoid cyclical loading we use an isometric exercise called the “wall push” (Fig. 66-2). This produces an isometric quadriceps contraction with the knee flexed 90 degrees. This 90-degree mark is easy for patients to remember when doing the exercise on their own. Patients lie on their back on the floor and flex the hips and knees to 90 degrees, putting the flat foot on the wall. A family member or friend holds a bathroom scale between the foot and the wall to record the compressive pressure achieved. This can be charted at home to mark the progression of strength and gives the patient a goal to achieve and exceed as strength increases. Only the operated extremity is strengthened to promote symmetry between the legs. This exercise has the benefit of being able to be done entirely at home, without clinic visits, once the exercise has been properly demonstrated to the patient.

HAMSTRING STRENGTHENING Leg curls are the primary exercise and are usually performed prone. However, we take care to avoid hyperextension, which can strain the graft. As with the wall pushes, only the operated extremity is strengthened to promote symmetry between the legs. Generally this is begun at the end of the third month or the beginning of the fourth month.

ADDUCTOR/ABDUCTOR STRENGTHENING Hip abductor and adductor strengthening is done with the knees flexed and the quadriceps relaxed to avoid ACL strain, often in the sitting position with elastic tubing. In month 5 it is also done in full extension. Isometric squeezing of a ball placed between the knees is also performed.

THE GASTROCNEMIUS AND TRICEPS SURAE Beynnon’s work has shown that gastrocnemius contraction imparts strain to the ACL with no good way to counteract it. Because the triceps surae is the strongest lever in the body and triceps surae weakness has not been found to be a significant rehabilitative problem after ACLR, we avoid gastrocnemius exercises (e.g., toe raises) until the fourth postoperative month. Furthermore, we have found that specific isolated triceps surae exercises can result in Achilles tendonitis. We therefore usually rely more on cycling, elliptical training, and running to rehabilitate this muscle group.

STAIRS We encourage patients to step up with the normal leg and down with the affected leg during the first 3 postoperative months. Again, Beynnon’s research has shown stairs to impart significant ACL strain.

LOWER EXTREMITY CYCLICAL LOADING Cycling, Running, and Elliptical Training

FIG. 66-2 The 90-degree wall push using a scale as a dynamometer is a valuable home quadriceps exercise.

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There is no lower extremity cyclical loading exercise that does not strain the ACL. Graft abrasion can also occur before full tunnel healing has occurred. We therefore view this as the highest-risk part of the rehabilitation protocol and delay it until the fourth postoperative month, when all fixation points should be well healed. Grafts are still weak and still remodeling at this time but should be much better able to withstand strain and tunnel abrasion than in the

The Stability-Conservative Anterior Cruciate Ligament Reconstruction Rehabilitation Protocol

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HAMSTRING VERSUS BONE–PATELLAR TENDON–BONE

FIG. 66-3 The elliptical trainer provides excellent cardiovascular and balanced muscular training.

earlier postoperative period. We begin with elliptical training (Fig. 66-3) and cycling in month 4. We allow running in month 5. We delay the onset of running because it is more likely than cycling and elliptical training to cause patellofemoral symptoms. If tendonitis or patellar symptoms start, we stop these exercises for a week or two and begin again. Freestyle swimming can also be started at this time.

GAIT TRAINING We keep patients non–weight bearing for 3 days in a brace with range of motion (ROM) of 20 to 120 degrees. The brace elevates the affected leg during gait, avoiding hamstring fatigue. We keep patients non–weight bearing during this time for their comfort. On the third or fourth postoperative day, the brace is changed to 0 degrees of extension and full flexion. At this time patients may continue wearing it or discard it, as they prefer. Physical therapy is started for ROM and also gait training. Gait training has two requirements: “no pain and no limp.” To achieve this, the typical patient will use two crutches for 2 to 3 weeks partial weight bearing, then one crutch for 1 to 2 weeks. As they progress, patients will continue to use more walking assistance for longer distances walked. We stress that they should have a perfect gait without any limp or pain before progressing from two to one to no crutches. The goal is to develop smooth mid-stance knee flexion without pain and inflammation. We counsel patients that they should be in no hurry to discard their crutches.

PROPRIOCEPTION The value of proprioceptive exercise is controversial, but we begin them also in month 4 to allow healing of neural elements.

Our experience with this protocol is limited to the use of HS grafts because we do not perform patellar tendon grafts. It is possible that it is less suited for BPTB grafts due to their greater tendency toward stiffness and quadriceps atrophy. Also, the more rapid healing of the bone plug in the tunnel may decrease the risk of some of the features of the accelerated program. Even if the accelerated program were to decrease BPTB stability, it might be justified to avoid greater problems with motion and atrophy. We think that studies comparing somewhat less accelerated protocols after BPTB would be useful in this regard. We would also suggest that those using the accelerated program review Dr. Shelbourne’s excellent chapter reviewing it in this text (see Chapter 65). We believe the protections he provides, especially in the first postoperative week, are not clearly known to many and bear reviewing.

ALLOGRAFT REHABILITATION Allografts are associated with lower stability rates (see Chapter 69) and delayed recellularization (see Chapter 55). For this reason we believe it is prudent to progress at a slightly slower rate with allografts. We have no supporting data, but we begin cyclical loading after 4 months instead of 3 and allow full activities at 9 months instead of 6.

HOME VERSUS CLINIC THERAPY In the first phase of therapy, when motion is being restored, patients come to the clinic three times per week. We teach patients how to perform their exercises at home and taper the clinic visits quickly depending on the patient. This is more convenient for the patient and helps conserve scarce healthcare resources. Similarly, during strengthening many patients attend only once per week.

EQUIPMENT We do not use isokinetic strengthening equipment. We believe that nonisokinetic resistive equipment provides a more natural workout, particularly eccentrically. We use a leg table for prone leg curls, a total gym for the quadriceps, and exercise tubing. We use an elliptical trainer, a stationary bike, and a NordicTrack cross-country ski machine for aerobic conditioning. 525

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STRENGTH TESTING We strength test all patients by first testing their nonaffected leg. Resistance is set so that they can accomplish between 10 and 25 repetitions of the given exercise. A clock or metronome is used to control rate. A goniometer is used to specify ROM. Their number of repetitions is recorded. For example, for the leg curl a patient may be able to perform 20 prone leg curls from 5 to 90 degrees with 15 pounds of weight with the normal leg. The patient would then be tested on the reconstructed extremity using the same parameters. If the patient can perform 10 repetitions, the therapist would report this as 50% hamstring strength or power because, in this example, they performed 20 with the opposite extremity. We strength test every 2 to 4 weeks. Many patients from out of town perform rehabilitation on their own and come in only for monthly or bimonthly physician visits. Prior to this visit our therapist sees the patient and performs a strength test, the results of which are then reported to me at the visit. Hamstrings, quadriceps, adductors, and abductors are tested in this fashion. Patients are followed until they have achieved at least 95% strength. The overwhelming majority of patients achieve this level by the time of their release to full unrestricted activities at 6 months, and many exceed 100%.

RESULTS This protocol has been associated with a 0% rate of graft failure20 in both primary and revision ACLRs with no significant permanent motion problems. Complete restoration of strength by 6 months postoperatively has been routinely obtained. Patients lose strength early postoperatively but generally have little difficulty getting it back. The only exceptions to this have been a small number of patients with patellar degeneration, in whom intensive quadriceps loading is avoided to avoid exacerbation of their symptoms.

SUMMARY OF PROTOCOL Phase I: Restoration of Motion (brace use optional): Timing: Begins postoperative day 3 until goals met, usually by end of second postoperative week. Range of motion: Exclusively passive ROM activities by physical therapist, supplemented by patient’s family or friends. Goal: 0 to 115–120 degrees ROM. Hyperextension and flexion beyond 120 degrees are specifically prohibited.

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Gait training: Weight bearing as tolerated gait with two crutches progressing to one and then no crutches. Goal: Pain- and limp-free gait to allow progression from two to one to no crutches. Phase II: Restoration of Strength—Affected Leg Only Timing: Begins postoperative week 3 for quadriceps wall push exercise, postoperative month 4 for other muscle groups, until goals met. We will sometimes begin the nonquadriceps muscle group strengthening earlier for high-performance athletes. Hamstrings: Prone leg curls and other exercises, avoiding hyperextension. Quadriceps: Wall pushes (isometric supine at 90 degrees) progressing to short arc, 60 to 90 degrees isotonic, in postoperative month 4 (see Phase III). Abductors/Adductors: Performed sitting with knees flexed. Goal: Symmetrical strength. Strength tests are performed every 2 to 4 weeks. Phase III: Aerobic and Quadriceps Intensive Phase Timing: Postoperative month 4 until goals met. Elliptical/stationary bicycle/freestyle swimming: Two to three times weekly, not to exceed 20 minutes, at beginning of month 4. Running: Begins fifth postoperative month if desired by patient, two to three times weekly. Quadriceps strengthening: 60- to 90-degree arc begun in month 4. Full-arc quadriceps allowed in month 5. Goal: Aerobic fitness, full restoration of quadriceps strength. Phase IV: Unrestricted Activities Timing: 6 months postoperative, if strength is at least 80% of opposite extremity. Pivoting: Pivoting/jumping and all other activities allowed without restriction and without bracing.

References 1. Blickenstaff KR, Grana WA, Egle D. Analysis of a semitendinosus autograft in a rabbit model. Am J Sports Med 1997;25:554–559. 2. Milano G, Mulas PD, Sanna-Passino E, et al. Evaluation of bone plug and soft tissue anterior cruciate ligament graft fixation over time using transverse femoral fixation in a sheep model. Arthroscopy 2005;21:532–539.

The Stability-Conservative Anterior Cruciate Ligament Reconstruction Rehabilitation Protocol 3. Weiler A, Peters G, Maurer J, et al. Biomechanical properties and vascularity of an anterior cruciate ligament graft can be predicted by contrast-enhanced magnetic resonance imaging. Am J Sports Med 2001;29:751–761. 4. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel: a biomechanical and histological study in the dog. J Bone Joint Surg 1993;75A:1795–1803. 5. Beynnon BD, Fleming BC, Johnson RJ, et al. Anterior cruciate ligament strain behavior during rehabilitation exercises in vivo. Am J Sports Med 1995;23:24–34. 6. Beynnon BD, Howe JG, Pope MH, et al. The measurement of anterior cruciate ligament strain in vivo. Int Orthop 1992;16:1–12. 7. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292–299. 8. Fleming BC, Beynnon BD, Renstrom PA, et al. The strain behavior of the anterior cruciate ligament during bicycling: an in vivo study. Am J Sports Med 1998;26:109–118. 9. Markolf KL, O’Neill G, Jackson SR. Effects of applied quadriceps and hamstrings muscle loads on forces in the anterior and posterior cruciate ligaments. Am J Sports Med 2004;32:1144–1149. 10. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 11. DeAndrade JR, Grant C, Dixon AS. Joint distension and reflex muscle inhibition in the knee. J Bone Joint Surg 1966;47A:313–322. 12. Fahrer H, Rentsch HU, Gerber NJ, et al. Knee effusion and reflex inhibition of the quadriceps. J Bone Joint Surg 1988;70B:635–638. 13. Jones DW, Jones DA, Newham DJ. Chronic knee effusion and aspiration: the effect on quadriceps inhibition. Br J Rheumat 1987;26:370–374.

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14. Konishi Y, Suzuki Y, Hirose N, et al. Effects of lidocaine into knee on QF strength and EMG in patients with ACL lesion. Med Sci Sports Exerc 2003;35:1805–1808. 15. Konishi Y, Fukubayashi T, Takeshita D. Possible mechanism of quadriceps femoris weakness in patients with ruptured anterior cruciate ligament. Med Sci Sports Exerc 2002;34:1414–1418. 16. Morrissey MC. Reflex inhibition of thigh muscles in knee injury: causes and treatment. Sports Med 1989;7:263–276. 17. Stokes M, Young A. The contribution of reflex inhibition to arthrogenous muscle weakness. Clin Sci 1984;67:7–14. 18. Coleridge SD, Amis AA. A comparison of five tibial-fixation systems in hamstring-graft anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:391–397. 19. Kousa P, Jarvinen TLN, Vihavainen M, et al. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part II: tibial site. Am J Sports Med 2003;31:182–188. 20. Giurea M, Zorilla P, Amis AA, et al. Comparative pull-out and cyclic-loading strength tests of anchorage of hamstring tendon grafts in anterior cruciate ligament reconstruction. Am J Sports Med 1999;27:621–625. 21. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 22. Renstrom P, Arms SW, Stanwyck TS, et al. Strain within the anterior cruciate ligament during hamstring and quadriceps activity. Am J Sports Med 1986;14:83–87. 23. Durselen L, Claes L, Kiefer H. The influence of muscle forces and external loads on cruciate ligament strain. Am J Sports Med 1995;23:129–136.

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67 CHAPTER

Andrew Riff Mark D. Miller

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Hamstring Regeneration Following Harvest for Anterior Cruciate Ligament Reconstruction: A Review of the Current Literature Anterior cruciate ligament (ACL) reconstruction is one of the most prevalent orthopaedic procedures, with more than 100,000 performed annually.1 The majority of these operations use autograft donor tissue, with hamstring tendons (either semitendinosus [ST] or semitendinosus with gracilis [ST/Gr]) recently gaining approval in relation to the traditionally favored bone– patellar tendon–bone (BPTB) graft. Historically, the BPTB graft has been advocated for a number of reasons, including its well-described regrowth phenomenon, which involves the reconstitution of its central third following harvest. However, supporters of hamstring grafts cite potential patellofemoral pain, patellar tendonitis, tendon rupture, and patellar fracture as possible disadvantages of BPTB use.2–5 In 1992, Cross et al reported the regeneration of the hamstring tendons following harvest, a notion that has been supported with increasing evidence in the literature.6 Overall, as a result of this regeneration of the harvested tendon, hamstring strength has been found to reach near-normal levels 1 year postoperatively. This regeneration is termed the lizard tail phenomenon. The validation of such a phenomenon may offer an additional advantage for the use of hamstrings in ACL reconstruction. This chapter will review and summarize the literature to date examining the morphological and functional regeneration of harvested ST/Gr tendons from a radiographic, functional, and histological standpoint. It must be noted that relevant studies are somewhat difficult to compare due to unavoidable differences in followup, rehabilitation protocol, and testing methods

found in the literature. Additionally, some studies confer results following ST/Gr harvest, whereas others evaluate those involving only ST harvest.

RADIOGRAPHIC STUDIES A number of studies have attempted to describe the morphological aspect of regeneration using the radiographic images of the ST and Gr tendons following harvest. These studies have provided information concerning the extent of regeneration, the location of the regenerate tissue, and the presence or absence of muscle atrophy. In the study conducted by Cross noted previously, magnetic resonance imaging (MRI) evaluation of four patients (6 months postoperatively) displayed tendonlike tissue extending from the hamstring muscle bellies to the medial gastrocnemius (Fig. 67-1).6 In this case, insertion appeared to be diffused into the medial popliteal fascia, but electromyographic examination revealed normal muscle activity and innervation patterns in the hamstring. Simonian et al similarly reported proximal insertion of the regenerate ST tendon.7 In contrast with common trends in the literature, however, no compensatory hypertrophy of the biceps femoris, semimembranosus (SM), or sartorius was appreciable when compared with the unaffected side. A number of papers by Eriksson et al have reported MRI imaging of regenerate hamstring following harvest of the ST tendon. In the first (1999), they reported ST regeneration to the

Hamstring Regeneration Following Harvest for Anterior Cruciate Ligament Reconstruction: A Review of the Current Literature

FIG. 67-1 This T1-weighted sagittal magnetic resonance image of the knee shows a “thickened band of tissue” where the hamstring tendon has regenerated.

level of the proximal tibia in 8 of 11 patients evaluated 6 to 12 months postoperatively, whereas in the other three patients the remnant ST fused with the SM tendon proximal to the joint line.8 Those patients with regenerate distal ST demonstrated fusion of the ST and Gr approximately 30 mm distal to the joint line with insertion as a conjoint tendon on the pes anserinus. The authors suggested that the precise level of union is insignificant as long as it is distal to the joint line. The proximal cross-sectional area of the ST also differed between groups. This measure averaged 91% of the contralateral tendon in those with distal regeneration and 79% in those without distal regeneration. In a second study (2001), Eriksson et al evaluated six patients who ranged from 7 to 28 months following ACL reconstruction, using only the ST graft.9 MRI imaging displayed regeneration of ST tissue in five of the six patients to the pes insertion site, averaging approximately 30 mm distal to the joint line. The sixth patient had no evidence of a new tendon 24 months after surgery. Concurrently in 2001, Eriksson and Hamberg published another study in which patients underwent MRI between 6 and 12 months after ST harvest.7 In this case, 12 of the 16 patients displayed radiological evidence of ST regeneration in which the new tendon fused with the (nonharvested) Gr 10 to 30 mm below the joint line and inserted on the pes as a conjoined tendon. Although some ST atrophy was notable in all patients, significantly more was appreciable in patients without tendon regeneration. In those patients without regeneration, however, compensatory SM hypertrophy was more extensive. Rispoli et al performed their study in a different manner, attempting to provide radiographic documentation

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of tendon regeneration in 21 patients at distinct time intervals ranging from 2 weeks to 32 months following ACL surgery using ST/Gr.5 However, they did not sequentially image any individuals. At the points shortly following surgery, fluid and edema in the tendon tracts were noted, and tendonlike tissue reached the superior patellar pole 6 weeks after surgery. Presence of the tendons below the joint line arose at variable intervals, arising anywhere from 3 to 12 months postoperatively. Papandrea et al also observed similar linear development in a study using sequential ultrasounds of 40 patients at 2 weeks, and 1, 2, 3, 6, 18, and 24 months after surgery using ST/Gr.10 This study documented a course of maturation proceeding from ill-defined hypoechogenic tissue early on to hamstring hypertrophy in the first year, before a distinct, well-defined tendon signal developed between 18 and 24 months. This study noted a more proximal insertion into the medial popliteal fascia than normal. This process has been further documented by multiple other studies as recently as 2004. Nakamura et al used MRI and three-dimensional computed tomography (3D-CT) scans in a retrospective study assessing ST regeneration in eight patients, each a minimum of 2 years postoperative.11 In five of eight patients, distinct tendonlike tissue was observed running along the same course as the native hamstrings, the most notable difference being distal attachment to the medial popliteal fascia. In the remaining three subjects, the residual ST fused proximally into the SM muscle belly. The study apparently observed similar regeneration of the Gr, but an explicit description was not included. Tadokoro et al also imaged 28 patients with MRI at a minimum of 2 years following ACL reconstruction with ST/Gr.12 This study reported regeneration of 22 of 28 ST tendons and 13 of 28 Gr tendons, with no differences in cross-sectional area between surgical and contralateral knees. More importantly, they found that there was no correlation between morphological regeneration and peak flexion strength in high degrees of flexion (90 and 110 degrees) in both prone and supine positions despite less strength in affected limbs. Williams et al also performed MRI on eight patients both preoperatively and at the point of return to sports (an average of 6 months after reconstruction using ST/Gr).13 Seven of the eight patients exhibited regenerate tendons; however, the majority of the tendons had not yet inserted on the tibia at the point of imaging. Overall volume of the ST and Gr muscles diminished by an average of 30%, and in contrast with Tadokoro’s study, this extent appeared to correlate well with the extent of tendon regeneration. Additionally, much like Eriksson’s study, compensatory hypertrophy of the SM and biceps femoris muscles was noted. Nakamae et al also used 3D-CT to gain a better sense of the full-length morphology of the regenerate tissue by imaging 29 patients at various time points.14 A 3D-CT 529

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FIG. 67-2 Gross morphology of regenerate (R) and native (N) rabbit hamstring tendons. Compared with the native tendon, the regenerate tendon is highly variable in size and was found to attach to the tibia at variable locations.

examination was performed in all patients preoperatively, 24 patients at 1 month, 8 patients at 3 months, 21 patients at 6 months, and 20 patients at 12 months postoperatively following ST harvest only. Although no patients had evidence of regeneration at 1 month after surgery, a regenerate tendon was detected in all but two patients at 12 months after surgery, with the regenerate tissue coursing as expected from the muscle bellies to the normal insertion site on the proximal tibia. Although there is a perception that regeneration occurs almost universally, it is not an entirely predictable phenomenon. For reasons not fully understood, a small percentage of patients in a number of studies lack regenerate tendons. Notably, two studies by Eriksson and one by Hioki et al report 17%, 18%, and 45% of patients with failed regrowth, respectively.3,9,15,16 Additionally, among the population with evidence of regrown tissue, the regenerate tendon frequently ranges in size and diverges from the expected insertion site, inserting proximally and medially to the pes anserinus (Fig. 67-2). This varied insertion could have important biomechanical consequences that explain varied strength of knee flexion and internal rotation. A more proximal insertion shortens the tendon’s moment arm, inhibiting the muscle’s ability to flex the knee. Additionally, in the case of documented insertion on the medial popliteal fascia, a more lateral insertion hinders the hamstring muscles from generating internal torque and resisting external rotation of the tibia.

FUNCTIONAL STUDIES Numerous studies have also examined hamstring strength following tendon harvest. Postoperative leg strength has been 530

a concern since at least 1982, when Lipscomb et al published a retrospective evaluation of 482 cases involving either ST or ST/Gr harvest.17 Impressively, none of the subjects in this study displayed significant loss of knee flexion strength at an average of 26 months postoperatively. Specifically, hamstring strength averaged 99% of the normal knee when ST/Gr was used and 102% when the Gr was not harvested. More widespread interest in the subject of strength regeneration peaked in the early 1990s, aroused by two noteworthy studies. The aforementioned four-patient study by Cross et al demonstrated minimal decreases (averaging less than 10%) in peak flexion and extension strength in three of the four patients, whereas the fourth patient actually displayed improved strength measurements.6 Concurrently, Marder et al published contradictory results in a study comparing hamstring strength between patients with ipsilateral ST/Gr grafts and BPTB grafts.18 In the group who underwent ST/Gr graft harvest, the study noted a 17% decrease in isokinetic knee flexion strength. Eriksson et al similarly documented vast strength deficiencies relative to the unaffected leg in the peak torque of hamstrings (–25%) and quadriceps (–50%) during both concentric and eccentric testing in 16 patients ranging between 8 and 18 months after surgery.3 This comprehensive, overwhelming weakness may indicate inadequate postoperative rehabilitation. Details of the postoperative protocol were not provided. Despite these inconsistent findings, more recent studies examining knee flexion strength have generally documented minimal or no deficits in peak torque following both ST and ST/Gr harvest.19,20 Yasuda et al demonstrated this most favorably in their prospective examination of peak torque after ST/Gr harvest from either the ipsilateral or contralateral leg.21 Neither circumstance exhibited significant decrease in flexion strength after the immediate postoperative period was surpassed. More detailed examinations, however, have found slight divergence in torque assessment. A study conducted by Adachi et al evaluated 58 patients with regard to peak torque, peak torque angle, and total work at an average of 2 years after ACL reconstruction using ST, ST/Gr, or allograft tissue.2 Much like their counterparts, they found very little difference in peak strength or total work between groups; however, the autograft groups exhibited peak torque at a significantly shallower angle than in the allograft group. Ohkoshi et al likewise noted no difference in peak torque flexion and quantified the significant decrease in peak torque angle at about 11 to 15 degrees after evaluating 25 patients following ST harvest.22 The study theorized that this decrease in peak torque angles is attributable to compensation by flexor muscles that have peak torque at a shallower angle than the hamstrings. Irie and Tomatsu used cybex testing to assess the flexor strength of

Hamstring Regeneration Following Harvest for Anterior Cruciate Ligament Reconstruction: A Review of the Current Literature 13 patients at 12 to 16 months after ST/Gr or Gr harvest.23 Such testing yielded no difference in maximum torque but demonstrated a 25% deficiency in total work possible at angles of flexion greater than 75 degrees. In a more recent study, Nakamura et al evaluated 74 consecutive patients 2 years after ST or ST/Gr surgery and found that peak torque flexion was greater than 90% of that in the unaffected knee.24 Consistent with other studies, peak torque at 90 degrees was again deficient in the ST and ST/Gr groups alike. In one of the only prospective randomized analyses of the subject, Tashiro et al randomly assigned 90 patients to ACL reconstruction with either ipsilateral ST or ST/Gr autograft.25 The authors examined peak flexion torque at 6, 12, and 18 months, finding that the ST and ST/Gr groups did not differ significantly from one another and that torque was only diminished at the 6-month point, after which it returned to preoperative levels. This study also noted significantly less recovery at high angles in both groups, with hamstring strength decreases of up to 30% at angles greater than 70 degrees. In the CT imaging study by Nakamae et al described previously, isokinetic measurements at 60 degrees of knee flexion demonstrated a strength deficiency in which peak torque was an average of 68% of the control side at 6 months and increased to 83% by 12 months.14 All in all, the studies universally demonstrate that deficits in postoperative knee strength, especially in flexion, are minimal in cases of both ST and ST/Gr tendon harvest. The only exception to this conclusion is somewhat diminished strength at high angles of flexion. Due to the limits of strength testing, it cannot be discerned whether the maintenance of flexion strength is a result of hamstring regeneration or the compensatory hypertrophy of other hamstring muscle– tendon units. A few recent studies suggest that internal tibial rotation torque may be a better indication of the extent of regeneration than pure flexion strength. Viola et al found that among 23 patients who had undergone ACL reconstruction with ST/Gr, internal tibial rotation torque was approximately 10% to 15% of the contralateral limb at an average of 51 months postoperatively (observed at all velocities; 60, 120, and 180 degrees/sec).26 Similarly, Armour et al discovered internal rotation deficits in the operated leg measuring between 12% and 15% at a 2-year minimum follow-up.27 This study more specifically targeted the knee joint by limiting motion at the ankle joint during strength testing. Segawa et al also observed comparable results in assessing internal tibial torque in 32 patients with ST grafts and 30 patients with ST/Gr grafts at 1 year postoperative.28 Internal rotation strength was again considerably less than the contralateral leg. The diminished internal rotation strength was more markedly present when the Gr was also harvested, leading the authors to recommend harvest of only the ST whenever

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possible. Additionally, on account of the overwhelming decrease in strength, the authors encourage a rehabilitation protocol with exercises specifically focused on improving internal rotation strength. Nevertheless, studies have yet to correlate deficiencies in either knee flexion strength or internal rotation strength with functional shortcomings or impaired athletic performance.

HISTOLOGICAL STUDIES It has long been theorized that neotendons observed on MRI were merely scar tissue. Although radiographic and functional studies have demonstrated conclusively that harvested hamstring tendons regenerate in the same orientation and with the same strength as native tendons, only recently have surgeons performed histological or biomechanical studies to assess the quality of the regenerate tissue. In the Eriksson and Hamberg study assessing MR images of regenerate tissue, biopsies of hamstring muscle tissue preoperatively and postoperatively were also evaluated.3 Evaluation revealed that the cross-sectional area of the muscle fibers trended toward small values in regenerate tissue; however, the fiber composition and citrate synthetase activity remained consistent with native tissue (Fig. 67-3). In another study of the same group, Eriksson at al examined and compared the peripheries of five regenerate ST tendons with normal tendons.9 In this case, the regenerate collagen fibers held the same alignment and breadth as the control tendons and exhibited uniform staining, with the exception of the appropriate forms of collagen. There were also appreciable small areas of irregularity in collagen orientation and increased fibroblast and capillary formation, indicating the presence of scar-like tissue. Likewise, Ferretti performed histological analysis of regenerate tissue from three patients at 6, 24, and 27 months after surgery at the time of routine hardware removal.29 At the histological level, the neotendon is initially (at 6 months) a fibrous structure with fibroblastic proliferation and capillaries but few collagen fibers. However, over time (at the latter two time points) the neotendon acquires qualities consistent with a healthy tendon demonstrating thicker, longitudinally oriented fibers. However, small focal regions of scar tissue and irregular collagen orientation often persist long after harvest. This compositional inconsistency may alter biomechanical properties of the reconstituted tendon.

ANIMAL MODELS Animal models of tendon regeneration are quite useful in offering trends in regeneration for a large data source. Two studies by Miller et al used MRI as well as 531

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R

N

100 Native

90

Regenerate Poly. (Native) Poly. (Regenerate)

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70 60 50 40 30 20 10 0 14

28

42

56

70

84

98

112

126

140

154

168

182

196

210

224

266

Tendon fibril diameter (nm) FIG. 67-3 Electron microscopy of 500 fibrils counted at 76,000 magnification and distribution of collagen fibril diameters from native (N) and regenerate (R) rabbit hamstring tendons at 28 weeks after harvest. The average diameter of the collagen fibrils in the regenerate tendon is significantly smaller than that of the native tendon.

histological and biomechanical evaluation of New Zealand white rabbits to evaluate tendon regeneration. In the first study, each of 10 rabbits demonstrated radiologic evidence of some regenerate tissue at 16 or 28 weeks.30 MRI indicated a process from wavy regenerate tissue stopping short of the tibia at 16 weeks, becoming taut and inserting on the ST insertion site by 28 weeks. This course of maturation was mirrored in histological examination. Microscopic examination at 16 weeks displayed wavy collagen fibers turning into healthy tendinous fibers by 28 weeks. The tendons also appeared to strengthen with maturation as indicated by tensile biomechanical testing (Fig. 67-4). However, at both time points the regenerate tissue withheld significantly less maximum load to failure than native tissue (by 77% at 16 weeks and 48% at 28 weeks).

532

FIG. 67-4 Tendon undergoing biomechanical tensile strength testing to assess tissue strength.

Hamstring Regeneration Following Harvest for Anterior Cruciate Ligament Reconstruction: A Review of the Current Literature A more comprehensive analysis of regenerate rabbit tendons was reported in a follow-up study conducted by Miller and Gill et al.31 In follow-up, ST tendons appeared to regenerate at 9 to 12 months after harvest in 26 of 31 of the rabbits evaluated. However, the neotendon was highly variable in size and tibial insertion site. The tissue resembled native tendon in cellularity and immunolocalization of type I collagen, fibril size was markedly smaller, fibril orientation was more irregular, and regenerate tendon composition contained significantly lower levels of proteoglycan than native tissue. Detailed biomechanical examination in the same study demonstrated significantly lower maximum loads to failure and structural stiffness (approximately 25% of control tendons) in regenerate tissue. The regenerate tendons’ inferior biomechanical qualities strongly suggest inferior material properties of the tissue. However, because measures were not precisely taken, it may also be at least partly attributable to smaller cross-sectional areas of the regenerate tissue.

FUTURE DIRECTIONS The precise mechanism of regeneration and the desirable qualities for strong biomechanical performance are not well understood. It is hypothesized that the regeneration process likely begins at the more proximal vascular areas and extends distally as extrasynovial hematoma collects along fascial planes and acts as a scaffold for fibroblast precursor cells. Carofino et al notes, however, that the fascial planes could not possibly constrict a regenerate tendon to dimensions and shape similar to the original because the medial knee does not form a well-defined tubular structure necessary for precise reconstitution.15 Despite the primitive state of our knowledge, surgeons have begun to propose the use of regenerate tendon for revision surgeries. Yoshiya et al describe the reharvesting of hamstrings for revision ACL reconstruction, 8 months following the index reconstruction in a 2004 case study.32 At the time of surgery, Yoshiya obtained a biopsy of the regenerate tissue that displayed significant smaller diameter of collagen fibrils compared with normal tendons. Although it is premature to make an overarching assessment, the patient was reportedly doing well at 6 months postoperatively. The authors appropriately note that it is too early to make a determination on the viability of regenerate grafting on a routine basis.

CONCLUSIONS The current literature has overwhelmingly established that despite a small subset of the patient population having an

67

unexplainable lack of regrowth, the ST and Gr tendons regenerate to some degree in the vast majority of patients. Additionally, nearly all subjects, including those without full regeneration, recover preoperative levels of flexion strength with minimal functional deficit. This recovery is a consequence of simultaneous regeneration of the ST and Gr tendons and compensatory hypertrophy of the SM and biceps femoris muscles. In any given patient, however, the extent of tissue regeneration and reinsertion site for the neotendon are unpredictable. The new tissue has been shown to insert on the popliteal fascia and medial gastrocnemius in addition to the pes anserinus. The quality of the regenerate tissue has been shown to be histologically inferior as well. Although the new tissue has collagenous properties, it is less ordered and performs poorly in biomechanical testing relative to normal tendons. The intrinsic low morbidity of hamstring harvest coupled with increasing documentation of tendon regeneration makes ST and ST/Gr grafts increasingly popular options for ACL reconstruction. Future studies will be necessary to verify natural and controllable factors that improve the likelihood of anatomical regeneration and the feasibility of reharvesting regenerate tissue for revision ACL reconstruction.

References 1. Battaglia TC, Miller MD. Strength and regrowth of hamstring tendons after hamstring autograft anterior cruciate ligament reconstruction. Tech Orthop 2005;20:1–5. 2. Adachi N, Ochi M, Uchio Y, et al. Harvesting hamstring tendons for ACL reconstruction influences postoperative hamstring muscle performance. Arch Orthop Trauma Surg 2003;123:460–465. 3. Eriksson K, Hamberg P, Jansson E, et al. Semitendinosus muscle in anterior cruciate ligament surgery: morphology and function. Arthroscopy 2001;17:808–817. 4. Graham SM, Parker RD. Anterior cruciate ligament reconstruction using hamstring tendon grafts. Clin Orthop 2002;402:64–75. 5. Rispoli DM, Sanders TG, Miller MD, et al. Magnetic resonance imaging at different time periods following hamstring harvest for anterior cruciate ligament reconstruction. Arthroscopy 2001;17:2–8. 6. Cross MJ, Roger G, Kujawa P, et al. Regeneration of the semitendinosus and gracilis tendons following their transection for repair of the anterior cruciate ligament. Am J Sports Med 1992;20:221–223. 7. Simonian PT, Harrison SD, Cooley VJ, et al. Assessment of morbidity of semitendinosus and gracilis tendon harvest for ACL reconstruction. Am J Knee Surg 1997;10:54–59. 8. Eriksson K, Larsson H, Wredmark T, et al. Semitendinosus tendon regeneration after harvesting for ACL reconstruction. A prospective MRI study. Knee Surg Sports Traumatol Arthrosc 1999;7:220–225. 9. Eriksson K, Kindblom LG, Hamberg P, et al. The semitendinosus tendon regenerates after resection: a morphologic and MRI analysis in 6 patients after resection for anterior cruciate ligament reconstruction. Acta Orthop Scand 2001;72:379–384. 10. Papandrea P, Vulpiani MC, Ferretti A, et al. Regeneration of the semitendinosus tendon harvested for anterior cruciate ligament reconstruction. Evaluation using ultrasonography. Am J Sports Med 2000;28:556–561. 11. Nakamura E, Mizuta H, Kadota M, et al. Three-dimensional computed tomography evaluation of semitendinosus harvest after anterior cruciate ligament reconstruction. Arthroscopy 2002;20:360–365.

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Anterior Cruciate Ligament Reconstruction 12. Tadokoro K, Matsui N, Yagi M, et al. Evaluation of hamstring strength and tendon regrowth after harvesting for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:1644–1649. 13. Williams GN, Snyder-Mackler L, Barrance PJ, et al. Muscle and tendon morphology after reconstruction of the anterior cruciate ligament with autologous semitendinosus-gracilis graft. J Bone Joint Surg 2005;86A:1936–1946. 14. Nakamae A, Deie M, Yasumoto M, et al. Three-dimensional computed tomography imaging evidence of regeneration of the semitendinosus tendon. J Comput Assist Tomogr 2005;29:241–245. 15. Carafino B, Fulkerson J. Medial hamstring tendon regeneration following harvest for anterior cruciate ligament reconstruction: fact, myth, and clinical implication. Arthroscopy 2005;21:1257–1264. 16. Hioki S, Fukubayashi T, Ikeda K, et al. Effect of harvesting the hamstring tendon for anterior cruciate ligament reconstruction on the morphology and movement of the hamstring muscle: a novel MRI technique. Knee Surg Sports Traumatol Arthrosc 2003;11:223–227. 17. Lipscomb AB, Johnston RK, Snyder RB, et al. Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament. Am J Sports Med 1982;10:340–342. 18. Marder RA, Raskind JR, Carroll M. Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction. Patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478–484. 19. Maeda A, Shino K, Horibe S, et al. Anterior cruciate ligament reconstruction with the multistranded autogenous semitendinosus tendon. Am J Sports Med 1991;19:478–484. 20. Marcacci M, Zaffagnini S, Ianoco F, et al. Arthroscopic intra- and extra-articular anterior cruciate ligament reconstruction with gracilis and semitendinosus tendons. Knee Surg Sports Traumatol Arthrosc 1998;6:68–75. 21. Yasuda K, Tsujino J, Ohkoshi Y, et al. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med 1995;23:706–716. 22. Ohkoshi Y, Inoue C, Yamane S, et al. Changes in muscle strength properties caused by harvesting of autogenous semitendinosus tendon for reconstruction of contralateral anterior cruciate ligament. Arthroscopy 1998;14:580–584.

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23. Irie K, Tomatsu T. Atrophy of semitendinosus and gracilis and flexor mechanism function after hamstring tendon harvest for anterior cruciate ligament reconstruction. Orthopedics 2002;25:491–495. 24. Nakamura N, Horibe S, Sasaki S, et al. Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons. Arthroscopy 2002;18:598–602. 25. Tashiro T, Kurosawa H, Kawakami A, et al. Influence of medial hamstring tendon harvest on knee flexor strength after anterior cruciate ligament reconstruction: a detailed evaluation with comparison of single- and double-tendon harvest. Am J Sports Med 2003;31:522–529. 26. Viola RW, Sterett WI, Newfield D, et al. Internal and external tibial rotation strength after anterior cruciate ligament reconstruction using ipsilateral semitendinosus and gracilis tendon autografts. Am J Sports Med 2000;28:552–555. 27. Armour T, Forwell L, Litchfield R, et al. Isokinetic evaluation of internal/external tibial rotation strength after the use of hamstring tendons for anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:1639–1653. 28. Segawa H, Omori G, Koga Y, et al. Rotational muscle strength of the limb after anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon. Arthroscopy 2002;18:177–182. 29. Ferretti A, Conteduca F, Morelli F, et al. Regeneration of the semitendinosus tendon after its use in anterior cruciate ligament reconstruction: a histologic study of three cases. Am J Sports Med 2002;30:204–207. 30. Leis HT, Sanders TG, Larsen KM, et al. Hamstring regrowth following harvesting for anterior cruciate ligament reconstruction: the lizard tail phenomenon. Am J Knee Surg 2003;16:159–164. 31. Gill SS, Turner MA, Battaglia TC, et al. Regeneration of the semitendinosus tendon after its use in anterior cruciate ligament reconstruction: a histologic study of three cases. Am J Sports Med 2002;30:204–207. 32. Yoshiya S, Matsui N, Matsumoto A, et al. Revision anterior cruciate ligament reconstruction using the regenerated semitendinosus tendon: analysis of ultrastructure of the regenerated tendon. Arthroscopy 2004;28:532–535.

Suggested Reading Brown CH Jr, Carson EW. The use of hamstring tendons for anterior cruciate ligament reconstruction. Clin Sports Med 1993;12:723–756.

Proprioception and Anterior Cruciate Ligament Reconstruction Many modern rehabilitation programs for patients who have undergone anterior cruciate ligament (ACL) reconstruction incorporate exercises and drills that are directed toward improving neuromuscular function and coordination. They are often loosely referred to as proprioceptive training exercises. This chapter explores the basis for the incorporation of such exercises into rehabilitation following ACL reconstruction. The human ACL has been shown to contain mechanoreceptors including Golgi tendon organs, Pacinian corpuscles, and Ruffini nerve endings.1,2 These receptors contribute to proprioception about the knee joint and are also believed to form part of a reflex arc in which an anterior displacement of the tibia results in hamstring muscle contraction. Such a reflex presumably serves to protect the knee, and the ACL in particular, from such stresses. ACL rupture can therefore be expected to result in disruption or alterations of these pathways. The term proprioception has proved difficult to define succinctly and has similarly been tested and measured by a variety of techniques. The definition of proprioception is generally agreed to include joint position sense and the ability to detect joint movement (kinesthesia). These have been measured by joint position matching tasks and by threshold to detection of passive movement tasks, respectively. Overall, it appears that threshold to detection methods have proved more reliable, although the two types of tests address different aspects of proprioception.

Another approach has been to use tests of neuromuscular function. These involve both afferent and efferent components and therefore test not only proprioception but also the muscular response. Examples of such tests are (1) measurement of latency of hamstring muscle contraction following the application of an anterior displacement force to the tibia and (2) stabilometric tests in which the movement of the center of pressure is measured during a single leg stance. More global functional tests include the various hop tests. When assessing proprioception or neuromuscular function following ACL rupture and subsequent reconstruction, some fundamental issues need to be considered. Because alterations in the uninjured limb have been reported by some authors, it is important to include a group of control subjects. Longitudinal studies are probably of greater benefit than studies using only one point in time, as deficits have been demonstrated to change over time following both injury and reconstructive surgery. The type of graft used is also relevant for tests involving a hamstring muscle response. Using a threshold to detection of passive movement test, Barrack et al3 demonstrated a significantly higher threshold value in ACL deficient limbs compared with the normal contralateral limb in a group of 11 patients tested 3 months following ACL rupture. A group of control subjects showed virtually identical threshold values for both knees. The higher threshold values were attributed to a loss of proprioceptive function. Numerous authors have

68 CHAPTER

Julian A. Feller Kate E. Webster

535

Anterior Cruciate Ligament Reconstruction also described the presence of deficits attributable to loss of proprioception in ACL deficient knees, whereas some authors have shown no differences between injured and contralateral or healthy control subject knees (for review, see Reider et al4). For instance, Pap et al5 found a higher rate of failure to detect passive movement in ACL deficient knees compared with the contralateral knee or healthy control subjects’ knees. However, unlike Barrack et al, they did not find any difference in the threshold to detect passive movement among any of the knees. Beard et al6 measured the latency of reflex hamstring contraction in response to an anteriorly directed shear force to the upper calf in 30 patients with an ACL rupture. They found significantly greater latencies in the ACL deficient knees compared with the contralateral knees. Interestingly, the frequency of giving-way episodes reported by the patients correlated with the latency differential between their two limbs. Many authors have evaluated proprioception following ACL reconstruction, but they have reported conflicting results. This may be due in part to the different methodologies employed. Various tests of proprioception have been used (joint position sense, threshold to detect passive movement, reaction time, and stabilometric testing). ACL reconstructed knees have been compared with either the contralateral knee, healthy control subject knees, or in some instances to both. Most studies have evaluated patients at only one time point, although some have followed patients over time from preoperatively to as long as 3.5 years postoperatively. The results of studies that have either used a control group of subjects or provided longitudinal follow-up have been summarized in Tables 68-1 and 68-2. From Table 68-1 it can be seen that the ACL reconstructed knees have been shown to be either equivalent to or worse than healthy control subject knees. The length of follow-up does not appear to explain the disparate findings. Four of the five studies that found no difference used joint position sense as a measure of proprioception, whereas only two of the five studies that found the ACL reconstructed knees to be inferior used this method of testing proprioception. Two of the longitudinal studies used joint position sense as a measure of proprioception, whereas one used threshold to detect passive movement and another used both joint position sense and threshold to detect passive movement. Iwasa et al7 evaluated joint position sense in 38 subjects before ACL reconstruction using a hamstring tendon graft and every 3 months after surgery to 24 months. There was an improvement in joint position sense from 9 months through 18 months, but there was a small group of eight in whom joint position sense did not improve. A correlation was observed between better stability and better joint position sense. 536

Fremerey et al8 measured joint position sense in 20 patients with chronic ACL deficiency who underwent a patellar tendon ACL reconstruction as well as in 20 control subjects and 20 patients with an acute ACL rupture. Preoperatively the chronic ACL deficient knees had significantly better joint position sense than acute ACL deficient knees but were worse than control subjects’ knees. Following surgery there was an improvement, most of which occurred between 3 and 6 months. There was some further improvement at 3 years, although a small deficit remained in the operated knee for mid-range positions. Reider et al4 undertook a longitudinal study of 26 patients undergoing ACL reconstruction and measured both joint position sense and threshold to detect passive movement preoperatively at 3 and 6 weeks and at 3 and 6 months postoperatively. They used both the contralateral knees as well as the knees of healthy volunteers as controls. The authors concluded that threshold to detect passive movement was a more reliable method than joint position sense for testing proprioception. In the patient group there was no significant difference in the threshold between the injured and contralateral knee at any of the time points. Both knees were significantly worse than the healthy controls preoperatively. However, both knees improved postoperatively such that they were not significantly different than healthy control knees at 6 months postoperatively. The authors noted that improvements in proprioception were seen as early as 6 weeks following ACL reconstruction. Such a short time period is not consistent with reinnervation of the graft being the basis of the improvement. The authors, as well as Iwasa et al,7 suggest that the improvement is probably due to the provision of a static restraint that reduces abnormal afferent activity from the capsule and other ligaments. A number of authors have investigated the role of rehabilitation protocols designed to improve proprioception and neuromuscular function in patents with ACL ruptures (for review, see Cooper at al9). Such protocols have been associated with some limited improvements in joint position sense and hop testing as well as muscle strength and subjective rating when compared with traditional strengthening programs. In a group of 50 patients with ACL deficiency, Beard et al10 compared a muscle-strengthening rehabilitation protocol with a program designed to enhance proprioception and reduce the latency of reflex hamstring contraction. The proprioceptive program was associated with greater improvements in reflex hamstring contraction latency and functional scores compared with the strengthening program. Perhaps as a result of the use of such proprioceptive programs in patients with ACL rupture, proprioceptionrelated exercises are now frequently included in

Proprioception and Anterior Cruciate Ligament Reconstruction

68

TABLE 68-1 Studies Comparing Proprioception Between Patients after Anterior Cruciate Ligament Reconstruction (ACLR) and Controls Study

Sample Details

Proprioception Outcome Measure

ACLR Group Equivalent to Control Group Al-Othman,

22 ACLR, all male, all PT graft, 1–6 yr post surgery (mean 3.6 yr), 30 controls

15

2004

Joint position sense (standing position)

16

Ochi et al, 1999

23 ACLR, 13M:10F, 22 HS graft, 1 fascia lata graft, minimum 18 mo postsurgery, 14 controls

Joint position sense

(9M:5F) Roberts et al,

20 ACLR, 15M:5F, all PT grafts, mean 24 mo postsurgery, 19 controls (14M:5F)

Joint position sense

10 ACLR, 5M:5F; 8 PT grafts, 2 HS grafts, mean 31.6 mo postsurgery, 10 controls (5M:5F)

Joint position sense

200017 Co et al, 199318

Threshold to detect passive movement Risberg et al,

20 ACLR, 8M:12F, all PT grafts, 11–32 mo postsurgery (mean 24 mo), 10 controls (5M:5F)

199919

Threshold to detect passive movement

ACLR Group Worse than Control Group 45 ACLR, 33M:12F, all PT grafts, 1–7 yr postsurgery (mean 3.2 yr), 20 age-matched controls

Joint position sense

Bonfim et al,

10 ACLR, 7M:3F, 12–30 mo postsurgery (mean 18 mo), 10 controls (7M:3F), height and

Joint position sense

200321

weight matched

Hamstring muscle latency

Barrett et al, 199120

Performance at maintaining upright stance Threshold to detect passive movement Roberts et al,

20 ACLR, 15M:5F, all PT grafts, mean 24 mo postsurgery, 19 controls (14M:5F)

17

Threshold to detect passive movement

2000

Kaneko et al,

17 ACLR, 8M:9F, all HS/Leeds-Keio grafts, 2–3 mo post surgery, 18 controls, 20 athletes

Maximum voluntary isometric

200222

(training control group)

contraction

Shiraishi et al,

53 ACLR, 22M:31F, all facia lata grafts, minimum 2 yr post surgery, 30 controls (15M:15F)

Stabilometric assessment

23

1996

F, Female; HS, hamstring; M, male; PT, patellar tendon.

rehabilitation programs following ACL reconstruction (for an example, see Risberg et al11). However, there is very little literature on the effects of the inclusion of such exercises. Liu-Ambrose et al12 studied 10 patients at a minimum of 6 months following ACL reconstruction with a semitendinosus tendon graft. They were randomly allocated to an isotonic strength-training program or a proprioceptive training program. Both programs involved three sessions per week for a period of 12 weeks. The proprioceptive training program was based on previously described exercises. Progression was achieved by decreasing the base of support, decreasing the stability of the surfaces on which the exercises were performed, increasing the number of repetitions, reducing visual feedback, and increasing the speed and

complexity of the tasks. Progression of the strength-training program was achieved by increased loading. Outcome measures included average isokinetic torques for the quadriceps and hamstring muscle groups at 45 degrees/sec, two hop tests (single leg hop for distance and single leg timed hop), and the peak torque time of the hamstring muscle group. The latter is the time to generate maximal torque in response to a sudden forward movement of the dynamometer arm. The proprioceptive training group demonstrated greater percentage gains in average isokinetic torques for concentric quadriceps contraction and eccentric hamstring contraction in the operated limb. However, it should be noted that the proprioceptive training group had lower 537

Anterior Cruciate Ligament Reconstruction TABLE 68-2 Longitudinal Studies Study

Sample Size

Testing and Follow-

Proprioception Outcome

Up Time

Measures Joint position sense

Fremery

Group 1:

Group 1: within 12

et al,

acute ACL

days of injury

20008

rupture,

Group 2: before

N ¼ 10

surgery, 3 mo, 6 mo,

Group 2:

and 3–4 yrs after ACLR

chronic ACL

Results Summary

Acute ACL worse than chronic ACL group.

▪ Reproduction of passive positioning Chronic ACL group worse than control at a constant velocity

preoperatively but showed significant improvement

▪ Testing intervals of extension

6 mo after ACLR with values similar to control

(0–20 degrees), mid-range (40–60

group and contralateral side, except for mid-range

degrees), flexion (80–100 degrees)

positions. Continued to improve to 3 yr, although

rupture,

a small deficit was still present for mid-range

N ¼ 20

positions.

Control, N ¼ 20 Iwasa

ACL rupture,

Before surgery, then

et al,

N ¼ 38

every 3 mo for 24 mo

7

after ACLR

2000

Joint position sense

Significant improvement from preoperative values

▪ Active reproduction of passive knee position

seen from 9 mo onward. Most patients improved by 18 mo, but 21% failed to show any improvement.

▪ Tested every 5 degrees from 5–25 degrees of flexion ACL rupture,

Before surgery, 3 wk,

et al,

N ¼ 26

6 wk, 3 mo, and 6 mo

20034

Control,

after ACLR

Reider

N ¼ 26

Joint position sense

Joint position sense: Reconstructed knee equivalent

▪ Active reproduction of passive knee position

or better than both contralateral knee and control group at all time points.

▪ 10 randomly selected positions Threshold to detect passive movement ▪ 15 degrees start position with the knee moved into flexion or

Threshold to detect passive movement: ACL group worse than control group preoperatively but no difference at any other time point after reconstruction.

extension Valeriani

ACL rupture,

Before surgery, greater Threshold to detect passive movement:

et al,

N¼7

than 2 yr after ACLR

199924

ACL group worse than contralateral side

40 degrees start position with movement preoperatively and showed no improvement after between 30 and 40 degrees

ACL reconstruction.

ACLR, Anterior cruciate ligament reconstruction.

baseline average isokinetic torque values for both quadriceps and hamstring muscle groups. This may relate to the greater proportion of females or to the shorter time from surgery in this group. There was no difference between the groups for the hop tests or in peak torque time. In a larger study of 29 patients, Cooper et al13 compared two different rehabilitation protocols following primary ACL reconstruction. Thirteen subjects in each group had undergone a four-strand hamstring tendon reconstruction, with the remainder having had a patellar tendon reconstruction. The patients were randomized to one of two 6-week physiotherapy programs, commencing between 4 and 14 weeks postoperatively, once they had achieved the following criteria: ability to walk without aids, 0 to 120 degrees of range of motion in the operated knee,

538

straight leg raising without any extensor lag, and no or minimal joint effusion. Both physiotherapy programs consisted of two 40- to 60-minute physiotherapy sessions per week and a 1-hour home exercise program on the other days. The proprioceptive and balance exercise program was based on previously described exercises used for nonoperative management of ACL ruptures, which were adapted to suit wobble boards, mini trampolines, inflatable balance discs, and exercise balls. The strengthening program used exercises designed to improve muscular strength and endurance but did not specifically address balance or proprioception. At the conclusion of the 6-week program there were no differences between the two groups in terms of the Cincinnati Knee Rating System, the Patient Specific Functional

Proprioception and Anterior Cruciate Ligament Reconstruction Scale, or range of knee motion. Three hop tests (single leg hop for distance, timed 6-meter hop, and the single leg crossover triple hop for distance) were used as an objective measure of neuromuscular function. No differences were seen between the two groups. In both of these studies the proprioception-orientated program did not appear to confer any advantage in terms of tests of neuromuscular function. Interestingly, neither study used a specific test of proprioception, although the peak torque time test used by Liu-Ambrose et al included a sensory component. The benefits of such proprioceptive training programs therefore remain to be demonstrated. Not only do the effects of such training need to be more clearly established, but also the question of whether proprioception per se can be trained at all still needs to be answered. As Aston-Miller et al14 have noted, scenarios in which proprioception might be improved remain largely theoretical. If proprioception can indeed be improved by training, there remains the issue of what such improvement might achieve. The time required to develop protective muscle contraction in response to a stimulus is such that successful proprioceptive training might only be able to prevent injury as a result of relatively slow provocations, rather than the more rapidly applied forces that occur in a sporting situation. Thus the aim of proprioceptive training following ACL reconstruction needs to be clarified. Is it to restore normal function, to improve function beyond the individual’s preinjury level, or to prevent reinjury? If it is the latter, perhaps it is the improved patterns of muscular contraction as well as the awareness of and attention to various cues that are the real benefits of such training. Clearly, further studies are required to establish the role of proprioceptive training following ACL reconstruction.

References 1. Schultz RA, Miller DC, Kerr CS, et al. Mechanoreceptors in human cruciate ligaments. A histological study. J Bone Joint Surg 1984;66A:1072–1076. 2. Schutte MJ, Dabezies EJ, Zimny ML, et al. Neural anatomy of the human anterior cruciate ligament. J Bone Joint Surg 1987;69A:243–247. 3. Barrack RL, Skinner HB, Buckley SL. Proprioception in the anterior cruciate deficient knee. Am J Sports Med 1989;17:1–6. 4. Reider B, Arcand MA, Diehl LH, et al. Proprioception of the knee before and after anterior cruciate ligament reconstruction. Arthroscopy 2003;19:2–12. 5. Pap G, Machner A, Nebelung W, et al. Detailed analysis of proprioception in normal and ACL-deficient knees. J Bone Joint Surg 1999;81B:764–768.

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6. Beard DJ, Kyberd PJ, Fergusson CM, et al. Proprioception after rupture of the anterior cruciate ligament. An objective indication of the need for surgery? J Bone Joint Surg 1993;75B:311–315. 7. Iwasa J, Ochi M, Adachi N, et al. Proprioceptive improvement in knees with anterior cruciate ligament reconstruction. Clin Orthop Relat Res 2000;Dec:168–176. 8. Fremerey RW, Lobenhoffer P, Zeichen J, et al. Proprioception after rehabilitation and reconstruction in knees with deficiency of the anterior cruciate ligament: a prospective, longitudinal study. J Bone Joint Surg 2000;82B:801–806. 9. Cooper RL, Taylor NF, Feller JA. A systematic review of the effect of proprioceptive and balance exercises on people with an injured or reconstructed anterior cruciate ligament. Res Sports Med 2005;13:163–178. 10. Beard DJ, Dodd CA, Trundle HR, et al. Proprioception enhancement for anterior cruciate ligament deficiency. A prospective randomised trial of two physiotherapy regimens. J Bone Joint Surg 1994;76B:654–659. 11. Risberg MA, Mork M, Jenssen HK, et al. Design and implementation of a neuromuscular training program following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther 2001;31:620–631. 12. Liu-Ambrose T, Taunton JE, MacIntyre D, et al. The effects of proprioceptive or strength training on the neuromuscular function of the ACL reconstructed knee: a randomized clinical trial. Scand J Med Sci Sports 2003;13:115–123. 13. Cooper RL, Taylor NF, Feller JA. A randomised controlled trial of proprioceptive and balance training after surgical reconstruction of the anterior cruciate ligament. Res Sports Med 2005;13:217–230. 14. Ashton-Miller JA, Wojtys EM, Huston LJ, et al. Can proprioception really be improved by exercises? Knee Surg Sports Traumatol Arthrosc 2001;9:128–136. 15. Al-Othman AA. Clinical measurement of proprioceptive function after anterior cruciate ligament reconstruction. Saudi Med J 2004;25:195–197. 16. Ochi M, Iwasa J, Uchio Y, et al. The regeneration of sensory neurones in the reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1999;81B:902–906. 17. Roberts D, Friden T, Stomberg A, et al. Bilateral proprioceptive defects in patients with a unilateral anterior cruciate ligament reconstruction: a comparison between patients and healthy individuals. J Orthop Res 2000;18:565–571. 18. Co FH, Skinner HB, Cannon WD. Effect of reconstruction of the anterior cruciate ligament on proprioception of the knee and the heel strike transient. J Orthop Res 1993;11:696–704. 19. Risberg MA, Beynnon BD, Peura GD, et al. Proprioception after anterior cruciate ligament reconstruction with and without bracing. Knee Surg Sports Traumatol Arthrosc 1999;7:303–309. 20. Barrett DS. Proprioception and function after anterior cruciate reconstruction. J Bone Joint Surg 1991;73:833–837. 21. Bonfim TR, Jansen Paccola CA, Barela JA. Proprioceptive and behavior impairments in individuals with anterior cruciate ligament reconstructed knees. Arch Phys Med Rehabil 2003;84:1217–1223. 22. Kaneko F, Onari K, Kawaguchi K, et al. Electromechanical delay after ACL reconstruction: an innovative method for investigating central and peripheral contributions. J Orthop Sports Phys Ther 2002;32:158–165. 23. Shiraishi M, Mizuta H, Kubota K, et al. Stabilometric assessment in the anterior cruciate ligament-reconstructed knee. Clin J Sport Med 1996;6:32–39. 24. Valeriani M, Restuccia D, Di Lazzaro V, et al. Clinical and neurophysiological abnormalities before and after reconstruction of the anterior cruciate ligament of the knee. Acta Neurol Scand 1999;99:303–307.

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69 CHAPTER

Chadwick C. Prodromos Brian T. Joyce

PART P STABILITY RESULTS

Stability Results After Anterior Cruciate Ligament Reconstruction The primary purpose of anterior cruciate ligament reconstruction (ACLR) is to restore knee stability. This chapter will provide meta-analytic data on hamstring, bone–patellar tendon–bone (BPTB), quadriceps tendon, and allograft stability. The stability data are measured by instrumented Lachman testing, usually but not exclusively KT-1000 (Medmetric, San Diego, CA). Pivotshift data are not included because the high interobserver variability makes it impossible to quantify and it is an insensitive test in the nonanesthesitized patient.1 Although it is theoretically possible to have normal stability with instrumented Lachman testing and still have a pivot slide or even pivot shift present, this can only happen if the graft is put in a very vertical position. The data in this chapter are from the peer-reviewed literature, and the authors of these studies are all accomplished knee surgeons who are unlikely to place vertical grafts. Thus the data shown should be a good index to the relative stabilities of the knees tested.

STUDY CRITERIA All studies met three criteria for inclusion, as follows: 1 Minimum 2-year follow-up 2 Application of at least 30 pounds or maximum manual testing force 3 Stratified presentation of stability data, not just averages

540

STATISTICAL METHODS Meta-analytic methods were used to compare the groups. Weighted means for normal and abnormal stability were generated as follows: For each treatment group, the proportion of individuals for an outcome event was determined by adding the number of events that occurred through all studies and dividing by the number of the patients in all the studies. The number of patients for any single-center, but not multi-center, study was capped at 100 to avoid disproportionate influence of any given study. In any study, if the number of patients for a given outcome was not recorded, the study was eliminated from the analysis of that outcome. For example, with one exception, if a study did not record the number of patients who have less than 2 mm of difference, then the study was not included in the <2 mm comparison.2–66

RESULTS Table 69-1 shows all studies broken down by graft and then by fixation type for all graft types.

Only About Half of Reconstructed Knees Achieve Stability Symmetrical with the Other Knee The goal of ACL surgery is to restore the preinjury level of stability, which should be the same as that of the other knee. True symmetry is (Text continued on p. 547)

TABLE 69-1 Clinical Series Divided by Graft and Fixation Method Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

>7 Fixation–

Pop.

Fixation–

Tib

Fem

0

Sc-WS

EB

HAMSTRING GROUPS EB2–4HS: Endobutton used on femur, second -generation fixation used on tibia (Subgroup 1) Cooley*

2001

4ST

20

100

0

Eriksson

2001

4ST

74

43

50

7

Sc-WS

EB

Feller*

2003

4STG

27

85

15

0

Sc-WS

EB

Gobbi*

July

4ST

40

90

8

2

Fastlok

EB

4ST

80

90

9

1

Fastlok

EB

Sc-WS

EB

ST-Buckle

EB

2003 Gobbi*

Sept 2003

Prodromos*

2005

4STG

98

86

Yasuda*

2004

4STG

57

80

396

80

Weighted mean (Subgroup 1)

97

14

14

14

3

3

3

0

14

0 0

0

0

1.7

OC-4HS: Other cortical 4HS (XP-4HSþSC -4HSþBu-4HS) (Subgroup 2)

Aglietti

2004

4STG

60

67

43

0

WL

BMS

Howell*

1999

4STG

67

91

6

3

2ST or LW

BMS

Harilainen

2005

4STG

25

72

8

20

Sc-LW

Transfx

Fabbriciani

2005

4STG

18

61

28

0

ISþST

Transfix

STþSc-WS

Sc-Lp

Weighted mean (Subgroup 3)

72

73

4.1

Sc-4HS: cortical screw on tibia and femur (Subgroup 4) Aglietti

Feb

4STG

30

23

47

30

1997

or Sc-WS

Goradia*

2001

3STG

93

90

Howell

1999

4STG

41

90

9

1 3

1

Sc-LW

Sc-LW

7

Sc-Lp

2 Sc-LWs (continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

XP-4HS: Cross-pin femoral fixation (Subgroup 3)

69

541

542 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

Pop. Weighted mean (Subgroup 4)

6–7

>7 Fixation– Tib

78

Fixation– Fem

7.8

Bu-4HS: simple button on tibia and/or femur (Subgroup 5) Hamada*

2000

4STG

86

81

94

3

5

2

0

Bu or Sc-WS Bu or Sc-WS

Maeda

1996

4STG

41

63

73

17

10

Bu or Sc-WS Bu or Sc-WS

Noojin

2000

4ST

65

71

83

Williams

2004

4STG

79

71

82

Weighted mean (Subgroup 5)

73

85

Weighted mean (OC-4HS with extrapolation)

74

11 12

6

Bu or Sc-WS EB

6

St or IS or Bu EB

4.7 5.4

(Subgroup 2) Weighted mean (OC-4HS without extrapolation)

72

(Subgroup 2) AIS-4HS: Augmented interference screw fixation: 2IS plus augmentation Hill*

2005

4STG

21

86

14

0

ISþSt

IS

Charilton

2003

4STG

36

72

17

11

IS

IS

Harilainen

2005

3ST/4STG

29

62

21

17

IS

IS

Hill

2005

4STG

27

74

26

0

IS

IS

Scranton*

2002

4STG

120

88

3

IS

IS

Shaieb

2002

4STG

22

45

41

14

IS

IS

Wagner

2005

4STG

55

69

31

0

IS

IS

2IS-4HS: Double interference screw used (Subgroup 6)

9

Weighted mean (Subgroup 6)

75

5.4

WEIGHTED MEAN (All 4HS with extrapolation)

76.3

4.2

WEIGHTED MEAN (All 4HS without extrapolation)

77.2

4.2

2HS

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

>7 Fixation–

Pop. 66

39

Fem

NI

St-Buckle

Aglietti

1996

2STG

62

50

Anderson

2001

2STG

34

62

38

NI

St

Anderson

2001

2STG

33

62

48

NI

NI

Beynnon

2002

2STG

22

St

ST-Buckle

Feagin

1997

2ST

91

17

Sc-LW

BB

Meyestre

1998

2ST

27

18

BB

Sc-LW or

45

26

11

Fixation–

Tib

55

56

Clip O’Neill

1996

2STG

40

75

Nebelung

1998

2ST

29

55

WEIGHTED MEAN (all 2HS)

83

18

10

35

54

7

St

St

10

St-Buckle

EB

13

BTB GROUPS 2IS BTB: two interference screws used; both tibia and femur (Subgroup 7) 2004

BTB

60

65

35

0

IS

IS

Arciero

1996

BTB

51

73

20

7

IS

IS

Arciero

1996

BTB

31

65

25

9

IS

IS

Bach

1995

BTB

62

90

5

5

IS

IS

Bach

1998

BTB

100

83

14

3

IS

IS

Bach

1998

BTB

94

70

26

4

IS

IS

Barrett*

1996

BTB

83

89

10

1

IS

IS

Beynnon

2002

BTB

22

IS

IS

Eriksson

2001

BTB

80

3

IS

IS

Feagin

1997

BTB

91

11

IS

IS

Marumo

2000

BTB

42

28

IS

IS

O’Neill

1996

BTB

40

78

93

17

2

5

IS

IS

O’Neill

1996

BTB

45

78

87

20

11

2

IS

IS

77 49

23 48

62

10

5

(continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

Aglietti

69

543

544 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

>7 Fixation–

Pop.

IS

IS

1998

BTB

75

67

29

4

Sgaglione

1997

BTB

45

75

18

7

IS

IS

Sgaglione

1997

BTB

41

78

15

7

IS

IS

Shaieb

2002

BTB

24

79

8

13

IS

IS

Tan

1997

BTB

41

3

IS

IS

Wagner

2005

BTB

55

5

IS

IS

Weighted mean (Subgroup 7)

7

55

40

68

1

Fem

Plancher

90

3

Fixation–

Tib

5.0

O-BTB: Other BTB fixation: non-interference screw fixation on tibia, femur, or both (Subgroup 8) Aglietti

Feb

BTB

30

40

43

17

Sc-WS

Sc-WS

BTB

89

49

35

16

ISþBu

IS–Bu

56

32

12

ISþSP

PFBþSP

17

IS

Sc-WS

WS

EB

PFB

PFB

St

IS

1997 Aglietti

Mar 1997

Aglietti

1992

BTB

62

Aglietti

1991

BTB

65

Anderson

2001

BTB

35

Barrett

2002

BTB

37

Buss

1993

BTB

56

64

Feller*

2003

BTB

21

95

5

0

Sc-WS

PFB

Gobbi*

July

BTB

40

90

8

2

IS

EB

BTB

40

78

10

12

ISþBu

63 71

20 29

86 84

8 29

6 9

7

2003 Heier

1997

ISþBu or St

Hertel

2005

BTB

95

59

41

O’Brien

1991

BTB

79

76

Patel

2000

BTB

32

87

Shelbourne

2000

BTB

100

84

0

ISþBu

PFBþBu

4

ISþBu

Bu

13

0

Sc-LW

IS

13

2

Bu

Bu

16 4

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

Pop.

>7 Fixation– Tib

Weighted mean (Subgroup 8)

63

7.4

T-BPTB: Total BPTB: 21S-BPTB and O-BPTB combined

66

5.9

Fixation– Fem

weighted mean Quadriceps tendon graft Lee

2004

Quad

67

T-autograft

75

19

71

6.0 5.2

ALLOGRAFT SERIES BPTB: Nonirradiated (Subgroup 9) Barrett

2005

10-mm

38

74

86

5

7.0

SPþIS or Bu

BPTB Bach*{

2005

10-mm

IS, EB, or

FF

IS/EB 60

82

95

5

0.0

36

65

75

19

5.6

27

4.0

2

IS

IS

FF

IS

IS

IS

IS

FF

IS

IS

IS

IS

IS

FF

BPTB Kleipool

1998

10-mm BPTB

Siebold{

2003

10-mm

183

58

15

BPTB 1996

BPTB

64

20.0

Peterson{

2001

15-mm

30

63

73

27

0.0

30

63

73

23

3.3

IS

IS

FF

64

45

52

33

12.0 16

IS

IS

FF

3

BPTB Shelton

1997

15-mm BPTB

Noyes{

1991

9-10-mm BPTB

Weighted mean (Subgroup 9)

62

11.5

FF

BPTB: Irradiated (Subgroup 10) Noyes{ Gorschewsky

{

FF 1997

BPTB

34

44

2005

Tutoplast

85

27

32

24.0 30 45

2.5 Mrad IS

IS

1.5 Mrad/ acetone (continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

Harner

69

545

546 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

Pop.

>7 Fixation–

Fixation–

Tib

Fem

IS

IS

CP

St/IS

IS

FF

IS

IS

FF or FD

St

St

D

IS

IS

FF or FD

Sc-P

Sc-P

FF

22.0 36

WSP

WSP

FD, EO

20

3.0

?

?

FD, EO, FF

8

8.0

IS

IS

?

Weighted mean (Subgroup 10)

32

40.7

Weighted mean (all BPTB allograft)

56

17.1

Soft-tissue graft: nonirradiated Indelli Siebold

{

Nyland

2003

Achilles

50

66

32

2.0

2003

Achilles

42

71

21

2.0

2003

Tibialis

18

72

22

6.0

77

15

8.0

7

anterior Pritchard{

1995

Fascia lata

39

1994

Achilles or

181

19

Mixed grafts: nonirradiated Levitt

13.0

BPTB Noyes{

1991

9-10-mm

40

63

73

36

15

17

22

5.0

7

BPTBþITB Roberts{

1991

BPTB or BPTBþITB

Noyes

1996

Fascia lata

66

74

or BPTB {

Chang

2003

14-mm

37

65

76

16

BPTBþITB WEIGHTED MEAN (all soft tissue and mixed)

64

12

WEIGHTED MEAN (all nonirradiated grafts)

63

12

WEIGHTED MEAN (all allografts)

59

15

*After author indicates high-stability series (80% normal and
3% abnormal stability). {For allograft series, graft failures that did not result in a side-to-side laxity difference of >5 mm were included in our calculations in the >5þ column. Note: Arthrometric data were reported differently by different authors. The various categories in the column headings reflect the different criteria used in millimeters of side to side difference.
2x denotes extrapolated
2 data, as described in the text. BB, Bone bridge; BMS, bone mulch screw; Bu, simple button; CP, cryopreserved; EB, Endobutton; EO, ethylene oxide; FD, freeze-dried; FF, fresh frozen; IS, interference screw; KT Pop, KT-1000 study population; NI, natural insertion left intact; PFB, press-fit bone; Sc-Lp, graft looped around cortical screw; Sc-LW, cortical screw with ligament washer; Sc-WS, cortical screw with whipstitches; St, staple; WL, WasherLoc; BTB, bone–tendon–bone; BPTB, bone–patellar tendon–bone.

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Stability Results After Anterior Cruciate Ligament Reconstruction achieved when the side-to-side difference (SSD) between the knees is 0. Measurement error increases this criterion to 1 mm. Thus we propose a SSD of 1 mm as defining knee stability symmetry. The IKDC “normal” criterion of up to a 2-mm difference may be satisfactory, but it is not truly normal. Indeed, a 2-mm SSD is what is commonly seen with partially torn ACLs.67 When the 1-mm criterion is applied, we see the following: For all autografts, about 30% have greater than 2-mm SSD.68 The remaining 70% fall into four categories: 2 mm, 1 mm, 0, or less than 0. If we assume that one-fourth of the 70% falls into each of these four categories, then it is reasonable to estimate that one-fourth of 70%, or 18%, are exactly 2 mm different. Adding this 18% (exactly 2 mm) to the 30% (greater than 2 mm) would mean that 48% of the reconstructed population has a 2-mm or greater SSD. This leaves about 52% with 1 mm or less SSD (i.e., true symmetry with the other knee). Thus roughly one-half of the autograft ACLRs, in the hands of the experienced knee surgeons who are the authors of these studies, have stability that is either equivalent to a partially torn ACL or worse. The allograft data68 show significantly lower stability rates (see Table 69-1). Table 69-1 presents the raw data for stability from all the studies. The principal areas of interest are the “normal” and “abnormal” stability columns. Abnormal stability in most cases is equivalent to graft failure. The primary table subdivision is by graft type. These are four-strand hamstring (4HS) autograft, two-strand hamstring (2HS) autograft, BPTB autograft, and quadriceps tendon autograft and allograft. The secondary subdivision is by graft subgroup and by fixation type. Subdividing by fixation groups is possible to do with the autografts because of the large number of studies. It is only possible with the allografts to break out a BPTB/interference subgroup because of the smaller number of studies.

stability rate of 56% (P <0.001). The BPTB autograft abnormal stability rate of 5.9% was significantly lower than the BPTB allograft abnormal stability rate of 17% (P <0.001). 4 Radiated allografts had significantly lower stability rates than nonirradiated allografts. Normal and abnormal rates for radiated were 32% and 41%, respectively, versus 63% and 12% for nonirradiated grafts (P <0.001). 5 The two-strand hamstring normal stability rate of 53% and abnormal stability rate of 13% were both significantly worse than the rates for both 4HS and BPTB (P <0.001). 6 There is only one published quadriceps tendon study with 2-year follow-up and stratified stability rates. The normal stability rate was 75%, and the abnormal rate was 6%.

Stability Rate by Graft Fixation Subgroups Stability rates for these subgroups are as follows: 1 The 4HS-EB2 subgroup, which used an Endobutton on the femur and second-generation fixation on the tibia, had the highest stability rates of any graft fixation subgroup. Its normal and abnormal stability rates were 77% and 1.7%, respectively. By comparison, the 4HS group with interference screws on both the tibia and femur, 4HS-2IS, had normal and abnormal rates of 75% and 5.4%, respectively. 2 For BPTB, interference screw fixation had slightly higher stability rates than noninterference screw fixation: normal and abnormal rates of 68% and 5.0%, respectively, for interference screws versus 63% and 7.4% for noninterference screws. However, some of the overall highest stability rates were obtained by noninterference screw fixation methods.

Stability Rates by Graft Type

Aperture Versus Nonaperture Fixation

The principal findings were as follows:

For soft tissue grafts, there was no stability advantage for aperture fixation. Indeed, as just described, the 4HS-EB2 group, which had entirely nonaperture cortical fixation, had the highest stability rates of any graft fixation subgroup. Thus the so-called “bungee effect” would appear to be nonexistent. This is not surprising, as studies have shown that fixation on rigid cortical bone enhances stiffness much more than the greater length of the construct diminishes it.69 Also, variations in fixation stiffness are eliminated once the graft heals into the bone tunnel because the fixation is no longer load bearing. What really matters is how much the graft may elongate during this healing period from either slippage or plastic deformation. Neither of these is related to fixation stiffness.

1 The 4HS graft group normal stability rate of 77% was significantly higher than the BPTB rate of 66% (P < 0.001). The 4HS abnormal rate of 4.2% was significantly lower than the BPTB rate of 5.9% (P ¼ 0.029). 2 The autograft normal stability rate of 71% was significantly higher than the allograft normal stability rate of 59% (P <0.001). The autograft abnormal stability rate of 5.2% was significantly lower than the allograft abnormal stability rate of 15% (P <0.001). 3 The BPTB autograft normal stability rate of 66% was significantly higher than the BPTB allograft normal

69

547

Anterior Cruciate Ligament Reconstruction

Four-Strand Hamstring Versus Bone– Patellar Tendon–Bone Stability Rates Because BPTB has long been considered the “gold standard” for ACLR. it may be surprising to some that 4HS was found to have higher stability rates. However, as the 4HS graft is a significantly stronger graft (see Chapter 10), the excellent 4HS stability rates do make sense if modern fixation is used. Prior analyses have seemed to show that hamstring grafts had lower stability rates than BPTB.70,71 However, these studies commingled the much-lower-stability 2HS studies with the higher-stability 4HS studies. If the 2HS studies are removed, it turns out that there was no stability advantage to BPTB in those studies by comparison with 4HS. Also, many of the highest-stability 4HS series were published after those studies. They were thus not included in those analyses but contribute significantly to the higher 4HS stability rates found here.

Allograft Versus Autograft Allograft use has been steadily increasing. Surgeons who wish to avoid the morbidity of BPTB as well as the harvest of hamstrings are among the many who have been turning increasingly to allografts. The data presented here show significantly lower stability rates for allografts, with an abnormal stability rate, which usually represents graft failure, about three times higher than for autografts. These low-stability results also would indicate that ligamentization may indeed proceed differently for allogeneic tissue. This may be due in part to the less-effective and slower rate of recellularization that occurs with allografts.72 There is anecdotal evidence that late failure rates may be higher for allografts,73,74 which may be related to this same phenomenon. Many now believe that some form of sterilization is necessary for allografts over and above sterile processing (see Chapter 70). Although higher levels of radiation have been believed to provide good sterilization, they have also long been considered to decrease graft strength. However, the radiated grafts in this study had lower stability rates than the nonirradiated grafts, even though the radiation levels in these studies were below 3 MRADs.49,63 This level is below that required to kill the human immunodeficiency virus (HIV)75 but is still apparently high enough to diminish graft strength. Some have felt the answer lies in radioprotectant that allows virucidal 5 MRAD level sterilization while potentially avoiding graft weakening.76 Clinical studies to test this hypothesis are ongoing. A variety of chemical treatments of allografts are also variably carried out by different tissue banks.77,78 It is unknown how these treatments affect graft ligamentization,

548

cellular repopulation, and ultimate strength. Careful clinical follow-up will be required to assess which allograft treatments are optimal regarding both sterility and stability.

CONCLUSIONS 1 Four-strand hamstring grafts had higher stability rates than BPTB grafts. 2 Cortical fixation produced higher stability rates than aperture fixation for soft tissue grafts, indicating that no bungee effect exists. 3 Allografts had lower stability rates than autografts, with abnormal stability rates that were three times higher. 4 Radiated allografts had lower stability rates than nonirradiated allografts. 5 BPTB allografts had lower stability rates than BPTB autografts. 6 The quadriceps tendon performed similarly to BPTB in the one suitable study, but more data are needed. 7 Symmetrical knee stability appears to be restored in only about half of ACL reconstructed knees overall.

References 1. Kim SJ, Kim HK. Reliability of the anterior drawer test, the pivot shift test, and the Lachman test. Clin Orthop Relat Res 1995;317:237–242. 2. Anderson A, Snyder R, Lipscomb B. Anterior cruciate ligament reconstruction: a prospective randomized study of three surgical methods. Am J Sports Med 2001;29:272–279. 3. Beynnon B, Johnson R, Fleming B, et al. Anterior cruciate ligament replacement: comparison of bone-patellar tendon-bone grafts with two-strand hamstring grafts. J Bone Joint Surg 2002;84A:1503–1513. 4. Feagin JA, Wills RP, Lambert KL, et al. Anterior cruciate ligament reconstruction: bone-patella tendon-bone versus semitendinosus anatomic reconstruction. Clin Orthop 1997;341:69–72. 5. Meyestre J, Vallotton J, Benvenuti J. Double semitendinosus anterior cruciate ligament reconstruction: 10-year results. Knee Surg Sports Traumatol Arthrosc 1998;6:76–81. 6. O’Neill D. Arthroscopically assisted reconstruction of the anterior cruciate ligament: a follow-up report. J Bone Joint Surg 2001;83A:1329–1332. 7. Shelbourne DK, Gray T. Anterior cruciate ligament reconstruction with autogenous patellar tendon graft followed by accelerated rehabilitation: a two- to nine-year follow-up. Am J Sports Med 1997;25:786–795. 8. Gobbi A, Mahajan S, Zanazzo M, et al. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation in athletes. Arthroscopy 2003;19:592–601. 9. Aglietti P, Zaccherotti G, Buzzi R, et al. A comparison between patellar tendon and doubled semitendinosus/gracilis tendon for anterior cruciate ligament reconstruction: a minimum five-year follow-up. J Sports Traumatol Relat Res 1997;19:57–68. 10. Aglietti P, Buzzi R, Giron F, et al. Arthroscopic-assisted anterior cruciate ligament reconstruction with the central third patellar tendon. Knee Surg Sports Traumatol Arthrosc 1997;5:138–144.

Stability Results After Anterior Cruciate Ligament Reconstruction 11. Arciero RA, Scoville CR, Snyder RJ, et al. Single versus two-incision arthroscopic anterior cruciate ligament reconstruction. Arthroscopy 1996;12:462–469. 12. Bach BR, Jones GT, Hager CA, et al. Arthrometric results of arthroscopically assisted anterior cruciate ligament reconstruction using autograft patellar tendon substitution. Am J Sports Med 1995;23:179–185. 13. Bach BR, Tradonsky S, Bojchuk J, et al. Arthroscopically assisted anterior cruciate ligament reconstruction using autograft patellar tendon autograft: five- to nine-year follow-up evaluation. Am J Sports Med 1998;26:20–29. 14. Bach BR, Levy ME, Bojchuk J, et al. Single-incision endoscopic anterior cruciate ligament reconstruction using patellar tendon autograft: minimum two-year follow-up evaluation. Am J Sports Med 1998;26:30–40. 15. Buss DD, Warren RF, Wickiewicz TL, et al. Arthroscopically assisted reconstruction of the anterior cruciate ligament with use of autogenous patellar-ligament grafts: results after twenty-four to forty-two months. J Bone Joint Surg 1993;75A:1346–1355. 16. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83B:348–354. 17. Hertel P, Behrend H, Cierpinski T, et al. ACL reconstruction using bone-patellar tendon-bone press-fit fixation: 10-year clinical results. Knee Surg Sports Traumatol Arthrosc 2005;13:248–255. 18. Heier KA, Mack DR, Moseley JB, et al. An analysis of anterior cruciate ligament reconstruction in middle-aged patients. Am J Sports Med 1997;25:527–532. 19. O’Brien SJ, Warren RF, Pavlov H, et al. Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patellar ligament. J Bone Joint Surg 1991;73A:278–286. 20. Patel JV, Church JS, Hall AJ. Central third bone-patellar tendonbone anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy 2000;16:67–70. 21. Plancher KD, Steadman JR, Briggs KK, et al. Reconstruction of the anterior cruciate ligament in patients who are at least forty years old: a long-term follow-up and outcome study. J Bone Joint Surg 1998;80A:184–197. 22. Sgaglione NA, Schwartz RE. Arthroscopically assisted reconstruction of the anterior cruciate ligament: initial clinical experience and minimal 2-year follow-up comparing endoscopic transtibial and two-incision techniques. Arthroscopy 1997;13:156–165. 23. Shelbourne KD, Urch SE. Results of anterior cruciate ligament reconstruction based on meniscus and articular cartilage status at the time of surgery: five- to fifteen-year evaluations. Am J Sports Med 2000;28:446–452. 24. Tan MY, Yeo SJ, Tay BK. Anterior cruciate ligament reconstruction using patellar tendon autografts: a review of results. Singapore Med J 1997;38:529–534. 25. Barrett GR, Noojin FK, Hartzog CW, et al. Reconstruction of the anterior cruciate ligament in females: a comparison of hamstring versus patellar tendon autograft. Arthroscopy 2002;18:46–54. 26. Shaieb MD, Kan DM, Chang SK, et al. A prospective randomized comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:214–220. 27. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. J Bone Joint Surg 2004;86A:2143–2155. 28. Aglietti P, Buzzi R, D’Andria S, et al. Arthroscopic anterior cruciate ligament reconstruction with patellar tendon. Arthroscopy 1992;8:510–516. 29. Marumo K, Kumagee Y, Tanaka T, et al. Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts. J Long Term Eff Med Implants 2000;10: 251–265.

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30. Barrett GR, Treacy SH. The effect of intraoperative isometric measurement on the outcome of anterior cruciate ligament reconstruction: a clinical analysis. Arthroscopy 2000;12:645–651. 31. Aglietti P, Buzzi R, D’Andria S, et al. Reconstruction of the chronically lax anterior cruciate ligament using the middle third of the patellar tendon: a 3–9 year follow-up. Ital J Orthop Traumatol 1991;17:479–490. 32. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 33. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 34. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20:1015–1025. 35. Gobbi A, Tuy B, Mahajan S, et al. Quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a clinical investigation in a group of athletes. Arthroscopy 2003;19:691–699. 36. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 37. Williams RJ III, Hyman J, Petrigliano F, et al. Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg 2004;86A:225–232. 38. Maeda A, Shino K, Horibe S, et al. Anterior cruciate ligament reconstruction with multistranded autogenous semitendinosus tendon. Am J Sports Med 1996;24:504–509. 39. Howell SM, Deutsch ML. Comparison of endoscopic and twoincision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy 1999;15:594–606. 40. Scranton P, Bagenstose JE, Lantz BA, et al. Quadruple hamstring anterior cruciate ligament reconstruction: a multicenter study. Arthroscopy 2002;18:715–724. 41. Hill PF, Russell VJ, Salmon LJ, et al. The influence of supplementary tibial fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendons in female patients. Am J Sports Med 2005;33:94–101. 42. Nebelung W, Becker R, Merkel M, et al. Bone tunnel enlargement after anterior cruciate ligament reconstruction with semitendinosus tendon using Endobutton fixation on the femoral side. Arthroscopy 1998;14:810–815. 43. Noojin FK, Barrett GR, Hartzog CW, et al. Clinical comparison of intraarticular anterior cruciate ligament reconstruction using autogenous semitendinosus and gracilis tendons in men versus women. Am J Sports Med 2000;28:783–789. 44. Charlton WP, Randolph DA Jr, Lemos S, et al. Clinical outcome of anterior cruciate ligament reconstruction with quadrupled hamstring tendon graft and bioabsorbable interference screw fixation. Am J Sports Med 2003;31:518–521. 45. Fabbriciani C, Milano G, Mulas PD, et al. Anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendon graft in rugby players. Knee Surg Sports Traumatol Arthrosc 2005;13:2–7. 46. Harilainen A, Sandelin J, Jansson KA. Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33. 47. Goradia VK, Grana WA. A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts. Arthroscopy 2001;17:383–392. 48. Hamada M, Shino K, Horibe S, et al. Preoperative anterior knee laxity did not influence postoperative stability restored by anterior cruciate ligament reconstruction. Arthroscopy 2000;16:477–482. 49. Gorschewsky O, Klakow A, Riechert K, et al. Clinical comparison of the Tutoplasty allograft and autologous patellar tendon (bone-patellar

549

Anterior Cruciate Ligament Reconstruction

50.

51.

52.

53. 54.

55.

56.

57. 58.

59.

60.

61.

62.

63.

64.

550

tendon-bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. Am J Sports Med 2005;33:1202–1209. Roberts TS, Drez D Jr, McCarthy W, et al. Anterior cruciate ligament reconstruction using freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts: two year results in thirty-six patients. Am J Sports Med 1991;19:35–41. Pritchard JC, Drez D Jr, Moss M, et al. Long-term followup of anterior cruciate ligament reconstructions using freeze-dried fascia lata allografts. Am J Sports Med 1995;23:593–596. Kleipool AEB, Zijl JAC, Willems WJ. Arthroscopic anterior cruciate ligament reconstruction with bone-patellar tendon-bone allograft or autograft: a prospective study with an average follow up of 4 years. Knee Surg Sports Traumatol Arthrosc 1998;6:224–230. Shelton WR, Papendick L, Dukes AD. Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy 1997;13:446–449. Siebold R, Buelow JU, Bos L, et al. Primary ACL reconstruction with fresh-frozen patellar versus Achilles tendon allografts. Arch Orthop Trauma Surg 2003;123:180–185. Bach BR Jr, Aadalen KJ, Dennis MG, et al. Primary anterior cruciate ligament reconstruction using fresh-frozen, nonirradiated patellar tendon allograft: minimum 2-year follow-up. Am J Sports Med 2005;33:284–292. Barrett G, Stokes D, White M. Anterior cruciate ligament reconstruction in patients older than 40 years: allograft versus autograft patellar tendon. Am J Sports Med 2005;33:1505–1512. Chang SKY, Egami DK, Shaieb MD, et al. Anterior cruciate ligament reconstruction: allograft versus autograft. Arthroscopy 2003;19:453–462. Harner CD, Olson E, Irrgang JJ, et al. Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop Relat Res 1996;324:134–144. Indelli PF, Dillingham MF, Fanton GS, et al. Anterior cruciate ligament reconstruction using cryopreserved allografts. Clin Orthop Relat Res 2004;420:268–275. Levitt RL, Malinin T, Posada A, et al. Reconstruction of anterior cruciate ligaments with bone-patellar tendon-bone and Achilles tendon allografts. Clin Orthop Relat Res 1994;303:67–78. Noyes FR, Barber SD. The effect of an extra-articular procedure on allograft reconstructions for chronic ruptures of the anterior cruciate ligament. J Bone Joint Surg 1991;73A:882–892. Noyes FR, Barber-Westin SD. Reconstruction of the anterior cruciate ligament with human allograft: comparison of early and later results. J Bone Joint Surg 1996;78A:524–537. Noyes FR, Barber-Westin SD. Arthroscopic-assisted allograft anterior cruciate ligament reconstruction in patients with symptomatic arthrosis. Arthroscopy 1997;13:24–32. Nyland J, Caborn DNM, Rothbauer J, et al. Two-year outcomes following ACL reconstruction with allograft tibialis anterior tendons: a retrospective study. Knee Surg Sports Traumatol Arthrosc 2003;11:212–218.

65. Peterson RK, Shelton WR, Bomboy AL. Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy 2001;17:9–13. 66. Aglietti P, Buzzi R, Menchetti P, et al. Arthroscopically assisted semitendinosus and gracilis tendon graft in reconstruction for acute anterior cruciate ligament injuries in athletes. Am J Sports Med 1996;24:726–731. 67. Rijke AM, Perrin DH, Goitz HT, et al. Instrumented arthrometry for diagnosing partial versus complete anterior cruciate ligament tears. Am J Sports Med 1994;22:294–298. 68. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 69. To JT, Howell SM, Hull ML. Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation. Arthroscopy 1999;15:379–387. 70. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction: a meta-analysis. Arthroscopy 2001;17:248–257. 71. Freedman K, D’Amato M, Nedeff D, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 72. Scheffler S, Unterhauser F, Keil J, et al. Comparison of tendon-to-bone healing after soft tissue autograft and allograft ACL reconstruction in a sheep model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 73. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at symposium at the 2006 of the American Academy of Orthopaedic Surgeons, Chicago, March, 2006. 74. Siegel MG. Personal communication, May 2006. 75. Fideler BM, Vangsness CT Jr, Moore T, et al. Effects of gamma irradiation on the human immunodeficiency virus. J Bone Joint Surg 1994;76A:1032–1035. 76. Forng RY, Willkommen H, Almeida J, et al. Terminal sterilization of human tissue allografts: application of high-dose gamma irradiation using the clearant process. Unpublished data, Year. 77. Mroz TE, Lin EL, Summit MC, et al. Biomechanical analysis of allograft bone treated with a novel sterilization process. Spine J 2006;6:34–39. 78. Caborn D, Nyland J, Chang HC, et al. Tendon allograft cryoprotectant incubation and rehydration time alters mechanical stiffness properties. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006.

PART Q COMPLICATIONS

Infections in Anterior Cruciate Ligament Surgery INTRODUCTION Infection following anterior cruciate ligament (ACL) surgery is an uncommon but serious complication. The infectious process, if not controlled adequately, will jeopardize the integrity of the articular cartilage and may lead to irreversible damage of the knee joint. The low prevalence of this complication limits the experience of any individual surgeon, and the relevant literature consists of few series with small numbers of patients treated with management protocols ranging in aggressiveness from arthroscopic irrigation to radical débridement with graft and hardware removal.1–9 This chapter presents management guidelines for treatment of infections in ACL surgery, discusses the potential role of allografts in development of septic complications, and reviews management of the intraoperatively contaminated graft.

PREVALENCE OF INFECTION The prevalence of infection following ACL reconstruction is very low. In studies reporting on septic complications, the infection rate ranged from 0.14% to 1.74%1–5,7–9 (Table 70-1). Overall these eight studies reported 66 infections following 12,684 procedures, resulting in a mean infection prevalence of 0.52%.1–5,7–9 Matava et al surveyed directors of sports medicine fellowship programs about their

experience with infections after ACL surgery. 10 The 61 surgeons who responded performed on average 98 ACL reconstructions per year; 18 surgeons (30%) had treated an ACL infection within the past 2 years, and 26 (43%) had treated an infection within the past 5 years. Therefore even experienced surgeons have managed a limited number of cases in their career.

70 CHAPTER

Charalampos G. Zalavras Michael J. Patzakis

PATHOGENESIS: PREDISPOSING FACTORS Infections in ACL surgery result from contamination of the operative site with microbes, which is followed by a complex interaction of the inoculated microorganisms with the local and systemic host environment. In the presence of systemic compromise of the host, decreased vascularity of the local environment, and virulence of the microorganism, the host mechanisms may prove inadequate to eradicate the inoculated microorganisms, thus leading to development of infection.

Systemic Factors The importance of host physiology in musculoskeletal infections has been emphasized in the literature.11 Systemic host factors include comorbidities, such as diabetes mellitus, malignancy, malnutrition, immunocompromised status, or other disease that may compromise the host defense against microbial pathogens. However,

551

Anterior Cruciate Ligament Reconstruction TABLE 70-1 Prevalence of Infection Following Anterior Cruciate Ligament (ACL) Surgery Study

Number of ACL

Number of

Prevalence of

Surgeries

Infections

Infection

Burks et al3

1918

8

0.42%

Fong et al7

472

7

1.48%

3500

5

0.14%

McAllister et al

831

4

0.48%

Musso and

1094

11

1.01%

575

10

1.74%

Viola et al5

1794

14

0.78%

Williams et al1

2500

7

0.30%

Total

12684

66

0.52%

Indelli et al4 2

McCormack8 Schollin-Borg et al9

systemic host factors are not as prevalent in ACL surgery compared with other procedures because most patients undergoing ACL reconstruction are relatively young, active, and healthy. In the series with postoperative infections after ACL surgery presented in Table 70-1, the mean age of the patients ranged from 21 to 34 years, and no comorbidities were reported. A study on persistent infections reported comorbidities in three of five patients.6

Local Factors Local risk factors for infection after ACL reconstruction include previous or concomitant secondary knee procedures.1–3 Williams et al1 reported that six of seven patients with infections had concomitant procedures performed, such as “outside-in” meniscal repair with polydiaxone (PDS) suture, medial collateral ligament reconstruction, and posterolateral corner reconstruction. In the series of McAllister et al,2 three of four patients had previous knee surgery and two of four patients had an “inside-out” meniscal repair. Burks et al3 reported that five of eight patients in their series had concomitant procedures performed at the time of ACL reconstruction. In the series of Musso and McCormack,8 five of nine patients also underwent meniscal procedures. Potential explanations include the increased operative time, additional or larger incisions with more extensive dissection in cases where complex reconstructive surgery takes place, and implantation of foreign material such as suture. However, other authors did not report concomitant procedures in their infected ACL reconstructions.4 The role of

552

secondary procedures in development of infection is not clear, as the existing studies have not performed a comparison between infected and control patients.

Contamination Contamination of the operative site may occur from use of inadequately sterilized instruments or implantation of contaminated grafts. Contaminated in-flow cannulas have been identified as the source of infection. Viola et al reported a sudden increase in their infection rate from 0.1% in the period from 1991 to 1996 (2 in 1724 ACL reconstructions) to 14.2% in the period from December 1996 to February 1996 (10 of 70).5 “Sterile” sets of in-flow cannulas used for ACL reconstructions were found to be contaminated with coagulase-negative Staphylococcus. Following the discovery of the contaminated instruments, the infection rate dropped to 0.25% (1 in 400 cases). In another study, contamination with coagulase-negative Staphylococcus was present on supposedly sterile suture clamps on graft preparation boards.9 Inadequate disinfection of arthroscopic equipment12 and flash sterilization of meniscus repair cannulas with residual debris in the lumen13 have been reported as potential causes of septic arthritis following arthroscopy. Undetected intraoperative contamination of the graft may take place as well. Hantes et al14 obtained culture specimens before implantation of autografts and reported that cultures were positive in 12% of cases (7 of 60). Diaz-de-Rada et al15 reported that allograft cultures were positive in 13% of cases (24 of 181). The source and significance of this contamination remain unclear. However, in both studies no clinical infections developed after a minimum 1-year follow-up. Contamination of allografts used in ACL reconstruction as a source of infection is discussed in detail later.

Biofilm Formation Biofilm formation is a key mechanism for persistence or recurrence of infection. The biofilm is an aggregation of microbial colonies enclosed within an extracellular polysaccharide matrix (glycocalyx) that adheres on the surface of implants or devitalized tissue.16,17 Gristina and Costerton18 reported that 59% (10 of 17) of orthopaedic biomaterial– related infections had positive findings of glycocalyx-enclosed organisms on electron microscopy. Presence of an avascular graft and metal fixation devices in ACL reconstruction create conditions conducive to biofilm development if a postoperative infection is not treated early and adequately. The biofilm protects the organism from antibiotics and host defense mechanisms, such as antibody formation and phagocytosis; therefore infection may exist in a

Infections in Anterior Cruciate Ligament Surgery

70

2 months), and late (more than 2 months).1 The mean time for development of infection following ACL surgery ranged from 8 days5 to 25 days8 (Table 70-2).

subclinical state and eventually recur. In chronic musculoskeletal infections, removal of the biofilm by removal of implants and débridement of devitalized tissue are necessary for successful treatment of infection.19

Laboratory Findings

DIAGNOSIS

Peripheral white blood cell (WBC) count may be within normal limits. In contrast, markers of inflammation, such as the C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), are elevated and are helpful in the diagnosis. Elevated CRP has been invariably reported in patients with ACL postoperative infections; the mean CRP levels ranged from 2.6 mg/dL2 to 12.3 mg/dL7 in the existing studies (see Table 70-2). Elevated levels of ESR have been similarly reported in the literature, with mean values ranging from 48 mm/hr3 to 87 mm/hr.5 The anticipated increase of ESR and CRP in the immediate postoperative period may confound the diagnostic picture in the first week. Viola et al5 evaluated 15 patients with a normal postoperative course and reported that 5 days after ACL surgery they had elevated CRP levels with a mean of 2.7 mg/dL (range 0.6–12.3 mg/dL). Margheritini et al20 reported a postoperative increase of both CRP and ESR peaking on the third and seventh days, respectively. The CRP returned to nearly normal levels by postoperative day 15, which was faster than the ESR; the authors concluded that CRP is a more sensitive indicator of postoperative septic complications.20 Elevated levels of CRP beyond the postoperative day 15 strongly point toward a septic etiology for the patient’s symptoms. Aspiration of the involved knee joint is necessary and yields turbid fluid that should be sent for Gram stain, WBC count and differential, and culture (both aerobic and

Clinical Findings The typical clinical presentation includes knee pain, effusion, local erythema, and warmth. Such symptoms in the first 2 postoperative days may be due to the procedure, but persistence beyond the second day, especially if the pain is increasing, should raise the suspicion of infection. Fever is usually present. Drainage from the surgical incision may be present. An alterative presentation is with emergence of symptoms at a later time following a symptom-free interval. In some cases, the clinical picture may consist of mild pain, effusion, and difficulty performing physical therapy without the systemic signs of infection. As Burks et al3 warned, the surgeon should not interpret this relatively benign presentation as the absence of infection. A high index of suspicion is necessary, and patients who do not demonstrate steady postoperative improvement; present with increased pain, effusion, or stiffness following a symptom-free interval; or develop systemic symptoms (fever, chills, malaise) should be considered to have a septic knee until proven otherwise. Patients should be instructed to contact their physician immediately if knee symptoms develop postoperatively, which should be evaluated without delay. Infections have been classified as acute (presenting less than 2 weeks postoperatively), subacute (2 weeks to

TABLE 70-2 Time for Development of Infection and Laboratory Findings Study

Onset of Infection (days)

CRP (mg/dL)

ESR (mm/hr)

Blood WBC

Aspirate WBC

(103/mm3)

(103/mm3)

Aspirate PMNs (%)

Burks et al3

19 (NA)

NA

48 (1–110)

8.4 (4.7–10.6)

61 (18–100)

94 (91–97)

Fong et al7

24 (7–56)

12.3 (2.5–21.5)

72 (10–95)

11.7 (10–16)

NA

93 (90–95)

20 (9–34)

NA

NA

NA

91 (64–129)

NA

11 (8–18)

2.6 (2.0–3.2)

79 (19–118)

9.7 (4–11)

50.8 (7.7–81.2)

90 (NA)

Musso et al

25 (4–42)

5.5 (1.6–7.6)

50 (16–76)

9.4 (6.2–13.5)

77.2 (32.2–222)

94 (90–98)

Schollin-Borg et al9

9 (4–20)

9.2 (1.0–19.9)

62 (22–102)

8.4 (7.4–10.6)

49.4 (NA)

92 (NA)

8 (2–20)

10 (3.7–18.6)

87 (56–191)

10.2 (7.5–19.9)

NA

NA

22 (3–79)

NA

82 (50–112)

10.8 (616)

75.4 (27–136.7)

92 (NA)

Indelli et al

4

McAllister et al2 8

Viola et al

5

Williams et al

1

CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; NA, not applicable; PMN, polymorphonuclear cell; WBC, white blood cell.

553

Anterior Cruciate Ligament Reconstruction anaerobic). The mean WBC count has ranged from 49,400 per mm3 in the study by McAllister et al2 to 91,000 per mm3 in the study by Indelli et al.4 Despite this variability in the absolute number of WBC in the joint aspirate, the differential count reveals mean values of 90% to 94% of polymorphonuclear (PMN) cells (see Table 70-2).

TABLE 70-3 Microbiology of Postoperative Autograft Anterior Cruciate Ligament Infections Study

Burks

Number of

Identified

Cases with

Cases with

Organisms

Joint Aspirate

Positive

(Number)

Cultures

Cultures (%)

4

4 (100%)

SA(3), PA (1)

7

7 (100%)

SA (4), PS (3), EB

et al3

Imaging Studies

Fong 7

Magnetic resonance imaging (MRI) can help determine the extent of infection and the presence of any extraarticular fluid collections that otherwise could have been missed.21

(1), KL (1)*

et al

6

Indelli

6 (100%)

et al{4

SA (3), SE (2), NHS (1)

McAllister

4

4 (100%)

SA (4)

9

5 (560%)

CNS (5)

10

8 (80%)

CNS (6), SA (1),

et al2

Microbiology

Musso

Forty-three (74%) of 58 joint fluid cultures were positive in studies reporting on postoperative autograft ACL infections (Table 70-3). Staphylococcus aureus was the most common pathogen, present in 21 of 43 cases with positive cultures (48.5%). Coagulase-negative Staphylococcus (including S. epidermidis) was cultured in 17 of 43 cases (39.5%). Overall, septic arthritis following ACL surgery was caused by staphylococcal species in the vast majority of cases (88%). Anaerobic infections (Peptostreptococcus, Propionibacteriaceae) were present in 11.5% of cases (5 of 43). Gram-negative bacteria (Pseudomonas aeruginosa, Enterobacter, Klebsiella) were relatively uncommon and were identified in 7% of cases (3 of 43). Case reports of unusual infections following autograft ACL reconstruction have been reported, including infection with S. caprae,22Erysipelothrix rhusiopathiae,23 mucormycosis,24 and necrotizing fasciitis.25 Reports of infections following allograft ACL surgery are discussed later.

Number of

et al8 Schollin9

PB (1)

Borg et al Viola

11

2 (18%)

SE (2)

7

7 (100%)

SA (6), SE (2), PS

et al5 Williams et al1 Total

(1)* 58

43 (74%)

SA (21) CNS/SE (17) Anaerobes: PS, PB (5) Gram negative: PA, EB, KL (3)

CNS, Coagulase-negative Staphylococcus; EB, Enterobacter; KB, Klebsiella; NHS, nonhemolytic Streptococcus; PA, Pseudomonas aeruginosa; PB, Propionibacteriaceae; PS, Peptostreptococcus; SA, Staphylococcus aureus, SE, Staphylococcus epidermidis. *Numbers do not add up to the total number of positive cultures because some

MANAGEMENT PROTOCOL Prompt management is imperative for two reasons. First, evacuation of the purulent effusion as soon as possible will minimize the duration of the adverse effect of the secreted enzymes and toxins that degrade proteoglycans and collagen, thereby leading to damage of the articular cartilage. Second, a delay in treatment will allow the pathogens to gradually form a biofilm on the avascular graft and on implanted hardware as time progresses. Biofilm formation will preclude eradication of the pathogens; in this case the infection may be initially controlled only to recur later. The management protocol consists of two key components: antibiotic administration and surgical management with irrigation and débridement of the knee joint. 554

patients had more than one organism present. {

Two of six grafts were allografts.

Antibiotic Administration Intravenous antibiotics should be started as soon as possible. Empirical coverage should be provided for Gram-positive cocci and then modified according to the culture and sensitivity results. Vancomycin can be used as the initial antibiotic because it is active against coagulase-negative staphylococcal species and against oxacillin-resistant S. aureus, which is becoming a progressively more common pathogen. When culture results become available, antibiotic therapy should be modified accordingly and continued for 6 weeks. In infections developing after implantation of an allograft, broad-spectrum antibiotic therapy may be preferable

Infections in Anterior Cruciate Ligament Surgery due to the potential for allograft contamination with anaerobes or Gram-negative organisms.

Surgical Management Surgical management of septic arthritis with irrigation and débridement of the knee joint is a critical component of the management protocol. Some investigators have suggested that initiation of antibiotics may suffice, and they have proposed an expectant policy, reserving surgical management for cases not responding to antibiotics.5,8 However, this approach has several disadvantages: evacuation of the purulent effusion is incomplete, débridement of the joint is not performed, and thereby an increased bacterial count remains, which may compromise eradication of the infection. Therefore immediate surgical management has been proposed by several authors.1–3,7,9 In a survey of directors of sports medicine fellowship programs,10 98% of respondents (60 of 61) selected surgical irrigation as part of their management protocol in conjunction with intravenous antibiotics. Details of the surgical management remain controversial. Is arthroscopic or open débridement preferable? What should be the fate of the graft and any implanted hardware? Unfortunately, definitive answers to these questions cannot be provided based on the limited existing literature, but we will attempt to summarize and present the available data for the initial management of infections and for the management of persistent cases.

Initial Management Irrigation and Débridement Arthroscopic irrigation and débridement appear to be the most commonly used methods of initial management for the patient presenting with a septic knee following ACL surgery.1–5,7,9 In addition to irrigation of the joint with copious amounts of saline, débridement of necrotic or inflamed tissue should be performed. Synovectomy has been proposed by some authors1,2 in order to decrease the bacterial count and aid in the resolution of infection. Particular attention should be paid to the graft; its stability and macroscopic appearance should be carefully evaluated, and débridement should include a fibrinous exudate that may be found covering the graft. Any incisions from concomitant procedures should be opened and irrigated to avoid missing an extraarticular collection of fluid that could reseed the knee joint and lead to persistence of infection. Kohn26 described a case where the infection spread from the knee joint to the subcutaneous tissues of the operative wound and warned that in the presence of large surgical incisions, arthroscopic irrigation may spread purulent intraarticular material to adjacent

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extraarticular locations. Drains should be placed into the knee joint and in any incisions present; drains can be removed 48 hours later. Graft Retention Versus Removal Most authors have attempted to retain the graft in the initial management of septic arthritis after ACL surgery, but removal of the graft at a later time was necessary in some persistent cases.1–5,7,9 Williams et al1 removed acutely one of seven grafts because the graft appeared to be loose and nonfunctional. In three of the six knees with retained grafts, the infection persisted and a repeat procedure was performed; the graft was removed in another three cases, and, overall the graft was successfully salvaged in three of seven cases. Indelli et al4 attempted to retain all grafts; repeat procedures were needed in five of six patients and two grafts were subsequently removed, such that finally four of six grafts were retained. Other investigators were able to retain all implanted grafts.2,7 In contrast, Burks et al3 proposed an aggressive protocol that included graft removal at the initial irrigation and débridement procedure; the four patients in this series had no recurrence of infection, and all underwent repeat ACL reconstruction. In our opinion, preservation of the graft may be justified in acute postoperative infections that are diagnosed and treated without a delay. Graft removal during the initial procedure should be performed if the graft is loose and nonfunctional.1 Graft removal should be considered if there is a delay in presentation and an ongoing infection has been untreated for more than a few days, if the articular cartilage seems to be already affected, or if a virulent organism is present.4 Although unlikely, the presence of patient comorbidities is a factor in favor of graft removal because the defense mechanisms of the host may be compromised due to chronic disease. The type of graft is another consideration; allograft contamination has been reported, and surgeons are more prone to acutely remove an allograft compared with an autograft.10

Postoperative Management The physical therapy program should focus on preventing stiffness with passive and active-assisted range of motion exercises. Continuous passive motion can also be used. A hinge knee brace is applied, and toe-touch weight bearing is implemented until all wounds are clinically healed. Weight bearing then progresses as tolerated by the patient. Clinical and laboratory monitoring for control of infection and possible recurrence is necessary, especially if the graft has been retained. The threshold for a repeat irrigation and débridement should be very low if symptoms of knee pain, limitation of motion, and effusion recur in the postoperative period. 555

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Management of Persistent Cases Initial management with arthroscopic irrigation and débridement, graft preservation, and antibiotic therapy may not control the infection in all cases. The infection recurrence rate was 83% (5 of 6 cases) in the series by Indelli et al,4 50% (3 of 6 cases) in the series of Williams et al,1 and 29% (2 of 7 cases) in the series by Fong et al.7 McAllister et al2 reported that, despite the acute presentation of infections (8 to 18 days) and the immediate (within 24 hours) intervention, two to four repeat surgical procedures were necessary in each patient to control the infection and restore range of motion of the knee. Indelli et al4 have clearly established the goals of management in their manuscript; the first goal is to protect the articular cartilage, and the second goal is to protect the graft. The articular cartilage may undergo irreversible damage from an ongoing or inadequately treated infectious process, and currently options for restoring articular cartilage are very limited. Persistent septic arthritis following failure of the arthroscopic irrigation and débridement procedure with graft retention to control the infection is of particular concern; the infectious process has not been controlled by the initial procedure, the articular cartilage has been exposed to the detrimental effects of a persistent infectious process for a prolonged period of time, and the avascular graft and hardware provide substrate for biofilm formation,17 which may prevent eradication of infection. McAllister et al2 were able to retain the graft by managing persistent infections with two to four subsequent débridement procedures. However, degenerative changes developed in all four of their patients at a mean follow-up of 36 months, possibly because of the adverse effect of ongoing infection on articular cartilage. On the contrary, Burks et al3 reported that the four patients managed by graft removal and repeat ACL reconstruction in their series had no joint space narrowing at a mean follow-up of 21 months. Therefore persistent septic arthritis calls for a more aggressive approach to avoid articular cartilage damage and arthrofibrosis. Persistence of infection has been proposed as a reason for graft removal in the literature.1,3,4 However, a survey of directors of sports medicine fellowship programs showed no agreement regarding the fate of the graft and implanted hardware.10 In the event of a persistent infection unresponsive to the initial treatment, 36% of surgeons (22 of 61) would proceed with graft removal, whereas 64% would elect to retain the graft. The treating surgeon may be reluctant to remove the graft in persistent infections because the knee joint will be destabilized and a subsequent procedure will be necessary for repeat reconstruction of the ACL. However, there are unique advantages to this approach. First, the articular cartilage is protected from permanent damage, which would adversely affect the final outcome. Second, removal of the graft does

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not preclude ACL reconstruction at a later stage; the treating surgeon can employ alternative autograft or allograft techniques to address the unstable knee following removal of an infected graft, resulting in a satisfactory outcome.3 Third, although the additional procedure appears to be a drawback, it may actually decrease hospitalization time and overall cost because graft retention has been associated with repeat surgeries in order to control the infection.1,2,4,7 In the series by McAllister et al,2 two to four subsequent procedures were needed per patient and the mean hospital stay was 12.5 days. In contrast, Burks et al reported a total hospitalization time of 4 days for management of infection and repeat ACL reconstruction in patients managed with an aggressive protocol.3

Authors’ Protocol for Persistent Septic Arthritis of the Knee In our opinion, an aggressive approach offers the best chance of controlling inadequately treated, persistent infections following ACL reconstruction and should be strongly considered in such cases. Our protocol for persistent infections is based on radical débridement consisting of the following elements: open arthrotomy, complete synovectomy, graft removal, removal of any interference screws or other implants, and curettage and débridement of both the femoral and tibial tunnel.6 Aerobic, anaerobic, mycobacterial, and fungal cultures are obtained from multiple sources: joint fluid, synovium, graft, and bone (from the vicinity of both the femoral and the tibial tunnels). Organism-specific antibiotic therapy is given for 6 weeks. This protocol was used in five consecutive patients with persistent septic arthritis of the knee following arthroscopic ACL reconstruction.6 Patients had previously undergone one to three unsuccessful débridement procedures with recurrence of the infection and were referred to the senior author (M.J. Patzakis). The time elapsed from the initial diagnosis of infection to definitive management with radical débridement ranged from 11 days to 22 months. At a median follow-up time of 20 months (6 to 27 months), all patients were free from infection, but degenerative changes of the involved knee joint developed and one patient underwent total knee arthroplasty. Three of five infections were polymicrobial. Interestingly, in all three polymicrobial cases different organisms grew from the multiple tissue samples that included joint fluid, synovium, graft, and bone. It has been proposed that different organisms may be preferentially growing in isolated microenvironments,27 and a study on chronic osteomyelitis evaluating cultures from multiple sites showed that the same organisms grew on culture of the specimens from every site in only 47% (14 of 30) of patients.28 Therefore multiple cultures from different sources may help

Infections in Anterior Cruciate Ligament Surgery identify additional pathogens that otherwise may have been undetected. In persistent cases, the presence of an unusual organism may explain the poor response to therapy; aerobic, anaerobic, mycobacterial, and fungal cultures should be obtained, and tissue samples should be sent for pathology. Burke and Zych24 reported a case of persistent infection following ACL surgery that was diagnosed as mucormycosis approximately 7 months after the initial presentation, leading to osteomyelitis and destruction of the proximal tibia. It should be noted that cultures of bone specimens were positive in three of five persistent infections, indicating the presence of tunnel osteomyelitis. Graft removal allows for débridement of the femoral and tibial tunnels. This underscores the importance of aggressive management of the septic knee following ACL reconstruction once the initial attempt at graft retention has failed to control the infection.

ALLOGRAFTS AND INFECTIONS IN ANTERIOR CRUCIATE LIGAMENT SURGERY Reconstruction of the ACL with autograft tissue, BPTB, or hamstrings, has been well described in the literature.29–31 Alternatively, allograft tissue can be used to provide a source of graft material in revision cases, preserve the extensor or flexor mechanisms, and decrease the operative time; however, allograft structural properties may be compromised by sterilization and storage procedures, incorporation may be slow and incomplete, an immunological response may take place, the cost is increased, and an infection risk is present.29,32,33 Contaminated allografts may result in transmission of viral disease or bacterial infections from the donor to the recipient.

Viral Disease Viral disease, including human immunodeficiency virus (HIV) infection, hepatitis B, and hepatitis C, has been transmitted by transplantation of musculoskeletal allografts harvested from infected donors prior to implementation of a screening process.34 Therefore adherence to screening methods is critical to exclude grafts from infected individuals from being used. The Food and Drug Administration (FDA) initiated oversight of tissue banking in 1993 and requires that potential donors undergo a screening process that includes serologic tests for HIV-1, HIV-2, hepatitis B, and hepatitis C viruses.35 However, a time window exists from infection with one of these viruses to development of a detectable antibody response, and transmission of hepatitis B and C has been reported after allograft implantation for ACL reconstruction.36,37

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Bacterial Infections Implantation of contaminated allograft tissue has been reported as a source of unusual infections following ACL reconstruction and other knee procedures.32,38–42 The Centers for Disease Control and Prevention (CDC) in 2001 reported four cases of septic arthritis following ACL reconstruction associated with contaminated BPTB allografts; the report warned that when septic arthritis develops after allograft use, contamination of the allograft should be suspected.41 This is particularly important in polymicrobial, gram-negative, or anaerobic organism infections. Other reports included a patient who developed Clostridium sordellii septicemia and died within 1 week of receiving an osteochondral allograft,40,42 as well as a patient who developed an invasive Streptococcus pyogenes infection after ACL reconstruction with an allograft.38 As of March 2002, the CDC had identified 26 cases of bacterial infections associated with musculoskeletal allografts.39 Thirteen infections were caused by Clostridium species and 11 by gram-negative bacilli (5 were polymicrobial), and in two cases cultures were negative. Eighteen of these 26 infections (69%) occurred following allograft implantation for ACL reconstruction. Only 3 of 26 allografts (12%) were reported to have undergone gamma irradiation for sterilization. Crawford et al43 investigated an outbreak of infections following ACL reconstruction in one outpatient surgical center. The infection rate was 3.3% (11 of 331), and all infections occurred in the subgroup of patients in whom aseptically processed—but not sterilized—allografts were used. The infection rate in this subgroup was 4.4% (11 of 250) compared with 0% (0 of 41) in the autograft group and 0% in the sterilized allograft group. Gram-negative organisms were identified in 6 of 11 cases and Candida glabrata in 2 of 11 cases. These outbreaks of infections highlight the need for allograft sterilization. Aseptic processing and preservation of the graft without sterilization do not ensure patient safety because endogenous contamination of the allograft may exist at the time of harvesting.44,45 Deijkers et al44 evaluated the bacterial contamination of 1999 bone allografts retrieved from 200 cadaver donors under sterile operating conditions and reported that organisms of low pathogenicity (such as coagulase-negative staphylococci) were cultured from 50% of the allografts, whereas organisms of high pathogenicity (such as S. aureus, streptococcal species, Clostridium species, and Gramnegative organisms) were cultured from 3%. The authors described two mechanisms of contamination. Exogenous contamination, which was influenced by the procurement

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Anterior Cruciate Ligament Reconstruction team, was considered mainly responsible for organisms of low pathogenicity; endogenous contamination, which was influenced by the status of the donor, was considered the probable source of virulent organisms. The risk of contamination with organisms of high pathogenicity was 3.4 times higher in donors with a traumatic cause of death. Martinez et al45 reported that positive blood cultures were present in 8.6% of “beating heart cadaver” donors compared with 38% of postmortem donors. This increase may be attributed to the postmortem dissemination of endogenous bacteria (such as normal intestinal flora) secondary to loss of the intestinal barrier. Microorganisms were isolated from the bones of 59% (118 of 201) of donors who had negative blood cultures; thus blood cultures alone are not useful indicators of sterility of the tissues recovered for transplantation. Therefore, in addition to aseptic harvesting and processing, allograft tissue should undergo a sterilization process, such as ethylene oxide or gamma irradiation, to avoid transmission of infectious agents.46 However, concerns exist regarding the current processes; gamma irradiation may cause structural damage to the allograft,47,48 whereas ethylene oxide may penetrate tissue inadequately and cause inflammatory intraarticular reactions.49 New sterilization techniques are being developed with the aim of killing microorganisms and spores while at the same time preserving the biomechanical integrity of the processed tissues.46

INTRAOPERATIVE GRAFT CONTAMINATION Intraoperative contamination of the graft may occur by accidentally dropping the graft on the floor or by contacting the graft with a nonsterile object. A recent survey of 196 sports medicine fellowship directors showed that 49 of the responding surgeons (25%) had experienced contamination of 57 grafts; it occurred once in 43 surgeons (22%) and two to four times in six surgeons (3%).50 Another study reported that the graft was dropped on the operating room floor in four of 1038 ACL reconstruction cases, resulting in a 0.4% rate of accidental graft contamination.51 In this unfortunate event, the surgeon is faced with the dilemma of implanting a contaminated graft following a cleansing procedure or discarding the contaminated graft and employing an alternative one. Cleansing the graft carries the potential risk for septic arthritis. However, the alternatives are not without potential problems; use of an alternative autograft creates further morbidity for the patient, whereas an allograft increases the cost and may not be readily available. The survey by Izquierdo et al50 reported that cleansing of the graft is the most common practice; graft cleansing was used for 75% of contaminated grafts (43 of 57), whereas an alternative autograft was used 558

in 18% of cases (10 of 57) and an allograft in 7% (4 of 57). Solutions of chlorhexidine gluconate, antibiotics, povidone-iodine, or combinations thereof were used for cleansing of the graft, and none of the 43 decontaminated grafts was associated with a postoperative infection.50 Casalonga et al51 sequentially soaked four contaminated grafts in rifamycin and gentamicin solutions, and no infections occurred at a mean follow-up of 2 years. An in vitro study warned that soaking the graft for 15 minutes in an antibiotic solution (bacitracin and polymyxin B) will not sterilize the graft in 30% of cases (3 of 10).52 Another study found that soaking for 30 minutes in a 10% povidone-iodine or a triple-antibiotic solution (gentamicin, clindamycin, polymyxin) was not able to sterilize grafts contaminated with two different species of coagulase-negative staphylococci, whereas 4% chlorhexidine gluconate effectively decontaminated the grafts.53 The same study reported that when grafts were contaminated with five virulent organisms (S. aureus, Escherichia coli, P. aeruginosa, K. pneumoniae, and Enterococcus faecalis), 4% chlorhexidine gluconate was able to eliminate all organisms except K. pneumoniae. Using a triple-antibiotic solution after chlorhexidine gluconate eliminated this organism as well.53 Molina et al54 evaluated three antibacterial solutions for decontamination of ACL specimens harvested during total knee arthroplasty and dropped on the floor. Soaking in chlorhexidine gluconate solution for 90 seconds appeared to be the most effective with positive cultures in broth only in 1 of 50 specimens (2%). Grafts soaked in antibiotic solution of neomycin and polymyxin B had 3 of 50 specimens positive (15%), whereas grafts soaked in 10% povidone-iodine solution had 12 of 50 specimens positive (24%). Burd et al55 reported that power irrigation with a 2% chlorhexidine gluconate was effective in decontaminating grafts within 10 to 12 minutes, thus expediting the decontamination process. It should be noted that chlorhexidine may cause articular cartilage damage.56 Subsequent soaking in an antibiotic solution and rinsing of the graft prior to implantation may be beneficial if a chlorhexidine solution has been used.

References 1. Williams RJ III, Laurencin CT, Warren RF, et al. Septic arthritis after arthroscopic anterior cruciate ligament reconstruction. Diagnosis and management. Am J Sports Med 1997;25:261–267. 2. McAllister DR, Parker RD, Cooper AE, et al. Outcomes of postoperative septic arthritis after anterior cruciate ligament reconstruction. Am J Sports Med 1999;27:562–570. 3. Burks RT, Friederichs MG, Fink B, et al. Treatment of postoperative anterior cruciate ligament infections with graft removal and early reimplantation. Am J Sports Med 2003;31:414–418. 4. Indelli PF, Dillingham M, Fanton G, et al. Septic arthritis in postoperative anterior cruciate ligament reconstruction. Clin Orthop 2002;398:182–188.

Infections in Anterior Cruciate Ligament Surgery 5. Viola R, Marzano N, Vianello R. An unusual epidemic of Staphylococcusnegative infections involving anterior cruciate ligament reconstruction with salvage of the graft and function. Arthroscopy 2000;16:173–177. 6. Zalavras CG, Patzakis MJ, Tibone J, et al. Treatment of persistent infection after anterior cruciate ligament surgery. Clin Orthop Relat Res 2005;439:52–55. 7. Fong SY, Tan JL. Septic arthritis after arthroscopic anterior cruciate ligament reconstruction. Ann Acad Med Singapore 2004;33:228–234. 8. Musso AD, McCormack RG. Infection after ACL reconstruction: what happens when cultures are negative? Clin J Sport Med 2005;15:381–384. 9. Schollin-Borg M, Michaelsson K, Rahme H. Presentation, outcome, and cause of septic arthritis after anterior cruciate ligament reconstruction: a case control study. Arthroscopy 2003;19:941–947. 10. Matava MJ, Evans TA, Wright RW, et al. Septic arthritis of the knee following anterior cruciate ligament reconstruction: results of a survey of sports medicine fellowship directors. Arthroscopy 1998;14:717–725. 11. Cierny G, Mader JT, Pennick H. A clinical staging system for adult osteomyelitis. Contemp Orthop 1984;10:17–37. 12. Armstrong RW, Bolding F. Septic arthritis after arthroscopy: the contributing roles of intraarticular steroids and environmental factors. Am J Infect Control 1994;22:16–18. 13. Blevins FT, Salgado J, Wascher DC, et al. Septic arthritis following arthroscopic meniscus repair: a cluster of three cases. Arthroscopy 1999;15:35–40. 14. Hantes M, Basdekis G, Giotikas A, et al. Is there a potential for graft contamination during preparation for anterior cruciate ligament reconstruction? Presented at the European Bone and Joint Society Meeting, June, 2005, Lisbon, Portugal. 15. Diaz-de-Rada P, Barriga A, Barroso JL, et al. Positive culture in allograft ACL-reconstruction: what to do? Knee Surg Sports Traumatol Arthrosc 2003;11:219–222. 16. Hall-Stoodley L, Costerton JW, Stoodley P. Bacterial biofilms: from the natural environment to infectious diseases. Nat Rev Microbiol 2004;2:95–108. 17. Gristina AG, Costerton JW. Bacterial adherence and the glycocalyx and their role in musculoskeletal infection. Orthop Clin North Am 1984;15:517–535. 18. Gristina AG, Costerton JW. Bacterial adherence to biomaterials and tissue. The significance of its role in clinical sepsis. J Bone Joint Surg 1985;67A:264–273. 19. Patzakis MJ, Zalavras CG. Chronic posttraumatic osteomyelitis and infected nonunion of the tibia: current management concepts. J Am Acad Orthop Surg 2005;13:417–427. 20. Margheritini F, Camillieri G, Mancini L, et al. C-reactive protein and erythrocyte sedimentation rate changes following arthroscopically assisted anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:343–345. 21. Papakonstantinou O, Chung CB, Chanchairujira K, et al. Complications of anterior cruciate ligament reconstruction: MR imaging. Eur Radiol 2003;13:1106–1117. 22. Elsner HA, Dahmen GP, Laufs R, et al. Intra-articular empyema due to Staphylococcus caprae following arthroscopic cruciate ligament repair. J Infect 1998;37:66–67. 23. Vallianatos PG, Tilentzoglou AC, Koutsoukou AD. Septic arthritis caused by Erysipelothrix rhusiopathiae infection after arthroscopically assisted anterior cruciate ligament reconstruction. Arthroscopy 2003;19:E26. 24. Burke WV, Zych GA. Fungal infection following replacement of the anterior cruciate ligament: a case report. J Bone Joint Surg 2002;84A:449–453. 25. Campion J, Allum R. Necrotising fasciitis following anterior cruciate ligament reconstruction. A case report. Knee 2006;13:51–53. 26. Kohn D. Unsuccessful arthroscopic treatment of pyarthrosis following anterior cruciate ligament reconstruction. Arthroscopy 1988;4:287–289. 27. Marrie TJ, Costerton JW. Mode of growth of bacterial pathogens in chronic polymicrobial human osteomyelitis. J Clin Microbiol 1985;22:924–933.

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28. Patzakis MJ, Wilkins J, Kumar J, et al. Comparison of the results of bacterial cultures from multiple sites in chronic osteomyelitis of long bones. A prospective study. J Bone Joint Surg 1994;76A:664–666. 29. Beynnon BD, Johnson RJ, Abate JA, et al. Treatment of anterior cruciate ligament injuries, part I. Am J Sports Med 2005;33:1579–1602. 30. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146. 31. Laxdal G, Kartus J, Hansson L, et al. A prospective randomized comparison of bone-patellar tendon-bone and hamstring grafts for anterior cruciate ligament reconstruction. Arthroscopy 2005;21:34–42. 32. Barbour SA, King W. The safe and effective use of allograft tissue— an update. Am J Sports Med 2003;31:791–797. 33. Shelton WR, Treacy SH, Dukes AD, et al. Use of allografts in knee reconstruction: I. Basic science aspects and current status. J Am Acad Orthop Surg 1998;6:165–168. 34. Tomford WW. Transmission of disease through transplantation of musculoskeletal allografts. J Bone Joint Surg 1995;77A:1742–1754. 35. Human tissue intended for transplantation—FDA. Interim rule; opportunity for public comment. Fed Regist 1993;58–238:65514–65521. 36. Hepatitis C virus transmission from an antibody-negative organ and tissue donor–United States, 2000–2002. MMWR Morb Mortal Wkly Rep 2003;52–13:273–274,276. 37. Grafe M, Kurzweil P. Anterior cruciate ligament reconstruction with achilles tendon allografts in revisions and patients over 30. Presented at the Arthroscopy Association of North America Meeting, May, 2005, Vancouver, BC, Canada. 38. Invasive Streptococcus pyogenes after allograft implantation—Colorado, 2003. MMWR Morb Mortal Wkly Rep 2003;52–48:1174–1176. 39. Update: allograft-associated bacterial infections—United States, 2002. MMWR Morb Mortal Wkly Rep 2002;51–10:207–210. 40. Update: Unexplained deaths following knee surgery—Minnesota, 2001. MMWR Morb Mortal Wkly Rep 2001;50–48:1080. 41. Septic arthritis following anterior cruciate ligament reconstruction using tendon allografts—Florida and Louisiana, 2000. MMWR Morb Mortal Wkly Rep 2001;50–48:1081–1083. 42. Unexplained deaths following knee surgery—Minnesota, November 2001. MMWR Morb Mortal Wkly Rep 2001;50:1035–1036. 43. Crawford C, Kainer M, Jernigan D, et al. Investigation of postoperative allograft-associated infections in patients who underwent musculoskeletal allograft implantation. Clin Infect Dis 2005;41:195–200. 44. Deijkers RL, Bloem RM, Petit PL, et al. Contamination of bone allografts: analysis of incidence and predisposing factors. J Bone Joint Surg 1997;79B:161–166. 45. Martinez OV, Malinin TI, Valla PH, et al. Postmortem bacteriology of cadaver tissue donors: an evaluation of blood cultures as an index of tissue sterility. Diagn Microbiol Infect Dis 1985;3:193–200. 46. Vangsness CT Jr, Garcia IA, Mills CR, et al. Allograft transplantation in the knee: tissue regulation, procurement, processing, and sterilization. Am J Sports Med 2003;31:474–481. 47. Gibbons MJ, Butler DL, Grood ES, et al. Effects of gamma irradiation on the initial mechanical and material properties of goat bonepatellar tendon-bone allografts. J Orthop Res 1991;9:209–218. 48. Fideler BM, Vangsness CT Jr, Lu B, et al. Gamma irradiation: effects on biomechanical properties of human bone-patellar tendon-bone allografts. Am J Sports Med 1995;23:643–646. 49. Jackson DW, Windler GE, Simon TM. Intraarticular reaction associated with the use of freeze-dried, ethylene oxide-sterilized bone-patella tendon-bone allografts in the reconstruction of the anterior cruciate ligament. Am J Sports Med 1990;18:1–10. 50. Izquierdo R Jr, Cadet ER, Bauer R, et al. A survey of sports medicine specialists investigating the preferred management of contaminated anterior cruciate ligament grafts. Arthroscopy 2005;21:1348–1353. 51. Casalonga D, Ait Si Selmi T, Robinson A, et al. [Peroperative accidental contamination of bone-tendon-bone graft for the

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Anterior Cruciate Ligament Reconstruction reconstruction of the anterior cruciate ligament. Report of 4 cases]. Rev Chir Orthop Reparatrice Appar Mot 1999;85:740–743. 52. Cooper DE, Arnoczky SP, Warren RF. Contaminated patellar tendon grafts: incidence of positive cultures and efficacy of an antibiotic solution soak—an in vitro study. Arthroscopy 1991;7:272–274. 53. Goebel ME, Drez D Jr, Heck SB, et al. Contaminated rabbit patellar tendon grafts. In vivo analysis of disinfecting methods. Am J Sports Med 1994;22:387–391.

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54. Molina ME, Nonweiller DE, Evans JA, et al. Contaminated anterior cruciate ligament grafts: the efficacy of 3 sterilization agents. Arthroscopy 2000;16:373–378. 55. Burd T, Conroy BP, Meyer SC, et al. The effects of chlorhexidine irrigation solution on contaminated bone-tendon allografts. Am J Sports Med 2000;28:241–244. 56. van Huyssteen AL, Bracey DJ. Chlorhexidine and chondrolysis in the knee. J Bone Joint Surg 1999;81:995–996.

Allograft Complications and Risk Factors INTRODUCTION Allograft use has been increasing because donor site morbidity is avoided. Although this benefit is well understood, the drawbacks are more complicated and less well understood. The purpose of this chapter is to collect information on potential allograft risk and allograft complications to help surgeons in their risk-benefit analyses. Some of the information contained in this chapter can be found elsewhere in the chapters on stability results (see Chapter 69) and infections (see Chapter 70). Potential allograft complications/ risks can be divided into three categories: (1) graft failure or increased laxity and late graft laxity; (2) infection; and (3) disease transmission. The first two also occur with autografts; the third is allograft specific. Potential causes for increased allograft laxity are: (1) radiation sterilization; (2) nonradiation sterilization; (3) freezing; (4) increased donor age; and (5) increased allograft shelf life. Potential causes for increased allograft infection and disease transmission risk are: (1) failure to follow tissue-handling guidelines; (2) fraudulent procurement practices; (3) lack of sterilization; (4) foreign body effects; and (5) harvest/preparation contamination. These are summarized in Box 71-1. It is of interest to note that two of these factors involve human error by individuals not within the surgeon’s control. This highlights the inherently increased risk in allografts versus autografts attendant to the fact that so many delicate and exacting tasks must be properly performed before the graft gets to the operatingroom.

Most tissue banks are run meticulously and with great care. However, human error, or intentional human misbehavior, can occur with the surgeon unaware.

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Chadwick C. Prodromos Brian T. Joyce

AREAS OF MORBIDITY Graft Failure and Laxity The meta-analytic data presented in Chapter 69 showed allografts to have a failure rate two to three times that of autografts, even when radiated grafts were removed from consideration. It also showed the allograft normal stability rate to be significantly lower. This effect occurred in both bone–patellar tendon–bone (BPTB) and soft tissue grafts. This material is covered in more detail in that chapter. Despite these overall worse stability results, it should be pointed out that some reports show excellent allograft stability rates.1

Delayed Graft Failure There is some evidence that allografts have a tendency toward late failure,2–4 whereas autografts have shown very little tendency to late failure.5 This perhaps mirrors the experience with bone allografts, which can fracture years after clinical implantation. This late failure has been accompanied by biopsy evidence of late or absent recellularization,2,3,6 which may be causally related. It may be that allograftimplanted patients should be counseled that late 561

Anterior Cruciate Ligament Reconstruction BOX 71-1 Allograft Complications Areas of Potential Allograft Morbidity Graft failure/laxity Late graft failure Infection Disease transmission Potential Causes of Laxity/Failure Radiation sterilization Chemical treatments Freezing Increased donor age Increased graft shelf time Immunological response to graft Risk Factors for Infection/Disease Transmission Human error Human fraudulent behavior Lack of sterilization Foreign body effects Contamination

failure can occur. A longer period of follow-up for allograft patients may be indicated than is necessary with autografts.

Infection It is not clear whether the overall infection rate is higher for allografts than for autografts, but there is evidence that it may be so. The Centers for Disease Control and Prevention (CDC), in a well-known analysis of one surgicenter’s experience, showed no infections in autografts and sterilized allografts but a 3% infection rate7 in unsterilized allografts. In our clinical experience the only infected anterior cruciate ligament reconstruction (ACLR) failures we have seen have been in allografts. We have seen one patient with two infected allografts from two different tissue banks operated at two different hospitals by different surgeons for each procedure. This patient went on to autograft revision without incident.

Disease Transmission The rate of disease transmission risk is difficult to evaluate because routine viral testing of post-allograft patients is not carried out, although it is certainly very low. A recent report, however, included a patient who had hepatitis B transmitted from a donor who initially tested negative for hepatitis B and whose allograft was radiated. After the recipient contracted hepatitis, repeated, more sophisticated testing showed that that the donor was indeed the source of the hepatitis virus.8 Studies would indicate that the current sub–3Mrad levels of radiation now most often employed would be expected to kill neither the hepatitis nor human immunodeficiency viruses.9,10 Higher levels in the 5Mrad range are probably necessary. Newer

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protocols using such higher doses with radioprotectant may provide the answer.11

POTENTIAL CAUSES OF INCREASED LAXITY Radiation Sterilization Radiation has been clearly shown to weaken grafts.12–20 Newer protocols are intended to mitigate or eliminate this effect, but 2-year follow-up data are currently lacking.

Chemical Treatments Non-radiation cleaning (e.g., Allowash, Lifenet, Virginia Beach, VA), sterilization (e.g., Biocleanse, Lifenet),21 cryoprotectant,22 radioprotectant (e.g., Clearant, Los Angeles, CA), tutoplasty, ethylene oxide, and other techniques are used on allografts. The more aggressive these procedures, the more they affect the material properties of the graft. In one recent study the mechanical properties of the grafts were substantially altered by a cryoprotectant technique such that the surgeon was unable to use the graft.22 Questions about these grafts can only partially be answered by studies that analyze strength at time zero. It is the response of the graft to cellular and vascular ingrowth and ligamentization that determines ultimate strength. The effects of such treatments on this process have been little studied.

Freezing Most grafts are frozen and rethawed at least twice. Grafts are initially frozen after procurement pending the results of cultures. Typically they are then thawed and prepared and then refrozen while a recipient is identified. Freezing has been shown to adversely affect tissue properties.23 Cryoprotectants are used to protect grafts from the deleterious effects of freezing, but it is unknown how well they work. The temperature of freezing also plays a role. Thus it is reasonable to wonder how much a single cycle of freezing may alter the graft or the subsequent ligamentization remodeling process. Further complicating this issue is the fact that some grafts are only frozen, whereas some are freeze-dried or lyophilized. It is unknown whether the addition of drying to freezing is a benefit because it removes potentially damaging ice crystals, is of no consequence, or is deleterious because it further modifies the tissue.

Increased Donor Age Kurzweil8 found a strong trend toward greater laxity with increased donor age in patients undergoing tendo–Achilles ACLR. Criteria for donor age vary widely, and no standard criteria exist for upper age limit.

Allograft Complications and Risk Factors

Increased Shelf Time

Contamination

A correlation between laxity after ACLR and the time the graft spent on the shelf prior to use was found in one study.24 This parameter is generally not monitored and needs further study.

Even with the best technique, the extensive handling of the graft necessary for procurement and preparation increases the chances of graft contamination

Immunological Response It has been shown that allografts generate an increased immunological response relative to autografts.25,26 It may be that this response inhibits ligamentization and cellular repopulation, leading to graft laxity or failure.

POTENTIAL CAUSES OF INFECTION AND DISEASE TRANSMISSION Failure to Follow Tissue-Handling Procedures Examples include one death and several infections that occurred in 2001 as a result of failure to follow established procedures from one leading tissue bank. Another was a Food and Drug Administration (FDA) recall in December 2004 of several knee allografts due to the tissue having been “incorrectly tested for viral markers” from another leading tissue bank. Thus although tissue banks pay extraordinary attention to quality control, human error can still occur.

Fraudulent Tissue Procurement of Unsuitable Tissue Dubbed the “Frankenstein” or “body snatching” scandal by the media, this highly publicized 2005 episode involved procurement of nonsterile, aged, and often diseased body parts from funeral homes that were then represented as having been taken under sterile conditions from hospitals. A significant number of ACL grafts were implanted. Debates and lawsuits are now in process over what complications are attributable to these grafts. With government inspections having fallen from one in three tissue companies annually in 2001 to one in eight in 2006 as the number of companies has increased from 406 to 2030,27 the possibility of undetected problems is very real. The surgeon must thus be familiar not only with the tissue bank but also with its graft feeder sources.

Lack of Sterilization It is believed by many (see Chapter 70) that sterile procurement by itself is inadequate to guard against disease transmission.

Foreign Body Effects The allograft is a foreign body and as such is predisposed to infection relative to host tissue.

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CONCLUSIONS 1 Overall allografts have been found to have a higher failure rate, greater laxity, and perhaps a higher late failure rate than autografts. The reasons are not clearly understood. 2 It appears that allografts may have a higher infection rate than autografts, although the overall rate is low. 3 Disease transmission is a risk present in allografts but not autografts. The risk is very low but unquantified. 4 The effects of freezing, cryoprotection, drying, radiation, radioprotection, chemical cleaning, and chemical sterilization on the material properties of the graft after ligamentization and on the ability of the graft to be adequately revascularized and repopulated with cells are unknown. Extensive study is needed. Time-zero mechanical studies are not adequate to predict ultimate viability and strength of allografts. 5 Graft preparation and procurement are not within the surgeon’s direct control. Human error and fraudulent behavior have led to severe complications. Surgeons should familiarize themselves with the tissue bank(s) they wish to use, as well as their graft sources, and become familiar with the banks’ policies and procedures. 6 Nonsterilized grafts may pose a risk of disease transmission. However, graft sterilization techniques may adversely affect the material properties of the grafts. Radioprotectant and higher-dose radiation may provide an answer pending ongoing studies.

References 1. Bach BR Jr, Aadalen KJ, Dennis MG, et al. Primary anterior cruciate ligament reconstruction using fresh-frozen, nonirradiated patellar tendon allograft: minimum 2-yeasr follow-up. Am J Sports Med 2005;33:284–292. 2. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue ACL reconstruction. Presented at symposium at the 2006 meeting of the American Academy of Orthopaedic Surgeons, Chicago, March, 2006. 3. Siegel MG. Personal communication, May, 2006. 4. Risinger RJ, Bach BR Jr. Late anterior cruciate ligament reconstruction failure by femoral bone plug dislodgement. J Knee Surg 2006;19:202–205.

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Anterior Cruciate Ligament Reconstruction 5. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 6. Scheffler S, Unterhauser F, Keil J, et al. Comparison of tendon-to-bone healing after soft tissue autograft and allograft ACL reconstruction in a sheep model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Austria, May, 2006. 7. Crawford C, Kainer M, Jernigan D, et al. Investigation of postoperative allograft-associated infections in patients who underwent musculoskeletal allograft implantation. Clin Infect Dis 2005;41:195–200. 8. Grafe MW, Kurzweil PR. ACL reconstruction with Achilles tendon allografts in revisions and patients over 30. Presented at the 2005 meeting of the Arthroscopy Association of North America, Vancouver, BC, Canada, May, 2005. 9. Fideler BM, Vangsness CT Jr, Moore T, et al. Effects of gamma irradiation on the human immunodeficiency virus. J Bone Joint Surg 1994;76A:1032–1035. 10. Tomford WW. Transmission of disease through transplantation of musculoskeletal allografts. J Bone Joint Surg 1995;77A:1742–1754. 11. Forng RY, Willkommen H, Almeida J, et al. Terminal sterilization of human tissue allografts: application of high-dose gamma irradiation using the clearant process. Unpublished data. 12. Smith CW, Young IS, Kearney JN. Mechanical properties of tendons: changes with sterilization and preservation. J Biomed Eng 1996;118:56–61. 13. Maeda A, Inoue M, Shino K, et al. Effects of solvent preservation with or without gamma irradiation on the material properties of canine tendon allografts. J Orthop Res 1993;11:181–189. 14. Maeda A, Horibe S, Matsumoto N, et al. Solvent-dried and gammairradiated tendon allografts in rats. J Bone Joint Surg 1998;80B:731–736. 15. Goertzen MJ, Clahsen H, Burrig KR, et al. Sterilisation of canine anterior cruciate allografts by gamma irradiation in argon. J Bone Joint Surg 1995;77B:205–212. 16. Curran AR, Adams DJ, Gill JL, et al. The biomechanical effects of low-dose irradiation on bone-patellar tendon-bone allografts. Am J Sports Med 2004;32:1131–1135.

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17. Gibbons MJ, Butler DL, Grood ES, et al. Effects of gamma irradiation on the initial mechanical and material properties of goat bone-patellar tendon-bone allografts. J Orthop Res 1991;9:209–218. 18. Salehpour A, Butler DL, Proch FS, et al. Dose-dependent response of gamma irradiation on mechanical properties and related biochemical composition of goat bone-patellar tendon-bone allografts. J Orthop Res 1995;13:898–906. 19. Toritsuka Y, Shino K, Horibe S, et al. Effect of freeze-drying or gamma irradiation on remodeling of tendon allograft in a rat model. J Orthop Res 1997;15:294–300. 20. Hamer AJ, Stockley I, Elson RA. Changes in allograft bone irradiated at different temperatures. J Bone Joint Surg 1999;81B:342–344. 21. Mroz TE, Lin EL, Summit MC, et al. Biomechanical analysis of allograft bone treated with a novel sterilization process. Spine J 2006;6:34–39. 22. Caborn D, Nyland J, Chang HC, et al. Tendon allograft cryoprotectant incubation and rehydration time alters mechanical stiffness properties. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Austria, May, 2006. 23. Clavert P, Kempf JF, Bonnomet F, et al. Effects of freezing/thawing on the biomechanical properties of human tendons. Surg Radiol Anat 2001;23:259–262. 24. Sterling JC, Meyers MC, Calvo RD. Allograft failure in cruciate ligament reconstruction: follow-up evaluation of eighteen patients. Am J Sports Med 1995;23:173–178. 25. Arnoczky SP, Warren RF, Ashlock MA. Replacement of the anterior cruciate ligament using a patellar tendon allograft: an experimental study. J Bone Joint Surg 1986;68:376–385. 26. Schulte K, Thompson W, Jamison J, et al. The immune response to allograft anterior cruciate ligament reconstruction: clinical correlation. Presented at the 1996 meeting of the American Academy of Orthopaedic Surgeons, February 1996, Atlanta. 27. Hays T. Profit began before the grave in Frankenstein case. Chicago Sun Times, June 12, 2006, p 27. Available online at www.suntimes. com/output/news/cst-nws-flesh12.html.

Stiffness: Prevention and Treatment Anterior cruciate ligament (ACL) reconstruction has evolved into a highly successful procedure, with recent studies reporting good outcomes in more than 90% of the patients.1–3 Although the patellar tendon continues to be the most popular type of graft in North America, the quadruple hamstrings graft is emerging as the “other gold standard.” Multiple comparison studies document no difference in the outcomes between the two types of graft.4–6 Perhaps the two main reasons for the equal success rates are advances in the fixation methods of tendon grafts as well as an increase in our understanding of the biology of healing of ACL grafts. However, complications following ACL reconstruction do occur, and motion loss is one of the most common. The reported incidence is between 2% and 11%,7,8 and its management can be quite frustrating for both the patient and the surgeon. In this chapter we will discuss factors that are associated with development of arthrofibrosis after ACL reconstruction, propose strategies to avoid this complication, and present treatment options.

ETIOLOGY Genetic Predisposition The tendency of certain patients to develop excessive scarring following trauma or surgery is well known. A history of arthrofibrosis from previous surgery or trauma should alert the surgeon. The exact reason behind this excessive connective tissue proliferation is not known.

Several mechanisms have been proposed. Two cytokines, the platelet-derived growth factor-ß (PDGF-ß) and the transforming growth factor-ß (TGF-ß), have a central role in the healing process. Over-expression of TGF-ß has been associated with unresolved inflammation and fibrotic events.9 In animal models, neutralization of its isoforms (TGF-ß-1 and TGF-ß2) has reduced scarring.10 Interestingly, exogenous addition of the isoform TGF-ß-3 achieved the same effect. More recently, a possible association between arthrofibrosis and certain human leukocyte antigen (HLA) types has been suggested. Skutek et al11 performed HLA typing in a pool of patients who developed primary arthrofibrosis following ACL reconstruction. Patients with secondary reasons for arthrofibrosis, such as prolonged immobilization, infection, or other surgical complications, were excluded. In their patient group, the phenotype HLACw*08 was detected significantly more often compared with the control group. Additionally, in the same group of patients the phenotypes HLA-Cw*07 and HLA-DQB1 were detected significantly less frequently compared with the control group. The importance of the fat pad in the fibrotic process following surgical trauma to the knee has long been recognized.12 Adipose tissue is capable of releasing cytokines in an endocrine, autocrine, and paracrine manner.13 Ushiyama et al14 demonstrated that the infrapatellar fat pad produces a variety of growth factors and pro-inflammatory cytokines such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), tumor

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Anterior Cruciate Ligament Reconstruction necrosis factor alpha (TNF-a) and interleukin (IL)-6, much like an endocrine organ. Additionally, Murakami et al15 found elevated concentrations of PDGF-ß and TGF-ß in the fat pad after ACL reconstruction. From this research, it is evident that the knee fat pad is capable of mounting a response much like the articular synovium and enhances the inflammatory reaction to the surgical insult. Preservation and minimal disturbance of this structure during ACL reconstruction may minimize excessive scarring and motion loss.

Surgical Factors The timing of surgery following acute ACL tear and its association with motion loss have been the subject of many studies and an issue of controversy. Although some authors believe that early reconstruction (i.e., within 2 weeks from the injury) does not affect the ultimate knee range of motion (ROM) that the patient achieves,16–18 it seems that the majority of surgeons favor a delay varying from 1 to 3 weeks to allow resolution of the acute inflammation and restoration of ROM.7,19–21 Furthermore, even in studies where no motion complications were documented after early intervention, no advantage in terms of the outcome of the reconstruction was identified. Shelbourne et al22 found that patients who had delayed ACL reconstruction at a mean of 40 days after injury had earlier return of quadriceps strength and were able to progress to sport-specific rehabilitation sooner than patients who had their knee reconstructed early at a mean of 11 days after injury. It must be realized, however, that significant variability exists among patients in the intensity of the observed inflammation following acute ACL tear, and this is at least partially related to the energy of injury. Rather than relying on timetables or strictly followed protocols, we believe that the decision on surgical timing should be based on clinical observation of subsidence of the posttraumatic inflammation, restoration of ROM, and normalization of gait. The patient is advised to follow a classic RICE (rest, ice, compression, and elevation) regimen and is referred to physical therapy (i.e., prehab). This allows the patient to become familiar with the physical therapist and the exercises and equipment that will be used after the surgery, become emotionally prepared, and make other necessary arrangements for the upcoming surgery. These are all factors that contribute to correct patient education and, in our opinion, enhance compliance and chances for a successful outcome. The issue of timing becomes even more important when the ACL tear is combined with other ligament injuries. Associated medial collateral ligament (MCL) injury has been recognized as a combination that is particularly prone to loss of motion. The location of the MCL tear influences the return of motion, and patients with proximal (above the joint 566

line) injury are more likely to experience motion loss postoperatively.23 Low-grade injuries are successfully treated with an initial period of functional bracing to allow healing of the MCL. This waiting period is used to prehab the knee before the ACL reconstruction. In cases of associated severe grade III MCL or multi-ligamentous injury, priority is generally given to early restoration of knee stability. Attention during surgery is given to anatomical repair of the MCL, especially in injuries where the ligament is avulsed from its tibial attachment. Fixation of the superficial MCL near the joint line will prevent the normal posterior displacement of the ligament during knee flexion and will result in postoperative loss of flexion. Generally, in cases of multi-ligament reconstruction, slow return of motion should be anticipated and treated aggressively in the postoperative period. Graft malpositioning due to nonanatomical tunnel placement either in the tibia or the femur is one of the most common errors in the surgical technique of ACL reconstruction and is believed to be responsible for a high percentage of graft failures. Noyes and Barber-Westin24 reviewed a series of 114 consecutive ACL revisions and found that 30% involved cases of improper graft placement. Errant tunnel placement subjects the graft to excessive strains and, depending on its stiffness, can lead either to loss of motion or plastic deformation and elongation of the graft. The normal ACL has a complex anatomy, which the current, essentially cylindrical grafts are unable to reproduce. In theory, during reconstruction, an attempt is made to place the graft in an isometric position and at the same time avoid impingement of the graft on the surrounding anatomical structures. Hefzy et al25 found that of the two fixation points of the graft, the one that most affects graft isometry is the femoral. They identified a zone near the center of the femoral insertion of the normal ACL that was the most isometric, as defined by a length change of 2 mm or less. The axis of this zone has a nearly vertical orientation with the knee extended. Its width varies from 3 to 5 mm and tapers from proximal to distal. Anterior placement of the femoral tunnel was one of the most common errors during ACL reconstruction. Placing the graft too far anteriorly results in a graft that is lax in extension and tight in flexion. Often the end result is a joint with limited postoperative flexion. Attempts to regain full flexion in such a knee, as during postoperative rehabilitation, will subject the graft to excessive strains and compromise its integrity. Recognizing the problems associated with anterior femoral tunnel placement, some surgeons use the over-the-top position. Attachment of the graft in the over-the-top position essentially reverses the situation and results in a graft that is tight in extension but lax in flexion. Currently most surgeons prefer to place the entrance of the femoral tunnel high in the notch at the 10- or 2–o’clock position, at the proximal end of the zone described by Hefzy et al,25 where this zone is wider. Depending on the graft choice, a 1- to 2-mm back wall

Stiffness: Prevention and Treatment is left to allow safe fixation of the graft. We use three methods to identify the center of the femoral tunnel and place the femoral guide pin. This point may be selected using freehand technique, femoral over-the-top offset guides, and (less frequently) an isometer. Clear visualization of the over-the-top position is important with every method to avoid errors. When the surgeon uses a transtibial technique to drill the femoral tunnel, the orientation of the tibial tunnel dictates to a great extent the position of the femoral guide pin, especially when it is inserted through an offset guide. Correct placement of the tibial tunnel in the coronal and sagittal plane is important to avoid either anterior placement of the femoral pin or penetration of the back wall of the femur. In cases of suboptimal tibial tunnel placement, where the tendency of the guide pin is to point anteriorly, we have found it helpful to use a freehand technique and start the insertion of the femoral guide pin and subsequent drilling with the knee somewhat more extended (60 to 70 degrees) and complete the process with the knee flexed to 90 degrees or even more. This maneuver helps us to achieve posterior placement of the femoral tunnel and avoid penetration of the posterior wall. Other options are to convert to a two-incision technique and drill the femoral tunnel independent of the tibial tunnel or drill the femoral tunnel through the anteromedial arthroscopic portal. In the study of Hefzy et al,25 altering the tibial attachment site had a smaller effect on isometry of the graft. Nevertheless, the tibial attachment site is important if one is to avoid impingement of the graft on the intercondylar roof or the posterior cruciate ligament (PCL). Sapega et al26 noted that even in the normal ACL, only a few fibers are truly isometric (length change of 1 mm or less) over the full ROM of the knee. In their cadaveric study the fibers of the anteromedial bundle of the ACL demonstrated the least deviation from isometry. Many authors27–30 shared the same view and placed the tibial tunnel in the anteromedial footprint of the tibial ACL insertion in an attempt to re-create these fibers. However, anterior placement of the tibial tunnel anterior to an imaginary line and tangential to the intercondylar roof (Blumensaat’s line) with the knee in full extension results in roof impingement of the graft and loss of extension. Howell and Taylor31 found poor results in patients with impinged grafts in terms of extension loss and graft failure. They reported a 100% failure rate in the severely impinged grafts where the entire articular opening of the tibial tunnel was anterior to the slope of the intercondylar roof. The tibial insertion of the native ACL has an eccentric anterior extension32 that cannot be re-created without impingement of the graft in the intercondylar roof. Jackson and Schaefer33 reported a series of patients who presented with loss of extension following ACL reconstruction with patellar tendon autograft. Second-look arthroscopy revealed the presence of a fibrous

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nodule, reminiscent of a “cyclops,” in front of the ACL graft, which blocked extension. Excision of the nodule resulted in improvement of knee extension in all patients. Marzo et al34 described the same pathology in a group of patients following ACL reconstruction with patellar tendon or hamstring autograft. In both instances it was believed that the fibrous nodule was the result of anterior tibial tunnel placement and impingement of the graft in the intercondylar roof. Romano et al35 studied the effect of tibial tunnel placement on ROM. They found that placement of a portion of the tunnel medial to the medial tibial spine was associated with loss of flexion. Interestingly, in the same study, it was found that anterior placement of the tunnel was associated with loss of both extension and flexion. Lateral placement of the tibial tunnel can cause attrition of the graft on the lateral wall of the intercondylar notch and recurrent synovitis.36 A very posterior positioning of the tunnel in the tibia should be avoided because it is the least isometric and can cause excessive graft tension in extension, thus risking flexion contracture. Another cause of postoperative loss of flexion may be impingement of the graft on the PCL. This is determined by the angle of the tibial tunnel in the coronal plane. A tibial tunnel with an angle greater than 75 degrees with respect to the medial joint line will place the femoral tunnel close to the 12-o’clock position and cause impingement of the ACL graft on the PCL during knee flexion.37 Among the different landmarks that can guide tibial tunnel placement (i.e., medial tibial eminence, the PCL, the “over-the-back” position, the true posterior border of the tibia, and the posterior border of the anterior horn of the lateral meniscus), it appears that the PCL is the most reproducible.38 In an attempt to ameliorate errors in tunnel placement, avoid roof impingement of the graft, and account for individual anatomy, Howell39 introduced the one-step tibial guide that allows the surgeon to customize the sagittal and coronal position of the tibial tunnel to the specific combination of roof angle and extension (or hyperextension) in the reconstructed knee. Other options that may help correct placement of the tunnels and avoidance of roof impingement are the use of impingement rods or intraoperative fluoroscopy. It is our opinion that there is no foolproof method and the surgeon should use a combination of all of these methods to avoid nonanatomical graft placement and postoperative motion loss. Tensioning of the graft is another area that deserves special attention to prevent motion loss following ACL reconstruction. The optimal force for graft tensioning as well as the angle of knee flexion that such force should be applied are unknown. Clinically, the risk of undertensioning the graft and therefore not correcting the posttraumatic laxity should be balanced with the risk of overconstraining the knee. It has been suggested that the magnitude of tension should be graft specific and that hamstring grafts need higher initial 567

Anterior Cruciate Ligament Reconstruction tension.40 However, the surgeon has to keep in mind that an equally tensioned four-strand hamstring tendon graft has higher stiffness than a 10-mm bone–patellar tendon–bone (BPTB) graft.41 As the stiffness of new fixation devices for tendon grafts continues to improve, the risk of capturing the knee by overtensioning the quadruple hamstrings graft is very real. In a prospective clinical randomized study, Heis and Paulos42 compared laxity and flexion results using initial graft tensions of 68N and 88N. At the latest follow-up, the average side-to-side laxity measured 1.7 mm in the 68N group and 2.8 mm in the 88N group. Flexion angles at 4 weeks showed statistically significant difference between the two groups with average flexion of 109 degrees in the 68N and 88 degrees in the 88N group. In terms of overconstraining the knee, the flexion angle at which the tension is applied may have a greater impact than the applied force itself. Bylski-Austrow et al43 noted greater increases in force applied to the graft and greater posterior shifts in tibial position by changing the flexion angle at tensioning from 0 to 30 degrees than by increasing the initial tension from 22N to 44N. From a practical standpoint, in order to avoid motion loss postoperatively, we prefer to tension the graft at 20 to 30 degrees of flexion and neutral rotation with 12 to 15 pounds of tension unless the graft shortens more than 3 mm or more than 10% of its length between the two fixation points when the knee is brought into full extension. If such shortening is observed, tensioning is performed in extension.

Infrapatellar Contracture Syndrome Infrapatellar contracture syndrome represents an abnormal fibrosclerotic healing response through the anterior retinaculum, patellomeniscal ligaments, and fat pad tissues, which entraps the patella and leads to loss of extension and flexion of the knee and, in advanced stages, to patella baja and patellofemoral arthrosis. The syndrome can develop after knee injury or surgery but more often is seen after ACL reconstruction due to errors in the surgical technique or rehabilitation.12 The syndrome has three stages each, with distinctive characteristics. In stage I (2–8 weeks) the patient presents with periarticular inflammation and edema, immobility of the knee, and quadriceps weakness and lag. Later, in stage II (weeks 6–20), the knee demonstrates limited patellar mobility and an inferior tilt of the patella (shelf sign), and the quadriceps lag “disappears” but the patient ambulates with a bent knee gait. In stage III, generally from the eighth month onward, patellar mobility is somewhat improved but the knee develops patella baja and degenerative changes in the patellofemoral joint. The fat pad appears to have a central role in the pathogenesis of this syndrome; therefore every effort should be made to disturb this structure as little as possible during ACL 568

reconstruction. Early recognition of this process and avoidance of forced motion are extremely important so as not to further propagate inflammation and fibrosis.

Rehabilitation A well-delineated rehabilitation program is critical to avoid motion complications following ACL reconstruction. It has long been recognized that prolonged immobilization adversely affects the results of the procedure and increases the risk of arthrofibrosis.44 Immobilization of the knee in flexion after surgery has been abandoned, and today the operated knee is braced in extension. This practice has reduced the incidence of postoperative knee flexion contracture. Accelerated rehabilitation programs are in widespread use and have minimized motion complications. However, a common error is a strict adherence to timetables, which at times can be counterproductive and have the opposite from the desired effect. We use a “criteria-based rehabilitation protocol” that respects the individual response to the surgical insult and the ensuing healing process. The patient is advanced through the various phases of the rehabilitative protocol when certain criteria have been met and the knee is physiologically ready. The initial phase of this program focuses on reversal of the physiological imbalance of the knee. The main goals early are to decrease the postoperative swelling and pain (RICE), reverse the muscular inhibition of the quadriceps (electrical stimulation, biofeedback), preserve patellar mobility (glides and tilts), achieve early unassisted ambulation, and restore knee motion with emphasis in extension (quadriceps isometric sets; slow, nonmanual passive range of motion exercises; opposite-leg active assisted knee extension exercises). Once the patient has knee flexion of at least 110 degrees, is able to perform straight leg raises with no quad lag, has full passive knee extension, has minimal swelling and pain, and has good or improving patellar mobility, he or she can be advanced to the next phase(s), where the focus is shifted to strengthening and progressive neuromuscular challenging of the knee. It is important that these therapeutic interventions are nonpainful and do not further inflame the knee. Failure to recognize such responses can lead to patellar entrapment and arthrofibrosis. Close follow-up of the patient in the early postoperative period and good communication with the physical therapist are important for early detection of motion complications, which in the majority of cases can resolve easily with appropriate intervention and avoidance of forceful and painful range of motion exercises.

Other Causes Another, less common cause of postoperative stiffness is reflex sympathetic dystrophy (RSD) or complex regional

Stiffness: Prevention and Treatment pain syndrome. It represents an exaggerated sympathetic response after trauma or surgery. Clinical manifestations include pain out of proportion after injury or surgery, decreased skin temperature and mottling, hypersensitivity to touch, atrophic skin changes, osteopenia, and restricted ROM. The syndrome has been divided in three stages, and the best treatment is prevention. Preemptive analgesia in the form of local anesthetics and preoperative administration of nonsteroidal antiinflammatory medications and/or opioids can help decrease the incidence of this complication. The theoretical basis of preemptive analgesia is that it blocks nociceptive inputs generated during surgery that can trigger a state of hyperexcitability in the central nervous system. We routinely preinject the knee before the procedure with a solution of bupivacaine (Marcaine) and morphine. Poehling et al,45 in a study of patients with clinically significant RSD, found evidence of injury to the infrapatellar branch of the saphenous nerve in all of the patients. The saphenous nerve may give multiple infrapatellar branches that frequently cross over extensively into the lateral side of the knee and upper leg. Incisional neuromas of these branches after ACL reconstruction have received little attention in the literature but can be a source of significant morbidity extending beyond numbness or dysesthesia. Injury to the infrapatellar branch or the saphenous nerve itself may happen at various stages of the reconstructive procedure, such as during the superficial dissection, semitendinosus or gracilis tendon harvesting, and medial meniscus repair. Another cause of soft tissue irritation and restricted motion after ACL reconstruction is protruding hardware. Suspension devices used for femoral fixation of tendon grafts in the femur have been reported as a source of postoperative arthrofibrosis.46 The surgeon must ensure adequate seating within the bone of such implants.

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operative records and obtain orthogonal x-rays of the knee with the joint in extension to evaluate tunnel placement and hardware position. Occasionally, a knee magnetic resonance image (MRI) may give further insight. It allows evaluation of the graft and its position as well as the fat pad. An impinged graft will demonstrate increased signal in the distal two-thirds and deflection under the roof.48 In cases of suspected “Cyclops” lesion, an MRI is the study of choice (Fig. 72-1). The images should be scrutinized for other missed pathology, such as meniscal tears, failed meniscal repairs, and so on, that can hinder knee motion. Other laboratory workup such as complete blood count with differential, erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) knee aspiration, and synovial fluid analysis and cultures may be indicated in cases of suspected infection. The patient is approached initially using the same criteria-based rehabilitation program that we routinely use after ACL reconstruction. A return to an earlier phase of rehabilitation—and in the majority of cases, this is usually the first phase—is necessary in order to reverse the inflammation and physiological imbalance of the joint. The knee joint should have adequate time for rest, and therefore physical therapy sessions are scheduled every other day. Occasionally, for the same reason it may be necessary to cease physical therapy altogether. Emphasis is placed in reversing the

TREATMENT Whether motion loss following ACL reconstruction is due to genetic predisposition, errors in surgical timing or technique, the expression of a developing infrapatellar contracture syndrome, or merely the result of lack of appropriate rehabilitation, early recognition of this complication is crucial. It is our experience as well as that of others47 that early treatment yields better results. The clinical presentation is nearly identical in every case: an inappropriately painful and swollen knee, with significant periarticular inflammation, quadriceps inhibition and lag, inability to gain extension, limited passive patellar mobility, and failure to make progress during rehabilitation. In most cases, a careful history and physical examination focused on the previously discussed factors can point to the cause of the postoperative stiffness. It is useful to review

FIG. 72-1 In cases of suspected “Cyclops” lesion, magnetic resonance imaging (MRI) is the study of choice.

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Anterior Cruciate Ligament Reconstruction quadriceps inhibition with active ROM exercises, oppositeleg active assisted knee extension exercises, and liberal use of modalities such as electrical stimulation, biofeedback, and so on. Patellar mobility is maintained with passive mobilization exercises such as tilts and glides in the nonpainful range. It is much more important in this early stage to preserve and regain extension rather than flexion because loss of extension is poorly tolerated. Any forceful manipulation is strictly contraindicated, and the patient as well as the therapist should specifically be educated on this issue. Pharmacological management includes use of nonsteroidal antiinflammatory medications and, in more resistant cases, a brief course (1 to 2 weeks) of a tapered dose of methylprednisolone followed by indomethacin. In our experience, this has no deleterious effects on the healing graft and greatly facilitates physical therapy efforts. Manipulation under anesthesia is most successful to restore flexion than extension, usually follows arthroscopic releases, and is never used in a reactive knee. In cases where an anatomical block to motion is identified (e.g., graft impingement, Cyclops lesion) surgical treatment is advocated. In the early period following ACL reconstruction, loss of extension is due to pathology between the graft and the fat pad, and loss of flexion is usually due to adhesion formation in the suprapatellar pouch and medial and lateral gutters. Arthroscopic débridement of fibrotic nodules in front of the graft, roofplasty, or lysis of adhesions in the suprapatellar pouch and gutters can successfully address postoperative loss of motion.33,49 In more severe cases of global knee arthrofibrosis or advanced stages of infrapatellar contracture syndrome, open débridement is necessary. Delay for several months to allow subsidence of the inflammation of the knee may be necessary. Attempts to mobilize an inflamed knee usually prove unsuccessful, and therefore it is preferable to work on muscle strength through the available ROM while waiting for resolution of the inflammation. A thorough débridement of scar tissue is performed through a lateral and/or limited medial arthrotomy, with special attention paid to the anterior compartment of the knee. A malpositioned, overtensioned, or impinged graft that blocks motion is excised. Protruding hardware is removed or trimmed. In long-standing cases, posterior capsular releases may rarely be required to correct a flexion contracture.

CONCLUSIONS The growing body of knowledge on ACL reconstruction has helped to reduce the incidence of postoperative stiffness. To further minimize this complication, the surgeon should carefully evaluate the connective tissue profile of the patient, delay surgery whenever possible to allow subsidence of the 570

posttraumatic inflammation, and apply meticulous surgical technique especially in issues such as handling of the fat pad, tunnel placement, graft isometry, and tensioning. In the postoperative period, prolonged immobilization should be avoided and the rehabilitation protocol should respect the individual response of the operated knee. Early recognition of failure to gain knee motion is paramount, as appropriate intervention can ameliorate this complication in the majority of cases.

References 1. Aglietti P, Giron F, Buzzi R, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. A prospective, randomized clinical trial. J Bone Joint Surg 2004;86A:2143–2155. 2. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament: a comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 3. Williams RJ, Hyman J, Petrigliano F, et al. Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg 2004;86A:225–232. 4. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83A:348–354. 5. Pinczewski LA, Deehan DJ, Salmon LJ. A five-year comparison of patellar tendon versus four-strand hamstring tendon autograft for arthroscopic reconstruction of anterior cruciate ligament. Am J Sports Med 2002;30:523–536. 6. Shaieb MD, Kan DM, Chang SK, et al. A prospective randomized comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:214–220. 7. Harner CD, Irrgang JJ, Paul J, et al. Loss of motion after anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:499–506. 8. Shelbourne KD, Patel DV, Martini DJ. Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction. Am J Sports Med 1996;24:857–862. 9. Wahl SM. Transforming growth factor beta: the good, the bad, and the ugly. J Exp Med 1994;180:1587–1590. 10. Shah M, Foreman D, Ferguson M. Neutralization of TGF-beta 1 and TGF-beta 2 or exogenous addition of TGF-beta 3 to cutaneous rat wounds reduces scarring. J Cell Sci 1995;108:985–1002. 11. Skutek M, Elsner HA, Slateva K, et al. Screening for arthrofibrosis after anterior cruciate ligament reconstruction: analysis of association with human leukocyte antigen. Arthroscopy 2004;20:469–473. 12. Paulos LE, Rosenberg TD, Drawbert J, et al. Infrapatellar contracture syndrome: an unrecognized cause of knee stiffness with patella entrapment and patella infera. Am J Sports Med 1987;15:331–341. 13. Mohamed-Ali V, Pinkney JH, Coppack SW. Adipose tissue as an endocrine and paracrine organ. Int J Obesity 1998;22:1145–1158. 14. Ushiyama T, Chano T, Inoue K, et al. Cytokine production in the infrapatellar fat pad: another source of cytokines in knee synovial fluids. Ann Rheum Dis 2003;62:108–112. 15. Murakami S, Muneta T, Ezura Y, et al. Quantitative analysis of synovial fibrosis in the infrapatellar fat pad before and after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:29–34. 16. Hunter RE, Mastrangelo J, Freeman JR, et al. The impact of surgical timing on postoperative motion and stability following anterior cruciate ligament reconstruction. Arthroscopy 1996;12:667–674. 17. Majors RA, Woodfin B. Achieving full range of motion after anterior cruciate ligament reconstruction. Am J Sports Med 1996;24:350–355.

Stiffness: Prevention and Treatment 18. Marcacci M, Zaffagnini S, Iacono F, et al. Early versus late reconstruction for anterior cruciate ligament rupture. Results after five years of follow-up. Am J Sports Med 1995;23:690–693. 19. Shelbourne KD, Wilckens JH, Mollabashy A, et al. Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation. Am J Sports Med 1991;19:332–336. 20. Strum GM, Friedman MJ, Fox JM, et al. Acute anterior cruciate ligament reconstruction: analysis of complications. Clin Orthop Relat Res 1990;Apr:184–189. 21. Meighan AA, Keating JF, Will E. Outcome after reconstruction of the anterior cruciate ligament in athletic patients. A comparison of early versus delayed surgery. J Bone Joint Surg 2003;85B:521–524. 22. Shelbourne KD, Foulk DA. Timing of surgery in acute anterior cruciate ligament tears on the return of quadriceps muscle strength after reconstruction using an autogenous patellar tendon graft. Am J Sports Med 1995;23:686–689. 23. Robins AJ, Newman AP, Burks RT. Postoperative return of motion in anterior cruciate ligament and medial collateral ligament injuries. The effect of medial collateral ligament rupture location. Am J Sports Med 1993;21:20–25. 24. Noyes FR, Barber-Westin SD. Revision anterior cruciate ligament reconstruction: report of 11-year experience and results in 114 consecutive patients. Instr Course Lect 2001;50:451–461. 25. Hefzy MS, Grood ES, Noyes FR. Factors affecting the region of most isometric femoral attachments. Part II: the anterior cruciate ligament. Am J Sports Med 1989;17:208–216. 26. Sapega AA, Moyer RA, Scheck C, et al. Testing for isometry during reconstruction of the anterior cruciate ligament. Anatomical and biomechanical considerations. J Bone Joint Surg 1990;72A:259–267. 27. Graf B. Isometric placement of substitutes for the anterior cruciate ligament. In Jackson DW, Drez D (eds). The anterior cruciate deficient knee. St Louis, 1987, Mosby, pp 102–113. 28. Fleming BC, Beynnon BD, Nichols CE, et al. An in vivo comparison between intraoperative isometric measurement and local elongation of the graft after reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1994;76A:511–519. 29. Clancy WG, Ray JM, Zoltan DJ. Acute tears of the anterior cruciate ligament. Surgical versus conservative treatment. J Bone Joint Surg 1988;70A:1483–1488. 30. O’Meara PM, O’Brien WR, Henning CE. Anterior cruciate ligament reconstruction stability with continuous passive motion. The role of isometric graft placement. Clin Orthop Relat Res 1992;Apr:201–209. 31. Howell SM, Taylor MA. Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg 1993;75A:1044–1055. 32. Girgis FG, Marshall JL, Monajem A. The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis. Clin Orthop Relat Res 1975;106:216–231. 33. Jackson DW, Schaefer RK. Cyclops syndrome: loss of extension following intra-articular anterior cruciate ligament reconstruction. Arthroscopy 1990;6:171–178.

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34. Marzo JM, Bowen MK, Warren RF, et al. Intraarticular fibrous nodule as a cause of loss of extension following anterior cruciate ligament reconstruction. Arthroscopy 1992;8:10–18. 35. Romano VM, Graf BK, Keene JS, et al. Anterior cruciate ligament reconstruction. The effect of tibial tunnel placement on range of motion. Am J Sports Med 1993;21:415–418. 36. Muneta T, Yamamoto H, Ishibashi T, et al. The effects of tibial tunnel placement and roofplasty on reconstructed anterior cruciate ligament knees. Arthroscopy 1995;11:57–62. 37. Howell SM, Gittins ME, Gottlieb JE, et al. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. 38. Hutchinson MR, Bae TS. Reproducibility of anatomic tibial landmarks for anterior cruciate ligament reconstructions. Am J Sports Med 2001;29:777–780. 39. Howell SM. Principles for placing the tibial tunnel and avoiding roof impingement during reconstruction of a torn anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 1998;6:S49–S55. 40. Yasuda K, Tsujino J, Tanabe Y, et al. Effects of initial graft tension on clinical outcome after anterior cruciate ligament reconstruction. Autogenous doubled hamstring tendons connected in series with polyester tapes. Am J Sports Med 1997;25:99–106. 41. Hamner DL, Brown CH Jr, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg 1999;81A:549–557. 42. Heis FT, Paulos LE. Tensioning of the anterior cruciate ligament graft. Orthop Clin North Am 2002;33:697–700. 43. Bylski-Austrow DI, Grood ES, Hefzy MS, et al. Anterior cruciate ligament replacements: a mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension. J Orthop Res 1990;8:522–531. 44. Paulos LE, Noyes FR, Grood ES. Knee rehabilitation after anterior ligament reconstruction and repair. Am J Sports Med 1981;9:140–149. 45. Poehling GG, Pollock FE Jr, Koman LA. Reflex sympathetic dystrophy of the knee after sensory nerve injury. Arthroscopy 1988;4:31–35. 46. Misra R, Strover A, El-Shazly M. Intra-articular protrusion of malpositioned Transfix implant following anterior cruciate ligament reconstruction. Arthroscopy 2006;22:226.e1–226.e4. 47. Millett PJ, Wickiewicz TL, Warren, RF. Motion loss after ligament injuries to the knee: part II: prevention and treatment. Am J Sports Med 2001;29:822–828. 48. Howell SM, Berns GS, Farley TE. Unimpinged and impinged anterior cruciate ligament grafts: MR signal intensity measurements. Radiology 1991;179:639–643. 49. Fisher SE, Shelbourne KD. Arthroscopic treatment of symptomatic extension block complicating anterior cruciate ligament reconstruction. Am J Sports Med 1993;21:558–564.

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73 CHAPTER

Lars Ejerhed Jüri Kartus

Osteoporosis After Anterior Cruciate Ligament Reconstruction? ANTERIOR CRUCIATE LIGAMENT INJURIES AND THEIR TREATMENT Anterior cruciate ligament (ACL) injuries are usually sustained by a young and active population, often under heavy pressure to continue heavy labor or sports activities at a competitive or recreational level. The natural history of an ACL injury still remains unclear. Conservative (nonsurgical) treatment has been reported to produce unsatisfactory results, such as chronic instability, muscle weakness, and osteoarthritis (OA), but also to render acceptable function for some patients.1 It is a common algorithm that surgical intervention is recommended if the patient requests a return to high-risk pivoting sports or if symptoms of giving way are persistent after a conservative program. To our knowledge, however, this has not been scientifically proven in randomized controlled studies. ACL surgery and reconstruction with different types of autograft such as patellar or hamstring tendons have been shown to produce good and predictable results. The majority of patients can return to heavy labor and sports activities, but normally on a lower level than before the injury. However, the reconstructions are often associated with donor site problems that are well documented in the literature. These problems involve anterior knee pain, patellofemoral tenderness and the development of OA, patellar tendon shortening, loss of sensitivity in the anterior knee region, discomfort during kneeling and knee-walking, and loss of muscular strength.

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Another less documented but reported side effect after ACL injury and ACL surgery is the risk of localized or systemic bone loss. In some respects, the ACL injured patient is selection biased. The injury usually occurs during sporting activities. The patients are often young, well-trained athletes and have all the requirements to have a good bone mass. We know that athletes have higher bone density than the normal population, a combined effect of training and selection, as it is probably more likely that people with good muscle strength choose to play soccer/football compared with smaller individuals.

PEAK BONE MASS AND NATURAL BONE LOSSES We start adult life with a peak bone mass, 80% of which is determined by genetic factors. This is also the case for fat and muscle tissue, 65% to 80% of which are genetically determined. Men have a higher peak bone mass than women (Fig. 73-1). During childhood and adolescence, it is possible to increase bone mass with sufficient nutrition and physical activity. However, the positive effect of training during childhood and adolescence appears to be lost with the cessation of a sporting career.2 From the peak bone mass at the age of 25 years, there is an annual loss of approximately 0.5% to 1%. The loss for women is accelerated in connection with menopause and, during the

Osteoporosis After Anterior Cruciate Ligament Reconstruction? Bone mass Peak bone mass

Menopause

Age 25 years

45-55 years

FIG. 73-1 Schematic bone mass curves showing the peak bone mass and the subsequent loss with age. (Men are represented by the unbroken line and women by the dotted line.)

subsequent 10 years, the annual loss is as much as 2% to 4% (see Fig. 73-1). The bone metabolism turnover rate is 4 to 10 times higher in trabecular bone compared with cortical bone. The content of trabecular bone in the calcaneus is 95%; in the lumbar vertebrae, 40%; and in the neck of the femur, 40%. In a period of 8 years, the bone tissue is completely replaced. The potential as an adult to compensate for a low peak bone mass or significantly to increase bone mass by strenuous exercise or an excessive intake of calcium/vitamin D appears to be virtually nonexistent. However, the female athlete triad, a disorder in young females characterized by eating disturbances, amenorrhea, and osteoporosis, could be an exception. For these individuals, there is still the potential for “catch-up” in bone mass in the third decade of life if the condition is reversed. The normal physiological bone loss seen during pregnancy and breastfeeding also appears to be reversible.

OSTEOPOROSIS The World Health Organization (WHO) has proposed a definition for osteoporosis based on bone mineral density measured using the dual-energy X-ray absorptiometry (DXA) technique in the hip, vertebra, or distal radius in postmenopausal women. Osteoporosis is defined as bone mineral density more than 2.5 standard deviations below the mean value for young adults in the same population. Osteoporosis and its consequences, with an increasing fracture incidence among the aging population in Western countries, have become a challenge to general public health and the welfare system. There are many known risk factors for osteoporosis and/or fractures. They can be divided into (1) nontreatable risk factors such as older age, previous fracture, female gender, menopausal age, heredity, ethnicity,

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and body height and (2) treatable risk factors such as physical inactivity, low body weight/low body mass index (BMI), cortisone treatment, low bone density, tendency to fall, tobacco smoking, alcohol consumption, low exposure to sunlight, impaired vision, and calcium and vitamin D deficiency.3 Older age and a history of previous fractures are regarded as by far most important risk factors. Osteoporosis is a silent condition with no symptoms, and the clinical manifestation is usually a low-energy fracture in the vertebra, distal radius, proximal humerus, or hip. The Scandinavian countries of Norway, Iceland, Sweden, and Denmark top the global list for the incidence of hip fractures. The incidence of hip fractures will be an increasing problem worldwide due to an aging population.

BONE LOSS AND MUSCULOSKELETAL INJURIES Local and generalized bone loss is reported in the literature to be associated with musculoskeletal injury and physical inactivity. The bone loss caused by inactivity might be prevented at least in the early phase of inactivity through increased weight bearing, exercise, or medication. Fractures in the lower extremities are reported to cause bone loss. Andersson and Nilsson4 reported a loss of 25% in the proximal tibia and fibula 1 year after tibial shaft fractures. The loss was found irrespective of treatment in a below-knee brace with weight bearing or a long leg plaster without weight bearing. Nine years after tibial fractures, Kannus et al reported approximately 10% lower bone mineral density in the spine and in the knee region in the injured leg compared with the noninjured leg.5 Andersson and Nilsson6 also found a loss of bone mineral in the knee region after knee ligament injuries. The average loss after 1 year was 10% in the nonoperated group treated with a knee bandage for a short time and 18% in the operated group treated with a plaster cast for 5 weeks. To summarize, fractures, knee ligament injuries, and meniscal tears cause a loss of bone mineral. This degradation process appears to be rapid, but the bone formation process is slow and it is unclear whether this loss can ever be completely recovered.

ANTERIOR CRUCIATE LIGAMENT SURGERY AND THE EFFECT ON BONE TISSUE Kannus et al reported a 3% to 9% lower bone mineral density in the knee region compared with the noninjured knee 10 to 11 years after ACL injuries treated surgically. The injured knee had a reduction of 6% in the distal femur, 9% in the patella, and 3% in the proximal tibia. However, no differences were found in the calcaneus and femoral 573

Anterior Cruciate Ligament Reconstruction neck. When examining patients with medial collateral ligament injuries, no reduction was found compared with the noninjured side, although the immobilization period was the same (cast for 6–7 weeks). The authors speculated that using rehabilitation braces and early weight bearing instead of immobilization in a plaster cast after ACL reconstruction could prevent osteoporosis.7 In a cross-sectional study, Kartus et al8 reported that male patients with unilateral ACL injury had a significantly lower bone mass in the calcaneus on the injured side compared with the noninjured side before primary reconstruction, 2 years after primary reconstruction, and 2 years after revision surgery. Furthermore, the time period between the injury and the index operation did not correlate with the bone mass. However, a high level of activity correlated with the bone mass on both the injured and the uninjured side 2 years after primary reconstruction. Leppala et al9 found a bone loss of 14% to 21% in the knee region in the affected extremity 1 year after ACL reconstruction. In a conservatively treated group (complete or partial ACL tears), they found a small yet significant bone loss in the patella (3%) and proximal tibia (2%) on the affected side. The “healthy” extremity was not measured, however. Ejerhed et al10 reported a bone loss of approximately 17% in both calcanei 2 years after ACL reconstruction using the arthroscopic technique, bone–patellar tendon–bone (BPTB) grafts, and aggressive rehabilitation. The patients underwent surgery 1 year after ACL injury, and by that time they had a low activity level but still had bone mineral values above those of the normal population. Two years after the reconstruction, the patients had regained most of their desired activity level more than 1 year earlier, but with bone mineral values far below the normal (Fig. 73-2). The previously proposed explanation for excessive bone loss due to inactivity 0.6

BMA (g/cm2)

0.55 0.5

Normal Female Normal Male

0.45 0.4 0.35 0.3 Preop

2 years

FIG. 73-2 A schematic representation of the bone mineral loss found by Ejerhed et al10 in the calcanei from the preoperative assessment and 2 years after anterior cruciate ligament (ACL) reconstruction (dotted lines). The unbroken lines show the expected loss due to aging for males and females, respectively.

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therefore appeared to be of minor importance, at least in that study. It might be that bone mineral decreases in the knee region as a result of the surgical trauma to the knee during reconstruction. The technique used for the reconstruction, BPTB, removes a substantial amount of bone tissue in the knee region (femoral condyle, patella, and tibial condyle). Another proposed explanation for the localized bone loss in the knee region is that harvesting the central third of the patellar tendon causes a weakening in an intact tendon. This leads to reduced forces acting on this region, with a subsequent bone loss in the patella and the proximal tibia.11 It therefore appears to be suboptimal to measure the bone mass in the knee region when the aim is to evaluate the effect of early weight bearing and rehabilitation. Another reason to perform measurements in the calcanei is that this bone consists of about 95% trabecular bone and could therefore be a fast, sensitive indicator of the bone remodeling process.

SURGERY: A RISK FACTOR FOR OSTEOPOROSIS? The reported bone loss of 10% to 20% in young adults after ACL surgery and a suspicion that this is not a reversible process might cause future problems. The question is whether the surgical trauma itself could be a risk factor for osteoporosis later in life. Can surgery initiate increased and accelerated bone resorption and a negative bone balance metabolism? Is there any support for this speculation in the literature? It is worth noting that no study focusing on surgery and bone mineral loss has actually been found in the literature. Alfredson et al reported that a group of patients selected for operative treatment of chronic Achilles tendinosis had a bone loss of 16.4% on the injured side compared with the noninjured side, 12 months postoperatively. In a group of patients selected for heavy-loaded eccentric calf-muscle training, there was no side-to-side difference in bone mass in the calcanei 9 months after the start of the training program. Both groups had good clinical results with recovery in muscle strength on both the injured and noninjured sides.12 The study by Leppala et al9 is the only study found in the literature relating to bone loss after ACL injuries treated either surgically or conservatively. The authors found bone loss in the patella of 17% versus 2% and in the proximal tibia of 17% versus 3% in the surgically and nonsurgically treated groups, respectively. This represents a fivefold to eightfold difference in the loss of bone between the study groups. The explanations proposed by the authors were the different treatments (either surgical or conservative). The patients had different types of injury and rehabilitation; in the

Osteoporosis After Anterior Cruciate Ligament Reconstruction? conservatively treated group there were also some partial tears, and in the surgically treated group, a longer non– weight-bearing period. The finding in the study by Ejerhed et al that the bone loss was 16% and 17% in both calcanei 2 years after ACL reconstruction is unexpected.10 In spite of the relatively long period of reduced activity level before reconstruction, the aggressive rehabilitation program, and significantly higher activity level postoperatively, the authors were not able to find any restoration of bone mass during the follow-up period of 2 years. The strength of this study was that the bone mass was measured in a prospective manner on both the injured and noninjured sides. Frequently in previous studies, a comparison has been made between the injured side and the “healthy” contralateral side. By doing so, there is an obvious risk of drawing the wrong conclusion if small or no differences are found. It is easy to miss a progressive process. For instance, if the 2-year assessment had just been made in this study, a difference of only 2.5% would have been found between the injured and noninjured sides. The excessive reduction in bone mass in both calcanei in this study, together with the results of other studies, indicates that the described bone loss can be an effect of the surgical intervention. Furthermore, it appears that the positive effect of increased activity level is of minor importance. Could ACL injury followed by reconstructive surgery be a risk factor for osteoporosis later in life? It is hoped that forthcoming studies will examine the impact of surgery on bone loss and the subsequent development of osteoporosis. Another question for the future, which is not discussed in this chapter, is the alteration in subchondral bone mass and its connection with the development of OA. In the case of ACL injury, every patient should have an individual treatment plan based on the symptoms and the need to continue with heavy labor or the desire to

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participate in competitive/recreational sports. The patient should be informed of the realistic expectations of reconstructive surgery and its known limitations and complications.

References 1. Casteleyn PP, Handelberg F. Non-operative management of anterior cruciate ligament injuries in the general population. J Bone Joint Surg 1996;78B:446–451. 2. Karlsson MK, Linden C, Karlsson C, et al. Exercise during growth and bone mineral density and fractures in old age. Lancet 2000;355:469–470. 3. SBU, Bone density measurement—a systematic review. A report from SBU, the Swedish Council on Technology Assessment in Health Care. J Intern Med Suppl 1997;739:1–60. 4. Andersson SM, Nilsson BE. Post-traumatic bone mineral loss in tibial shaft fractures treated with a weight-bearing brace. Acta Orthop Scand 1979;50:689–691. 5. Kannus P, Järvinen M, Sievanen H, et al. Osteoporosis in men with a history of tibial fracture. J Bone Miner Res 1994;9:423–429. 6. Andersson SM, Nilsson BE. Changes in bone mineral content following ligamentous knee injuries. Med Sci Sports 1979;11:351–353. 7. Kannus P, Sievanen H, Järvinen M, et al. A cruciate ligament injury produces considerable, permanent osteoporosis in the affected knee. J Bone Miner Res 1992;7:1429–1434. 8. Kartus J, Stener S, Nilsen R, et al. Bone mineral assessments in the calcaneus after anterior cruciate ligament injury. An investigation of 92 male patients before and two years after reconstruction or revision surgery. Scand J Med Sci Sports 1998;8:449–455. 9. Leppala J, Kannus P, Natri A, et al. Effect of anterior cruciate ligament injury of the knee on bone mineral density of the spine and affected lower extremity: a prospective one-year follow-up study. Calcif Tissue Int 1999;64:357–363. 10. Ejerhed L, Kartus J, Nilsen R, et al. The effect of anterior cruciate ligament surgery on bone mineral in the calcaneus: a prospective study with a 2-year follow-up evaluation. Arthroscopy 2004;20:352–359. 11. Rittweger J, Maffulli N, Maganaris CN, et al. Reconstruction of the anterior cruciate ligament with a patella-tendon-bone graft may lead to a permanent loss of bone mineral content due to decreased patellar tendon stiffness. Med Hypotheses 2005;64:1166–1169. 12. Alfredson H, Nordström P, Pietila T, et al. Bone mass in the calcaneus after heavy loaded eccentric calf-muscle training in recreational athletes with chronic achilles tendinosis. Calcif Tissue Int 1999;64:450–455.

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74 CHAPTER

Chadwick C. Prodromos Brian T. Joyce

Tunnel Widening After Anterior Cruciate Ligament Reconstruction INTRODUCTION Tunnel widening after anterior cruciate ligament reconstruction (ACLR) has been noted for many years. Initially there were concerns that this widening would be progressive. However, it is now clear that tunnel widening only occurs in the first postoperative year1,2 and is not progressive after that period. A number of variables have been hypothesized to cause or contribute to tunnel widening. These include the following: 1 Hamstring (HS) versus bone–patellar tendon–bone (BPTB) graft 2 Allograft versus autograft 3 Fixation location: cortical versus apertural 4 Rehabilitation: the aggressiveness of the postoperative rehabilitation protocol 5 Synovial fluid: the degree to which synovial fluid penetrates into the tunnel These potential etiologies and the significance of tunnel widening will be discussed in this chapter.

METHODS OF ANALYZING TUNNEL WIDENING Quantifying Tunnel Widening There is no established standard method for quantifying tunnel widening. Most authors have compared tunnel widths at a specified point(s) within the tibial and/or femoral tunnels and 576

calculated the increase in tunnel size relative to the original tunnel size. The elapsed interval of time after the surgery is also specified. Plain radiographs are usually measured, but computed tomography (CT) or magnetic resonance imaging (MRI) may also be used.

Literature Analysis The literature with regard to tunnel widening can be evaluated in two ways. The first is to aggregate and analyze the amount of tunnel widening reported in all series that use one surgical technique and contrast it to that found in all series using a contrasting surgical technique (i.e., interseries analysis). This can be used to compare, for example, mean tunnel widening in HS series versus BPTB series. The second method is to look at those series that use both techniques within a given series (i.e., intra-series analysis). Both methods were used in this analysis so that the entirety of the tunnel widening literature could be analyzed. Both methods contributed useful information. In general, good agreement was also found between each method for a given parameter.

SPECIFIC FACTORS ASSOCIATED WITH INCREASED TUNNEL WIDENING Hamstring Versus Bone–Patellar Tendon–Bone Graft It has been hypothesized that HS grafts are associated with more tunnel widening than

Tunnel Widening After Anterior Cruciate Ligament Reconstruction BPTB grafts. Tunnel widening has been found with the use of both grafts. Seven series specifically compared HS with BPTB. However, because fixation is different for the HS and BPTB grafts in all these series and because fixation type is one of the leading hypothetical causes of tunnel widening, the isolated effect of graft type is difficult to discern. Of these seven series,2–8 two report tunnel widening that is roughly equal for HS and BPTB and five report more tunnel widening with HS. These seven series are presented in bar graph form in Fig. 74-1.

Allograft Versus Autograft Two clinical series9,10 have shown increased tunnel widening in allografts versus autografts. In addition, a recent sheep study by Weiler showed increased tunnel widening in allografts at all time periods measured, beginning at 6 weeks and ending at 1 year.11 Possible causes include an increased immunologic response to the graft or the presence of chemical residua in the grafts from processing, cleansing, cryoprotectant, radioprotectant, or the like.

Effects of Fixation Location It has been suggested that the increased incidence of tunnel widening in HS ACLR may be due to fixation. Specifically, a “windshield wiper” effect resulting in greater tunnel widening when the fixation is further from the joint, as is more often

Aglietti

Clatworthy

Hersekli

4HS (Tibial) BPTB (Tibial)

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the case with HS than BPTB graft fixation techniques, has been hypothesized. It is theorized that with knee motion, the pressure of the graft on the tunnel wall will vary more with cortical or mid-tunnel (cross-pin) than aperture fixation, producing attrition of the tunnel wall. A review of the literature in this regard does not show a consistent effect of the location of the fixation.12–17 The four studies comparing aperture to cortical or cross-pin fixation are presented in Fig. 74-2.

Aggressive Versus Conservative Rehabilitation The effect of motion and rehabilitation has been addressed in three studies in which different postoperative protocols were used by the same surgeon after ACLR.18–20 The study by Hantes et al18 showed significantly decreased tunnel widening when motion was restricted after ACLR. The study by Yu and Paessler20 also showed significantly decreased tunnel widening when motion, weight-bearing, and strengthening activities were all restricted. The study by Murty et al19 showed the opposite: significantly increased tunnel widening when motion was restricted after ACLR.

Synovial Fluid Infiltration Synovial fluid in the bone tunnels has been hypothesized as a possible cause of tunnel widening without a specific mechanism; it has been suggested that “enzymes” in synovial fluid

Harilainen L’Insalata

Webster

Zysk

4HS (Femoral) BPTB (Femoral)

FIG. 74-1 Tunnel widening by graft and fixation type. BPTB, Bone–patellar tendon–bone; HS, hamstring.

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Anterior Cruciate Ligament Reconstruction

Interference Screw Fixation For those surgeons who use interference screws, a widened tunnel will generally make interference screw usage impossible with the original tunnel if the original tunnel was reasonably well placed. However, if the widened tunnel was severely misplaced far from its proper location, the surgeon may be able to make an entirely new tunnel that does not overlap the widened tunnel and use an interference screw in the new tunnel.

Noninterference Screw Fixation For those using cortical or mid-tunnel cross-pin fixation, a reasonably well-placed original tunnel may still be able to be used in a one-stage revision. The surgeon will have a looser fit but may wish to accept this and allow greater time for tunnel healing to avoid the morbidity and second-stage requirement of bone grafting, depending on the amount of tunnel enlargement.

Strategies to Decrease Tunnel Widening

Aperture (Tibial) Cortical (Tibial)

Aperture (Femoral) Mid-tunnel (Femoral)

FIG. 74-2 Tunnel enlargement by fixation type.

may in some fashion break down bone. It has been hypothesized that applying an apertural seal may prevent this breakdown. In one of the only studies to look at this issue,21 no tunnel widening was found with HS grafts despite the presence of synovial fluid in bone tunnels.

ADVERSE EFFECTS

CONCLUSIONS 1 No standardized method exists for reporting tunnel widening.

Direct Adverse Effects

2 Tunnel widening occurs only in the first postoperative year.

No direct adverse event such as fracture or graft failure has yet been reported as a result of tunnel widening. The realization that the phenomenon is not progressive over time has assuaged early fears that progressive widening might result in significant weakening of the bony elements.

3 Allografts appear to cause more tunnel widening than autografts.

Effects on Revision Surgery The only indirect adverse consequence of tunnel widening is its potential effect on revision of failed ACLRs. Tunnel widening adversely affects revision surgery, depending partially on the revision technique used. A detailed description is presented in Chapter 57.

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Until the causes of tunnel widening are better understood, strategies to diminish it will be speculative. Many believe that the use of either bone graft22 or osteoconductive interference screws such as the Milagro (Mitek, Raynham, MA) or Collaxo (Smith & Nephew, Andover, MA) will be likely to decrease tunnel widening. However, although anecdotal corroborative evidence exists, we are not aware of any published report that validates this hypothesis.

4 HS grafts appear to be associated with greater tunnel widening than BPTB grafts. 5 Fixation location, fixation type, and synovial fluid appear to have no effect on tunnel widening. 6 Postoperative motion and activity have been to shown to both decrease and increase tunnel widening, with more evidence showing restricted activity to diminish tunnel widening. 7 No direct adverse consequence of tunnel widening has yet been reported.

Tunnel Widening After Anterior Cruciate Ligament Reconstruction 8 Revision surgery, especially with interference screws, is often made more difficult by tunnel widening. 9 No strategy has thus far been shown to decrease tunnel widening, although some surgeons believe tunnel bone grafting may prove effective.

References 1. Lajtai G, Noszian I, Humer K, et al. Serial magnetic resonance imaging evaluation of operative site after fixation of patellar tendon graft with bioabsorbable interference screws in anterior cruciate ligament reconstruction. Arthroscopy 1999;15:709–718. 2. Clatworthy MG, Annear P, Buelow J-U, et al. Tunnel widening in anterior cruciate ligament reconstruction: a prospective evaluation of hamstring and patella tendon grafts. Knee Surg Sports Traumatol Arthrosc 1999;7:138–145. 3. Aglietti P, Giron F, Buzzi F, et al. Anterior cruciate ligament reconstruction: bone-patellar tendon-bone compared with double semitendinosus and gracilis tendon grafts. J Bone Joint Surg 2004;86A:2143–2155. 4. Hersekli MA, Akpinar S, Ozalay M, et al. Tunnel enlargement after arthroscopic anterior cruciate ligament reconstruction: comparison of bone-patellar tendon-bone and hamstring autografts. Adv Ther 2004;21:123–131. 5. L’Insalata JC, Klatt B, Fu FH, et al. Tunnel expansion following anterior cruciate ligament reconstruction: a comparison of hamstring and patellar tendon autografts. Knee Surg Sports Traumatol Arthrosc 1997;5:234–238. 6. Webster KE, Feller JA, Hameister KA. Bone tunnel enlargement following anterior cruciate ligament reconstruction: a randomized comparison of hamstring and patellar tendon grafts with 2-year followup. Knee Surg Sports Traumatol Arthrosc 2001;9:86–91. 7. Zysk SP, Fraunberger P, Veihelmann A, et al. Tunnel enlargement and changes in synovial fluid cytokine profile following anterior cruciate ligament reconstruction with patellar tendon and hamstring tendon autografts. Knee Surg Sports Traumatol Arthrosc 2004;12:98–103. 8. Harilainen A, Linko E, Sandelin J. Randomized prospective study of ACL reconstruction with interference screw fixation in patellar tendon autografts versus femoral metal plate suspension and tibial post fixation in hamstring tendon autografts: 5-year clinical and radiological follow-up results. Knee Surg Sports Traumatol Arthrosc 2006;14:517. 9. Fahey M, Indelicato PA. Bone tunnel enlargement after anterior cruciate ligament replacement. Am J Sports Med 1994;22:410–414.

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10. Zijl JAC, Kleipool AEB, Willems WJ. Comparison of tibial tunnel enlargement after anterior cruciate ligament reconstruction using patellar tendon autograft or allograft. Am J Sports Med 2000;28:547–551. 11. Scheffler S, Unterhauser F, Keil J, et al. In Comparison of tendon-tobone healing after soft-tissue autograft and allograft ACL reconstruction in a sheep model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Austria, May, 2006. 12. Buelow J-U, Siebold R, Ellermann A. A prospective evaluation of tunnel enlargement in anterior cruciate ligament reconstruction with hamstrings: extracortical versus anatomical fixation. Knee Surg Sports Traumatol Arthrosc 2002;10:80–85. 13. Harilainen A, Sandelin J, Jansson KA. Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33. 14. Ma CB, Francis K, Towers J, et al. Hamstring anterior cruciate ligament reconstruction: a comparison of bioabsorbable interference screw and endobutton-post fixation. Arthroscopy 2004;20:122–128. 15. Sakai H, Yajima H, Hiraoka H, et al. The influence of tibial fixation on tunnel enlargement after hamstring anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:364–370. 16. Simonian PT, Erickson MS, Larson RV, et al. Tunnel expansion after hamstring anterior cruciate ligament reconstruction with 1-incision Endobutton femoral fixation. Arthroscopy 2000;16:707–714. 17. Simonian PT, Monson JT, Larson RV. Biodegradable interference screw augmentation reduces tunnel expansion after ACL reconstruction. Am J Knee Surg 2001;14:104–108. 18. Hantes ME, Mastrokalos DS, Yu J, et al. The effect of early motion on tibial tunnel widening after anterior cruciate ligament replacement using hamstring tendon grafts. Arthroscopy 2004;20:572–580. 19. Murty AH, Zebdeh MY, Ireland J. Tibial tunnel enlargement following anterior cruciate reconstruction: does post-operative immobilization make a difference? Knee 2001;8:39–43. 20. Yu JK, Paessler HH. Relationship between tunnel widening and different rehabilitation procedures after anterior cruciate ligament reconstruction with quadrupled hamstring tendons. Chin Med J 2005;118:320–326. 21. Sanders TG, Tall MA, Mulloy JP, Lesis HT. Fluid collections in the osseous tunnel during the first year after anterior cruciate ligament repair using an autologous hamstring graft: Natural history and clinical correlation. J Comput Assist Tomogr 2002;426:617–621. 22. Howell SM, Roos P, Hull ML. Compaction of a bone dowel in the tibial tunnel improves the fixation stiffness of a soft tissue anterior cruciate ligament graft: an in vitro study in a calf tibia. Am J Sports Med 2005;33:719–725.

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Numbness/Saphenous Nerve

CHAPTER

Tomoyuki Mochizuki Keiichi Akita Takeshi Muneta

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INTRODUCTION Leg numbness due to nerve damage is one of the considerable complications after anterior cruciate ligament (ACL) reconstruction using both bone–patellar tendon–bone (BPTB) and medial hamstring tendons. Such patients especially complain of uncomfortable feelings when falling on their knees. Harvesting a BPTB graft includes risks of damaging nerves and causes sensory disturbance.1,2 Pagnani et al3 pointed out the risk of saphenous nerve damage by harvesting medial hamstring tendons in the region of the pes anserinus. Many authors have reported the nerve distribution patterns of the infrapatellar regions.2,4–12 It is well known that both the medial cutaneous nerve of the femoral nerve and the infrapatellar branch of the saphenous nerve are distributed throughout the infrapatellar region and the anterior lower leg region.9,10,12 The saphenous nerve descends laterally along the femoral artery and enters the adductor canal. It then leaves the artery at the distal end of the canal to proceed vertically along the medial side of the knee and runs between the sartorius and gracilis tendons. In contrast, the medial femoral cutaneous nerve originates from the anterior cutaneous branches of the femoral nerve. The medial femoral cutaneous nerve runs laterally to the femoral artery, and then it crosses anteriorly to the artery at the apex of the femoral triangle to be distributed to the anteromedial thigh and the infrapatellar region. Branches of the medial femoral cutaneous nerve and the infrapatellar

branch of the saphenous nerve connect to each other9,10,12 and form the subsartorial plexus in the infrapatellar region.13

BONE–TENDON–BONE AUTOGRAFT Anterior knee pain including leg numbness has been reported as a main complication of ACL reconstruction using BPTB grafts. In previous reports, the rate of postoperative anterior knee pain ranged from 4% to more than 40%.8,14,15 Mishra et al at first described a technique using two horizontal incisions for patellar tendon harvest for the purpose of more cosmetic scarring and reducing pain and flexion limitation.16 Kartus et al17 changed to two vertical incisions and reported of an insensitive area compared with the insensitive area that resulted from a traditional vertical incision, which averaged 24 cm. Tsuda et al18 changed the method of approaching the retinaculum layer, opening it horizontally rather than splitting it to protect nerves using two horizontal incisions, and they reported a 17% rate of postoperative leg numbness. Portland et al19 compared a horizontal incision and a vertical incision and reported a infrapatellar numbness of 43% resulting from a horizontal incision and 59% resulting from a horizontal incision.

HAMSTRING AUTOGRAFT The donor site morbidity associated with harvesting a hamstring tendon graft is well recognized

Numbness/Saphenous Nerve to be less common than that associated with harvesting a BPTB autograft.20 However, sensory disturbance is frequently observed in regions on the anterior lower leg after ACL reconstruction using medial hamstring tendons.21,22

CLINICAL EXAMINATION

incisions (see Fig. 75-1, C). The region was located in the upper half of the lower leg in 10 legs (77%); however, in three legs (23%), the region was wider than others (see Fig. 75-1, B).

ANATOMICAL INVESTIGATIONS

We clinically examined 103 patients who had arthroscopically assisted ACL reconstructions using medial hamstring tendons to investigate the frequencies and areas of sensory disturbance.23 As an operative procedure, we made two horizontal incisions for the arthroscopy portal and one longitudinal incision (2.5–3 cm) at the pes anserinus for the tendon harvest and the tibial drill holes. We performed an insideout technique and used Endobutton (Smith & Nephew Endoscopy, Andover, MA) for femoral fixation. The clinical examination was performed for an average of 13 months (range 6–18 months) after the operation. We detected sensory disturbance on the anterior surface of the lower leg in 60 of 103 (58%) patients. We randomly selected 13 patients with sensory disturbance and neurologically examined in detail the regions of sensory disturbance. The regions of sensory disturbance were of various sizes and shapes (Fig. 75-1). These regions were generally quadrilateral and located lateral to the longitudinal incision for tendon harvest and distal to the horizontal incisions for the arthroscopy portal. In the detailed neurological examination, in 8 of 13 legs (62%) the region was very close to the longitudinal incision (see Fig. 75-1, A to C), and in the other 5 legs (38%) it was relatively far away from the longitudinal incision (see Fig. 75-1, D). The region was lower than the superior end of the longitudinal incisions in 12 of 13 legs (92%); however, in one leg (8%), the region was close to the horizontal

P

75

In our anatomical study, 51 lower limbs of 26 adult cadavers were used.24 In the mediodistal region of the patella, the nerve branches pierced the fascia cruris in various patterns and ran on the outer surface of the fascia to supply the skin (Fig. 75-2). On the outer surface of the fascia, the nerve branches often were connected to each other. In the regions near the horizontal and longitudinal skin incision lines, the nerve branches ran on the outer surface of the fascia cruris in all legs. After complete removal of the fasciae lata and cruris, the origin of the nerve branches was examined. The anterior surface of the lower leg was innervated by branches of the medial femoral cutaneous nerve proximally and by branches of the saphenous nerve distally. In addition, the patellar region was innervated by branches of the intermediate femoral cutaneous nerve superiorly and by branches of the medial femoral cutaneous nerve medially and inferiorly. Compared with our clinical examinations, the sensory disturbance regions were considered to correspond with the regions supplied by the branches of the medial femoral cutaneous and saphenous nerves. In 33 of 51 legs (65%; Fig. 75-3, A, B), the infrapatellar branch of the saphenous nerve ran along the inferoposterior border of the sartorius muscle. The infrapatellar branch of the saphenous nerve pierced the distal part of the sartorius muscle in 16 of 51 legs (31%; see Fig. 75-3, C). In two legs

P

H

4 (31%)

A

3 (23%)

B

1 (8%)

C

5 (38%)

D

FIG. 75-1 Examples of cases of sensory disturbance in 13 legs. A, 4 legs (31%); B, 3 legs (23 %); C, 1 leg (8%); D, 5 legs (38%). P, Skin incision for arthroscopy portal; H, skin incision for tendon harvest.

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Anterior Cruciate Ligament Reconstruction (4%; see Fig. 75-3, D), the branch of the saphenous nerve emerged from the anterosuperior border of the sartorius muscle and ran lateralward horizontally. The infrapatellar region and the anterior region of the lower leg were generally supplied by branches of both the medial femoral cutaneous nerve and the saphenous nerve in various patterns. Branches of the medial femoral cutaneous nerve were also distributed to the anterior surface of the leg in eight legs (16%; see Fig. 75-3, A), and branches of the saphenous nerve were also observed to supply the infrapatellar region in two legs (4%; see Fig. 75-3, D). Branches of these nerves and their connections were distributed to the region around the insertion of the sartorius muscle. At least, therefore, the branches of these two nerves showed a complementary distribution and a broad transitional zone. One or more branches of the nerve ran across the line of the longitudinal incision in 88% of the cases.

P

P

Sa

Sv

DISCUSSION

H

FIG. 75-2 Examples of the distribution of the nerve branches on the fasciae lata and cruris. The nerve branches connect in various manners in the medial infrapatellar region. Some nerve branches pass through the longitudinal skin incision line. H, Skin incision for harvest; P, horizontal skin incision for portal for arthroscopy; Sa, sartorius muscle; Sv, saphenous vein.

In

Mn

In

8 (16%)

Mn

In

B

25 (49%)

Mn

In

C

16 (31%)

D

2 (4%)

FIG. 75-3 Four patterns of the distribution of the nerve branches based on findings of 51 legs. A, Branches of the medial femoral cutaneous nerve are distributed to the anterior leg region (8 legs; 16%). B, Branches of the medial femoral cutaneous nerve are distributed to the infrapatellar region, and branches of the saphenous nerve are distributed to the anterior leg region (25 legs; 49%). C, The infrapatellar branch of the saphenous nerve pierces the sartorius muscle and is distributed to the infrapatellar region (16 legs; 31%). D, The infrapatellar branch of the saphenous nerve emerges from the anterior border of the sartorius muscle and is distributed to the infrapatellar region (2 legs; 4%). In, Intermediate femoral cutaneous nerve; Mn, medial femoral cutaneous nerve; Sn, saphenous nerve.

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Mn

Sn

Sn

Sn

Sn

A

In numerous clinical anatomical studies, nerve distribution patterns of the infrapatellar region have been discussed.2,4–8,10,25 The nerve branches supplying the skin of the medioinferior region of the patella are recognized as the infrapatellar branch of the saphenous nerve in most studies. However, according to our study and standard anatomy textbooks,13,16 branches of the saphenous nerve and the medial femoral cutaneous nerve, which originate from the anterior cutaneous branches of the femoral nerve, are distributed to this region. In addition, the branches of the medial femoral cutaneous nerve sometimes extend to the anterior lower leg region. Interestingly,

Numbness/Saphenous Nerve although both nerves are clearly distinguishable in origin, it is very difficult to identify the border between their distribution territories due to their numerous connections because of their complementary distribution. On the basis of the detailed clinical and anatomical investigations, the sensory disturbance is considered to be closely related to the skin incisions. Nerve injury due to the incisions used for the arthroscopy portal as well as the related anatomical findings have been reported.2,11 In the present clinical findings, the sensory disturbance region was located in close proximity to the arthroscopy portals in only one case (see Fig. 75-1, C). The branch of the medial femoral cutaneous nerve might have been injured by the incisions for the arthroscopy portal. There have been few reports on nerve injuries related to the skin incision for tendon harvest.13 The line of skin incision for tendon harvest at the pes anserinus runs across the nerve branches originating from the medial femoral cutaneous nerve and the saphenous nerve. In some patients, the region of the sensory disturbance is not adjacent to the longitudinal skin incision (see Fig. 75-1, D). These cases might be explained by the various patterns of the connections and the overlapping distribution territories of the saphenous nerve and the medial femoral cutaneous nerve. The possibility of nerve injury during harvesting of the semitendinosus tendon with a tendon stripper cannot be overlooked. The main trunk of the saphenous nerve runs distally on the medial (outer) surfaces of the tendons of the gracilis and semitendinosus muscles along the medial collateral ligament. Because the sensory disturbance region was located lateral to the longitudinal incision line in all patients, the tendon harvest using a tendon stripper cannot be the main reason for the sensory disturbance. Injury or entrapment of the main trunk of the saphenous nerve has been reported,26,27 but the sensory disturbance region due to such injury is much wider than that found in our study. If the tendon stripper caused the nerve injury, the main trunk of the saphenous nerve could be damaged as well as the branches of the nerve, as previously pointed out by Pagnani.3 Therefore it is very important to be careful of the main trunk of the saphenous nerve due to its close positional relationship to the tendons to avoid sensory disturbance after ACL reconstruction. The complicated anatomical variations of the nerve branches in the infrapatellar region and the anterior lower leg region preclude absolute avoidance in any surgical knee incision (Fig. 75-4). Ebrahein and Mekhail6 described a safety zone to avoid injury of the infrapatellar branch of the saphenous nerve. However, their zone must be supplied by the branches of the medial femoral cutaneous nerve. Therefore it might be very difficult to find a completely safe zone based on the findings of the present anatomical study.24 Nevertheless, an oblique incision for the tendon harvest would be a good candidate to minimize the area of

P

75

P

X Sa

H

Y

Z

FIG. 75-4 Schematic drawings of the nervous distribution zone in the infrapatellar region and the anterior leg region. The infrapatellar region and the anterior lower leg region are divided into three areas based on the distribution of the nervous branches: X, the region distributed by the medial femoral cutaneous nerve; Y, the transitional zone between the regions X and Z; Z, the region distributed by the saphenous nerve. H, Skin incision for tendon harvest; Mn, branches of the medial femoral cutaneous nerve; P, horizontal skin incision for portal for arthroscopy; Sa, sartorius muscle; Sn, branches of the saphenous nerve.

the sensory disturbance to avoid cutting the courses of the various branches of the nerves, based on our findings of the nerve courses and distribution.

References 1. Graf B, Uhr F. Complications of intra-articular anterior cruciate reconstruction. Clin Sports Med 1988;7:835–848. 2. Mochida H, Kikuchi S. Injury to infrapatellar branch of saphenous nerve in arthroscopic knee surgery. Clin Orthop Relat Res 1995;320:88–94. 3. Pagnani MJ, Warner JJP, O’Brien SJ, et al. Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565–571. 4. Arthornthurasook A, Gaew-Im K. Study of the infrapatellar nerve. Am J Sports Med 1988;16:57–59. 5. Arthornthurasook A, Gaew-Im K. The sartorial nerve: its relationship to the medial aspect of the knee. Am J Sports Med 1990;18:41–42. 6. Ebrahein NA, Mekhail AO. The infrapatellar branch of the saphenous nerve: an anatomic study. J Orthop Trauma 1997;11:195–199.

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Anterior Cruciate Ligament Reconstruction 7. Ganzoni N, Wieland K. The ramus infrapatellaris of the saphenous nerve and its importance for medial parapatellar arthrotomies of the knee. Reconstr Surg Traumat 1978;16:95–100. 8. Kartus J, Ejerhed L, Eriksson BI, et al. The localization of the infrapatellar nerves in the anterior knee region with special emphasis on central third patellar tendon harvest: a dissection study on cadaver and amputated specimens. Arthroscopy 1999;15:577–586. 9. Pürner J. [Peripheral course of saphenous nerve.] Anat Anz 1971;129:114–132. 10. Sirang H. [Saphenous nerve: origin, course, and branches.] Anat Anz 1972;130:158–169. 11. Tifford CD, Spero L, Luke T, et al. The relationship of the infrapatellar branches of the saphenous nerve to arthroscopy portals and incisions for ACL surgery: an anatomic study. Am J Sports Med 2000;28:562–567. 12. Von Lanz T, Wachsmuth W. Praktische Anatomie. Band I, Teil 4. Bein und Statik, Berlin, 1972, Springer-Verlag, pp 73–89, 292–300. 13. Berry MM, Starding SM, Bannister LH. Nervous system. In Williams PL, Bannister LH, Berry MM, et al (eds). Gray’s anatomy. The anatomical basis of medicine and surgery, ed 38 (Brit). New York, 1995, Churchill Livingstone, pp 1280–1282. 14. Bach BR Jr, Jones GT, Sweet FA, et al. Arthroscopy-assisted anterior cruciate ligament reconstruction using patellar tendon substitution: two to four-year follow-up results. Am J Sports Med 1994;22:758–767. 15. Shelboune KD, Trumper RV. Preventing anterior knee pain after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:41–47. 16. Mishra AK, Fanton GS, Dillingham MF, et al. Patellar tendon graft harvesting using horizontal incisions for anterior cruciate ligament reconstruction. Arthroscopy 1995;11:749–752. 17. Kartus J, Ejerhed L, Sernert N, et al. Comparison of traditional and subcutaneous patellar tendon harvest: a prospective study of donor site-related problems after ACL reconstruction using different graft harvesting techniques. Am J Sports Med 2000;28:328–335.

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18. Tsuda E, Okamura Y, Ishibashi Y, et al. Techniques for reducing anterior knee symptoms after ACL reconstruction using a bonepatellar tendon-bone autograft. Am J Sports Med 2001;29:450–456. 19. Portland GH, Martin D, Keene G, et al. Injury to the infrapatellar branch of the saphenous nerve in anterior cruciate ligament reconstruction: comparison of horizontal versus vertical harvest site incisions. Arthroscopy 2005;3:281–285. 20. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament: a comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 21. Bertnam C, Porsche M, Hackenbroch MH, et al. Saphenous neuralgia after arthroscopically assisted ACL reconstruction with a semitendinosus and gracilis tendon graft. Arthroscopy 2000;16:763–766. 22. Mochizuki T, Muneta T, Yagishita K, et al. Skin sensory change after arthroscopically-assisted anterior cruciate ligament reconstruction using medial hamstring tendons with a vertical incision. Knee Surg Sports Traumatol Arthrosc 2004;12:198–202. 23. Mochizuki T, Akita K, Muneta T, et al. Anatomical bases for minimizing sensory disturbance after arthroscopically-assisted anterior cruciate ligament reconstruction using medial hamstring tendons. Surg Radiol Anat 2003;25:192–199. 24. Clemente CD (ed). Anatomy of the human body, ed 30 (Am). Philadelphia, 1985, Lea & Febiger, pp 1231–1234. 25. Leonhardt H, Tillmann B. Untere Extremität. In Leonhardt H, Tillmann B, Töndury G, et al (eds). Anatomie des Menschen. Band IV. Topographie der Organsysteme, Systematik der peripheren Leitungsbahnen. Stuttgart, 1988, Georg Thieme Verlag, pp 448–449. 26. Abram LJ, Froimson AI. Saphenous nerve injury. An unusual arthroscopic complication. Am J Sports Med 1991;19:668–669. 27. Kopell HP, Thompson WAL. Knee pain due to saphenous-nerve entrapment. N Engl J Med 1960;263:351–353.

Hardware Complications After Anterior Cruciate Ligament Reconstruction INTRODUCTION A variety of autograft and allograft tissues can be used for reconstruction of the anterior cruciate ligament (ACL), and a number of different tools and techniques can be used to achieve graft fixation, whether bone to bone or tendon to bone. Commonly used fixation devices include interference screws (metallic and bioabsorbable), the Endobutton (Acufex Microsurgical, Mansfield, MA), and cross-pins. Complications related to graft fixation are often specific to the type of fixation used, although a number of recurring themes occur. We will review each type of fixation and the related intraoperative and postoperative complications, as well as methods for managing both types of complication. Obviously, the ideal management is avoidance of the complication in the first place. Skeletally immature patients are susceptible to a unique set of complications regardless of the method of fixation, and we will review this complication separately.

INTERFERENCE SCREWS Interference screws are a widely used method of fixation during ACL reconstruction, both for bone–bone fixation and tendon–bone fixation. A number of complications related to interference screws may be encountered, and these can occur intraoperatively or postoperatively. Intraoperative complications include intraarticular placement of the hardware, which ideally will be recognized during the procedure

and adjusted accordingly (Fig. 76-1). During insertion of the screw, possible complications include laceration of the graft-passing suture,1 advancement of the graft within the bone tunnel,1 graft laceration1 and even rupture,2 fracture of the graft bone plug,3 and screw breakage.4–6 To minimize the risk of lacerating the passing suture, at least one suture can be passed through the tendon at the base of the bone plug.1 To minimize the risk of graft rupture, methylene blue can be used to mark the bone–tendon junction of the graft, the anterior portion of the bone tunnel can be notched to ease the initial engagement of the screw, the cancellous edge of the bone plug can be placed facing anterior flush with the intraarticular edge of the femoral tunnel, and a protective sheath or cannula can be used to protect the graft during screw placement.2 Another helpful technique to protect the graft is to insert the femoral screw over a guidewire drilled through a cannulated screwdriver. If the graft ruptures during screw placement, a number of salvage options may be used. If a patellar tendon graft is cut at the bone– tendon junction, the graft can be reversed, placing the intact bone plug in the femoral tunnel and fixing the tendinous portion of the graft through the tibial tunnel with a post or button.2,7 If the remaining graft length is insufficient, an alternative autograft or allograft should be used. To minimize the chance of graft advancement, it is important to maintain constant tension on the passing sutures during screw insertion.1 Screw breakage during insertion has been reported with bioabsorbable screws in as many as 10% of cases.4,5 Steps to minimize such a complication

76 CHAPTER

Robert H. Brophy Robert G. Marx

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Anterior Cruciate Ligament Reconstruction

FIG. 76-1 A, Anteroposterior and, B, lateral X-rays and C, axial, D, coronal, and, E, sagittal computed tomography scans demonstrating a malplaced, intraarticular femoral screw.

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(Continued)

Hardware Complications After Anterior Cruciate Ligament Reconstruction

76

FIG. 76-1—Cont’d

include use of a dilator device to create a pilot hole for screw insertion, maintenance of continuous pressure on the screwdriver to keep it fully seated, and use of a screw 1 mm smaller than the diameter of the tunnel.6 Postoperative complications include intraarticular placement of hardware, which may not be recognized at the time of surgery and can present clinically after the index procedure. A second procedure may be necessary to reposition or remove the misplaced hardware. Late screw breakage8–12 and delayed intraarticular migration of interference screws13–16 have also been described in the literature. Late migration of interference screws is rare but should be considered in the case of sudden pain in the late postoperative period after ACL reconstruction and, in the case of a metallic screw, can easily be evaluated with plain films. If such a complication is encountered, removal is mandated to minimize mechanical problems and cartilage damage.9,14,17 An arthroscopic approach is preferred,17 even if the screw is in the notch or popliteal fossa, although an arthrotomy may be required.15

ENDOBUTTON The Endobutton is another widely used fixation device that has been associated with specific complications. The Endobutton may remain in the femoral tunnel rather than flipping outside of the tunnel to rest on the lateral femoral cortex18 (Fig. 76-2). Conversely, the Endobutton may be pulled too far off the femoral cortex into the overlying soft tissue19

FIG. 76-2 A, Lateral and, B, anteroposterior X-rays show the Endobutton is in the femur and is not extracortical, indicating it has not flipped outside of the bone and is not supporting the graft.

587

Anterior Cruciate Ligament Reconstruction (Fig. 76-3). To ensure that the Endobutton has flipped and is in the correct position, the femoral tunnel length should be overdrilled by 6 mm and the graft should be marked at a location 6 mm distal to the desired insertion level.18 Once the Endobutton has flipped, the surgeon should feel for the button flipped on the lateral side of the femur against the cortex by pulling on the sutures. The surgeon can then pull back on the graft from below and pull both Endobutton sutures to make sure the button is not flipping with tension on the graft from the tibial side. If there is any doubt as to the position of the Endobutton, intraoperative fluoroscopy or x-rays should be used to confirm proper placement.19 Postoperatively, Muneta et al20 described late detachment and intraarticular migration of an Endobutton that had been fixed in the suprapatellar pouch, most likely due to impingement between the patella and femoral groove. To avoid this impingement and possible inflammatory reaction, it is preferable not to affix the Endobutton in the joint, particularly near the patellofemoral joint.20

CROSS-PIN FIXATION Cross pin fixation is a relatively new method used for tendon– bone fixation with the hope of improving on the problems with interference screw and Endobutton fixation methods. As with all new surgical methods and devices, a learning curve exists, with the potential for new problems as the technology becomes more widely adapted. Intraoperative complications with cross-pin fixation include lack of pin convergence and pin breakage. A number of postoperative complications associated with cross-pin fixation have recently been described in the literature. Incorrect placement, including leaving the pin proud on the lateral side of the femur as well as advancing the pin too far to penetrate the medial cortex of the femur, should be avoided as it may require reoperation for hardware removal21 (Fig. 76-4). The pin can break even after graft incorporation.22 The case of late breakage reported by Han et al22 using the Rigidfix system (Mitek Products, Norwood, MA) was attributed to an improper femoral tunnel with posterior wall blowout and posterior direction of the crosspins, potentially leading to abnormally high stress on the pins. Iliotibial band syndrome has also been described, either from direct irritation23 or in association with breakage of the femoral bioabsorbable cross-pin, specifically BioTransfix (Arthrex, Naples, FL).24

TIBIA FIXATION A number of options can be used for cortical fixation in the tibia, including interference screws and staples. Although early studies indicated a high incidence of hardware removal from the tibia due to pain when using interference screws,23,25,26 low-profile interference screws are usually well tolerated.27 Another option for tibial fixation when using hamstring grafts or Achilles allografts is a cortical screw with a spiked washer. Although one series using a higher-profile, round-headed screw reported a 70% incidence of hardware removal due to pain,28 other studies reviewing lower-profile screws suggest a very low, almost negligible, rate of hardware removal with this type of fixation.27,29 Staples are another method of fixation, used for supplementary fixation more often than primary fixation. The major concern with staples is their high profile and the resulting incidence (as high as 29%) of kneeling pain leading to hardware removal.30

SKELETALLY IMMATURE PATIENTS FIG. 76-3 The Endobutton is free in the soft tissues and is not providing support to the graft.

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Graft fixation in skeletally immature patients has its own potential for complication regardless of the type of fixation device used. The primary concern is disruption of the

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FIG. 76-4 Case 1: A, Coronal and, B, axial magnetic resonance imaging (MRI) demonstrates proud cross-pin laterally. Case 2: C, Axial MRI demonstrates proud cross-pin medially. In both cases the soft tissues were irritated, causing symptoms and requiring reoperation. (Reprinted from Marx R, Spock CR. Complications following hamstring anterior cruciate ligament reconstruction with femoral cross-pin fixation. Arthroscopy 2005;21:762.)

growth plates, which can manifest itself in a number of different ways including limb length discrepancy,31,32 tibial recurvatum,33 and valgus deformity of the distal femur.33,34 Specific recommendations with regard to fixation include avoidance of fixation hardware across the lateral distal

femoral epiphysis and tibial tubercle apophysis.33 Although this complication reflects the surgical approach and technique as much as the type of graft fixation, it is important to attempt to avoid or at least minimize disruption of the growth plate(s) whenever possible. 589

Anterior Cruciate Ligament Reconstruction TABLE 76-1 Potential Complications of Graft Fixation Devices Device

Site

Timing

Interference

Femur Intraoperative Laceration of passing suture

screw

Potential Complications

Advancement of graft within the tunnel Graft laceration/rupture Fracture of graft–bone plug Screw breakage Delayed

Screw breakage Intraarticular migration

Tibia

Intraoperative Screw breakage Delayed

Endobutton

Painful hardware

Femur Intraoperative Remains within femoral tunnel Advanced too far off femoral cortex in soft tissue Delayed

Detachment and intraarticular migration

Cross-pin

Femur Intraoperative Lack of pin convergence Pin breakage Delayed

Improper placement (proud lateral or medial) Pin breakage Iliotibial band syndrome

Staple

Tibia

Intraoperative Insufficient bite Delayed

Painful hardware

CONCLUSION In summary, each method of graft fixation presents its own potential complications both at the time of surgery and in the short- and long-term postoperative period (Table 76-1). Surgeons should be aware of the potential complications with the methods of fixation they use, how to avoid them, and how to treat them if they occur. Special considerations should be made in skeletally immature patients to minimize disruption of the growth place, with graft harvest, tunnel placement and drilling, and graft fixation.

References 1. Matthews LS, Soffer SR. Pitfalls in the use of interference screws for anterior cruciate ligament reconstruction: brief report. Arthroscopy 1989;5:225–226. 2. Arciero RA. Endoscopic anterior cruciate ligament reconstruction: complication of graft rupture and a method of salvage. Am J Knee Surg 1996;9:27–31. 3. Malek MM, Kunkle KL, Knable KR. Intraoperative complications of arthroscopically assisted ACL reconstruction using patellar tendon autograft. Instr Course Lect 1996;45:297–302.

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4. McGuire DA, Barber FA, Elrod BF, et al. Bioabsorbable interference screws for graft fixation in anterior cruciate ligament reconstruction. Arthroscopy 1999;15:463–473. 5. Pena F, Grontveldt T, Brown GA, et al. Comparison of failure strength between metallic and absorbable interference screws. Influence of insertion torque, tunnel-bone block gap, bone mineral density, and interference. Am J Sports Med 1996;24:329–334. 6. Smith CA, Tennent TD, Pearson SE, et al. Fracture of Bilok interference screws on insertion during anterior cruciate ligament reconstruction. Arthroscopy 2003;19:E4–6. 7. Cain EL Jr, Gillogly SD, Andrews JR. Management of intraoperative complications associated with autogenous patellar tendon graft anterior cruciate ligament reconstruction. Instr Course Lect 2003;52:359–367. 8. Bottoni CR, Deberardino TM, Fester EW, et al. An intra-articular bioabsorbable interference screw mimicking an acute meniscal tear 8 months after an anterior cruciate ligament reconstruction. Arthroscopy 2000;16:395–398. 9. Lembeck B, Wulker N. Severe cartilage damage by broken poly-Llactic acid (PLLA) interference screw after ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2005;13:283–286. 10. Macdonald P, Arneja S. Biodegradable screw presents as a loose intraarticular body after anterior cruciate ligament reconstruction. Arthroscopy 2003;19:E22–24. 11. Shafer BL, Simonian PT. Broken poly-L-lactic acid interference screw after ligament reconstruction. Arthroscopy 2002;18:E35. 12. Werner A, Wild A, Ilg A, et al. Secondary intra-articular dislocation of a broken bioabsorbable interference screw after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2002;10:30–32. 13. Bush-Joseph CA, Bach BR Jr. Migration of femoral interference screw after anterior cruciate ligament reconstruction. Am J Knee Surg 1998;11:32–34. 14. Hallet A, Mohammed A. Displaced femoral interference screw causing locked knee. Injury 2003;34:797–798. 15. Karlakki SL, Downes ME. Intra-articular migration of a femoral interference screw: open or arthroscopic removal. Arthroscopy 2003;19:E19. 16. Sidhu DS, Wroble RR. Intra-articular migration of a femoral interference fit screw. A complication of an anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:269–271. 17. Resinger C, Vecsei V, Heinz T, et al. The removal of a dislocated femoral interference screw through a posteromedial portal. Arthroscopy 2005;21:1398. 18. Karaoglu S, Halici M, Baktir A. An unidentified pitfall of Endobutton use: case report. Knee Surg Sports Traumatol Arthrosc 2002;10:247–249. 19. Simonian PT, Behr CT, Stechschulte DJ Jr, et al. Potential pitfall of the EndoButton. Arthroscopy 1998;14:66–69. 20. Muneta T, Yagishita K, Kurihara Y, et al. Intra-articular detachment of the Endobutton more than 18 months after anterior cruciate ligament reconstruction. Arthroscopy 1999;15:775–778. 21. Marx RG, Spock CR. Complications following hamstring anterior cruciate ligament reconstruction with femoral cross-pin fixation. Arthroscopy 2005;21:762. 22. Han I, Kim YH, Yoo JH, et al. Broken bioabsorbable femoral crosspin after anterior cruciate ligament reconstruction with hamstring tendon graft: a case report. Am J Sports Med 2005;33:1742–1745. 23. Clark R, Olsen RE, Larson BJ, et al. Cross-pin femoral fixation: a new technique for hamstring anterior cruciate ligament reconstruction of the knee. Arthroscopy 1998;14:258–267. 24. Pelfort X, Monllau JC, Puig L. Iliotibial band friction syndrome after anterior cruciate ligament reconstruction using the transfix device: report of two cases and review of the literature. Knee Surg Sports Traumatol Arthrosc 2006;14:586–589. 25. Howell SM, Deutsch ML. Comparison of endoscopic and two-incision techniques for reconstructing a torn anterior cruciate ligament using hamstring tendons. Arthroscopy 1999;15:594–606.

Hardware Complications After Anterior Cruciate Ligament Reconstruction 26. Siegel MG, Barber-Westin SD. Arthroscopic-assisted outpatient anterior cruciate ligament reconstruction using the semitendinosus and gracilis tendons. Arthroscopy 1998;14:268–277. 27. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146. 28. Jansson KA, Linko E, Sandelin J, et al. A prospective randomized study of patellar versus hamstring tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:12–18. 29. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar tendon graft and fixation type. Arthroscopy 2005;21:1202. 30. Hill PF, Russell VJ, Salmon LJ, et al. The influence of supplementary tibial fixation on laxity measurements after anterior cruciate ligament

31.

32. 33.

34.

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reconstruction with hamstring tendons in female patients. Am J Sports Med 2005;33:94–101. Andrews M, Noyes FR, Barber-Westin SD. Anterior cruciate ligament allograft reconstruction in the skeletally immature athlete. Am J Sports Med 1994;22:48–54. Lipscomb AB, Anderson AF. Tears of the anterior cruciate ligament in adolescents. J Bone Joint Surg 1986;68A:19–28. Kocher MS, Saxon HS, Hovis WD, et al. Management and complications of anterior cruciate ligament injuries in skeletally immature patients: survey of the Herodicus Society and The ACL Study Group. J Pediatr Orthop 2002;22:452–457. Koman JD, Sanders JO. Valgus deformity after reconstruction of the anterior cruciate ligament in a skeletally immature patient. A case report. J Bone Joint Surg 1999;81A:711–715.

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77 CHAPTER

R.P.A. Janssen*

Vascular Complications After Anterior Cruciate Ligament Reconstruction Vascular complications after anterior cruciate ligament (ACL) reconstructions cause serious morbidity and potential mortality. Fortunately, their incidence is low. Only a few peer-reviewed case reports provide information,1–5 and even a specific review article on complications after ACL surgery does not mention these rare complications.6 This chapter will be subdivided into discussions of arterial and venous complications after arthroscopic ACL reconstruction.

ARTERIAL COMPLICATIONS Knee arthroscopy is generally a safe procedure with a low incidence of complications. The two largest studies to date report complication rates of 0.54% and 0.8%.7,8 Penetrating popliteal artery injuries were described by DeLee in 6 of 118,540 arthroscopies.7 Small noted 9 cases (of 375,000 arthroscopic procedures) of penetrating trauma to the popliteal artery.8 A subsequent study of 8741 cases done by experienced arthroscopists showed no vascular complications.9 Pseudoaneurysm is the most frequently published popliteal artery lesion after arthroscopy of the knee. It is associated with direct violation of the posterior capsule or previous (open) knee surgery. However, it is still rare and published in case reports only.10–23 The incidence of arterial lesions after arthroscopic ACL reconstruction is unknown. * The author would like to thank J.B.A. van Mourik, MD, PhD, for his critical review in preparing this chapter.

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Five case reports have been published on various techniques of ACL reconstruction. Roth and Bray1 described an occlusion of the popliteal artery 7 cm proximal to the knee joint line. A composite graft, consisting of a polypropylene ligament augmentation and the middle third of the quadriceps patellar tendon, was used as ACL reconstruction and fixed to the lateral femur with a single staple in an over-the-top position. The patient had a burning pain in the foot 6 hours after surgery. Doppler signals of the pedal arteries were intact. The symptoms subsided. Dull aching at the posterior calf occurred at 3 weeks. Pain and dysesthesia in the foot recurred at 6 weeks. Angiography revealed the occlusion. The artery was trapped between the composite graft and the femur at surgical exploration. A saphenous bypass was performed. Spalding et al2 reported a case of unilateral claudication 8 years after ACL reconstruction with use of a GoreTex polytetrafluoroethylene braided ligament. Computed tomography (CT) analysis demonstrated a cyst had formed around the femoral insertion of the ruptured GoreTex ligament. The cyst was excised without the need for vascular repair. Evans et al3 reported a pseudoaneurysm of the medial inferior genicular artery following ACL reconstruction with a central third patellar tendon graft fixed with interference screws into the tibia and femur. It was detected at 5 weeks postsurgery with a 10-day history of pulsating swelling on the medial side of the knee with normal femoral, popliteal, and distal pulses. Diagnosis was made by contrast angiography. Ligation

Vascular Complications After Anterior Cruciate Ligament Reconstruction of the artery and removal of the thrombus from the pseudoaneurysm led to an excellent recovery. The cause of the lesion was elevation of the periosteum on the medial side of the tibia for tibial tunnel preparation. Aldridge et al4 described an avulsion of the middle genicular artery after arthroscopic ACL reconstruction with a bone–patellar tendon–bone (BPTB) autograft fixed with interference screws in both the tibia and femur. After tourniquet release, serious hemorrhage was detected with absent dorsal pedal pulse and a cold foot. The patient had a history of intravenous contrast dye allergy; therefore a CO2 arteriogram was performed with no evidence of vascular injury. The symptoms resolved overnight. At 2 weeks, the patient experienced difficulty with knee extension and felt a mass in the popliteal fossa. No mass was felt at examination, and pedal pulses were normal. Ultrasound examination showed no sign of venous thrombosis. At 4 weeks, a palpable mass in the fossa with 30-degree flexion contracture of the knee led to hospital readmission. Contrast angiography showed the vascular lesion. Surgical exploration revealed a tear in the popliteal artery, which was repaired with a short running stitch after removal of the hematoma. There was no rupture of the posterior capsule, and the avulsion of the middle genicular artery was hypothesized to have occurred during débridement of the femoral ACL stump. In our own consecutive series of 625 hamstring graft arthroscopic ACL reconstructions (1998–2005), three arterial complications occurred. In this series, the quadruple hamstring graft is fixed with a Bone Mulch Screw on the femoral side and a WasherLoc device in the tibia (rationale and surgical technique according to S.M. Howell; fixation devices by Arthrotek). The latter is a spiked washer with bicortical screw fixation. Our first case was a 44-year-old male with a previous history of open medial and lateral ligament repair of the same knee 15 years previously (motor vehicle accident). The hospital recovery was uneventful after ACL reconstruction. On day 17 postsurgery, he experienced pain and swelling in the popliteal fossa of the knee. The complaints partially resolved with physiotherapy. Two days later, the fossa pain returned with alterations of skin color, sensory loss, and an increasingly cold foot. Adequate dorsal pedal and posterior tibial pulses were noted. Duplex ultrasound examination showed no sign of venous thrombosis. Angiography revealed a subtotal occlusion of the popliteal artery at the level of the superior genicular artery (Fig. 77-1). An embolectomy was performed using a Fogarty catheter inserted in the femoral artery. The pedal pulses were diminished after embolectomy, and a second angiography was performed. The occlusion at the level of the popliteal artery was no longer detected. No further emboli were noted; however, the peripheral flow qualified as too slow and

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FIG. 77-1 Angiography of the right knee showing subtotal occlusion of the popliteal artery at the level of the superior genicular artery.

suggestive of small distal occlusions. Anticoagulant therapy with intravenous heparin as well an epidural analgesia were administered until complete recovery of peripheral circulation was attained. The patient developed a superficial infection of the groin wound, which was treated by antibiotics. He was mobilized and discharged after 8 days. Sensory loss of the foot slowly recovered after 4 months. Vascular analysis in rest and strenuous activity was performed at 4 months. He had no more complaints, a symmetrical ankle-brachial index in both legs, and intact pulses at the foot and ankle. Our hypothesis of the cause was the traumatic knee dislocation 15 years previously. Precursors could have been preexistent intimal vascular damage or adhesions of the artery at the level of the superior genicular artery in combination with the use of the tourniquet. We have previously published our second case of pseudoaneurysm of the popliteal artery due to damage by the bicortical tibial drill.5 A 24-year-old man had an ACL reconstruction using a quadruple hamstring graft. The patient was allowed full weight bearing, and an aggressive rehabilitation was started the day after surgery. The hospital stay was 593

Anterior Cruciate Ligament Reconstruction

FIG. 77-2 Sagittal computed tomography (CT) angiography of the right knee showing pseudoaneurysm of the popliteal artery near the tip of the bicortical tibial screw. (Reproduced with permission from Janssen RPA, Scheltinga MRM, Sala HAGM: Pseudoaneurysm of the popliteal artery after anterior cruciate ligament reconstruction with bicortical tibial screw fixation. Arthroscopy 2004;20:E4–E6.)

uneventful. Twelve days after surgery, the patient complained of progressive pain in the popliteal fossa that had started on day 5 postsurgery. On physical examination, a pulsating mass was felt in the popliteal fossa and there was a sensory loss of the medial foot as well as the plantar heel. The dorsal pedal and posterior tibial pulses were intact. Duplex analysis and CT angiography demonstrated a pseudoaneurysm of the infragenicular popliteal artery near the site of the bicortical tibial screw (Fig. 77-2). The pseudoaneurysm measured 3.5  1.5 cm on the sagittal view and 3.5  4 cm in the frontal aspect (Figs. 77–3 and 77–4). Surgical exploration was immediately performed. A vascular defect (3 mm) of the infragenicular popliteal artery was found just proximal to the origin of the anterior tibial artery (Fig. 77-5). However, the tip of the bicortical screw was not in direct contact with the arterial lesion. Apparently the 3.2-mm drill used for the bicortical screw had caused perforation of the popliteal artery. An arteriotomy was performed, and an intimal lesion was repaired. A venous patch was used to close the arterial defect. A Fogarty catheter was inserted to remove small clots present in the tibioperoneal trunk. Aspirin was prescribed for 3 months. No complications occurred after the vascular repair. Functional treatment using continuous passive motion (CPM) was started the day after surgery. The muscular and proprioceptive rehabilitation was initiated after wound healing occurred. At 4-month follow-up, there was full range of motion of 594

FIG. 77-3 Three-dimensional CT (3D-CT) angiography reconstruction of the right knee (posteromedial view) showing pseudoaneurysm of the popliteal artery near the tip of the bicortical screw.

FIG. 77-4 3D-CT reconstruction of the right knee (dorsal view) with subtraction of popliteal artery and pseudoaneurysm demonstrating exit point of femoral Bone Mulch Screw and tibial bicortical screw.

the knee. Lachman and anterior drawer test were 0 to 2 mm (according to International Knee Documentation Committee [IKDC]) with an absent pivot-shift test. Neurological evaluation by a neurologist showed a sensory loss of the saphenous and medial plantar nerves and, to a lesser degree, sensory loss of the superficial peroneal nerve of the right leg. There was no

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FIG. 77-5 Posteromedial view of the right knee at surgery showing a 3-mm vascular defect of the popliteal artery at the origin of the pseudoaneurysm. (Reproduced with permission from Janssen RPA, Scheltinga MRM, Sala HAGM: Pseudoaneurysm of the popliteal artery after anterior cruciate ligament reconstruction with bicortical tibial screw fixation. Arthroscopy 2004;20:E4–E6.)

loss of motor function. The dorsal pedal and posterior tibial pulses were intact. Our most recent case was a 50-year-old woman with a pseudoaneurysm of the popliteal artery after ACL reconstruction. She was seen 1 week postsurgery with pain in the popliteal fossa, absent foot pulses and sensory loss in the foot. Doppler examination showed weak signals in the foot. MRI angiography revealed a pseudoaneurysm of the supragenicular popliteal artery and a 4-cm occlusion proximal to the tibioperoneal trunk (Fig. 77-6). Surgical exploration on postsurgery day 9 showed damage to the artery in line with the tibial bicortical screw. Just as in our previous case, the tip of the bicortical screw was not in direct contact with the artery. The drill used for the bicortical screw had caused perforation of the popliteal artery. There was no hematoma around the pseudoaneurysm, nor was it in line with the Bone Mulch Screw fixation of the femur. The vascular surgeon thought this lesion to be preexistent and not related to the ACL surgery. The pseudoaneurysm was ligated and a saphenous bypass performed. A 5-day course of intravenous heparin was administered in combination with aspirin. Aspirin was continued after discharge. Follow-up is now 3 months; sensory loss of the plantar foot and decreased motor function of the flexor hallucis longus muscle are still present. Post et al24 studied the relative position of the neurovascular structures at risk when drilling bicortical screws for tibial fixation in ACL reconstruction. Arthroscopic tibial tunnels were placed in cadaver human knees using lateral roentgen graphs for accurate positioning. A 4.5-mm bicortical drill hole was placed perpendicular to the tibial surface, 1 cm distal to the tibial tunnel. The distances from the posterior tibial drill exit point to the nearby neurovascular

FIG. 77-6 Magnetic resonance imaging (MRI) angiography of the right leg showing pseudoaneurysm of the supragenicular popliteal artery and a 4-cm occlusion of the distal popliteal artery.

structures were measured with a caliper. The closest structure to the exit point was the bifurcation of the popliteal artery/vein (11.4  0.6 mm). The next closest was the anterior tibial vein (11.7  1.6 mm). The closest any individual hole came to a neurovascular structure was 3.5 mm from the anterior tibial vein. The researchers concluded that bicortical screw and spiked washer fixation of soft tissue ACL grafts appears to be relatively safe.24 Variations in anatomy and surgical technique are possible, and care should be taken in drilling through the posterior cortex. Possible recommendations to prevent neurovascular damage in drilling bicortical tibia screws are the use of a drill stop5 or directing the screw toward the fibular head instead of the posterior cortex.25 A single cortex fixation on the tibia is another possible safeguard without compromising stability of fixation.26 All cases show a certain delay in diagnosis (2–6 weeks postsurgery to 8 years). Damage to the popliteal artery can occur even with an all-inside technique of arthroscopic ACL reconstruction and fixation as well as with any type of graft. Other than the GoreTex rupture ligament case,2 all patients maintained adequate ACL stability after vascular surgery. The neurological deficits, however, may be permanent.

Conclusion The incidence of arterial complications after arthroscopic ACL reconstruction is 0.5% in our own consecutive series. A high level of suspicion, with clinical symptoms of painful 595

Anterior Cruciate Ligament Reconstruction pulsating mass and sensory deficits in the lower leg and foot, is mandatory in detecting these potentially devastating lesions. The differential diagnosis should include compartment syndrome and deep venous thrombosis. Doppler examination and intact dorsal pedal and posterior tibial pulses are unreliable in diagnosing arterial lesions after ACL reconstruction. Contrast CT and MRI angiography are the diagnostic tools of choice. Surgical exploration and vascular repair (or ligation/embolization of the feeding vessel) remain standard management. An immediate surgical exploration is imperative in limiting neurological damage.

VENOUS COMPLICATIONS The incidence of deep vein thrombosis (DVT) in orthopaedic surgery is amongst the highest in clinical practice. DVT is complicated by pulmonary embolism (PE) and the postthrombotic syndrome. The former may be fatal in its immediate course and may result in pulmonary hypertension in the long term. The latter affects 23% of limbs 2 years after DVT, 35% to 69% at 3 years, and 49% to 100% at 5 to 10 years.27 A recent meta-analysis of DVT after knee arthroscopy without thromboprophylaxis showed an overall DVT rate of 9.9% (3.1% to 17.9%) when routine screening using ultrasound or contrast venography is used. The proximal DVT rate is 2.1% (0% to 4.9%).28 The range of incidence among different studies is mainly related to two factors: (1) heterogenous groups of variable age, risk factors, and types of surgery and (2) variable experience of ultrasound technologists in detecting DVT in comparable populations.27 Delis et al27 found 50% of the DVT patients to be completely asymptomatic. Lohman sign and thigh circumference measurements were unreliable. They also examined the history of DVT if treated (aspirin in calf DVT, heparinwarfarin in proximal DVT). Following early diagnosis, total clot lysis was documented in 50% and partial clot lysis in the remaining 50% within 118 days median follow-up. Segmental venous reflux developed in at least 75% of the legs sustaining thrombosis. A previous thrombosis or the presence of two or more risk factors for thromboembolism significantly increased the incidence of DVT. No symptoms or signs of PE were documented.27 Geerts et al reviewed the evidencebased literature for thromboprophylaxis. They suggest not using thromboprophylaxis in knee arthroscopy, other than early mobilization. For patients undergoing arthroscopic knee surgery who are at higher than usual risk based on preexisting venous thromboembolic risk factors or following a prolonged or complicated procedure, they suggest thromboprophylaxis with low-molecular-weight heparin (Grade 2B level of evidence).29 The authors do not present further definitions of

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their suggestions or specific guidelines for thromboprophylaxis after ACL reconstructions. The incidence of DVT in ACL reconstruction has been prospectively analyzed with duplex ultrasound by Cullison et al.30 They found an incidence of DVT of 1.5% without thromboprophylaxis. However, one must note their selected population: all male (no previous surgery) with an average age of 26.5 years (the oldest patient is 39 years old). Their data cannot be extrapolated to a female population or patients with DVT risk factors or previous surgery. Hirota et al31 quantified pulmonary emboli after tourniquet release in patients undergoing ACL reconstruction (extramedullary procedure) versus total knee arthroplasty (intramedullary procedure). They chose these two groups to have more than 60 minutes of tourniquet time. This period was found to significantly increase the risk for DVT according to Demers et al.32 Hirota et al detected pulmonary emboli in all patients after release of the tourniquet using transesophageal echocardiography with a peak at 30 to 40 seconds postrelease. The amount of emboli formed was defined as %Ae (percentage of total emboli formed to the right atrial area). The atrial emboli percentage returned to baseline levels 2 minutes after tourniquet release in the ACL group. They found a significant linear correlation between the atrial emboli percentage and the duration of tourniquet inflation in the ACL group. In comparison, the total knee arthroplasty group had a significant larger atrial emboli percentage (four- to fivefold) with no return to baseline levels during the assessment period. No patient in either group showed signs of PE.31 Pulmonary emboli occur in all patients with ACL reconstructions after tourniquet release. In addition, PE may occur as a result of proximal DVT.33 No incidence is known for PE after ACL reconstruction. In our own consecutive series of 625 hamstring graft arthroscopic ACL reconstructions (1998–2005), one fatal PE is documented (incidence 0.2%). The patient was a 19year-old woman who used oral anticontraceptives. She suffered an ACL rupture 8 month previously in a soccer match. Arthroscopy had been performed 6 months previously at another institution. No complication occurred at the time. A conservative therapy for the knee instability was initiated. She was referred to our clinic due to persistent instability in daily activities. An ACL reconstruction was performed. There were no other intraarticular lesions. The patient was allowed full weight bearing, and an aggressive rehabilitation was started the day after surgery. During the 3-day hospital stay, thromboprophylaxis was given by means of low-molecular-weight heparin. The prophylaxis was discontinued at the time of discharge. The hospital recovery was uneventful. Eleven days postsurgery, she complained of increasing pain in the left medial upper leg. She was seen by a family

Vascular Complications After Anterior Cruciate Ligament Reconstruction physician on call. She was encouraged to continue her physiotherapy sessions. Massage of the leg was additionally undertaken. On day 12 postsurgery, she dropped to the ground at her front door and complained of serious shortness of breath. She was transported by ambulance to the nearest hospital. She was resuscitated during transport. A massive pulmonary embolus was diagnosed and streptokinase therapy initiated. She died the next day. Postmortem analysis showed a proximal DVT as well as a probable protein S deficiency. This was concluded after analysis of her relatives; a protein S deficiency was diagnosed in her sister. In this case, the fatal PE was due to a combination of factors: a preexistent coagulopathy, oral contraceptive medication, surgery, and failure to recognize DVT.

Conclusion DVT and PE are the only reported venous complications after ACL reconstruction. The incidence of fatal PE in our series is 0.2%. Despite the scientific effort to date, no recommendations for thromboprophylaxis in ACL reconstruction can be provided. Further investigation is required to analyze actual incidence and severity of venous thromboembolism as well as the efficacy-to-bleeding tradeoff for thromboprophylaxis after ACL reconstruction.

References 1. Roth JH, Bray RC. Popliteal artery injury during anterior cruciate ligament reconstruction: brief report. J Bone Joint Surg 1988;70B:840. 2. Spalding TJW, Botsford DJ, Ford M, et al. Popliteal artery compression: a complication of Gore-tex anterior cruciate ligament reconstruction. J Bone Joint Surg 1996;78B:151–152. 3. Evans JD, Boer de MT, Mayor P, et al. Pseudoaneurysm of the medial inferior genicular artery following anterior cruciate ligament reconstruction. Ann R Coll Surg Engl 2000;82:182–184. 4. Aldridge JM III, Weaver JP, Mallon WJ. Avulsion of the middle genicular artery: a previously unreported complication of anterior cruciate ligament repair. A case report. Am J Sports Med 2002;30:748–750. 5. Janssen RPA, Scheltinga MRM, Sala HAGM. Pseudoaneurysm of the popliteal artery after anterior cruciate ligament reconstruction with bicortical tibial screw fixation. Arthroscopy 2004;20:E4–E6. 6. Allum R. Aspects of current management. Complications of arthroscopic reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2003;85B:12–16. 7. DeLee JC. Complications of arthroscopy and arthroscopic surgery: results of a national survey. Arthroscopy 1985;1:214–220. 8. Small NC. Complications in arthroscopic surgery: the knee and other joints. Arthroscopy 1986;2:253–258. 9. Small NC. Complication in arthroscopic surgery performed by experienced arthroscopists. Arthroscopy 1988;4:216–221.

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10. Beck DE, Robinson JG, Hallet JW. Popliteal artery pseudoaneurysm following arthroscopy. J Trauma 1986;26:87–89. 11. Manning MP, Marshall JH. Aneurysm after arthroscopy. J Bone Joint Surg 1987;69:151. 12. Vincent GM, Stanish WD. False aneurysm after arthroscopic meniscectomy. A report of two cases. J Bone Joint Surg 1990;72:770–772. 13. Armato DP, Czamecki D. Geniculate artery pseudoaneurysm: a rare complication of arthroscopic surgery. Am J Roentgenol 1990;155:659 (letter). 14. Guy RJ, Spalding TJ, Jarvis LJ. Pseudoaneurysm after arthroscopy of the knee. A case report. Clin Orthop Rel Res 1993;295:214–217. 15. Ritt MJ, Te Slaa RL, Koning J, et al. Popliteal pseudoaneurysm after arthroscopic meniscectomy. A report of two cases. Clin Orthop Relat Res 1993;295:198–200. 16. Hilborn M, Munk PL, Miniaci A, et al. Pseudoaneurysm after therapeutic knee arthroscopy: imaging findings. Am J Roentgenol 1994;163:637–639. 17. Aldrich D, Anschuetz R, Lopresti C, et al. Pseudoaneurysm complicating knee arthroscopy. Arthroscopy 1995;11:229–230. 18. Potter D, Morris-Jones W. Popliteal artery injury complicating arthroscopic meniscectomy. Arthroscopy 1995;11:123–126. 19. Sarrosa EA, Ogilvie-Harris DJ. Pseudoaneurysm as complication of knee arthroscopy. Arthroscopy 1997;13:644–645. 20. Carlin RE, Papenhausen M, Farber MA, et al. Sural artery pseudoaneurysms after knee arthroscopy: treatment with transcatheter embolization. J Vasc Surg 2001;33:170–173. 21. Mullen DJ, Jabaji GJ. Popliteal pseudoaneurysm and arteriovenous fistula after arthroscopic meniscectomy. Arthroscopy 2001;17:E1. 22. Kiss H, Drekonja T, Grethen C, et al. Postoperative aneurysm of the popliteal artery after arthroscopic meniscectomy. Arthroscopy 2001;17:203–205. 23. Audenaert E, Vuylsteke M, Lissens P, et al. Pseudoaneurysm complicating knee arthroscopy. A case report. Acta Orthop Belg 2003;69:382–384. 24. Post WR, King SS. Neurovascular risk of bicortical drilling for screw and spiked washer fixation of soft-tissue anterior cruciate ligament graft. Arthroscopy 2001;17:244–247. 25. Howell SM. Personal correspondence, 2005. 26. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146. 27. Delis KT, Hunt N, Strachan RK, et al. Incidence, natural history and risk factors of deep vein thrombosis in elective knee arthroscopy. Thromb Haemost 2001;86:817–821. 28. Ilahi OA, Reddy J, Ahmad I. Deep venous thrombosis after arthroscopy: a meta-analysis. Arthroscopy 2005;21:727–730. 29. Geerts WH, Pineo GF, Heit JA, et al. Prevention of venous thromboembolism. The seventh ACCP conference on antithrombotic and thrombolytic therapy. Chest 2004;126:338S–400S. 30. Cullison TR, Muldoon MP, Gorman JD, et al. The incidence of deep venous thrombosis in anterior cruciate ligament reconstruction. Arthroscopy 1996;12:657–659. 31. Hirota K, Hashimoto H, Tsubo T, et al. Quantification and comparison of pulmonary emboli formation after pneumatic tourniquet release in patients undergoing reconstruction of anterior cruciate ligament and total knee arthroplasty. Anest Analg 2002;94:1633–1638. 32. Demers C, Marcoux S, Ginsberg JS, et al. Incidence of venographically proved deep vein thrombosis after knee arthroscopy. Arch Intern Med 1998;158:47–50. 33. Williams JS, Hulstyn MJ, Fadale PD, et al. Incidence of deep vein thrombosis after arthroscopic knee surgery: a prospective study. Arthroscopy 1995;11:701–705.

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78 CHAPTER

Kai Mithoefer Thomas J. Gill

Fracture Complications After Anterior Cruciate Ligament Reconstruction Anterior cruciate ligament (ACL) reconstruction is one of the most frequently performed operative procedures with more than 100,000 reconstructions performed annually in the United States alone.1 Autogenous bone–patellar tendon–bone (BPTB) presents the most frequently used graft choice by orthopaedic surgeons in the United States, Canada, and Europe.2 This procedure includes creation of large bony defects in the tibia, femur, and patella for graft harvesting and fixation.2,3 The effects of bony defects on bone strength have become a major concern in orthopaedic trauma surgery, and their relevance in the development of postoperative fracture after ACL reconstruction is increasingly recognized.4,5 Complications have been reported to occur in 1.8% to 24% of ACL reconstructions.6–8 Serious complications after ACL reconstruction include arthrofibrosis, donor site pain, patella tendinitis, patella tendon rupture, and avascular necrosis of the femoral condyles. Fracture following ACL reconstruction presents a devastating complication that may involve the tibia, patella, or femur.

FEMUR FRACTURE Femur fracture following ACL reconstruction has been reported in isolated cases as a result of distal femoral bone defects created for extraarticular fixation of a GoreTex prosthetic graft,9 a ligament augmentation device,10 iliotibial band tenodesis,11 or femoral post fixation.12 Supracondylar femur fracture after arthroscopic ACL 598

reconstruction without intraoperative complications or use of supplemental fixation has also been reported.13,14 Fracture of the femoral diaphysis has also been described after ACL reconstruction and was caused by multiple perforations of the Beath pin trough’s femoral metaphyseal– diaphyseal junction.15 Although femur fractures are reported with increasing frequency after ACL reconstruction, this complication is likely underreported and its exact incidence is not known. Physical examination in patients with this complication always produces marked tenderness, muscular guarding, bony crepitation, and a large effusion. Plain radiographs and computed tomography (CT) scans are helpful to identify the fracture pattern and will often show that the fracture occurred through the intraosseous tunnel created in the posterior distal femur. CT scans may demonstrate increased bone tunnel diameter (Fig. 78-1). Several factors predispose the anatomical area of the femoral tunnel to developing a distal femur fracture after arthroscopic ACL reconstruction. The presence of the large femoral tunnel likely acts as a predisposing factor due to the localized stress-rising effect of the bony defect.16–20 This effect results from a concentration of local stresses around the femoral defect and reduced energy-absorbing capacity from the decreased amount of bone available to withstand the applied load.17 Because bone with stress concentration behaves in a more brittle fashion, the increased local stresses can reach the ultimate stress of the bone at much lower applied loads.19 Depending

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FIG. 78-1 A and B, Plain radiographs of the distal left femur demonstrating supracondylar femur fracture after anterior cruciate ligament reconstruction. C, Computed tomography demonstrating fracture through the intraosseous femoral tunnel. D and E, Postoperative radiographs 12 months after open reduction internal fixation with a locking condylar plate. (From Mithoefer K, Gill TJ, Vrahas MS. Supracondylar femoral fracture after arthroscopic reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2005;87A:1591–1596.) (Continued)

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FIG. 78-1—Cont’d

on the geometry of the defect, strength reductions of 20% to 90% may occur.18,19 Insertion of allogenic or autogenous bone graft into the defect, such as in BPTB ligament reconstruction, has not been shown to significantly change the mechanical weakening of the bone.19 The combination of greater localized stresses and decreased load-absorbing capacity predisposes the area of the defect to failure. Aside from the bony defect, additional stress concentration in the distal femur results from the change in the bony moment of inertia due to the acute change of sagittal, axial, and coronal geometry of the posterior condylar flare and intercondylar notch.18,19 The bony geometry of the distal femur has been found to play a critical role in the structural properties and prediction of fracture load.21,22 Geometric analysis of the distal femur has shown the thinnest cortical shell to be in the posterior aspect of the distal femur,23 therefore predicting the lowest fracture load in the anatomical region of the femoral tunnel. Decreased bone mineral density of up to 20% has been observed after knee ligament injury and may also 600

contribute to the increased fracture risk after ACL reconstruction due to decreased bending strength in the distal femur.22,24 Bone bruising of the lateral femoral condyle, which is frequently associated with ACL rupture, may also compromise the biomechanical properties in the lateral femoral condyle and predispose to earlier failure of the bruised bone.25 When the area of the bony defect is subjected to tensile stress, as with extension trauma to the knee, the load strength of the already vulnerable posterior distal femur is even further reduced.17,18 However, because the bone in this anatomical region is predominantly under compression, the likelihood of fracture development and crack propagation is decreased. This may explain why femur fracture does not occur more frequently after arthroscopic ACL reconstruction. Because bony remodeling has been shown to decrease stress concentration around bony defects after 8 to 12 weeks,18 this would be expected to decrease the predisposition for femur fracture after ACL reconstruction. However, bone

Fracture Complications After Anterior Cruciate Ligament Reconstruction tunnel healing of the femoral tunnel has been shown to be delayed by the exposure to biological factors from the joint.26 A previous report demonstrating fracture through the femoral tunnel 2 years after ACL reconstruction27 suggests that the stress concentration effect of the femoral tunnel continues for a prolonged period after surgery. Bone tunnel enlargement after ACL reconstruction is well documented and occurs in as many as 68% of cases after ACL reconstruction. The etiology of this clinical phenomenon is not completely understood, but it is thought to be related to a combination of multiple biological and mechanical factors. A better understanding of the clinical relevance of bone tunnel enlargement is still evolving.28 Previous experimental studies have shown that the breaking strength of bone decreases in direct proportion to the size of a bony defect.16 Based on these findings, enlargement of the femoral tunnel may have clinical relevance for the development of supracondylar femur fracture after ACL reconstruction by further decreasing the mechanical fracture resistance. Bone tunnel enlargement has also been suggested to increase the risk for tibial plateau fracture after ACL reconstruction.5,29 Given the frequency of ACL reconstruction and high incidence of bone tunnel enlargement, the potential predisposing effect of this phenomenon for fracture of the distal femur needs to be further examined. During ACL reconstruction, a tunnel is drilled into the distal femur for subsequent graft fixation. Femoral tunnel placement is performed arthroscopically in accordance with recent technique recommendations.2,3 To optimize graft positioning, the femoral tunnel is placed as far posterior as possible while carefully avoiding disruption of the posterior cortex. This is commonly achieved by the use of a femoral tunnel placement guide with built-in offset that maintains a 1- to 2-mm-thick posterior cortical rim. Disruption of the posterior cortex can result from posterior placement of the femoral tunnel.7 This complication is different than fracture through the femoral tunnel. However, it should be carefully avoided because it may facilitate development of a fracture of the lateral femoral condyle12 (Fig. 78-2). ACL reconstruction using computerassisted navigation systems for tunnel placement or using a two-incision technique for ACL reconstruction may be able to reduce the risk for this complication.30 Anatomical open reduction is critical to avoid premature arthritis and may also be able to maintain the graft in the isometric position. Fracture fixation by interfragmentary screws, supracondylar blade plate, dynamic compression plate, and intramedullary nail has all been described9–12 after femur fracture following ACL reconstruction. Permanent loss of knee motion has been described in some cases after distal femoral fracture fixation.10,12,15 Early open reduction and internal fixation using condylar locking plates provide effective fracture fixation with limited soft tissue dissection and reduced postoperative morbidity and may allow for graft retention.13

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FIG. 78-2 Computed tomography (CT) image showing lateral femoral condyle fracture through the osseous tunnel following intraoperative posterior wall disruption. (From Manktelow AR, Haddad FS, Goddard NJ. Late femoral condyle fracture after anterior cruciate ligament reconstruction. Am J Sports Med 1998;26:587–590.)

A proactive treatment approach facilitates early recovery, full range of motion, excellent subjective knee rating, high functional outcome scores, and return to pivoting sports.13 Following anatomical fracture fixation, intraoperative stability testing may reveal a functional ACL graft without the need for revision ACL reconstruction. If anatomical fracture fixation does not maintain graft function, revision ACL reconstruction may be performed at the time of fracture fixation or at a later time.

PATELLA FRACTURE Patella fracture represents a devastating complication following ACL reconstruction using BPTB autograft and has been reported with an incidence of 0.2 to 0.8%.5,31,32 Patella fractures after ACL reconstruction are more frequently observed in women and older patients.33 These fractures can occur intraoperatively or postoperatively. Intraoperative fractures are very rare and most often result from technical errors such as harvesting too large a bone block. More frequently, injuries occur between 5 and 12 weeks postoperatively.31,32,34 These fractures in the early postoperative period are considered a major complication because they may interfere with graft remodeling and produce significant chondral damage and persistent anterior knee pain. Most fractures are transverse and occur at the proximal margin of the defect created during bone block harvesting35 (Fig. 78-3). The transverse fracture pattern usually results from indirect injuries to the patella, such as rapid eccentric contractions of the quadriceps muscle. Stellate and Y-type fracture patterns have been described 601

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FIG. 78-3 Lateral radiographic views (before [A] and after [B] fracture fixation) of a displaced transverse fracture of the patella after anterior cruciate ligament reconstruction. (From Stein DA, Hunt SA, Rosen JE, et al. The incidence and outcome of patella fractures after anterior cruciate ligament reconstruction. Arthroscopy 2002;18:578–583.)

after direct-impact injuries to the weakened patella.36 Longitudinal patella fractures may also occur from vertical troughs created by past-pointing with the saw blade. Patella fractures can be displaced or nondisplaced and may or may not be symptomatic.36,37 Most fractures cause a disturbance of the extensor mechanism and are easily diagnosed. However, silent nondisplaced patella fractures have been reported after ACL reconstruction as a cause of chronic anterior knee pain and long-term functional limitation.37 Multiple factors have been suggested to contribute to the development of this complication. Decreased vascularity to the central portion of the patella after graft harvest has been suggested to contribute to the risk for postoperative patellar fracture. The intraosseous blood supply of the patella is composed of the midpatellar, polar, and quadriceps tendon system.38 The disruption of these vessels during graft harvest can impair healing of the harvest site and may even affect the remaining normal bone. In knee flexion, the patella is subject to posterior forces along the superior and inferior poles and an opposing anterior force when the posterior surface of the patella 602

contacts the femur. This three-point bending force on the patella has been hypothesized to be the force that acts on the weakened patella, resulting in many of the indirect patella fractures that occur when the knee is flexed.39 Biomechanical studies have shown that the anterior cortex of the patella has the highest load resistance and that superior transverse cuts during graft harvest can reduce patellar resistance by 30% to 40%.31 The transverse bone cut has been shown to average more than 13 mm in width because of subtle motion of both the patella and the cutting instrument. Attention to surgical technique with smaller transverse bone cuts can help minimize the weakening effect on the anterior patellar cortex. Drill holes at the corners of the planned osteotomy can also be helpful to prevent past-pointing and undesired propagation of the bone defect beyond the outline of the osteotomy. Several authors have pointed out that the dimensions of the grafted bone plug should not exceed 9 to 10 mm in width. Using a 7-mm-wide sagittal blade and angling the blade can reduce the width of the true traversal cut. In addition to the width of the bone defect, its length and depth are important. Graft length of less than

Fracture Complications After Anterior Cruciate Ligament Reconstruction 50% to 66% of the patellar length is recommended with minimum graft length of 20 mm.40 Similarly, depth of the graft should not exceed one-third of the measured depth of the patella.41 Harvesting the BPTB graft acts as a significant stress riser on the patellar bone.42 This stress-rising effect is directly correlated with the size of the bone defect. Tapered bone defects cause less patellar stress concentration compared with square or trapezoidal defects but are still associated with significantly higher stress concentration than in the normal patella. Taking the larger trapezoidal bone plug from the tibia and a triangular plug from the patella has been suggested as a technique to reduce the patellar defect size and stress concentration.40,43 Packing the patella defect with cancellous bone grafts has been recommended by many authors.38,40–42,44–47 Bone grafting has been shown to decrease the stress-rising effect and can help to normalize the strength and resistance of the harvest site.44 Grafting the bony defect is particularly recommended for graft sites wider than 10 to 12 mm or deeper than 6 mm.38 In addition to graft size and shape, the grafting technique is also important. Use of a circular oscillating saw can create lower stresses on the corners, removes smaller grafts, and creates a rounded bottom of the trough.48 It has been theorized that some patella fractures after ACL reconstruction result from a weakened patella and abnormal patellar tracking due to a deconditioned quadriceps, which in turn increases the patellofemoral contact stresses. Early quadriceps conditioning and proprioceptive exercises decrease abnormal patellar positioning and tracking.5,31 Improved quadriceps strength and function may also help restore normal gait pattern and thereby prevent direct fractures from falls or from sudden uncoordinated muscle contraction. Nondisplaced fractures can be treated nonoperatively with rigid knee bracing. However, some authors advocate surgical fixation for all fractures because it restores the extensor mechanism and allows for immediate motion and rapid return to knee rehabilitation.31 We have successfully used cannulated screw fixation with figure-eight Fiberwire augmentation through the cannulated screws for these nondisplaced fractures. With appropriate treatment, minimal residual longterm consequences have been observed after patella fractures following ACL reconstruction with functional outcomes, comparable to patients without fracture complications.12,40

TIBIA FRACTURE Tibial Plateau Fracture To date, six reports have described tibial plateau fracture complicating ACL reconstruction4,29,49–52 (Fig. 78-4). The fractures occur between 7 and 18 months postoperatively

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and are frequently induced by torsional trauma. Examination typically reveals a significant effusion and notable crepitation. Plain radiographs and CT scans are diagnostic. In all described cases, the fracture of the tibial plateau occurred through the transosseous tibial tunnel. Although no biomechanical studies have specifically addressed the mechanical effect of tibial bone tunnels, the presence of the tibial tunnel likely acts as a predisposing factor because the cortical defect acts as a stress riser.17,20 It has been well documented that cortical defects can decrease resistance to torsional forces by as much as 90%.19,20 Stress concentration is known to occur in the region of the anterior starting point of the tibial tunnel from the sudden change of the anatomical geometry of the metaphyseal–diaphyseal junction of the tibia.17 Screw holes used for post and washer fixation of the tibial graft may further increase the stress concentration. Bone tunnel enlargement has also been suggested to increase the risk for tibial fracture after ACL reconstruction.5,51 Treatment of tibial plateau fractures after ACL reconstruction has been successfully achieved by nonoperative treatment for nondisplaced fractures50 or by open reduction and internal fixation.4,5,49 Less invasive fracture fixation (LISS) (Synthes, Paoli, PA) (see Fig. 78-4) has been described with minimal postoperative morbidity and early functional recovery.51 Depending on the ability of the fracture fixation to maintain the graft in the isometric position, revision ACL reconstruction may5 or may not be necessary.51

Tibial Tubercle Fracture Tibial tuberosity avulsion fractures have been described in rare cases of autograft BTB reconstructions.53–55 Tibial tubercle avulsion may occur ipsilaterally with primary ACL reconstruction or in the contralateral leg when using the contralateral patellar tendon autograft in revision cases. These injuries usually occur in the early postoperative period and have been described between the first postoperative day and 6 weeks postoperatively. The early occurrence of these injuries has been related to technical errors, early mechanical overload from aggressive postoperative weight bearing, and the combined stress-riser effect of the tibial bone plug harvest site and the tibial tunnel. Fractures may involve the entire tubercle or only a part of the tibial tuberosity. Patients commonly report a popping sensation with acute pain and associated inability or difficulty to extend the involved extremity. Radiographs are necessary to differentiate a tibial tubercle fracture from a patellar tendon avulsion, which can present with the same clinical findings (Fig. 78-5). Harvesting of the central part of the tibial tubercle graft creates a thin cancellous bone bridge between the graft site and tibial tunnel. The tibial cortical defects result in a significant stress concentration, particularly on the medial 603

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FIG. 78-4 Plain radiographs (A and B) and computed tomography (C) demonstrating tibial plateau fracture through the transosseous tibial tunnel after anterior cruciate ligament reconstruction. Plain radiograph (D) of the tibia at 6 months after fixation with limited invasive stabilization system (LISS). (From Mithoefer K, Gill TJ, Vrahas MS. Tibial plateau fracture following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:325–328.)

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References

FIG. 78-5 Lateral radiograph showing a minimally displaced tibial tuberosity fracture after tibial tubercle graft harvesting osteotomy. (From Busfield BT, Safran MR, Cannon WD. Extensor mechanism disruption after contralateral middle third patellar tendon harvest for anterior cruciate ligament revision reconstruction. Arthroscopy 2005;21:1268.)

aspect of the tibial tubercle. Undermining the medial or lateral insertion sites of the patellar tendon with the osteotome or oscillating saw causes further thinning of the bone bridge, which in some cases may lead to avulsion fractures. Undermining may result from a failure to account for the anatomical slope of the tibial tuberosity when making the bone cuts. Bone cuts perpendicular to the extremity axis lead to undermining, particularly of the lateral tibial tuberosity with its posterolateral slope. Sawing perpendicular to the tuberosity reduces the tendency to undermine the lateral tuberosity.53 Harvesting triangular bone blocks has also been proposed to minimize undermining and stress concentration.53 The use of round-cornered or trapezoidal bone cuts also helps minimize the stress-riser effect at the graft site. Lack of active knee extension and displacement of the fragment are indications for surgical fixation. The combination of interfragmentary screw fixation and tension band techniques provides rigid fixation that allows for immediate passive range-of-motion postoperatively and return of unrestricted knee function.53–55 In summary, fracture after ACL reconstruction is an infrequent but serious complication. Knowledge of the pathogenesis, risk factors, and specific anatomical and technical aspects that can lead to fracture complications after ACL reconstruction are important for the surgeon performing ACL reconstruction and can help prevent these devastating complications. Patients should be routinely counseled regarding these potential complications, particularly when BTB autograft is harvested.

1. Owings MF, Kozak LJ. Ambulatory and inpatient procedures in the United States, 1996. Vital Health Stat 1998;139:1–119. 2. Fineberg MS, Zarins B, Sherman OH. Practical considerations in anterior cruciate ligament replacement surgery. Arthroscopy 2000;16:715–724. 3. Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1997;79A:1556–1576. 4. Delcogliano A, Chiossi S, Caporaso A, et al. Tibial plateau fracture after arthroscopic anterior cruciate reconstruction. Arthroscopy 2001;17:E16. 5. Brownstein B, Bronner S. Patella fracture associated with accelerated ACL rehabilitation in patients with autogenous patella tendon reconstructions. J Orthop Sports Phys Ther 1997;26:168–172. 6. Small NC. Complications in arthroscopy: the knee and other joints. Arthroscopy 1986;2:253–258. 7. Graf B, Uhr F. Complications of intraarticular anterior cruciate reconstruction. Clin Sports Med 1988;7:835–848. 8. Hughston JC. Complications of anterior cruciate ligament surgery. Orthop Clin N Am 1985;16:237–240. 9. Ternes JP, Blasier RB, Alexander AH. Fracture of the femur after anterior cruciate ligament reconstruction with a GORE-TEX prosthetic graft. Am J Sports Med 1993;21:147–149. 10. Radler C, Wozasek GE, Seotz H, et al. Distal femoral fracture through the screw hole of a ligament augmentation device. Arthroscopy 2000;16:737–739. 11. Noah J, Sherman OH, Roberts C. Fracture of the supracondylar femur after anterior cruciate ligament reconstruction using patellar tendon and iliotibial tenodesis. Am J Sports Med 1992;20:615–618. 12. Berg EE. Lateral femoral condyle fracture after endoscopic anterior cruciate ligament reconstruction. Arthroscopy 1994;10:693–696. 13. Mithoefer K, Gill TJ, Vrahas MS. Supracondylar femoral fracture after arthroscopic reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2005;87A:1591–1596. 14. Wilson TC, Rosenblum WJ, Johnson DL. Fracture of the femoral tunnel after an anterior cruciate ligament reconstruction. Arthroscopy 2004;20:E45–E47. 15. Wiener DF, Siliski JM. Distal femoral shaft fracture: A complication of endoscopic anterior cruciate ligament reconstruction. Am J Sports Med 1996;24:244–247. 16. Bechtol CO, Lepper H. Fundamental studies in the design of metal screws for internal fixation of bone. J Bone Joint Surg 1956;38A:1385. 17. Brooks DB, Burstein AH, Franke VH. The biomechanics of torsional fractures: the stress concentration effect of a drill hole. J Bone Joint Surg 1970;52A:507–514. 18. Burstein AH, Currey J, Frankel VH, et al. Bone strength. The effect of screw holes. J Bone Joint Surg 1972;54A:1143–1156. 19. Johnson BA, Fallat LM. The effect of screw holes on bone strength. J Foot Ankle Surg 1997;36:446–451. 20. Clark CR, Morgan C, Sonstegard DA, et al. The effect of biopsy hole shape and size on bone strength. J Bone Joint Surg 1977;59:213–217. 21. Augat P, Reeb H, Claes LE. Prediction of fracture load at different skeletal sites by geometric properties of the cortical shell. J Bone Miner Res 1996;11:1356–1363. 22. Stromsoe K, Hoiseth A, Alho A, et al. Bending strength of the femur in relation to non-invasive bone mineral assessment. J Biomech 1995;28:857–861. 23. Guy P, Krettek C, Manns J, et al. CT-based analysis of the geometry of the distal femur. Injury 1998;29:C16–C21. 24. Sievanen H, Kannus P, Heinonen A, et al. Bone mineral density and muscle strength of lower extremities and long-term strength training, subsequent knee ligament injury and rehabilitation. Bone 1994;15:85–90.

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Anterior Cruciate Ligament Reconstruction 25. Johnson DL, Bealle DP, Brand JC, et al. The effect of geographic lateral bone bruise on knee inflammation after acute anterior cruciate ligament rupture. Am J Sports Med 2000;28:152–155. 26. Berg EE, Pollard ME, Kang Q. Intraarticular bone tunnel healing. Arthroscopy 2001;17:189–195. 27. Manktelow AR, Haddad FS, Goddard NJ. Late femoral condyle fracture after anterior cruciate ligament reconstruction. Am J Sports Med 1998;26:587–590. 28. Wilson TC, Kantaras A, Atay A, et al. Tunnel enlargement after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:543–549. 29. Thietje R, Faschingbauer M, Nurnberg HJ. Spontaneous fracture of the tibia after replacement of the anterior cruciate ligament with absorbable interference screws. A case report and review of the literature. Unfallchirurg 2000;103:594–596. 30. Koh J. Computer-assisted navigation and anterior cruciate ligament reconstruction: accuracy and outcomes. Orthopedics 2005;28: S1283–S1287. 31. Viola R, Vianello R. Three cases of patella fractures in 1320 anterior cruciate reconstructions with bone-patellar tendon-bone autograft. Arthroscopy 1999;15:93–97. 32. Papageorgiou CD, Kostopoulos VK, Moebius UG, et al. Patellar fractures associated with medial-third bone-patellar tendon-bone autograft ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:151–154. 33. Sharkey NA, Donahue SW, Smith TS, et al. Patellar strain and patellofemoral contact after bone-patellar tendon-bone harvest for anterior cruciate ligament reconstruction. Arch Phys Med Rehabil 1997;78:256–263. 34. Carreira DA, Fox JA, Freedman KB, et al. Displaced nonunion patellar fracture following use of a patellar tendon autograft for ACL reconstruction: case report. J Knee Surg 2005;18:131–134. 35. Steen H, Tseng KF, Goldstein SA, et al. Harvest of patellar tendon (bone-tendon-bone) autograft for ACL reconstruction significantly alters surface strain in the human patella. J Biomech Eng 1999;121:229–233. 36. Simonian PT, Mann FA, Mandt PR. Indirect forces and patella fracture after anterior cruciate ligament reconstruction with the patellar ligament. Am J Knee Surg 1995;8:60–65. 37. Morgan-Jones RL, Cross TM, Caldwell B, et al. “Silent” transverse patellar fracture following anterior cruciate ligament reconstruction. Arthroscopy 2001;17:997–999. 38. Benson ER, Barnett PR. A delayed transverse avulsion fracture of the superior pole of the patella after anterior cruciate ligament reconstruction. Arthroscopy 1998;14:85–88. 39. Carpenter JE, Kasman R, Matthews LS. Fractures of the patella. Instr Course Lect 1994;43:97–108. 40. Christen B, Jakob R. Fractures associated with patellar ligament grafts in cruciate ligament surgery. J Bone Joint Surg 1992;74B:617–619.

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41. Malek MM, Kunkle KL, Knable KR. Intraoperative complications of arthroscopically assisted ACL reconstruction using patellar tendon autograft. Instr Course Lect 1996;45:297–302. 42. Friis EA, Cooke FW, McQueen DA. Effect of bone block removal and patellar prosthesis on stresses in the human patella. Am J Sports Med 1994;22:696–701. 43. DuMontier TA, Metcalf MH, Simonian PT, et al. Patella fracture after anterior cruciate ligament reconstruction with the patellar tendon: a comparison between different shaped bone block excisions. Am J Knee Surg 2001;14:9–15. 44. Stein DA, Hunt SA, Rosen JE, et al. The incidence and outcome of patella fractures after anterior cruciate ligament reconstruction. Arthroscopy 2002;18:578–583. 45. Roberts TS, Drez D Jr, Parker W. Prevention of late patellar fracture in ACL deficient knees reconstructed with bone-patellar tendon-bone autografts. Am J Knee Surg 1989;2:83–88. 46. Daluga D, Johnson C, Bach BR Jr. Primary bone grafting following graft procurement for anterior cruciate ligament insufficiency. Arthroscopy 1990;6:205–208. 47. Ferrari JD, Bach BR Jr. Bone graft procurement for patellar defect grafting in anterior cruciate ligament reconstruction. Arthroscopy 1998;14:543–545. 48. Jackson DW, Cohn BT, Morrison DS. A new technique for harvesting the patella tendon in patients undergoing anterior cruciate ligament reconstruction. Orthopedics 1990;13:165–167. 49. El-Hage ZM, Mohammed A, Griffiths D, et al. Tibial plateau fracture following allograft anterior cruciate ligament (ACL) reconstruction. Injury 1998;29:73–74. 50. Morgan E, Steensen RN. Traumatic proximal tibial fracture following anterior cruciate ligament reconstruction. Am J Knee Surg 1998;11:193–194. 51. Mithoefer K, Gill TJ, Vrahas MS. Tibial plateau fracture following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2004;12:325–328. 52. Sundaram RO, Cohen D, Barton-Hanson N. Tibial plateau fracture following gracilis-semitendinosus anterior cruciate ligament reconstruction: the tibial tunnel stress-riser. Knee 2006;13:238–240. 53. Busfield BT, Safran MR, Cannon WD. Extensor mechanism disruption after contralateral middle third patellar tendon harvest for anterior cruciate ligament revision reconstruction. Arthroscopy 2005;21:1268. 54. Acton KJ, Dowd GS. Fracture of the tibial tubercle following anterior cruciate ligament reconstruction. Knee 2002;9:157–159. 55. Moen KY, Boynton MD, Raasch WG. Fracture of the proximal tibia after anterior cruciate ligament reconstruction: a case report. Am J Orthop 1998;27:629–630.

Anterior Knee Problems After Anterior Cruciate Ligament Reconstruction INTRODUCTION Anterior knee problems such as anterior knee pain, tenderness, crepitus, disturbed sensitivity, and inability to kneel or knee-walk after anterior cruciate ligament (ACL) reconstruction are common and, although they occur more often when patellar tendon autograft is used, they can be seen with other graft options as well. Anterior knee pain is multifactorial in origin and yet not clearly understood. The patellofemoral joint is a very vulnerable joint. It can be the source of pain after almost any surgery to the knee, even if it is not directly involved. The patellar tendon and peripatellar soft tissues are similarly vulnerable. Damage to the infrapatellar branch of the saphenous nerve with neuroma formation during graft harvesting, shortening of the patellar tendon after ACL reconstruction (patella baja) due to fibrosis of the infrapatellar fat pad, flexion and/or extension deficit due to poor surgical technique or inadequate rehabilitation, and pain stemming from tibial tunnel creation have all been implicated as possible causes. Pain during kneeling is bothersome, especially if interferes with certain recreational or occupational activities (e.g., masons, plumbers) and with religious (e.g., Islamic) or cultural habits (e.g., Asian peoples). In general, anterior knee problems can be due to factors related to the graft, the procedure,

or the rehabilitation. Of these, the most important factors are those related to the graft.

79 CHAPTER

Michael E. Hantes Apostolos P. Dimitroulias

ANTERIOR KNEE PROBLEMS RELATED TO THE GRAFT Patellar Tendon and Hamstring Tendon Autografts The impact of patellar tendon graft harvesting on knee symptoms is well documented. An increased incidence of anterior knee problems such as pain and loss of sensitivity was found in patients in whom a patellar tendon autograft was harvested from the “healthy” contralateral knee, and therefore this procedure should be avoided because additional problems and morbidity are transferred onto the healthy contralateral knee.1 The gold standard thus far for ACL reconstruction is the mid-third bone–patellar tendon–bone (BPTB) autograft. However, it has been associated with significant (in 40% to 60% of patients) anterior knee symptoms,2–7 and therefore the use of four-strand hamstring tendon graft is increasing in popularity because these problems seem to be less frequent. In the literature, results are conflicting in the comparison of the two most popular grafts (patellar and hamstring tendon) regarding the incidence of anterior knee pain.8–10

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Anterior Cruciate Ligament Reconstruction This variability in results is mostly due to inherent difficulties in achieving homogeneity in different studies owing to technical issues (method of graft harvest, preparation of the graft, cycling of the graft, degree of knee flexion and graft tension when securing the graft, fixation method, rehabilitation protocol, and outcome measures). The ideal way to compare the incidence of anterior knee symptoms between different types of grafts would be a large multicenter randomized trial, but such a large-scale trial has not yet been done. However, three meta-analyses concluded that ACL reconstructed knees with patellar tendon are more prone to developing anterior knee symptoms and extension deficit than the hamstring tendon group.11–13 In a study with a long-term follow-up,7 kneeling pain was found to persist even at 7 years postoperatively and was more common and more severe in the patellar tendon group (54%) than the hamstring tendon group (20%). Similarly, the incidence of donor site symptoms in any form was more than doubled in the patellar tendon group compared with the hamstring tendon group, and the incidence of extension deficit increased over time in the patellar tendon group, probably secondary to development of osteoarthritic changes.7

But what causes anterior knee problems after patellar tendon harvest? Harvesting trauma, patellar tendonitis, tendon changes during the repair process of the tendon gap, vascular damage of the retropatellar fat pad, and proprioceptive loss of the extension mechanism are all possible causes.14 Patellar tendon shortening is another important factor for development of anterior knee pain. It has been demonstrated with a magnetic resonance imaging (MRI) study15 that significant patellar tendon shortening (with a mean of 9.7%) occurs after harvesting BPTB graft compared with the contralateral nonoperated control knee 1 year after ACL reconstruction (Fig. 79-1). A possible explanation for this is the retropatellar fat pad fibrosis secondary to the surgical trauma, contraction of the scar that develops in the gap created after patellar tendon harvesting due to diminished elastic components, and the decreased strength of quadriceps contributing to patella baja, which stresses patellofemoral joint. Moreover, quadriceps inhibition/ weakness causes delayed rehabilitation with subsequent extension deficit and abnormal patellofemoral joint forces. In contrast, harvesting of hamstring tendons resulted in a nonsignificant shortening of the patellar tendon of 2.6%

FIG. 79-1 A, Measurement of the patellar tendon length in a sagittal magnetic resonance image (MRI) of a knee 16 months after anterior cruciate ligament (ACL) reconstruction with bone–patellar tendon–bone graft. B, Sagittal MRI of the contralateral healthy knee (3-mm difference, or 6.6%).

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Anterior Knee Problems After Anterior Cruciate Ligament Reconstruction (Fig. 79-2). Using an Insall-Salvati ratio less than 0.74 as the MRI criterion for patella baja diagnosis,16 12.5% of the patients in the BPTB group and 3% in the hamstring group were found to develop patella baja after surgery. This shortening was not of clinical importance, as it was not associated with anterior knee pain in the short-term follow-up. However, one other study with longer follow-up (average 7 years) has clearly shown that severity of patellofemoral joint arthritis and anterior knee symptoms correlate with the amount of patellar tendon shortening17 (Fig. 79-3). Central patellar tendon harvesting has been found to cause a slight medial displacement of the patella,18 and this alteration in position causes high contact forces in the medial patellofemoral joint.14 A solution to this may be the use of the medial third of the patellar tendon, which does not influence the patellofemoral angle and causes an insignificant lateral patellar displacement.18 Anterior knee pain does occur after hamstring ACL reconstruction, despite the fact that the anterior structures of the knee remain intact. The reason for this is not clear, but it is known that the patellofemoral joint can be the

79

source of pain after almost any surgery to the knee, even if the patellofemoral extension mechanism is not directly involved. The incidence of anterior knee pain after hamstring graft for ACL reconstruction in the literature is less than 23%.19–22 Evaluation of the pain with diagrams has shown that it is more diffuse and is not related to the skin incision for tendon harvesting or tibial tunnel drilling.19 In contrast, anterior knee pain after patellar tendon harvesting is more well localized, and palpation reveals trigger points that are usually over the inferior pole of the patella or the tibial tuberosity or above the patellar tendon donor site.14,23 There are conflicting reports in the literature on whether grafting the patella and tibial tunnel bone defects after BPTB harvesting reduces23,24 or does not reduce25 the incidence of anterior knee symptoms. There is also a report that patella grafting increases the incidence of painful spurs at the inferior pole of the patella.26 Similar arguments exist regarding whether suturing the patellar tendon gap facilitates tendon healing or is a cause of patellar tendon shortening.27 Patellar fracture is another important issue unique in BPTB grafts, and its incidence varies from 0.2%28 to 2.3%.29

FIG. 79-2 A, Measurement of the patellar tendon length in a sagittal magnetic resonance image (MRI) of a knee 14 months after anterior cruciate ligament (ACL) reconstruction with hamstring (HS) graft. B, Sagittal MRI of the contralateral healthy knee (1-mm difference, or 2.6%).

609

Anterior Cruciate Ligament Reconstruction

FIG. 79-3 A, Symptomatic patellofemoral arthritis in a young patient 4 years after anterior cruciate ligament (ACL) reconstruction with bone–patellar tendon–bone graft. B, Management with anteromedial tibial tubercle transfer (Fulkerson osteotomy).

Patellar tendon rupture is another rare complication that may occur after patellar tendon harvest. Devascularization and an alteration in tendon healing and remodeling are possible causes of this complication.30

of the saphenous nerve is not a problem because the incision does not cross them.

Central Quadriceps Tendon

During the past 30 years, allografts have been used commonly to reconstruct the ACL as an alternative to reduce donor site morbidity. Allograft choices consist of patellar tendon, quadriceps, hamstrings, Achilles, and anterior and posterior tibialis tendons and fascia lata. The most commonly used at present is BPTB allograft. The improved sterilization techniques with cryopreservation, which does not interfere with the mechanical properties of the graft, contributed to a rise of allograft use during recent years. Some studies comparing patellar tendon autograft versus allograft in ACL reconstruction failed to show any difference in the incidence of anterior knee pain between the two groups.33,34 Others found a significant reduction in anterior knee pain with allografts, such as 14% versus 46%35 and 14.4% versus 55.8%.36 In a study comparing patellar tendon autograft versus allograft with long-term follow-up (5 years), it was found

Use of quadriceps tendon autograft has been introduced to overcome disadvantages of patellar tendon and hamstring grafts. Literature is limited on the use of this graft, but initial experience has been promising with regard to anterior knee problems. In a recent study, less than 10% of patients with quadriceps tendon graft suffered anterior knee pain in various activities, and only 6% complained of kneeling pain.31 Donor site irritation over the proximal patellar border was observed in several patients but did not last more than 6 months, and quadriceps strength 1 year postoperatively was comparable with that of other autografts in the literature.31 The risk of patellar fracture must be lower than that of patellar tendon graft because the bone in the proximal patellar pole is more dense.32 Injury of infrapatellar branches 610

Allografts

Anterior Knee Problems After Anterior Cruciate Ligament Reconstruction

79

that the autograft group experienced more pain during the first 3 postoperative months, which relates to the larger incision required and the resulting bony defect.37 At 2 and 5 years there was no difference in the pain. Moreover, both in the short and long terms, there was no difference in the range of motion and quadriceps strength. However, incision site complaints (tenderness, irritation, numbness) are less common in the allograft group when compared with the autologous BPTB group.33

ANTERIOR KNEE PROBLEMS RELATED TO THE PROCEDURE The infrapatellar branch of the saphenous nerve has two main trunks, superior and inferior,38 coursing laterally and slightly distally, respectively (Fig. 79-4). Incisions close to the tibial tubercle and over the patellar tendon may damage these branches with consequent anesthesia, dysesthesia, or painful neuroma formation.39 A significant correlation exists between disturbed anterior knee sensitivity and subjective anterior knee pain as well as discomfort during knee walking.40,41 Moreover, there is an association between injury of these sensory branches and development of reflex sympathetic dystrophy.37 The importance of infrapatellar branches can be appreciated by reports of prepatellar neuralgia after direct blows to the anterior knee.42,43 Patients should be informed of these potential complications. The area of anesthesia is variable but always lateral to the incision. It is not only the incision for graft harvesting that puts in danger these sensory branches; the incision for the medial portal can damage them as well.38,39 Therefore some propose a horizontal rather than vertical incision for the portals to minimize the risk of nerve damage.38 Another maneuver to avoid damage of these nerves is placing the anterior midline skin incision with the knee held in 90 degrees of flexion. In this way the inferior branch moves farther distally and the risk of inadvertent damage is lessened.38 When harvesting patellar tendon autograft with a small midline incision, every effort should be made to identify and protect these sensory nerve branches. Alternative techniques have been described for subcutaneous patellar tendon harvesting using two horizontal incisions,44 one horizontal incision at the midlevel of the patellar tendon,23 and two vertical41 incisions. This way the infrapatellar branches are avoided, making these incisions less likely to become a source of pain. Injury to these branches can occur not only during patellar tendon harvesting but with hamstring tendon as well. Anterior knee sensory changes were found to be as high as 50% (at a minimum of 24 months postoperatively) following hamstring ACL reconstruction.19 The inadvertent injury of the sensory nerve branches may occur during the

FIG. 79-4 The infrapatellar branch of the saphenous nerve with the two main trunks, superior and inferior, coursing laterally and distally. (Reprinted with permission from Kartus J, Ejerhed L, Sernert N, et al. Comparison of traditional and subcutaneous patellar tendon harvest. A prospective study of donor site-related problems after anterior cruciate ligament reconstruction using different graft harvesting techniques. Am J Sports Med 2000;28:328–335.)

skin incision, the dissection for the tendons, tendon stripping (as the saphenous nerve courses superficial to gracilis), and tibial tunnel drilling.19 However, it seems that the more distal the location of the area of disturbed sensitivity (as occurs after hamstring tendon harvesting), the less discomfort will result.45 In contrast with patellar tendon harvesting, the area of sensory changes is more proximal and thus more bothersome. Concomitant meniscal surgery during ACL reconstruction may result in range of motion problems during rehabilitation, which will influence the incidence of anterior knee problems. Residual anterior instability after surgery can cause anterior knee problems secondary to the altered patellofemoral kinematics (lateral patellar tilt and shift) present in ACL deficient knees. 611

Anterior Cruciate Ligament Reconstruction Proper placement of the drill holes at the isometric point is a prerequisite to achieve full range of motion postoperatively.40 It has been found in a study that after BPTB ACL reconstruction, patients with patellofemoral joint arthritis tended to have more anterior placement of the femoral tunnel and more posterior placement of the tibial tunnel than those without patellofemoral joint arthritis.17 Arthrofibrosis after ACL reconstruction may result from an exaggerated inflammatory response, synovitis, or a sympathetic algodystrophy and will cause range-of-motion deficit.10 Formation of a “Cyclops” lesion is another reason for extension deficit and anterior knee pain.46 This lesion is usually formed anterolaterally to the tibial tunnel placement of the graft. Arthroscopic débridement of the nodule can improve extension.

ANTERIOR KNEE PROBLEMS RELATED TO REHABILITATION An operation performed too early (i.e., before regaining full range of motion) is a well-known cause of postoperative range of motion deficit. For this reason we support a rather delayed reconstruction, not less than 2 months after the injury, to allow for posttraumatic synovitis to settle or the knee to regain full range of motion without effusion.47,48 Reduced strength and loss of range of motion are correlated with anterior knee pain after ACL reconstruction using all kinds of grafts.49 Thereby every effort should be made postoperatively to achieve full range of motion and regain quadriceps and hamstrings muscle strength. Loss of hyperextension can be a significant cause of anterior knee discomfort after ACL reconstruction.50–53 The reason for

All grafts

Arthrofibrosis Cyclops lesion Inappropriate drill holes Delayed rehabilitation

anterior knee symptoms in loss of extension is the resultant increase of patellofemoral joint reaction forces. It is not only loss of extension that can cause anterior knee symptoms but loss of flexion as well, although this has been more controversial.52,54 Patients with both flexion and extension deficits have more anterior knee pain than patients with an extension deficit alone.40 The reason for anterior knee symptoms in loss of flexion is the decreased muscle strength in both flexor and extensor mechanisms40 (Fig. 79-5).

HOW TO REDUCE ANTERIOR KNEE SYMPTOMS AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Although the results in terms of restored laxity and a return to sports have been good after ACL reconstruction, anterior knee symptoms can be a problem after this procedure. Therefore efforts should be made to minimize the presence of anterior knee symptoms after ACL reconstruction in order to increase patient satisfaction. The donor site morbidity associated with harvesting a hamstring tendon graft is less common than that associated with harvesting a BPTB autograft. Therefore fewer problems should be expected when harvesting a hamstring tendon graft. Probably this type of graft is a better choice than patellar tendon graft for patients whose activities require kneeling. Quadriceps tendon autograft seems to be an alternative choice for ACL reconstruction, although further studies are needed to support this hypothesis. When patellar tendon is used, the technique involving two transverse incisions significantly reduces anterior knee symptoms. A horizontal incision may be a useful option for hamstring graft harvesting to provide a more satisfactory scar

Extension deficit

Abnormal PFJ forces

BPTB

BPTB and HS

Poor quads strength Retropatellar fat fibrosis PT scar contraction Medial displacement of patella

PT shortening

Injury to the infrapatellar branches of saphenous nerve

Anesthesia, dysesthesia or painful neuroma

Anterior knee pain

FIG. 79-5 Causes of anterior knee pain after anterior cruciate ligament (ACL) reconstruction. BPTB, Bone–patellar tendon–bone; HS, hamstring; PFJ, patellotemoral joint.

612

Anterior Knee Problems After Anterior Cruciate Ligament Reconstruction with less risk of damage to the infrapatellar branch of the saphenous nerve. However, regardless of the incision used, damage to the infrapatellar branch of the saphenous nerve is a potential complication (for patellar tendon and hamstring autografts), and patients should be counseled about this preoperatively. Postoperative rehabilitation with control of pain, soft tissue swelling, and hemarthrosis and the institution of immediate motion, patellar mobilization, and quadriceps exercises are of paramount importance in the prevention of knee motion complication and anterior knee problems. In addition, all patients should be instructed to achieve early knee extension. Finally, surgical technique is probably the most important factor to prevent anterior knee symptoms. Meticulous technique during soft tissue dissection and graft harvesting, accurate placement of the graft, and stable graft fixation to allow early rehabilitation are essential factors for a good result.

13.

14.

15.

16. 17.

18.

19.

References 20. 1. Mastrokalos DS, Springer J, Siebold R, et al. Donor site morbidity and return to the preinjury activity level after anterior cruciate ligament reconstruction using ipsilateral and contralateral patellar tendon autograft: a retrospective, nonrandomized study. Am J Sports Med 2005;33:85–93. 2. Corry I, Webb M, Clingeleffer A, et al. Arthroscopic reconstruction of the anterior cruciate ligament. Am J Sports Med 1999;27:444–454. 3. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2001;83B:348–354. 4. Shaieb M, Kan D, Chang S, Marumoto J, et al. Prospective randomised comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:214–220. 5. Feller JA, Webster KE. A randomised comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 6. Forster MC, Forster IW. Patellar tendon or four-strand hamstring? A systematic review of autografts for anterior cruciate ligament reconstruction. Knee 2005;12:225–230. 7. Roe J, Pinczewski LA, Russell VJ, et al. A 7-year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction differences and similarities. Am J Sports Med 2005;33:1337–1345. 8. Spindler KP, Kuhn JE, Freedman KB, et al. Anterior cruciate ligament reconstruction autograft choice: bone-tendon-bone versus hamstring. Does it really matter? A systematic review. Am J Sports Med 2004;32:1986–1995. 9. Herrington L, Wrapson C, Matthews M, et al. Anterior cruciate ligament reconstruction, hamstring versus bone-patella tendon-bone grafts: a systematic literature review of outcome from surgery. Knee 2005;12:41–50. 10. Biau DJ, Tournoux C, Katsahian S, et al. Bone-patellar tendon-bone autografts versus hamstring autografts for reconstruction of anterior cruciate ligament: meta-analysis. Br J Med 2006;332:995–1001. 11. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction: a metaanalysis. Arthroscopy 2001;17:248–257. 12. Freedman KB, D’Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

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tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. Thompson J, Harris M, Grana WA. Patellofemoral pain and functional outcome after anterior cruciate ligament reconstruction: an analysis of the literature. Am J Orthop 2005;34:396–399. Breitfuss H, Frohlich R, Povacz P, et al. The tendon defect after anterior cruciate ligament reconstruction using the midthird patellar tendon: a problem for the patellofemoral joint? Knee Surg Sports Traumatol Arthrosc 1996;3:194–198. Hantes M, Zachos V, Bargiotas K, et al. Patellar tendon length after anterior cruciate ligament reconstruction. A comparative magnetic resonance imaging study between patellar and hamstring tendon autografts. Knee Surg Sports Traumatol Arthrosc 2007;15:712–719. Shabshin N, Schweitzer ME, Morrison WB, et al. MRI criteria for patella alta and baja. Skeletal Radiol 2004;33:445–450. Jarvela T, Paakkala T, Kannus P, et al. The incidence of patellofemoral osteoarthritis and associated findings 7 years after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18–24. Moebius U, Georgoulis AD, Papageorgiou CD, et al. Alterations of the extensor apparatus after anterior cruciate ligament reconstruction using the medial third of the patellar tendon. Arthroscopy 2001;17:953–959. Spicer DD, Blagg SE, Unwin AJ, et al. Anterior knee symptoms after four-strand hamstring tendon anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2000;8:286–289. Sgaglione NA, Del Pizzo W, Fox JM, et al. Arthroscopically assisted anterior cruciate ligament reconstruction with the pes anserine tendons. Comparison of results in acute and chronic ligament deficiency. Am J Sports Med 1993;21:249–256. Otero AL, Hutcheson LA. A comparison of the doubled semitendinosus/gracilis and central third of the patellar tendon autografts in arthroscopic anterior cruciate ligament reconstruction. Arthroscopy 1993;9:143–148. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. Tsuda E, Okamura Y, Ishibashi Y, et al. Techniques for reducing anterior knee symptoms after anterior cruciate ligament reconstruction using a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:450–456. Muellner T, Kaltenbrunner W, Nikolic A, et al. Shortening of the patellar tendon after anterior cruciate ligament reconstruction. Arthroscopy 1998;14:592–596. Boszotta H, Prunner K. Refilling of removal defects: impact on extensor mechanism complaints after use of a bone-tendon-bone graft for anterior cruciate ligament reconstruction. Arthroscopy 2000;16:160–164. Kohn D, Sander-Beuermann A. Donor-site morbidity after harvest of a bone-tendon-bone patellar tendon autograft. Knee Surg Sports Traumatol Arthrosc 1994;2:219–223. Brandsson S, Faxen E, Eriksson BI, et al. Closing patellar tendon defects after anterior cruciate ligament reconstruction: absence of any benefit. Knee Surg Sports Traumatol Arthrosc 1998;6:82–87. Viola R, Vianello R. Three cases of patella fracture in 1,320 anterior cruciate ligament reconstructions with bone-patellar tendon-bone autograft. Arthroscopy 1999;15:93–97. Brown CH. ACL Surgery. Graft options: patellar tendon, hamstrings tendons, quadriceps tendon, and allografts. In Sim FH (ed): American Academy of Orthopaedic Surgeons 2001 instructional course lectures. Park Ridge, IL, 2001, American Academy of Orthopaedic Surgeons, pp 447–458. Marumoto JM, Mitsunaga MM, Richardson AB, et al. Late patellar tendon ruptures after removal of the central third for anterior cruciate ligament reconstruction: a report of two cases. Am J Sports Med 1996;24:698–701.

613

Anterior Cruciate Ligament Reconstruction 31. Lee S, Seong SC, Jo H, et al. Outcome of anterior cruciate ligament reconstruction using quadriceps tendon autograft. Arthroscopy 2004;20:795–802. 32. West RV, Harner CD. Graft selection in anterior cruciate ligament reconstruction. J Am Acad Orthop Surg 2005;13:197–207. 33. Peterson RK, Shelton WR, Bomboy AL. Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy 2001;17:9–13. 34. Shelton WR, Papendick L, Dukes AD. Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy 1997;13:446–449. 35. Bach BR Jr, Aadalen KJ, Dennis MG, et al. Primary anterior cruciate ligament reconstruction using fresh-frozen, nonirradiated patellar tendon allograft: minimum 2-year follow-up. Am J Sports Med 2005;33:284–292. 36. Gorschewsky O, Klakow A, Riechert K, et al. Clinical comparison of the Tutoplast allograft and autologous patellar tendon (bone-patellar tendon-bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. Am J Sports Med 2005;33:1202–1209. 37. Poehling GG, Pollock FE Jr, Koman LA. Reflex sympathetic dystrophy of the knee after sensory nerve injury. Arthroscopy 1988;4:31–35. 38. Tifford CD, Spero L, Luke T, et al. The relationship of the infrapatellar branches of the saphenous nerve to arthroscopy portals and incisions for anterior cruciate ligament surgery. An anatomic study. Am J Sports Med 2000;28:562–567. 39. Mochida H, Kikuchi S. Injury to infrapatellar branch of saphenous nerve in arthroscopic knee surgery. Clin Orthop 1995;320:88–94. 40. Kartus J, Magnusson L, Stener S, et al. Complications following arthroscopic anterior cruciate ligament reconstruction. A 2–5-year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc 1999;7:2–8. 41. Kartus J, Ejerhed L, Sernert N, et al. Comparison of traditional and subcutaneous patellar tendon harvest. A prospective study of donor siterelated problems after anterior cruciate ligament reconstruction using different graft harvesting techniques. Am J Sports Med 2000;28:328–335.

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42. Detenbeck LC. Infrapatellar traumatic neuroma resulting from dashboard injury. J Bone Joint Surg 1972;54A:170–172. 43. Gordon GC. Traumatic prepatellar neuralgia. J Bone Joint Surg 1952;34B:41–44. 44. Mishra AK, Fanton GS, Dillingham MF, et al. Patellar tendon graft harvesting using horizontal incisions for anterior cruciate ligament reconstruction. Arthroscopy 1995;11:749–752. 45. Eriksson K. On the semitendinosus in anterior cruciate ligament reconstructive surgery. Stockholm, Sweden, 2001, Karolinska Institutet [thesis.]. 46. Jackson DW, Schaefer PK. Cyclops syndrome: loss of extension following intra-articular anterior cruciate ligament reconstruction. Arthroscopy 1990;6:171–178. 47. Shelbourne KD, Wilckens JH. Current concepts in anterior cruciate ligament rehabilitation. Orthop Rev 1990;19:957–964. 48. Aglietti P, Buzzi R, D’Andria S, et al. Patellofemoral problems after intraarticular anterior cruciate ligament reconstruction. Clin Orthop 1993;288:195–204. 49. Kartus J, Movin T, Karlsson J. Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts. Arthroscopy 2001;17:971–980. 50. Harner CD, Irrgang JJ, Paul J, et al. Loss of motion after anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:499–506. 51. Irrgang JJ, Harner CD. Loss of motion following knee ligament reconstruction. Sports Med 1995;19:150–159. 52. Sachs RA, Daniel DN, Stone ML, et al. Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760–765. 53. Shelbourne KD, Trumper R. Preventing anterior knee pain after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:41–47. 54. Stapleton TR. Complications in anterior cruciate ligament reconstructions with patellar tendon grafts. Sports Med Arthrosc Rev 1997;5:156–162.

PART R GAIT ANALYSIS AND TISSUE ENGINEERING

Gait Analysis in Anterior Cruciate Ligament Deficient and Reconstructed Knees INTRODUCTION Anterior cruciate ligament (ACL) rupture is a common injury of the knee joint that usually results in surgical reconstruction.1,2 The goal of ACL reconstruction and subsequent rehabilitation is to restore the knee to an acceptable muscular strength and joint stability.3,4 The stability of the knee thought to have an ACL injury is traditionally evaluated with an arthrometer (i.e., KT-1000) while the patient is in a standard static position. The arthrometer provides the clinician with a quantitative measure of the amount of passive movement between the femur and the tibia. A minimal amount of joint laxity during the test is considered to be clinically and functionally acceptable. However, such an evaluation is a measure of passive joint stability and does not provide a measure of the joint’s stability during daily physical activities.5–7 Dynamic functional joint stability is defined as the condition in which the joint is stable during daily physical activities.5 Previous research has indicated that there is lack of a relationship between passive and dynamic functional joint stability.5,8–10 Recently, gait analysis has been used to quantify the dynamic functional knee stability after ACL reconstruction.11–14 Gait analysis can be defined as an advanced laboratory process by which present day electronics (i.e., video * Dr. Stergiou is supported by the National Institutes of Health (K25HD047194), the National Institute on Disability and Rehabilitation Research (H133G040118), and the Nebraska Research Initiative.

cameras) are used to integrate information from a variety of inputs in order to demonstrate and analyze the dynamics of gait (Fig. 80-1). For example, gait analysis can offer a more indepth evaluation of movement patterns by providing information on each joint. Such information has also become common practice in many other orthopaedic areas where the effects of surgical procedures (i.e., joint arthroplasty, cerebral palsy) are evaluated to identify gains in mobility.15–19 The use of this technology allows the development of normal joint movement profiles that can be used to identify abnormalities, helping in this way to improve diagnosis, treatment, design, and performance of reconstructive surgery and rehabilitation programs. Gait analysis, using advanced computerized systems in conjunction with multiple high-speed (i.e., 200 frames per second) video cameras, can document three-dimensional (3D) knee joint movement profiles.20 Thus all six degrees of freedom of the knee joint can now be discerned, and the dynamic functional levels of individuals performing everyday activities can be objectively measured and evaluated. This is accomplished by obtaining data from surface markers that are placed on specific anatomical bony landmarks. The position of the markers in space is recorded, and then joint movement profiles can be acquired. A possible limitation of gait analysis is that surface markers may not accurately represent the underlying bone motion during highly dynamic activities,21 as the markers are attached on the skin and not directly on the bone. As skin movement

80 CHAPTER

Nicholas Stergiou* Stavros Ristanis Constantina Moraiti Anastasios Georgoulis

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Jumping

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3 FIG. 80-1 A stick figure demonstrating the landing activity: the subject jumps off the platform and lands with both feet on the ground. Following foot contact, the subject pivots (externally rotates) on the right or left (ipsilateral) leg at 90 degrees and walks away from the platform. While pivoting, the contralateral leg is swinging around the body and the trunk is oriented perpendicularly to the platform.

increases, the location of the marker and of the underlying bone differs. As a result, error is introduced.21–26 One way to avoid these limitations is to directly measure skeletal motion with intracortical pins.25 However, the applicability of this method is limited because the implantation of intracortical pins is a 616

highly invasive procedure that may cause discomfort or pain to the patient and result in restriction of movements. In addition, implantation of intracortical pins is a method that is limited by the sample size, as an effective number of volunteers cannot be found.

Gait Analysis in Anterior Cruciate Ligament Deficient and Reconstructed Knees These limitations can also be addressed with careful experimentation procedures. The following are a few of the procedures commonly used: 1 Minimize interoperator error by having the same clinician place all markers and acquire all anthropometric measurements. 2 Incorporate a standing calibration procedure to correct for subtle misalignment of the markers that define the local coordinate system and to provide a definition of zero degrees for all movements in all planes. 3 Maximize your control conditions to “tease” out true differences. For example, in our research work,14,27 we used as control conditions both the intact leg of the ACL reconstructed or deficient group and a completely healthy group of individuals. 4 Always use the same instrumentation for all individuals to maintain the same level of measurement noise across all individuals. Thus any differences can be attributed to changes within the system itself. 5 Increase statistical power by using an adequate sample size and selecting the proper alpha level. These suggestions can solidify conclusions drawn from gait analysis. Thus gait analysis is widely accepted at the present time and is considered a well-established and reliable method.28,29 This methodology allows the in vivo evaluation of the ACL deficient and reconstructed knee during dynamic activities (i.e., walking, pivoting), something that static measures (i.e., arthrometer) are unable to do.

IMPORTANCE OF IN VIVO BIOMECHANICAL RESEARCH TO QUANTIFY SUCCESS OF SURGICAL TECHNIQUES Example 1: Tibial Rotation In this section, we will present our first example of how gait analysis and in vivo biomechanics can help quantify success in the operating room. For this example, we will focus on knee joint rotational movement patterns for which in vivo research work is scanty. Our investigations have examined knee joint rotational movement patterns during high- and low-demand activities in both ACL deficient and reconstructed individuals. In our first study, we evaluated ACL deficient and reconstructed individuals during a low-demand activity such as walking.14 We examined 13 individuals with unilateral ACL deficiency, 21 individuals who had undergone ACL reconstruction, and 10 healthy controls. ACL reconstruction was done

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arthroscopically using a bone–patellar tendon–bone (BPTB) autograft. We found that the ACL deficient group exhibited significantly increased tibial rotation range of motion during the initial swing phase of the gait cycle when compared with the ACL reconstructed and control groups. Thus our results demonstrated that ACL deficiency produced rotational differences at the knee during walking. These differences did not exist when we compared the ACL reconstructed group with the control. Thus, in this low-demand activity, the surgical reconstruction restored tibial rotation to normal levels. Next, we wanted to identify whether this is also the case in a higher-demand activity that can apply increased rotational loading at the knee. Therefore we examined 18 ACL reconstructed individuals and 15 controls during a highdemand activity (descending stairs and subsequent pivoting).27 The ACL reconstruction was done arthroscopically, again using a BPTB autograft. The evaluation was performed at an average of 12 months after reconstruction. The individuals were asked to descend three steps and then immediately pivot on the landing leg at 90 degrees and walk away from the stairway while kinematic data were collected. The tibial rotation range of motion during the pivoting period was found to be significantly larger in the ACL reconstructed leg compared with the contralateral intact leg and the healthy control. No significant differences were found between the healthy control leg and the intact leg of the ACL reconstructed group. Therefore our results demonstrated that tibial rotation remained abnormal and significantly increased 1 year after ACL reconstruction during high-demand activities such as pivoting after descending from stairs. To verify our findings, we performed an additional experiment in which we evaluated another high-demand activity.30 Data were collected while the subjects jumped off a 40-cm platform and landed on the ground; following foot contact, they immediately pivoted at 90 degrees and walked away from the platform. We chose this activity because landing from a jump is a task that places higher demands on the knee than walking or even stepping down.31,32 We combined landing with a subsequent pivoting to create rotational loads on the knee. The subjects were 11 patients, all ACL reconstructed with the same arthroscopic technique using a BPTB autograft, 1 year after the surgery; 11 ACL deficient subjects who had sustained the injury more than 1 year prior to testing; and 11 controls. The same dependent variable was evaluated as in the previous study.27 Both the reconstructed leg of the ACL group and the deficient leg of the ACL deficient group had significantly larger tibial rotation values than in the healthy control group. We also found no significant differences between the deficient leg of the ACL deficient group and the reconstructed leg of the ACL reconstructed group. It was 617

Anterior Cruciate Ligament Reconstruction concluded that current ACL reconstruction using the BPTB autograft is inadequate to restore excessive tibial rotation during an activity such as landing and subsequent pivoting, which practically simulates sport activities. Next, we wanted to identify whether tibial rotation remains excessive for a longer period: 2 years following the reconstruction. We speculated that it is possible adaptations will set in and the patients will compensate. Thus we performed a follow-up evaluation33 in nine ACL reconstructed subjects who had participated in our previous study.30 We examined them with the same methodology and for both activities that we used in our previous work.27,30We also incorporated a control group of 10 individuals. We found that tibial rotation remained significantly excessive even 2 years after the reconstruction. This result was verified with comparisons conducted with both the intact contralateral knees of our patient group and with the healthy controls. Furthermore, we found that tibial rotation of the intact knee of our patient group was similar to those recorded from the healthy control group. In all of our previous work, ACL reconstruction was performed with a BPTB autograft. Thus it was logical to question whether tibial rotation will remain excessive if an alternative autograft is used. Such an autograft is the quadrupled hamstring tendon (semitendinous and gracilis [ST/Gr]). Originally we hypothesized that the ST/Gr autograft would be able to restore tibial rotation during our experimental protocols due to its superiority in strength and linear stiffness34–37 and because it is closer morphologically to the anatomy of the natural ACL.34–36 We examined 11 individuals who were ACL reconstructed with an ST/Gr autograft, 11 individuals who were ACL reconstructed with a BPTB autograft, and 11 healthy controls.38,39 The experimental protocol was identical to our previous studies. Tibial rotation was found to be significantly larger in both ACL reconstructed groups when compared with the healthy controls. Therefore our hypothesis was refuted, and we concluded that ACL reconstruction using the ST/Gr autograft is as inadequate as the one using the BPTB autograft in terms of restoring excessive tibial rotation. The results of our studies were also supported by in vitro research work in which the biomechanical efficiency of the ACL reconstruction has also been questioned.40–43 These studies showed that ACL reconstruction was successful in limiting anterior tibial translation in response to an anterior tibial load but was insufficient to control a combined rotatory load of internal and valgus torque. Furthermore, our tibial rotational values were in close agreement with the in vitro work.40 In summary, our research work showed how gait analysis and in vivo biomechanics can help quantify success in the operating room. We found that ACL deficiency results in abnormal movement patterns such as excessive tibial rotation. 618

ACL reconstruction seems to restore ACL function regarding tibial rotation in low-demand activities such as walking. However, this is not the case in higher-loading activities such as during pivoting, immediately following step-down, or in a landing from a jump. These types of activities can reveal differences that are masked during low-demand activities.

Example 2: Dynamic Functional Knee Stability Using Nonlinear Analysis In this section we present our second example of how gait analysis and in vivo biomechanics can help measure dynamic functional knee stability. For this example, we will focus on our research work in which we used nonlinear tools to examine whether an injured joint is functionally stable during daily physical activities. Biomechanists have recently proposed that the use of stride-to-stride variability, defined as fluctuations on the walking movement patterns from one stride to the next, provides a quantitative measure of functional joint stability.44–47 This proposal is based on scientific evidence that neuromuscular pathology is related to an increased amount of stride-to-stride variability.44–47 Hence a “biomechanical” hypothesis has been formed in which neuromuscular pathology is related to an increased amount of variability and deterioration of functional stability. However, this biomechanical hypothesis lacks support in other medical domains. Numerous studies in diverse medical areas have shown that a decreased amount of variability is related to pathology. These investigations include medical domains such as heart rate irregularities, sudden cardiac death syndrome, blood pressure control, brain ischemia, and epileptic seizures.48–55 Hence a contradictory hypothesis has been proposed in which variability is described as “healthy flexibility.”56–58 These investigations indicate that variations in the behavior of the biological system may be necessary to provide flexible adaptations to everyday stresses placed on the human body. Alternatively, a lack of healthy flexibility is associated with rigidity and inability to adapt to stresses. Based on this logic, it is possible that injury or pathology can result in a loss of healthy flexibility that may not be regained despite surgical treatment (loss of complexity hypothesis). This contradiction in the literature may be due to the usage of linear tools (i.e., standard deviation) to assess stride-to-stride variability.44–47 Linear tools only provide a measure of the amount of variability that is present in the gait pattern and may mask the true structure of motor variability. Masking occurs when strides are averaged to generate a “mean” picture of the subject’s gait. This averaging procedure may lose the temporal variations of the gait pattern. Additionally, the statistical processing of linear measures requires random and independent variations between subsequent strides.

Gait Analysis in Anterior Cruciate Ligament Deficient and Reconstructed Knees

Flexion-Extension

A 65 55 45 35 25 15 5 −5

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Recent studies have overcome the problems of linear measures by using nonlinear tools such as the Approximate Entropy.59–62 These studies have determined that variations in the gait pattern are distinguishable from noise and have a deterministic origin. A deterministic origin indicates that stride-to-stride variations are neither random nor independent. Rather, these variations have a meaningful pattern that characterizes the behavior of the locomotive system. Linear tools are not able to provide such information. Thus the ability to quantify the characteristic features of these variations has been the strength of using nonlinear tools to support the “loss of complexity” hypothesis. In our research work, we wanted to quantify knee joint stride-to-stride variability in ACL deficient and reconstructed individuals during a common daily activity such as walking. We used nonlinear analysis to explore whether the “loss of complexity” hypothesis can also be generalized to orthopaedic-related problems. In our first study62 we examined ten subjects with unilateral ACL deficiency who walked on a treadmill at different speeds while kinematic data were collected for 80 consecutive strides for each speed. The Approximate Entropy of the resultant knee joint flexion–extension kinematic data was calculated (Fig. 80-2). The ACL deficient knee had significantly smaller values than the intact contralateral knee. This indicated more regular and repeatable movement patterns for the injured knee and a decrease in healthy flexibility, as mentioned previously. Therefore nonlinear measures such as Approximate Entropy could prove to be of great importance in orthopaedics, providing the clinician with a mean of dynamical assessment of the effect of the pathology on movement and of the results of various therapeutic interventions. In addition, we believe that the “loss of complexity” hypothesis may be more universal than its proponents suggested. Pathologies of biorhythms are similar no matter whether one deals with the cardiovascular, nervous, or musculoskeletal system. FIG. 80-2 Approximate Entropy (ApEn) is a nonlinear measure that quantifies the regularity (predictability) of a time series. The smaller the ApEn, the more regular and predictable the system. ApEn values range from 0 to 2. A value of 0 corresponds to a periodic behavior, whereas a value of 2 describes a completely random time series. The examples of these five time series illustrate this issue. A, The time series from a simple periodic function sin(t/10). Periodic behavior always repeats itself and is highly predictable. The ApEn value of this time series is 0. B, Representative knee flexion–extension time series from an anterior cruciate ligament (ACL) deficient knee. The ApEn value of this time series is 0.2236. C, Representative knee flexion–extension time series of the contralateral intact knee. The ApEn value of this time series is 0.2646. It is evident that the subtle differences detected with the use of ApEn between these two latter time series cannot be discerned with the naked eye. D, A time series from a known chaotic system (the Lorenz attractor). The ApEn value of this time series is 0.3552. E, A time series from random numbers with a Gaussian noise centered on 0 and a standard deviation of 1.0. The ApEn value of this time series is 2.

619

Anterior Cruciate Ligament Reconstruction Next, we wanted to examine the effect of an ACL reconstruction on knee joint stride-to-stride variability.63 Again, we used the same nonlinear analysis, the Approximate Entropy. We examined six individuals who were ACL reconstructed with an ST/Gr autograft, seven individuals who were ACL reconstructed with a BPTB autograft, and 12 healthy controls. All subjects walked on a treadmill at a self-selected pace while kinematic data were collected from 120 consecutive strides. The control group had the smallest Approximate Entropy values, whereas the ST/Gr group had the largest. Significant differences were found only between the control and the ST/Gr reconstructed knees. We concluded that the ST/Gr reconstructed knee flexion/extension movement patterns during walking are less regular and repeatable than in the healthy control knee. However, the BPTB reconstructed knee seems to exhibit properties similar to the control. In addition, the results are also quite intriguing because they showed that the ACL reconstruction led to increased “flexibility” in the system. In the next section, we will present a theoretical explanation for this research outcome. In summary, our research work demonstrated how knee stride-to-stride variability, which can be measured with gait analysis and analyzed with nonlinear measures, can help quantify functional knee stability during activities of daily living. We found that ACL deficiency results in a “loss of complexity,” which is in agreement with the general medical literature that pathology will decrease variability. However, we found that ACL reconstruction increased variability, and thus complexity, as compared with healthy controls.

ADVANCED THEORETICAL CONSIDERATIONS Development of Osteoarthritis Due to Excessive Tibial Rotation Degeneration of the knee joint and eventual development of osteoarthritis have been associated with ACL deficiency. Longitudinal follow-up studies have shown that ACL deficiency leads to the development of chondral injuries, meniscal tears, degeneration of the articular cartilage, and eventually posttraumatic arthritis.64–68 However, similar problems have also been found longitudinally in the ACL reconstructed knee.69 Even more disturbingly, such findings have been seen shortly after the reconstruction as well.70 Therefore ACL reconstruction cannot protect the knee from progressing to degenerative change. Based on our research results presented earlier, we would like to propose that excessive tibial rotation may be an abnormal movement mechanism that degenerates soft tissues (i.e., cartilage), resulting in osteoarthritis. We hypothesize that because current ACL reconstruction procedures 620

cannot exactly replicate normal ACL anatomical complexity, they cannot restore normal tibiofemoral kinematics at the knee joint, thus leading to pathological movement patterns. These patterns also exist in ACL deficient knees. The abnormal rotational movements of the articulating bones at the knee could result in the applications of loads at areas of the cartilage that are not commonly loaded in a healthy knee. It has been shown that normal functional loading results in increased resistance of the cartilage by improving the mechanical stiffness and the proteoglycan content of the tissue.71–74 Furthermore, in joints that are prone to arthrosis, it has been found that the best-preserved cartilage areas are those of higher loading.75 Therefore in a healthy knee there are areas that are commonly loaded and others that are not. These latter areas, due to lack of sufficient cartilage, may not be able to withstand the newly introduced loading that is the result of the abnormal rotational movements of the articulating bones. Over time this could lead to knee osteoarthritis.

A Modified Complexity Hypothesis Model Changes in the system’s variability have been associated with pathology in several medical areas. Using few examples from cardiology, Kleiger et al (1987)76 showed a correlation between decreased heart rate variability (greater rigidity) and increased mortality in subjects who had suffered an acute myocardial infarction. Kaplan et al (1991)77 showed decreases in cardiovascular variability with age and concluded that variability as measured with nonlinear tools may be a useful physiological marker. Similarly, decreases in variability have been reported in electroencephalographic (EEG) tracings during seizures when compared with resting EEG recordings.78 Our research work explored another physiological biorhythm, stride-to-stride variability, which can be mapped to heart rate variability. We showed that musculoskeletal pathology (i.e., ACL rupture) can also lead to similar results as in other medical areas where the “loss of complexity” hypothesis has been proposed. Our previously discussed results supported the “loss of complexity” hypothesis in the ACL deficient knee. However, they also provide ground for an even more interesting hypothesis regarding musculoskeletal variability. It is possible that changes in knee stride-to-stride variability may in fact be the consequence of modifications, not only in the deterministic operation of the adaptive complex control systems, but also in intrinsic stochasticity (noise). It is possible that musculoskeletal variability can actually be represented by a continuum. The two ends of the continuum are complete periodicity and complete randomness (see also Fig. 80-2). A “healthy” optimal variability or “complexity” by a motor system is somewhere between the two ends. Decreases or losses can make the system more rigid/periodic and less adaptable, as in the

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ACL deficient knee. Thus an individual with ACL deficiency is more cautious in the way that he or she walks, trying to eliminate any extra movements, and thus is more rigid. On the other hand, increases can make the system more noisy, as in the ACL reconstructed knee with the ST/Gr autograft. Thus an individual, knowing that now the ACL is reconstructed, feels secure in increasing and adding extra movements. However, because the proper proprioceptive channels are not exactly present, more noise enters in the system, resulting in excess movements. These deviations from the healthy optimal variability may result in a knee more susceptible to acute and chronic injury. If the knee is more rigid as in ACL deficiency or noisier as in ACL reconstruction, it may reduce the capability of the joint to respond to different perturbations and adapt to the changing environment. This may in turn increase susceptibility to injury and future pathology, such as the development of degenerative knee arthritis. One of our future goals is to further test this model and verify the just-presented hypothesis. We also believe that the examination of the knee stride-to-stride variability will become a routine examination among orthopaedists to examine dynamic functional knee stability.

RECOMMENDATIONS FOR FUTURE WORK: HOW GAIT ANALYSIS CAN GUIDE THE DEVELOPMENT OF SURGICAL TECHNIQUES Double Bundle In the past few years, the rotational role of the ACL has been studied more thoroughly. Recent cadaveric studies of the ACL have shown that it consists of two major components, the anteromedial (AM) bundle and the posterolateral (PL) bundle (Fig. 80-3). The two-bundle description of the ACL has been accepted as a basis for understanding the function of the ACL. The ACL does not function as a simple band of fibers with constant tension as the knee moves; the two bundles seem to exhibit different tension patterns, and they seem to be susceptible to different forces. When the knee is extended, the PL bundle is tight and the AM bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL takes a more horizontal orientation, causing the AM bundle to tighten and the PM bundle to loosen.79 However, it seems that this structural morphology of the ACL cannot be restored with the common ACL reconstruction techniques. Therefore recent techniques have been developed to better approximate the actual anatomy and physiology of the ACL. One very promising technique is the two-bundle ACL reconstruction. The advantage of two-bundle reconstruction is that it can better replicate the function of the ACL. This is

FIG. 80-3 The posterolateral (PL) and anteromedial (AM) bundles of the anterior cruciate ligament (ACL).

accomplished due to the reinstatement of the two-bundle anatomy of the ligament.80 It is generally agreed that current ACL reconstruction techniques using BPTB or ST/ Gr grafts, anchored in one femoral and one tibial tunnel, achieve this goal partially because they replicate mostly the AM bundle of the ACL. The role of this bundle has been well documented as resisting anterior translational loads.41 However, the PL bundle has received limited attention. A recent in vitro study81 has revealed that the PL bundle is important for the stabilization of the knee against rotational loads. Thus it is possible that the lack of restoration of tibial rotation after an ACL reconstruction is related to the lack of proper replication of the two ACL bundles and specifically of the PL bundle. Recent studies in both human and animals have demonstrated similar results with the twobundle reconstruction technique.80,82–86 However, this conclusion needs to be verified in vivo using gait analysis, as described earlier in our research work. Our experimental protocols can determine whether the double-bundle technique is truly superior in restoring tibial rotation during physical activities. 621

Anterior Cruciate Ligament Reconstruction

Tunnel Positioning Another very promising technique that has been developed recently to better approximate the actual anatomy and physiology of the ACL is the more oblique femoral tunnel placement. A more oblique placement of the femoral tunnel can also affect rotational stability.40,87,88 The basic advantages of this technique are: (1) it is not as surgically demanding as others (i.e., a two-bundle reconstruction) and (2) the only difference from the current techniques is in the setting of the femoral tunnel in a more oblique location (between 9 and 10 o’clock for a right knee). Current techniques use a vertical orientation approximately at the 11-o’clock position (Fig. 80-4). Several studies used in vitro methodology to examine the more oblique placement of the femoral tunnel using either the BPTB40,87 or the ST/Gr autograft.88 They found that the more oblique placement of the femoral tunnel more effectively resisted rotational loads. This can be attributed to the fact that the PL bundle of the ACL is located more horizontally and toward the 9-o’clock position of the femur (for the right leg) and is important for the stabilization of the knee against rotational loads. Thus a more oblique placement can better replicate the PL bundle and result in increased resistive ability to rotational forces. In our studies, the femoral tunnel was placed at the 11-o’clock position. However, we are currently examining the effect of a more horizontal placement of the femoral tunnel on tibial

11 12 10 9

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FIG. 80-4 A schematic of the placement of the femoral tunnel with the “hours” identified for the right knee.

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rotation. We perform reconstructions with both BPTB and the ST/Gr autografts in which the femoral tunnel is placed in a more oblique location and at 9 o’clock. Then we use gait analysis and our experimental protocols to identify whether a more horizontal placement of the femoral tunnel is superior in restoring tibial rotation during physical activities.

SUMMARY In this chapter, we presented how gait analysis and in vivo biomechanics revealed excessive tibial rotation in ACL deficiency. Our experimental work showed that ACL reconstruction with the currently used autografts (BPTB and ST/Gr) cannot restore tibial rotation, as has also been found in activities that are more demanding than walking and involve both anterior and rotational loading of the knee. Based on this research work, we presented a hypothesis for the development of osteoarthritis in both ACL deficient and ACL reconstructed knees. Specifically, we proposed that excessive tibial rotation will lead to abnormal loading of cartilage areas that are not commonly loaded in the healthy knee. Over time, this abnormal loading will lead to osteoarthritis. We also presented how the evaluation of knee stride-tostride variability using nonlinear analysis can be used to quantify dynamic functional knee stability. We proposed an alternative complexity hypothesis model. In this model we hypothesized that there is an optimal healthy amount of knee variability, and decreases or increases due to ACL pathology can result in future knee pathology. We based this proposition on our experimental work that revealed that ACL deficiency results in a more rigid knee, whereas ACL reconstruction results in a noisier knee. In addition, we demonstrated how gait analysis can assist in the improvement and development of new surgical procedures and grafts that could restore not only the pathological anterior drawer, but also the increased tibial rotation. Attempts to achieve this include a more horizontally oriented femoral tunnel or a double-bundle ACL reconstruction. Experimental methodology such as that presented in this chapter can examine the advantages and disadvantages of these different surgical procedures, whether it be the graft material or the tunnel positioning, keeping always in mind the importance of reproducing the actual ACL anatomy during the reconstruction. Finally, additional studies are also needed to verify or refute our theoretical propositions regarding the development of osteoarthritis due to excessive tibial rotation and the generalization of the complexity hypothesis to musculoskeletal pathologies.

Gait Analysis in Anterior Cruciate Ligament Deficient and Reconstructed Knees

References 1. Heier KA, Mack DR, Moseley JB, et al. An analysis of anterior cruciate ligament reconstruction in middle-aged patients. Am J Sports Med 1997;25:527–532. 2. Noyes FR, Barber-Westin SD. A comparison of results in acute and chronic anterior cruciate ligament ruptures of arthroscopically assisted autogenous patellar tendon reconstruction. Am J Sports Med 1997;25:460–471. 3. Chmielewski TL, Rudolph KS, Fitzgerald GK, et al. Biomechanical evidence supporting a differential response to acute ACL injury. Clin Biomech 2001;16:586–591. 4. Chmielewski TL, Rudolph KS, Snyder-Mackler L. Development of dynamic knee stability after acute ACL injury. J Electromyogr Kinesiol 2002;12:267–274. 5. Johansson H, Sjolander P, Sojka P. A sensory role for the cruciate ligaments. Clin Orthop 1991;268:161–175. 6. Rudroff T. Functional capability is enhanced with semitendinosus than patellar tendon ACL repair. Med Sci Sports Exerc 2003;35:1486–1492. 7. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 8. Harter RA, Osternig LR, Singer KM, et al. Long-term evaluation of knee stability and function following surgical reconstruction for anterior cruciate ligament insufficiency. Am J Sports Med 1988;16:434–443. 9. Tegner Y. Strength training in the rehabilitation of cruciate ligament tears. Sports Med 1990;9:129–136. 10. Baker D, Wilson G, Carlyon B. Generality versus specificity: a comparison of dynamic and isometric measures of strength and speedstrength. Eur J Appl Physiol Occup Physiol 1994;68:350–355. 11. Devita P, Hortobagyi T, Barrier J. Gait biomechanics are not normal after anterior cruciate ligament reconstruction and accelerated rehabilitation. Med Sci Sports Exerc 1998;30:1481–1488. 12. Timoney JM, Inman WS, Quesada PM, et al. Return of normal gait patterns after anterior cruciate ligament reconstruction. Am J Sports Med 1993;21:887–889. 13. Berchuck M, Andriacchi TP, Bach BR, et al. Gait adaptations by individuals who have a deficient anterior cruciate ligament. J Bone Joint Surg 1990;72A:871–877. 14. Georgoulis AD, Papadonikolakis A, Papageorgiou CD, et al. Threedimensional tibiofemoral kinematics of the anterior cruciate ligament-deficient and reconstructed knee during walking. Am J Sports Med 2003;31:75–79. 15. Andriacchi TP. Dynamics of pathological motion: applied to the anterior cruciate deficient knee. J Biomech 1990;23:99–105. 16. Andriacchi TP. Functional analysis of pre and post-knee surgery: total knee arthroplasty and ACL reconstruction. J Biomech Eng 1993;115:575–581. 17. DeLuca PA, Davis RB, Ounpuu S, et al. Alterations in surgical decision making in patients with cerebral palsy based on three dimensional gait analysis. J Pediatric Orthopedics 1997;17:608–614. 18. Lee E, Goh J, Bose K. Value of gait analysis in the assessment of surgery in cerebral palsy. Arch Phys Med Rehabil 1992;73:642–646. 19. Winter D, Patla A, Frank J, et al. Biomechanical walking pattern changes in the fit and healthy elderly. Phys Therapy 1990;70:340–347. 20. Harris GF, Wertsch JJ. Procedures for gait analysis. Arch Phys Med Rehab 1994;75:216–225. 21. Reinschmidt C, van den Bogert AJ, Nigg BM, et al. Effect of skin movement on the analysis of skeletal knee joint motion during running. J Biomech 1997;30:729–732. 22. Lafortune MA, Cavanagh PR, Sommer HJ, et al. Three-dimensional kinematics of the human knee during walking. J Biomech 1992;25:347–357. 23. Ishii Y, Terajima K, Terashima S, et al. Three-dimensional kinematics of the human knee with intracortical pin fixation. Clin Orthop 1997;343:144–150.

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24. Lafortune MA. Three-dimensional acceleration of the tibia during walking and running. J Biomech 1991;24:877–886. 25. Cappozzo A, Catani F, Leardini A, et al. Position and orientation in space of bones during movement: experimental artefacts. Clin Biomech 1996;11:90–100. 26. Lucchetti L, Cappozzo A, Cappello A, et al. Skin movement artefact assessment and compensation in the estimation of knee-joint kinematics. J Biomech 1998;31:977–984. 27. Ristanis S, Giakas G, Papageorgiou CD, et al. The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs. Knee Surg Sports Traumatol Arthrosc 2003;11:360–365. 28. Gage JR. Gait analysis. An essential tool in the treatment of cerebral palsy. Clin Orthop 1993;288:6–34. 29. Chambers HG, Sutherland DH. A practical guide to gait analysis. J Am Acad Orthop Surg 2002;10:222–231. 30. Ristanis S, Stergiou N, Patras K, et al. Excessive tibial rotation during high demanding activities is not restored by ACL reconstruction. Arthroscopy 2005;21:1323–1329. 31. Decker M, Torry M, Noonan T, et al. Landing adaptations after ACL reconstruction. Med Sci Sports Exerc 2002;34:1408–1413. 32. McNair P, Marshall R. Landing characteristics in subjects with normal and anterior cruciate ligament deficient knee joints. Arch Phys Med Rehabil 1994;75:584–589. 33. Ristanis S, Stergiou N, Patras K, et al. Follow-up evaluation 2 years after ACL reconstruction with a BPTB graft shows that excessive tibial rotation persists. Clin J Sports Med 2006;16:111–116. 34. Chen L, Cooley V, Rosenberg T. ACL reconstruction with hamstring tendon. Orthop Clin N Am 2003;34:9–18. 35. Hamner DL, Brown CH, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Boint Joint Surg 1999;81A:549–557. 36. Rowden N, Sher D, Rogers G, et al. Anterior cruciate ligament graft fixation. Initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers. Am J Sports Med 1997;25:472–478. 37. Fu FH, Bennett CH, Lattermann C, et al. Current trends in anterior cruciate ligament reconstruction. Part I: biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821–830. 38. Chouliaras V, Ristanis S, Moraiti C, et al. The effectiveness of reconstruction of the ACL with quadrupled hamstrings and bone-patellar tendon-bone autografts. An in-vivo study comparing tibial internalexternal rotation. Am J Sports Med 2007;35:189–196. 39. Georgoulis AD, Ristanis S, Chouliaras V, et al. Tibial rotation is not restored after ACL reconstruction with a hamstring graft. Clin Orthop Relat Res 2007;454:89–94. 40. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304. 41. Kanamori A, Woo SL, Ma CB, et al. The forces in the anterior cruciate ligament and knee kinematics during a simulated pivot shift test: a human cadaveric study using robotic technology. Arthroscopy 2000;16:633–639. 42. Yoo JD, Papannagari R, Park SE, et al. The effect of anterior cruciate ligament reconstruction on knee joint kinematics under simulated muscle loads. Am J Sports Med 2005;33:240–246. 43. Woo SL, Kanamori A, Zeminski J, et al. The effectiveness of reconstruction of the anterior cruciate ligament with hamstrings and patellar tendon. A cadaveric study comparing anterior tibial and rotational loads. J Bone Joint Surg 2002;84A:907–914. 44. Winter DA. Biomechanics of normal and pathological gait: implications for understanding human locomotion control. J Motor Behav 1989;21:337–355. 45. Yack J, Berger RC. Dynamic stability in the elderly: identifying a possible measure. J Gerontol Med Sci 1993;48:225–230.

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Anterior Cruciate Ligament Reconstruction 46. Maki BE. Gait changes in older adults: predictors of falls or indicators of fear? J Am Geriat Soc 1997;45:313–320. 47. Hausdorff JM, Cudkowicz ME, Firtion R, et al. Gait variability and basal ganglia disorders: stride-to-stride variations of gait cycle timing in Parkinson’s disease and Huntington disease. Mov Disord 1998;13:428–437. 48. Amato R. Chaos breaks out at NIH, but order may come out of it. Science 1992;257:1763–1764. 49. Buchman TG, Cobb JP, Lapedes AS, et al. Complex systems analysis: a tool for shock research. Shock 2001;16:248–251. 50. Goldberger AL, Rigney DR, Mietus J, et al. Nonlinear dynamics in sudden cardiac death syndrome: heart rate oscillations and bifurcations. Experentia 1988;44:983–987. 51. Goldstein B, Toweill D, Lai S, et al. Uncoupling of the automatic and cardiovascular systems in acute brain injury. Am J Physiol 1998;257: R1287–R1292. 52. Lanza GA, Guido V, Galeazzi MM, et al. Prognostic role of heart rate variability in patients with a recent acute myocardial infarction. Am J Cardiol 1998;82:1323–1328. 53. Slutzky MW, Cvitanovic P, Mogul DJ. Deterministic chaos and noise in three in vivo hippocampal models of epilepsy. Ann Biomed Eng 2001;29:607–618. 54. Toweill DL, Goldstein B. Linear and nonlinear dynamics and the pathophysiology of shock. New Horiz 1998;6:155–168. 55. Wagner CD, Nafz B, Persson PB. Chaos in blood pressure control. Cardiovasc Res 1996;31:380–387. 56. Pool R. Is it healthy to be chaotic? Science 1989;243:604–607. 57. Lipsitz LA, Goldberger AL. Loss of complexity and aging. J Am Med Assoc 1992;267:1806–1809. 58. Goldberger AL, Amaral LAN, Hausdorff JM, et al. Fractal dynamics in physiology: alterations with disease and aging. Proc Natl Acad Sci 2002;99:2466–2472. 59. Hausdorff JM, Peng CK, Landin Z, et al. Is walking a random walk? Evidence for long-range correlations in stride interval of human gait. J Appl Physiol 1995;78:349–358. 60. Buzzi UH, Stergiou N, Kurz MJ, et al. Nonlinear dynamics indicates aging affects variability during gait. Clin Biomech 2003; 18:435–443. 61. Stergiou N, Buzzi UH, Kurz MJ, et al. Nonlinear tools in human movement. In Stergiou N (ed). Innovative analyses of human movement. Champaign, IL, 2004, Human Kinetics, pp 63–90. 62. Georgoulis AD, Moraiti C, Ristanis S, et al. A novel approach to measure variability in the anterior cruciate ligament deficient knee during walking: the use of Approximate Entropy in orthopaedics. J Clin Monit Comput 2006;20:11–18. 63. Moraiti C, Vasiliadis H, Tzimas V, et al In Patellar tendon vs hamstrings graft: variability changes in knee flexion/extension movement patterns during walking. Presented at the 12th meeting of ESSKA 2000 Congress. Innsbruck, Austria, May 24–27, 2006. 64. Mankin HJ. The response of articular cartilage to mechanical injury [current concepts]. J Bone Joint Surg 1982;64A:460–466. 65. Finsterbush A, Frankl U, Matan Y, et al. Secondary damage to the knee after isolated injury of the anterior cruciate ligament. Am J Sports Med 1990;18:475–479. 66. McDaniel WJ, Dameron TJ. The untreated anterior cruciate ligament rupture. Clin Orthop 1983;172:158–163. 67. Noyes F, Matthews D, Mooar P, et al. The symptomatic anterior cruciate-deficient knee. Part II: the results of rehabilitation, activity modification, and counseling on functional disability. J Bone Joint Surg 1983;65A:163–174. 68. Noyes F, Mooar P, Matthews D, et al. The symptomatic anterior cruciate-deficient knee. Part I: the long-term functional disability

624

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70.

71. 72.

73.

74.

75.

76.

77. 78. 79.

80.

81.

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in athletically active individuals. J Bone Joint Surg 1983; 65B:154–162. Daniel DM, Stone ML, Dobson BE, et al. Fate of the ACLinjured patient: a prospective outcome study. Am J Sports Med 1994;22:632–644. Asano H, Muneta T, Ikeda H, et al. Arthroscopic evaluation of the articular cartilage after anterior cruciate ligament reconstruction: a short-term prospective study of 105 patients. Arthroscopy 2004;20:474–481. Wong M, Carter DR. Articular cartilage functional histomorphology and mechanobiology: a research perspective. Bone 2003;33:1–13. Jurvelin J, Kiviranta I, Tammi M, et al. Effect of physical exercise on indentation stiffness of articular cartilage in the canine knee. Int J Sports Med 1986;7:106–110. Saamanen AM, Tammi M, Kiviranta I, et al. Running exercise as a modulatory of proteoglycan matrix in the articular cartilage of young rabbits. Int J Sports Med 1988;9:127–133. Kiviranta I, Tammi M, Jurvelin J, et al. Moderate running exercise augments glycosaminoglycans and thickness of articular cartilage in the knee joint of young beagle dogs. J Orthop Res 1988;6:188–195. Bullogh PG. The pathology of osteoarthritis. In Moskowitz R, Howell D, Goldberg V, et al (eds). Osteoarthritis: diagnosis and medical/surgical management. Philadelphia, 1992, Saunders, pp 36–69. Kleiger RE, Miller JP, Bigger JT, et al. Decreased heart rate variability and its association with increased mortality after acute myocardial infarction. Am J Cardiol 1987;59:256–262. Kaplan DT, Furman MI, Pincus SM, et al. Aging and the complexity of cardiovascular dynamics. Biophys J 1991;59:945–949. Bhattacharya J. Complexity analysis of spontaneous EEG. Acta Neurobiol Exp (Wars) 2000;60:495–501. Amis AA, Dawkins GP. Functional anatomy of the anterior cruciate ligament. Fibre bundle actions related to ligament replacements and injuries. J Bone Joint Surg 1991;73B:260–267. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. Gabriel MT, Wong EK, Woo SL, et al. Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads. J Orthop Res 2004;22:85–89. Radford WJ, Amis AA, Kempson SA, et al. A comparative study of single- and double-bundle ACL reconstructions in sheep. Knee Surg Sports Traumatol Arthrosc 1994;2:94–99. Muneta T, Sekiya I, Yagishita K, et al. Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with endobuttons: operative technique and preliminary results. Arthroscopy 1999;15:618–624. Zaricznyj B. Reconstruction of the anterior cruciate ligament of the knee using a doubled tendon graft. Clin Orthop 1987;220:162–175. Mae T, Shino K, Miyama T, et al. Single- versus two-femoral socket anterior cruciate ligament reconstruction technique: biomechanical analysis using a robotic simulator. Arthroscopy 2001;17:708–716. Guardamagna L, Seedhom BB, Ostell AE. Double-bundle reconstruction of the ACL using a synthetic implant: a cadaveric study of knee laxity. J Orthop Sci 2004;9:372–379. Scopp JM, Jasper LE, Belkoff SM, et al. The effect of oblique femoral tunnel placement on rotational constraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294–299. Musahl V, Plakseychuk A, VanScyoc A, et al. Varying femoral tunnels between the anatomical footprint and isometric positions. Effect on kinematics of the ACL reconstructed knee. Am J Sports Med 2005;33:1–7.

Growth Factors and Other New Methods for Graft-Healing Enhancement Anterior cruciate ligament (ACL) reconstruction using tendon autograft has been greatly improved over the last 2 decades.1 In ACL reconstruction, however, the strength of the grafted tendon is reduced in the early phase after surgery, and then it gradually increases.2–4 A problem is that this graft remodeling occurs very slowly.5 The slow graft maturation may result in graft failure or elongation during the postoperative rehabilitation period due to unknown causes. In addition, a firm attachment of a tendon graft to the bone is a significant factor for success in ACL reconstruction. In procedures using a hamstring tendon graft, however, the anchoring strength of the soft tissue in a bone tunnel is the weakest in the femur–graft–tibia complex in the early phase after surgery.6 To improve these problems after ACL reconstruction in the near future, we should try to develop a new strategy to accelerate the intraarticular and intraosseous remodeling of the tendon graft. This may enable more aggressive rehabilitation and an earlier return to rigorous sports for patients with ACL reconstruction. In this chapter, the authors will review recent experimental studies that are intended to enhance intraarticular and intraosseous graft healing after ACL reconstruction using growth factors, gene therapy, and cell-based therapy.

BASIC KNOWLEDGE TO ENHANCE THE GRAFT REMODELING IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION In ACL reconstruction, intrinsic fibroblasts of the tendon graft are necrotized immediately after

transplantation, and then numerous extrinsic fibroblasts infiltrate the graft with revascularization.7,8 However, it is possible that the cell infiltration into a core portion of the graft occasionally occurs very slowly. Delay et al5 reported a clinical case in which the core portion of the patellar tendon graft still remained necrotic even at the 18-month period after ligament reconstruction. On the other hand, biomechanically, the mechanical properties of the graft deteriorate in the early phase after transplantation and then are very gradually restored over a long period.2–4 Concerning the graft deterioration mechanism, the fibroblast necrosis itself does not deteriorate the mechanical properties of the tendon matrix, but extrinsic fibroblasts proliferating after the necrosis reduce the strength properties.9 In the extrinsic fibroblasts, type III collagen is overexpressed even under physiological stress in areas where extrinsic fibroblasts infiltrate.10 In the matrix of the autograft after transplantation, ultrastructurally, fibrils having a diameter less than 90 nm predominantly increase in the graft matrix, and these fibrils with small diameters still remain predominant at the 4-year period after surgery.11 Such ultrastructural changes due to type III collagen production are considered to be one of the causes of mechanical deterioration of autografts. What molecular mechanisms control the autograft remodeling? In a rabbit ACL reconstruction model, vascular endothelial growth factor (VEGF) is overexpressed in the extrinsic fibroblasts at 2 weeks after graft implantation, followed by vascular formation at 3 weeks.12

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Anterior Cruciate Ligament Reconstruction This fact shows that revascularization in the graft is induced by VEGF produced in the fibroblasts. On the other hand, basic fibroblast growth factor, transforming growth factor (TGF)-b, and platelet-derived growth factor (PDGF) are overexpressed in the autogenous patellar tendon graft used to reconstruct the ACL in the canine model, reaching their greatest expression 3 weeks after implantation.13 This fact suggests that a complex growth factor network controls the fibroblasts, resulting in remodeling of the graft matrix,14,15 and implies that control of the fibroblasts using growth factors is a potential strategy to accelerate the graft remodeling after ACL reconstruction.

ENHANCEMENT OF GRAFT HEALING WITH GROWTH FACTORS Intraarticular Healing PDGF-BB It has been known that PDGF-BB enhances proliferation and migration of ligament fibroblasts in vitro.16,17 In addition, an in vivo rabbit study showed that the strong expression of PDGF correlates with the observed increased cellularity around the wound site in the medial collateral ligament (MCL), suggesting potent mitogenic and chemotactic properties of PDGF in vivo.18 Concerning the in vivo effect of application of PDGF-BB on ligamentous tissues, Woo et al19 and Hildebrand et al20 described that 20-mg PDGFBB alone is the most effective agent to enhance the extraarticular MCL healing in the rabbit. Regarding intraarticular ACL reconstruction, Weiler et al21 applied PDGF-BB of approximately 60 mg using coated sutures as a vehicle on the flexor tendon autograft in a sheep ACL reconstruction model. They showed that the PDGF-BB application significantly increased the load to failure and vascular density of the graft at 6 weeks after ACL reconstruction, although they found no significant effects at 24 weeks. However, Nagumo et al22 investigated the effect of PDGF-BB using fibrin sealant as a carrier on the in situ frozen-thawed rabbit ACL, an idealized intraarticular autograft model.23–25 They reported that an application of 4-mg PDGF-BB did not significantly affect the mechanical properties of the frozen-thawed ACL at 12 weeks. Hildebrand et al20 suggested that the dose is critical to evaluate the effect of growth factors on ligament healing. Application of a high dose of PDGF-BB appears to be effective for MCL healing. However, the effect of PDGF-BB in ACL reconstruction is controversial.

VEGF VEGF is a potent mediator of angiogenesis, which involves activation, migration, and proliferation of endothelial cells, 626

in various pathological conditions.26 A rabbit study showed that extrinsic cells newly proliferating in the necrotized tendon graft express VEGF at 3 weeks after surgery, when the revascularization does not occur.12 This finding suggests the high possibility that an application of VEGF to the necrotized tendon graft enhances angiogenesis in the graft and accelerates remodeling of the graft. Ju et al27 histologically and mechanically examined the effect of an application of 30-mg VEGF to the in situ frozen-thawed rabbit ACL. The application of VEGF significantly enhanced vascular endothelial cell infiltration and revascularization in the ACL at 3 and 12 weeks, respectively (Fig. 81-1). On the other hand, the application provided no significant effect on the mechanical properties of the ACL at 12 weeks, although the mechanical properties of the in situ frozenthawed rabbit ACL were significantly weaker than those of the normal ACL at 12 weeks. Thus VEGF has a potential to be used as a treatment to enhance only revascularization of the autograft after ACL reconstruction surgery.

TGF-b and EGF A number of in vitro studies have shown that TGF-b enhances collagen and noncollagenous protein synthesis in fibroblasts.28–30 EGF also stimulates fibroblast proliferation in vitro.31 A combined application of these two growth factors enhances these effects.32 Sakai et al25 examined in vivo effects of an application of TGF-b and EGF on the in situ frozen-thawed ACL, using fibrin sealant as a vehicle. They found that a combined application of 4-ng TGF-b and 100-ng EGF significantly inhibited the natural deterioration that occurred in this autograft model with significant reduction of the water content and significant changes of the ultrastructural profile. Azuma et al33 investigated the effect of the timing of this combined application on the same rabbit model. They reported that the effect was significantly greater when 4-ng TGF-b and 100-ng EGF were applied at 3 weeks than when they were applied at 0 and 6 weeks. This study suggested that the timing is critical in application of these growth factors. Recently, Nagumo et al22 distinguished between the effect of 4-ng TGF-b and the effect of 100-ng EGF on the autograft model. According to them, the effect of 100-ng EGF was not significant, but the effect of 4-ng TGF-b was significant. Concerning an intraarticular application of TGF-b and EGF on the bone–patellar tendon–bone (BPTB) autograft in a canine ACL reconstruction model, Yasuda et al34 evaluated the effect on the structural properties of the graft. They stated that a combined application of 4-ng TGF-b and 100-ng EGF significantly inhibited the natural reduction of the structural properties of the autograft at 12 weeks after ACL reconstruction.

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FIG. 81-1 Immunohistochemistry for CD31 to identify vascular endothelial cells in the anterior cruciate ligament (ACL) after the in situ freeze-thaw treatment without vascular endothelial growth factor (VEGF) application (A, 3 weeks; B, 6 weeks; C, 12 weeks) and with VEGF application (D, 3 weeks; E, 6 weeks; F, 12 weeks). A, In the ACL after in situ freeze-thaw treatment, few vascular endothelial cells were found at 3 weeks. B, At 6 weeks, several vascular endothelial cells formed vessels in the superficial portion of the ACL. C, The number of the vessels with endothelial cells decreased in the ACLs from 6 weeks to 12 weeks. D, Several vessels formed by endothelial cells were observed in the superficial portion of the ACL with VEGF application at 3 weeks after the in situ freeze-thaw treatment. E and F, The vessels with endothelial cells in the ACL with VEGF application were more abundant than those in the ACL without VEGF application until 12 weeks. (From Ju YJ, Tohyama H, Kondo E, et al. Effects of local administration of vascular endothelial growth factor on properties of the in situ frozen-thawed anterior cruciate ligament in rabbits. Am J Sports Med 2006;34:84–91.)

Intraosseous Healing Bone Morphogenetic Proteins The process of tendon–bone healing involves bone ingrowth into the interface tissue between the tendon and bone.35 Bone morphogenetic proteins (BMPs) are members of the TGF-b superfamily and are factors that have a strong osteoinductive and osteogenic capacity.36 They induce endochondral bone formation at extraskeletal sites. They are mostly expressed at sites of epithelial–mesenchymal interaction and serve as signaling molecules during mammalian embryogenesis and morphogenesis, suggesting their capability for differentiation of mesenchymal cells into chondrocytes and osteoblasts. The BMPs have been successfully used to regenerate bone defects, to stimulate bone ingrowth into soft tissues and metal implants, and to regenerate articular cartilage defects in large animals.36 Concerning intraosseous healing of the tendon, Rodeo et al37 showed that tendon healing in a bone tunnel was enhanced by BMP-2 in the canine. Their histological analysis showed that the BMP-2 treatment resulted in earlier and more abundant bone ingrowth into the tendon–bone

interface and that it biomechanically increased the anchoring strength. Anderson et al38 described that a bone-derived extract (Bone Protein, Sulzer Biologics, Wheat Ridge, CO) was effective in augmenting healing of a tendon graft within a bone tunnel in a rabbit ACL reconstruction model. Recently, Mihelic et al39 reported that BMP-7 (osteogenic protein-1) induced the new bone formation at the bone– tendon interface, creating a dense trabecular network in a sheep ACL reconstruction model. Their mechanical testing showed greater strength in the knees treated with BMP-7 than in control specimens. Thus BMPs have potential growth factors to enhance intraosseous graft healing.

TGF-b TGF-b is a multifunctional growth factor that induces new matrix synthesis in numerous types of cells. It has been shown that TGF-b can enhance bone ingrowth into biomaterial implants.40,41 Recently, Yamazaki et al42 found that administration of exogenous TGF-b1 significantly increased the bonding strength of the flexor tendon graft to the tunnel wall at 3 weeks in a canine ACL replacement model. This result 627

Anterior Cruciate Ligament Reconstruction

B G B

G

A

B

FIG. 81-2 The new bone formation at the anterior wall of the bone tunnel at 3 weeks after anterior cruciate ligament (ACL) reconstruction using flexor tendon graft. The rectangle (500  1000 mm) was drawn in the adjacent trabecular area to the tunnel wall. The newly formed bone was generated more richly in the interface with transforming growth factor (TGF)-b application (A) than in that without TGF-b application (B). (B, Bone; G, granulation tissue in tendon–bone gap) (hematoxylin and eosin, original magnification 20). (From Yamazaki S, Yasuda K, Tomita F, et al. The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of anterior cruciate ligament in dogs. Arthroscopy 2005;21:1034–1041.)

was accompanied by the histological findings that the administration appeared to enhance not only synthesis or maturation of the perpendicular collagen fibers connecting the graft to the bone, but also new bone formation from the tunnel wall (Fig. 81-2). Thus, TGF-b1 also has the potential to enhance intraosseous graft healing.

ENHANCEMENT OF GRAFT HEALING WITH GENE THERAPY Gene therapy approaches may represent a new alternative in delivering these specific growth factors to the grafted tendon after ACL reconstruction.43 Martinek et al44 examined the capacity of BMP-2 gene transfer to improve the integration of semitendinosus tendon grafts at the tendon–bone interface after reconstruction of the ACL in rabbits. They found that in the intraosseous portion of the grafts, the number of 628

infected cells did not decrease until 8 weeks after surgery. Moreover, a number of transduced cells were found in the deeper layers of the tendon in the bone tunnel. In the AdBMP-2–infected ACL graft, the tendon–bone interface in the osseous tunnel was similar to that of a normal ACL insertion. The pullout load and the stiffness were significantly greater in the AdBMP-2–transduced graft than the control graft. Concerning gene therapy for the intraarticular portion of the graft healing after ACL reconstruction, however, Gerich et al45 evaluated methods for gene delivery to patellar tendons in the rabbits using the lacZ marker gene. They found that after injection of the adenovirus, high-level expression of lacZ was observed only in the portion adjacent to the injection site. Martinek et al44 reported that in the intraarticular portion of the AdLacZ-infected grafts, infected cells were observed only in the surface portion, and the number of the cells decreased between 2 and 8 weeks

Growth Factors and Other New Methods for Graft-Healing Enhancement after ACL reconstruction with the autologous semitendinosus tendon graft in the rabbit. Therefore it seems difficult to directly transfer genes for specific proteins to the core portion of the intraarticular graft and to maintain the number of the cells for a long period. Thus it may be difficult to successfully perform gene therapy by itself to enhance the graft healing of the intraarticular portion in ACL reconstruction. In 1999, Menetrey et al46 reported a myoblast-mediated gene transfer method for a persistent expression of selected growth factors to enhance ACL healing following injury.

ENHANCEMENT OF GRAFT HEALING WITH CELL-BASED THERAPY TGF-b1 and EGF significantly inhibited the deterioration of the mechanical properties of the BPTB autograft in ACL reconstruction.34 Nagumo et al22 suggested that only TGFb1 is a key in this effect on the intraarticular graft. However, Mi et al47 reported that gene transfer of TGF-b induced arthritic changes of the articular cartilage in the knee joint. Thus intraarticular administration of TGF-b is considered to be unsuitable for clinical application with an ACL reconstruction procedure. Therefore Okuizumi et al48 conducted the rabbit study to clarify the effect of cell therapy with autologous synovial tissue–derived fibroblasts activated by TGF-b1 on the necrotized ACL (Fig. 81-3). They wrapped the fibrin glue with autologous synovial tissue–derived fibroblasts after TGF-b stimulation around the necrotized ACL following the freeze-thaw treatment. Histological observation found that implantation of fibroblasts after TGF-b stimulation accelerated cellular infiltration into the ACL following fibroblast necrosis (Fig. 81-4). Biomechanically, the transplantation of synovial tissue–derived autologous fibroblasts activated by TGF-b inhibited deterioration in the tangent modulus of the ACL after the freeze-thaw treatment. Therefore this cell-based therapy using fibroblasts activated by TGF-b may be a potential solution against this problem in order to inhibit the deterioration of the mechanical properties of the graft after ACL reconstruction. Mesenchymal progenitor cells (MPCs) or mesenchymal stem cells (MSCs) also have a potential for cell therapy. For example, an autologous MSC–collagen graft could improve the quality as well as accelerate the rate of healing after the defect of the patellar tendon in rabbits.49 Recently, Ouyang et al50 reported the efficacy of using a large number of MSCs to enhance tendon–bone healing in a rabbit model. They found that introduction of a large number of MSCs to the bone tunnel improves the insertion healing of tendon to bone in a rabbit model through formation of

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Synovial tissues harvested from the left suprapatellar bursa

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Day 28

Implantation to the frozen-thawed ACL

FIG. 81-3 The experimental protocol of the cell-based therapy with autologous synovial tissue–derived fibroblasts with transforming growth factor (TGF)-b application. ACL, Anterior cruciate ligament. (From Okuizumi T, Tohyama H, Kondo E, et al. The effect of cell-based therapy with autologous synovial fibroblasts activated by exogenous TGF-beta1 on the in situ frozenthawed anterior cruciate ligament. J Orthop Sci 2004;9:488–494.)

fibrocartilaginous attachment at early time points. However, there are no reports on application of the cell-based therapy with MPCs or MSCs for ACL reconstruction at present.

SUMMARY Recent experimental studies have suggested that application of growth factors, in particular TGF-b, is a possible strategy to prevent graft deterioration in ACL reconstruction and that several types of BMPs and TGF-b enhances tendon– bone healing in animal models. Gene therapy and cell-based approaches may represent new alternatives in delivering these specific growth factors to the grafted tendon and the interface between the graft and the bone after ACL reconstruction. The recent advancements in ACL graft biology may bring new strategies and additional therapeutic options to accelerate the remodeling of the graft after ACL reconstruction.

629

Anterior Cruciate Ligament Reconstruction

FIG. 81-4 Histology of the anterior cruciate ligament (ACL) at 12 weeks after the in situ freeze-thaw treatment and cell therapy with transforming growth factor (TGF)-b application (A) and without TGF-b application (B). (From Okuizumi T, Tohyama H, Kondo E, et al. The effect of cell-based therapy with autologous synovial fibroblasts activated by exogenous TGF-beta1 on the in situ frozen-thawed anterior cruciate ligament. J Orthop Sci 2004;9:488–494.)

References 1. Fu FH, Bennett CH, Ma CB, et al. Current trends in anterior cruciate ligament reconstruction. Part II. Operative procedures and clinical correlations. Am J Sports Med 2000;28:124–130. 2. Clancy WG Jr, Narechania RG, Rosenberg TD, et al. Anterior and posterior cruciate ligament reconstruction in rhesus monkeys. J Bone Joint Surg 1981;63A:1270–1284. 3. Butler DL, Grood ES, Noyes FR, et al. Mechanical properties of primate vascularized vs. nonvascularized patellar tendon grafts; changes over time. J Orthop Res 1989;7:68–79. 4. Ballock RT, Woo SL, Lyon RM, et al. Use of patellar tendon autograft for anterior cruciate ligament reconstruction in the rabbit: a long-term histologic and biomechanical study. J Orthop Res 1989;7:474–485. 5. Delay BS, McGrath BE, Mindell ER. Observation on a retrieved patellar tendon autograft used to reconstruct the anterior cruciate ligament. A case report. J Bone Joint Surg 2002;84A:1433–1438. 6. Tomita F, Yasuda K, Mikami S, et al. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bonepatellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy 2001;17:461–476. 7. Arnoczky SP, Tarvin GB, Marshall JL. Anterior cruciate ligament replacement using patellar tendon. An evaluation of graft revascularization in the dog. J Bone Joint Surg 1982;64A:217–224. 8. Amiel D, Kleiner JB, Akeson WH. The natural history of the anterior cruciate ligament autograft of patellar tendon origin. Am J Sports Med 1986;14:449–462. 9. Tohyama H, Yasuda K. Extrinsic cell infiltration and revascularization accelerate mechanical deterioration of the patellar tendon after fibroblast necrosis. J Biomech Eng 2000;122:594–599. 10. Tohyama H, Yasuda K, Uchida H, et al. Is the increase in type III collagen of the patellar tendon graft after ligament reconstruction really caused by “ligamentization” of the graft? Knee Surg Sports Traumatol Arthrosc 2006;14:1270–1277. 11. Oakes BW. Collagen ultrastructure in the normal ACL and in ACL graft. In Jackson DW (ed): The anterior cruciate ligament. Current and future concepts. New York, 1993, Raven Press, pp 209–217. 12. Yoshikawa T, Tohyama H, Enomoto H, et al. Expression of vascular endothelial growth factor and angiogenesis in patellar tendon grafts in

630

13.

14. 15. 16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

the early phase after anterior cruciate ligament reconstruction.. Knee Surg Sports Traumatol Arthrosc 2006;14:804–810. Kuroda R, Kurosaka M, Yoshiya S, et al. Localization of growth factors in the reconstructed anterior cruciate ligament: immunohistological study in dogs. Knee Surg Sports Traumatol Arthrosc 2000;8:120–126. Koski JA, Ibarra C, Rodeo SA. Tissue-engineered ligament: cells, matrix, and growth factors. Orthop Clin North Am 2000;31:437–452. Woo SL, Hildebrand K, Watanabe N, et al. Tissue engineering of ligament and tendon healing. Clin Orthop Relat Res 1999;367:S312–S323. Schmidt CC, Georgescu HI, Kwoh CK, et al. Effect of growth factors on the proliferation of fibroblasts from the medial collateral and anterior cruciate ligaments. J Orthop Res 1995;13:184–190. Kobayashi K, Healey RM, Sah RL, et al. Novel method for the quantitative assessment of cell migration: a study on the motility of rabbit anterior cruciate (ACL) and medial collateral ligament (MCL) cells. Tissue Eng 2000;6:29–38. Lee J, Harwood FL, Akeson WH, et al. Growth factor expression in healing rabbit medial collateral and anterior cruciate ligaments. Iowa Orthop J 1998;18:19–25. Woo SL, Smith DW, Hildebrand KA, et al. Engineering the healing of the rabbit medial collateral ligament. Med Biol Eng Comput 1998;36:359–364. Hildebrand KA, Woo SL, Smith DW, et al. The effects of plateletderived growth factor-BB on healing of the rabbit medial collateral ligament. An in vivo study. Am J Sports Med 1998;26:549–554. Weiler A, Forster C, Hunt P, et al. The influence of locally applied platelet-derived growth factor-BB on free tendon graft remodeling after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:881–891. Nagumo A, Yasuda K, Numazaki H, et al. Effects of separate application of three growth factors (TGF-b1, EGF, and PDGF-BB) on mechanical properties of the in situ frozen-thawed anterior cruciate ligament. Clin Biomech (Bristol, Avon) 2005;20:283–290. Jackson DW, Grood ES, Cohn BT, et al. The effects of in situ freezing on the anterior cruciate ligament. An experimental study in goats. J Bone Joint Surg 1991;73A:201–213. Katsuragi R, Yasuda K, Tsujino J, et al. The effect of nonphysiologically high initial tension on the mechanical properties of in situ frozen anterior cruciate ligament in a canine model. Am J Sports Med 2000;28:47–56. Sakai T, Yasuda K, Tohyama H, et al. Effects of combined administration of transforming growth factor-beta1 and epidermal growth

Growth Factors and Other New Methods for Graft-Healing Enhancement

26. 27.

28.

29.

30. 31.

32.

33.

34.

35.

36.

37.

38.

factor on properties of the in situ frozen anterior cruciate ligament in rabbits. J Orthop Res 2002;20:1345–1351. Ferrara N, Davis-Smyth T. The biology of vascular endothelial growth factor. Endocr Rev 1997;18:4–25. Ju YJ, Tohyama H, Kondo E, et al. Effects of local administration of vascular endothelial growth factor on properties of the in situ frozen-thawed anterior cruciate ligament in rabbits. Am J Sports Med 2006;34:84–91. DesRosiers EA, Yahia L, Rivard CH. Proliferative and matrix synthesis response of canine anterior cruciate ligament fibroblasts submitted to combined growth factors. J Orthop Res 1996;14:200–208. Deie M, Marui T, Allen CR, et al. The effects of age on rabbit MCL fibroblast matrix synthesis in response to TGF-beta 1 or EGF. Mech Aging Dev 1997;97:121–130. Marui T, Niyibizi C, Georgescu HI, et al. Effect of growth factors on matrix synthesis by ligament fibroblasts. J Orthop Res 1997;15:18–23. Scherping SC Jr, Schmidt CC, Georgescu HI, et al. Effect of growth factors on the proliferation of ligament fibroblasts from skeletally mature rabbits. Connect Tissue Res 1997;36:1–8. Assoian RK, Frolik CA, Roberts AB, et al. Transforming growth factor-beta controls receptor levels for epidermal growth factor in NRK fibroblasts. Cell 1984;36:35–41. Azuma H, Yasuda K, Tohyama H, et al. Timing of administration of transforming growth factor-beta and epidermal growth factor influences the effect on material properties of the in situ frozen-thawed anterior cruciate ligament. J Biomech 2003;6:373–381. Yasuda K, Tomita F, Yamazaki S, et al. The effect of growth factors on biomechanical properties of the bone-patellar tendon-bone graft after anterior cruciate ligament reconstruction: a canine model study. Am J Sports Med 2004;32:870–880. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg 1993;75:1795–1803. Termaat MF, Den Boer FC, Bakker FC, et al. Bone morphogenetic proteins. Development and clinical efficacy in the treatment of fractures and bone defects. J Bone Joint Surg 2005;87:1367–1378. Rodeo SA, Suzuki K, Deng XH, et al. Use of recombinant human bone morphogenetic protein-2 to enhance tendon healing in a bone tunnel. Am J Sports Med 1999;27:476–488. Anderson K, Seneviratne AM, Izawa K, et al. Augmentation of tendon healing in an intraarticular bone tunnel with use of a bone growth factor. Am J Sports Med 2001;29:689–698.

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39. Mihelic R, Pecina M, Jelic M, et al. Bone morphogenetic protein-7 (osteogenic protein-1) promotes tendon graft integration in anterior cruciate ligament reconstruction in sheep. Am J Sports Med 2004;32:1619–1625. 40. Lind M, Overgaard S, Soballe K, et al. Transforming growth factorbeta 1 enhances bone healing to unloaded tricalcium phosphate coated implants: an experimental study in dogs. J Orthop Res 1996;14:343–350. 41. Sumner DR, Turner TM, Purchio AF, et al. Enhancement of bone ingrowth by transforming growth factor-beta. J Bone Joint Surg 1995;77A:1135–1147. 42. Yamazaki S, Yasuda K, Tomita F, et al. The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of anterior cruciate ligament in dogs. Arthroscopy 2005;21:1034–1041. 43. Evans CH, Robbins PD. Genetically augmented tissue engineering of the musculoskeletal system. Clin Orthop Relat Res 1999;367: S410–S418. 44. Martinek V, Latterman C, Usas A, et al. Enhancement of tendonbone integration of anterior cruciate ligament grafts with bone morphogenetic protein-2 gene transfer: a histological and biomechanical study. J Bone Joint Surg 2002;84A:1123–1131. 45. Gerich TG, Kang R, Fu FH, et al. Gene transfer to the rabbit patellar tendon: potential for genetic enhancement of tendon and ligament healing. Gene Ther 1996;3:1089–1093. 46. Menetrey J, Kasemkijwattana C, Day CS, et al. Direct-, fibroblastand myoblast-mediated gene transfer to the anterior cruciate ligament. Tissue Eng 1999;5:435–442. 47. Mi Z, Ghivizzani SC, Lechman E, et al. Adverse effects of adenovirus-mediated gene transfer of human transforming growth factor beta 1 into rabbit knees. Arthritis Res Ther 2003;5:R132–R139. 48. Okuizumi T, Tohyama H, Kondo E, et al. The effect of cell-based therapy with autologous synovial fibroblasts activated by exogenous TGF-beta1 on the in situ frozen-thawed anterior cruciate ligament. J Orthop Sci 2004;9:488–494. 49. Awad HA, Butler DL, Boivin GP, et al. Autologous mesenchymal stem cell-mediated repair of tendon. Tissue Eng 1999;5:267–277. 50. Ouyang HW, Goh JC, Lee EH. Viability of allogeneic bone marrow stromal cells following local delivery into patella tendon in rabbit model. Cell Transplant 2004;13:649–657.

631

Index Page numbers followed by f, t, or b indicate figures, tables, or boxed material, respectively.

A AATB. See American Association of Tissue Banks ABC graft, 88 Abductor strengthening, 524 ACL. See Anterior cruciate ligament Active heel-lift exercise, 515 Adductor strengthening, 524 Allografts, 80 anterior knee problems and, 610 BPTB, complications, 561–563 hamstring, surgical preparation, 236 increased laxity and, 562–563 chemical treatments, 562 donor age, 562 freezing, 562 immunological response, 563 increased shelf time, 563 radiation sterilization, 562 infection and, 557 bacterial, 557 viral, 557 IntraFix with, 343 meniscal, 493–499 methods, 84 morbidity, 561–562 delayed graft failure, 561 disease transmission, 562 graft failure, 561 graft laxity, 561 infection, 562 osteochondral, 496 peroneus, 313 for posterolateral augmentation, 473 rehabilitation, 525 in revisions, 447 stability, 548 strength comparisons, 84 tendo-Achilles, 313 tibial, 208 surgical preparation, 236 tibialis, 313

Allografts (Continued ) graft sleeve with, 335 preparation of, 340 in tunnel widening, 577 Alpine skiing, 24, 32 AM bundle. See Anteromedial bundle American Association of Tissue Banks (AATB), 454 AMRI. See Anterolateral rotatory instability; Anteromedial rotatory instability Anatomical fixation, 284 Anatomical risk factors, 19 notch width of, 19 studies evaluating, 21 Q angle and, 19 Anesthesia, 472 Angiography, 593f CT, 594 MRI, 595 Animal studies, graft tunnel healing, 418 authors’ experience, 421 bone quality in, 420 fixation technique, 420 gap size, 420 graft types, 419 mechanical stresses, 421 Anterior cruciate ligament (ACL), 3 anatomy, 3, 141f AM bundle, 4 crossing pattern, 6 development of, 4 historical descriptions of, 3 insertion site, 4 PL bundle, 4 tensioning pattern, 6 attachment points, 143, 145 biomechanics, 7, 15 anterior-posterior translation control, 9 historical studies on, 7 rotational stability, 9 in surgery, 9 complete tears, deficiency, 60 bracing in, 64

633

Index Anterior cruciate ligament (ACL) (Continued ) hamstrings in, 63 natural history of, 70 quadriceps in, 63 rehabilitation, 64 fetal, 4f, 5 graft tensioning, 399–404 hamstring grafts postoperative rehabilitation protocol, 339 tibial fixation for, 211–216 healing, 477 histology of, 630 injury LCL combined, 477–483 MCL combined, 477–483 osteoarthritis following, 69–74 PCL combined, 477–483 prevention studies, 43 ligament tears acute, 53 chronic, 53, 54 partial, 53 PCL tears v., 54 physical exam, 54 loading, 13–15 knee flexion and, 14 noncontact injuries, 12–15 anatomical risk factors, 19 environmental risk factors, 18 familial tendency to, 25 hormonal risk factors, 20 neuromuscular, 23 normal, reconstructions, 79 additive costs, 80 all-inside, 300f anatomical double-bundle, 144, 168–177 anatomical double-bundle, double-stranded hamstring autografts, 155–159 anatomical double-bundle with semitendinosus hamstring tendon graft, 161–166 anatomical single-bundle, 144 anterior knee problems after, 598, anteromedial portal for, 129–131 arthroscopic, 111, 163 arthrosis following, 71, 72 with autologous chondrocyte implantation, 493–499 autologous hamstring tendon, 427–440 background on, 79 BPTB, 354–361, 373–380 computer-assisted navigation for, 186–, costs of, 79, 80 CQFT for, 106–108 double-bundle, 82, 147–152 double-bundle, double-stranded hamstring autografts, 155–159 economics of, 81t endobuttons in, 218–224 failed, 496 femoral tunnel placement in, 140–145 fracture complications of, 598–603 gait analysis in, 615–622 graft remodeling, 408–412 graft tensioning in, 392–396 hamstring harvest technique for, 91–94, 95–100 with high tibial osteotomy, 493–499 IntraFix, 351 ligamentization, 408–412

634

Anterior cruciate ligament (ACL) (Continued ) with meniscal allograft transplantation, 493–499 meniscus tears, 486–492 with microfracture, 493–499 mid-third patella tendon graft harvesting for, 101–105 Milagro, 381–384 mini-arthrotomy technique, 364–372 with osteochondral allograft transplantation, 493–499 osteoporosis after, 572–574 partial tears, 470–475 patient expectations, 493 physeal-sparing, 465 postoperative, 514 proprioception and, 535–539 purpose of, 79 radiographs of, 71f restoration of motion, 493 retrodrill technique, 134–137 retroscrew fixation, 299–302 revisions, 443 semitendinosus tendon graft, 110–113 in skeletally immature patients, 457–468 stability results after, 540–548 success rates, 493, 494 surgeon factors, 493 tension after, 327 third-party payor payments, 80 tissue-engineering, 82 transepiphyseal, 462 transphyseal, 467 tunnel widening after, 576–578 vascular complications, 585–588 whipstitch-post tibial fixation, 310–315 rehabilitation principles, 509–520 stability conservative, 521–526 strain during rehabilitation, 501–506 weight bearing and tibia external loading, 13 tear rates, 29t, 35 female to male, 38, 39 prevention programs, 40 risks, 39 Anterior knee problems, 598, allografts, 610 causes of, 612 central quadriceps tendon, 610 graft-related, 607–610 pain, 609 procedure-related, 611 reducing, 612 rehabilitation, 612 Anterior laxity, high-stiffness, slippage-resistant cortical fixation, 204 Anterior shear force knee flexion angle and, 13 at tibia, 13 Anterior-posterior translation control, 9 Anterolateral rotatory instability (AMRI), 429, 432, 433 Anteromedial (AM) bundle, 3, 12, 147, 153, 155, 168, 621 anatomy of, 4, 473 arthroscopic view of, 5, 8 crossing patterns, 7, 176 arthroscopic view of, 8 femoral guide, 175 femoral insertion points, 6 footprints, 172 insertion landmarks, 174 sockets for, 150

Index Anteromedial (AM) bundle (Continued ) tibial tunnels, 174 Anteromedial portal, 129–131 advantages of, 129 possible complications of, 131 technique, 129 Anteromedial rotatory instability (AMRI), 429 Anteromedial tibial drill guide, 158 Anteroposterior (AP) instability, 71 Anteroposterior (AP) laxity, 53 Antibiotic administration, 554 AP instability. See Anteroposterior instability AP laxity. See Anteroposterior laxity Aperture fixation, 547 Approximate Entropy, 619, 619 Arterial complications, 585 Arthrex, 262f, 299 Arthro-Care Coblation device, 172 Arthrofibrosis, 509 Arthroplasty, 499 Arthroscopy, 188 in Stryker Biosteon Cross-Pin System, 268 Arthrosis, following reconstruction, 71 studies on, 72 Arthrotek, 233 Autogenous patellar tendon grafts, 364–372 button fixation, 370 closure contralateral graft, 371 ipsilateral graft, 370 graft harvest, 369 contralateral, 369 ipsilateral, 369 lateral incisions in, 366 preoperative planning, 364 radiographs, 364 rehabilitation, 364 surgical management, 436 technique, 365, 371 arthroscopic evaluation, 365 exposure, 365 femoral exposure, 366 femoral tunnel, 369 graft fixation, 369 graft passage, 369 graft tensioning, 369 medial arthrotomy, 366 notchplasty, 367 postoperative care, 371 preparation, 365 tibial exposure, 365 tibial tunnel, 367 tunnel placement, 367–368 Autografts BPTB, 278 BTB, numbness saphenous nerve and, 580 double-bundle, double-stranded hamstring, 155–159 surgical procedure, 155–159 hamstring, 246, 547, 607 double-bundle, double-stranded, 155–159 numbness saphenous nerve and, 580 methods, 84 patellar tendon, 607 in revisions, 447 semitendinosus, tripled or quadrupled, 305–308 stability, 548 strength comparisons, 84

Autografts (Continued ) in tunnel widening, 577 Autologous chondrocyte implantation, 493–499 Autologous hamstring grafts, 427–440 failure analysis, 427 concomitant pathology, 429 radiographic evaluation, 428, 428f graft fixation, 440 graft selection, 440 hardware management, 432 removal, 433, 435 tunnel management, 434–440 classification of positions, 435 enlargement, 439 malplacement, 434 surgical, 436

B Bacterial infections, 557 Basic fibroblast growth factor (bFGF), 565 Beath pin, 175, 280 Betadine, 365 Beta-tricalcium phosphate copolymers, 382 bFGF. See Basic fibroblast growth factor Bicycling, 505, 524 Bioabsorbable materials, in tibial fixation, 216 Biofeedback, 568 Biofilm formation, 552 Biological scaffolds, 424 Biomechanics, 7 in surgery, 9 BioScrew XtraLok applying tension with, 329 tibial fixation, 328–329 results, 328 in tibial tunnel, 328 troubleshooting, 329 BMD. See Bone mineral density BMPs. See Bone morphogenetic proteins Bone dowel CT scan of, 322 harvesters, 318, 321 tibial fixation, 316–322 compacting, 318 harvesting, 316 surgical technique, 316–319 tendon-tunnel healing, 318–319 tunnel widening, 320 Bone mineral density (BMD), 194, 195, 200, 204 decreased, 600 in interference screw fixation, 361 osteoporosis and, 572 schematic, 573f, 574 Bone morphogenetic proteins (BMPs), 423, 627 Bone Mulch Screw, 595 Bone plugs, 103, 308 tibial, 360 Bone proteins, 423 Bone wedge technique, 292, 293 chisel for, 294 Bone-patellar tendon-bone (BPTB), 80, 84, 194, 567 allograft, autograft, 278 endobutton continuous loop, 373–380 fixation, 195 fixation options, 449t

635

Index Bone-patellar tendon-bone (BPTB) (Continued ) graft strengths, 86 hamstring v., 525 in tunnel widening, 576 harvesting, 603 interference screw fixation in, 354–361 BMD in, 361 bone blocks in, 358 bone tunnel preparation in, 356 divergence, 359 graft preparation, 354 graft protectors in, 355 graft-tunnel mismatch, 360 parallelism, 359 pin position in, 358 screw and graft position in, 357 screw selection, 354 tibial pin in, 356 roof impingement in, 123 stability rates, 548 strain, 506 suture configuration, 355f Bone-tendon-bone (BTB), 195, 397 autograft, numbness saphenous nerve and, 580 endobutton continuous loop, 373–380 areas of, 376 femoral tunnel, 375 graft length, 374f, 375 measuring, 376 results, 380 revision surgery, 377 technique in detail, 374 technique overview, 373 troubleshooting, 380 Xtendobuttons in, 378 interference screw fixation, 197f intratunnel fixation of, 199 femoral fixation, 199 tibial fixation, 199 Borelli, 7 Bovine flexor tendon, double spike plate and, 324 BPTB. See Bone-patellar tendon-bone Bracing in ACL deficiency, 64 environmental risk factors and, 18 functional, 82 postoperative, 82 strain and, 506 BTB. See Bone-tendon-bone Bucket-handle tears, 489, 489–490 Bungee cord effect, 284

C Calcanei, Candida glabrata, 557 C-arm, 463 Cartilage restorative procedures, 499 Cast immobilization, 481 CDC. See Centers for Disease Control and Prevention Cell therapy, 424 experimental protocol, 629 healing with, 629 Centers for Disease Control and Prevention (CDC), 557 Central quadriceps free tendon (CQFT) for ACL reconstruction, 106–108 technique, 106

636

Central quadriceps free tendon (CQFT) (Continued ) troubleshooting, 107 bottom view of, 108 with PLLA screw, 109 reconstructions exposure, 107f fixation of, 108 release of, 107 sizing of, 108 CG. See Control groups Chemical treatments, 562 Cincinnati Knee Rating System, 538 Closed kinetic chain squatting exercises, Clostridium, 557, 557 Cold compression device, 371 Cold machines, 82 Collagen crimp, 411 remodeling, 413 Computed tomography (CT) scan, 592 angiography, 594 of bone dowel, 322 sagittal, 594 tibial fracture, 604 Computer-assisted navigation, 186–192, postoperative screenshots, 191 precision and, 186–192, rationale for, 186 results of, 191 techniques, 187 Concomitant meniscal surgery, 611 Contamination, 552, 563 Continuous passive motion (CPM), 82, 282, 466, 483, 513, 593 Contralateral graft, 518 closure, 371 harvest, 369 postoperative rehabilitation, 512 special considerations, 372 Control groups (CG), 48 Corin anchor, 448 Coring reamers, 214 Coronal image inversion recovery, 58 T1 weighted, 58 Cortical screw post femoral fixation, 227–232 biomechanics, 227 ease of, 232 equipment for, 232 EZLoc, 234 fixating single strands, 230 history, 227 morbidity in, 232 radiographs, 231 stability of, 232 surgical technique, 228–231 femoral post, 228–230 incision, 228 insertion screw, 228 materials, 228 universal salvage, 232 uses of, 231 Cosmesis, 99–100 Counter bores, 317, 319 CPM. See Continuous passive motion CQFT. See Central quadriceps free tendon C-reactive protein (CRP), 553, 553, 569 Crossing pattern, 6

Index Crossing pattern (Continued ) AM and PL bundles, 7 arthroscopic view of, 8 Cross-pin guide frame, 281 hardware complications, 587, 589 CRP. See C-reactive protein Crutches, 511 Cryo/Cuff, 511, 513, 514, 515 CT scan. See Computed tomography Cushing retractors, 367 Cyclical loading, 523 lower extremity, 524 Cyclops lesion, 569, 569f, 570, 612

D Data conversions, 32 DaVinci, Leonardo, 7 DBST technique. See Double-bundle, single-tendon technique Deep vein thrombosis (DVT), 596 Deficiency, 63 bracing in, 64 hamstrings in, 63 natural history of, 70 quadriceps in, 63 rehabilitation, 64 Differential Variable Reluctance Transducer (DVRT), 501–502 limitations of, 502 schematic drawing of, 502f Direct fixation, 285 indirect fixation v., 311 Disposables, 81 DLET. See Doubled lateral extensor of toes Donor age, 562 Double spike plate (DSP), 324–327 basic concept, 324 biomechanical data, 324 graft fixation steps, 325 impactor tip, 325 under optional tension, 325f pullout graft fixation with, 326 radiographs of, 326 rationale for, 324 specifications, 324 three-bundle graft fixation with, 326 troubleshooting, 327 two-bundle graft fixation with, 326 Double-bundle, single-tendon (DBST) technique, 161 anatomy in, 161 preliminary results of, 163, 165 scientific rationale for, 162 special considerations in, 165 surgical technique, 162–163 trouble shooting in, 166 Doubled lateral extensor of toes (DLET), 421 Drains, 516 DSP. See Double spike plate DVRT. See Differential Variable Reluctance Transducer DVT. See Deep vein thrombosis Dynamic functional joint stability, 615

E EGF. See Epidermal growth factor Egypt, 3 Electrical stimulation, 568 Electron microscopy, 532

Elliptical trainers, 519, 524 Endobuttons, 109, 463, 585 CL length, 220, 224 continuous loop BTB fixation system, 373–380 areas of, 376 femoral tunnel, 375 graft length, 374f, 375 measuring, 376 results, 380 revision surgery, 377 technique in detail, 374 troubleshooting, 380 Xtendobuttons in, 378 femoral fixation, 218–224 biomechanics of, 218 clinical results of, 218 passing sutures, 224 pulling out, 224 surgical technique, 219–222 troubleshooting, 222–224 flattening, 222–224 graft construct, 220 hardware complications, 585 lateral cortex blowout and, placement of, 465 retrograde tension and, 223 seating, 221 sutures, 475 Xtendobutton and, 225 EndoPearl, 287, 293 MRI, 295 Enterobacter, 554 Enterococcus faecalis, 558 Environmental risk factors, 18 bracing and, 18 Epidermal growth factor (EGF), 423, 626 Erysipelothrix rhusiopathiae, 554 Erythrocyte sedimentation rate (ESR), 553, 569 Escherichia coli, 558 ESR. See Erythrocyte sedimentation rate EUA. See Examination under anesthesia Examination under anesthesia (EUA), 56 Exercise, 60 Exposures, 28, 32 Extension torque, 504 Extension-flexion motion, 505 Extensor, deficit, 61f, 62 EZLoc, 209 as cortical femoral fixation device, 234 fixation properties of, 235 growth plates and, 239 pa, 235 radiographs of, 235 removal of, 240 on soft tissue grafts, 233–241 design, 233 diameter, 233 femoral cortex and, 239 mechanism, 233 packaging, 233 revision surgery with, 239 in skeletally immature patients, 238 troubleshooting, 240 surgical technique, 236–238 hamstring allograft preparation, 236 tibia allograft preparation, 236 tibial fixation, 238

637

Index

F Fastlok device staple positioning, 307 for tibial fixation, 305–308 graft fixation, 306 results, 306 scientific rationale for, 305 surgical technique for, 306 troubleshooting, 308 tunnel preparations, 306 Females, ACL tear rates in, 38, 39 Femoral blocks, 81 Femoral condyle lesions, 495f Femoral cortex blown out, 224 EZLoc and drilling through, 239 Femoral fixation endobutton ACL reconstruction, 218–224 biomechanics of, 218 clinical results of, 218 flattening, 222–224 passing sutures, 224 principle of, 219 pulling out, 224 surgical technique, 219–222 troubleshooting, 222–224 EZLoc, on soft tissue grafts, 233–241 graft sleeve and tapered screw, 333 interference screw, 287–292 options, 450t Pinn-ACL crosspin system, 253–259 cortical length measurement in, 255 cross-pin implant selection, 255 femoral tunnel in, 255 graft fixation, 257 graft harvesting, 254 graft passing, 256 implant design, 253 notchplasty, 254 surgical technique, 254–257 tibial tunnel in, 255 Rigidfix device for, 277–282 cruciform periosteal incision, 279 graft positioning, 280 graft preparation, 279 postsurgical care, 282 skin incision, 278f surgical technique, 278 troubleshooting, 282 Stratis ST, 242–249, 250 advantages and disadvantages of, 250 aperture fixation, 244 arthroscopic preparation, 246 design rationale of, 243 femoral tunnel and, 244 femoral tunnel in, 246 graft block, 244f graft block insertion, 248 graft integrity and, 244 graft limb orientation, 245 graft preparation, 246 graft-block-graft construct, 248 implant removal, 250 pullout strength, 244 system, 244, 245 technique, 245–249

638

Femoral fixation (Continued ) tendon harvest, 245 tibial tunnel in, 246 transverse tunnel, 247 Stryker Biosteon Cross-Pin, 267–274 femoral tunnel location, 270 graft harvest, 270 potential pitfalls, 275 tibial tunnel location, 270 TransFix, 261–266 biomechanics, 261 clinical results, 261 surgical technique, 262 troubleshooting, 265 X-ray demonstrating, 358 Femoral guide, 136 Femoral post endobutton tied to, 230 endobutton-CL fabric loop passed around, 228 fabric tape tied around, 229 whipstitch technique, 229 Femoral reamer, 237 Femoral tunnel, 140–145 ACL isometry and, 141 anterior edge notching, 291 arthroscopic view of, 127 in autogenous patellar tendon grafts, 369 channel length, 220 creation of, 149 divergence, 438 double, 145 drilling, 237, 240 formation, 219–222, 247 basic technique, 219 endobutton seating, 221 endobutton-CL length, 220 finishing, 219 graft construct, 220 graft passing, 221 notchplasty, 219 passing suture removal, 222 principles of, 219 redrilling, 219 tunnel length, 219 functional anatomy and, 140 graft harness in, 257 graft sleeve and tapered screw, 333 guidance, 191 incorrect, 437, 438 IntraFix, 344 Isometric graft attachment sites, 143 length of, 237 measuring, 237, 246, 334 pin placement for, 357 in Pinn-ACL crosspin system, 255 placement, 135, 621 preparation of, 156 rasps for smoothing, 357 reuse of, 437 Stratis ST and, 244 in Stratis ST femoral fixation, 246 Stryker Biosteon Cross-Pin System, 270 transition line between graft attachments, 143 transverse, 243 Femur AM and PL bundle insertion points at, 6 exposure, 366

Index Femur (Continued ) fixation devices on, 205f footprints, 172 fracture, 598 tibia and, 188 Fiber attachment length changes, 142 Fiberstick Suture, 299 Fixation implants, 80 breakage, 231 Fixation pin advanced, 250 loaded, 250 Flexion angles, 132 ACL loading and, 14 anterior shear force and, 13 Flexor, deficit, 61f, 62 Flexwire, 271–272 Fluoroscopic control, 131 Football, 34 Australian rules, 39 Foreign body reaction, 89, 90, 563 4ST technique, 115–119, 313 with bone block, 119 without bone block, 119 Fracture complications, 598–603 femur, 598 patella, 601 tibial, 603 plateau, 603 tubercle, 603 Fraudulent tissue procurement, 563 Freezing, 562 Friction, 310 Full extension, 523 Full flexion, 523

G Gait analysis, 615–622 advanced theoretical considerations, 619–620 modified complexity hypothesis model, 620 biomechanical research on, 617 tibial rotation, 617 future work on, 620–621 double bundle, 620 tunnel positioning, 621 Gait training, 525 Galen, Claudius, 3 Galileo, 7 Gastrocnemius, 92, 524 Gene therapy, 423 healing and, 628 Glides, 568 GM-CSF. See Granulocyte-macrophage colony-stimulating factor Gore-Tex, 88, 592 ligament failure, 89f tunnel enlargement after, 90 Gracilis, 96f, 465 arthroscopic appearance of, 337 colored sutures on, 345, 346 graft, 93 in graft sleeve, 334 in hamstring harvesting, 116 harvesting, 232 identifying, 97 Graft malpositioning, 566 Graft remodeling, 408–412

Graft sleeve and tapered screw, 330–340 advantages of, 332 application of, 333 basic science, 329–330 biomechanical testing, 330 biocompatibility and histology of fixation site healing, 331, 332 femoral fixation, 333 femoral tunnel, 333 future of, 340 gracilis in, 334 graft passage, 334 hamstring tendon graft preparation, 333 postoperative management, 335 follow-up, 335 rehabilitation, 335 problems with, 337 radiographs, 338 rehabilitation protocol, 339 results, 338 surgical technique, 332–335 tibial fixation, 335, 336 supplemental, 337 tibial tunnel, 333 with tibialis allografts, 335 Graft tensioning, 392–396, 399–404, 567 basic science, 400 biomechanical studies on, 392 clinical relevance, 395 high and low initial tension, 394 relaxation of, 393 tension-flexion curve, 392 devices, 404 factors effecting, 400f high-tension, 402 histology, 400 knee fixation angle, 404 low-tension, 402 physiological, 401 preconditioning, 403 pretensioning, 403 randomized trials, 396 specific, 401 strategies, 404 stress relaxation, 403 in vivo studies, 395 essential tension effects, 395 initial tension in, 395 Graft Tunnel Solution (GTS) System, 202 Graft-block-graft construct, 248, 249 Graftmaster, 220 Grafts. See Autografts; specific types Graft-tunnel mismatch, 360 Gram stain, 553 Granulocyte-macrophage colony-stimulating factor (GM-CSF), 70 Growth factors, 423, 625–629 Growth plates, EZLoc and, 239 GTS System, 331f. See Graft Tunnel Solution System

H Hall Effect Strain Transducer (HEST), 501 Hamstring, 60, 417 in ACL deficiency, 63 allograft, surgical preparation, 236 anti-shear vector of, 64

639

Index Hamstring (Continued ) autografts, 246, 547 double-bundle, double-stranded, 155–159 numbness saphenous nerve and, 580 BPTB v., 525 in tunnel widening, 576 co-contractions, 15 femoral graft fixation options, 450t four bundle graft, 329f grafts, 115–119 advantages and disadvantages of, 116 double-bundle compatibility, 117 fifth limb in, 118f gracilis, 116 lengths of, 115 parameters for, 115–117 postoperative rehabilitation protocol, 339 strength of, 86, 116 tibial fixation in, 116, 211–216 troubleshooting, 118 harvest technique, 91, 95, 245 anatomy, 95 clinical experience, 100 complications, 94 cosmesis in, 100 graft preparation, 93, 98 in large patients, 100 oblique anteromedial incision for, 92f premature amputation in, 99 problems with, 99 saphenous nerve trauma, 99–100 skin incision, 91 surgical, 96 tendon exposure, 91 tendon freeing, 98 tendon identification in, 99 tendon release, 92 tendon stripping, 92, 98, 99 timing of, 98 interference screw fixation, 284–295 biological boundary conditions, 285 biomechanical considerations, 284–285 boundary considerations, 284 graft preparation, 287 technical considerations, 287–295 quadrupled tendon graft, 277 regeneration, 528–533 animal models, 531 functional studies, 530 future directions, 533 gross morphology, 530 histological studies, 531 radiographic studies, 528 universality, 530 in soccer, 61 strengthening, 524 tendon graft, 161–166 autologous, 427–440 preparation, 333 Handball, 39 Hardware complications, 585–590 cross-pin fixation, 587, 589 endobuttons, 585 interference complications, 585 skeletally immature patients, 588 tibial fixation, 588

640

Healing ACL, 477 biocompatibility and histology of, 331, 332 cell-based therapy, 629 early graft, 408 gene therapy, 628 graft tunnel, 417–424 animal studies, 418–420 biological scaffolds, 424 bone proteins in, 423 cell therapy in, 424 future directions in, 422 gene therapy in, 423 growth factors in, 423 human studies, 417 MMP inhibitors, 424 growth factors and, 625–629 intraarticular healing and, 626–627 intraarticular, 626 intraosseous, 627 lateral-side structures, 479 ligamentization phase, 412 ligaments, 477–479 MCL, 479 PCL, 478 proliferation phase of, 409 promoting, 318–319 revascularization during, 410 at six weeks, 410f Hemarthrosis, 55, 371 Hemostats, 107 Heparin, 593 HEST. See Hall Effect Strain Transducer High tibial osteotomy, 493–499 High-stiffness, slippage-resistant cortical fixation, 204–209 advantages of, 208 examples of, 205 preferred technique, 208 in restoring anterior laxity, 204 stiffness principle in, 207 High-tension grafts, 402 Hips, control, 65 History, ligament tears acute, 54 chronic, 54 HIV. See Human immunodeficiency virus HLA types, 565 Hooke, 7 Hormonal risk factors, 20 concerns and, 23 laxity and, 20 ligament biology and, 23 monthly distribution of injuries and, 20 Human immunodeficiency virus (HIV), Human studies, graft tunnel healing, 417 Humani Corporis Fabrica Libris Septum (Vesalius), 3 Hybrid fixation, 290 femoral, 292, 441 possibilities for, 294 tibial, 295, 441 Hybrid grafts, 152 Hydroxyapatite, 268 osteoconductive properties of, 269 Hyperextension, 510f, 511 avoiding, 523

Index

I IAT. See Intraarticular graft tension IG. See Intervention groups IKDC scoring system, 137, 176, 262, 461, 488, 593 mean scores, 453 normal classifications, 159, 445 IL. See Interleukin Iliotibial band, 465 grafts, 466 Immunological response, 563 Indirect fixation, direct fixation v., 311 Infections, 551–558 allografts and, 557 bacterial, 557 viral, 557 causes of, 563 development times, 553 diagnosis of, 553–554 clinical findings, 553 imaging studies, 554 laboratory findings, 553 microbiology, 554 intraoperative graft contamination, 558 management protocol, 554–556 antibiotic administration, 554 microbiology of, 554 morbidity and, 562 pathogenesis, 551–552 biofilm formation, 552 contamination, 552 local factors, 552 systemic factors, 551 prevalence, 551 sterilization and, 563 surgical management, 555 debridement, 555 graft removal, 555 graft retention, 555 irrigation, 555 persistent cases, 554 persistent septic arthritis, 556 postoperative, 555 tissue-handling and, 563 Infrapatellar contracture syndrome, 568 Infrared camera, 188f Initial tension, 396 effects of, 394 increasing, 393f tension-flexion curve, 392 in vivo studies, 395 Insall-Salvati ratio, Insertion site, anatomy, 4 Intercondylar notch, measuring, 367 Interference screw fixation, 197f biodegradable, 286, 382f, 386–390, 441 biomechanical, 387–388 clinical results, 388–389 fixation strength, 387 Inion Hexalon, 387f, 389 MRI, 389, 390 randomized trials, 388 strength retention, 388 torsional strength, 388 BPTB, 354–361 BMD in, 361 bone blocks in, 358

Interference screw fixation (Continued ) bone tunnel preparation in, 356 divergence, 359 graft preparation, 354 graft protectors in, 355 graft-tunnel mismatch, 360 parallelism, 359 pin position in, 358 screw and graft position in, 357 screw selection, 354 tibial pin in, 356 cross-pin fixation, 215 development of, 285 different types of, 286 dilation of site, 290 divergence of, 198 femoral, 287–292 graft rotation in, 292 hybrid fixation, 292 screw insertion problems, 292 hamstring tendon, 284–295 biological boundary conditions, 285 biomechanical considerations, 284–285 boundary considerations, 284 graft preparation, 287 technical considerations, 287–295 hardware complications, 585 intratunnel fixation with, 205, 207 metal, 198 rigid interosseous compression and, 215 tibial, 294–295 hybrid fixation, 295, 297 intratunnel view, 295 screw diameter, 295 screw insertion, 295 tunnel preparation, 294 tunnel widening and, 578 Interleukin (IL), 408 Intervention groups (IG), 48 Intraarticular femoral screws, 586f Intraarticular graft tension (IAT), 206 Intraarticular healing, 626 Intraarticular replacements, 460–461 IntraFix, 204, 215, 282, 341–351 with allografts, 343 closure, 350 design of, 341 histology in, 342 MRI of, 342f postoperative dressings, 350 postoperative management, 351 results, 351 screw insertion, 349 sheath insertion, 348 sizing scheme for, 342f, 350 surgical technique, 342–350 device insertion, 344 femoral tunnel, 344 graft fixation, 344 graft passage, 344 graft preparation, 342 graft tensioning, 344 tibial fixation, 344 tibial tunnel, 343 troubleshooting, 347–350 failure to advance, 350 low bone density, 350

641

Index IntraFix (Continued ) screw breakage, 349 sheath overinsertion, 347 short grafts, 350 Intraoperative graft contamination, 558 Intraosseous healing, 627 Intratunnel ACL graft fixation alternative, 201 biomechanics of, 194–202 limitations of studies on, 195 BMD in, 196 bone-tendon-bone, 199 femoral fixation, 199 tibial fixation, 199 BPTB fixation in, 196 with interference screw, 205, 207 soft tissue, 199 Ipsilateral graft, postoperative rehabilitation, 512 Isokinetic torques, 537 Isometric graft attachment sites, 143

K K. pneumoniae, 558 K wire, 132 Kelly clamps, 212 Kennedy ligament augmentation device, 88 Kinematic analysis, 10 Kirschner wires, 149, 150, 188, 213 trackers attached with, 189 Klebsiella, 554 Knee extension, 510 emphasis of, 516 Knee fixation angle, 404 Knee flexion, 510, 602 regaining, 511 Knee instability, 445 Knee stability symmetry, 540 Knee stability Test-Pre, 190 Kocher clamp, 221 KT-1000 tests, 13, 274, 402, 454, 512 in ligament tear physical exams, 55 KT-2000, 152

L Lachman test, 54 in ligament tear physical exam, 55 Lacrosse, 34 LAD. See Ligament augmentation device Landing activity, 616f Large patients, 100 Lateral capsule repair, 483 tear, 482 Lateral collateral ligament (LCL), 42, 477–483 clinical examination of, 479 imaging, 480 postoperative rehabilitation, 483 treatment principles, 481–483 Lateral cortex, 223 blowout with endobutton fixation, Lateral femoral condyle (LFC), 4, –, , 180, 473 Lateral-side structures healing, 479 repair, 482 Law of functional adaptation, 407

642

LCL. See Lateral collateral ligament Leeds-Keio graft, 88 Less invasive fracture fixation (LISS), 603 LFC. See Lateral femoral condyle Ligament augmentation device (LAD), 88 Ligament restraints, static, 24 Ligament tears acute, 53 history, 54 chronic, 53 history, 54 partial, 53 physical exam, 54 EUA, 56 hemarthrosis, 55 KT-1000 tests, 55 Lachman test, 54, 55 locking, 55 MRI, 56 patellofemoral injury, 55 pivot shift, 54 radiographs, 56 valgus laxity, 55 Ligamentization, 84, 399–400 phase, 412 Ligastic graft, 88 LISS. See Less invasive fracture fixation Lizard tail phenomenon, 528 Load to failure (LTF), 84, 195, 201, 211, 341 data, 85t tests, 422 Longitudinal graft, 285 Longitudinal studies, 536, 538 Loop, 310 Low-stiffness cortical fixation, 205, 206 Low-tension grafts, 402 LTF. See Load to failure Lysholm score, 61

M Magnetic resonance imaging (MRI), 9, 14, 54, 70, 121, 179, 471 angiography, 595 biodegradable interference screw fixation, 389, 390 EndoPearl, 295 follow-up, 300f of IntraFix, 342f knee, 569 in ligament tears, 56 neotendons, 531 of patellar tendon shortening, 608 of PCL, 478f of semitendinosus regeneration, 529, 529 Males, ACL tear rates, 38, 39 Marcaine, 268, 568 Matrix metalloproteinases (MMPs), 424 MCL. See Medial collateral ligament Medial collateral ligament (MCL), 12, 15, 42, , 274, 429, 477–483 clinical examination of, 479 healing, 479 imaging, 480 postoperative rehabilitation, 483 treatment principles, 481–483 Meniscal allograft implantation (MAT), 495 Meniscus tears, 486–492 lateral, 487 superior surface of, 487

Index Meniscus tears (Continued ) leaving in situ, 487 medial, 488 inferior surface of, 488 repairing, 488 3 months after, 491 ACL surgery and, unstable, 489 Menstrual cycle, 20f Mersilene-Fastlok, 307 Micro particle dispersion (MPD), 383 Microfracture, 493–499 Mid-third patella tendon graft harvesting for, 101–105 exposure, 101 fashioning, 104 skin incision in, 101, 102, 102f taking, 101 length of, tubularizing, Milagro, 381–384 basic science of, 382 biochemical data, 381 biomechanical data, 381 clinical information, 383 pearls, 384 postimplantation, 383 uses of, 383 Mini-arthrotomy technique, 364–372 Mitrek Intra-Fix sheath, 273 Mitrogenic growth disturbance, 459 MMPs. See Matrix metalloproteinases Morphine, 568 MPD. See Micro particle dispersion MRI. See Magnetic resonance imaging Muscle contraction, dynamic, 24 Muscular inhibition, 522

N Navigation, 82 Neovascularization, 411 Nerve branch distribution, 587–588 in infrapatellar region, 589 Neuromuscular function tests, 535 Neuromuscular risk factors, 23 Neuromuscular training comprehensive, 48 strengthening, 46 technique, 46 varied, 47 Neurovascular injury, 480, 595 Neurovascular safe zone, 263 Newton, Isaac, 7 Nitinol wire, 265 Non-anatomical fixation, 284 Nonaperture fixation, 547 Noncontact injuries, 12–15 occurrence of, 12–13 Notch length, 191 Notch width anatomical risk factors and, 19 studies evaluating, 21 measuring, 180f PCL impingement and, 123, 124 Notchplasty, 179–182 anatomy in, 179

Notchplasty (Continued ) arthroscopic view of, 183 in autogenous patellar tendon grafts, 367 complications, 182 indications, 180 initiation of, 184 Pinn-ACL crosspin system and, 254 potential risks, 180 techniques, 182 bony, 183 debridement in, 183 Numbness saphenous nerve, 580–582 anatomical investigations, 581 BTB autografts, 580 clinical examination, 581 hamstring autografts, 580

O OATS. See Osteochondral autograft transfer system OCAl. See Osteochondral allograft Orthopilot, 187–188 Orthotape-Fastlok, 307 Osteoarthritis, 443–444 pathophysiology of, 69 tibial rotation and, 619 Osteochondral allograft (OCAl), 496 Osteochondral autograft transfer system (OATS), 496 Osteoporosis, 572–574 bone loss and, 573 defining, 573 musculoskeletal injuries and, 573 peak bone mass and, 572 surgery and, 573 as risk factor, 574 Osteotomes, 102, 104 Outpatient surgery, 513 Overexertion, 518

P P. aeruginosa, 558 Partial tears, 470–475 complications, 475 preoperative considerations, 470–472 history, 470 imaging, 471 indications, 472 physical examination, 471 rehabilitation, 475 results, 475 surgical technique, 472–473 anesthesia, 472 diagnostic arthroscopy, 472 graft preparation, 473 positioning, 472 reconstruction technique, 473 surgical landmarks, 472 Passive extension, 511 Passive movement test, 535 Patella fracture, 601 Patellar tendon graft, 277, 417 autografts, 607 measurement of, 608f, 609 Patellofemoral injury, 55 Patient information screens, 189 Patient Specific Functional Scale, 538

643

Index PCL. See Posterior cruciate ligament PDGF. See Platelet-derived growth factor PDS, 354 PE. See Pulmonary embolism Peak posterior ground reaction forces, 14 PEP Program, 48–49 Peptostaphylococcus, 554 Periosteum, 312, 366 Peroneus allograft, 313 Pes anserinus, 212 PGA. See Polyglycolic acid Phantom foot mechanism, 24 Physeal injury, basic science research on, 459 Physeal-sparing reconstructions, 465 postoperative rehabilitations, 466 Physical exam in anatomical double-bundle reconstruction, 169 ligament tears, 54 ACL v. PCL, 54 EUA, 56 KT-1000 tests, 55 Lachman test, 54, 55 locking, 55 MRI, 56 patellofemoral injury, 55 pivot shift, 54 radiographs, 56 valgus laxity, 55 partial tears, 471 Physical therapy, 82, 516, 538 home v. clinic, 525 in tibial fixation for hamstring grafts, 216 timing strengthening, 523 Pinn-ACL crosspin system femoral fixation, graft fixation, 257 for femoral fixation, 253–259 cortical length measurement in, 255 cross-pin implant selection, 255 femoral tunnel in, 255 graft harvesting, 254 graft passing, 256 implant design, 253 notchplasty, 254 surgical technique, 254–257 tibial tunnel in, 255 tibial fixation, 257 tips and tricks for, 257 troubleshooting, 259 video technique, 259 PL bundle. See Posterolateral bundle PLA pin, 215 Platelet-derived growth factor (PDGF), 423, 565, 626 PLGA. See Polylactide co-glycolide PLLA screw. See Poly-L-lactic acid screw PLRI. See Posterolateral rotatory instability PMN cells. See Polymorphonuclear cells PMRI. See Posteromedial rotatory instability POL. See Posterior oblique ligament Polyester tape, 306f Polyglycolic acid (PGA), , 386 Polylactide co-glycolide (PLGA), 383 Poly-L-lactic acid (PLLA) screw, 109, 355–356, 383, 386 Polymers, combining, 386–390 Polymorphonuclear (PMN) cells, 553 Porcine tibiae, double spike plate and, 324

644

Posterior cruciate ligament (PCL), 42, 157, 213, 279, 429, 477–483, 567 clinical examination of, 479 combined injury, 477–483 healing, 478 imaging, 480 impingement, 121–127 complications, 121 definitions, 121 diagnosis, 121 preventing, 123 principle for avoiding, 124 surgical technique for avoiding, 125 knee injury, 480 ligament tears, ACL tears v., 54 MRI of, 478f postoperative rehabilitation, 483 treatment principles, 481–483 Posterior horn avulsion tear, 487f Posterior oblique ligament (POL), 429 Posterolateral (PL) bundle, 3, 147, 155, 164, 621 anatomy of, 4 arthroscopic view of, 5, 8 crossing patterns, 7, 176 arthroscopic view of, 8 femoral insertion points, 6 footprints, 172 graft, 175 guidewire insertion for, 151 insertion landmarks, 174 sockets for, 150 tibial insertion, 6 tibial tunnels, 174 Posterolateral femoral drill guide, 157 Posterolateral rotatory instability (PLRI), 429, 431, 432 Posterolateral tibial drill guide, 158 Posteromedial rotatory instability (PMRI), 429, 432 Post-screw construct, 164 Preconditioning, 403 Pretensioning, 403 Prevention studies, 43 functioning of, 50 individual v. population-based, 50 intervention timing, 49 performance effects of, 50 program specifics, 49 results of, 44 education, 44 isolated proprioceptive training, 46 isolated strengthening and conditioning, 44 neuromuscular training, 46–48 summary of, 45 Proliferation phase, 409 Propionibacteriaceae, 554 Proprioception, 525, 535–539 comparing, 537t defining, 535 evaluating, 536 training exercises, 535 Proximal tunnel revision surgery and, 231 wall blowout, 231 Pseudomonas aeruginosa, 554 Pulmonary embolism (PE), 596 Purse-strings, 338

Index

Q Q angle, anatomical risk factors and, 19 Q-400 tests, 13 Quadriceps, 13, 60 in ACL deficiency, 63 central tendon, 610 strengthening, 524 tendon allograft, 313 tendon graft strength, 85

R Radiation sterilization, 562 Radiographs, 489 of ACL reconstruction, 71f in anatomical double-bundle grafts, 165 anteroposterior, 121, 444, 461f, 462 of autologous hamstring grafts, 428, 428f cortical screw post femoral fixation, 231 of distal left femur, 599 of DSP, 326 EZLoc, 235 graft sleeve and tapered screw, 338 of hamstring regeneration, 528 lateral, 181, 439, 461f, 462 ligament tear, 56 posteroanterior weight-bearing, 429, 430 post-revision, 447f stress, 430 tibial fracture, 604, 605 of transverse fractures, 602 of two-stage revision, 234f Radiolucency, 312 Reconstructions additive costs, 80 all-inside, 300f anatomical double-bundle, 144, 147–152, 168–177 anesthesia and positioning, 170 clinical results, 152, 154, 177 complications, 176 diagnostic examination, 171 graft fashioning in, 150 graft placement in, 151 graft preparation, 170 graft tensioning and fixation, 152 history in, 169 hybrid grafts in, 152 imaging, 169 indications in, 169 landmarks in, 170 physical examination in, 169 postoperative considerations, 175–176 preoperative considerations, 169 preparation for, 147 procedure, 147–152 results, 176 specific steps, 171 surgical technique, 170–171 tibial tunnels in, 147 anatomical double-bundle, double-stranded hamstring autografts, 155–159 arthroscopic reconstruction, 156 femoral tunnels in, 156 graft fixation in, 157 graft harvesting, 155 graft positioning in, 157

Reconstructions (Continued ) graft tensioning in, 157 postoperative care, 159 setup, 155 surgical procedure, 155–159 tibial tunnels in, 157 anatomical double-bundle with semitendinosus hamstring tendon graft, 161–166 anatomy in, 161 applications of, 165 checking grafts in, 164 preliminary results of, 163 radiographs in, 165 scientific rationale for, 162 special considerations in, 165 surgical technique, 162–163 troubleshooting, 166 anatomical single-bundle, 144 anterior knee problems after, 607–612 arthroscopic, 111 arthrosis following, 71 studies on, 72 with autologous chondrocyte implantation, 493–499 autologous hamstring tendon, 427–440 background on, 79 BPTB, 354–361 computer-assisted navigation, 186–, accuracy without, 186 postoperative screenshots, 191 precision in, 186 rationale for, 186 techniques, 187 costs of, 79 additive, 80 information on, 79 institutional fixed, 80 postoperative, 81 CQFT for, 106–108 exposure, 107f fixation of, 108 technique, 106 troubleshooting, 107 double-bundle, 82 double-bundle, double-stranded hamstring autografts, 155–159 economics of, 81t endobuttons in, 218–224 failed, 496 femoral tunnel placement in, 140–145 fracture complications of, 598–603 gait analysis in, 615–622 graft remodeling, 408–412 graft tensioning in, 392–396 hamstring harvest technique for, 91, 95 anatomy, 95 clinical experience, 100 complications, 94 cosmesis in, 100 graft preparation, 93, 98 in large patients, 100 premature amputation in, 99 problems with, 99 saphenous nerve trauma, 99–100 skin incision, 91 surgical, 96 tendon exposure, 91 tendon identification in, 99 tendon release, 92

645

Index Reconstructions (Continued ) tendon stripping, 98, 99 timing of, 98 with high tibial osteotomy, 493–499 IntraFix, 351 ligamentization, 408–412 with meniscal allograft transplantation, 493–499 meniscus tears, 486–492 with microfracture, 493–499 mid-third patella tendon graft, 101–105 exposure, 101 fashioning, 104 skin incision in, 101, 102, 102f taking, 101 Milagro, 381–384 mini-arthrotomy technique, 364–372 with osteochondral allograft transplantation, 493–499 osteoporosis after, 572–574 partial tears, 470–475 complications, 475 preoperative considerations, 470–472 rehabilitation, 475 results, 475 surgical technique, 472–473 patient expectations, 493 physeal-sparing, 465 postoperative rehabilitations, 466 postoperative, 514 proprioception and, 535–539 purpose of, 79 radiographs of, 71f restoration of motion, 493 retrodrill technique, 134–137 preliminary results, 137 surgical, 136 retroscrew fixation, 299–302 revisions, 443 allograft, 447 apertural fixation, 448 autograft, 447 cortical fixation, 448 failure, 444, 453f knee instability, 445 literature on, 454 postoperative, 451 surgical procedure, 446 treatment options, 444 two-stage, 453 semitendinosus tendon graft, 110–113 in skeletally immature patients, 457–468 stability results after, 540–548 success rates, 493 surgeon factors, 493 tension after, 327 third-party payor payments, 80 tissue-engineering, 82 transepiphyseal, 462, 463–464 postoperative rehabilitation, 464 surgical technique, 463 transphyseal, 467 rehabilitation, 468 tunnel widening after, 576–578 vascular complications, 585–588 whipstitch-post tibial fixation, 310–315 Reflex sympathetic dystrophy (RSD), 568 Rehabilitation in ACL deficiency, 64

646

Rehabilitation (Continued ) aggressive v. conservative, 577 allograft, 525 anatomical double-bundle, 175 anterior knee problems, 612 graft sleeve and tapered screw, 335, 339 hamstring graft, 339 LCL, 483 MCL, 483 partial tears, 475 PCL, 483 physeal-sparing reconstructions, 466 postoperative, 451 contralateral graft, 512 early, 514 ipsilateral graft, 512 operative considerations, 513 outpatient surgery, 513 phase II, 517 phase III, 518 phase IV, 519 premises of, 521 preoperative planning for, 364, 510 mental preparation for, 512 principles of, 509–520 protocol, 521 returning to competition after, stability-conservative, 521–526 abductor strengthening, 524 adductor strengthening, 524 cyclical loading in, 523, 524 equipment, 525 in first three months, 522 fixation point healing, 522 full extension in, 523 full flexion in, 523 gait training, 525 gastrocnemius in, 524 graft strength, 522 hamstring strengthening, 524 history of, 521 home v. clinic therapy, 525 hyperextension in, 523 muscular inhibition after, 522 proprioception, 525 quadriceps strengthening, 524 results, 526 stairs in, 524 strength testing, 526 symmetric stability after, 522 timing strengthening, 523 triceps surae, 524 stiffness, 568 strain during, 501–506 imaging techniques, 502–503 measuring, 501 rank comparison of, 504 studies on, 503 transepiphyseal reconstruction, 464 transphyseal reconstruction, 468 RER. See Retroeminence ridge Resident’s ridge, 180, 182 Retrodrill technique, 134–137 assembly, 135 pin in, 135 preliminary results, 137 surgical, 136

Index Retrodrill technique (Continued ) traditional method, 135 Retroeminence ridge (RER), 157 Retroscrew fixation, 299–302 insertion of, 299 operative technique, 299, 302 placement, 303 tibial, 187–192, 300 Revascularization, 410 Revision screwdrivers, 435 Revisions, 443 allograft, 447 apertural fixation, 448 autograft, 447 cortical fixation, 448 failure, 444, 453f knee instability, 445 literature on, 454 radiographs after, 447f surgical procedure, 446 stage I, 446 stage II, 446 treatment options, 444 tunnel widening and, 578 interference screw fixation and, 578 noninterference screw fixation and, 578 two-stage, 453 RICE, 568 Rigid fix device, 216 absorbable pins, 281 drill holes, 281 for femoral sided fixation, 277–282 cruciform periosteal incision, 279 graft positioning, 280 graft preparation, 279 postsurgical care, 282 skin incision, 278f surgical technique for, 278 troubleshooting, 282 Rigid interosseous compression, in tibial fixation, 215 Risk factors anatomical, 19 notch width of, 19, 21 Q angle and, 19 environmental, 18 bracing and, 18 hormonal, 20 concerns and, 23 laxity and, 20 ligament biology and, 23 monthly distribution of injuries and, 20 neuromuscular, 23 Rome, 3 Roof impingement, 121–127, 236 in BPTB graft, 123 complications, 122 definition, 122 diagnosis, 122 principle for avoiding, 124 surgical technique for avoiding, 125 Rotational stability, 9 Roux, Wilhelm, 399 RSD. See Reflex sympathetic dystrophy Rugby, 34 Running, 524

S Sagittal CT, 594 Sagittal graft, 285 Sagittal proton density image, 58 Saphenous nerve infrapatellar branch of, 611 trauma, 99–100 Sartorius fascia, 212 Secondary sexual characteristics, 459 Self-tapping, cancellous compression screws, 317 Semimembranosus, 528, 533 Semitendinosus, 96f, 465, 528, 533, 537 in anterior incision, 97 autograft, tripled or quadrupled, 305–308 colored sutures on, 345, 346 double-bundle graft, preparation, 162 finding, 96 graft, 93 hamstring tendon graft, 161–166 harvesting, 97, 212, 232 insertion, 96 isolation of, 97 MRI of, 529 tendon graft, 110–113 clinical results of, 112 complications, 113 diagram of, 112 preparation for, 111 quadrupled, 111, 112 surgical technique, 111–113 tripled, 111 Sensory disturbance, 581f Septic arthritis, 556 Shuttle machine, 515 Side-to-side difference (SSD), 540 Single-socket, double-bundle graft, 302 final inspection of, 303 preparation, 303 Single-socket, single-bundle graft, 299 Skeletally immature patients, 457–468 accessing, 458 complications in, 588 EZLoc in, 238 mitrogenic growth disturbance in, 459 natural history, 457 normal growth and development, 458 physeal injury, 459 recommendations, 461 treatment options, 460, 461 Soccer, 32, 70 hamstrings and, 61 indoor, 34 Soft tissue grafts, 199 EZLoc femoral fixation on, 233–241 design, 233 diameter, 233 mechanism, 233 packaging, 233 fixing, 238 tibial fixation bone dowel, 316–322 intratunnel, 330–340 WasherLoc, 316–322 Sports.See also specific sports tear rates in, 32

647

Index SSD. See Side-to-side difference Stability allograft, 548 aperture fixation, 547 autograft, 548 BPTB, 548 by graft subgroups, 547 by graft types, 547 nonaperture fixation, 547 results, 540–548 symmetrical stability, 540 statistical methods, 540 study criteria of, 540 divided by graft and function, Stair climbing, 505 Stair-stepping machine, 519 Standing extension, 511 Standing habit, 516 Staphylococcus aureus, 554, 557, 558 Staphylococcus caprae, 554 Staphylococcus epidermidis, 554 Static tensioners, 213 Stationary bike, 519 Sterilization, 563 Stiffness, 565–570 etiology of, 565–568 genetic predisposition for, 565 infrapatellar contracture syndrome, 568 surgical factors, 566 principle, 207 rehabilitation, 568 treatment, 569 Straight leg raise exercises, 515 Strain BPTB, 506 bracing and, 506 imaging techniques, 502–503 measuring, 501 rank comparison of, 504 studies on, 503 weight bearing and tibia external loading, 13 Stratis ST, femoral fixation, 242–249, 250 advantages and disadvantages of, 250 aperture fixation, 244 arthroscopic preparation, 246 design rationale of, 243 femoral tunnel and, 244 femoral tunnel in, 246 graft block, 244f graft block insertion, 248 graft integrity and, 244 graft limb orientation, 245 graft preparation, 246 graft-block-graft construct, 248 implant removal, 250 pullout strength, 244 system, 244, 245 technique, 245–249 tendon harvest, 245 tibial tunnel in, 246 transverse tunnel, 247 Stress relaxation, 403 Stride-to-stride variability, 618 Stryker Biosteon Cross-Pin System biomechanical performance of, 274 bony healing, 269 elasticity of, 269

648

Stryker Biosteon Cross-Pin System (Continued ) femoral fixation, 267–270, 274 femoral tunnel location, 270 graft harvest, 270 potential pitfalls, 275 results, 274 tibial tunnel location, 270 postoperative care, 273 surgical technique, 268–273 initial arthroscopy, 268 tibial fixation, 270 Styker Dracon graft, 88 Surgery, 626 biomechanics considerations in, 9 Sutures, 220, 221 BPTB, 355f on gracilis, 345, 346 passing, 224 pulling, 468 removing, 222 on semitendinosus, 345, 346 tangled, 223–224 tibial hybrid fixation using, 297 Synovial fluid infiltration, 577 Synthetic bone substitute, 439, 440 Synthetic grafts failure of, 88 future of, 89 history of, 88 types of, 88

T Tanner stages, 458, 459, 462 Tears prevention programs, 40 rates, 29t, 35 female to male, 38, 39 risks, in sports, 32 Tendo-Achilles allograft, 313 Tensile strength testing, 532 Tension-flexion curve, biomechanical studies on, 392 Tensioning pattern, 6 TGFs. See Transforming growth factors Threaded cannulated drill pins, 135f, 137, 138 Threaded femoral cancellous screw and washer, 230f 3D kinematics, 24 3ST/2Gr technique, 115–119, 313 five strand, 118 morbidity, 118 results, 118 surgical technique, 118 uses, 118 Tibia, 5 allograft, surgical preparation, 236 allografts at, 208 anterior shear force at, 13 eminence avulsion, exposure, 365 femur and, 188 footprints, 172 fracture, 603 CT, 604 plateau, 603 radiographs, 604, 605 tubercle, 603

Index Tibia (Continued ) insertion landmarks, 174 lateral capsule tear, 482 PL bundle insertion point at, 6 proximal, 454f Tibial fixation, , 158, 384 backup, 296 BioScrew XtraLok, 328–329 results, 328 in tibial tunnel, 328 troubleshooting, 329 cancellous bone and, 320 devices, 205f EZLoc, 238 Fastlok device for, 305–308 graft fixation, 306 results, 306 scientific rationale for, 305 surgical technique for, 306 troubleshooting, 308 tunnel preparations, 306 graft sleeve and tapered screw, 335 for hamstring grafts, 211–216 bioabsorbable materials in, 216 bone grafting, 214 cross-pin, 215 distal tunnel fixation in, 214 graft cycling, 212 graft preparation in, 211 limited debridement in, 214 modified physical therapy after, 216 pretension, 212 rigid interosseous compression in, 215 tibial tunnel length in, 213 hardware complications, 588 interference screw, 294–295 IntraFix, 344 in intratunnel graft fixation, 199 options, 452t Pinn-ACL crosspin system, 257 retroscrew, 288–300, 301 screws for, 441 soft tissue graft bone dowel, 316–322 intratunnel, 330–340 WasherLoc, 316–322 Stryker Biosteon Cross-Pin System, 273 tension after, 327 tension during, 324, 326 whipstitch-post, 310–315 bioabsorbable screws, 312 biomechanics of, 310–311 clinical results, 311 direct v. indirect fixation, 311 ease of, 315 elongation, 310 graft sizing, 314 graft techniques, 313 metallic screws, 315 morbidity, 315 principle behind, 311 radiolucency, 312 screw insertion, 314 screw tightening, 314 short graft, 315 stability, 315 stiffness, 310

Tibial fixation (Continued ) surgical technique, 311–314 sutures, 311 tensioning, 313 tibial screws, 311 trimming tendon grafts, 314 troubleshooting, 315 tying, 314 unicortical screw placement, 315 X-ray demonstrating, 358 Tibial guide 65-degree Howell, 126 placement of, 189 validation of, 126 Tibial pin, 356 Tibial rotation, 617 osteoarthritis and, 619 Tibial tubercle, 162 Tibial tunnel, 137, 163, 264 AM, 174 in anatomical double-bundle ACL reconstruction, 147 arthroscopic view of, 127, 343 in autogenous patellar tendon grafts, 367 BioScrew XtraLok in, 328 bone dowel harvesting from, 316 bone grafting of, 214 debridement of articular edge of, 214 dilating, 317 distal fixation, 214 graft sleeve and tapered screw, 333 guidance, 191, 279 IntraFix, 343 maximizing length of, 213 outlets, 149 in Pinn-ACL crosspin system, 255 PL, 174 placement for, 125, 236, 367, 368 straight-line, 368 preparation of, 157 screw diameter and, 295 in Stratis ST femoral fixation, 246 Stryker Biosteon Cross-Pin System, 270 walls in, 368 whipstitches in, 212f Tibialis allograft, 313 graft sleeve with, 335 preparation of, 340 Tilts, 568 Tissue-handling, 563 TMC. See Trimethylene carbonate TNF. See Tumor necrosis factor Transepiphyseal reconstruction, 462 surgical technique, 463–464 TransFix, 417, 433 Arthrex, 262f, 299 femoral fixation, 261–266 biomechanics, 261 clinical results, 261 surgical technique, 262 troubleshooting, 265 tunnel hook, 264 Transforming growth factors (TGFs), 423, 565, 626, 627 Transphyseal reconstruction, 467 postoperative rehabilitation, 468 Transtibial technique, 122, 124 Transverse cannula, 256

649

Index Transverse drill, 251 guide, 271 Transverse fractures, 602 Tray rentals, 81 Trevira ligament, 88 Triceps surae, 524 Trimethylene carbonate (TMC), 386 Tumor necrosis factor (TNF), 408, 565 Tunnel widening, 576–578 adverse effects, 578 direct, 578 revision surgery and, 578 decreasing, 578 factors associated with, 576–577 aggressive v. conservative rehabilitation, 577 allograft v. autograft, 577 fixation location, 577 hamstring v. BPTB, 576 synovial fluid infiltration, 577 by graft and fixation type, 577f, 578 methods of, 576 identifying, 576 literature analysis, 576 Tunnels. See specific types Two bundle grafts, 302 2ST/2Gr technique, 115–119, 229, 313 graft preparation optimal length, 117 sizing, 117 whipstitch implantation, 117

U Uterine T clamp, 107

V Valgus, laxity, 55 Valgus movements, 24 Vascular complications, 585–588 arterial, 585 defects, 595 venous, 596 Vascular endothelial growth factor (VEGF), 565, 625, 626 VEGF. See Vascular endothelial growth factor Venous complications, 596 Vesalius, Andreas, 3 Viral disease, 557 Volleyball, 34

W WasherLoc, 206, 208, 215, 593 orientation of, 317 schematic of, 317 slippage resistance, 320 tibial fixation, 316–322

650

WasherLoc (Continued ) impacting, 317 self-tapping, cancellous compression screws, 317 surgical technique, 316–319 tendon-tunnel healing, 318–319 WBC. See White blood cell Weighted means, 33 Whipstitch implantation, 227, 310 direct v. indirect fixation, 311 femoral post, 229 first, 117 second, 117 placement, 312 post-tibial fixation, 310–315 bioabsorbable screws, 312 biomechanics of, 310–311 clinical results, 311 ease of, 315 elongation, 310 graft sizing, 314 graft techniques, 313 metallic screws, 315 morbidity, 315 principle behind, 311 radiolucency, 312 screw insertion, 314 screw tightening, 314 short graft, 315 stability, 315 stiffness, 310 surgical technique, 311–314 sutures, 311 tensioning, 313 tibial screws, 311 trimming tendon grafts, 314 troubleshooting, 315 tubularization, 312 tying, 314 unicortical screw placement, 315 in tibial tunnel, 212f White blood cell (WBC), 553 WHO. See World Health Organization Wire navigators, 147, 148 navi-tip of, 149 World Health Organization (WHO), 573 Wrestling, 34

X Xtendobutton, 219, 224, 380 in continuous loop BTB fixation systems, 378 endobuttons and, 225 in revision cases, 225

Y Yardsticks, 515