Research into Spinal Deformities (Studies in Health Technology and Informatics, 91)

RESEARCH INTO SPINAL DEFORMITIES 4

Studies in Health Technology and Informatics Editors Jens Pihlkjaer Christensen (EC, Luxembourg); Arie Hasman (The Netherlands): Larry Hunter (USA): Ilias Iakovidis (EC, Belgium); Zoi Kolitsi (Greece): Olivier Le Dour (EC, Belgium); Antonio Pedotti (Italy); Otto Rienhoff (Germany): Francis H. Roger France (Belgium); Niels Rossing (Denmark); Niilo Saranummi (Finland): Elliot R. Siegel (USA): Petra Wilson (EC, Belgium)

Volume 91 Earlier published in this series Vol. 63. R. Rogers and J. Reardon. Recommendations for International Action Vol. 64. M. Nerlich and R. Kretschmer (Eds.), The Impact of Telemedicine on Health Care Management Vol. 65. J. Manas and A. Gasman (Eds.), Textbook in Health Informatics Vol. 66. The ISHTAR Consortium (Eds.), Implementing Secure Healthcare Telematics Applications in Europe Vol. 67. J Oates and H. Bjerregaard Jensen (Eds.). Building Regional Health Care Networks in Europe Vol. 68. P. Kokol, B. Zupan. J. Stare, M. Premik and R. Engelbrecht (Eds.). Medical Informatics Europe '99 Vol. 69. F.-A. Allaert. B. Blobel. C.P. Louwerse and E.B. Barber (Eds.). Security Standards for Healthcare Information Systems Vol. 70. J.D. Westwood. H.M. Hoffman. G.T. Mogel. R.A. Robb and D Stredney (Eds.). Medicine Meets Virtual Reality 2000 Vol. 71. J.T. Ottesen and M. Danielsen (Eds.), Mathematical Modelling in Medicine Vol. 72. I. Iakovidis, S. Maglavera and A. Trakatellis (Eds.), User Acceptance of Health Telematics Applications Vol. 73. W. Sermeus, N. Kearney. J. Kinnunen, L. Goossens and M. Miller (Eds.). WISECARE Vol. 74. O. Rienhoff. C. Laske, P. van Eecke, P. Wenzlaff and U. Piccolo (Eds.), A Legal Framework for Security in European Health Care Telematics Vol. 75. G.O. Klein (Ed.). Case Studies of Security Problems and their Solutions Vol. 76. E.A. Balas. S.A. Boren and G D. Brown (Eds.). Information Technology Strategies from the United States and (he European Union Vol. 77. A. Gasman. B. Blobel. J. Dudeck. R. Engelbrecht. G. Gell and H. -U. Prokosch (Eds.). Medical Infobahn for Europe Vol. 78. T. Paiva and T. Penzel (Eds.), European Neurological Network Vol. 79. A. Marsh. L. Grandinetti and T. Kauranne (Eds.). Advanced Infrastructures for Future Healthcare Vol. 80. R.G. Bushko, Future of Health Technology Vol. 81. J.D. Westwood. H.M. Hoffman. G.T. Mogel, D. Stredney and R.A Robb (Eds.). Medicine Meets Virtual Reality 2001 Vol. 82. Z. Kolitsi (Ed.). Towards a European Framework for Education and Training in Medical Physics and Biomedical Engineering Vol. 83. B. Heller. M. Löffler, M. Musen and M. Stefanelli (Eds.), Computer-Based Support for Clinical Guidelines and Protocols Vol. 84 V L. Patel. R. Rogers and R. Haux (Eds.). MEDINFO 2001 Vol. 85. J.D. Westwood. H.M. Miller Hoffman. R.A. Robb and D. Stredney (Eds.). Medicine Meets Virtual Reality 02/10 Vol. 86. F. H. Roger-France, I. Mertens. M.-C. Closon and J. Hofdijk (Eds.). Case Mix: Global Views. Local Actions Vol. 87 F. Mennerat (Ed.). Electronic Health Records and Communication for Better Health Care Vol. 88 A. Tanguy and B. Peuchot (Eds.). Research into Spinal Deformities 3 Vol. 89 B. Blobel, Analysis. Design and Implementation for Secure and Interoperable Distributed Health Information Systems Vol. 90 Gy. Surján. R. Engelbrecht and P. McNair (Eds.). Health Data in the Information Society ISSN: 0926-9630

Research into Spinal Deformities 4 Edited by

Theodoros B. Grivas Orthopaedic Department, "Thriasio" General Hospital, Magula, Greece

IOS Press

Ohmsha

Amsterdam • Berlin • Oxford • Tokyo • Washington, DC

© 2002, The authors mentioned in the Table of Contents All rights reserved. No pan of this book may be reproduced, stored in a retrieval system, or transmitted. in any form or by any means, without prior written permission from the publisher. ISBN I 58603 289 5 (IOS Press) ISBN 4 274 90552 7 C3047 (Ohmsha) Library of Congress Control Number: 2002113598

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Preface On the 24-27 May 2002, the International Research Society of Spinal Deformities (IRSSD) held its fourth biannual scientific meeting at the Astir Palace Resort. Vouliagmenis, in Athens, by the beautiful and serene setting of the Aegean Sea. The extended essays of the papers and posters presented at the meeting are included in this book unmodified. Presentations where the authors failed to submit the extended texts have not been included. The scientific seeds planted at the previous meetings of the IRSSD gave this 4th Meeting a wide variety and a rich collection of 132 papers on research and related clinical practice, which were presented by delegates from 23 countries, from all the continents. Information about the history of the IRSSD. the previous forms of the society and its transformation, which led to the foundation of the IRSSD in Pescara in 1994 can be found in the previous books of "Research into Spinal Deformities, Volume 1-3". and will not be repeated here. The meeting comprised 17 Scientific Sessions on Spinal Deformities: Aetiology. Incidence. Natural History and Prognosis. Genetics and Growth. Anatomy, Pathology and Basic Science. Assessment, Biomechanics, Gait, Surface Topography, Imaging, Morphological Aspects (3-D) of Spinal Deformity. Technology, Cervical Spine, Spondylolisthesis - Low Back Pain. Conservative Treatment - (Physiotherapy - Brace), Surgical Treatment and Outcome. The programme was completed with three keynote lectures, the presidential address and three round table discussions. Particular emphasis was given to the scientific programme, in order to have a well-balanced amount of research and clinical papers on Spinal Deformities. The scope of this policy was not only to disseminate the latest trends of research in spinal deformities to the clinical environment, but also for researchers to have analogous input from the problems of recent clinical practice, so that the consequent interaction could be productive in a collegial, international atmosphere, with approximately 200 registered delegates. The objectives of the Society, to fuse together different trends of research in spine deformities, was thus fulfilled during the meeting, as Prof. Sevastik also highlighted in a previous meeting of the IRSSD. As chairman of the 2002 Athens meeting I wish to express sincere thanks to the members of the International Scientific Committee: Mark Asher (USA), Carl-Eric Aubin (Canada), Alexandros Chatzipavlos (Greece), Peter Dangerfield (England). Panagiotis Korovesis (Greece). Hubert Labelle (Canada), Morey Moreland (USA), George Sapkas (Greece). John Sevastik (Sweden), Panagiotis Soucacos (Greece). Ian Stokes (USA), Nobumasa Suzuki (Japan), Dirk Uyttendaele (Belgium), who during their busy schedule took the time to evaluate the number of abstracts that were submitted. To our great satisfaction this meeting exceeded our common expectations. This

was indeed very satisfying, as more colleagues are starting to take an interest in the research field of spinal deformities. I would like to thank the President of the IRSSD, Professor Nobumasa Suzuki, for raising the sum of $10,000, in order to contribute to the meeting. Also the sponsoring companies, Biomet Merck Hellas, Depuy Medec, Ebedent, Iamex, Mathys Medical, Medical Plus, Ortholand, Plus Endoprothetic Hellas, Unimed, who supported this meeting with their generous contributions. The Congress Organisers and Secretariat "Aktina - City Congress SA" for their faultless organization at the meeting, and last but not least, I would like to thank all the participants, without whom the Meeting would not have been possible. I hope that all participants found this meeting rewarding. Athens, May 2002 Dr. Theodoros B. GRIVAS, MD

Table 1. Statistical data relating to the delegates No. 1 2 3

4 5 6 7 8 9

10 12 13

14 15 16 17

18 19 20 21 22 23

Total

Country Australia Belgium Brazil Canada Switzerland Chile Czech Republic Germany France United Kingdom Greece Italy Israel Ireland Japan Malaysia The Netherlands Poland Russia Sweden Saudi Arabia Turkey United States Delegates Nurses Accompanying Persons Exhibitors

No. of Delegates

4 6 1 14 2 2 1 3 13 11

71 10 3 2 11 3 3 12 2

2 1 2 22

153 20 19 35

Contents Preface, T.B. Grivas The Effects of Exposure to Intense, 24 h Light on the Development of Scoliosis in Young Chickens, F. Nette, K. Dolynchuck, X. Wang, A. Daniel, C. Demianczuk, M. Moreau, J. Raso, J. Mahood and K. Bagnall Is the Labyrinthine Dysfunction a Causative Factor in Idiopathic Scoliosis? G. Kapetanos, M. Potoupnis, A. Dangilas, K. Markou and J. Pournaras Is the Central Nervous System a Causative Factor in Idiopathic Scoliosis? M. Potoupnis, G. Kapetanos, V.K. Kimiskidis and P.P. Symeonides The NOTOM Hypothesis for Idiopathic Scoliosis: Is it Nullified by the Delayed Puberty of Female Rhythmic Gymnasts and Ballet Dancers with Scoliosis? R. G. Burwell and P.M. Dangerfield Etiologic Theories of Idiopathic Scoliosis: Neurodevelopmental Concepts to be Evaluated, R. G. Burwell and P.H. Dangerfield Study of the Rib Cage Deformity in Children with 10°-20° of Cobb Angle Late Onset Idiopathic Scoliosis, using Rib-Vertebra Angles — Aetiologic Implications, T.B. Grivas, P. Samelis, T. Chadziargiropoulos and B.D. Polyzois Lateral Spinal Profile in School-screening Referrals with and without Late Onset Idiopathic Scoliosis 10°-20°, T.B. Grivas, S. Dangas, P. Samelis, C. Maziotou and K. Kandris Etiologic Theories of Idiopathic Scoliosis: The Apical Spinal Deformity — Relevance to Surgical Practice, R.G. Burwell, R.K. Pratt and J.K. Webb Etiology of the So-called "Idiopathic Scoliosis". Biomechanical Explanation of Spine Deformity. Two Groups of Development of Scoliosis. New Rehabilitation Treatment; Possibility of Prophylactics, T. Karski Comparison of Body Weight and Height Between Normal and Scoliotic Children, T.B. Grivas, A. Arvaniti, C. Maziotou, M. Manesioti and A. Fergadi Evolution of 3D Deformities in Adolescents with Progressive Idiopathic Scoliosis, I. Villemure, C.-É. Aubin, G. Grimard, J. Dansereau and H. Labelle Adolescent Idiopathic Scoliosis: Natural History and Prognosis, C.J. Goldberg, D.P. Moore, E.E. Fogarty and F.E. Dowling Prediction of Spinal Deformity in Scoliosis from Geometric Torsion, P. Poncet, J.L. Jaremko, J. Ronsky, J. Harder, J. Dansereau, H. Labelle and R.F. Zernicke The Natural History of Early Onset Scoliosis, C.J. Goldberg, D.P. Moore, E.E. Fogarty and F.E. Dowling The Incidence of Idiopathic Scoliosis in Greece — Analysis of Domestic School Screening Programs, T.B. Grivas, K. Koukos, U.I. Koukou, C. Maziotou and B.D. Polyzois School Screening in the Heavily Industrialized Area — Is There Any Role of Industrial Environmental Factors in Idiopathic Scoliosis Prevalence? T.B. Grivas, P. Samelis, B.D. Polyzois, B. Giourelis and D. Polyzois Biomechanical Factors Affecting Progression of Structural Scoliotic Curves of the Spine, S. Lupparelli, E. Pola, L. Pitta, O. Mazza, V. De Santis and L. Aulisa Positional Cloning Strategies for Idiopathic Scoliosis, S. Bashiardes, R. Veile, C.A. Wise, L. Szappanos and M. Lovett

1 1 10 12 15 20 25 32 37 47 54 59 64 68 71 76 81 86

Prediction of Curve Progression in Idiopathic Scoliosis from Gene Polymorphic Analysis, M. Inane, S. Minami. Y. Nakata, M. Takaso. Y. Otsuka, H. Kitahara, K. Isobe, T. Kotani, T. Marina and H. Moriya Mechanical Modulation of Vertebral and Tibial Growth: Diurnal versus Full-time Loading. I.A Stokes, J. Gwadera, A. Dimock and D.A. Aronsson Growth Patterns in Patients with Unoperated Congenital Vertebral Anomaly. C.J. Goldberg, D.P. Moore. E.E. Fogarty and F.E. Dowling Morphometric Characteristics of the Thoracic and Lumbar Pedicles in the Greek Population. A. Christodoulou, T. Apostolou and I. Terzidis Does Coralline Hydroxyapatite Conduct Fusion in Instrumented Posterior Spine Fusion? P. Korovessis, M. Repanti and G. Koureas The Effects of Mechanical Loading on the mRNA Expression of Growth Plate Cells. I. Villemure, M.A. Chung, C.S. Seek, M.H. Kimm, J.R. Matyas and N.A. Duncan Back Shape Assessment in Each of Three Positions in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS): Evaluation of a 10-Level Scoliometer Method Interpolated to 18-Levels. R.G. Bunvell, R.K. Aujla, A.A. Cole, A.S. Kirby. R.K. Pratt. J.K. Webb and A. Moulton The Validity of Clinical Examination in Adolescent Spinal Deformities. C. Grosso. S. Negrini, A. Boniolo and A.Æ. Negrini New Approach to Objective Diagnostics of Polyfunctional Disorders of the Neuromuscular Regulation in Children with Various Forms of Spine Deformities. G.P. Dmitrieva, M.Y. Karganov. N.N. Khlebnikova, O.I. Kovaleva, M.I. Kozhevnikova. S.B. Landa and L.A. Noskin Spinal Mobility and EMG Activity in Idiopathic Scoliosis through Dynamic Lateral Bending Tests, O.C. Ciolofan. C.-É. Aubin. P.A. Mathieu, M. Beauséjour. V. Feipel and H. Labelle Three Dimensional Analysis of Chest Wall Motion during Breathing in Healthy Individuals and Patients with Scoliosis using an Ultrasonography-based System. T. Kotani, S. Minami, K. Takahashi. K. Isobe, Y. Nakata, M. Takaso. M. Inoue, S. Nishikawa, T. Maruta, T. Tamaki and H. Moriya Relation Between the Pelvis and the Sagittal Profile in Adolescent Idiopathic Scoliosis: The Influence of Curve Type. M. Charlebois, J.-M. Mac-Thiong, M.-P. Huot. J.A. De Guise, W. Skalli and H. Labelle Study of Patient Positioning on a Dynamic Frame for Scoliosis Surgery. K. Duke. J. Dansereau, H. Labelle, A. Koller, J. Joncas and C.-É. Aubin Joint Segmental Kinematic Trunk Motion and C.O.P. Patterns for Multifactorial Posturographic Analysis. M. D'Amico and P. Roncoletta Transverse Plane Pelvic Rotation Measurement, B. Lucas, M. Asher. T. Mclff, D. Lark and D. Burton Baropodographic Measurements and Averaging in Locomotion and Postural Analysis. M. D'Amico and P. Roncoletta Movement Analysis of Scoliotic Subjects using Fastrak, A. Rahmatalla, N. Chokalingam, P. Dangerfiehl. E.-N. Ahmed, T Cochrane. J Dove and N.Maffulli Motion Segment Stiffness Measured without Physiological Levels of Axial Compressive Preload Underestimates the in vivo Values in All Six Degrees of Freedom, M.G. Gardner-Morse, I.A. Stokes, D. Churchill and G. Badger Kinematic Differences in Lower Limb Gait Analysis of Scoliotic Subjects, N. Chokalingam. A. Rahmatalla. P. Dangerfield. T. Cochrane, E-N. Ahmed and J. Dove Assessing Changes in Three Dimensional Scoliotic Deformities with Difference Maps. D.L. Hill. D.C. Berg. T. Church and V J Raso

90 97 101 104 109 1 14

119 123

126

130

135

140 144 149 153 156

162 167

1 73 178

Three-dimensional Shape Analysis of the Scoliotic Spine using MR Tomography and Rasterstereography, E. Hierholzer and L. Hackenberg The Effect of Posture on Quantec Measurements, A.M. Macdonald, C.J. Griffiths, F.J. McArdle and M.J. Gibson Local Energy as a Measure of Back Symmetry in Scoliosis, N.G. Durdle, T. Soonawalla, V.J. Raso and D.L. Hill Monitoring the Thoracic Sagittal Curvature in Kyphoseoliosis with Surface Topography: A Trend Analysis of 57 Patients, F.J. McArdle, C.J. Griffiths, A.M. Macdonald and M.J. Gibson Use of Functional Tests to Increase the Efficiency of Scoliosis Screening Diagnosis by COMOT Method, V.N. Sarnadsky, N.G. Fomichev and M.V. Mikhailovsky Cotrel-Dubousset Instrumentation (CDI) in the Treatment of Congenital Spinal Deformities. Computer Topography Evalution, M.V. Mikhailovsky, V.N. Sarnadsky and A.L. Khanaev Three-dimensional Correction with CD Instrumentation and Harrington Rod in the Treatment of Idiopathic Scoliosis, M.V. Mikhailovsky, V.V. Novikov and V.N. Sarnadsky Motion Analysis of the Trunk and Spine. Surface Measurement using Computer Optical Topography, V.N. Sarnadsky, S.Y. Vilberger and N.G. Fomichev Development of the Neurocentral Junction as seen on Magnetic Resonance Images, T. Rajwani, R. Bhargava, R. Lambert, M. Moreau, J. Mahood, V.J. Raso, H. Jiang, EM. Huang, X. Wang, A. Daniel and KM. Bagnall The Components of the Magnetic Resonance Image of the Neurocentral Junction, T. Rajwani, EM. Hilang, C. Secretan, R. Bhargava, R. Lambert, M. Moreau, J. Mahood, V.J. Raso and KM. Bagnall Accuracy of Rasterstereography versus Radiography in Idiopathic Scoliosis after Anterior Correction and Fusion, L. Hackenberg, E. Hierholzer and U. Liljenqvist Spine-Rib Rotation Differences at the Apex in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS): Evaluation of a Three-level Ultrasound Method, R.G. Burwell, R.K. Aujla, A.A. Cole, A.S. Kirby, R.K. Pratt, J.K. Webb and A. Moulton Sagittal and Transversal Plane Deformity in Thoracic Scoliosis, T. Kotwicki A New X-ray Calibration/Reconstruction System for 3D Clinical Assessment of Spinal Deformities, F. Cheriet, L. Remaki, C. Bellefleur, A. Koller, H. Labelle and J. Dansereau Preliminary Study of a New Real-time Ultrasound Method for Measuring Spinal and Rib Rotation in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS), R.G. Burwell, R.K. Aujla, A.A. Cole, A.S. Kirby, R.K. Pratt, J.K. Webb and A. Moulton Geometric and Postural Analysis of Mild Idiopathic Scoliotic Patients, N. Champain, R. Dupuis, V. Pomero, B. Mouilleseaux, J. Dubousset and W. Skalli Self-calibration of Biplanar Radiographs for a Retrospective Comparative Study of the 3D Correction of Adolescent Idiopathic Scoliosis, J. Novosad, F. Cheriet, S. Delorme, S. Poirier, M. Beauséjour and H. Labelle Semi-automation of the 3D Reconstruction of the Spine using Wavelets and Splines, S. Deschênes, B. Godbout, W. Skalli and J. De Guise 3D Biplanar Statistical Reconstruction of Scoliotic Vertebrae, S. Benameur, M. Mignotte, S. Parent, H. Labelle, W. Skalli and J.A. De Guise 3D Detailed Reconstruction of Vertebrae with Low Dose Digital Stereoradiography, A. Le Bras, S. Laporte, D. Mitton, J.A. De Guise and W. Skalli Pre and Post 3D Modeling of Scoliotic Patients Operated with in situ Contouring Technique, R. Dumas, D. Mitton, J.P. Steib, J.A. De Guise and W. Skalli

\ 84 190 194 199 204 211 216 222 229 235 241

246 251 257

262 267 272 276 281 286 291

3D Reconstruction and Analysis of the Whole Trunk Surface for Non-invasive Follow-up of Scoliotic Deformities, V. Pazos. F. Cheriet, H. Lahelle and J. Dansereau Assessment of the Validity of Observing Three-dimensional Images of the Spine using Polarising, Synchronised Techniques. S. Salvador, X. Wang, M. Moreau, J. Rasa, J. Mahood, R. Currah and K. Bagnall Growth, Development and Puberty Indicators on Spinal Growth. P.H. Dangerfield Scoliosis Study using Finite Element Models, C.-É. Aubin The Role of Muscles and Effects of Load on Growth. I. Stokes and M. Gardner-Morse Achondroplasia: 3D-CT Evaluation of the Cervical Spine, I. Tsitouridis, D. Melidis, M. Iosifidis, A. Morichovitou, F. Goutsaridou. S. Stratilati, G. Giataganas and Ch. Papastergiou Malformations of the Craniocervical Junction: 3D-CT Evaluation, I. Tsitouridis, F. Goutsaridou. A. Morichovitou, G. Giataganas. M. Iosifidis. D. Melidis and S. Stratilati An Experimental Model of Adult-onset Slip Progression in Isthmic Spondylolistesis. A. Patwardhan, A. Ghanayem, J. Simonds. S. Hodges. L. Voronov, O. Paxinos and R. Havey The Significance of Correlation of Radiographic Variables and MOS Short-form Health Survey for Clinical Decision in Symptomatic Low Back Pain Patients. P. Korovessis, A. Dimas and E. Lambiris Sciatic Scoliosis, its Natural History and the Ability of the Mckenzie Management to Influence it. G.P. Spanos Pathomechanic Basics of Conservative Treatment of Progressive Idiopathic Scoliosis according to Dobosiewicz Method based upon Radiologic Evaluation. K. Dobosiewicz. J. Durmala, K. Czernicki, H. Jendrzejek Conservative Management in Patients with Scoliosis — Does it Reduce the Incidence of Surgery? H.-R. Weiss, G. Weiss and H.J. Schaar Influence of Method of Asymmetric Trunk Mobilization on Shaping of a Physiological Thoracic Kyphosis in Children and Youth Suffering from Progressive Idiopathic Scoliosis. K. Dobosiewicz, J. Durmala, H. Jendrzejek and K. Czernicki Curvature Progression in Patients Treated with Scoliosis In-patient Rehabilitation — A Sex and Age Matched Controlled Study. H.-R. Weiss and G. Weiss Exercise Efficiency of Girls with Idiopathic Scoliosis Based on the Ventilatory Anaerobic Threshold. J. Durmala, K. Dobosiewicz. H. Jendrzejek and W. Pius Side Shift Exercise for Idiopathic Scoliosis after Skeletal Maturity. T. Mamyama, T. Kitagawal, K. Takeshita and K. Nakainura Reversal of the Signs and Symptoms of Moderately Severe Idiopathic Scoliosis in Response to Physical Methods. M.C. Hawes and W.J. Brooks Long-term Effects of Scoliosis. M. Asher and D. Burton Quantitative Measurement of Spinal Brace Use and Compliance in the Treatment of Adolescent Idiopathic Scoliosis. G.P. Nicholson. M.W Ferguson-Pell. K. Smith. M. Edgar and T. Morley Is the Boston Brace Mechanically Effective in AIS? V.J. Raso, E. Lou,D.L. Hill. J.K. Mahood and M.J Moreau A Wearable Networked Embedded System for the Treatment of Scoliosis. M. Bazzarelli, N. Durdle, E. Lou. J. Raso and D. Hill Curve Progression and Spinal Growth in Brace Treated Idiopathic Scoliosis. D.J. Wever, K.A. Tonseth and A.G. Veldhuizen Personalized Biomechanical Modeling of Boston Brace Treatment in Idiopathic Scoliosis. D. Périé, C.-É. Aubin. M. Lacroix, Y. Lafon, J Dansereau and H. Labelle Intelligent Brace System for the Treatment of Scoliosis. F. Lou. D. Benfield. J. Raso. D. Hill and N. Durdle

296

300 305 309 314

318

320

322

325 332

336 342

348 352 357 361 365 369

372 378 383 387 393 397

Spine-straight Device for the Treatment of Kyphosis, E. Lou, J. Raso, D. Hill, N. Durdle and M. Moreau Study of Vertebral Morphology in Scheuermann's Kyphosis before and after Treatment, E. Pola, S. Lupparelli, A.G. Aulisa, G. Mastantuoni, O. Mazza and V. De Santis Biomechanics of the Conservative Treatment in Idiopathic Scoliotic Curves in Surgical "Grey Area", L. Aulisa, S. Lupparelli, E. Pola, A.G. Aulisa, G. Mastantuoni and L. Pitta Cell Viability and the Physical Environment in the Scoliotic Intervertebral Disc, S.R.S. Bibby, A. Meir, J.C.T. Fairbank and J.P.G. Urban Brain-stem Dysfunction and Idiopathic Scoliosis, E.K. Dretakis Finite Element Simulation of Various Strategies for CD Correction, V. Lafage, J. Dubousset, F. Lavaste and W. Skalli Idiopathic Scoliosis. Segmental Fusion with Transpedicular Screws, A. Christodoulou, A. Ploumis, C. Zidrou, J. Terzidis and J. Pournaras Spinal Surgery Procedure Discretization, E. Verniest, D. Chopin, A.-P. Godillon-Maquinghen, P. Drazetic, C.-É. Aubin and F.-X. Lepoutre Surgical Treatment of Scoliosis in Myelomeningocele, P. Parisini, T. Greggi, M. Di Silvestre, F. Giardina and G. Bakaloudis Use of a Transpedicular Drill Guide for Pedicle Screw Insertion in the Thoracic Spine, J.-M. Mac-Thiong, H. Labelle, M. Rooze, V. Feipel and C.-É. Aubin Surgical Management of a Congenital Kyphotic Deformity in an Adolescent, A. Christodoulou, A. Ploumis, J. Terzidis, K. Tapsis and P. Hantzidis The Role of Rigid vs. Dynamic Instrumentation for Stabilization of the Degenerative Lumbosacral Spine, P. Korovessis, Z. Papazisis and E. Lambiris Spine Deformity Correlates Better than Trunk Deformity with Idiopathic Scoliosis Patients' Quality of Life Questionnaire Responses, M. Asher, S.M. Lai, D. Burton and B. Manna The Rib Hump after Surgery for Early Onset Spinal Deformity, C.J. Goldberg, D.P. Moore, E.E. Fogarty and F.E. Dowling Trunk Deformity Correction Stability Following Posterior Instrumentation and Arthrodesis for Idiopathic Scoliosis, M. Asher, S.M. Lai, D. Burton and B. Manna Anterior Universal Spine System (USS) for Adolescent Idiopathic Scoliosis (AIS): A Follow-up Study using Scoliometer, Real-time Ultrasound and Radiographs, R.G. Burwell, R.K. Aujla, A.A. Cole, A.S. Kirby, R.K. Pratt, J.K. Webb and A. Moulton Long-term Follow-up of Surgically Treated AIS Patients, D. Hill, V.J. Raso, K. Moreau, M. Moreau and J. Mahood Assessing the Impact of Pelvic Obliquity in Post-operative Neuromuscular Scoliosis, M. Moreau, J. Mahood, K. Moreau, D. Berg, D. Hill and J. Raso Is This as Good as it Gets? It May Be, M. Asher Modification of the Spinal Peak Growth Velocity as a Possible Treatment for Adult Scoliosis, A.G. King Outcomes of Scoliosis Fusion — Is Stiff and Straight Better? M.S. Moreland Author Index

401 405 412 419 422 428 433 438 442 448 454 457 462 465 469

473 477 481 486 489 492 499

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Th.B. Grivus (Ed.) Research into Spinal Deformities 4 IOS Press, 2002

The effects of exposure to intense, 24 h light on the development of scoliosis in young chickens Farrell Nette*, Kim Dolynchuk*, Xiaoping Wang*, Ariadne Daniel*, Christina Demianczuk*, Marc Moreau, James Raso, James Mahood and Keith Bagnall*. Division of Anatomy* and Department of Surgery University of Alberta, Edmonton, Alberta, Canada. T6G 2H7 Tel: 780-492-7094 Fax: 780-492-0462 Email: kbagnall@med ualberta. ca Abstract. The aetiology of adolescent Scoliosis remains unknown and hindering research is the absence of an appropriate animal model. It is now well-established that pinealectomy in young chickens results in the development of scoliosis that has many of the characteristics seen in patients with adolescent idiopathic scoliosis but the mechanism underlying this phenomenon remains elusive. The principle product of the pineal gland is meiatonin and so many studies have focused on studying the effects of reduced levels of this hormone. The results have been mixed and the role of meiatonin remains un~ear. As meiatonin production is inhibited by light, it was hypothesised that providing the chickens with an environment consisting of intense, continuous light would reduce serum meiatonin levels and avoid any of the potential artifacts involved with the pinealectomy surgery. Consequently, pinealectomised and normal chickens were exposed to very intense light for complete 24 h in each day. At the end of 22 days in this environment serum meiatonin levels had been reduced to very low levels in all chickens. Most importantly, 15% of the normal chickens had developed scoliosis and the number of pinealectomised chickens that developed scoliosis increased from 50% to 80%. The results showed that a method for reducing serum meiatonin without pinealectomy has been established and which can be used in further experiments. Furthermore, the results also showed that reduced levels of serum meiatonin has significant effects on the development of scoliosis. The indication is that there is a threshold level of serum meiatonin below which scoliosis may develop probably in conjunction with some other factor which has yet to be identified.

1. Introduction Despite extensive research over the last 100 years [1], the cause of adolescent idiopathic scoliosis (AIS) remains a mystery. In particular, a useful animal model for research purposes has still to be developed. In recent years, pinealectomy in young chickens has consistently produced scoliosis that has many characteristics similar to those

2

f- Nettc et ul. / The Effects of Exposure to Intense. 24h Lit>ht

seen in patients with AIS [2,3] and this model has considerable potential. Unfortunately, the mechanism underlying this phenomenon in young chickens has yet to be elucidated and its transference to a mammalian model has yet to be established. The main product of the pineal gland is melatonin [4] and consequently many studies have focused on the effects of reduced levels of this hormone as the main contributing factor to the development of the scoliosis. Disturbingly, the results from some of these studies are contradictory and the role played by melatonin remains confused. The surgery associated with pinealectomy is extensive especially for such young animals and it has yet to be established conclusively that the underlying cause for the development of the scoliosis is the actual removal of the pineal gland and not some subtle artifact of the surgery. Certainly, low levels of serum melatonin seem to be associated with the development of scoliosis in this model but the actual role of melatonin remains to be established. The hormone melatonin is produced only while the animal is in the dark and creates a circadian rhythm [5]. For this experiment, it was hypothesized that an environment of continuous, intense light would produce reduced levels of melatonin similar to those seen following pinealectomy. The results of such a situation would show whether or not the surgery itself was an integral part in the production of the phenomenon as well as providing information which would help to clarify the role of reduced levels of serum melatonin.

2. Materials and Methods First Experiment Twenty-six, newly-hatched Mountain Hubbard (broiler) chickens were obtained from Lillydale hatchery in Udmonton. Ten of the chickens were randomly selected and placed in a 12-hour light-dark cycle (12D12L) to act as normal controls. The other 16 chickens were subjected to continuous, bright light (24L) with no dark component and acted as the experimental group. The chickens remained in their two groups in these environments for the entire experiment. A review of the literature indicated that a brightness of at least 700 lux would be required to reduce serum melatonin levels to zero [6]. Therefore, it was decided that a brightness of at least 1000 lux would be used for both the controls during the light cycle and continuously with the experimentals. This level of brightness was achieved through the use of two sets of floodlights in each room and a photometer was used to monitor the brightness each day. The two groups were housed in different rooms because of the different lighting conditions but the environmental conditions in the two rooms were kept identical. Both the experimental and control groups were given food and water ad libitum. Throughout the entire study, the chickens were observed closely several times a day, particularly for the development of any health problems.

F. Nette et al. / The Effects of Exposure to Intense, 24h Light

Collection of Blood Samples and Radioimmunoasssay Methodology Collection of blood samples for the analysis of serum melatonin levels occurred on day 15. At the time corresponding to the middle of the light cycle, 8 of the experimental and 5 control chickens were randomly chosen. The anterior chest wall was opened so that 1 ml of blood could be collected easily from each chicken directly from the left ventricle. This procedure was repeated with a similar number of chickens at the time corresponding to the middle of the dark phase on the same day. Collection in the dark required using a red light in the 1 2D 1 2L group to ensure that melatonin secretion was not affected. Unfortunately, 1 ml of blood is required for melatonin analysis and chickens of this age cannot survive the removal of this amount of blood, necessitating euthanasia. The analysis is described in further detail in previous publications [7]. Second Experiment One hundred and sixty, newly-hatched Mountain Hubbard chickens were obtained. They were randomly separated into 4 groups of 40 chickens each. Two of the four groups were chosen randomly and subjected to pinealectomy surgery. The chickens in the other two groups did not undergo surgery and acted as normal controls. One pinealectomised and one normal group were placed in a single, controlled environment on a 12-hour, light-dark cycle (1 2L 1 2D) at >1000 lux for the entire experiment. These two groups were identified as the "control pinealectomised" and the "control normals" respectively. The other two groups of chickens formed the experimental groups and were subjected to 24-hours of intense, bright light (24L) also at >1000 lux. These two groups were identified as the "experimental pinealectomised" and the "experimental normals" respectively. Collection of Blood Samples and Radjoimmunoassay Methodology Collection of blood samples for analysis of serum melatonin using radioimmunoassay techniques occurred twice during the experiment: on days 15 and 22. At the time corresponding to the middle of the light phase on day 15,10 chickens from the experimental pinealectomised group, 10 chickens from the experimental normal group, 10 chickens from the control pine alectomised group and 10 chickens from the control normal group were randomly chosen. This procedure was repeated in the middle of the dark cycle. Again, this required using a red light in the 12L12D group when collecting the samples to ensure that hormone levels were not affected. On day 22 at the time corresponding to the middle of the light cycle, 10 experimental pinealectomised, 10 experimental normals, 10 control pinealectomised and 10 control normals were randomly chosen. Each chicken was weighed and marked using a permanent marker. One ml of blood was collected from a wing vein of each chicken. The chickens were replaced into their respective rooms after the collection of blood was completed. The procedure was repeated at the time corresponding to the middle of the dark cycle with the remaining experimental and control chickens. Separate chickens were used for the collection of blood in the dark cycle to avoid any changes to serum melatonin levels if blood collection had occurred earlier in the day as well.

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F. Nette et ul. / The Effects of Exposure to Intense, 24h Light

3. Results First Experiment The results of the serum assays in the first experiment are shown in Figure 1.

Figure 1. Average serum melatonin values from the first experiment in which blood samples were collected afier IS days. Control chickens (Control) were exposed to a 12:1 2h Iight:dark cycle whereas the experimental (Expt) group was exposed to 24h light. Blood was collected at a time corresponding to the middle of the dark phase (Midnight) and the middle of the light phase (Noon). Note the circadian rhythm in the control group of chickens and the lack of a rhythm in the experimental group.

Second Experiment The results from this experiment are shown in Figure 2.

Figure 2. Average serum melatonin values from the second experiment in which blood samples were collected after IS days. The control chickens (Control) were exposed to a 12: 12h light:dark cycle whereas the experimental (Expt) group was exposed to 24h light. Blood was collected at a time corresponding to the middle of the dark phase (PM) and the middle of the light phase (AM). Note that the average serum melatonin level in the control, normal group of chickens in the middle of die dark cycle was significantly larger than any of the other values. Note too that the average values in all groups where die chickens had been pinealectomised showed low levels of serum melatonin. ilowever, while die normal chickens in die experimental conditions (24h light) did not show a circadian rhythm, these average results were significantly larger than those found in all groups of pinealectomised chickens.

The data for the blood samples collected during the middle of the light phase after 22 days are shown in Figure 3. Figure 4 shows the results collected at the time corresponding to the middle of the dark phase after 22 days. Measurement of the Cobb angles from the radiographs indicated that none of the normal chickens kept in the 12L12D cycle developed scoliosis. In contrast, 50% (10/20) of the pinealectomised

F. Nette et al. / The Effects of Exposure to Intense, 24h Light

5

chickens kept in the same conditions did develop scoliosis. Most interestingly, the results also showed that 15% (3/20) of the non-pine alectomi sed chickens in the experimental group (24h continuous, intense light) developed scoliosis whereas 80% (16/20) of the pinealectomised chickens kept in the same conditions (24L) also developed scoliosis. The average degree of scoliosis that developed was not significantly different between any of the groups where some chickens developed scoliosis.

Figure 3. Average serum nielatonin values from the second experiment in which blood samples were collected at the time equivalent to the middle of the light phase after 22 days. The control chickens (C) were exposed to a 12:12h light:dark cycle whereas the experimental (E) group was exposed to 24h light. The chickens in some of the groups underwent pinealectomy (PINX) and some did not (NOR) and acted as controls. The chickens in each group were also divided into those that developed scoliosis (Scol) and those that did not (None). Note that all values of average serum melatonin levels are close to zero but that the values for the experimental normal chickens (24L, non pinealectomised) are significantly greater than some of the other values.

Figure 4. Average serum melatonin values from the second experiment in which blood samples were collected at the time equivalent to the middle of the dark phase after 22 days. The control chickens (C) were exposed to a 12:12h light:dark cycle whereas the experimental (E) group was exposed to 24h light. The chickens in some of the groups underwent pinealectomy (PINX) and some did not (NOR) and acted as controls. The chickens in each group were also divided into those that developed scoliosis (Scol) and those that did not -one). Note that the value for average serum melatonin in the control group of normal chickens (12L12D, not pinealectomised) is significantly larger than all other values which are low.

4. Discussion The results of this study have clearly shown that it is possible to manipulate the serum levels of melatonin in young chickens by using intense, consistent light of >1000


F. Netle et al. /The Effects of Exposure to Intense. 24h Light

lux. Consequently, a method is available by which serum melatonin levels can be reduced to at least close to zero without the extensive surgery associated with pinealectomy. Perhaps the most significant result from this study is that 15% of the normal chickens that were exposed to intense, continuous light developed scoliosis. In addition, while it was expected from the results of previous experiments that approximately 55% of the pinealectomised chickens would develop scoliosis (actually 50% in this experiment), the results showed that this figure was increased to 80% when the chickens were exposed to the intense light after being pinealectomsied. These are exciting results because they suggest that reduced levels of melatonin are certainly involved in the development of the scoliosis and are not just correlated to the phenomenon. These results suggest that that there is possibly a threshold level of serum melatonin below which scoliosis can develop.

5. Acknowledgements The authors would like to thank the Edmonton Orthopaedic Research Association and the Scoliosis Research Society for providing funding for this work.

References 1. 2.

3.

4. 5. 6. 7.

R.C. Robin, The Aetiology of Idiopathic Scoliosis. CRC Press, Boca Raton, 1990. Wang X, Jiang II, Raso VJ, Moreau M, Mahood J, Zhao J, Bagnall KM. Characterization of the scoliosis that develops following pinealectomy in the chicken and comparison with the scoliosis seen in adolescent idiopathic scoliosis in humans. Spine 1997; 22:17-25. Wang X, Moreau M, Raso JV, Zhao J, Hongxing J, Mahood J, Bagnall KM. Changes in serum melatonin levels in response to pinealectomy in the chicken and its correlation with development of scoliosis. Spine 1998; 23:2377-2382. Pelham RW. A serum melatonin rhythm in chickens and its abolition by pinealectomy. Endocrinology, 7975, 96-2: 543-46. Binkley S. The pine-: endocrine and neuroendocrine function. Englewood Cliffs, NJ: Prentice Hall, 1988:246-61. Classen I1L, Riddell C, Robinson FE. Effects of increasing photoperiod length on performance and health of broiler chickens. British Poultry Science 1991; 32:21-29. Bagnall KM, Raso vJ, Hi- D, et al. Diurnal and nocturnal serum melatonin levels in girls with adolescent idiopathic scoliosis. Spine

77i.fi. Grivas(Ed.) Research into Spinal Deformities 4 IOS Press, 2002

Is the labyrinthine dysfunction a causative factor in idiopathic scoliosis? G.Kapetanos*, M. Potoupnis, Ang. Dangilas, K. Markou, J. Pournaras A' Orthopaedic Department - Aristotelian University of Thessaloniki - Greece ENT Department, "G. Papanikolaou " Hospital - Thessaloniki

*8 Martiou Str. Panorama - Thessaloniki - Greece — Post code:55236 Tel:+ 30310344271 - Fax:+ 303103442 71 Abstract. The cause of idiopathic scoiiosis remains unknown, although research has possibly eliminated some hypothetical causes. Recent reports associating scoliosis convexity with equilibrium control central processing and motor lateralization have suggested that idiopathic scoliosis is connected causally with the motor cortex. In order to analyze these factors a study of labyrinthine function was carried out. This study included seventeen female patients 12 to 14 years old (mean age= 13.36y) with right thoracic idiopathic scoliosis and twelve normal control females 12 to 14 years old (mean age =13.1y).An electro-nystagmographic study of labyrinthine function (potential nystagmus) was performed in all the patients of the study with caloric tests. The nystagmus was recorded with the electronystagmographic technique (ENG) using Hartmann device. We evaluate these parameters: Slow phase velocity (SPY), Total amplitude (Tamp), Frequency of nystagmus (Freq). No children of the study presented spontaneous nystagmus. No correlation was found between the convexity of the curvature and the direction of nystagmus in posture tests. There were no significant differences between left- and right- beating nystagmus. The results are discussed with special reference to aetiology in idiopathic scoliosis.

Idiopathic scoliosis is a three-dimensional deformity of the spine with lateral curvature combined with vertebral rotation. Although the clinical manifestations of this disease have been well described, no one has been able to determine the cause and pathogenesis [1,2]. The cause of idiopathic scoliosis remains unknown, although research has possibly eliminated some hypothetical causes [4,10]. The fact that many patients with idiopathic scoliosis appear to be out of balance has led many researchers to postulate that a brain stem abnormality involving the vestibular system is the cause of this condition [6,8,9]. The aim of this study was to evaluate the postural effects on nystagmus response during caloric vestibular stimulation. The study included seventeen female patients 12 to 14 years old (mean age=13.36y) with right thoracic idiopathic scoliosis (study group). All patients had a single major structural curvature between 20°-40° [3]. The control group comprised twelve non-scoliotic healthy subjects in the same age group (mean age=13.1y) and with about the same sex ratio. In all patients of the study an electronystagmographic study of labyrinthine function with caloric stimulation was performed. The recordings were performed in a

G. Kapctanos et al. / I s the Lahyrinthine l~)\sfunction a Causative h actor'

dark, silent room with the test subject supine and with eyes closed. Electrodes were placed at each outer canthus for recording horizontal nystagmus (?]. The caloric tests were performed according to the method of Fitzgerald and Hallpike with slight modifications [5]. The syringings were performed with carefully controlled temperatures 30°C and 44°C in each ear. The following four test situations were studied in the supine position with the subject's head in 30° flexion. Warm water 44°C in the right ear, warm water in the left ear, cold water 30°C in the left ear and cold water in the right ear. The syringing was performed for 45 seconds with a water volume 250cc. The time between two syringings was lOminutes. The recording time in each position was at least 60 seconds. The direction of nystagmus and intensity were registered. We evaluated these parameters for each patient: The frequency of nystagmic movements, the amplitude of nystagmic movements and the slow phase velocity of nystagmus. Therefore we determined the difference in sensitivity between the labyrinths and between left- and right- beating nystagmus in relation to the total response. These differences in labyrinthine sensitivity, evaluated with the use of unilateral weakness parameter. The differences in left- and right- beating nystagmus evaluated with the use of directional preponderance parameter. No one children of the study present spontaneous nystagmus or positional nystagmus. No significant correlation was noted between direction of convexity and nystagmus. Five patients from the study group (29.4%) revealed preponderance of the right-beating nystagmus. Four patients of the study group (23.5%), revealed unilateral weakness (difference between left and right labyrinth>20%) with dominance of the right labyrinth. Twelve patients from the study group (70.5%) did not reveal unilateral weakness (difference between left and right labyrinth <20%) [table 1]. No one of the control group revealed unilateral weakness (difference between left and right labyrinth <20%). These differences didn't reach any statistical significance (p>0.05, Chi-Square test).

SPY values

Study group

Study group

Pathological

Physiological

values

values

Pts=5 Mean

SD

Pts=12 Mean

SD

SPY 44°C R

8.15°/sec

6.72

7.88°/sec

4.51

SPY 44°C L

5.1°/sec

1.44

7.36°/sec

5.49

5PV 30°C L

7.78°/sec

2.27

10.54°/sec

7.95

SPY 30°C R

9.65°/sec

2.72

11.82°/sec

6.73

Table 1: Study group - SPY values

G. Kapetanos et al. / I s the Labyrinthine Dysfunction a Causative Factor?

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Finally, four patients from the study group revealed both right unilateral weakness and directional preponderance, while only one patient revealed right directional prepoderance. From the above results we conclude that in four patients from the study group the right labyrinth was the preponderant. In nine patients from the study group the scoliotic curvature was between 20°30°. Only one of these patients (11%), revealed right directional preponderance. In eight patients from the study group the scoliotic curvature was between 30°-40°. Three patients of this subgroup (37.5%), revealed right directional preponderance. These differences did not reach any statistical significance (p>0.05, Chi-Square test). This study is continuing with increase the number of subjects. The result of this study reveal that is difficult to draw any conclusions as to whether a vestibular imbalance may be a contributory factor to adolescent idiopathic scoliosis or whether the vestibular findings are secondary to the deformity of the spine. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Burwell R.G., Cole A.A., Cook T.A., et al: Pathogenesis of idiopathic scoliosis. The Nottingham Concept. Acta Orthop. Belg. 58(suppl.l):33-58,1992 Burwell R.G, Agadir M, Austin D.J, Cole A.A, Cook J.A, Grivas T.B, Jones F.A, et al: Pathogenesis of idiopathic scoliosis. A multifactorial concept. J.Bone Joint Surg. 75-8:174,1993 Cobb J.R.: Outline for the study of scolosis. In Instructional Course Lectures, The American Academy of Orthopaedic Surgeons. Vol.5,pp.261-275. Ann Arbor, J.W.Edwards, 1948. Dickson R.A.: Spinal deformity - Adolescent Idiopathic Scoliosis. Spine 24(24):2601-2606,1999 Fitzgerald G, Hallpike C.S: Studies in human vestibular function. Observations on the directional preponderance (nystagmusbereitschaft) of caloric nystagmus resulting from cerebral lesions. Brain,65:115,1942 Sahlstrand T, Ortengren R, Nachemson A.: Postural equilibrium in adolescent scoliosis. Acta Orthop. Scand. 49:354,1979 Sahlstrand T., Petruson B.: Postural effects on nystagmus response during caloric labyrinthine stimulation in patients with adolescent idiopathic scoliosis. Acta Orthop.Scand. 50: 771-775,1979 Sahlstrand T., Petruson B., Ortengren R.: Vestibulospinal reflex activity in patients with adolescent idiopathic scoliosis. Postural effects during caloric labyrinthine stimulation recorded by stabilometry. Acta Orthop. Scand 50(3):275-281, 1979 Wiener-Vacher S.R., Mazda K.: Asymmetric otolith vestibulo-ocular responses in children with idiopathic scoliosis. The Journal of Pediatrics, 132(6): 1028-1032,1998 Willner S.: Adolescent idiopathic scoliosis: Etiology. In Weinstein SL (ed): The Pediatric Spine: Principles and Practices. New York, Raven Press, p.445,1994

77?. fl. GnvastEd. Research into Spinal Deformities 4 1OS Press. 2<«'2

Is the central nervous system a causative factor in idiopathic scoliosis? M. Potoupnis*, G. Kapetanos, V.K. Kimiskidis, P.P. Symeonides A' Orthopaedic Department - Aristotelian University ofThessaloniki - Greece C' Department of Neurology - Aristotelian University ofThessaloniki - Greece *65 Olinthou Str - Thessaloniki - Post code: 54351 Tel.•+ 30310932013 - Fax:+ 30310932013 - e-mail:[email protected] Abstract: The present study was designed to investigate the involvement of central nervous system (CNS) in the pathogenesis of idiopathic scoliosis.Seventeen female patients with right thoracic idiopathic scoliosis (mean age = 13.36y) and ten normal controls (mean age =12.6y) entered the study. Magnetic stimulation of the brain was performed. Threshold measurements included upper (UT) and lower threshold (LT). Cortical latencies of MEPs during muscle activation were also measured.

Adolescent idiopathic scoliosis is a structural lateral curvature of the spine evidenced in the late juvenile or adolescent period in otherwise normal individuals. Immature individuals with known neuromotor disorders are subject to the development of scoliosis; therefore a subclinical dysfunction or anatomic abnormality of the neurologic system has been hypothesized as a causative factor of adolescent idiopathic scoliosis [1,3]. In previous clinical studies, authors have tested a wide range of functions, including proprioception, postural equilibrium, oculovestibular complex and vibratory sensation and multiple techniques, including electronystagmography, electroencephalography and electromyography in select scoliotic patient populations {2,5,6,7,9]. This study was designed to investigate the involvement of the central nervous system (CNS) in the pathogenesis of idiopathic scoliosis, by measuring the corticomotor threshold in both cerebral hemispheres with transcranial magnetic stimulation [8]. In the study seventeen female patients were included 12 to 14 years old (mean age=13.36y) with right thoracic idiopathic scoliosis (study group). All patients had a single major structural curvature between 20°-40 ° [4]. Ahe control group comprised ten non-scoliotic healthy subjects in the same age group (mean age=12.6y) and with about the same sex ratio. Magnetic stimulation of the brain was performed with a figure of eight coil angled 45JE to the parasagittal plane and positioned so as to overly the hand area [8]. Motor Evoked Potentials (MEPs) were recorded from the first dorsal interosseous muscle. Threshold measurements included upper (UT) and lower threshold (LT), defined as the stimulus intensities producing MEPs with a propability of 100 and 0%, respectively. Mean threshold (MT) was the mean of UT and LT. Cortical latencies of MEP's during muscle activation were also measured.

M. Potoupnis et al. / Is the Central Nervous System a Causative Factor?

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In the patients' right hemisphere UT,MT and LT were 46.5±8.2, 41.6±7.6 and 36.6±7.3% respectively and the activated cortical latency was 18.6±l.lms. In the left hemisphere UT, MT and LT were 45.9±9.8, 41.4±9.1 and 36.9±8.7%, respectively and the activated cortical latency was 18.3±0.8ms. These differences were not statistically significant (p>0.05, t-test). The side-to-side difference of UT,MT and LT were 4.5±2.4,4.3±2.8 and 4.4±3.7. None of all the above parameters differed significantly from those of the control group (p>0.05, t-test). The study is continuing with increase of the number of subjects. The present study did not reveal asymmetries or pathological alterations in the corticomotor excitability of patients with idiopathic scoliosis. Although more research is needed to confirm and determine this problem. References 1. 2. 3. 4. 5. 6. 7. 8. 9.

Barrack R.L., Whitecloud T.S., Burke S.W., Cook S.D., Harding A.F.: Proprioception in idiopathic scoliosis.Spine 9:681-685,1984 Brinker M.R., Willis J.K., Cook S.D., Whitecloud T.S., Bennett J.T., Barrack R.L., Ellman M.G.: Neurologic testing with somatosensory evoked potentials in idiopathic scoliosis. Spine 17:277279,1992 Burwell R.G., Cole A.A., Cook T.A., et al: Pathogenesis of idiopathic scoliosis. The Nottingham Concept. Acta Orthop. Belg. 58(suppl.l):33-58,1992 Cobb JR: Outline for the study of scolosis. In Instructional Course Lectures, The American Academy of Orthopaedic Surgeons. Vol.5,pp.261-275. Ann Arbor, J.W.Edwards, 1948 Herman R., Mixon J., Fisher A., Maulucci R., Stuyck J.: Idiopathic scoliosis and the central nervous system: A motor control problem. Spine 10:1-14,1985 Machida M.: Cause of idiopathic scoliosis. Spine Vol.24-24:2576-2583,1999 Miller N.H.: Cause and natural history of adolescent idiopathic scoliosis. Orthopaedic Clinics of North America, 30(3):343-352, 1999 Mills K.R., Nithi K.A.: Corticomotor threshold to magnetic stimulation: Normal values and repeatability. Muscle and Nerve:570-575, May 1997 Woods L.A., Haller R.J., Hansen P.D., et al: Decreased incidence of scoliosis in hearing-impaired children: Implications for a neurologic basis for idiopathic scoliosis. Spine 20:776, 1995

Th B. Gri\-as(Ed.) Research into Spinal Deformities 4 IOS Press. 2l'H>2

The NOTOM Hypothesis for Idiopathic Scoliosis: Is it Nullified by the Delayed Puberty of Female Rhythmic Gymnasts and Ballet Dancers with Scoliosis? R G Burwell1 & P H Dangerfield2 'The Centre for Spinal Studies and Surgery, Nottingham and2 Department of Human Anatomy and Cell Biology, University of Liverpool and Royal Liverpool Children's Hospital, Alder Hey, Liverpool, UK Abstract. Nachemson [3] suggested that there are more girls than boys with progressive adolescent idiopathic because of a different timing between skeletal maturation and postural maturation in the sexes during adolescence. We termed Nachemson's concept the neuro-osseous timing of maturation (NOTOM) hypothesis and used it to propose a possible medical treatment for idiopathic scoliosis by delaying puberty through the pituitary using gonadorelin analogues as in idiopathic precocious puberty [1,2]. The prevalence of scoliosis is reported to be increased in rhythmic gymnasts (RGs) in Bulgaria [4] and in ballet dancers (BDs) in the USA [S]. Both groups exhibit delayed puberty, which, at first sight, nullifies the NOTOM hypothesis for idiopathic scoliosis. While constitutional and environmental factors may determine these scolioses, the different curve types in RGs and BDs suggest that the exercise pattern over many years determines which type of scoliosis develops, although not the curve severity. We support the view that scoliotic RGs should be included in a group of sportsassociated scoliosis separate from idiopathic scoliosis [4]. Hence the delayed puberty of RGs and BDs with scoliosis does not nullify the NOTOM hypothesis as their scolioses are not idiopathic. There is a need to focus research on such subjects who have defined constitutional and environmental factors related to their scolioses.

1. Nachemson's concept and the NOTOM hypothesis Nachemson [3] suggested that there are more girls than boys with progressive AIS for the following reason. The maturation of postural mechanisms in the nervous system is complete about the same time in boys and girls. Girls enter their skeletal adolescent growth spurt with immature postural mechanisms. So, if they have a predisposition to develop a scoliosis curve, the spine deforms. In contrast, boys enter their adolescent growth spurt with mature postural mechanisms so they are protected from developing a scoliosis curve. We termed Nachemson's concept the neuro-osseous timing of maturation (NOTOM) hypothesis and used it to propose a possible medical treatment for idiopathic scoliosis by

R.G. Burwell and P.M. Dangerfield / The NOTOM Hypothesis

\3

delaying puberty through the pituitary using gonadorelin analogues as in idiopathic precocious puberty [1,2].

2. The delayed puberty of rhythmic gymnasts and ballet dancers The prevalence of scoliosis is reported to be increased in rhythmic gymnasts (RGs) in Bulgaria [4] and in ballet dancers (BDs) in the USA [5]. Both groups exhibit delayed puberty, which, at first sight, nullifies the NOTOM hypothesis for idiopathic scoliosis.

3. Comparison of certain dietary, exercise, physical, biological and scoliosis features of rhythmic gymnasts and ballet dancers There are similarities between scoliotic RGs and BDs that include intensive exercise from a young age, dieting, delayed menarche, increased scoliosis prevalence (RGs 12%, BDs 24%), mild scoliosis curves (10-30 degrees), and presumably generalized joint laxity. Other differences in addition to country of origin and exercises, include certain anthropometric features and importantly in RGs, thoracolumbar and lumbar curves and, in BDs, right thoracic curves. 4. Interpretation of the differences between rhythmic gymnasts and ballet dancers We suggest that most BDs who develop mild-moderate scoliosis do not have idiopathic scoliosis but a scoliosis related to intensive exercises over many years acting on a particular phenotype and genotype, similar to the sports-associated scoliosis. We support the view that scoliotic RGs should be included in a group of sports-associated scoliosis separate from idiopathic scoliosis [4]. While constitutional and environmental factors may determine the scoliosis, the different curve types in RGs and BDs suggest that the exercise pattern over many years determines which type of scoliosis develops, although not the curve severity. 5. Conclusions 1. The delayed puberty of RGs and BDs with scoliosis does not nullify the NOTOM hypothesis as their scolioses are not idiopathic. 2. There is a need to focus research on rhythmic gymnasts and ballet dancers who have defined constitutional and environmental factors related to their scolioses.

14

R. G. Burwell and P.H. Dangerfield / The NOTOM Hypothesis

References 1. 2.

3.

4. 5.

R.G. Burwell, Biology is the future of scoliosis treatment. In, Research into Spinal Deformities 3. A. Tanguy, B. Peuchot (eds.), Amsterdam:IOS Press, 2002. R.G. Burwell, P.M. Dangerfield, A possible neuroendocrine method for delaying the adolescent growth spurt and slowing scoiiosis curve progression based on the NOTOM hypothesis: potential of a medical treatment for progressive juvenile and adolescent idiopathic scoliosis (JIS & AIS). Journal of Bone and Joint Surgery (Br) Orthopaedic Proceedings. In Press. A. Nachemson. In the discussion after the paper 'Aetiopathogenesis of idiopathic scoliosis' by R G Burwell. Second Annual Meeting, Societ£ Internationale de Recherche et d'Etude sur le Rachis, Barcelona, 28-30 November 1996. P.I. Tanchev et al., Scoliosis in rhythmic gymnasts. Spine 25(11): 1367-1372, 2000. M.P. Warren et al., Scoiiosis and fractures in young ballet dancers: relation to delayed puberty and secondary amenorrhea. New England Journal of Medicine 314(21):1348-1353, 1986.

Th.B. Grivas (Ed.) Research into Spinal Deformities 4 IOS Press, 2002

Etiologic Theories of Idiopathic Scoliosis: Neurodevelopmental Concepts to be Evaluated R G Burwell1 & P H Dangerfield2 'The Centre for Spinal Studies and Surgery, Nottingham and 2Department of Human Anatomy and Cell Biology, University of Liverpool and Royal Liverpool Children's Hospital, Alder Hey, Liverpool, UK Abstract. There is increasing interest in the concept that neuromuscular mechanisms and the central nervous system (CNS) are somehow involved in the etiology and pathogenesis of idiopathic scoliosis (IS). Yet in the extensive neuroscience research of idiopathic scoliosis certain neurodevelopmental concepts have been neglected. These include: (1) a CNS body schema for posture and movement control generated during development and growth by establishing a long-lasting memory; (2) pruning of cortical synapses at puberty; and (3) neuromorphic engineering. Memory of developing posture and movement might be established in neurons of the CNS body schema in the form of novel proteins; these could be coded by modified genes obtained by the recombination (crossing over) of DNA in a similar way to that in the production of immunological antibodies and during meiosis [11,27]. These concepts need evaluation in relation to (1) the etiopathogenesis of IS and (2) a possible new treatment approach to idiopathic scoliosis involving a neuromorphic device to control the output for muscle stimulators that are inserted and driven with telemetry.

l. Introduction There is increasing interest in the concept that neuromuscular mechanisms and the central nervous system (CNS) are somehow involved in the etiology and pathogenesis of adolescent idiopathic scoliosis [2-4,6,12,13,24,34-36]. Bagnall [3] outlines how neurological dysfunction associated with the feedback mechanism between ligaments and muscles might be involved in some cases of adolescent idiopathic scoliosis. Goldberg [16] takes a cautionary position and asks that supporters produce convincing evidence of a '...conclusive of a significant and meaningful abnormality in an overwhelming proportion of patients and absence in controls.' In the extensive neuroscience research of AIS certain neurodevelopmental concepts have been neglected. 2. A CNS internal body image or body schema generated during growth Postural control involves the capacity to build up internal representations for organizing sensory inputs and co-ordinating them with motor actions. The central nervous system matures with an internal body image, or CNS body schema, of posture

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R.G. Rtirv'll and PH. nangerfield / Etiologic Theories of Idiopathic Scoliosis

and movement derived from proprioceptive, vestibular and visual input, to which heredity and learning contribute [17,18,26,32,33]. In this connection Shumway-Cook and Woollacott [32] note that in development, new behaviours and skills emerge from an interaction of the child and its maturing nervous and musculoskeletal system with the environment. An important part of interpreting senses and co-ordinating actions for postural control is the presence of an internal representation, or CNS body schema, providing a postural frame of reference. It has been hypothesised that this postural frame of reference acts as a comparator for incoming sensory inputs as an essential part of interpreting self-motion, and to calibrate motor actions. The CNS body schema concept implies that during development the effects of musculokeletal growth on body size and shape may involve the sensory inputs adjusting the CNS body schema so that it is unique for each individual ensuring that the motor control is established appropriately for that individual. This would involve storage in a long-lasting memory system, or systems, such as: • structural modifications of synaptic connections (neuronal plasticity at synapses due to the activation of protein kinases), resulting in alterations in the patterns of neural activity [15, 29,30], or • possibly other systems including proteins or memory coding by modified genes in brain DNA [11,15,27]. Changes in gene expression are considered essential for structural synaptic modifications [27]. Memory might be established in neurons of the CNS body schema in the form of novel proteins coded by modified genes obtained by the recombination (crossing over) of DNA in a similar way to that (1) in the production of immunological antibodies and (2) during meiosis [11,27]. According to this concept the DNA changes in response to new sensory experiences during development and growth and is stored. We suggest that idiopathic scoliosis might result from an abnormality in establishing this internal body image, or body schema within the central nervous system during development and growth. The defect may be in the DNA of neurons in the CNS body schema and specifically how the DNA sequences change in response to sensory inputs during development and growth. This concept links postnatal growth, posture, movement, somatotopic localisation in the CNS, memory and genetics. Perturbations of the CNS body schema evidently occur in some neurological disorders such as phantom limb and a wide variety of psychiatric disorders including schizophrenia (dysmorphic concern) [5]. 3. Pruning of cortical synapses at puberty Around the time of puberty in humans much of the synaptic architecture is broken down and remodeled; the onset of puberty coincides with the final regressive event in the CNS - elimination of 40% of neuronal synapses [19, 20-23]. In general, synapse elimination is thought to reflect a process where early in development synaptic contacts are made randomly. Then, in the subsequent course of development, only those connections that are stabilised are incorporated into functioning units or circuits, whereas those not incorporated become inactive and are eventually resorbed [23]. Competition for

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a trophic factor, nerve growth factor (NGF), has been suggested as the underlying physiological mechanism [29,30]. Such pruning of synapses is thought to increase the efficiency of cognitive function that only emerges in adolescence [23]. Neuropathologic, EEG and brain metabolic studies provide evidence for peaks of cortical synaptic density around 4-10 years of age followed by decline during adolescence [7,8,23,28]. The pruning of cortical synapses at puberty might affect the development of the CNS body schema and alter the development of the symmetry of motor control of the trunk. This could contribute to the development of idiopathic scoliosis. According to Saugstad [31] early puberty results in an earlier end to synaptic pruning, increased synaptic connectivity in the cerebral cortex and increased risk of manicdepressive psychoses. In late maturers prolonged synapse elimination should lead to a lower cortical synaptic density, reduced synaptic connectivity and a diathesis for schizophrenia [25]. Are these psychoses related epidemiologically to adolescent idiopathic scoliosis? In schizophrenia there is an excess of ill-defined conditions in which scoliosis is not mentioned [10]. 4.Neuromorphic engineering Neuromorphic engineers look at brain structures and function and devise chips that contain neurons, axons and a primitive rendition of brain chemistry [1]. At the Telluride Workshop of 2001 [1] research was presented that involved the collaboration of a biologist (Avis Cohen who studies generation of swimming in lampreys), a robotics engineer and an analogue chip designer to create a tethered biped that uses the principle of the central pattern generator (cpg). In the biped, there is a small pair of legs, driven at hips with the knees allowed to move freely, swinging forward and backward under their own momentum. To make the robot walk, the hips are driven forwards and backwards by bursts of electrical energy triggered by the cpg. The robot has sensors that let it feel and respond to the hip angle. Because outputs from these sensors are fed directly back to the cpg, the robot literally learns to walk. The cpg works by charging and discharging an electrical capacitor. The clinical application of this model is a neuroprosthetic device for spinal cord injury patients. In discussing this work with Professor Avis Cohen [9] we asked if the concepts involved in their neuromorphic model might be applied to idiopathic scoliosis in (1) patients, and (2) finite element models. The aim would be to control the muscle contractions and make them more symmetric. Professor Cohen [9] advised that the neuromorphic device could be used to control the output for muscle stimulators that are inserted and driven with telemetry. The device is able to 'learn' to change its output with sensory feedback, say of asymmetry. This would allow the pattern of stimulation to change as the patient begins to change her output pattern. Dr Cohen writes, "Once it's known what the muscle activation patterns are, and their pattern of abnormality, it shouldn't be too difficult to take the device to the next stage. Presently there are stimulators (developed by Gerry Loeb at the University of Southern California) that can be implanted in muscles which the device could control."

R. G. Runvell and P H Dangerfield / Etiolngic Theories of Idiopathic Scoliosis

The limitation at present to the possible application of this neuromorphic model to the treatment of idiopathic scoliosis is lack of knowledge about the muscles that might trigger/exacerbate the spinal deformity. References 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.

Anonymous, Machines with a human touch. The Economist Technology Quarterly, September 22nd pp 28-30, 2001. K.M.Bagnall, Debate 1, Adolescent idiopathic scoliosis: Is the cause neuromuscular? The case for. In: Stokes IAF (ed.), In: Research into Spinal Deformities 2, pp 91-93. Amsterdam:IOS Press, 1999. K.M. Bagnall, Ligaments and muscles in adolescent idiopathic scoliosis. Spine:State of the Art Reviews 14(2):447-457, 2000. R.G. Burwell, P.H. Dangerfield, Adolescent idiopathic scoliosis: hypotheses of causation. Spine:State of the Art Reviews 14(2):319-333, 2000. D.J. Castle, K.A. Phillips (eds.), Disorders of Body Image, Petersfield UK & Philadelphia USA: Wrightson Biomedical Publishing Ltd, 2002. J. Cheng, Posterior tibial nerve somatosensory cortical evoked potentials in adolescent scoliosis. Spine 23:332-337,1998. C. Chiron et ai, Changes in regional cerebral blood flow during brain maturation in children and adolescents. Journal of Nuclear Medicine 33:696-703, 1992. H.T. Chugani et ai. Positron emission tomography study of human brain functional development. Annals of Neurology, 22:487-497, 1987. A. Cohen, Personal communication, 2002. A. Dalmau et ai, Somatic morbidity in schizophrenia - a case control study. Public Health lll(6):393-397, 1997. A. Dietrich, W. Been, Memory and DNA. Journal of theoretical Biology 208, 145-149, 2001. J. Dubousset, Les scolioses dites idiopathiques. Definition, pathologic, classification, etiologie. Bulletin Academic Nationale de Medicin 4:699-704, 1999. M. Edgar, Neural mechanisms in the etiology of idiopathic scoliosis. Spine: State of the Art Reviews 14(2):459-468, 2000. I. Feinberg, Schizophrenia: caused by a fault in programmed synaptic elimination during adolescence. Journal of psychiatric research 17(4): 319-334, 1982/3. B. Furlow, You must remember: how do we hold onto memories for a lifetime? Could our histories be inscribed in our genes? New Scientist, No 2308, 15 September, 2001. C.J. Goldberg, Debate 1, Adolescent idiopathic scoliosis:Is the cause neuromuscular? The case against. In:Stokes IAF (ed,). In: Research into Spinal Deformities 2, pp 94-97. AmsterdanrlOS Press, 1999. V.S Gurfinkel, Y.S. Levick, Perceptual and automatic aspects of the postural body scheme. In, Brain and Space, J Paillard (ed.) pp 147-162, 1991. H. Head, G. Holmes, Sensory disturbances from cerebral lesions. Brain 34: 102-244, 1911. D. Horrobin, The Madness of Adam and Eve. London: Bantam Press, 2001. P.R. Huttenlocher, Synaptic density in human frontal cortex - developmental changes and effects of aging. Brain Research 163:195-205, 1979. P.R. Huttenlocher, Synaptogenesis in human visual cortex - evidence for synapse elimination during normal development. Neuroscience Letters 33:247-252, 1982. P.R. Huttenlocher, Synaptogenesis in human cerebral cortex. In, G. Dawson, K.W. Fischer (eds.). Human Behaviour and the Developing Brain, pp 137-152, New York; Guilford. J. Kaiser, J.H. Gruzelier, Timing of puberty and EEG coherence during photic stimulation. International Journal of Psychphysiology 21: 135-149, 1996. M. Machida, Cause of idiopathic scoliosis. Spine 24(24):2576-2583, 2000. T.H. McGlashan, R.E. Hoffman, Schizophrenia as a disorder of developmentally reduced synaptic connectivity. Archives of General Psychiatry 57(7):637-648, 2000. J. Paillard (ed.), Brain and Space, Oxford University Press, 1991.

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27. 28. 29. 30.

31. 32.

33. 34. 35.

36.

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S. Pe_a de Ortiz, Y. Arshavsky, DNA recombination as a possible mechanism in declarative memory: ahypothesrs. Journal ofNeuroscience Research 63, 72-81,2001. A. Pfeifferbaum et al, A quantitative magnetic resonance imaging study of changes in brain morphology from infancy to late adulthood. Archives of Neurology 51: 874-887,1994. D. Purves, J.W.Lichtman, Elimination of synapses in the developing nervous system. Science 210: 153-157,1980. D. Purves, G.J. Augustine, D. Fitzpatrick, L.C. Katz, A-S Lamantia, J.O. McNamara, S.M. Williams (eds.), Chapter 25, Plasticity of mature synapses and circuits, pp 535-562, In, Neuroscience, Second Edition, Sunderland Massachusetts: Sinauer Associates Inc., 2001. L.F. Saugstad, Age at puberty and mental illness: towards a neurological aetiology of Kraepelin's endogenous psychoses. British Journal of Psychiatry 155: 536-544, 1989. A. Shumway-Cook, M.H. Woollacott, Motor Control: Theory and Practical Applications. Second Edition, Chapter 8, Development of Postural Control, pp 192-221, Philadelphia: Lippincott Williams &Wilkins,2001. A. Sirigu et al., Multiple representations contribute to body knowledge processing: evidence from a case of autotpagnosia. Brain 114: 629-642, 1991. T.K.F. Taylor, The brain stem and adolescent idiopathic scoliosis: a hypothesis. Spine:State of the Art Reviews 14(2):477-481,2000. A.G. Veldhuizen et al., The aetiology of idiopathic scoliosis: biomechanical and neuromuscular factors. European Spine Journal 9(3):178-184,2000. scoliosis. European Spine Journal 8(4):252-260,1999. J.B. Williamson, Postural control. Spine:State of the Art Reviews 14(2):469-476

Th.R. Grna.slEd.i Research into Spinal Deformities 4 IOS Press. 2H()2

Study of the rib cage deformity in children with 10°-20° of Cobb angle Late Onset Idiopathic Scoliosis, using Rib-Vertebra Angles Aetiologic implications Theodores B Grivas, Panagiotis Samelis, Theodores Chadziargiropoulos, Basilios Polyzois Scoliosis Clinic, Orthopaedic Department, "Thriasio" General Hospital G. Genimata Avenue, Magula, 19600 Greece E-mail: [email protected] Abstract. The aim of the study is to compare the rib-vertebra angles (RVAs) between children with 10° - 20° of Cobb angle late onset idiopathic scoliosis (LOIS) and non-scoliotic children. Materials and Method: The RVAs of 47 children, with mean age 12.4 years, who presented LOIS with a Cobb angle 10° - 20°, were studied. The children were classified into three groups according to the site of the scoliotic curve: 17 children had thoracic (T), 14 children had thoracolumbar (TL) and 16 children had lumbar (L) curves. The RVAs of the scoliotic children were compared to the RVAs of 60 nonscoliotic children of a similar age group, who were studied in the past. Results: The comparison of the right and left RVAs within each group showed that the children who had: T curves differ at the level T4, T5, T6, T7 and T8, TL curves differ at the level T3, and L curves differ at the level T7 and T12. The comparison of the ipsilateral RVA's between the scoliotic groups showed that between: T and TL curves there are no differences at any thoracic level, between T and L curves the RVAs differ at the T7 level on the right side, whereas mere are no differences between the RVAs on the left side, between TL and L curves the RVAs differ at the level TS, T6, and T7 on the right and at the level TS on the left side. Comparing the RVAs between the scoliotic and nonscoliotic children, it was apparent that the scoliotic children rib cage had lower RVAs (p<0.01) at almost all thoracic levels. Discussion: It has been reported that RVAs is an expression of the resultant muscle forces, which act on each rib. It was also suggested that RVA asymmetries by weakening the spinal rotation-defending system are aetiological for idiopathic scoliosis, (Burwell et al 1992). This study shows that scoliotic children with small curves have underdeveloped thoracic cage compared to nonscoliotic counterparts. The differences are more apparent in the scoliotic children with thoracic curves. It is suggested that the differences of the RVAs between right and left side in this group are an expression of asymmetric muscle forces acting on the thoracic cage. It is concluded that asymmetric muscle forces participate in the pathogenesis of idiopathic scoliosis on the thoracic cage, which deforms early.

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1. Introduction The Difference of the Rib - Vertebra Angle (RVAD) of the apical vertebra was first used by Mehta in 1972 [1] in an attempt to predict whether an infantile scoliotic curve would resolve or progress. Tolo and Gilespie (1978) [2] found that serial measurements of the RVAD are useful in the evaluation of brace treatment of juvenile IS. They even formulated guidelines about modification of brace treatment based on monitoring of the RVAD. Some years later (1985), Kristmundsdottir et al found that the RVA on the convexity of the infantile scoliotic curve correlates significantly with the spinal curve angle, which was not the fact for the respective RVA on the concavity of the curve [3]. Later Wojcic et al (1990) used segmental RVAs in order to study the thoracic cage of scoliotic children postoperatively [4]. Grivas et al (1992) showed that scoliotic children have a narrow upper chest (T1-T4) compared to nonscoliotic children and that the pattern of the scoliotic chest resembles to the funnel shaped thorax of the embryo [5]. Other authors have studied the segmental RVAs in preoperative scoliotic children (Withers et al 1990, Thirvall et al 1991). Measurements of the RVA difference in humans but also in experimentally induced scoliosis in animals have been performed by Xiong et al [6]. The purpose of this report is to emphasize the significance of the segmental RVAs as a useful research tool in the study of idiopathic scoliosis. 2. Materials and Method The segmental RVAs of 47 children, with mean age 12.4 years, who presented late onset idiopathic scoliosis with a Cobb angle 10° - 20°, were studied. The children were classified into three groups according to the location of the scoliotic curve: 17 children had thoracic (T), 14 children had thoracolumbar (TL) and 16 children had lumbar (L) curves. The RVAs of the scoliotic children were compared to the RVAs of 60 nonscoliotic children of a similar age group, who were studied in the past. In an attempt to restrict any possible confounding factor only children with at least one right-sided thoracic curve (primary or compensatory) were included in the study. The segmental RVAs were measured using the following technique (figure 1): a line perpendicular to the middle of the upper end plate of the vertebral body is drawn. Two points are determined on the respective rib: one at the middle of the head of the rib and the second at the middle of the distance between the head of the rib and the point were the rib reaches the lateral chest outline (midhead to midshaft). The angle between these two lines is the segmental RVA. This method allows measurement of the RVAs at the upper ribs, in which the neck is not always visible on the radiographs, or is too short, so the classic Mehta method would not give accurate and repeatable results. 3. Results The segmental RVAs of scoliotic and nonscoliotic children were plotted on the same diagram (figure 2) and the t value of their difference at each thoracic level was calculated.

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The comparison of the right and left RVAs within each group showed that the children who had: 1. T curves differ at the level T4, T5, T6, T7 and T8 2. TL curves differ at the level T3 3. L curves differ at the level T7 and T12. It is concluded that the within group asymmetry is more prominent at primary thoracic curves.

Figure 1: the segmenta! RVAs

The compare of the ipsilateral RVA's between the scoliotic groups showed that between: 1. T and TL curves there are no differences at any thoracic level 2. T and L curves the RVAs differ at the T7 level on the right side, whereas There are no differences between the RVAs on the left side 3. TL and L curves the RVAs differ at the level T5, T6. and T7 on the right and at the level T5 on the left side.

Figure 2: the RVA in nonscoliotic (blue line) and scoliotic (green = thoracic curves, green = thoracolumbar curves, red = lumbar curves). "*" means that the respective segmental RVAD between nonscoliotic and scoliotic RVA is statistically significant (p<0.01)

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More interesting is the asymmetry between nonscoliotic and scoliotic children. It is apparent that the rib cage of scoliotic children had lower RVAs (p<0.01) at almost all thoracic levels, which means that the scoliotic rib cage is smaller than the nonscoliotic rib cage.

4. Discussion It is widely accepted that only severe scoliotic curves impair lung function. Pulmonary function tests are seldom abnormal in thoracic deformities with a Cobb angle <60°. Cardiopulmonary symptoms and subjective complaints occur more frequently in patients with thoracic deformities > 90-100° [7]. In such cases, preservation or improvement of lung function is one main goal of surgery. Upadhyay [8] found that the RVAD of scoliotics (mean Cobb angle 59°) correlates well with the percent of predicted value of Vital Capacity, Forced VC, and Forced Residual Capacity. He also used the change in RVA from standing to supine position as an index of the rib cage rigidity. McAlindon et al showed that RVA measurement is highly reproducible and valid [9]. The prominent within group segmental RVA asymmetry in primary thoracic curves compared to thoracolmbar and lumbar curves is attributed to two factors: first, the greater Cobb angle of the primary curve and second, the involvement of more thoracic levels (higher apical vertebra) when the scoliotic curve is entirely located in the thoracic spine. The asymmetry between scoliotic groups was not prominent at many thoracic levels, because the sample of children studied includes only children with one right thoracic (R primary thoracic, R thoracolumbar, R compensatory thoracic) curve. Therefore, it could be said that rib cages with an underlying right thoracic curve have practically the same pattern of RVA asymmetry. The between noscoliotic and scoliotics group RVA asymmetry is significant at almost all thoracic levels, indicating that there is drooping of the ribs in scoliotic children. The RVAs are a functional index which is visible on the chest X-rays. It is concluded that that measurement of the RVAs, whether as apical RVAD or as segmental RVAs gives early information about the process of curve initiation and progression. Significantly asymmetric RVAs have been observed even at Cobb angles of 8°, i.e. before the diagnosis of scoliosis is made [6]. The question is, how does AIS start: as a functional deterioration of the Neuromuscular System or as a structural abnormality of the vertebral bodies and intervertebral discs? Xiong et al 1994 found significant wedging of the vertebral bodies and disks at the coronal plane even at small nonscoliotic curves with a Cobb angle of 4 degrees. Sevastik claims that the pathogenesis of AIS is possibly related to early vertebral changes rather than to asymmetric muscle forces on the rib cage [10]. The thoracic cage is the location of several muscle groups' origins and insertions, which are involved in the function of breathing but also participate in maintaining the posture of the trunk during movement and rest. The RVAs are an expression of the resultant muscle forces, which act on each rib. It has been proposed that RVA asymmetries are aetiological for idiopathic scoliosis because they result in weakening the spinal rotation-defending system [11],

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This study shows that scoliotic children with 10° -20° curves have underdeveloped thoracic cage compared to nonscoliotic counterparts. Children with yet small curves but without lateral spinal profile differences compared to non-scoliotics, as is shown in one of our studies presented in this meeting, have their rib cage apparently already affected. It is suggested that the differences of the RVAs between right and left side in this group are an expression of asymmetric muscle forces acting on the thoracic cage. These differences are more prominent in the thoracic curve group than in the other scoliotic groups. The authors believe that an extraspinal factor, for instance asymmetric muscle forces, precede and then the curve formation initiates and possibly progresses. It is noteworthy to mention the disclosure of asymptomatic underlying syringomyelia in cases with idiopathic thoracic scoliosis [12]. Asymptomatic neurologic abnormality may exert asymmetric forces on the spine. These forces are transmitted mainly through the ribs. After the curve becomes structural, other factors may contribute to further deterioration of the deformity. References 1. 2. 3. 4. 5.

6. 7. 8. 9. 10. 11.

12.

Mehta MH: the rib -vertebra angle in the diagnosis between resolving and progressing infantile scoliosis. JBJS, 54B, 230-243 Tolo VT, Gilespie R: the characteristics of juvenile idiopathic scoliosis and results of its treatment. JBJS 60B: 181,1978 Kristmundsdottir F, Burwell R G, James J I: The rib-vertebra angles on the convexity and concavity of the spinal curve in infantile idiopathic scoliosis. CORR(201):205-209 1985 Wojcic A S, Webb J K, Burwell R G: An analysis of the effect of the Zielke Operation on the rib cage of S-shaped curves in idiopathic scoliosis. Spine, 15(2):81-86 1990 Grivas TB, Burwell RG Purdue M, Webb JK, Moulton A: The rib cage deformity in idiopathic scoliosis - the funnel shaped upper chest I relation to specific rotation as a prognostic factor. An evaluation of chest shape in progressive scoliosis and control children during growth. Surface Topography and Spinal deformity VI, Alberty, Drerup, Hierholzer (ed). Gustav Fischer Verlag, Stuttgart, Jena, New York, 1992, pp.93-109 Xiong B, Sevastik J A, Hedlund R, Sevastik B : Radiographic changes at the coronal plane in early scoliosis Spine, 19(2): 159-164,1994 Lenke L,OKU 6, Chapter 53, 707-711, AAOS 1999 Upadhyay, S. S., Mullaji, A. B., Luk, K. D. K. and Leong J. C. Y.: Spine 1995(20); 22, 1995, pp. 2415-2420,Relation of Spinal and Thoracic Cage Deformities and Their Flexibilities With Altered Pulmonary Functions in Adolescent Idiopathic Scoliosis McAlindon et al R J, Kruse R W :Measurement of rib vertebral angle difference. Intraobserver error and interobserver variation. Spine, 22(2):198-199 1997 Sevastik J: The thoracospinal concept of the etiopathogenesis of Idiopathic Scoliosis. Spine: State of the art reviews 14(2), May 2000, pp391-399 Burwell RG, Cole AA, Cook TA, Grivas TB, Kiel AW, Moulton A, et al 1992: screening, etiology and the Nottingham theory for idiopathic scoliosis. Surface Topography and Spinal deformity VI, Alberty, Drerup, Hierholzer (ed). Gustav Fischer Verlag, Stuttgart, Jena, New York, 1992, pp.93109 Zadeh HG, Sakka SA, Powell MP.Mehta MH: Absent superficial abdominal reflexes in children with scoliosis. An early indicator of syringomyelia. JBJS, 77B:(5) 762-767, Sept 1995.

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Lateral spinal profile in school-screening referrals with and without late onset idiopathic scoliosis 10°-20° Theodores B Grivas, Spyros Dangas, Panagiotis Samelis, Christina Maziotou, Konstandinos Kandris Scoliosis Clinic, Orthopaedic Department, "Thriasio " General Hospital G. Genimata Avenue, Magula, 19600 Greece E-mail: [email protected] Abstract: Introduction. The aim of this report is a) to study the lateral spinal profile, (LSP), in school-screening referrals with and without late onset idiopathic scoliosis of small curves 10° -20° Cobb angle and b) to validate LSP's aetiological importance in idiopathic scoliosis pathobiomechanics. Methods and Material. The spinal radiographs of 133 children, 47 boys and 86 girls with a mean age of 13.28 and 13.39 years respectively and Axial Trunk Inclination (ATI) > 7°, were examined. The Cobb angle was appraised from the anteroposterior standing radiographs and the segmental spinal profile was assessed. A line was drawn down the posterior surface of each vertebral body from Tl to L5 on lateral standing radiographs, and the angle of this line from the vertical was recorded. Intervertebral values for LSP, (ILSP), that is the result of the subtraction of two consecutive spinal levels LSP, were also calculated. The data were then statistically analyzed. Results. The statistical descriptives of LSP and intervertebral LSP are presented for several groups of children, namely in those: 1) with straight spines, 2) with spinal curvature having a Cobb angle less than 10°, and 3) in scoliotic children with a) thoracic, b) thoracolumbar and c) lumbar curves of 10°-20°. A correlation of the LSP with Cobb angle for the various types of curves for boys and girls is also presented. It is shown that the kyphotic segmental angulation is slightly less and the lordotic one almost normal in scoliotics, compared with the values of normal children. It is interesting to note that the LSP correlated with Cobb angle shows: a) a positive correlation pattern at T6, T7, T8 and T9 for thoracic curves of scoliotic boys and b) a negative correlation pattern at T3, T4 and T5 spinal levels of lumbar curves for scoliotic girls. Discussion. The observed differences of the LSP are mainly located at the lumbar spine, suggesting that factors acting on the lumbar spine in sagittal plane contribute to the development of AIS. The minor hypokyphosis of the thoracic spine and its minimal differences observed in the studied small curves with nonscoliotics in this report add to the view that the reduced kyphosis, by facilitating axial rotation, could be viewed as being permissive, rather than as aetiological, in the pathogenesis of idiopathic scoliosis.

1. Introduction The aim of this report is dual: a) to study the lateral spinal profile (LSP) in schoolscreening referrals with and without commencing late onset idiopathic scoliosis, who had

;>.

T.B. Grivas ct at. / Lau-ral Spinal Profile in School-Screening Referrals

small curves (Cobb angle of 10°-20°) and b) to validate LSP's aetiological importance in idiopathic scoliosis pathobiomechanics. 2. Material and Method 2.1 The examined children. 133 school-screened for scoliosis and referred children, 47 boys (35.3%) with a mean age of 13.28 years (range 9-18), and 86 girls (64.7%) with a mean age of 13.39 years (7-18) were included in the study. All these children had an Axial Trunk Inclination (ATI) > 7°. The statistical analysis showed no difference of the age between the boys and girls, thus the studied sample contains homogenous aged population, (independent Samples T-test). The children were separated in the following groups: 1) with straight spine, 2) with curves measuring Cobb angle less than 10°, which is not considered as scoliosis according to SRS, 3) in children with i) thoracic ii) thoracolumbar and iii) lumbar curves. 2.2 The measurements. The Cobb angle was assessed on the standing posteroanterior and the segmental LSP, on the lateral spinal radiographs. The LSP was measured as following: A line was drawn down the posterior surface of each vertebral body from Tl to L5 on lateral standing radiographs, and the angle of this line from the vertical was recorded [8]. Intervertebral LSP values, that is the result of two successive LSP level values subtraction, were also calculated. When measuring the LSP, the forward tilt of a vertebra from the vertical is conventionally termed proclivity and it is deemed positively (+), while the backward tilt of a vertebra against the vertical is termed declivity and is deemed negatively (-) [8]. There are three component angles of sagittal spinal curves - upper proclive, declive and lower proclive angles. The kyphosis angle is a compound measure of sagittal shape - declive angle plus upper proclive angle. The lordosis angle is a compound measure of declive angle and lower proclive angle [2,3]. The point where the upper proclive angle is turned into the declive angle is considered as the first transitional zone of the LSP of the thoracic kyphosis, while the second transitional zone is located at the lumbar or lumbrosacral spine, where the declive angle is turned into the lower proclive angle. 2.3 The statistical analysis. The techniques used included frequencies, descriptives, Kruskal-Wallis test, Pearson Correlation Coefficient and independent Samples T-test, (SPSS). 3. Results The LSP is presented in the following groups of children: 1) with straight spine, 2) with curves measuring Cobb angle less than 10°, which is not considered as scoliosis according to SRS, 3) in children with i) thoracic ii) thoracolumbar and iii) lumbar curves. Statistics (independent Samples T-test) showed that segmental LSP do not differ between boys and girls of the examined population apart from T10; thereby the findings for both sexes are reported together.

T.B. Grivas et al. /Lateral Spinal Profile in School-Screening Referrals

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Figure 1. The Lateral Spinal Profile for the various groups of children, boys and girls. Yellow bars = thoracic curves, azure bars = Thoracolumbar curves, mauve bars = lumbar curves, line with blue diamonds = straight spines, line with red rectangles = curves with Cobb < 10 dergees.

In the first group (straight spines) 27 children were included, 12 boys [44.4%] and 15 girls [55.6%]. The mean kyphosis (the T4 - T12 Cobb angle reading on lateral spinal radiographs) is 27.1 degrees, and the mean lordosis 30.3 dergrees, (the LI - L5 Cobb angle reading on lateral spinal radiographs). In the second group (curves with a Cobb angle of less than 10°), 13 children were included, 6 boys [46.2%] and 7 girls [53.8%]. The mean kyphosis was 24°, and the mean lordosis 30°. In the third group of children with: i) Thoracic curves with a Cobb angle 10° -20°, 47 children were included, 17 boys [36,2%] and 30 girls [63.8%]. The mean kyphosis was 31°, and the mean lordosis 35.8°. ii) Thoracolumbar curves with a Cobb angle of 10° -20°, 14 children were included (4 boys [28.6%] and 10 girls [71.4%]. The mean kyphosis was 28° and the mean lordosis 32.2°. iii) Lumbar curves with a Cobb angle of 10°-20°, 28 children were included, 7 boys [25%] and 21 girls [75%]. The mean kyphosis was 28.7°, and the mean lordosis 32.6°. The statistical analysis of the LSP's of children with thoracic, thoracolumbar and lumbar curves, using the Kruskal-Wallis non-parametric test, showed no differences among them, apart from L2 and L3 spinal levels and only for girls. Comparing the children's LSP between groups, using Mann-Whitney test, it was shown that: Between the first (straight spines) and the second group (0° -9° Cobb angle), no statistical difference was noticed. Between foe first and the third group with thoracic curves, a difference was found on the T6 level, (p< 0.05). Between the first and the third group with thoracolumbar curves, a difference was found on the L3 level, (p< 0.02). Between the first and the third group with lumbar curves, a difference was shown on the

T.B. Grivas et al. /lateral Spinal Profile in School-Screening Referrals

T4 and L2 level, (p< 0.04 and p< 0.03 respectively). Between the second group of children and the third group with thoracic curves, a statistical difference was shown on the spinal levels T4, (p< 0.02), L2 (p< 0.048) and L3 (p< 0.035). Between the second group and the third group with thoracolumbar curves, a difference was found on the L2 (p< 0.027) and L3 (p< 0.018), spinal levels. Between the second group of children and the third group with lumbar curves, a difference was found on the T4 and L2 spinal levels, (p< 0.04 and p< 0.017 respectively). From the above comparisons it is ascertained that some distinct differences are focused mainly at the lumbar spine. The spinal levels where the first and the second transitional zone appears, relating to the inclination of the LSP (proclive - declive angle) and the maximum value of the above angles are presented in Table 1. In the children of the first group the declive angle from T5-T6 to the T12-L1 is greater than that in the remaining groups of children. The children of the third group, were presenting declive angles from L1-L2-L3 greater than the non-scoliotics, (first and second group), in the contrary at T5-T6 to T12 the declive angle was smaller than in the non-scoliotics. Table 1 Groups of children

First transitional zone * Spinal level

First group Second group (Curves < 10-€ Cobb) Third group Thoracic curves Third group Thoracolumbar curves

T5-T6 T6-T7

Spinal level and maximum value of declive angle TI2(-20.4°) T12 (-18.46°)

Second transitional zone** Spinal level L3-L4 L3-L4

Spinal level and maximum value of proclive angle L5(14-) L5(I5')

T6-T7

TI2 (-20.7°)

L4-L5

L5(165°)

T6-T7

T12(-20.0°)

L4-L5

L5(15.7°)

T12(-I8.7°) L3-L4 T6-T7 L5(16.5<€) Third group Lumbar curves *First transitional zone = conversion of proclive into declive angle. **Second transitional zone = = conversion of declive into proclive angle Table 1: The spinal levels where the first and the second transitional zone, relating to the inclination of the LSP (proclive - declive angle) appears and the maximum value of the above angles, (numbers in parenthesis)

Study of the intervertebral LSP (ILSP), In theirs/ group the larger intervertebral difference of 5.1 ° in the LSP appears at the T4-T5 level (intervertebral disc), while in the lumbar spine, 11.8 °, at the L4-L5 level. In the second group the larger intervertebral difference of 4.5 ° in the LSP appears at the T3-T4 level and then at T7-T8, while in the lumbar spine, 11.8 °, at the L4-L5 level. In the third group with thoracic curves the larger intervertebral difference of 5.2 ° in the LSP appears at the T5-T6 level, while in the lumbar spine, 16.9 °, at the L4-L5 level. In the third group with thoracolumbar curves the larger intervertebral difference of 4.85 ° in the LSP appears at the T6-T7 level, while in the lumbar spine, 15.3°, at the L4L5 level. In the third group with lumbar curves the larger intervertebral difference of 6.1° appears at the T5-T6 level, while in the lumbar spine, 15.7°, at the L4-L5 level.

7.6. Grivas ei al. /Lateral Spinal Profile in School-Screening Referrals

Intervertebral LSP

Figure 2. The intervertebral LSP of the various groups of children. Yellow bars = thoracic curves, azure bars = Thoracolumbar curves, mauve bars = lumbar curves, line with blue diamonds = straight spines, line with red rectangles = curves with Cobb < 10 dergees.

Comparison of the segmental intervertebral LSP (ILSP) of the third -with the first and second group. Mann-Whitney test showed that ILSP of children in group one compared with that of "thoracic " group three was no different, with "thoracolumbar " group three was statistically different at T4-5 (p< 0.02) and Tl 1-12 (p< 0.042), and with "lumbar" group three was statistically different at T5-6 (p< 0.045). Similarly the comparison of group two children's ILSP with that of "thoracic " group 3 was statistically different at T3-4 (p<0.003) and L4-5 (p< 0.042), with "thoracolumbar" group 3 was different at Til-12 (p< 0.042), and with "lumbar" group 3 was different at T5-6 (p< 0.008). Correlation of LSP with Cobb angle for girls and boys. For the girls there is no correlation pattern found for the thoracic and thoracolumbar curves, but only for the lumbar curves at T3, T4 and T5 levels (r = -.532/p< 0.02, r = -.5007 p< 0.02 and r = -.4797 p< 0.03 respectively), where r represents the correlation coefficient and p the statistical significance. For the boys there is no correlation pattern found for the lumbar and thoracolumbar curves, but only for the thoracic curves at T6, T7, T8 and T9 levels (r = 0.5957 p< 0.01, r = 0.618/p< 0.01, r = 0.621/p< 0.01, r = 0.671/p< 0.003, respectively), where r represents the correlation coefficient and p the statistical significance, with the stronger correlation at T9. The readings for ILSP for lumbar spine is consistently more pronounced at the L4L5 level for all groups with values ranging from 11.8_- 16.5_; for the thoracic region the greader readings for ILSP are traced higher for the healthy children (T3-T4, T4-T5) and somewhat lower for the scoliotics (T5-T6, T6-T7) with values ranging from 4.5 ° - 5.2 °

30

7~.fi. Grivas ct ai /Lateral Spinal Profile in School-Screening Referrals

4. Discussion Sagittal spinal angulation (Kyphosis, lordosis and segmental LSP and ILSP) in the study groups. It is evident from our results that the kyphosis is a little smaller and the lordosis almost similar compared with the published values for healthy children [7,8]. The segmental LSP is no different among the studied groups for boys; it is different only for the scoliotic girls for L2 and L3 levels. Correlation of LSP with Cobb angle. It is interesting to note that a) there is a positive correlation pattern at T6, T7, T8 and T9 for thoracic curves of scoliotic boys and b) a negative correlation pattern at 13, T4 and T5 spinal levels for lumbar curves of scoliotic girls. This correlation implies that the LSP or the sagittal angulation is associated or influencing the deformity on the frontal plane at the above spinal levels. LSP and Scoliosis Pathogenesis. In the literature on the aetiology of scoliosis, hypokyphosis is considered a predisposing factor of a scoliosis [1]. It has also been suggested that a flat thoracolumbar profile predisposes an adolescent to idiopathic scoliosis [6]. But equally, the flat thoracolumbar profile could be secondary to the thoracic scoliosis above it. This scientific dilemma should be resolved by the studies of the lateral spinal profile in school screening referrals [8]. This study is addressing the problem whether the sagittal shape deformity or the lateral spinal curve (scoliosis) comes first. Is evident from this study that hypokyphosis is not a predisposing factor of a commencing or small scoliotic curve because there is no difference of the LSP in these curves with the LSP of the respective curves of their healthy counterparts. The minor hypokyphosis of the thoracic spine and its minimal differences observed in the studied small curves when compared with the non-scoliotics in this report add to the view that the reduced kyphosis, by facilitating axial rotation, could be viewed as being permissive, rather than as aetiological, in the pathogenesis of idiopathic scoliosis [4,5]. References 1 2.

3.

4.

5.

Bonne, A. J. 1969 On the shape of the human vertebra! column. Acta Orthop. Belg., 35: 567-583. Burwell, R.G., Upadhyay, S.S., Wojcik, A.S., Bacon, N.C.M., Mouhon, A. and Webb, J.K. (1988). Ultrasound in evaluating scoliosis. In: Proceedings of the Eighth Phillip Zorab Scoliosis Symposium, 26-28 October 1988, London, pp.48-67 Eds. D. Siegler, D. Harrison and M.Edgar. London: Phillip Zorab Scoliosis Research Fund. Burwell, R.G., Patterson, J.F., Webb, J.K. and Wojcik, A.S. (1990). School screening for scoliosis - the multiple ATI system of back shape appraisal using the Scolbmeter with observations on the sagittal declive angle. In: Surface Topography and Body Deformity. Proceedings of the Fifth Internationa] Symposium, 29 September - 1 October 1988, Vienna, Austria Eds. H. Neugebauer and G. Windischbauer, pp. 17-23 Stuttgart: Gustav Fischer. Burwell, R. G., A. A. Cote, T. B. Grivas, A. W. Kiel, A. Moutam, S. S. Upadhyay, J. K. Webb, A. S. Wojcik, and D. J. Wythers 1992 Screening, aetiology and the Nottingham theory for idiopathic scoliosis. In 6th International Symposium on Surface Topography and Spinal Deformity. Hotel Escoril Eden. 1920 September 1990. A. Alberri, R. Drerup, E. Hierholzer (eds.). Stuttgart: Gustav Fischer Verlag, pp. 136J61. Burwell, R. G., Cote, A. A., Cook, T. A, Grivas,T B., Kiel, A. W., Moukxm, A., Thirhvall, A. S., Upadhyay, S. S., Webb, J. K. Wemyss-Holden, S. A., Whitwell, D. J., Wojcik, A. S., and Wythers, D. J.

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(1992) Pathogenesis of idiopathic scoliosis: The Nottingham concept In Symposium on idiopathic scoliosis. Orthopaedica Belgica, Gent, 20-23 March 1991. D. Uyttendaele (ed.). Acta Orthop Belgica. Vol 58, Suppl. I, 1992,33-58. Dickson, R. A., and Archer, I. A. 1984 Scoliosis in the community. In Butterworth's International Medical Reviews, Orthopaedics 2, Management of Spinal Deformities. R. A. Dickson and D. S. Bradford (ed.). London: Butterworths, pp. 77-100. Grivas TB, Baritaki M, Kalamakis N, Kandris K, Polyzois D, Smyrnis P (1998): Normal spinal profile in a Greek high school population sample. 1st Inter-Balkan Congress on Spinal Diseases - Giannestras / Smyrnis Spinal Meeting, 7-9 May 1998. Athens Greece. Kiel A.W., R.G. Burwell, A. Mouhon, M. Purdue, J.K. Webb, And A. S. Wojcik. (1992): Segmental Patterns of Sagittal Spinal Curvatures in Children Screened for Scoliosis: Kyphotic Angulation at the Thoracolumbar Region and the Mortice Joint. Clinical Anatomy. 5,353-371.

7Vi.fi. Cm as (Ed i Research into Spinal Deformities 4 IOS Press. 22

Etiologic Theories of Idiopathic Scoliosis: The Apical Spinal Deformity - Relevance to Surgical Practice R. G. Burwell 1 , R K Pratt1, J. K. Webb1 1

The Centre for Spinal Studies and Surgery1, Queen's Medical Centre, Nottingham Abstract The current successful management of idiopathic scoliosis is an orthopaedic and not a paediatric responsibility. Hence the immediate aim of etiologic research is to improve surgical treatments based on a better understanding of the causation of the deformity. This focuses attention on the pathomechanisms of the spinal and ribcage deformities. The mechanisms of spinal deformity about the apex are unresolved but may be caused by forces created in the anterior spinal column [28]. Some current theories with practical application involve (1) front-back spinal growth mechanisms, (2) rib growth asymmetry and (3) muscles. Conclusions. The application of theory to surgical practice is advanced for concepts of front-back spinal growth asymmetry but rib hump reassertion occurs after surgery and these concepts ignore the ribcage as a possible factor in scoliosis pathogenesis. A theory of ribcage asymmetry involving concave rib overgrowth is beginning to be evaluated surgically. After surgery for IIS and AIS reassertion of the deformity has been shown to involve preoperative spinal and concave rib factors; the larger the concave ribspinal angle the better results at 2-5 year. Muscular factors that may trigger/exacerbate the apical spinal deformity of scoliosis need more research. The concept that AIS pathogenesis involves putative neuromuscular dysfunction that deforms an immature spine is considered likely by several workers.

1. Possible forces in the anterior spinal column creating the spinal deformity The mechanisms of spinal deformity about the scoliosis apex may be caused by forces created in the anterior spinal column producing lordosis, rotation and lateral curvature [28]. Wever et al [28] interpreted the scoliosis deformity as being caused by bone remodelling due to compressive forces in the anterior spinal column driving the apical vertebra out of the midline but minimized by posterior musculoligamentous tissues of the spine causing torque. 2. Possible spinal mechanisms creating the forces of the spinal deformity Possible spinal mechanisms creating the spinal deformity include [5,6]: 1. Front-back spinal growth uncoupling [Erlacher, Somerville, Ponseti, 7]. 2. A fixed lordotic area which rotates to the side under the influence of transverse plane or frontal plane asymmetry [14]. 3. A short spinal cord causing a posterior tether to anterior spinal growth [ 16-18,21,22]. 4. Greater growth of the concave neurocentral synchondrosis [30].

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33

The short spinal cord concept of Roth and Porter is plausible [16-18,21,22] but needs testing critically, perhaps by using MRI to measure the length of the spinal cord and correlating its length with some extraspinal skeletal component such as a limb bone preferably in a longitudinal study [6]. If so established the correlation might be used prognostically. The question would need to be asked: Does the short spinal cord result from melatonin deficiency? [6,13]. These concepts of spinal mechanisms to account for the spinal deformity of scoliosis ignore the ribcage. Since 1836 many workers have published theories linking the ribcage to the cause of scoliosis (Stromeyer, Feiss, Rogers, Roaf, Piggott). In recent years a few workers have focused on the ribcage in relation to the pathogenesis of idiopathic scoliosis [3,4,11,12,15,23,24]. 3. Possible rib mechanisms triggering the spinal deformity Based on Sevastik's thoracospinal theory of the etiopathogenesis of idiopathic scoliosis involving increased growth of concave ribs [23], a 6-year old girl with juvenile idiopathic scoliosis and a right thoracolumbar (RTL) curve was treated by shortening of three ribs on the concavity (each by 2 cm). The preoperative RTL curve was 46 degrees and at three-year follow-up was 21 degrees. Sevastik [23] considers that while concave rib overgrowth triggers the thoracospinal deformity of right thoracic scoliosis simultaneously in three planes, curve progression is thought to result from biomechanical factors [24]; these may include hypokyphosis, gravity and the Hueter-Volkmann effect [25] acting in the frontal and sagittal planes. 4. Spinal and concave rib factors that predict spinal deformity after surgery 4.1 Infantile idiopathic scoliosis (IIS) Pratt et al [19] reported that in IIS treated by Luque trolley and convex epiphsyeodesis, the Cobb angle and the percentage correction of Cobb angle at 5-year follow-up were each predicted by preoperative (1) apical concave right-spinal angle (RSA) and (2) upper-end vertebral tilt. The larger the apical concave RSA and the smaller the upper-end vertebral tilt preoperatively the smaller was the Cobb angle at 5 years. These spinal and concave rib factors (unlike convex) rib factors are independent and suggest that spine and concave rib pathomechanisms are both important in curve progression in IIS after surgery. 4.2 Adolescent idiopathic scoliosis (A1S) Pratt et al [20] reported that in AIS treated by posterior Universal Spine System reassertion of the rib hump (maximal angle of trunk inclination using a Scoliometer) at 2 years follow-up is predicted by ihe preoperative (1) concave 9th rib-spinal angle (RSA) and (2) lumbar spine factors. The larger the RSA the less the rib-hump reassertion. It was suggested that rib hump reassertion was best explained by unwinding of the ribcage

R.G. Bnrwell el ai / The Apical Spinal t)efnrmit\ - Relevance to Surgical Practice

tensioned by surgery rather than through relative anterior spinal overgrowth (crankshaft effect). This unwinding concept implies that hump reassertion during the first 2 years after surgery with USS for AIS does not represent a continuation of the pathomechanisms of the ribcage deformity.

5. Possible neuromuscular dysfunction creating the spinal deformity The possibility that AIS pathogenesis involves undetected neuromuscular dysfunction is considered likely by several workers [1,2,3-5,7-9,13,27,29] but denied by Goldberg [10]. In this connection Edgar [9] writes that neurological dysfunction in idiopathic scoliosis has moved to a centre-stage position, and now needs to be carefully considered. Taylor [26] writes, "The growing vertebral column is extraordinarily sensitive and responsive to the most subtle alterations in neuromuscular control."

6. Possible muscular factors creating the spinal deformity 1. 2. 3. 4. 5. 6.

Muscular factors that may trigger/exacerbate the apical spinal deformity include [4]: Focal dystonia of deep spinal muscles causing the 'fixed lordotic area'. Deep rotator muscle asymmetry (Fidler and Jowett). Intercostal muscles (Roaf, Schmitt). Superficial trunk muscles (Nudelman and Reis). Diaphragm (Ransford). Hip abductor muscles (Karski, This meeting). In connection with trunk muscles, spinal growth, gravity and the Hueter-Volkmann effect may be involved [25].

7. Conclusions 1. The application of theory to surgical practice is advanced for concepts of front-back spinal growth asymmetry but rib hump reassertion occurs after surgery. These concepts ignore the ribcage as a possible factor in the pathogenesis of idiopathic scoliosis. 2. A concept of ribcage asymmetry involving concave rib overgrowth is beginning to be evaluated surgically. 3. After surgical instrumentation for IIS & AIS reassertion of the spinal and ribhump deformity respectively involves factors in the spine and ribcage (concave ribs). The larger the preoperative concave rib-spinal angle the better the results of surgery after 2-5 years. 4. Possible neuromuscular and muscular mechanisms creating/exacerbating the apical spinal deformity of idiopathic scoliosis need more evaluation.

R.G. Burwell et ai / The Apical Spinal Deformity - Relevance to Surgical Practice

35

References 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.

K.M.Bagnall, Debate 1, Adolescent idiopathic scoliosis: Is the cause neuromuscular? The case for. In: Stokes IAF (ed.), In: Research into Spinal Deformities 2, pp 91-93. Amsterdam:IOS Press, 1999. K.M. Bagnall Ligaments and muscles in adolescent idiopathic scoliosis. Spine:State of the Art Reviews 14(2):447-457, 2000. R.G. Burwell et al, Pathogenesis of idiopathic scoliosis: the Nottingham concept. Acta Orthopaedica Belgica 58: Supplement 1, pp 33-58, 1992. R.G. Burwell, P.M. Dangerfield, Pathogenesis and Assessment of Scoliosis. Chapter 19. In: Surgery of the Spine: A combined orthopaedic and neurosurgical approach. Findlay G, Owen R (eds), Volume 1, pp 365-408. Oxford: Blackwell Scientific Publications, 1992. R.G. Burwell, P.H. Dangerfield, Adolescent idiopathic scoliosis: hypotheses of causation. Spine:State of the Art Reviews 14(2):319-333,2000. R.G.Burwell, Comment to "The pathogenesis of idiopathic scoliosis: uncoupled neuro-osseous growth?" European Spine Journal 10(6): 482-487,2001. J. Cheng, Posterior tibial nerve somatosensory cortical evoked potentials in adolescent scoliosis. Spine 23:332-337,1998. J. Dubousset, Les scolioses dites idiopathiques. Definition, pathologic, classification, etiologie. Bulletin Academic Nationale de Medicine 4:699-704,1999. M. Edgar, Neural mechanisms in the etiology of idiopathic scoliosis. Spine: State of the Art Reviews 14(2):459-468, 2000. C.J. Goldberg, Debate 1, Adolescent idiopathic scoliosis:ls the cause neuromuscular? The case against. In:Stokes IAF (ed,). In: Research into Spinal Deformities 2, pp 94-97. Amsterdam:IOS Press, 1999. T.B. Grivas et al., A segmental analysis of thoracic shape in chest radiographs of children. Changes related to spinal level, age, sex, side and significance for lung growth and scoliosis. Journal of Anatomy 178:21-38, 1991. T.B. Grivas et al.,The double rib contour sign (DRCS) in lateral spinal radiographs: aetiologic implications for scoliosis. In, Research into Spinal Deformities 3. A. Tanguy, B. Peuchot (eds.), Amsterdam:IOS Press, 2002. M. Machida, Cause of idiopathic scoliosis. Spine 24(24):2576-2583, 2000. P.A. Millner, R.A.Dickson, Idiopathic scoliosis: biomechanics and biology. European Spine Journal 5:362-373, 1996. G.P. Pal, Mechanism of production of scoliosis; a hypothesis. Spine 16:288-292,1991. R.W. Porter, Idiopathic scoliosis: The relation between the vertebral canal and ertebral bodies. Spine 25(11):1360-1366, 2000. R.W. Porter Can a short spinal cord produce scoliosis? Eur Spine J 10:2-9,2001. R.W. Porter. The pathogenesis of idiopathic scoliosis: uncoupled neuro-osseous growth? European Spine Journal 10(6): 473-481,2001. R.K. Pratt et ai, Luque trolley and convex epiphyseodesis in the treatment of infantile and juvenile idiopathic scoliosis. Spine 24(): 1538-47, 1999. R.K. Pratt et ai, Changes in surface and radiographic deformity after Universal Spine System for right thoracic adolescent idiopathic scoliosis. Spine 26(16): 1778-1787,2001. M. Roth Idiopathic scoliosis caused by a short spinal cord. Acta Radiologica Diagnosis 7:257-271, 1968. M. Roth, Idiopathic scoliosis from the point of view of the neuroradiologist. Neuroradiologist 21:133-138, 1981. J.A.Sevastik, The thoracospinal concept of the etiopathogenesis of idiopathic scoliosis. Spine:State of the Art Reviews 14(2):391-400,2000. J.A.Sevastik, A new concept for the etiopathogenesis of the thoracospinai deformity of idiopathic scoliosis. First Electronic Focus Group, International Federated Body on Scoliosis Etiology (IBSE). European Spine Journal, In Press. I.A.F. Stokes, Hueter-Volkmann effect. Spine:State of the Art Reviews 14(2):349-357,2000. T.K.F. Taylor, The brain stem and adolescent idiopathic scoliosis: a hypothesis. Spine:State of the Art Reviews 14(2):477-481, 2000.

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27. 28. 29. 30.

A.G. Veldhuizen et ai, The aetiology of idiopathic scoliosis:biomechanical and neuromuscular factors. Eur Spine J 9(3): 178-184, 2000. D.J. Wever, et al., A biomechanical analysis of the vertebral and rib deformities in structural scoliosis. European Spine Journal 8(4):252-260, 1999. J.B. Williamson, Postural control. Spine:State of the Art Reviews 14(2):469-476, 2000. A. Yamazaki et ai, Age at closure of the neurocentral cartilage in the thoracic spine. Journal of Pediatric Orthopedics 18:168-172, 1998.

77i.fi. Grivax(Ed) Research into Spinal Deformities 4 IOS Press. 2002

Etiology of the so-called "idiopathic Scoliosis". Biomechanical explanation of spine deformity. Two groups of development of scoliosis. New rehabilitation treatment; possibility of prophylactics Prof. Tomasz Karski MD PhD University Pediatric Orthopaedic and Rehabilitation Department Chod_ki Street 2, PL - 20-093 Lublin /Poland Tel/fax 0048/81 / 741 56 53 -E-mail: [email protected] Abstract. Introduction: Between various etiological factors of idiopathic scoliosis we also studied the biomechanical causes connected with the hip and pelvic regions. At all children with idiopathic scoliosis there is a real or functional abduction contracture of the right hip (sometimes plus flexions- and out-rotation contracture). The right hip abduction contracture is connected with "syndrome of contractures" at newborns and babies. Material:629 children treated in University Pediatric Orthopaedic Department, Lublin/Poland were divided into two groups: *I group of development of scoliosis- 220 children aged from 4 to 10. Real abduction contracture of the right hip 4-6-8 degree, adduction of the left hip 35-40-45 degree. Rotation deformity, both scoliosis (Lumbar L and thoracic Th) at the same time. Progression. **II group of development of scoliosis - 409 children aged from 10-12 to 14. Adduction of the right hip 10-15 even 20 degrees, adduction of the left hip 35-40-45 degree. Lumbar left convex scoliosis, no rotation deformity or small, no thoracic scoliosis, or small, no progression or small. Information about "syndrome of contractures" Clinical symptoms of _syndrome of contractures" were described exactly by Mau and others. At scoliotic patients we see in the region of right hip the following tissues contracted and shortened: *tractus iliotibialis, *fascia lata, * fascias of m.gluteus medius and minimus, *m. sartorius, *m. rectus, * capsules of right hip joint. Clinical research: Since 1980s we added the tests for the adduction of both hips in straight position of the joint to the standard examination of scoliotic patient. Depending on the value of adduction movements of both hips we divided all patients into two above mentioned groups (I and II). Evaluation of present rehabilitation treatment in our material.'Children were divided into three groups depending on range of scoliosis: A. Scoliosis L 5° - 10°, Th 5° - 10°. These children did not perform (wrong!) extension exercises 10 % B. Scoliosis L 15° - 25°, Th 15° - 25°. These children performed (wrong!) extension exercises 30% C. Scoliosis L 25° - 35°or more.Th 25° - 35° or more. Older children. Extension (wrong!) exercises long time (1-2-3 years!) 60 %

Conclusions:I.The so-called idiopathic scoliosis are connected with the right hip real or functional abduction contracture (sometimes plus flexion and out-rotation contracture). 2.There are two groups of development of idiopathic scoliosis. The first group - small children, early rotation deformity, both scoliosis (L and Th),

T. Karski/ Etiolot>\ of the So-called "Idiopathic Scoliosis'

progression. The second group is connected only with the habit of permanent standing "at ease" on the right leg. Older children. L scoliosis, sometimes Th scoliosis. 3. X-ray pictures of spine with pelvis are necessary for proper diagnosis.4. Abduction contracture of the right hip is connected with "syndrome of contractures" of new-boms and babies.5. We see necessity to introduce new stretching-flexion asymmetric exercises and a special sports program for the children endangered with scoliosis. 6. We proved that the "new prophylactics" through "new clinical test" and "new rehabilitation treatment" at school children (5-6-7-8 years old) gives positives results.

1.Introduction Among various etiological factors of idiopathic scoliosis [18, 19, 27, 29, 30, 31, 33, 39, 40, 41], we also studied the biomechanical causes connected to the hip and pelvic regions. We studied their influence on the spine in the active function of both legs (in gait and in stand position). At all children with idiopathic scoliosis there is a "real" or "functional" abduction contracture of the right hip. The functional contracture means limitation of the range of adduction movement in the right hip in comparison to the left hip. Every examination should be performed in straight position of the hip join (Karski 1996, 1997, 1998, 2000, 2001). Very often the abduction contracture is connected to the flexion and the out-rotation contracture of the right hip [16, 20, 23]. The children with the "real" abduction contracture of the right hip constitute the first group of the development of scoliosis. In another group of patients there is only a difference in adduction of both hips ("functional" abduction contracture). These patients constitute the second group of the development of scoliosis. 2."Syndrome of contractures" in newborn and babies - short description The right hip abduction contracture ("structural" - real abduction contracture or "functional" - only a small range of adduction of the right hip) is connected to the "syndrome of contractures" at newborn and babies described by many English, American, Scandinavian, German and Polish authors but especially by Prof. Hans Mau from Tubingen (1979, 1983). Others authors were: Dega, Lloyd-Roberts & Pilcher, Barlow, Hensinger, Howorth, Green & Griffin, Dangerfield and col., Vizkelety, Heikkila. McMaster, Komprda, Karski, Tarczynska & Karski. 3.Clinical information about the "syndrome of contractures" The clinical symptoms of the "syndrome of contractures" according to Prof. Hans Mau ("Siebener Kontrakturen Syndrom ") and others (English, American and Swedish authors) are: A/ the adduction contracture of the left hip (mostly) with the developmental hip dysplasia (sometimes), B/ torticollis, plagiocephaly (mostly left side), C/ feet and knees deformities, D/ infantile scoliosis (it usually disappears by itself - Mau, Green & Griffin, McMaster, Robinson & McMaster, Karski), E/ the abduction contracture of the

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right hip - the cause of the so-called idiopathic scoliosis through the biomechanical influence on pelvis, os sacrum, lumbal and thoracic spine (Karski 1995-2002). At the scoliotic patients we see in the region of the right hip the following tissues contracted and shortened: *tractus iliotibialis, * fascia lata, * fascia of m. gluteus medius, *fascia of m. gluteus minimus, *m. sartorius, *m. rectus, *capsules of right hip joint. Because of these contractures in the region of the right hip the pelvis on the X-ray picture in infants is very often "oblique" [Fig. la, lb, 2a, 2b].

Fig. la

Fig. lb

Angelika D. 12 m. N° 970818 Oblique position of pelvis because of abduction contracture of the right hip. In age of 3 years both scoliosis appeared. Pelvis - view from the front

Angelika D. 12 m. N° 970818 Oblique position of pelvis because of abduction contracture of the right hip. In age of 3 years both scoliosis appeared: lumbar left convex, thoracic right convex. Spine - view from the back

View from the front Fig. 2a, 2b The scheme of normal and oblique pelvis, (a) In normal pelvis the movement of hips is normal and full, (b) In oblique pelvis there is abduction contracture of the right hip. Sometimes adduction contracture of the left hip and congenital dysplasia.

40

T. Karski / Etiology of the So-called "Idiopathic Scoliosis"

4. Material 629 children treated in the University Pediatric Orthopaedic and Rehabilitation Department, Lublin/Poland were divided into two groups. Clinical remarks about the development of scoliosis and information about pathomechanism of the development of both groups (I-st and II-nd) of scoliosis are specified in chapter 7. *I-st group - 220 children, aged from 4 to 10. The real abduction contracture of the right hip was 5-8 degrees or 0 degree; the adduction of the left hip was 35-40-45 degrees, very seldom 50 degrees. At this group we see the beginning of scoliosis already at the age of 2-3-4. It is however invisible in typical clinical examinations! The pathological influence is connected firstly by walking and secondly with stand position "at ease" only on the right leg since first years of life. Lumbar (L) and thoracic (Th) scoliosis appear at the same time; **II-nd group - 409 children aged from 10-12 to 14. The adduction of the right hip was 10-15 even 20-25 degrees, adduction of the left hip was 35-40-45 degrees, seldom 50 degrees (I repeat - examination in straight position of the hip joint). In the beginning one can only see lumbar (or sacro-lumbar, or lumbothoracic) left convex scoliosis. The pathological influence - habit of standing only on the right leg. 5.Confirmation of the presented etiology connected with the "syndrome of contractures" Many authors like Willner (1972), Magoun (1974), Wynne-Davies (1975), Green & Griffin (1982), Dangerfield and col. (1995) describe many deformities of the head and the face, like plagiocephaly, the asymmetry of temporal bone and also the asymmetry in the pelvis (tilt of the left side of pelvis - Gardner, Tylman) and the asymmetry in the whole body at the patients with so-called idiopathic scoliosis. They question what are the origins of these symptoms at the children with idiopathic scoliosis, but through their excellent clinical observation they confirm the biomechanical theory of the etiology of idiopathic scoliosis. 6.How to check the abduction contracture of the right hip? Since 1980s I tried to examine the patients in various positions - laying on the back or laying in prone position but it appeared that the best position to discover the abduction contracture (or lack of adduction) is the stable laying on the side. For clinical examination the pelvis must be stabilised by one hand of the doctor. Then the doctor checks the passive adduction movement of the hips, one at a time. The examined hip can not be in flexion or in in-rotation because in such cases the test is negative. The leg must be in full extension and in zero or out-rotation of the hip joint. [Fig. 3] The difference is measured with goniometer. Depending on the range of adduction of both hips, and other factors described in my book The etiology of the so-called "idiopathic scoliosis" - Karski 2000, there are two groups of the development of scoliosis (Karski and col. 2001).

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Fig. 3 Aleksandra K. 8 y. N° 920907 The examination of adduction of both hips. The child lying stable on one side. Passive checking of adduction. Both hips in straight position. Adduction of the right hip 10 degree, adduction of the left hip 40 degree. Visible scoliosis since two years.

7.The clinical research and some clinical remarks about the development of scoliosis in the group I and in the group II *I-st group of development of scoliosis (220 children - 35%). We found: real abduction contracture (sometimes plus out-rotation and plus flexion contracture) abduction contracture of the right hip was 5-8 degrees or 0 degree; adduction of the left hip was 35-40-45 degrees, very seldom 50 degrees > small children - the first deformation of spine even at the age of 3-4 years. Untill now such types of scoliosis were undetectable, (and they are not infantile scoliosis! [chapter 3, point D]) > pathological influence is caused by gait and additionally by stand position only on the right leg > the first is rotation deformity of the spine > as a result the spine stiffness (even lordotic deformity in thoracic part of spine) > progression. The deformation mechanism is the compensatory twisting movement of pelvis and spine. Such a mechanism was also observed by Prof. Geoffrey Burwell from Nottingham/England [2000] - cited by T. Kotwicki MD from Pozna_/Poland. Prof. Burwell says about the causative twisting movement of the pelvis that provoke the rotation deformity of the spine. In our material we totally confirm this observation at every patient from the I-st group of development of scoliosis. In this I-st group of development of scoliosis the causative factor is the contracture and it must be combined to the gait. Therefore, the causative factor depends on the character of gait and the range of contracture and the range of movement in hips (depends on - "how many movement is missing" and how much of it must be compensated in the region of pelvis, os sacrum and sacro-lumbar and lumbo-thoracic spine). This whole "pathomechanical unit", that means "range of contracture and character of gait", makes scoliosis appear earlier or later, bigger or smaller, with rapid or slower progression. My recent observation (February 2002) is that at every child in the I-st group of development of scoliosis I see very big flexion contracture of both hips but bigger at the right hip. This flexion contracture diminishes the stability in the sacro-lumbar part of spine and by that "makes the development of scoliosis easier". Detection of scoliosis in children from the I-st group at age of 3-4 years is possible with use of X-ray picture - in stand position with symmetrical loading of both legs (knees straight, feet together) and enables us to introduce effective prophylactics [Fig. 4,5].

T. Karski / Etiology of the So-called "Idiopathic Scoliosis

Fig. 4 Komelia G. 8 y. N° 941209 The Ist group of development of scoliosis. Rotation deformity, flat back. Both scoliosis. Tendency to progression. View from the back

Fig. 5 Katarzyna M. 7 y. N° 950721 The I-st group of development of scoliosis. Rotation deformity, flat back with even lordotic deformity in thoracic part of spine. Both scoliosis. View from the back

**II-nd group of development of scoliosis (409 children - 65 %). We found: only limitation of adduction of the right hip (adduction of the right hip was 10-15 even 20-25 degrees, adduction of the left hip was 35-40-45 degrees, seldom 50 degrees) > older children (age 10-12-14) > pathological influence connected with the habit of standing "at ease" on the right leg (long teenage randez-vous with stand position on right leg, visits in museums, long standing rehearsals of choirs, standing in churches, in schools) > lumbar or sacro-lumbar or lumbo-thoracic left convex scoliosis > sometimes development of compensatory right convex thoracic scoliosis > no rotation deformity (or small) > no progression (or small). The treatment is easy: these children only need active sport exercise in order to stop scoliosis effectively. Of course there are patients who can be classified as the patients "on the border" between the I-st and Il-nd group [Fig. 6, 7a, 7b].

Fig. 6 Aneta S. 12 y. N° 830822 The Il-nd group of development of scoliosis. Only lumbar left convex scoliosis. No thoracic scoliosis, no rotation deformity, no progression. View from the back from

Fig. 7a, 7b Zofia G. 7 y. N° 900927 (a) The H-nd group of development of scoliosis. Lumbar left convex scoliosis. "Functional stadium" of scoliosis. Standing on both legs (left picture) - scoliosis. (b) Standing "at ease" on the left leg (right picture) - correction of axis of spine. View the back

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8. The evaluation of the present rehabilitation treatment Children were divided into three groups (at the first meeting with the doctor) depending on the range of scoliosis: D. Scoliosis L 5° - 10°, Th 5° - 10°. Early stage. These children did not perform extension (wrong) exercises - 10% of patients in my whole material. E. Scoliosis L 15° - 25°, Th 15° - 25°. Early stage. These children performed extension (wrong) exercises for short time - 30% of patients in my whole material. F. Scoliosis L 25° - 35° and more, Th 25° - 35° and more. Older children. These children performed extension (wrong) exercises for long periods (1-2-3 years!) - 60% of patients in my whole material.

9. Conclusions 1. The so-called idiopathic scoliosis is connected to the right hip abduction contracture (plus flexion, plus out-rotation contracture [16, 20, 23]) or with the big difference in the adduction movements of both hips. The contracture of the right hip causes asymmetry during walking and provokes compensatory changes in the pelvis and the spine - the rotation deformity, stiffness of spine and spine curves. In all children with scoliosis the first signs of the deformity are visible in pelvis, os sacrum and later in lumbar and thoracic spine (on X-rays). 2. There are two group concerning with the development of idiopathic scoliosis. The first group is connected with the asymmetry while walking and the habit of standing on the right leg. The lumbar and thoracic scolioses appear at the same time, and they are connected with the rotation deformity which causes the "stiffness" of the spine (flat back, disappearing of processi spinosi Th6-Thll - Tomaschewski & Popp, Th7-Th 12 Karski; even lordotic deformity in this part of thoracic spine -Adams, Meyer; and loss of lumbar lordosis - Palacios-Carvajal, Vlach, Rouchal, Neubauer). The second group is only connected to the habit of permanent standing on the right leg. In this second group of patients the first is lumbar, sacro-lumbar or lumbo-thoracic left convex scoliosis. The right convex thoracic scoliosis in this group does not always appear. 3. We found that all scoliotic patients have the habit to stand only on the right leg which is a very important factor for the development of scoliosis. The reason of standing only on the right leg lies in the contracture of the right hip which makes the right leg much more stable and the position itself is more safe and less tiring for children. 4. The abduction contracture of the right hip is connected to the "syndrome of contractures" of new-borns and babies described by many authors. The first information about this syndrome can be the oblique position of the pelvis on X-ray picture made in the baby-period for examination of the hip dysplasia. 5. The X-ray picture for scoliotic patients has to be made with special requirements: * spine with whole pelvis, *in stay and straight position - knee straight, feet together. If the child for the X-ray picture stands on the right leg - the scoliosis is bigger, if the child stands on the left leg the scoliosis is smaller! 6. Even if there is the abduction contracture of the right hip ("real" or "functional" more often)-the following can prevent scoliosis:

---i

T. Ktirxki /Enol(H>\ of the So-called "Idiopathic Scoliosix"

A. the habit of stand position "at ease" on the left leg for ever or on crossed legs. B. the permanent sleeping in foetus position since first years of life, C. the in-rotation gait (together with above noticed factors), D. practicing sports very actively (especially stretching exercises - like Karate, Judo, Taekwon do, Aikido, Kung-fu, ballet, dancing, etc.). Sportsmen and sportswomen do not have scoliosis! 7. We changed the rehabilitation program for scoliotic patients in Poland more that 10 years ago and in Slovakia 4 years ago (Makai, Rehak, Tisovsky). We eliminated the commonly applied earlier in our country wrong!, extension exercises [10, i l , 12, 13. 15, 16, 22,33], 8. We have introduced the new stretching-flexion asymmetric exercises and a special sports program for the children endangered with scoliosis or with already beginning scoliosis. In our Department we prepared the check-out test for prophylactics of scoliosis. 9. The material shows positive examples of "the new therapy". The small curves (Lumbar 5-10-15 degrees and Thoracic 5-10 degrees) can be stopped and in some children cured, the bigger curves (Lumbar 15-20 degrees and Thoracic 15-20 degrees) can be stopped or even diminished. 10. The research conducted in our Department allowed us to create an early and effective new prophylactics program for school children. We proved that the "new prophylactics" through "new clinical test" and "new rehabilitation treatment" at school children (5-6-7-8 years old) or even earlier, give positive results. 11. From the year 2000 we began the new prophylactic program in some towns in Poland, in Slovakia and in Hungary. We are ready to assist in the introduction of this program in other countries. References 1. 2.

3. 4. 5. 6. 7. 8. 9. 10.

11.

Barlow T.G.: Early diagnosis and treatment of congenital dislocation of the hip. J.B.J.S., 962, 44B(2), 292-301 Bunvell G., Dangerfield P. H.,: Spine. Etiology of Adolescent Idiopathic Scoliosis: Current Trends and Relevance to New Treatment Approaches, Volume 14/Number 2, Hanley & Belfus, Inc, May 2000., Philadelphia, str 324 Dangerfield P.M., Dorgan J.C., Scutt D., Gikas G., Taylor J.F.: Stature in Adolescent Idiopathic Scoliosis (AIS).14 Meeting EPOS, Brussels, 5-April 199S, Papers and Abstracts, Page 210. Dega W.: Badania z dziedziny etiologii wrodzonego zwichniecia biodra. Chir. Narz. Ruchu,144, II1932. Gardner A. - personal information Green N.E., Griffin P. P.: Hip dysplasia associated with abduction contracture of the contralateral hip. J.B.J.S.1982,63-A, 1273-1281. Heikkila' E.: Congenital dislocation of the hip in Finland. An epidemiologic analysis of 1035 cases, ActaOrthop. Scandinavica 1984, B.55,125-129. Hensinger R.N.: Congenital dislocation of the hip. Clinical Symp. 1979, 31 Howorth B.: The etiology of the congenital dislocation of the hip, Clin. Orthop., 1977,29, 164-179 Karski T.: Kontrakturen und WachstumsstOmngen im Haft- urtd Beckenbereich in der Atiologie der sogenannten "Jdiopathischen Skoliosen" - biomechanische Uberlegungen, Orthop. Praxis, 3/96, 32:155-160 Karski T.: Biomechanical influence onto the development of the so-called "idiopathic scoliosis" clinical and radiological symptoms of the disorder. Acta Orthopaedica Yugoslavia, 28(1997) 1, 915

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12.

13. 14.

15.

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22. 23.

24. 25. 26. 27. 28. 29. 30.

31. 32.

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Karski T. _Hip abductor contracture as a biomechanical factor in the development of the so-called "idiopathic scoliosis". Explanation of the etiology", Magyar Traumatologia, Ortopedia, Kezsebeszet, Plasztikai Sebeszet, 1998,3,239 - 246 Karski T.: The rehabilitation exercises in the therapy and prophylaxis of the so-called "idiopathic scoliosis", Acta Ortopaedica Yugoslavia, 29, 1998,1, 5-9. Karski T.: in Burwell, Dangerfield - Spine. Etiology of Adolescent Idiopathic Scoliosis: Current Trends and Relevance to New Treatment Approaches, Volume 14/Number 2, Hanley & Belfus, Inc, May 2000., Philadelphia, 324 Karski T.: "Skoliozy tzw. idiopatyczne - przyczyny, rozwj i utrwalanie si_ wady. Profilaktyka i zasady nowej rehabilitacji. The etiology of the so-called idiopathic scoliosis. Progress and fixation of the spine disorders. The prophylaxis and principles of the new rehabilitation treatment", KGM, Lublin, 2000, 1-143 Karski Tomasz, Frelek-Karska Maria, Karski Jacek, Madej Jacek, Kalakucki Jaroslaw 'The syndrome of contractures' at newborns and babies as a cause of dysfunctions of skeletal system and among others of the so-called idiopathic scoliosis. The discovery of the danger of the oncoming scoliosis. Two groups of development of scoliosis. Rules of new prophylactics, Miedzynarodowa Konferencja "Uwarunkowania rozwoju, sprawnosci i zdrowia" International Scientific Conference "Conditions for development of fitness and health" Czestochowa/Poland 10-11 December 2001 Karski T., J. Karski., J. Madej., M. Latalski: "Persdnliche Uberlegungen zur Atiologie der idiopatischen Skoliosen. Praktische Hinweise zur Entdeckung beginnender Skoliosen. Prinzipien der neuen Obungstherapie. MQglichkeiten der Prophylaxe", Ormopadische Praxis 38,2 (2002) 75 - 83 Komprda J.: Difficulties in treatment of congenital dysplasia of the hip in children with the moulded baby syndrome, 10 Meeting of Paediatric Orthopaedics. Abstracts of papers, Bmo, 1988, A20 Lloyd-Roberts G.C., Pilcher M.F. Structural idiopathic scoliosis in Infancy. J.B.J.S., 1965, 47B, 520531 Lowe T., Edgar M., Chir M., Margulies J., Miller N., Raso J., Reinker K., Rivard Ch-H: Current Concepts Review. Etiology of Idiopathic Scoliosis: Current Trends in Research", J.B.J.S., vol. 82-A, No.8, August 2000, 1157 - 1168 Madej J., Karski T., Rehak L. Makai Fr., Ka_akucki J.:"Results of the examinations of school children in Lublin and in Bratislava for the program of prevention of the so-called idiopathic scoliosis". Lecture on the Orthop. Congress in Bratislava, 24 - 27.01.2001 Magoun (1974) in Normelly H. Asymetric rib growth as an aetiological factor in idiopathic scoliosis in adolescent girls, Stockholm 1985,1-103. Malawski S.: "Wlasne zasady leczenia skolioz niskostopniowych w swietle wspolczesnych pogladow na etiologie i patogeneze powstawania skolioz, Chir. Narz. Ruchu i Ortop. Pol.,1994,59,3:189-197 Matussek J. (Oskar-Helene-Heim Berlin) "Information uber Aussenrotation des rechten Beines bei Patientem mit sog. Idiopathischen Skoliosen" (Lecture). Stay in Lublin, Sept. 1997 Mau H.: Powstawanie skoliozy u malych dzieci, w: "Wczesne wykrywanie i zapobieganie progresji bocznych skrzywien kregoslupa" Materialy z Sesji Naukowej PAN, pod red. Prof. W. Degi, Poznan,10-l 1.XI.1980, PZWL, Warszawa 1983, 34-42 Mau H.: Zur Atiopathogenese von Skoliose, Huftdysplasie und Schiefhals im Sauglinsalter. Zeitschrift f. Orthop.1979, 5,601-5. Mau H.:"Die Atiopatogenese der Skoliose", Bttcherei des OrthopSden, Band 33, Enke Verlag Stuttgart 1982,1-110 McMaster M. J. "Infantile idiopathic scoliosis: can it be prevented?" J.B.J.S., 1983,65-8,612-617 Palacios-Carvajal J. (Madrid) "Lumbosacral instability", Lecture on XXII. Cervenansky Days, 24* 25*, January 2002. Bratislava, Slovak Repubic Rehak L."A Device for the Dynamic Correction and Stabilisation of Spinal Deformities", First Interdisciplinary World Congress on Spinal Surgery, Berlin, August 27 - September 1, 2000, Monduzzi Editore, International Proceedings Division, p. 623 - 627 Robinson C. M., McMaster M. J., "Juvenile idiopathic scoliosis. Curve patterns and prognosis in one hundred and nine patients" J. B. J. S., 1996, 78-A, 1140-1148 Skogland L. B., James A., Miller A. "Growth related hormones in idiopathic scoliosis. An endocrine basis for accelerated growth" Acta Orthop. Scandinavica 1980,51, 779-789.

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33.

34. 35. 36. 37. 38. 39. 40. 40. 41.

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Tarczynska M., Karski T., M. Frelek-Karska: "Prenatal conditions for the development of the hip dysplasia in the material of 223 pregnant women, folio wed-up study of the newborn children". EPOS 2000, XIX Meeting of the European Pediatric Orthopaedic Society, Congress Book, Milan, April 5-8.2000, page P8. Tomaschewski R., Popp B.: "Die Funktionelle Behandlung der beginnenden idiopathischen Skoliose". Jahann Ambrosius Earth, Leipzig Heidelberg 1992, 1-96. Tylman D.: Patomechanika bocznych skrzywien kregoslupa, Wydawnictwo Severus, Warszawa, 1995, Seiten 167. Willner (1972) in Normelly H.: Asymetric rib growth as an aetiological factor in idiopathic scoliosis in adolescent girls, Stockholm 1985,1-103. Wynne-Davies (1975) in Normelly H: Asymetric rib growth as an aetiological factor in idiopathic scoliosis in adolescent girls, Stockholm 1985,1-103. Vizkelety T. "Aktuelle Probleme der angeborenen Hiiftluxation und HQftdysplasie". Lecture in Lublin, 29.11.1980, (Author's Manuscript) Vizkelety T. "Le development du toil cotyloidien apres reduction sanglante des luxations congenitales de hanche" Revue Chir. Orthop. Supp. 2, 1975, 61,248 - 250 Vlach O., Rouchal M., Neubauer J. (Brno) "Rtg obraz degenerativni skoliozy", Lecture on XXII. Cervenansky Days, 24* - 25*, January 2002. Bratislava, Slovak Repubic Zarzycki D., Skwarcz A., Tylman D., Pucher A "Naturalna historia bocznych skrzywien kregoslupa", Chir. Narz. Ruchu i Ortop. Polska, 1992, 57, Supp. 1,9-15 Zuk T., Dziak A. "Ortopedia z traumatologie narzadow ruchu", PZWL, Warszawa, 1993, 161-173

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Comparison of body weight and height between normal and scoliotic children Theodores B Grivas, Akrivi Arvaniti, Christina Maziotou, Margarita Manesioti M, Anna Fergadi Scoliosis Clinic, Orthopaedic Department, "Thriasio" General Hospital G. Genimata Avenue, Magula, 19600 Greece E-mail: [email protected] Abstract. Aim: The creation of a database with somatometric parameters (body weight and eight) from school screening children and the comparison of nonscoliotic children with their counterparts suffering of scoliosis to Cobb angle >10° curves. Material and Method: 3631 screened children where divided in 3 groups. The 1st group comprised normal children with 0° angle of trunk inclination, (ATI). The 2nd group comprised children with ATI >1° and < 6°. The third group comprised children with ATI >7° and Cobb angle >10°. The mean/median and standard deviation (± 1 SD) of body weight and height, the body mass index (BMI = weight/height2) and the corrected for the scoliotic curve height were calculated by age. Statistical analysis included descriptives (mean, ± 1 SD, median) and Mann - Whitney non-parametric test. Results: In boys of the 1st and 2nd group 4,25% had obesity (BMI = 30-35), 2,9% severe obesity (BMI = 30-35) and 1,7% morbid obesity (BMI = 40-45)- while 6,4%, 1,9% and 1,3% in girls respectively. In the 3rd group girls, 27,2% were underweight (BMI = 16-20) and 11,3% severely underweight (BMI < 16), while among boys 42% were severely underweight. In the 3rd group there were no obese girls and only 5% obese boys. The comparison of body weight between scoliotic (3rd group) and nonscoliotic children (1st and 2nd group) fails to show any statistical difference. In the 1st and 2nd group, the girls' mean height is greater than that of boys aged 9-12 years but less when boys are 13-18 years old. In the 3rd group a mean of 1,15 cm increase is observed after height correction for the scoliotic curve, in boys and 1,3 cm in girls respectively. The comparison of body height (both uncorrected and corrected) between scoliotic and nonscoliotic children fails to show any statistical difference. Discussion-Conclusions: A variety of findings regarding the stature and weight of AIS children has been published. In this studied Mediterranean sample of the population, the somatometric parameters of height and weight in children with scoliosis, regardless of curve type and site, are not statistically different from their nonscoliotic counterparts.

1. Introduction The somatometric parameters body weight and height are directly associated with the child's growth. Since idiopathic scoliosis is a deformity which develops mainly during growth, the above somatometric parameters are potentially related to this deformity. The progression of growth across the various geographical regions is not similar. Therefore, the study of body weight and height in healthy and scoliotic Mediterranean children may be interesting.

4S

T.R. Gnvas ct til. /Comparison of Rod\ Weight and Height

The aim of this report is the formation of a database with somatometric parameters (body weight and height) from school screening children and the comparison of the same somatometric parameters of non-scoliotic children with these of their counterparts suffering scoliosis with a Cobb angle of >10° curves.

2. Material and Method 2.1 The examined children. 3631 children, 1809 girls and 1822 boys, screened for scoliosis were included in the study. The children were divided into three groups. The 1st group comprised 1592 healthy children, 836 boys and 756 girls, with an 0 angle of trunk inclination, (ATI). The 2nd group comprised 1592 children, 1009 girls and 967 boys, with ATI >1° and < 6 °. The 3rd group comprised 63 scoliotics, 19 boys and 44 girls, with a ATI >7 and a Cobb angle of >10°. Subsequently the children of each group were sorted by age and sex. 2.2 The measurements. The mean body height, and weight with standard deviation (±1SD) and median was calculated for each of the above subgroups of children. The body mass index (BMI) was also measured as body weight divided by height2. The corrected for the curve height of the scoliotics was also calculated using the Bjureand Nachemson 1973,formulam: Logi0y = 0,011x- 0,177 where y is the body height loss in cm and " the Cobb angle of the major scoliotic curve. The stature meter for measurement of the standing height in cm and a scale with 0.5 Kg increments for the body weight was also used. The children were divided in relation to their weight according to Bray and Metropolitan Life Insurance classification as follows: BMI < 16 severe under-weight children, BMI 16-20 under-weight children, BMI 20-25 normal children, BMI 25-30 overweight children, BMI 30-35 obese children, BMI 35-40 severe obese children, BMI 40-45 morbid obese children, BMI > 50 severe morbid obese children. 2.3 The statistical analysis. The techniques used included frequencies, descriptives, (mean, ± SD, Median), Kruskal-Wallis test, Pearson Correlation Coefficient and independent Samples T-test, (SPSS).

3. Results A. Height. In the 1st group, figure 1, the girls' mean height is larger in 9-14 years of age. The boys' mean height is larger in 14 years, and after this age the difference is statistically significant. In the 2nd group, figure 2, the girls' mean height is larger in 10-13 years of age. The boys' mean height is larger following the age of 13 years with a statistically significant difference.

T.B. Grivas et al. / Comparison of Body Weight and Height

49

In the 3rd group, figure 3, the mean corrected height is larger for girls in 12-13 years of age compared with the boys matched for age, but this difference is not statistically significant. Comparing the girls' height in the three groups, it is noticed that scoliotics are taller but not significantly so than the healthy counterparts, figure 4. The same is also noticed for the scoliotic boys, figure 5. An increase of 1,15 cm is noticed in the mean height of the scoliotic boys and 1,3 cm of the scoliotic girls respectively, after the correction of the height for the curve. It is also interesting to note that there is no statistically significant difference for the height (nor for the corrected one) among scoliotics and the healthy groups (1,2) of children by age. B. Weight. It is shown that in the 1st group, figure 6, the girls' mean weight in 9-12 years of age is arithmetically larger than this of boys but not statistically different, while boys' mean weight is statistically larger from the age of 14 years and afterwards. In the 2nd group, figure 7, the girls mean weight, from the age of 8 to 12 years, is arithmetically larger than this of boys but not statistically different, while boys' mean weight from the age of 14 years and afterwards is statistically larger than this of the girls. Comparing the girl's weight in the three groups, figure 8, it is noticed that from the age of 8-12 years, scoliotics are heavier compared to their non-scoliotic counterparts but are thinner after the age of 13. Studying the BMI of the non-scoliotic boys it is shown that 4,25% are obese, 2,9% severe obese and 1,7% morbid obese. Similarly, for the non-scoliotic girls it is shown that 6,4% are obese, 1,9% severe obese and 1,3% morbid obese. The majority of scoliotics have normal BMI and there is no record of obese scoliotic girl in the study population. 4. Discussion Studying the height, it was found that scoliotic girls are taller compared to healthy counterparts, Willner 1974p41. On the contrary Duval-BaupereI8] did not report any height difference between scoliotics and healthy children. Buric et al, 1982t4', reported that scoliotic are 5 cm taller than the healthy girls in the studying population, but there was no difference in the weight between them. Dickson and Sevitt, 1982[7], in Britain and Leong et al, 1982, in south China, reported that AIS girls are taller compared to findings for girls from recent studies. Archer and Dickson, 1985[1], reported that the mean girls height suffering AIS with curves measuring Cobb angle > 15 , were significantly larger from the mean height of girls with curves measuring Cobb angle :£ 15 . Carr et al, 1989I5], found that scoliotics have a loss of height from 0 to 5,3 cm (mean 2,2 cm), when the estimation of height loss is based on the severity of the lateral curve of the spine and the kyphosis /lordosis. The formula they use to estimate the height loss in scoliotics is: CLS + (SSL - SSL normal). They used ISIS for curve assessment. When their measurements were compared to the height loss due to the curve using Bjure - Nachemson' s 1986131,

T.B. Grivas ct al. / Comparison of Body Weight and Hcis>hr

formula, it was found that the height loss was significantly smaller when ISIS was used for curve assessment. Miraloncar-Dusek et al, 1991^16', showed that scoliotic girls presented higher growth spurt (8,1 cm per year) compared to the healthy girls (7,1 cm per year). They showed a similar growth pattern for boys respectively. Nikolopoulos et al 19851' , reported that the scoliotics standing height is significantly increased compared with healthy girls. Goldberg et al 1993[91, found that scoliotic girls are taller when they are younger while there was no difference in adolescence. This findings are alike to these of Nordwall and Willner 1975fl9), namely there is an auxesis in scoliotics height only in younger age. According to Goldberg's findings the increased height observed in younger scoliotic children is due to the early adolescent growth spur of these girls with late commencement of IS. This theory is supported by the fact that the mean menarch age was significantly lower compared with the relevant national mean age. Grivas et al 19991'1', reported no difference of the menarch age for the scoliotics and the non scoliotic counterparts, using Mediterranean school screening population. It has been reported that in AIS boys and girls BMI is normal before the development of scoliosis, Nissinen et al 1993fl8], and it is decreased during the maturation, Shohat et al 198812'1. Cole et al'61 found that AIS girls show an increase in all their anthropometric parameters compared to their normal counterparts except in the thorax, where the lateral thoracic diameter is significantly different from normal. The mean stature growth in the preoperative AIS girls is constant, as is reported elsewhere too. Grivas, 19841'0*, reported that the healthy girls of 12 years of age are at average taller and heavier than their counterparts. Tsanakas et al 1985f 31, using BMI found that in a Greek study population, the obesity percentage for boys is almost constant in all the ages, while in girls it is increased significantly by the age. The same was shown by Bitsioris et al 1995'2' studying a population in Crete island. Mazagrioti et al 1986'15', documenting the national growth patterns, reported that boys show greater growth velocity from the age of 6 to 10,3 years. From the age of 10,3 and then, this pattern is changing and girls present a greater value of this variable of 0,7 cm compared to boys. From 12,3 years of-age when girls have attained their maximum of growth spurt, a gradual decrease in this difference is commencing so that at the age of 13 years boys are taller than girls. They also observed an obesity tendency in both sexes in all ages, which is stronger for girls. Kapetanoset al 20001'3', reported a significant difference in height between scoliotics and non-scoliotics, but he did not take into account the height loss due to the curve. It is reported that thin children are more susceptible to develop scoliosis at a percentage of 9%, while in fat children the percentage is 4% (Smymis et al 1979t22], Kapetanos et al 1986(12J). A variety of findings regarding the stature and weight of AIS children has been published. As it appears in this studied Mediterranean sample of population, the somatometric parameters of height and weight in children with scoliosis, regardless of curve type and site, are not statistically different from their nonscoliotic counterparts. These findings are in accordance to DuvalBeaupere [8] findings. Coldgerg et al 1993[9], and Willner 19751251, reported that stature development is independent from the severity of the curve. Normelli et al 1985'20', found that girls with thoracolumbar and double major curves are taller at menarch compared to girls suffering from right thoracic curves. It must be mentioned that variables as severity, type and site of the curve and the age at diagnosis of scoliosis are not defined in this study population.

T.B. Grivas et al. / Comparison of Bod\ Weight and Height

51

References 1. 2.

3. 4. 5. 6.

7. 8. 9. 10. 11.

12. 13.

14. 15. 16.

17. 18. 19. 20. 21. 22. 23. 24.

Archer IA, Dickson RA, Stature and idiopathic scoliosis, a prospective study. J Bone Joint Surg, 67B, 185-188, 1985. Bitsori M, Nearchou A, Kazmatzi B, Malathraki M, Kolidaki-Spiridaki M, Rebalakis B, Kafatos A, Kounali D, Kalafatis A. Growth and dietary habits of school age children in the region of Sitia. Paediatriki, 58: 326-335, 1995. Bjure J, Nachemson A: Non-treated scoliosis. Clin. Orthop. 93: 44-52, 1973. Buric M, Momcilovic B: Growth pattern and skeletal age in schoolgirls with idiopathic scoliosis. Clin Orthop 170: 238-242, 1982. Carr AJ, Jefferson RJ, Weiss I, Turner-Smith AR. Correction of Body Height in Scoliotic Patients Using ISIS Scanning. Spine 14: 2, 207-209, 1989. Cole AA, Burwell RG, Dangerfield PH, Grivas TB, Webb JK, Moulton A. Adolescent Idiopathic Scoliosis: Anthropometry. In State of the Art Reviews 2000 (STAR), Hanly and Belfus Inc, 210 South 13th Street, State of the Art Review, Etiology of the Adolescent Idiopathic Scoliosis, RG Burwell, PH Dangerfield, TG Lowe, JYMargulies, (eds). Vol 14(2) May 2000. Dickson RA and Sevitt EA Growth and idiopathic scoliosis: a longitudinal cohort study. J Bone Joint Surg. 64-B, 385, 1982. Duval-Baupere G: Pathogenic relationship between scoliosis and growth. In Zorab PA (ed): Proceedings of a Third Symposium London, Churchill Livingstone, 1971 pp. 58-64. Goldberg GJ, Dowling FE, Fogarty EE, Adolescent Idiopathic Scoliosis- Early Menarche, Normal Growth. Spine 18: 5, 529-535, 1993. Grivas TB: " Survey for the lower limbs of early school age children". MD Theses, University of Athens, Greece, 1984. Grivas TB, Samel is P, Pappa AS, Stavlas P, Polyzois D. Menarche in Scoliotic and Nonscoliotic Mediterranean Girls. Is There Any Relation between Menarche and Laterality of Scoliotic Curves? 2000 Meeting of the International Research Society of Spinal Deformities. Clermont, France, 23-26 May 2000, p.7. In: Research into spinal deformities 3, Peuchot B, Tanguy A (Eds), IOS Press, Amsterdam 2001, in press. Kapetanos G, Pournaras J, Christophoridis J, Pacharliotis A, Symeonidis P. Scoliosis in northern Greece. Proceedings of the Northern-Greece Medical Meeting Volume B, 1986. Kapetanos G: School screening in Macedonia, (Northern Greece). In: Grivas TB (ed): School screening for Scoliosis, Athens Paschalides Medical Publications, 2000, ISBN 960-7398-74-2, pp 47-53. Leong JC et al: Linear growth in southern Chinese female patients with adolescent idiopathic scoliosis. Spine 7, 471-475, 1982. Mantzagrioti-Meimarides M, Pandazides N, Doxiades S, Raphael M. "National growth Standards. Height and weight for children and adolescent Greek population". Paediatriki 49: 1-15, 1986. Mira Loncar-Dusek, Marko Pecina, Zivka Prebeg. A longitudinal study of Growth, Velocity and Development of Secontary Gender Characteristics Versus Onset of Idiopathic Scoliosis. Clin Orthop, 270, 278-282, 1991. Nicolopoulos KS, Burwell RG, Webb JK. Stature and its components in Adolescent Idiopathic Scoliosis, J Bone Joint Surg, 67-B: 594-601, 1985. Nissinen M et al: Trunk asymmetry, posture, growth, and risk of scoliosis. A three-year follow-up of Finnish prepubertal school children, Spine 18:8-13,1993. Nordwall A, Willner S, A study of skeletal age and height in girls with idiopathic scoliosis, Clin. Orthop. 110, 6-10, 1975. Normelli H et al : Anthropometric data relating to normal and scoliotic Scandinavian girls. Spine 10:123-126,1985. Shohat M. et al: Growth and ethnicity in scoliosis. Acta Orthop Scand 59: 310-313, 1988. Smyrnis P, Balavanis I, Alexopoulos A, Siderakis G, Gianestras N, School screening for scoliosis in Athens. J Bone Joint Surg, 61-B, 215-217, 1977. Tsanakas JN, Roilides EJ, Hatzimichaei A, Thodis S, Varlanis P, Karpouzas J: The significance of screening in schoolchildren's health care". Paediatriki 49:154-164, 1986. Willner S: A study of growth in girls with adolescent idiopathic structural scoliosis. Clin Orthop 101: 129-135, 1974.

T.H. (rrh'tif el dl. / Comparison of Htxh Weight and Height

25

Willner S: A study of height, weight and menarche in girls with idiopathic structural scoliosis. Ada OrthopScand 46:71-83, 1975.

of boy. Iglrto MgM to tfc» 1i» gn>w

•parim **•*• kngkl mrtwAnt

-f»fr

Figure 1: Comparison of boys and girls height in the Isr group. (Line with blue circle represents boys, with red triangle represents girls).

Figure 4: Comparison of girls' height in the three groups. (Line with blue diamonds represents group 1, with red triangle represents group 2. and with black rectangle represents group 3).

Figure 2: Comparison of boys and girls height in the 2sr group. (Line with blue circle represents boys, with red triangle represents girls).

Figure S: Comparison of boys' height in the three groups. (Line with blue circle represents group I, with red rectangle represents group 2, and with black triangle represents group 3).

Figure 3: Comparison of boys' and girls' corrected height in the 3rd group. (Line with blue circle represents boys, with red triangle represents girls).

Figure 6: Comparison of boys' \ girls' weight in the 1" group, (boys weight is represented by the line with blue diamonds, girls with red triangle respectively).

T.B. Grivas et al. / Comparison of Body Weight and Height

Comparison of boy» \ girls weight in the 2nd group

Figure 7: Comparison of boys' \ girls' weight in the 2 group, (boys weight is represented by the line with blue diamonds, girls with red triangle respectively).

53

Comparison of gire body wvight among UM thrM group*

Figure 8: Comparison of girls' weight among the three groups. (Line with blue diamond represents group 1, with red rectangle represents group 2, and with black triangle represents group 3).

54

Th.B. Gnvas(Ed.i Research into Spinal Deformities 4 IOS /Vrvs. 2<><>2

Evolution of 3D Deformities in Adolescents with Progressive Idiopathic Scoliosis I. Villemure1'3, C.-E Aubin2 3, G. Grimard1J, J. Dansereau2'3, H. Labelle 13 1- Universite de Montreal/2- Ecole Polytechnique de Montreal, POBox 6079, Station Centre-ville, MontrealH3C3A7, Canada 3-Research Center, Ste-Justine Hospital 3175 Cote Ste-Catherine Rd, Montreal, Canada Abstract. The objective of this study was to conduct an intrasubject longitudinal study quantifying the evolution of two- and three-dimensional geometrical scoliotic descriptors. The evolution of regional and local scoliotic descriptors was analyzed between two scoliotic visits on a cohort of 28 adolescents with progressive idiopathic scoliosis. Mean age at the first visit was 12.711.7 years old and averaged time interval between two assessments reached 22.8±10.8 months. Scoliotic descriptors were obtained from three-dimensionally reconstructed spines. The initial thoracic Cobb angle was on average 35.3°±8.4° (range, 14°-54°). The evolution of spinal curvatures and vertebral deformities was assessed statistically in terms of descriptor absolute variations, and of descriptor variations normalized with respect to time and to the increase in Cobb angle. At the thoracic level, vertebral wedging increased with curve severity in a relatively consistent pattern for most scoliotic patients and axial rotation mainly increased towards curve convexity with scoliosis severity. No consistent evolution was associated with the angular orientation of the maximum wedging. Thoracic kyphosis changes (increase and decrease) were observed in important proportions. Results of this study challenge the existence of a typical scoliotic evolution pattern and suggest that the scoliotic evolution is quite variable and patient-specific.

1. Introduction and objectives The development of adolescent idiopathic scoliosis (AIS) has been investigated using geometrical descriptors to quantify curvatures (regional scale) and intrinsic alterations of vertebral and intervertebral tissues (local scale). Evaluation of geometric descriptors is usually mainly reported in cross-sectional intersubject studies comparing configurations of different individuals. Some of these studies investigated 2D and 3D relationships between regional and local scoliotic deformities [1,2,3]. The literature reports that at the thoracic level scoliosis severity is associated with a "coronalization" of the plane of maximum deformity, an increasing vertebral wedging and an axial rotation evolving towards the curve convexity. Notwithstanding the potential individuality involved in scoliotic progression, the literature reports very few longitudinal studies evaluating different phases of progression for the same individual. The objective of this study was to carry out an intra-subject longitudinal study quantifying evolution of 2D and 3D geometrical descriptors in order to provide complementary information on the progression of adolescent idiopathic scoliosis.

/. Villemure et al. /Evolution of 3D Deformities in Adolescents

55

2. Material and Methods 2.1 Evaluation of regional and local descriptors Descriptors were evaluated analytically from 3D reconstructed spines of scoliotic subjects using a multiview radiographic technique based on calibrated PA and lateral X-rays [4]. For each vertebra, six anatomical landmarks were digitized on both X-rays and reconstructed in 3D using the Direct Linear Transform algorithm [4]. Eight additional noncorresponding points on the vertebral body extremities were used within an iterative procedure fitting 3D oriented ellipses of adequate diameters on both vertebral endplates [5]. The regional descriptors included (Fig.l): 1) the frontal Cobb angle in the global postero-anterior (PA) plane of the subject (Cobb); 2) the Cobb angle, confined by the same end vertebrae of the curve, projected in the plane of maximum deformity (CobbMax); 3) the angular orientation of the plane of maximum deformity with respect to the global sagittal plane of the subject (9 Max); 4) the thoracic kyphosis (Kt) measured using the Cobb method to describe the sagittal profile. The local descriptors included (Fig.2): 1) the maximum 3D wedging angle (oo 30), corresponding to the real 3D inclination magnitude (i.e. maximum) between two adjacent ellipses; 2) the angular orientation of the line joining the maximum and the minimum heights of the vertebral body with respect to the local sagittal plane of the vertebra (6 ^D); 3) the vertebral axial rotation (9 z), defined as the angle between the vertebral and global frontal planes when projected in an auxiliary plane perpendicular to the vertebral body axis (viewed from above, clockwise axial rotation is measured as negative).

Fig.l Regional scoliotic descriptors

Fig.2 Local scoliotic descriptors

2.2 Clinical investigation This study involved AIS thoracic curves developed in right thoracic (12 RT) and right thoracic left lumbar (16 RTLL) curve types. Adolescents (27 females; 1 male) were recruited based on a criterion of scoliosis progression defined as a minimum increase of 5°/year of the Cobb angle in the frontal plane (Cobb). Two visits were considered for each subject. Mean age at the first visit reached 12.7±1.7 years old and averaged time interval between two assessments was 22.8±10.8 months. The overall scoliosis severity as measured by the initial thoracic Cobb angle was on average 35.3°± 8.4° (range, 14°-54°). Regional descriptors were evaluated on the thoracic segment while local descriptors were computed on the thoracic apical vertebra. Absolute descriptor variations between two visits (AD for descriptor D) as well as descriptor variations normalized with respect to time (AD/At) and to the increase in scoliosis severity (AD/ACobb) were investigated to characterize the evolution of scoliotic deformities. Subjects were partitioned with respect to the pattern in the absolute variations of the descriptor (AD>0 or AD<0). Correlation analyses of absolute descriptor variations were completed to analyze relationships between the evolution of regional and local deformities, with a significance level set at p=0.05, which was considered adequate to investigate potential trends.

^

/. Villemiire ct ai / Evoluricn i>f 3D Deformities in Adolescents

3. Results Overall, a mean increase in Cobb angle of 16.1°±9.0° (from 35.3°±8.4° to 51.4°±8.5°) was found between two assessments, and translated an average progression of 8.8°±3.4° per year (Table I). The corresponding Cobb angle in the plane of maximum deformity (CobbMax) was slightly higher compared to the Cobb angle in the frontal plane, but resulted in a similar curvature progression (15.9°±9.7°) (Table I). Slightly greater increases were found in the normalized variations of Cobbm.x, with an average yearly progression of 9.2°±5.8°, and a mean increase of 1.05°±0.64° per degree of Cobb progression (Table I). The spinal curves in the plane of maximum deformity (Cobbmax) increased for all subjects (Fig.3). The angular orientation of the plane of maximum deformity 6 Max invariably remained in the right postero-lateral side of the subject (Table I), with this plane mostly evolving towards the frontal plane (in 71% of the subjects) (Fig.3). Corresponding normalized variations indicated an average yearly evolution of 3.0°±4.6° of this plane towards the frontal plane as well as a displacement of 0.42°±0.65° per degree of curve increase (Table I). The mean kyphosis (about 30°) was similar throughout the studied period (Table I), with most subjects having a kyphosis that increased with scoliosis (in 64% of the subjects) (Fig.3). The normalized variations of kyphosis also showed considerable variability, with relatively high standard deviations (Table I). Table 1. Statistics for descriptors and their variations between scoliotic visits. Proportions of subjects (%) as partitioned in positive and negative absolute variations of descriptors AD (e.g. counterclockwise axial rotation 6 z for 18%, and implicitly, clockwise axial rotation 6 z for 82 % of the cases).

Average variations in apical wedging was 5.1°±4.2° (co 30) over two visits (Table I), with increasing trend in 93% of the cases (Fig.3). Corresponding normalized variations indicated a mean yearly increase of 2.6°±2.0°, with a wedging increase of 0.31°±0.24° per degree of curve progression (Table I). Angular orientations 6 ,,30 were consistently located in the right lateral quadrant of the vertebra (Table I), but they showed variable evolutions (Fig.3). Correspondingly, the normalized variations indicated non-negligible variability with relatively high standard deviations (Table I). An average axial rotation of 7.8°±8.4° clockwise was obtained (Table I), indicating that the vertebral body is rotating towards the convexity of the curve. The vertebral axial rotation showed significant aggravating trend in 82% of the cases (Fig.3). This translated in an average clockwise rotation of 5.3°±8.2° per year and a clockwise increase of 0.60°±0.78° per degree of Cobb (Table I).

/. Villemure et al. /Evolution of 3D Deformities in Adolescents

Figure 3. Diagram presenting proportions of subjects (%) as partitioned in positive and negative absolute descriptor variations (e.g. clockwise axial rotation 9 z for 82% of the cases). Table 2. Correlations between absolute variations of regional and local scoliotic descriptors. A(K.)

A(Cobb)

ACCobbftb.)

A()

p = 0.91

p < 0.001

p = 0.02

A(e^,)

p = 0.91

p = 0.66

p = 0.58

p = 0.43

A(60

p = 0.36

p = 0.78

p = 0.75

p = 0.19

Aie.to)

A<6,) p = 0.05 p = 0.90

Statistical correlation (p ^ 0.05) was found for the two combinations relating the absolute variations of Cobb angles to the changes in wedging angle (Table II). None of the relationships involving the sagittal profile A(Kt) were significant, with p values varying between 0.36 and 0.91. A weak statistical correlation was obtained for vertebral axial rotation relative to the wedging angle. Overall, the change in the orientation of the line joining the maximum and minimum vertebral body heights A6 ^D was not statistically correlated with the variations of all regional descriptors, even if a relationship with its regional homologous describing the angular orientation of the SDcurvature A9 Max might have been expected. Relationships of axial rotation with respect to regional descriptors were inconclusive although a potential trend was observed between A9 z and A6 Max4. Discussion At the thoracic level, vertebral alterations in wedging and axial rotation increase for most scoliotic patients, so as to worsen the progression of vertebral body deformities. A decrease in kyphosis tends to shift the plane of maximum deformity towards the frontal plane and hence the considerable variability observed among subjects in the kyphosis evolution could explain part of the discrepancy in the evolution of the plane of maximum deformity. Most scoliotic patients included in this study are undergoing orthopedic treatment and therefore reconstructed spinal geometries do not strictly reflect the natural history of scoliosis. Limits also include accuracy of the analytical evaluation of regional and local scoliotic descriptors. However, magnitudes of these errors remain overall below the corresponding

57

/. Villemni'c ft til. /Evolution of M) Deformities in Adolescents

descriptor absolute variations and consequently do not invalidate the conclusions drawn for the different statistical analyses. Overall, results of this study challenge the existence of a typical scoliotic evolution pattern and suggest that the scoliotic evolution is quite variable and patient-specific. Intra-subject approaches should then be preferred to inter-subject clinical studies when investigating progression patterns and effectiveness of brace or surgical treatments of scoliotic adolescents.

5. Acknowledgements This research project was funded by N.S.E.R.C. (Canada), C.I.H.R. (Canada), and the Foundations of Sainte-Justine Hospital and Ecole Polytechnique.

References 1. 2. 3.

4.

5.

PerdrioUe R, Becchetti S, Vidal J, Lopez P (1993), Mechanical process and growth cartilages, Spine. 18,343-349. Stokes IAF, Bigalow LC, Moreland MS (1987), Three-dimensional spinal curvature in idiopathic scoliosis, J Orthop Res, 5, 102-113. Villemure I, Aubin CE, Dansereau J, Petit Y, Labelle H (1999), A correlation study between spinal curvatures and vertebral and intervertebral deformities in idiopathic scoliosis, Ann Chir. 53, 798-807. Dansereau J, Beauchamp A, de Guise JA, Labelle H (1990), Three-dimensional reconstruction of the spine and the rib cage from stereoradiographic and imaging techniques, Proc. 16th Conf CSMEvol2 ,61-64. Aubin C-E, Dansereau J, Petit Y, Parent F, de Guise JA, Labelle H (1998), Three-dimensional measurement of wedged scoliotic vertebrae and intervertebral disks, Eur Spine J, 7, 59-65.

TH.B. Grivas(EcL) Research into Spinal Deformities 4 IOS Press, 2002

Adolescent idiopathic scoliosis: natural history and prognosis C.J.Goldberg. D.P.Moore. E.E.Fogarty. F.E.Dowling. Children's Research Centre & Orthopaedic Department, Our Lady's Hospital for Sick Children, Crumlin. Dublin 12. Ireland e-mail: [email protected]/fax +353-1-455-0201 Abstract. Retrospective review of the scoliosis database showed adolescent idiopathic scoliosis to be the most common but least significant variety of spinal deformity. Data from 112 girls diagnosed on repeat screening showed the importance of menarche as a date in the natural history. In the whole database, there were 514 aged at least 15 years at last review, 45 boys and 469 girls. Braces were prescribed for a total of 38, mostly during the early part of the period and gradually abandoned without an increase in surgical rate. Progression depended on the age and maturity of the patient as well as the initial Cobb angle. Surgery was recommended for 27% overall. A sub-group with more complete data diagnosed after bracing had been discontinued confirmed the findings.

1. Introduction Adolescent idiopathic scoliosis (AIS) has been intensively studied for many years but conclusions on prognosis and treatment are confused and varied. For over half a century, the sole criterion for recording and analysing scoliosis has been the Cobb angle, which is justifiably the gold standard [2]. However, it does have limitations which need to be acknowledged: most obviously it takes a 3-dimensional deformity, reduces it to 2-dimensions by the radiographic process and then expresses it as a single number (linear or 1-dimensional). There are other aspects to scoliosis, specifically rib hump, trunk asymmetry and imbalance, which are not described by this otherwise useful measure. In addition, while several studies have reported intra- and inter-observer error [ I ] , there are no studies published which investigate the intra-subject variation. Nevertheless, significant change is taken as 5F, although the only justification for this is that it was given by James in 1976 as an estimate for \nter-observer variation |6]. It is not at all evident that such a small change in Cobb angle, even if it could be accurately measured, has relevance to morbidity, mortality or final prognosis. It seems that studies designed to describe the natural history of AIS have, instead, described the natural history of the Cobb angle.

2. Materials and Methods 1. Repeat screening The natural history of scoliosis is, perforce, taken to begin at diagnosis because it is not possible to know what happened before then, how long the deformity had been developing or when it started. A small group from the initial

59

screening programme between the years 1979 and 1990 were identified who had been passed normal on their first examination but diagnosed with AIS on a repeat screening examination in a subsequent year. These were analysed in regard to age, Cobb angle, maturity and outcome. 2. Database overview All patients with a diagnosis of adolescent idiopathic scoliosis were identified and note was taken of age at diagnosis and last review, of Cobb angles on these occasions and of status (whether operated or not). Only those who had passed their fifteenth birthday at last review are included here. 3. Selected sub-group A sub-group with more complete records, presenting since 1990 (after bracing had been discontinued) was extracted for more detailed analysis. This group was studied more closely because, individually, they had been perceived to be more likely to progress, for reason of immaturity or curve size. They do not constitute a group that was specifically selected in advance but, because of the way their history unfolded, their records are more complete. 3. Results 1. Results from repeat screening Of the 55,484 girls examined in the years 1979 - 90 of the school scoliosis screening programme and were passed normal, 24,674 had one or more routine repeat examinations in subsequent years. Of these, 112 (0.45%) had developed AIS (Cobb angle 10°or more) on a later test occasion. Their mean age at first screening examination was 11.6 + 1.3 years and at the time of diagnosis was 13.6+ 1.2 years. Mean age at menarche was 13.12 + 1.02 years, and the first (normal) examination was at a mean of 1.52 + 1.69 years before this, while diagnosis was at a mean of 0.52 + 1.5 years after menarche. Mean Cobb angle at diagnosis was 17.1 ° + 9.2 and at last review was 16.8° + 13.7, thus the majority did not progress significantly. The mean change was a decrease of 0.59_ + 9.04, range an improvement 20° to an increase of 29°. Change in Cobb angle correlated with statistical significance (Pearson's coefficient -0.387, p<0.01) with the time between menarche and diagnosis. Final Cobb angles were greater than 40° in 13 girls, of whom all but 3 had progressed from below that figure under observation. Surgery was carried out on 6 girls, 5.4% of this subgroup and 0.02% of the re-screened group. 2. Total database For AIS there were 514 patients, 45 male and 469 female who were at least 15 years old when last reviewed. Age at diagnosis was 13.8 + 1.56, range 10 - 18.5, and at last review was 17.4 ± 2.56, range 15 - 34.8. Presenting Cobb angle was 30.04° + 17.8, range 10 - 110 and final Cobb angle was 35.77° ± 21.53, range 1 120. Braces were prescribed to 37 children and 1 patient had been braced prior to attending this centre. Surgery for unacceptable deformity was carried out on 16 of the 38 braced patients (42%) and on 122 of the 472 unbraced patients (25.8%) giving an apparent advantage to non-intervention (p=0.037). Overall, 27% underwent surgery. The incidence of surgery associated significantly with Cobb angle at

C.J. Goldberg ct al. /AIS: Natural History and Prognosis

presentation, and with progression (Mann-Whitney, pO.OOl), but not with age at diagnosis. Curve progression significantly correlated with growth rate at the time, (p<0.001) and was greatest in the months before menarche. Those diagnosed after menarche were less likely to experience progression of Cobb angle, although this seemed less true of rib-hump. 3. Selected sub-group The subgroup, presenting after December 1990 who were at least 15 years of age at last review, numbered 212, 21 boys and 191 girls. Age at diagnosis was 14.1 ± 1.48 years, range 10.6 - 18.5, and when last seen was 16.98 ±1.46 years, range 15.05 - 22.5. Mean Cobb angle at diagnosis was 35.36° + 18.4, range 9 - 100, and at last review was 42.05° ±21.95, range 5 - 120. The mean change in Cobb angle was 6.69° ± 11.87, range (11)-55. The distribution of Cobb angle in 10_ increments is given in Table 1, together the numbers progressing by at least 10_, the incidence of surgery and the numbers at last review in the same curve categories. Curve size at diagnosis did not correlate with age at presentation or with the degree of change. However, the amount of progression did correlate positively with age at diagnosis, which is a partial indicator of maturity. Table 2 shows the association between monarchal status at diagnosis and the incidence of progression by at least 10° and of surgery. Monarchal status is not recorded in one girl. The table shows that both significant progression of Cobb angle (at least 10°) and the incidence of surgery (to some extent an expression of cosmesis) are closely associated by the patient's maturity as expressed by monarchal status. Over a mean follow-up time of 2.9 ±1.6 years, increase in height was 4.7 cms + 4.7 from 159 cms ± 7.5 to 163.7 cms ± 6.7. There was a statistically significant correlation between the growth rate and the change in Cobb angle, Pearson's coefficient = 0.409, pO.Ol. 4. Discussion 1. Repeat screening While these results do not precisely identify the initiation of scoliosis, they do show that it did have a start point from a previously normal developmental history. At an average age of 11.6 years, these patients were normal, like the vast majority of their peers. Two years later, at age 13.6, 112 had developed radiologically confirmed idiopathic scoliosis. Their youth at their first examination, coupled with the proximity of diagnosis to menarche, shows the importance of puberty and of the growth spurt in adolescent idiopathic scoliosis. The relevance of menarche is not from its hormonal changes, but from the orientation it gives, permitting the girl's position on her growth trajectory to be determined. That the majority had minor curves and remain untreated to this day further underlines the inherently self-limiting nature of this "deformity" for most patients. 2. Adolescent idiopathic scoliosis - complete database The total group of adolescent idiopathic scoliosis shows a mixed picture and emphasises the relevance for outcome of growth and maturity at presentation. Young immature patients will progress during the growth spurt, their progression potential declining rapidly after peak growth velocity. Those who are already mature at presentation will only rarely progress significantly. This database contains only 2 girls who showed major progression after menarche (from Cobb angles less than 25°

. / AIS: .\iinii'iil Histor\ and Prognosis

Table 1 Curve Size at diagnosis and last review, numbers progressing at least 10°, and the incidence ofsurgery

1° Cobb angle <20° 20°-29° 30°-39°

40 ° - 49 ° 50 ° - 59 ° 60° + Total

N 35 55 47 30 20 25 212

Prog.>90 4(11.4%) 12(21.8%) 15(31.9%) 12 (40%) 7 (35%) 5 (25%) 55 (25.95)

Surgery 1 (2.9%) 7(12.7%) 10(21.3%) 1 1(36.7%) 15(75%) 22 (88%) 66(31.13%)

Last Cobb

32 41 31 32 25 51 212

Progression by 10 ° did not correlate with presenting Cobb angle, X2 = 9.596, df = 5, p=0.088, but the incidence of surgery did:, X 2 = 72.154, df = 5, jxO.OOl. Table 2. The association between menarchal status at diagnosis and the incidence of progression by at least 10° and of surgery.

No prog. Premenarche. Postmenarche Fisher's Exact

44 96 140

Prog.>90 33 17 50 PO.001

No Surgery 45 87 132

Surgery 32 26 58 P=0.01

Total 77 113 190

C.J. Goldberg et al. /AIS: Natural History and Prognosis

to over 40_ and surgery) after passing menarche, and in both cases this was slow albeit relentless. One of the patients was, strictly speaking, a juvenile idiopathic diagnosis, since she presented at age 9 years 2 months and already 3 months postmenarche, an unusual occurrence for which no cause could be found. However, exceptions, no matter how memorable, do not negate the general rule that scoliosis progresses along with growth and development since it is inherently a part of them. 3. Selected sub-group The above observation is born out in greater detail by this group. Menarche is the defining date for girls, but the relevance of menarche is only that it is a known point on the growth velocity curve (about three months after peak growth velocity). All this can be observed without recourse to repeated radiographs, or measuring of Cobb angles. Observation, surface topography and close attention to growth pattern and monarchal status give more information than a radiograph during observation. 5.Conclusion These results can be repeated in any scoliosis centre in the world, regardless of treatment policy. All that is required is that the clinician considers the whole patient, not merely the radiograph. About one quarter will develop a cosmetic deformity and will want it corrected. The remainder will stabilise their scoliosis before this stage and without treatment. Deformity progresses with growth and correlates with growth rate, so is intrinsic to the growth process. Failure to comprehend this, and to correlate radiological and cosmetic change with age, maturity and growth rate has given rise to the confusion that surrounds management and the efficacy of nonoperative treatment. The enthusiastic treatment of mild scoliosis that has long since lost its potential for deterioration will deceive the uncritical and lead to overtreatment, increased costs to patients and to health services and do no good to anyone. References 1. 2. 3. 4. 5. 6.

Carman DL. Browne RH. Birch JG. (1990) Measurement of scoliosis and kyphosis radiographs. J.Bone & Joint Surg. 72(A):328-333. Cobb JR. (1948) Outline for the study of scoliosis. AAOS. 7:261-275. Emans JB. Kaelin A. Bancel P. Hall JE. Miller ME. (1986) The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients. Spine. 11(8):792-801. Goldberg CJ. Dowling FE. Fogarty EE. Moore DP. (1995) School scoliosis screening and the US Preventive Services Task Force. An examination of long-term results. Spine. 20(12): 1368-1374. Goldberg CJ. Moore DP. Fogarty EE. Dowling FE. (2001) Adolescent Idiopathic Scoliosis: the effect of brace treatment on the incidence of surgery. Spine. 26(l):42-47. James JJJP. (1976) Scoliosis. Ed.2. pplO-11. Edinburgh. Churchill Livingstone.

63

77i.fi. GrivaslEd.i Research into Spinal Deformities 4 IOS Preay 2tX>2

Prediction of spinal deformity in scoliosis from geometric torsion Philippe Poncet1, Jacob L. Jaremko1, Janet Ronsky2, James Harder3, Jean Dansereau4, Hubert Labelle5, Ronald F. Zernickei;! J

Dept. of Surgery, University of Calgary, 3330 Hospital Drive, Calgary (Alberta) T2N4NJ; 2Dept. Mechanical and Manufacturing Eng., University of Calgary, 2500 University Drive, Calgary (Alberta) T2N1N4; 3Dept. of Orthopaedic Surgery, Alberta Children's Hospital, 1820 Richmond Road SW, Calgary (Alberta) T2T 5C7 CANADA; 4 Ecole Polytechnique of Montreal, P.O. Box 6079, Station "Centre-ville", Montreal (Quebec) H3C 3A7;''Sainte-Justine Hospital, 3175 Cote SainteCatherine, Montreal (Quebec) H3TIC5 CANADA Abstract. The shape of a curved line that passes through thoracic and lumbar vertebrae is often used to study spinal deformity with measurements in "auxiliary" planes that are not truly three-dimensional (3D). Here we propose a new index, the geometric torsion, which could uniquely describe the spinal deformity. In this study we assessed whether geometric torsion could be effectively used to predict spinal deformity with the aid of multiple linear regression. Anatomical landmarks were obtained from multi-view radiographic reconstruction and used to generate 3D model of the spine and rib cage of 28 patients. Fourier series best fitted to the vertebral centroids approximated the spinal shape. For each patient, spinal deformity indices were computed. Torsion was calculated and 20 derived parameters were recorded. Torsion inputs were used in a multiple linear regression model for prediction of key spinal indices. The primary clinical Cobb angle (mainly thoracic) was predicted well, with r=0.89 using all 20 inputs of torsion or r=0.83 using just two. Torsion was also well related to the orientation of plane of maximal deformity (r=0.87). Torsion was less accurate but still significant in predicting maximal vertebral axial rotation (^=0.77). This preliminary study showed promising results for the use of geometric torsion as an alternative 3D index of spinal deformity.

1. Introduction Scoliosis is a complex deformation of the spine involving local and global curve shape transformations. The underlying deformation mechanisms, however, are not well understood. The shape of a curved line that passes through thoracic and lumbar vertebrae is often used to study spinal deformity with measurements in "auxiliary" planes that are not truly three-dimensional (3D). Because of the 3D nature of scoliosis, 3D description of deformity should be more significant for the understanding and management of scoliosis. According to vector geometry, a line in space has 3D intrinsic properties expressed mathematically as curvature and torsion. These properties can be used to define the 3D characteristics of the curved line that passes through the vertebra. Here we propose a new index, the geometric torsion, which could uniquely describe the spinal deformity. The concept of torsion of a curve is a completely different concept from that of torsion in rigid body kinematics. If mechanical torsion is defined as a rotation

P. Poncet et al. /Prediction of Spinal Deformity in Scoliosis

around a specified axis (e.g., difference in vertebral axial rotation between two specified vertebrae), then geometric torsion is an intrinsic property that measures the amount of deviation of the vertebrae from a single plane. Geometric torsion is a true 3D measurement, as a straight line or any bi-dimensional geometry like a circle or a planar curve have no torsion. Because a normal spine is assumed to lie entirely in the sagittal plane, its representation is a plane curve without torsion, and it would be reasonable to expect that the presence and magnitude of torsion would, therefore, be related to scoliosis severity. In this study we assessed whether geometric torsion could be effectively used to predict spinal deformity with the aid of multiple linear regression. 2. Materials and Method A group of 28 patients (22 females) with adolescent idiopathic scoliosis were recruited at the Alberta Children's Hospital (Calgary, Canada). Patients had a variety of spinal curvatures: 12 had a major right thoracic scoliotic curve, 11 had a major right thoracic-left lumbar curve, 2 had a major left thoracolumbar curve, 2 had a left lumbar curve, and one had a major right lumbar curve. The patients had an average age of 13.3 years (range, 9.5-18.6 years) and a mean maximal spinal Cobb angle of 34° (range, 11-76°). For each patient, personalized 3D reconstructions of scoliotic spines were obtained from a technique developed by Dansereau et al. [1]. The geometric model is built using the direct linear transformation method [2] and applied to six anatomic landmarks per vertebra (superior and inferior bases of both pedicles and endplate centers) digitised on two posteroanterior radiographs views (PA-0° and PA-200). Findings show that the reconstruction accuracy of this technique is 5.6 ±4.5 mm [3]. The 3D location of the centroid for each thoracic and lumbar vertebra was computed as the mean of the four bases of pedicles. By fitting a 3D curve through vertebral centroids using a least square Fourier series method, a mathematical parametric description was obtained for each individual shape of the 28 reconstructed scoliotic spines. Frenet's formulas then were used to calculate the geometric torsion [4]. Torsion was calculated (Frenet formulas) and 20 derived parameters were recorded such as value and location of maximum and minimum of torsion, sign of torsion in the curve, torsion at the curve apex, location of zero of torsion, sum and range of torsion from end vertebra. For each patient, conventional spinal deformity indices were obtained for correlation with torsion indexes. The apex location for each curve was defined as the most laterally-deviated vertebra on PA projection of spinal curve and was recorded as an integer from 1 (Tl) to 17 (L5). The clinical Cobb angle measured on radiographic film and the strongly correlated computer Cobb angle [5], defined as the frontal-plane angle between the two lines perpendicular to the curve inflection points in each spinal curve, were evaluated. The magnitude of vertebral axial rotation was calculated at each level using the method of Stokes et al. [6] and was based on measuring the position of the vertebral pedicles relative to the vertebral body centre, corrected for the antero-posterior distance from pedicles to vertebral body centre. The reported average measurement error of the method was 3° [7]. The maximum value of vertebral rotation within each curve was extracted and the vertebral level at which this occurred was noted. The orientation of the plane of maximal curvature was calculated by a computer program that sought the plane in

65

66

P. Ponce! a ai. /Prediction nf Spinal Deformity in Scolioxis

which the computer Cobb angle was maximum [6]. This index was used to describe the rotation of the spine. Torsion inputs were used in a multiple linear regression model for prediction of key spinal indices. One by one each output variable (Cobb angle, vertebral axial rotation, orientation of the plane of maximal curvature) was related to the weighted linear combination of input predictor variables (torsion indices), with weights calculated to give the least squared error between the estimated and actual output. The regression was carried out in a stepwise logistic manner which tests all input indices one at a time, adding an index to the model if its contribution is significant (p<0.05) and removing any indices whose contributions become non-significant (p>0.10). For each combination of input variables used, multiple least-squares linear regression was used to generate the best-fit line to the training set, and the line was used to predict the values of each output variables. 3. Results and Discussion The primary clinical Cobb angle (mainly thoracic) was predicted well, with r =0.89 using all 20 inputs of torsion. Using stepwise logistic regression, it was found that just two variables describing torsion (maximal value and range of torsion in curve) could be used to predict the thoracic Cobb angle, with r = 0.83 (Figure 1). Multiple regression analysis showed that addition of more input variables to models generally had little effect on correlations. Correlations were not as good when predicting the magnitude-only, r = 0.60. This is because the torsion model is predicting the direction of the curve accurately, increasing r. Correlations between the 20 torsion inputs and the orientation of plane of maximal deformity were good (r = 0.87). As shown in Figure 2, clearly torsion is well related to the 3D plane of maximal deformity perhaps due to the fact that the orientation of this plane is a "quasi-3D" measurement since it is based on lateral and sagittal curvature of the spine. Torsion was less accurate but still significant in predicting maximal vertebral axial rotation (r = 0.77).

80

ACTUAL Thoracic Cobb Angle <*)

Figure 1: Actual vs. predicted thoracic Cobb angle.

100

P. Poncet et al. /Prediction of Spinal Deformity in Scoliosis

y = 0.9208X RA2 = 0.6262

(I

20

40

60

80

100

120

140

160

ACTUAL OPMD (°)

Figure 2: Actual vs. predicted Orientation of Plane of Maximal Deformity.

4. Conclusion This preliminary study showed promising results for the use of geometric torsion as an alternative 3D index of spinal deformity. Future work will focus on study of more patients including subgroups of patients, and use of an artificial neural network, a high-order non-linear system, to improve correlations and study the reliability of geometric torsion as an accurate marker of scoliosis progression. 5. Acknowledgements The authors are grateful to the Alberta Children's Hospital Department of Radiology for their collaboration in this project (I. Plester, N. Gee and S. Stefanyshyn). The authors also thank the Fraternal Order of Eagle's, the Hospital for Sick Children Foundation and the Arthritis Society for their financial support. References

6.

J. Dansereau et al., Three-dimensional reconstruction of the spine and the rib cage from stereoradiographic and imaging techniques. In Proceedings of the 16th Conference of Canadian Society of Mechanical Engineering, Toronto, Canada, 2,61-64,1990. G.T. Marzan. Rational design for close-range photogrammetry, Ph.D. thesis. Department of Civil Engineering, University of Illinois at Urbana-Champaign, USA, 1976. C.-E. Aubin et al, Morphometric evaluations of personalized 3D reconstructions and geometric models of the human spine, Medical & Biological Engineering & Computing35 (1997)611-618. M.M. Lipschutz, Schaum's outline of theory and problems of differential geometry, Fourteenth Edition, New York: McGraw-Hill, 1969, pp. 61-79. Stokes et al., Three-dimensionalspinal curvature in idiopathic scoliosis, Journal of Orthopedic Research 5 (1987) 102-13. I.A.F. Stokes, Axial rotation component of thoracic scoliosis, Journal of Orthopedic Research 7 (1989) 702-708. Labelle et al., Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages, European Spine Journal 4 (1995) 88-94.

67

Th.B. C.nvastEd.) Rcsiitrc/i into Spinal Deforminc* 4

The natural history of early onset scoliosis C.J.Goldberg. D.P.Moore. E.E.Fogarty. F.E.Dowling. Children's Research Centre & Orthopaedic Department, Our Lady's Hospital for Sick Children, Crumlin. Dublin 72. Ireland e-mail: [email protected]/fax + 353-1-455-0201 Abstract A retrospective analysis of the natural history and treatment outcome of scoliosis, both idiopathic and syndromic, presenting before age 10 years was undertaken. The pattern was generally one of relentless progression, with little discernible benefit from orthotic treatment and surgical correction as the outcome for the majority. This result makes imperative a properly constructed study on the evolution and long-term outcome of this less common but more significant type of spinal deformity.

1. Introduction Scoliosis presenting before age 10 years, whatever the classification, has potentially significant consequences for morbidity and mortality, yet is discussed less than the more benign adolescent varieties. It is a smaller but more varied group, including as it does both juvenile and infantile scoliosis as well as the syndromic deformities where there is another medical condition to be taken into account. The wide age-span and very different presentation and patient type makes generalisation of natural history patterns and treatment outcomes difficult, yet narrowing into smaller sub-groups leaves numbers too small for valid general conclusions to be drawn. This study examines first the natural history of this group as a whole, allowing the differences that may derive from precise aetiology and treatment regime to emerge, rather than presuming ab initio that they will make a difference. 2. Materials and Methods Patients with non-congenital scoliosis attending the spinal deformity clinics at this centre and who presented before age 10 years and were at least 15 years old when last seen were identified. Cobb angle evolution and the incidence of nonoperative treatment and of surgery were analysed. 3. Results There were 132 such patients identified, 49 male and 83 female, who were at least 15 years old when last reviewed clinically. The presenting curve for boys had a mean of 35.22° ± 17.92 and for girls 31.45 ° ± 20.63, no statistical difference. At the end of follow-up, at a mean age of 18.5 years for boys and 18.2 for girls, significant progression of Cobb angle had occurred. Boys now had a mean of 63.19° ± 25.51 and girls, 49.4 ° ± 27.16. This is statistically significant, p<0.01. Surgery had been performed in 33 of 49 boys and 53 of 83 girls, not significantly different proportions.

C.J. Goldberg et at. / The Natural History of Early Onset Scoliosis

Non-operative treatment consisted of spinal jacket when patients were young, under the age of 5 years approximately, although precise indications varied individually. The Boston brace was the preferred non-operative orthosis for older children in whom progression had been documented. One or both of these modalities was prescribed for 51 patients, of whom 38 went on to surgery, while 48 of the remaining 81 underwent surgery without prior non-operative treatment. The difference in proportions is not statistically significant (p=0.092). However, age at surgery was 9.4 years ± 4.67 for the un-braced group and 11.5 years + 3.95 for the braced group, which is statistically significant (p=0.032) suggesting some benefit from orthotic treatment. When the three groups are looked at separately for treatment outcome and age at surgery, it is found that 6 of 11 without conservative treatment for infantile scoliosis and 13 of 15 who had had plaster-jacket or brace had surgery, and this is not statistically significant (p=0.095). Age at surgery was 4.5 for the untreated and 9.1 for the treated, which is statistically significant (p=0.025). For the juvenile idiopathic group, 14 of 25 unbraced and 17 of 22 braced patients had surgery (p=0.217, NS) and there was no difference in age at surgery (12.8 ±3.1 years for the untreated and 13.3 + 1.9, p=0.586 NS, for the treated.). For patients with underlying conditions, secondary or syndromic scoliosis, 28 of 45 untreated had surgery and 8 of 14 treated did so (p=0.762, NS). Age at surgery, 8.7 years ± 4.5 for untreated and 11.4 + 3.8 showed no advantage to the braced group. 4. Discussion Early onset scoliosis is a less common problem than the adolescent forms, but more significant since it carries the risk of cardio-pulmonary compromise that is absent in the later presenting varieties [1]. The results reported here suggest that the natural history is one of relentless progression for the majority with surgery as the probable end-point, although there are some striking exceptions. It was not possible to demonstrate an advantage to bracing in terms of reduction in surgery, and the apparent delay of this intervention in the case of the infantile idiopathic group, welcome though it is, may well be merely a manifestation of the difference between benign and malignant progressive varieties of the deformity. Experience at this centre has shown that adolescents with idiopathic scoliosis can be managed safely and without increased surgery rates by observation only, with surgery for those whose deformity is a cosmetic problem [2]. However, with the present group, the stakes are higher and the risks (respiratory compromise with its consequent increase in morbidity and mortality) correspondingly greater. For this reason, it would be premature to call for an abandonment of current practice, but a far more critical appraisal of results is called for. 5. Conclusion Because spinal deformity with onset in childhood has such a sinister prognosis, detailed study of this field is long overdue. Since all classifications seem to follow a broadly similar course, whether treated non-operatively or not, initial investigations can take advantage of the larger numbers derived from combining groups, while being always conscious of the part played by age, growth history and

69

')

C.J. Goldberg et ai / The Natural Histor\ of Earl\ Onset Scoliosis

underlying health status. Adequate documentation of the natural history, not merely of the Cobb angle, should be undertaken as a long-term project without delay. References 1. 2.

Branthwaite MA. (1986) Cardiorespiratory consequences of unfused idiopathic scoliosis. BrJ.Dis.Chest 80:360-369. Goldberg CJ. Moore DP. Fogarty EE. Dowling FE. (2001) Adolescent Idiopathic Scoliosis: the effect of brace treatment on the incidence of surgery. Spine. 26( 1 ):42-47.

Th.B. Grivas (Ed.) Research into Spinal Deformities 4 IOS Press, 2002

The incidence of idiopathic scoliosis in Greece Analysis of domestic school screening programs Theodores B Grivas, Konstantinos Koukos, Urania I Koukou, Christina Maziotou, Basilios D Polyzois Scoliosis Clinic, Orthopaedic Department, "Thriasio " General Hospital G. Genimata Avenue, Magula, 19600 Greece E-mail: [email protected] Abstract: Introduction. The aim of the study is the documentation of the national incidence of idiopathic scoliosis (IS) based on the School Screening programs performed at the various geographical departments of the country, and the estimation of the probable number of children who will need to be conservatively or surgically treated. Material - Methods: During the years 1975 - 1999, 17 School Screening programs were performed in Greece and their results were analyzed and published in the book " School Screening in Greece". These studies had in common the children age distribution, the clinical examination, the radiological definition of IS when the Cobb - angle was S 5° or > 10° after SRS. The standing forward bending test was used. An Orthopaedic surgeon always participated in the scientific screening team. 215899 children aged 5.5 - 15 years were screened. When there was suspicion of scoliosis, the child was further assessed radiolographically (standing postero - anterior spinal radiographs), for Cobb angle appraisal. Results: In 130689 screened children, scoliosis was considered when the consequent radiological assessment revealed Cobb angle of > 10°, (a), and in 85210 children when it revealed Cobb angle of 2 5° respectively, (b). In (a) studies the scoliosis incidence was 2.9% (range 1.1 - 5.7%), and (b) 4.9% (range 2.7 - 9.5%) respectively. The right thoracic curves dominated in both (a) and (b) studies and thoraco - lumbar, lumbar and double curves followed. Among 7965 scoliotics out of the total sample of 215899 children, 4.5% were conservatively treated with the use of a brace, and only 0.19% was treated surgically. Conclusions: From data of 1998 national census, the population of children aged 8 to 14 years old was approximately 751000. With the above mentioned datum and with a national mean scoliosis incidence of 2.9%, (Cobb angle > 10°), 21781 children will be found with scoliosis. 980 will need conservative treatment using a brace while 41 children will need surgical treatment.

1.

Introduction

The importance of preventive medicine especially in children and adolescents is widely recognized. School screening is still the best and more effective method for the prevention of severe scoliosis deformities. School screening has been performed at various geographical departments of Greece. In this report the results of 17 School Screening programs are presented. The aim is to define the national scoliosis incidence, as well as the number of children who will need conservative or surgical treatment.

71

T.K. Gri\'os el til. /'The Incidence ofIdiopathic Scoliosis in Greece

2.

Material - Methods

The geography of the screening programs. From 1975 to 1999, 17 School screening programs were performed in various geographical departments of Greece. The regions where these programs were performed are more specifically mentioned, namely the area of Thriasion Pedion at the prefecture of Attika, the cities of Athens, of Patra in Peloponissos, of Thessaloniki in Macedonia, of Xanthi in Thracki, the Evia, Chios, Mitilini, Samos, Crete and the Aegean sea Islands, the Ionian Islands, the prefecture of Larissa at the geographical department of Thessalia, and the geographical departments of Epirus, Aitoloacamania and Hemathia. The regions that where mentioned before are presented in Table I, as well as the total number of children who where participated in the School screening programs. Table I: Blue circles shows the regions were school screening programs were performed, as well as the total number (n) of participated children. The percentage of scoliosis is reported in parenthesis. Scoliosis was defined when Cobb angle > 5° for the SS2IO examined children in some school screening programs. More recently and according to SRS, scoliosis is defined when the Cobb angle of a lateral spinal curvature is > 10°.

Athens n=3494 (5.7%, Cobb>10°), Evia n=9537 (9.5%, Cobb>5°), Chios n=4206 (3.6%, Cobb>5°), Mitilini n=5380 (4.1%, Cobb>5°), Samos n=2700 (5.46%, Cobb>10°), Thessalia n=38044 (1.1%, Cobb>10°), Larissa n=22148 (2.7%, Cobb>58), Epirus n=21415 (3.2%, Cobb>10°), Aitoloakarnania n=16743 (1.7%, Cobb>10°), Ionia Islands n=6699 (1.1%, Cobb>10°), Patra n=10000 (2%, Cobb>10°), Thessaloniki n=7658 (6.%%, Cobb>5°), Hemathia n=12490 (7.12%, Cobb>5°), Xanthi n=26612 (2.7%, Cobb>5°), Crete n=21220 (1.7%, Cobb>10°), "St Sofia" Hospital - Athens n=3922 (2%, Cobb>10°), Attica Thriasio Pedio n=3631, (2.9%, Cobb>10°).

T.B. Grivas et al. /The Incidence of Idiopathic Scoliosis in Greece

The examination team of each School screening program comprised of Orthopaedic Surgeons, Physical Therapists and Health Visitors. The leading persons of the examination team are the Orthopaedic Surgeons. The children. 215899, (107226 boys and 108673 girls), aged 5.5 to 15 years old were included in the study. The procedure of the clinical and radiological examination was common in all School Screening programs. The assessment methods. As a rule, the forward bending test (FBT) was used. The FBT was performed as follows: The children were instructed to bend forward, standing with feet together, knees straight and arms dependent and held with fingers and palms in opposition. In the School Screening program of Samos, Patra and Thriasion Pedion, a scoliometer was also used. The readings from the prominence of the back in the thoracic, thoracolumbar and lumbar region were analyzed. The radiographical evaluation, using the Cobb angle, was performed when needed. Definition of scoliosis. Traditionally scoliosis was defined when a lateral spinal curvature measured a Cobb angle of > 5° on a posteroanterior radiograph. This was applied for the 85210 examined children in some school screening programs. More recently and according to SRS, scoliosis is defined when the Cobb angle of a lateral spinal curvature is > 10°. This convention was applied for 130689 examined children. Publicity. All the Greek school screening programs were analyzed and the findings were published, among other chapters, in a 272 pages book, under the title: "School screening in Greece", Athens, Paschalidis Medical Publications, 2000, ISBN 960-7398-74-2. 3.

Results

In 130689 children scoliosis was counted when the Cobb angle was > 10° group (a), and in 85210 children when the Cobb angle was > 5° - group b. After 1986 under the guidelines of SRS, patients were considered scoliotic only when the Cobb angle was > 10°. In group (a) scoliosis was observed at a percentage of 2.9% (range 1.1-5.7%), while in group (b) 4.9% (range 2.7-9.5%) respectively. Regarding the scoliotic curve location, thoracic curves dominated in both (a) and (b) studies and thoracolumbar, lumbar and double curves followed in frequency. In Evia, Chios, Mitilini, Epirus, Thessaloniki and "Thriasion" the girls outnumbered the boys. The highest scoliosis percentage was observed in Evia, Samos and Thessaloniki. From 215899 children, 7965 were found to be scoliotic. From these, 4.5% (358 children) were treated conservatively with braces, while only 0.19% (15 children) underwent surgery. Approximately 90% of the referred children reported for examination at hospital. 4.

Discussion

This study presents the idiopathic scoliosis incidence in Greece, analyzing the data from 17 domestic School Screening programs. From data of the 1998 national census, the children population aged 8 to 14 years old numbered 751000. With the above - mentioned datum and with a national mean scoliosis incidence of 2.9%, (Cobb angle of > 10°), 21781 children will be diagnosed with idiopathic scoliosis.

4

T.B. Grivas a al. / The Incidence of Idiopathic Scoliosis in Greece

According to Stuart & Weinstein (2002) the treatment indications for Idiopathic Scoliosis are given in Table II. The treatment of each patient must be individualized, taking into consideration the probability of progression based on curve magnitude, skeletal maturity, sexual maturity, and age. Following these widely accepted treatment indications, 980 (4.04%) of our scoliotics will need conservative treatment using a brace while 41 (1.88%) children will need surgery. This incidence of patients requiring treatment is close to that reported by Stuart L. Weinstein, in Department of Orthopaedic Surgery at University of Iowa Hospitals and Clinics that is 1.0% for females and 0.1% for males. Table II: Treatment indications for Idiopathic Scoliosis in skeletal immature people

<19° 20 - 29° Greater than or =30°

Initial curvature (skeletally immature) Progression of at least 10° with progression to a curve of greater than or equal to 25° Progression of at least 5° No progression documentation needed

Similar studies from USA, Australia, Japan and Europe reporting the national or regional percentages of IS are briefly mentioned. At LA, California (1975) the incidence was stated as 13.6%. In 1982, Lonstein et al reviewed the experience in Minnesota during an 8-year period, with approximately 250000 children screened per year. The incidence of scoliosis was 1.25%. In China, using a combination of the forward bending test, Moire topography, and radiography, the incidence of scoliosis of > 10° was 1.04%. Rogala et al reported the findings of school screening of 26947 Canadian children from 138 schools. They found 1231 students with structural scoliosis and 48 with nonstructural scoliosis, with an incidence of 4.7%. The incidence of idiopathic scoliosis of > 10° was 2%. The incidence of idiopathic scoliosis of > 10° in a screening study involving 21333 Japanese children was 1.75%. Finally, the incidence of idiopathic scoliosis reported around the world ranges from 1% to 12%, although the incidence of the deformity with Cobb angle of > 10°, resulting from screening programs, is approximately 2%. References 1. 2. 3. 4. 5. 6.

Brooks HL, Azen SP, Gerberg E, Brooks R, Chan L: Scoliosis: A Prospective Epidemiological Study. J Bone Joint Surg 57A: 968-972,1975. Chan A, Molier J, Vimpani G, Paterson D, Southwood R, Sutherland: The case of scoliosis screening in Australian adolescents. Med J Austl45: 379-383, 1986. Cronis S, Gleeson AW: Orthopedic screening of children in Delaware. Phys Ther 54:10801083, 1974. Korovesis PG: Observations made during school screening for scoliosis in Greece. Spine 23 (17): 1924, 1998. Koukourakis I, Giakourakis G, Kouvidis G, Kivernitakis E, Blazos J, and Koukourakis M: Screening school children for scoliosis on the island of Crete. J. Spinal Disord. 10(6): 527531, 1997. Liu, Shang-li and Huang, Dong-Sheng: Scoliosis in China: A General Review. Clinical Orthopaedics and Related Research 323: 113-118,1996.

T.B. Grivas el al. /The Incidence of Idiopaihic Scoliosis in Greece

7. 8. 9.

10. 11. 12.

13.

Lonstein JE, Bjorklund S, and Wanminger MH, Nelson RP: Voluntary school screening for scoliosis in Minnesota. J Bone Joint Surg 64A: 481-488, 1982. Lonstein JE: Screening for spinal deformities in Minnesota schools. Clinical Orthopaedics and Related Research 126:33-42, 1977. Palmisani M, Bettini N, Gargiulo G, Nardi Y, Rizqualloh F, Cosco R, Savini R: The epidemiology of idiopathic scoliosis in the city of Bologna: A three year review of positive cases. Chir Organi Mov 75:353-360,1990. Rogala, EJ, Drummond DS, Gurr J: Scolosis: Incidence and natural history. J Bone Joint Surg 60A: 173-176, 1978. Smyrnis P, Valavanis I, Alexopoulos A, Siderakis G, Giannestras NI: School Screening for Scoliosis in Athens. J Bone Joint Surg 61B: 215,1979. Soucacos PN, Soucacos PK, Zacharis KC, Beris AE, Xenakis TA: School Screening for scoliosis: a prospective epidemiological study in northwestern and central Greece. J Bone Joint Surg 79A: 1498-1503,1997. Zhang GB, Li ZR, Wei XR, Li ZS, Cui QL: Application of Moire topography in school screening for scoliosis. J Chinese Surg 25:387-389,1987.

75

77;. fl. Gri\-as(Ed.i Research nun Spinal Deformities 4

School Screening in the heavily industrialized area Is there any role of industrial environmental factors in Idiopathic Scoliosis prevalence? TB Grivas, P Samelis, BD Polyzois, B Giourelis, D Polyzois Scoliosis Clinic, Orthopaedic Department, "Thriasio " General Hospital G. Genimata Avenue, Magula, 19600 Greece E-mail: [email protected] Abstract. Introduction: School-screening programs contributed greatly to the study of idiopathic scoliosis (IS) prevalence. A similar program confined to a highly industrialized area is being performed in our Department. Thus the comparison of the findings of IS prevalence of this program with those of programs performed in non-industrialized areas of the same country could imply the significance of special industrial environmental factors on IS aetiology. Materials and Methods: 3039 schoolchildren (1506 boys, 1533 girls), aged 5,5 to 17,5 years, have been screened for IS. These children comprise 20% of a total population of 20000 schoolchildren, who live in the region. The detection of the scoliotic children was attained utilizing the criterion of the angle of trunk inclination (ATI). The Prujis scoliometer was used to assess ATI. A cut off point of > 7° ATI was used as a criterion for children's referral to hospital. 262 (8,6%) were referred for further evaluation, whereas 118 (3,9%) among these children underwent radiological examination. Results: 90 children were found to have a Cobb angle of > 10° at their standing PA spinal radiographs (2,9 % of the screened population). A Cobb angle of 10° -20° was found in 74 (2,4%) children. Sixteen (0,5%) children, who had scoliotic curves with a Cobb angle of £20°, underwent conservative treatment by means of spinal orthosis. Relatively to their location on the vertebral column, 20% of the scoliotic curves were thoracic, 26,7% thoracolumbar, 20% lumbar, 24,4% double and 8,9% miscellaneous. Discussion: The screened area represents a place of particular interest because it experienced considerable environmental pollution during the past decades without any improvement of the available Health Services. A quite diverse population in relation to its occupation and its origin inhabits this area as well. The scoliosis incidence found in this area is similar to the incidence observed (2,9%) at other non-industrialized geographical departments of this country (2,6%). This implies that industrial environmental factors probably do not significantly influence the prevalence of AIS.

1. Materials and Methods From 17/1/1997 to 25/1/1999, during School screening for Scoliosis performed by the Orthopaedic Department of the Thriasio General Hospital of Elefsina in the region of Thriasio Pedio, 3039 children (1506 boys, 1533 girls), of ages between 5,5 to 17,5 years were examined. The total population of the pupils in the aforementioned area counts approximately 20000 children, which attend Elementary and High School.

T.B. Grivas et al. /School Screening in the Heavily Industrialized Area

77

This School-screening Program has been carefully organized, which enabled the examiners' team to rapidly obtain the maximal amount of possible information about the examined population. The Adam's Bending Test was performed in standing and sitting position and the amount of trunk rotation was assessed using the Pruijs scoliometer. The finding of Angle of Trunk Rotation (ATR) or Axial Trunk Inclination (ATI) of > 7° at any level of the lumbar, thoracolumbar or thoracic part during forward bending of the trunk, in a standing and sitting position, was used as a Pass-Fail criterion (or Cut Off Point) for the referral of the children for radiological examination [1,2]. Two hundred and sixty two pupils were referred to the hospital for further evaluation, 118 of which underwent radiological examination. This number represents 3,9 % of the examined population. Scoliosis was measured by the Cobb method [3]. 2. Results A summary of the successive steps in detecting and treating the scoliotic children after this school-screening program is presented in Table 1. One hundred and eighteen children underwent radiological examination of their whole vertebral column and chest (posteroanterior and profile standing radiograph). A Cobb Angle of > 10° was found in 90 children. This implies that the prevalence of scoliosis detected by school screening at Thriasio Pedio arises to 2,9 % of the examined population. The majority of the scoliotic children are girls, or 2 % of the examined pupils (boys: 0,9 %). The higher ratio of scoliotic girls is observed in all ranges of the Cobb angle, (table 2, figure 1). Furthermore, this ratio increases in the more serious cases. So the scoliotic girls-to-boys ratio turns from 2:1 at values of the Cobb angle of 10°-19°, to 14:1 when the Cobb angle is 20°- 40°. Depending on the location on the vertebral column the scoliotic curves are double curves (DB) 33.3%, lumbar curves (L) 20.0%, thoracic curves (T) 18.9%, thoracolumbar curves (TL) 27.8%. In scoliotic boys the left sided scoliotic curves predominate over the rightsided ones, regardless of the type of the curve, whereas in scoliotic girls a predominance of Right Thoracic and Left Lumbar curves was observed. Table 1: The steps in detecting and treating scoliotic children at Thriasio Pedio

Screened population

Children referred for further examination at Hospital (referrals)

Children who were finally examined at outpatients at Thriasio Gen. Hospital

Children referred for radiological examination

Scoliotic children followed up

Scoliotics treated with BOSTON BRACE

Girls

1533

170

115

77

48

15

Boys Girls/ Boys ratio Total

1506

92

63

41

26

1

1.01 3039 (100%)

1.84 262 (8,6%)

1.82 178 (5,8%)

1.87 118 (3,9%)

1.84 74 (2,4%)

15 16

(0,5%)

78

T.B. Grivas ct al. /School Screening in the Heavilv Industrialized Area

Figure 1: the ratio between scoliotic boys and girls

3. Discussion Thriasio Pedio is an area of particular interest. It is the main industrial area of Attica. It is inhabited by people who belong to a great variety of ethnic groups (native Greeks, Greeks who emigrated from the former Eastern Europe and the USSR, Gypsies, emigrants from Albania). They exercise various occupations (agricultural, industrial workers), and they are of a divergent range of educational status (analphabets, alumni of elementary school, high school and university) and of social classes. On the other hand, Thriasio Pedio is undoubtedly the most industrialized area of Greece: petrol refineries, metal industries, shipbuilding companies, chemical industries are the great majority of industries concentrated in this area, where approximately 300.000 industrial workers earn their daily living. High industrialization is accompanied by a proportional amount of environmental pollution, which was not followed by any improvement of the available Health Services. The referred pupils at Thriasio Pedio represent the 8,6 % of the examined population. This relatively high percentage of the referrals can be explained by the fact that in the beginning of the School screening a lower pass-fail criterion has been applied, namely ATR^6_. The purpose of the usage of the lower ATR was the attempt to select a group of children for clinical follow up and study of the natural history of their trunk asymmetry. On the other hand, the criterion of ATR>7° has been strictly followed in children who were examined by X-rays: only 118 (3,9 %) of the total of the examined pupils underwent radiological examination. This percentage is comparable to results published in other studies [4,5], which state that the ATR>7_ criterion leads to a referral ratio for radiological examination of about 3 % of the examined population. This criterion limits the false negative and false positive cases and thus lowers the total cost of School screening and the potential social discomfort to parents and children (psychological concern and absence from work or school) [4,6]. The incidence of AIS at Thriasio Pedio (2.9%) is comparable to the overall incidence (2,6%) of School screening - detected AIS in other geographic

T.R. Grivas et al. /School Screening in the Heavily Industrialized Area

79

departments in Greece [7]. It seems that the known environmental and social economic factors do not influence the incidence of AIS. Table 2: the number of the scoliotic children depending on the size of the Cobb angle COBB ANGLE 10_-19_ MALE

TYPE OF CURVE

DB L T TL

Scoliotic children

Count % within sex& Cobb angle

FEMALE

Left

Right

Left

Right

5 5 3 3 16

2 1 3 4 10

6 5 3 8 22

10 2 6 8 26

26 28,9

48 53,3

MALE Left

20_-40_ FEMALE

Right

Left

Right

1

2 3

1

1 6

5 1 2 1 9

1 1,1

15 16,7

Scoliotic children % Count within curve 30 33,3 18 20,0 17 18,9 25 27,8 90 100

The girls at Thriasio Pedio are more susceptible to develop scoliosis compared to boys. The same applies for Thessaloniki and loannina [8,9] but not for Kriti [10], where scoliosis affects equally both sexes. Several authors report a higher prevalence of AIS in girls [11,12,13,14], while other authors did not observe any difference [5,15,16]. After regular follow up of scoliotic children in Thriasio Pedio detected by school screening, Boston Brace was applied in 16 cases, of which the vast majority were girls (15 girls vs. 1 boy). Prevention of AIS focuses on early detection and on early initiation of treatment. It thereby aims to stop the vicious circle of the natural history of scoliosis and even to reverse it [5,17]. It is well known that scoliosis develops (worsens, resolves or remains) following the changes of the growing skeleton [4,18]. The early detection and the appropriate follow up of the population at risk to develop scoliosis [19] should be part of the available Public Health Services in order to protect the population from subsequent mental, physical and social complications attributed to severe scoliosis. 4. Conclusion The incidence of School screening detected AIS in Thriasio does not differ significantly to the overall incidence of AIS in Greece. This implies that industrial environmental factors probably do not influence the prevalence of AIS. This fact does not exclude the possibility that other than industrial environmental factors might be implicated in the development of AIS in this particular area, but more data are required to prove such a suggestion.

T. B. Grivas el al. / School Screening in the Heavily Industrialized Area

References 1. 2. 3. 4. 5. 6. 7. 8. 9.

10.

11. 12.

13. 14. 15. 16. 17. 18. 19.

Murrell GAC, Coonrad RW, Moorman CT, III, Fitch RD. An Assessment Of The Reliability Of The Scoliometer, Spine 1993:18(6) 709-712 Huang, S-C. Cut-off Point of the Scoliometer in School Scoliosis Screening Spinel997; 22: 1985-1989 Aunnell WP. The natural history of scoliosis. Clin Orthop 1988; 229:20-5. Bunnell WP. An objective criterion for scoliosis screening. J Bone Joint Surg [Am] 1984;66:1381-7. Lonstein JE, Bjorklund S, Wanninger MH, et al. Voluntary school screening for scoliosis in Minnesota. J Bone Joint Surg [Am] 1982; 64:481. Bunnell, WP. Outcome of Spinal Screening, Spine, 1993,18:(12), 1572-1580. Grivas TB, Koukos K, Koukou U, Theocharis N, Samelis P: 2001: Idiopathic Scoliosis - The analysis of the results of School screening in Greece. Abstract Book, Orthopaedics, 14, (2), 32 Kapetanos G: School screening in Macedonia: In: Grivas TB (ed): School screening for Scoliosis, Athens Paschalides Medical Publications, 2000, ISBN 960-7398-74-2, pp 48-53. Soultanis K, Zacharis K, Gelalis I, Soucacos PN: School screening in loannina. Identification and comparing study of Idiopathic Scoliosis in 4 geographical compartments in Greece. In: Grivas TB (ed): School screening for Scoliosis, Athens Paschalides Medical Publications, 2000, ISBN 960-7398-74-2, pp 26-33. Koukourakis I, Kouvidis I, Giannakoudakis N, Garefalakis N, Giaourakis G: School screening in Crete. In: Grivas TB (ed): School screening for Scoliosis, Athens Paschalides Medical Publications, 2000, ISBN 960-7398-74-2, pp 71-80. Chan A, Moller J, Vimbani G, Paterson D, Southwood R, Sutherland A: The Results of scoliosis screening in Australian adolescents. Med J Aust 145:379-383, 1986, Palmisani M, Bettini N, Gargiulo G, Nardi Y, Rizqualloh F, Cosco R, Savini R: The epidemiology of idiopathic scoliosis in the city of Bologna: A three year review of positive cases. ChirOrgani Mov 75:353-360, 1990., Weinstein, MD: Adolescent Idiopathic Scoliosis: Prevalence and Natural History: Instructional Course Lectures 1989, Volume 38:115, Soucacos NP, Soucacos K.P, Zacharis CK, Beris EA and Xenakis AT: School screening for scoliosis. J. Bone Joint Surg. 79A: 1498., 1997. Smyrnis PN, Valavanis J, Alexopoulos A, Siderakis G, Giannestras NJ: School screening for scoliosis in Athens. J Bone Joint Surg [Br] 61:215-217, 1979, Brooks HL, Azen SP, Gerberg E, Brooks R, Chan L: Scoliosis: A prospective epidemiological study. J Bone Joint Surg [Am] 57:968-972,1975. Ashworth, MA (ed.). Symposium on school screening for scoliosis. Scoliosis Research Society. Spine 1988; 13:1177. Dhar, S., Dangerfield, P. H., Dorgan, J. C., and Klenerman. Spinel993, 18:(1) 1419.Correlation Between Bone Age And Risser's Sign In Adolescent Idiopathic Scoliosis Soucacos PN, Zacharis K, Gelalis J, Soultanis K, Kalos N, Beris A, Xenakis T, Johnson EO. Assessment of curve progression in idiopathic scoliosis. Eur Spine J (1998) 7: 270-277

Th.B. Grivas (Ed.) Research into Spinal Deformities 4 IOS Press. 2002

Biomechanical factors affecting progression of structural scoliotic curves of the spine S. Lupparelli, E. Pola, L. Pitta, O. Mazza, V. De Santis, L. Aulisa Clin. Orthop. Pol. A. Gemelli - Universit_ Cattolica delSacro Cuore, Roma, ITALY Abstract: The development of the spine is affected by both biological and mechanical factors. As the geometry of the motion segment changes throughout growth, so does the mechanical behaviour of the spine owing to changing vectors acting on a variable geometry system. The biomechanical analysis of the growing spine enables the assessment of the role played by biological and mechanical factors in the pathogenesis of progressive scoliosis to be assessed and its comparison with factors acting on an adult scoliotic spine. The knowledge of these principles is instrumental to setting the right parameters for treatment and to design braces that may be capable of obtaining correction of the deformity. The elastic behaviour of child and adult spine differs because of both physiologic and pathologic conditions. In child scoliosis an abnormal geometry causes a persistent stress concentration in crucial areas of the motion segment. This induces a progressive elasto-plastic strain which modifies the geometry of the motion segment, thus worsening the stress concentration and the excessive strain through a vicious cycle. In adult scoliosis, on the other hand, deformation primarily affects the viscous-elastic structures, namely the intervertebral disc and the capsuloligamentous structures. This produces instabilty of the motion segments and slow deformation of the vertebrae through remodelling. It therefore ensues that the aim of the treatment differs in both conditions. In the child spine the aim is to prevent the motion segment deformity by means of braces which adequately modifies the stress distribution acting on the spine, thus enabling the spine to grow according to a quasi-physiological model. In adult scoliosis a stable equilibrium is required in order to prevent further deformation of the motion segment.

1.

Introduction

The evolutionary process of the skeletal deformities, and of the spine in particular, is conditioned by both biological factors and by the mechanical behaviour imposed by the new geometry of the system. The treatment of scoliosis and of hyperkyphosis follow such a principle. This resulted in the realisation of orthosis which, interfering with the natural dynamics of the spine, allowed, in the most successful cases, to get a substantial stabilization of the deformity. However, a less empirical biomechanical approach would specify the therapeutic choices and would design garrisons able to offer, when possible, a meaningful recovery of the deformity. The importance, therefore, of biomechanical studies aimed at defining the role played by the mechanical factors in the pathogenesis of the deformity is clear.

81

S. Luppeirelli el cil. / Kiomechanical Factors Affecting Progression

2. Elastic behaviour of the spine In previous studies it has been observed that a spine in natural equilibrium is, in mechanical terms, an elastic carrying structure organized in many segments of movement; this structure is in a coercive state and so it is charged by bound energy [I]The entire spine, during the movements deriving from the natural dynamics, is subject to an elastic deformation. The spine structure has the capability of quickly returning to the primitive configuration when the actions that have produced the same deformation cease. The capability of returning, after every elastic deformation, to a ready and complete recovery of the natural state proves that the bound could be considered to have little importance in comparison to the elastic one. In this recovery of the natural state a physical phenomenon occurs, which, in the mechanical analysis of a system, takes the name of dynamic stability of a structure. The behaviour of an injured spine is different, since the loss of or the deterioration of some restriction bounds impose an unnatural mobility, followed by an altered elastic behaviour. In fact, while the intact column has a minimum bound energy, the injured spine, due to the incapacity to achieve a complete recovery of the natural state, has a progressively increasing bound energy. In the damaged spine a progressive increase of the elasto-plastic deformation will occur, at the elastic ones' expense, resulting in the generation of coercive states which are linked to some internal actions that progressively modify the geometric configuration of the whole structure. 3. Elastic behaviour of the scoliotic spine The scoliotic spine, because of the complex anatomical alterations that characterize it, changes in a meaningful way its own mechanical behaviour. In fact, the appearance of abnormal restraining reactions modifies the elastic properties of the system, favouring the accumulation of bound energy. Moreover, geometry's alteration induces a new model of the stress distribution, to which follows a concentration of tensions in specific areas of the vertebrae, of the disks and of the capsulo-legamentosus apparatus. The altered elastic behaviour and the concentration of the tensions induce coercive states and relative elasto-plastics deformations of the system. Such a mechanical behaviour can produce a permanent condition of unstable equilibrium. Therefore, the geometric configuration of the curve can progressively change, as time passes, due to mechanical factors. However, it is necessary to underline that the progression of a scoliotic curve is conditioned by the capacity of the biological structure to react to the induced forces and by the type of answer that the different structures offer to the same forces. According to such a principle, both the skeletal maturity level and the elastic characteristics of the restraining elements, moreover the characteristics of the intervertebral disks, take great importance. Age influences the different evolutive behaviour of the scoliotic curve, leading to the distinction between infanto-juvenile and adult scoliosis, based on clinical data. This concept is amply confirmed by the biomechanical analvsis.

S. Lupparelli et al. / Biomechanical Factors Affecting Progression

Infanto-juvenile scoliosis is characterized by the quick evolution, until the spine reaches the skeletal maturity. The plasticity of the bone tissue in growth mostly contributes to the worsening of the scoliotic curve. In the deformed spine, the action of the loads translates as concentrations of tensions in specific vertebral areas, and determines, due to the plastic reaction to the actions, typical of the growing bone, an asymmetrical development of the pedicles, of the vertebral soma and of the neural arch. The consequence is that, during growth, the scoliosis gets worse as the result of the progressive deformation of the vertebrae curve. Adult scoliosis, instead, are characterized by a slow development, so much that, for a long time, it has been considered not evolutive. Nowadays, the tendency to worsen recognizes, as principal cause, the instability of the movement segments included within the curve, if vertebral microfractures has been excluded. In the adulthood the instability shows as a progressive elasto-plastics deformation of the ligamentosus and diskal structures. It follows a deterioration of the restraining reactions with the formation of abnormal bounds. This modifies all the angular movements of the motion segments, in the three dimensions of the space. Instability is expressed by a progressive alteration of the geometric relationships between the single vertebrae, which determines subluxation phenomena in rotation and kyphosis of the movement segments included in the curve. As for the capacity of the biological structure to react to the induced loads, particular importance has the viscous-elastic ownership of the restraining elements. These, in fact, undergo many variations in relationship to both the age of the patient and the location of the deformity, and are able to condition, from a quantitative point of view, the phenomena expressed by mechanical factors. Such a behaviour can be studied by the biomechanical analysis of the G modulus of torsion rigidity of the intervertebral disks, that expresses, from a qualitative point of view, the resistance of the disks to the torsion determined by the action of a couple of forces. In previous studies it has been analysed, through a spine model, the course of the rigidities in relationship to the position of the disks in the spine and to the age of the person [2], [3] [4] (Fig. 1 and 2). In such a spine model, the G modulus presents, in the T2-T7 tract, elevated values and an homogeneous course. The high values, expression of a greater rigidity, that limits the torsion phenomena, and the homogeneous distribution, explain why the curves that include such disks are characterized by a harmonic evolution distributed through the motion segments included in the curve. In the lumbar spine, on the contrary, the values of the G modulus of torsion rigidity are inferior and are not homogeneously distributed, showing a significant reduction in skull-caudal direction. Therefore, the lumbar curves are characterized by a disharmonic evolution due to rotatory subluxation phenomena. Moreover, low G modulus of the lumbar disks, in association to the spine imbalance in the area with the most elevated loads, justifies the high degree of instability of the lumbar curves.

83

84

.S LitpfKirelli ct til. / Riomcchanutil Factors Affci

Fig.l Variation of the G modulus of elasticity of the disks in the adult model spine

Fig. 2 Variation of the G modulus of elasticity of the vertebral disks from T3 to L5 depending on age. The curves, shown as DT8....DT12 and DL1....DL5, rapresent the diagrams of the G values of the disks below respective vertebra.

S. Lupparelli et al. / Biomechanical Factors Affecting Progression

4. Conclusions In infanto-juvenile age the worsening of the scoliosis is the expression of a progressive deformation of the vertebrae, induced by an abnormal concentration of loads. The therapeutic act, therefore, must aim to reduce significantly such concentration and, where possible, to produce an inversion of the loads. In the presence of evolutive curves, therefore, the only valid therapeutic garrison is the brace, which, to be effective, must be used full time, until growth end [5] [6] [7]. In adulthood the most important factor of worsening is represented by the degree of instability, that varies in relationship to the location of the curve. The therapeutic approach to the adult scoliosis is based on the statement that is not possible to make a sure prognosis based exclusively on mechanical criteria. The reactions of the biological structure are able to influence the evolutive course of the scoliosis or, more rarely, to stop it, reaching a new equilibrium or forming new bounds, hi fact, during the structuring process of the curve, with the loss of some bound restriction, the biological structure is able to restructure itself creating new bounds, to guarantee a condition of stable equilibrium [8]. These are partly documentable and show by the hypertrophy of the articular apophyses, by the formation of osteophytes that determine a partial absorption of the loads and by the spontaneous arthrodesis of one or more segments. The therapeutic act of the adult scoliosis will be related to the degree of instability. In the minor instability the aim is to reduce the intensity of the loads and to optimise their distribution. This aim can be obtained with isometric exercises and with a correct educational posture. In the mild instabilities it can be useful the use of a brace in the period of restructuring of the curve. The treatment of the severe instabilities is, instead, surgical.

References 1.

Vinciguerra A, Aulisa L, Ceccarelli M. Stabilita e comportamento elastico del rachide. Minerva Orlop Traumatol 37: 717-723,1986

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Fineschi G, Aulisa L, Vinciguerra A. La rigidezza del rachide alia torsione. Progr Patol Vert 11:109-117,1990

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Aulisa L, Vinciguerra A, Tamburrelli F, Lupparelli S, Di Legge V. Biomechanical Analysis of the Elastic Behaviour of the Spine with Aging. In: Research into Spinal Deformities 1, J. A. SevastiK and K. M. Diab (Eds.) IOS Press: Amsterdam, 1997, pp. 229-231. Vinciguerra A, Di Benedetto A, Aulisa L. Sulla determinazione delle caratteristiche elastiche del rachide toracolombare. Minerva Ortop Traumatol 35: 133-138,1984 Aulisa L, Di Benedetto A, Vinciguerra A. Un'analisi biomeccanica del sistema tutore-rachide nelle scoliosi idiopatiche. Arch Putti 31: 185-194,1981 Aulisa L, Vinciguerra A, Valassina A, La Floresta P. II trattamento ortopedico mediante corsetto P.A.S.B. Progr Patol Vert 12: 135-142,1991

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Fineschi G, Aulisa L, Vinciguerra A, Valassina A. Aspetti biomeccanici dei corsetti per il trattamento incruento della scoliosi. Minerva Ortop Traumatol 44: 543-548,1993

8.

Di Benedetto A, Vinciguerra A, Pennestr_ E, Aulisa L. Biomechanics of scoliosis using a new type of brace. In: Proceedings of the 8th Canadian Congress of Applied Mechanics, Moncton, N-B, Canada, June 7-12, pp 785-786,1981

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Tli.B. GrivasiEdi Rcseiirch into Spinal Deformities 4 I OS Press. 2<><>2

Positional cloning strategies for idiopathic scoliosis Stavros Bashiardes', Rose Veile', Carol A. Wise^, Laszlo Szappanos^, Michael Lovett* 1 Department of Genetics, Washington University School of-Iedicine, St. Louis, AIO, USA

2 Sarah Al. and Charles E. Scay' Center for Alusculoskeletal Research, Texas Scottish Rite, Hospital for Children, Dallas, TX, USA Abstract. >4rm: Idiopathic scoliosis (IS) affects approximately 1-2% of the population and has a heritable component. It is clear that in general IS displays the features of a complex genetic disorder; however families displaying a Mendelian inheritance pattern have been described. Our aim is to identify families segregating rare, highly penetrant loci. In the case described here the disorder appears to cosegregate with a chromosomal rearrangement. Methods and Materials: We have studied a family in which a pericentric inversion of chromosome 8 appears to cosegregate with idiopathic scoliosis in three generations. We have used fluorescent in situ hybridization (FISH) to identify cloned DNAs that span the breakpoints on the two arms of the chromosome. These clones allow the recovery of sequence information from the breakpoint region and identification of candidate genes. Results: We have identified a YAC of 1190kb that spans the p arm breakpoint and from this a cosmid of 35kb that also identifies the break. We have derived DNA sequence information on this region. We have identified a BAG of 150kb that crosses the q arm breakpoint. The complete genomic DNA sequence of this BAC is being analyzed to identify candidate genes and to further localize the precise breakpoint. Conclusion: We have sublocalized within two small genomic regions the position of a possible locus for idiopathic scoliosis.

The familial nature of idiopathic scoliosis (IS) has been widely described [1,2] and many epidemeological studies have suggested that approximately one third of IS cases may be familial [3] Even though a strong genetic component for IS is generally accepted, the mode of inheritance is unclear and the available studies sometimes support conflicting theories. The overall risk of scoliosis exponentially declines as one progreses from first to second to third degree relatives. This is consistent with a multi-factorial mode of inheritance [4]. At present, the genetic components that underly multi-factorial disorders can be identified by four distinct routes. Genetic linkage/association studies on large family collections or collections of sporadic cases, coupled with positional cloning methods are routes that hold great promise. However, this type of approach is severely complicated by the fact that IS appears to be both heterogeneous in its' genetic causes and also frequent in occurrence. Gene expression profiling methods, such as gene chips or Serial Analysis of Gene Expression (SAGE) are also very powerful methods for the identification of potential key players (and genetic loci) in disease states [5]. Unfortunately, this type of analysis is difficult to apply to IS because it is unclear what tissue(s) to profile and which exact comparisons should be made. Another successful route into the genetic underpinnings of

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complex disease is to ideunfy families that exhibit early onset disease and that appear to segregate highly penetrant alleles. We recently applied this approach in the successful cloning of a gene that causes a severe immunoinflammatory disease [6]. The final approach is to identify a chromosomal alteration that results in the disease state cloning [7, 8]. Balanced chromosomal rearrangements that cosegregate with disease have proved extremely useful in the identification of the molecular basis of many Mendelian traits. Type 1 neurofibromatosis [9, 10], poly cystic kidney disease [11], Duchenne muscular dystrophy [12] and Lowes syndrome [13] are just a few examples of diseases that have benefited from this approach. Chasing chromosomal breakpoints as markers for the location of susceptibility genes is open to the criticism that the correlation may be coincidental. In this context it is relevant to point out that a large epidemiologi cal study of early developmental disorders [14] concluded that about two thirds of observed chromosomal abnormalities were probably causally related to these early onset disorders. When later onset disorders are considered (such as IS) this number may be much higher.

Figure 1: Family with scoliosis in three generations used in our study. Father and son (X-ravs indicated) have a common chromosomal rearrangement identified as a pen centric inversion of Chromosome 8.

Therefore, as a parallel approach to our ongoing positional cloning strategies, we sought to identify a balanced chromosomal rearrangement in at least one familial IS pedigree. One small family we have studied, with scoliosis in three generations, appears to cosegregate with a pericentric inversion of chromosome 8. The G-banded metaphase of one affected member is shown in Figure 1. Our strategy to identify the precise breakpoint involved using genomic information to walk to and clone the chromosomal break regions and identify flanking genes.

Figure 2: G-banded Metaphase of father. Wildtype Chromosome 8 and Chromosome 8 wiLh pericentrie inversion are shown bv arrows.

8S

5. Bashiardes el ai / Positional Cloning Strategies for Idiopathic Scolio.iix

Fluorescence In Situ Hybridization (HSH) was used to identify YAC and BAG clones that spanned the breaks on the p-arm and q-arm of chromosome 8. These clones were used to walk to those regions, identifying ones that lie above, below and across the breaks. The position these BACs and YACs map to on the chromosome with respect to the breakpoints were classified according to the location that fluorescence was observed on the chromosome during the FISH experiments (Figure 3). The actual results observed during our HSH experiments are illustrated in Figure 4. In this case, we are illustrating results with respect to the q-arm of the chromosome, the same principle was applied to clone the p-arm break point. The BACs and YACs that were characterized as crossing the breakpoints

Figure 3: Schematic representation of results expected during FISH experiments. All representations of expected FISH results are shown for q-arm. (A) indicates the pericentric inversion occuring (B) Position of BAC hybridization and consequently fluorescence of a BAC that maps below break point. (C) Position of Fluorescence for a BAC that maps above break point. (D) Position of fluorescence for a BAC that crosses the break point

were subdoned into cosmids and those that crossed the breaks were identified by FISH. Sequence information from these cosmid clones and comparison with the completed human genome sequence was used to determine the presence of disrupted genes in the region. This analysis revealed that the p-arm does not appear to break any known gene whereas in the q-arm we have identified a gene that is disrupted by the break

Figure 4: Results obtained during FISH experiments. (A). BAC that maps below break on q-arm. (B) BAC that maps above break on q-arm. (C) BAC that crosses break point on q-arm.

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occurring during the pericentric inversion. Currently, we are analyzing sporadic IS patients for mutations in the identified genes using predicted exon sequences.

References 1. 2. 3. 4. 5. 6.

7.

8. 9.

10. 12.

13.

14.

Beals, K. K. Nosologic and genetic aspects of scoliosis. Clinical Orthopaedics 93 (1973) 23-32 Hairington, P.R. The etiology of idiopathic scoliosis. Clinical Orthopaedics 126 (1977)17-25 Weinstein, S. L. Advances in the diagnosis and management of adolescent idiopathic scoliosis Journal of Pediatric Orthopaedics 11(1991) 561-3 Riseborough, B. J., Wynne Davies, K. A. Genetic survey of idiopathic ScoliosiS in Boston, Massachusetts. Journal of Bone and Joint Surgery 55-A (1973) 974-982 Blackshaw, S., Fraioli, K. E., Furukawa, T., Cepko, C. L. Comprehensive analysis of photoreceptor gene expression and the identification of candidate retinal disease genes. Cell 107 (2001) 579-589 Wise, C. A., Gillum, J. D., Seidman, C. E., Lindor, N.M., Veile, K., Bashiardes, S., Lovett. M. Mutations in CD2BP- disrupt binding to RYP PEST and are responsible for PAPA syndrome an autoinflammatory disorder. Human Molecular Genetics 11 (2002) 961-969 Bugge, M., Bruun-Petersen, G., Brondum-Nielsen, K., Friedrich, U., Hansen, J., Jensen, G., Jensen, P. K. A., Kristoffersson, U., Lundsteen, C., Neibuhr, E., Rasmussen, K. R., Rasmussen, K., Tommerup, N. Journal of Medical Genetics 37 (2000) 858-865 Collins, F. S. Positional cloning moves from perditional to traditional. Nature Genetics 9 (1995) 347-350 Fountain, J. W., Wallace, M. K., Bruce, M. A., Seizinger, B. R., Menon, A. G., Gusella, J. F., Michels, V. V., Schmidt, M. A., Dewald, G. W., Collins, F. S. Physical mapping of a translocation breakpoint in neurofibromatosis. Science 244(1989)1085-1087 The European Polycystic Kidney Disease Consortium. The polycystic kidney disease I gene encodes a ~4kb transcript and lies within a duplicated region on chromosome 16. Cell 77(1994) 881-894 Ray, P. N., Belf~l, B., DuIT, C., Logan, C., Kean, V., Thompson, M. W., Sylvester, J. E., Gorsky, J. L., Schmickel, K. D., Worton, R. G. Cloning of the breakpoint of an X:21 translocation associated with Duchenne muscular dystrophy. Nature 318 (1985) 672-675 Attree, 0., Olivos, I. M., Okabe, I., Bailey, L. C., Nelson, D. L., Lewis, K. A., Mclnnes, K. K., Nussbaum, K. L. The Lowels oculocerebrorenal syndrome gene encodes a protein highly homologous to inositol polyphosphate~5~phosphatase. Namre. 358 (1992) 239-42 Warburton D. DC novo balanced chromosome rearrangements and extra marker chromosomes identified at prenatal diagnosis: clinical significance and distribution of breakpoints. American Journal of Human Genetics 49 (1991) 995-1013

Research into Spinal Deformities 4 IOS Press. 2002

Prediction of Curve Progression in Idiopathic Scoliosis from Gene Polymorphic Analysis Masatoshi Inoue, Shohei Minami, Yoshinori Nakata, Masashi Takaso, Yoshinori Otsuka, Hiroshi Kitahara, Keijiro Isobe, Toshiaki Kotani, Tetsuro Manila, Hideshige Moriya. Department of Orthopedic Surgery, School of Medicine, Chiba University, 1-8-J Inohana, Chuo-ku, Chiba, Japan.

Abstract. Three hundred and four girls with adolescent idiopathic scoliosis were investigated to determine if DNA polymorphisms in the vitamin D receptor (VDR), estrogen receptor (BR), and CYP17 gene were related to curve progression of idiopathic scoliosis. The results suggested that XbaJ site polymorphism in the ER gene was associated with curve progression. The Cobb's curve angle with genotype XX and Xx was statistically greater than that with genotype xx. The curve progression risk (~5 degrees) was higher for genotype XX and Xx than for genotype xx. Furthermore, patients with genotype XX and Xx had a higher risk of receiving operative treatment than those with genotype xx. In conclusion, DNA analysis may predict curve progression, although other polymorphisms were not associated with curve severity.

1.

Introduction

Many research studies have been performed to identify factors that predict curve progression in idiopathic scoliosis. Twin studies revealed that curve progression was related to a hereditary factor [1,2], while other studies indicated that it was influenced by skeletal and sexual maturation [3, 4, 5]. Currently, growth and sexual maturation in girls are considered to be influenced by hereditary factors. Techniques of DNA analysis have revealed that nucleotide sequence variation in the human genome is common. These single base pair differences in DNA nucleotide sequence are inherited in Mendelian codominant manner. If a DNA sequence difference occurs within a restriction enzyme recognition sequence, the restriction enzyme fragments produced will be different lengths in different people, producing restriction fragment iengdi polymorphisms (RFLPs). Several investigators recently ascertained that RFLPs of several genes were responsible for menarcheal age as well as increase in height. Genes associated with growth in height include the vitamin D receptor (VDR), estrogen receptor (ER), and dopamine receptor (DRD2) [6, 7, 8, 9], while genes associated with menarcheal age include VDR and CYP17 [10, 11].

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Since in scoiiosis, curve progression is influenced by growth and puberty, we hypothesized that some variant of these genotypes might be related to curve progression in idiopathic scoiiosis. The purpose of this study was to investigate the relationship between DNA polymorphisms found in the VDR, ER, and CYP17 gene and the severity of idiopathic scoiiosis

2. Patients and Methods Patients with idiopathic scoiiosis were evaluated by clinical examinations and roentgenograms. The curves were measured by Cobb's method, and girls with a curve greater than 10 degrees with rotation were included. All patients were followed until growth maturation, and the maximum Cobb's angle during follow-up was selected for analysis. In addition, curve progression was defined as progression greater than 5 degrees from the initial evaluation. Exactly, 304 girls with adolescent idiopathic scoiiosis, who gave informed consent to DNA analysi- could be followed until the time of growth maturation. The mean (L SD) initial Cobb's angle was 24.6 ±10.0 degrees, and the mean (±SD) maximum Cobb's angle during follow-up was 31.3± 12.6 degrees. The mean menarcheal age was 12.3±1.2 years, and the mean age at growth maturation was 15.0±1.6 years. The mean (±SD) height was 158.3±5.6 cm, while the mean arm span was 161.6±6.4cm. The indication for brace treatment was a curve magnitude greater than 25 degrees with a Risser grade of 3 or less, and that for surgery was a curve magnitude greater than 45 degrees. In sum, 42,109, and 153 patients received operations, brace treatment, and did not undergo curve progression or refused brace treatment, respectively. As for the curve pattern, if minor curves were 10 degrees or more, a curve pattern was defined as a double curve. In sum, 189, 62, 25, 13, and 15 patients had double curves, a right thoracic curve, a thoracolumbar curve, a lumbar curve, and triple curves, respectively. Patient lymphocyte DNA samples were extracted from peripheral blood. The restriction fragment length polymorphisms (RFLPs), which included the VDR Apal, Fokl, and the TaqI site polymorphism, the ER PvuII and the XbaJ site polymorphisms, and the CYP17 MSPAI site polymorphism, were selected for analysis. All RFLPs were first amplified using the polymerase chain reaction (PCR) as described previously [6,7,11, 12], and then subsequently digested with each restriction enzyme, with the genotypes determined by gel electrophoresis. The RFLPs were coded as Pp (PvII) and Xx (Xbal), where the uppercase letter indicates the absence of the site, and the lowercase letter indicates its presence. Association between each genotype and the maximum Cobb's angle, and association between each genotype and idiopathic scoiiosis treatment were compared using the x^ test or the one-way analysis of variance (ANOVA) as appropriate. P value differences of 0.05 were considered statistically significant.

M. Inoue et al. /Prediction of Curve Progression in Idiopalhic Scoliosis

3. Results Table 1 shows the VDR, ER, and CYP17 genotype distribution. The frequency ofApal, Fokl, and TaqI site polymorphisms for the VDR genotypes and MspAl for the CYP17 genotype in idiopathic scoliosis patients was not significantly different from controls previously described [6, 7, 11]. As for the ER genotype distribution, the PvuII site polymorphism frequency was not significantly different from controls previously described. However, the genotype XX frequency for the Xbal site (Group A) was 14%, which was greater than the 3% frequency reported by other groups [12, 13,14]. As for the ER gene, the Xbal site polymorphism was associated with curve severity. The mean (± SD) Cobb's angle with genotype XX and Xx was greater than that with genotype xx, with statistically significant differences (Table 2). The ER PvuII site polymorphism was unrelated to curve severity. Furthermore, other polymorphisms in the VDR and CYP17 genes were not associated with curve severity (Table 2). Table 1. Genotye distribution in each group Gene RFLP Group A VDR Apal 0.10 VDR Fokl 0.46 VDR TaqI 0.80 ER PvuII 0.21 ER Xbal 0.14 CYP17 MspAl 0.27

Group B 0.47 0.46 0.18 0.47 0.25 0.55

Group C 0.43 0.08 0.02 0.32 0.61 0.18

Group A: restriction site absence in both alleles, such as XX or PP Group B: heterozygous, such as Xx or Pp Group C: restriction site in both alleles, such as xx or pp

Table 2. RFLPs and curve severity association Cobb's angle (degree) Group B Gene RFLP Group A 31.9±15.8 31.3±12.1 VDR Apal 30.5±11.9 31.6±12.8 VDR Fokl 31.0±12.7 VDR Taql 31.5±11.9 ER PvuII 33.6±14.6 31.1±12.3 34.2±13.7 34.9±15.8 ER Xbal 30.2±12.4 31.2±12.7 CTP\7MspAI Data are mean ±SD. N. S.: not significant (P>0.05). Group A: restriction site absence in both alleles, such as XX or PP Group B: heterozygous, such as Xx or Pp Group C: restriction site in both alleles. such as xx or pp

P value Group C 30.5±12.1 32.2±15.1 30.6±15.7 30.1±11.7 29.3±11.0 29.8±12.5

(ANOVA) N. S. N.S. N.S. N.S. 0.002 N.S.

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Table 3. RFLPs and curve severity association (The brace treatment patients were excluded) Cobb's angle (degree) P value Group B Group C Gene RFLP Group A 30.6±19.7 27.6±16.3 31.4±26.3 VDR Apal 27.8±17.9 34.0±24.5 30.2±18.8 VDR Foki 29.0±22.5 30.9±22.5 29.1±18.3 VDR TaqI 30.1±17.6 34.2±21.7 25.6±15.3* ER PvuII 36.3±18.7 35.3±21.8 24.5±14.8 ER Xbal 30.0±19.5 27.2±18.0 27.6±16.9 CYPllMspAl

(ANOVA) N. S. N. S. N. S. N. S. <0.001 N. S.

Data are mean ±SD. N. S.: not significant (P>0.05). *P<0.05 vs Group A by x2 test. Group A: restriction site in both alleles Group B: heterozygous Group C: restriction site in both alleles

When patients treated with braces preventing curve progression were excluded, the Xbal site polymorphism was also associated with curve severity, and the Xbal site polymorphism genotype was more significant (P < 0.001) (Table 3). Furthermore, the PvuII site polymorphism genotype was associated with curve severity, and the mean (± SD) Cobb's angle with genotype PP became greater than that with genotype pp (P <0.05) (Table 3). The patient risk with curve progression and receiving operative treatment were compared among each genotype. The RFLPs in the VDR and CYP17 gene were not associated with curve progression, while the ER XbaJ site polymorphism was related to curve progression. The frequency of patients who had a progressive curve was greater with genotype Xx than with genotype XX and xx (P = 0.03) (Table 4). Furthermore, the risk of Cobb's angle >30 degrees was 55%, 57%, and 42% for patients with genotype XX, Xx, and xx, respectively (P = 0.04). Additionally, the risk of Cobb's angle >40 degrees was 29%, 26%, and 12% for patients with genotype XX, Xx, and xx, respectively (P = 0.004) (Table 5). Table 4. Association between ER Xbal site RFLP and curve progression Genotype Curve progression XX Xx XX 34 (44%) <5 degrees 26 (62%) 114(62%)

P value

0.03 >5 degrees

16(38%)

43 (56%)

71(38%)

Analysis was by x^ test. "Curve progression" was defined as progression greater than 5 degrees.

M4

M. Inoiie et til. /Prediction of Curve Progression in Idiopathic Scoliosi\

Table 5. Association between Xbal site RFLP and the risk of Cobb's angle >30 and > 40 degrees Genotype Cobb's angle XX Xx XX P value 19(45%) 33 (43%) 108 (58%) <30 degrees 0.04 >30 degrees 23 (55%) 44 (57%) 77 (42%)

Cobb's angle <40 degrees

XX 30(71 %)

Genotype Xx 57 (74%)

163(88%)

20 (26%)

22(12%)

XX

P value 0.004

>40 degrees Analysis was by x^ test.

12(29%)

Table 6. Association between the ER Xbal site RFLP and scoliosis treatment Genotype XX Xx XX Treatment 33 (79%) 58 (75%) 171 (92%) Non-op (<45 degrees) 9(21%) 14(8%) 19(25%) Op (>45 degrees) Op: operation Analysis was by x^ test.

P value <0.001

With regard to idiopathic scoliosis treatment, the patients with genotype XX and Xx had a higher risk of receiving operative treatment than those with genotype xx (Table 6). All other polymorphisms were not associated with idiopathic scoliosis treatment.

4. Discussion Several studies previously demonstrated that curve progression in idiopathic scoliosis was related to skeletal and sexual maturation. The results of this study suggested that the estrogen receptor (ER) gene polymorphism was also associated with curve progres~on. The ER gene is present in both human osteoblast and osteoclast cells [15, 16], and ER mutations were recently shown to cause bone loss and delayed skeletal growth in affected humans [17]. Additionally, another study revealed a correlation between the Xbal site polymorphism and a later age at skeletal maturation [18]. Together, these results suggested that the Xbal site polymorphism was related to skeletal maturation. In this study, the ER genotype distribution for the XhaJ site in idiopathic scoliosis patients was different from the distribution previously reported [8,12,13,14]. The genotype XX

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frequency was 14% in this study, while 2.9-3.5% in other studies. These results indicated that there might be a relationship between the Xbal site polymorphisms and idiopathic scoliosis onset, and that genotype XX may play a part in deformity onset. However, if this study includes girls with a spinal curve less than 10 degrees, the genotype XX frequency might decrease. Therefore, the ER genotype distribution might be similar to that in other studies. The results of the statistical analysis in this study indicated that the genotypes classified according to the ER intron one polymorphism were related to curve severity. However, it is still unclear how curve severity is affected by ER gene polymorphisms in the introns. Several investigators revealed that the PvuIJ and XbaJ site polymorphisms in the first ER intron were associated with low bone mineral density [12, 13], and the age of rheumatoid arthritis onset [14]. Although the relationship between ER polymorphism and functions remains unclear, it was suggested that ER polymorphism was of importance for bone metabolism. Furthermore, several studies have indicated that for some genes, the first intron contains regulatory sequences, such as enhancers. Whether the first intron region in the ER gene might also act as an enhancer is unclear. Further molecular studies are needed to confirm this hypothesis. In conclusion, the scoliosis curve severity was shown to be associated with the genotype of the ER gene polymorphism. This genetic analysis might be applicable to the prediction of scoliosis progression, and could help physicians decide whether early treatment is needed.

5. Acknowledgements The authors thank Dr. Makoto Tokunaga, Dr. Shinsuke Nishikawa, Miss Masako Ando, and Miss Yoko Fujimoto for their assistance in the collection of data throughout this study. This work was supported by grants from Japanese Ministry of Education, Science and Culture (NO. 13470300). References 1. 2. 3. 4 5 6 7 8

M. Inoue, S. Minami, and H. Kitahara et al., Idiopathic scoliosis in twins using DNA fingerprints, J Bone Joint SurgfBrJ 76 (1998)186-191. K. L. Kesling and K. A. Reinker, Scoliosis in twins: a meta-analysis of the literature and report of six cases, Spine 22 (1998) 2009-2014. D. S. Drummond and B. J. Rogala, Growth and maturation of adolescents with idiopathic scoliosis, Spine 5 (1980)507-511. J. B. Lonstein and M. Canson, The prediction of curve progression in untreated idiopathic scoliosis during growth, JBone Joint Surg [Am] 66 (1984) 1061-1071. T. G. Lowe, M. Edgar, and J. Y. Margulies et al., Etiology of idiopathic scoliosis: Current trends in research, J Bone Joint Surg [Am] 82 (2000)1157-1168. K. Minamitani, Y. Takahashi, and M. Minagawa et al., Differences in height associated with a translation start site polymorphism in the vitamin D receptor gene, Fedatr Res 44 (1998) 628-632. C. Tao, T. Yu, and S. Gamett et al, Vitamin D receptor alleles predict growth and bone density in girls, Arch Dis Child 79 (1998) 488-494. F. Suarez, C. Rossignol, M. Garabedian, Interactive effect of estradiol and vitamin D receptor gene polymorphism as a possible determinant of growth in male and female infants, J Clin Endocrinol Metah 10 (1998) 3563-3568.

%

9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

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D. E.Comings, S. D. Flanagan, and G. Dietz et al., The dopamine D2 receptor (DRD2) as a m4jor gene in obesity and height, Biochem MedMetah Biol 50 (1993)176-185. I. Kitagawa, Y. Kitagawa, and Y. Kawase et al., Advanced onset of menarche and higher hone mineral density depending on vitamin D receptor gene polymorphism, Fur JEndocrinol 139 (1998) 522-527. H. S. Feigelson, G. A. Coetzee, and L. N. Kolonel et aL, A polymorphism in the CYP17 gene increase the risk of breast cancer, Cancer Res 57 (1997)1063-1065. H. Mizunuma, T. Hosoi, and H. Okano et al., Estrogen receptor gene polymorphism and bone mineral density at the lumbar spine of pre-and postmenopausal woman, Bone 21 (1997) 379-383 S. Kobayashi, S. Inoue, and T. Hosol et al., Association of bone mineral density with polymorphism of the estrogen receptor gene,JBone Miner Res 11(1996)306-311. T. Ushiyama, K. Mon, and K. Inoue et al., Association of oestrogen receptor gene polymorphisms with age at onset of rheumatoid arthritis, Ann Rh earn Dis 58 (1999) 7-10. B. S. Komm, C. M. Terpening, and D. J. Benz, et al., Estrogen binding, receptor mRNA, and biologic response in osteohlast-like osteosarcoma cells, Science 241 (1988) 81-84. J. M. Pensler, J. A. Radosevich, and R. Higbee etai, Osteoclasts isolated from membranous bone in children exhibited nuclear estrogen and progesterone receptors, J Bone Miner Res 5 (1990) 797- 802. B. P. Smith, J. Boyd, and G. R. Frank et al., Estrogen resistance caused by a mutation in the estrogenreceptor gene in a man, #£/igi/M?
Th.B. Grivas (Ed.) Research into Spinal Deformities 4 IOS Press, 2002

Mechanical Modulation of Vertebral and Tibial Growth: Diurnal versus Full-time Loading Ian A. Stokes, Jodie Gwadera, Abigail Dimock, David D. Aronsson Department of Orthopaedics and Rehabilitation University of Vermont, Burlington, VT 05405-0084, USA Abstract. The aim of this study was to determine whether the amount of growth response to mechanical compression and the underlying mechanism differed with night-time or day-time loading, relative to full time loading. Mechanical compression (nominally 0.1 MPa stress) was applied across tibial and tail vertebral growth plates of growing Sprague-Dawley rats. Four groups of animals were tested: 24/24 hour (full-time loading); 12/24 hour (day-loading); 12/24 hour (night-loading); and 0/24 hour (sham instrumented), 4 or 5 animals per group. After 8 days animals were euthanized and the growth plates were processed for quantitative histology of loaded and within-animal control growth plates to measure 24-hour growth, total and BrdU-positive proliferative zone chondrocyte counts, and hypertrophic chondrocyte enlargement in the growth direction. Results: Growth as a percentage of within-animal control averaged 82% (full-time); 93% (day-loading); 90% (night-loading); 100% (sham) for vertebrae. For proximal tibiae it averaged 70% (full-time); 84% (day-loading); 86% (night-loading); 89% (sham). Reduced amount of hypertrophic chondrocytic enlargement explained about half of this effect in full-time compressed growth plates, but was not significantly altered in half-time loaded growth plates. The remaining variation in growth was apparently explained by reduced total numbers of proliferative zone chondrocytes. The BrdU labeling index demonstrated an opposite trend, which was not statistically significant. In half-time loaded growth plates the proliferative zone cell count change predominated.

1. Introduction It is thought that progression of scoliosis occurs at least in part as a result of asymmetrical forces on the vertebrae creating differential growth and hence wedging deformity. The response of bone growth to loading, and especially to diurnal variations in loading is not known quantitatively. Longitudinal growth of long bones and vertebrae occurs in growth plates, where new cells produced in the proliferative zone enlarge and synthesize extracellular matrix in the hypertrophic zone, and the tissue thus formed becomes ossified. Growth can be considered as the product of the levels of cellular activity (proliferation and hypertrophy) in these two zones. The aim of this study was to determine whether the amount of growth response to mechanical compression differed with night-time or day-time loading, relative to full time loading. We hypothesized that the growth modulation effect of half-time loading would be half that of full time loading, irrespective of whether the half-time loading was imposed during the day or night. Also, we investigated the relative contributions of changes in chondrocytic proliferation and of

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I.A Stokes et ill. /Mechanical Modulation of\'cnehral unit Tihial Growth

changes in chondrocytic hypertrophy to the mechanically induced growth modulation. The study was performed in the tail vertebral growth plates, and in the more rapidly growing proximal tibial growth plates of young rats.

2. Methods Mechanical compression was applied across the growth plates of the 7th caudal vertebra and of the right proximal tibia of 35-day-old Sprague-Dawley rats. The external loading apparatus used compression springs in an Ilizarov-style construct, adjusted to apply nominally 0.1 MPa stress. Two pins were used to transect respectively the 6th and 8th caudal vertebrae, the right tibial proximal epiphysis and the right tibial diaphysis. The apparatus was installed under general anesthesia (Ketamine 80 mg/kg and Xylazine 10 mg/kg) with post-operative analgesia (Buprenorphine 0.05 mg/kg). The tail vertebrae pins were 0.5 mm diameter, and those in the tibia were 0.3 mm diameter.

Figure 1: Radiograph showing compression apparatus installed in the tail and right tibia of a rat.

Four groups of animals were tested: 24/24 hour (full-time loading); 12/24 hour (dayloading); 12/24 hour (night-loading); and 0/24 hour (sham instrumented). There were four or five animals per group. In half-time loaded animals, spring forces were removed or applied at 'lights-on' and 'lights-off times in an artificial light cycle to which animals had previously become acclimated. Calcein (15 mg/kg) was administered systemically 24 hours prior to euthanasia, and BrdU (25 mg/kg) 30 minutes before death. All live animal procedures were reviewed and approved by the Institutional Animal Care and Use Committee.

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After 8 days, animals were euthanized and the loaded and within-animal control growth plates were removed, fixed [1], and embedded in Epon-Araldite. One micron sections were cut and mounted, and imaged at 1300 x 1030 pixel resolution using a Zeiss microscope. Twenty-four hour growth was measured from the fluorescent Calcein label. In the proliferative zone the labeling index was measured as the proportion of chondrocytes with BrdU-positive nuclei (Histostain Sp kit, Zymed Labs, San Francisco, CA) relative to the total number of cells with full nuclear profiles. The total number of full nuclear profile proliferative chondrocytes was noted. Hypertrophic chondrocyte enlargement in the growth direction was measured from stained sections (Periodic acid; Basic Fuschin; Methylene blue; Azure II) by estimating the maximum cell height from a regression relationship of the measured cell height (identified in a semi- automated process using Zeiss KS-300 software) as a function of its vertical position in the hypertrophic zone. 3. Results Growth as a percentage of within-animal control averaged 82% (full-time); 93% (day-loading); 90% (night-loading); 100% (sham) for vertebrae. For proximal tibiae it averaged 70% (full-time); 84% (day-loading); 86% (night-loading); 89% (sham) (Table 1). Reduced amount of hypertrophic chondrocytic enlargement explained about half of this effect in full-time compressed growth plates. The remaining variation in growth was apparently explained by reduced total numbers of proliferative zone chondrocytes (although the BrdU labeling index was not significantly changed). In half-time loaded growth plates the proliferative zone cell count change predominated. Table 1: Mean (SD in parentheses) of growth and measures of chondrocytes in the proliferative and hypertrophic zones, expressed as a percentage of within animal control values.

Vertebrae

G

FHt

LI

Tibiae

Np

G

FHt

LI

Fulltime

82 (9.7) 91 (6.3)

111 (22.3)

90(9.1) 70 (8.4)

92(5.1)

Day

93 (11.9)

102 (14)

125 (34)

89 (11.8)

102(4.7) 113 (17.5)

Night

90 (5.4) 98 (9.4)

105 (32)

99 (9.8) 86 (4.4)

99 (4.7)

104(41)

Sham

100 (6.2)

82 (12.9) 99 (4.0) 89 (8.2)

96 (3.9)

100 (7.3) 97 (5.8)

96 (5.7)

84 (5.6)

114 (21.8)

Np 85 (10.9) 98 (8.3) 96 (7.4)

Full-time = 24/24 hour loading; Day = loaded 06:00 - 18:00; Night = loaded 18:00 - 6:00; Sham = no spring forces. G=growth; FHt =Hypertrophic chondrocytes final height estimate; LI = BrdU positive labeling index (proliferative zone); Np = Number of full nuclear profile chondrocytes in the proliferative zone.

100

I.A. Stokes et al. /Mechanical Modulation of Vertebral and Tihial Growth

4. Discussion and Conclusions Mechanical compression of 0.1 MPa suppressed growth of vertebrae and tibiae. The half-time loading effect on growth approximated half that of full-time loading, with no difference between night-time and day-time loading. Daily longitudinal growth is approximately equal to the product of the number of new cells produced per day and the final chondrocytic height. Therefore, the percentage change in growth was expected to be equal to the sum of the percentage changes in labeling index, number of proliferating cells, and their final height. The numbers of proliferating cells and final cell height appeared to have this additive relationship with growth, but the labeling index demonstrated an opposite trend (although the differences in labeling index were not statistically significantly different). The mechanically reduced growth was produced by a combination of reduced numbers of proliferating chondrocytes and lesser chondrocytic height increase in the hypertrophic zone in full time loaded growth plates, but in those that were half-time loaded no changes were evident in the hypertrophic zone. These findings may have relevance to the mechanism of progression of skeletal deformity during growth, and its management by braces and other mechanical measures. 5. Acknowledgments: Supported by NIH R01 AR 46543. Reference 1.

Hunziker EB, Herrmann W, Schenk RK. Improved cartilage fixation by ruthenium hexaamine trichloride (RHT). A prerequisite for morphometry in growth cartilage. J Ultrastruct Res. 1982;

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Growth patterns in patients with unoperated congenital vertebral anomaly C.J.Goldberg. D.P.Moore. E.E.Fogarty. F.E.Dowling. Children's Research Centre & Orthopaedic Department, Our Lady's Hospital for Sick Children, Crumlin. Dublin 12. Ireland [email protected] /fax +353-1-455-0201 Abstract. Retrospective analysis of height and weight data recorded during routine clinic visits of children with congenital vertebral anomaly were related to decimal age and compared with national centiles. Individuals were dropped from the study at surgery. Growth followed a normal trajectory until puberty, although girls tended to be smaller than average. At puberty, they lagged behind their peers and at maturity were shorter than average. This does not appear to be a hormonal problem, and suggests a fundamental failure of growth.

1. Introduction The concept of spinal deformity as a disturbance of ontogenesis under physiological stress is supported by the frequent co-existence of other malformations [1]. Reduced stature has been described in other congenital abnormalities [3] and has been observed in developmental biology after an insult during early embryogenesis [7]. In congenital vertebral anomaly, any height deficit may be due to the spinal anomalies themselves, to surgery carried out to address these, to Cobb angle size, to a growth anomaly or to a combination of these factors. While it may not be easy to separate these influences, it is of interest for both prognosis and aetiology. 2. Materials and Methods Height (using a wall-mounted Harpenden stadiometer) and weight is routinely recorded for all patients attending the spinal deformity clinics. This data was retrieved and all measurements made after spinal surgery were ignored. Age at measurement was rounded to the nearest half year and heights were averaged for boys and girls separately at six-monthly intervals. These were compared with the national centiles [6]. Sub-ischial height of a subgroup who had been specifically measured for another study [4] were compared with the mean for age [2], to determine whether these were within the normal range, thus indicating any reduction in height attributable entirely to the spinal abnormality.

3. Results Figures 1 and 2 show graphically the mean growth trajectory of males and females from age 3 to maturity (greater than 18.5 years). 200 children were identified with at least one height measurement recorded without spinal surgery: 80 boys had a total of 572 recordings

C.J. Coldhert; et al. /Growth Patterns in Patients

and 120 girls had a total of 735. During childhood, the boys followed a normal trajectory. At age 11 years, their mean height was 140.16 ± 7.53 centimetres (cms), which is on the 50th percentile for height (141.3 ± 6.5). At maturity, their mean height was 166.36 ±7.12 cms. This is the 10th centile for Irish males (167.3 + 6.4 cms, while the 50* is 175.5 cms). The girls were more obviously affected from the start, with their mean height trajectory following the 25th centile until age 11 years. Menarche, at a mean of 13.8 years, SD 1.45. was not statistically different from the national mean of 13.52 [5]. At age 11 years, these girls had a mean height of 136.42 + 7.53 cms compared to the 50th percentile of 140.9 + 6.8 cms. At maturity, they averaged 156.98 + 5.19 cms, just above the 10* centile of 155.7 cms and well below the 50th at 163 + 5.7 cms. Thus, patients with congenital vertebral anomalies grow normally throughout childhood but, during the adolescent growth spurt, they lose impetus and, at maturity, have not reached the height that would have been predicted earlier. There were 28 patients, 13 male and 15 female, who had sub-ischial height recorded. For boys, the mean age at measurement was 15.2 + 6.8 years, range 5.4 - 27.2. The mean difference between their sub-ischial height and that of age-matched controls was -0.82 + 4.7 cms which, on paired t-testing, was not statistically significant. Girls, measured at a mean age of 18.53 + 5.6 years, range 5.5 - 27.5, had a mean difference in sub-ischial height from normal of-2.95 + 4.1 cms, which is statistically significant (t = -2.79, p=0.014), confirming the above deduction that girls are more severely affected. Their body size is significantly smaller than normal and this is not confined to spinal height. In this same study, spinal height was compared between normal family members, patients with operated and unoperated congenital vertebral anomalies. The details have been published elsewhere [4], and show significantly reduced spinal length only in those who had undergone spinal fusion, although, with the small numbers, it is possible that a true shortening even in unoperated spines was masked. 4. Discussion The common factor for both boys and girls is the observed failure of the growth spurt, with height at maturity being less than that anticipated from early growth pattern. Since patients were excluded from this study once they had had surgery, it can be due either to the spinal anomalies themselves or to a more general growth failure. While progression of the Cobb angle could also be a cause, these patients remained unoperated through their growth spurt, indicating a stable abnormality not requiring intervention in most cases. In the whole database, the age at surgery for boys was 7.5 ± 4.8 years, median 6.7, range 1.0 - 16.3; for girls, it was 8.9 ± 5.2 years (not statistically different) median 9.4, range 0.6 - 19.1. Surgery after age 11 years was carried out in 16 boys and 40 girls, i.e. significantly (p=0.03) more boys than girls had surgery well before their growth spurt. Again, from the whole data base, 53 patients with congenital vertebral anomalies presented after age 11 years, 40 girls of whom 11 had surgery and 13 boys of whom 4 have had surgery. The effect of the pubertal growth spurt on congenital spinal deformity is not clear: certainly it may cause progression of either the Cobb angle or the whole deformity, but there is not a simple cause-and-effect relationship between the two, although it would be much easier to understand if there were. Why girls should average a lower centile throughout childhood, while boys seem to run a normal trajectory, yet both drop towards the 10* percentile during puberty, without surgery or gross progression of Cobb angle, is not clear. Those who have

C.J. Goldberg ct ai /Growth Patterns in Patients

103

complained of short stature and been investigated in the endocrine unit, have not shown any identifiable hormonal defect. Thus it seems a combination of underlying anatomy, spinal surgery in some but not all cases, and general developmental failure have resulted in this phenomenon.

5. Conclusion Therapeutic implications are not immediately obvious. Surgery is indicated for a progressive spinal deformity, in the clear knowledge that this may reduce final stature. Maintenance of trunk balance seems preferable to a longer but crooked trunk. However, when an adolescent with congenital spinal anomaly complains of short stature, it would be unwise to reassure him that he has plenty of time to grow: the evidence suggests that he will not.

References 1. 2. 3. 4. 5. 6. 7.

Beals RK. Robbins JR. Rolfe B. (1993) Anomalies associated with vertebral malformations. Spine. 18(10):1,329-1,332. Cox LA. (1992) A guide to the measurement and assessment of growth in children. Castlemead Publications, Welwyn Garden City, Hertfordshire UK. Cunningham ML. Jerome JT. (1997) Linear growth characteristics of children with cleft lip and palate. The Journal of Pediatrics. 131 (5):707-711 Goldberg CJ. Moore DP. Fogarty EE. Dowling FE. Stature in patients with congenital vertebral anomaly. Spine. (In Press) Hoey HMCV. Cox LA. Tanner JM. (1986) The age of menarche in Irish girls. Irish Medical Journal. 79(10):283-285. Hoey HMCV. Tanner JM. Cox LA. (1987) Clinical growth standards for Irish children. Acta Paed. Scand. Supp 338. Moller AP. Swaddle JP. (1997) Asymmetry, developmental stability and evolution. Oxford University Press, Inc. New York.

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Th.B.GnvasiEd.i Research into Spinal Deformities 4 !OS Press. 20<>2

Morphometric characteristics of the thoracic and lumbar pedicles in the Greek population A.Christodoulou, T.Apostolou, I.Terzidis Hippokratio General Hospital.Orthopaedic Department., Thessaloniki, Greece. Director: Ass. Prof. A Christodoulou. Abstract. Objectives: To measure the dimensions of the pedicles of Tl to L5 in the Greek population. Methods:A total of 12 whole human cadaver spines were evaluated regarding pedicle dimensions (5 women and 7 men). The mean age at the time of death was 69,6 (range 62 to 84 years). The transverse and sagittal out side pedicle isthmus widths, the internal transverse diameter and cortex width were measured with electronic calipers both on the right and left pedicles. The data collected were statistically analyzed with the t- test. Results .The widest transverse diameter was at the LS level with a mean of 11,3mm (range 7,55-15,46mm). The narrowest transverse diameter was at the T5 level with a mean of 5,37mm (range 4,10 - 6,88mm). The widest sagittal diameter was at the Tl 1 level with a mean of 17,23mm (range 14,84-19,57mm), while the narrowest one was at Tl level with a mean of 9,1mm (range 7,1811,37mm). The maximum internal transverse diameter was at the L4 level with a mean of 8,26 mm (range 7,10-9,23mm) while the minimum was at the T5 level with a mean of 3,9mm (range 3,14-4,78mm). The maximum cortex width was at the L5 level with a mean of 2,55mm (range 2,15-3,02mm) and the minimum at the T5 level with a mean of 1,30mm (range 0,40-2,10mm). Conclusions:Prom the statistic analysis of the above data it was found that regarding the internal diameter there was statistically significant difference between males and females especially at T3, T7, T8 and L3 levels (P<0,05), and almost in all levels regarding the cortex width. There was also statistically significant difference between right and left pedicles regarding the transverse and the sagittal widths (P<0,05). The narrowest pedicle was at the T5 level and the widest was at the L5.

1. Introduction The evolution of the posterior techniques and the instrumentation systems for the treatment of fractures, deformities or degenerative diseases of the spine have lead from the laminar hooks -rods and wires-rods to the transpedicular screws-rods. The advantages of the latest are the control of the three columns of the spine with perhaps the need of less fusion levels and their application without spinal canal invasion. Knowledge of the morphology of the pedicle is therefore essential for the use of pedicle screws. Although most of the instrumentations in use for adults include screws of 5mm, 6mm, 7mm and 8mm of diameter and theoretically are suitable for the majority of the western- European population, it is of great interest if the available screws are suitable for the Greek population.

A. Christodoulou et al. /Morphometric Characteristics

105

This study was carried out to obtain a detailed knowledge of the pedicle morphology and the variations of it so that screws can be inserted safely, especially in the thoracic spine. 2. Material and Methods A total of 12 whole adult cadaver spines obtained from the National cemetery of Thessaloniki were evaluated regarding pedicle dimensions. There were 7 male and 5 female spines and the mean age at the time of natural death was 69,6 years (range 62 to 84 years). All the measurements were performed using Vernier electronic calipers both on the right and left pedicles. Measurements included pedicle transverse and sagittal outside widths at the narrowest diameter (isthmus). At this level of the isthmus an osteotomy was performed with a fine handicraft saw. Measurements also included the internal transverse diameter and the pedicle cortex width. The data collected were statistically analyzed with the student t-test. 3. Results Outside Transverse Diameter The widest transverse outside diameter of the pedicle was at L5 level with a mean of 11,30 mm (range 7,55-15,46mm). The narrowest transverse diameter was at T5 level with a mean of 5,35mm (range 4,10-6,88). Caudally to Tl 1 the minimum transverse outside diameter was larger than 7mm. Outside Sagittal Diameter The widest sagittal outside diameter was the Til level with a mean of 17,23mm (range 14,84-19,57mm) while the narrowest one was at Tl level with a mean of 9,14mm (range 7,18-11,37mm). At all levels the sagittal outside diameter was larger than 7mm. Internal Transverse Diameter

Table 1. The transverse out side pedicle isthmus widths

106

A. Chrisiodoiilou ct al. / Morphumetric Characteristics

Table 2. The sagittal out side pedicle isthmus widths

The maximum internal transverse diameter was at the L4 level with a mean of 8,26mm (range 7,10-9,23mm) while the minimum was at T5 level with a mean of 3,99mm (range 3,14-4,78mm). The minimum internal transverse diameter was larger than 6mm only at Tl 1 levelandatL3,L4,L5.

Table 3. The internal transverse diameter

Cortex Width The maximum cortex width was at L5 level with a mean of 2,55 (range 2,15-3,02mm) and the minimum at T5 level with a mean of 1,30mm (range 0,40-2,10mm) Comparison of the Results Between Males and Females

A. Christodoulou et at. / Morphometric Characteristics

107

Table 4. The cortex width.

From the analysis of the above data collected, statistically significant difference was found between males and females regarding: 1. The transverse outside pedicle width at T4 (p<0.05) and T6, T7,T8,T9,T11,T12, L1,L2,L3,L4,L5 (p<0.01) vertebrae 2. The sagittal outside pedicle width at Tl T2 T3 T5, T6 (p<0.05) T8,T9,T11,T12, L1,L2,L3,L4,L5 (p<0.01) vertebrae 3. The internal transverse diameter at T3 T7 T8 L3 and L4 vertebrae (p<0.05) 4. The cortex width at T3, T4, T8, Tl 1, T12, L3, L4 and L5 (p<0.05) In all measurements the mean dimensions were bigger in males Between Right and Left Pedicles Statistical significant difference (p< 0.05) was found between right and left pedicles regarding 1. The transverse outside pedicle width at T3 and T4 vertebrae 2. The sagittal outiside pedicle width at T3 and T4 vertebrae 3. The internal transverse diameter at T2, T3 and T4 vertebrae 4. The cortex width at T4, T5 and T7 vertebrae The above differences did not only appear in the right or left side, but they were mixed up. 4. Discussion The recent increased interest in internal fixation of the spine and the worldwide use of pedicle screw fixation systems establish the knowledge of the pedicle size of the population involved very crucial for safe application of these systems, therefore many authors have reported on this subject1)2'3-5'6. One of the main factors regarding the rigidity of fixation systems is the pull out strength of the transpedicular screw7. As the results have shown that a 1mm increase in screw diameter increases the pullout strength of the screw4'7, it is evident that the wider the screw the better the fixation. Therefore the outer screw diameter should match precisely the internal transverse diameter of the pedicle without exceeding at any circumstances the outside transverse one. From our study one may assume that in Greek population the narrower transverse outside pedicle width is at T3, T4, T5 and T6 levels and the same is found with regard to the internal transverse diameter. From these results, considering that the female pedicles are smaller with regard to the crucial diameters (transverse outside and internal) for screw application, a preoperative CT assessment may be necessary for the above levels and screws of less than 5mm diameter may be needed occasionally or they should not be used at all.

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A. Christodoulou ct al. /Morphometric Characteristics

Comparing our results of the transverse outside pedicle width with other authors reports there were significant differences with Zindrick's et al8 report at T5 and L5 (mean difference 4mm and 6,7mm respectively). There were differences at LI and L2 levels in coparison with the results of the Hou and Berry, the Greek pedicles being wider by an average of 2mm. Weinstein et al6 reported a 40% failure rate when attempting screw insertion in the upper lumbar spine with a 7,0mm screw. According to our results screws of 7,0mm can safely be inserted caudally in the T12 level, because the minimum transverse outside diameter exceeded 7 mm by more than 1 mm. We disagree with the conclusion of Kim et al3 that insertion of a 6mm screw is dangerous in the upper lumbar spine. As the minimum mean internal transverse diameter is more than 6mm the tap or a self tapping screw should be used which can cut the negative helix into the cortex. The sagittal outside pedicle widths were never found to be smaller that 7mm and were always greater than the transverse widths. Regarding the population which was studied 5mm diameter screw may safely be inserted at the levels of Tl, T2 and T9, 7mm diameter screw at T12 and the caudally levels down to L5. The risky levels are at T3, T4, T5, T6, T7 and T8 which in females should be measured by CT. 5. Conclusions Pedicle widths appear to have differences between various populations. Measurements should be undertaken in different continents or even in different groups of population by the local spinal surgeons. In the Greek population screws of 7mm may be used caudally to T12 vertebrae with the use of the tap. Pedicles of critical levels in the midthoracic spine should be measured preoperatively by CT methods. References 1. 2.

3. 4. 5. 6.

7.

8.

Berry JL, Moran J.M, Berg WS, Steffee A.D. A morphometric study of human lumbar and selected thoracic ertebrae Spine 1987; 12 (4): 362-367. Krag M.H, Beynnon B.D., Pope M.H., Frymoyer J.W., Haugh L.D., and Weaver D.L>, An internal fixator for posterior application to short segments of the thoracic, lumbar, or lumbvosacral spine: Design and testing. Clin Orth. 203:75 1986. Nam-Hyun Kim, Hwan-Mo Lee, In-Hyuk Chung, Ho-Jeong Kim, Sang-Jm Kim. Morphometric study of the pedicles of thoracic and lumbar vertebrae in Koreans. Spine 1999; 19(12)1390-1394. Scoles RV, Linton AE, Latimer B, Levy ME, Digiovanni B.F. Vertebral body and posterior element morphology: The normal spine in middle life. Spine 1988; 13:1082-1086. Shuyun Hou, Rishard Hu, Yamin Shi. Pedicle morphology of the lower thoracic and lumbar spine in a Chinese Population. Spine 1999; 18(3): 1850-1855. Wittenberg R.H, Lee S.K, Shea M, White A.A, Hayes C.W. Effect of screw Diameter, Insertion Technique and Bone Cement Augmentation of Pedicular Screw Fixation Strength. Clin. Orth 1993; 296:278-287. Weinstein Jn, Spraft KF, Spengler D, Black C, Reid S. Spinal pedicle fixation: reliability and avlidity of roentgenogram-based assessment and surgical factors on successful screw placement: spinel988,I3(9):l012-18. Zindrick MR, Wiltse LL, Doornik A et al. analysis of the Morphometric characteristics of the thoracic and lumbar pedicles. Spine 1987; 12(2): 160-166

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Does Coralline Hydroxyapatite Conduct Fusion in Instrumented Posterior Spine Fusion? Panagiotis Korovessis, Maria Repanti, Georgios Koureas Orthopaedic Department, General Hospital "Agios Andreas ", 26224 Patras, Greece Fax :0030-61-361596, E-mail: [email protected] Abstract Objectives. This study was conducted to investigate the course of incorporation of coralline hydroxyapatite in human spine. Summary of Background data. Conventional techniques for surgical treatment of spine have a substantial failure rate and associated morbidity. Bone graft substitutes are an alternative technique to enhance fusion rates and limit the morbidity associated with spine fusion using autologous iliac crest bone graft. There are some experimental studies supporting the use of hydroxyapatite in spine surgery. Material & Methods. During revision surgery specimens derived from the fusion mass from 15 operations in 13 patients, who received spinal instrumentation and fusion in cervical, thoracic, and lumbar spine and addition of coralline hydroxyapatite. The age of patients at the time of revision surgery was 46+20 years. The time lapsed from the implantation of coralline hydroxyapatite and revision surgery was 11+9 months. The indication for revision surgery was infection, pseudarthrosis, technical error, and pain related to bulky hardware. The diagnosis for the primary fusion was degenerative disease, trauma and scoliosis, and the material of instrumentation used was composed from titanium alloy. The coralline hydroxyapatite was applied on the decorticated posterior elements of the instrumented spine. Material from ten different places from the fusion mass was intraoperatively taken in all patients and was sent for histological evaluation using the Hematoxylin-eosin histological stain technique and photomicroscope. Results: Under photomicroscope there was a remarkable concentration of foreign-body like giant cells & development of inflammatory granulation tissue around hydroxyapatite, which was gradually replaced by dense connective collagen tissue. Both inflammatory granulation and collagen tissue showed areas with foreign body reaction. In the cases, where bone has developed, the most initial finding was the presence of osteoblasts & apposition of osteoid in contact to hydroxyapatite granules. In a later phase, cancellous and lamellar bone has developed as a result of secondary ossification. Bone formation was observed in 11/15 cases and was related with the patient's age in favor of young patients (R=0.56, P<0.05), while there was no correlation with time lapsed from operation. Conclusion: Coralline hydroxyapatite conducts bone formation in spine surgery because in the vast majority of the operated cases for different spinal disorders bone and osteoid has developed around the implanted coralline hydroxyapatite.

1. Introduction The rate of failure to obtain a solid spine bony fusion may be as high as 45% and the incidence of morbidity associated with autogenous iliac crest bone graft harvest may approach 30% [1,2]. Ceramics, including sea coral, have been investigated as potential bone

I in

P. Korovcssis ct nl. /Docs Coralline H\(lro\\apaliti< Conduct Fusion'.'

Figure 1: Granulation tissue comprising foreign body giant cells and newly formed collagen around coralline hydroxyapatite (CH) granules, which look like empty spaces following tissue processing (He X 100).

Figure 2 : Osteoblasts rimming osteoid (O) apposition and development of cancellous bone in the connective tissue surrounding hydroxyapatite granules (HEX 100).

Figure 3 : Well-formed cancellous bone (B) spicules . The position of hydroxyapatite granules is shown with arrow. ( HE X 100).

P. Komvexxix et al. /Docs Coralline Hydroxyapcttitc Conduct Fusion':

substitutes [3,4,5]. Natural sea coral comprised of calcium carbonate has been used in anterior and posterior spine fusions [3,4,5]. Coralline hydroxyapatite served as an excellent carrier for the bovine osteconductive bone protein extract yielding superior results to those obtained with autograft or bone marrow [6]. The purpose of this study was to investigate the histological course of incorporation of coralline hydroxyapatite in posterior and posterolateral instrumented spine fusion

2. Material and Methods Coralline hydroxyapatite (Pro Osteon 500; Interpore International, Irvine, CA, USA) was used in granules of 2-5 mm diameter. Intraoperatively, autogenous blood was mixed with the coralline hydroxyapatite granules and the resulted mixture was applied on the posterior decorticated elements of the instrumented spine. The diagnosis for primary operation was degenerative lumbar disease, spine trauma, idiopathic scoliosis. The instrumentation CDHorizon (Sofamor-Danek) that was used was composed of titanium alloy. The age of the patients at the time of revision surgery was 46 + 20 years, (range 16 to 78 years). The time lapsed between the two surgeries was 11 ± 9 months (Table 1). The indications for revision surgery are shown in Table 1. Material from 10 different areas within the spine fusion mass was intraoperatively taken during the revision surgery and was sent for histological evaluation with photomicroscope and Hematoxylin-Eosin stain technique. The presence of bone surrounding coralline hydroxyapatite granules was graded as (0) when absence of bone, (+) as mild presence of bone, and (++) as strong evidence of bone. Statistical analysis was performed using the Pearson Correlation Coefficient (r).

3. Results The specific histologic picture was a concentration of "foreign-body" like giant cells around the hydroxyapatite granules, associated with development of inflammatory granulation tissue, which was gradually replaced by dense collagen tissue with the time lapsed from initial operation. Both inflammatory granulation and collagen tissues showed areas with foreign body reaction (Figure 1). In the cases, where bone has developed the first initial finding was the presence of osteoblasts & apposition of osteoid close to the hydroxyapatite granules (Figure 2). In a later phase, it has developed cancellous or cortical bone, that seems to be the result of intercartilaginous ossification (Figure 3). Bone formation was observed in 11/15 cases and it was related with the age in favor of young patients (R=0.56, PO.05). The presence of infection in this series, does not seem to affect bone formation around hydroxyapatite granules. All patients' and histological data are summarized in the Table 1. 4. Discussion Currently autogenous iliac bone graft is the gold standard with which all graft alternatives are compared. This study was conducted to determine if coralline hydroxyapatite conducts bone formation "in vivo" in posterior spine fusion in human beings and showed that

Hi s t o i o g i c a I

Time (days) No

Age

1 ' ' GO

Gender

Diagnosis for

Levels of

f i r s t operation

F

degenerative stenosis

Diagnosis for

between

Osteoblasts &

instrumentation

revision

surgeries

osteoid

L1-L5

deep infection

30

No

Bone

No

findings

radio-

Synovial

Metal

graphic

membrane

debris

fusion'"

-t

2

78

F

T12, L1 fracture

T10-L4

bulky hardware

150

+

3

65

M

degenerative L4-L5

L4 & L5

subcutaneous serorna

40

-

•I

55

M

facture/dislocation C6-C7

C5-Th2

bulky hardware

360

+

-

5

57

M

lumbar spinal stenosis

L4-S1

deep infection

30

(>

29'

F

superficial infection

45

44

t-

4

29'

F

L3-fracture L3-fracture

L2-L4

7

L2-L4

infection

60

44

4-

8

56

F

lumbar spinal stenosis

L2-L5

adiacent segment degeneration

360

44

++

9

23

F

L4, L5 fracture

L3-S1

4

10

25

F

Idiopathic Scoliosis

Th10-L5

bulky hardware

540

4

11

-16

F

mstabilty L4-L5

L4-L5

adjacent segment degeneration

360

4

Yes

12

30

F

osteoid osteom T12 pedicle

Th12-L1

bulky hardware

720

4*

Yes

13

16

M

Idiopathic Scoliosis King I

TM12-L4

progression unfused curve

720

4

1 -1

70

M

Thl2-fracture

T10-L2

bulky hardware

90

I'."

63

F

degenerative lumbar disease

L2-L5

bulky hardware

1080

deep

infection

42

-

Yes

4

4-t

Yes

i

4-

Yes

• *

4

Yes

•t .

Yes N

o

P. Korovessis el al. /Does Coralline Hydroxyapatite Conduct Fusion?

\ \3

indeed coralline hydroxyapatite conducts bone formation within the fusion mass in any region of the spine independently from the diagnosis for primary operation, in 73% of the cases and as early as six weeks postoperatively. Although in animals [6,7] coralline hydroxyapatite alone is not sufficient osteogenic for spine fusion, this study showed osteoid and bone formation. One potential limitation of the current study was only 11 from the 15 cases had follow up more than 6 months a minimal time for solid fusion and thus such an analysis was not possible. However, it is possible, as seen in other models, that ingrowth into coral may have increased gradually for up to one year postoperatively [8]. Thalgott [9] radiologically studied the incorporation of coralline hydroxyapatite, used in cervical spine for anterior interbody fusion with rigid anterior platting and showed a 100% incorporation rate. This study showed that coralline hydroxyapatite was useful when used as an osteoconductive graft substitute in posterior and posterolateral instrumented fusion in human beings, with different pathologies, patients' age and spine region. A possible limitation of this study was that all revision operations were made because of complications after surgery, some of them were related to fusion. However, revision operation were otherwise ethical not possible. This histological study on human beings supports the use of coralline hydroxyapatite in spine surgery. This method avoids the use of autogenous iliac bone graft and theoretically reduces related donor site complications and the increased morbidity associated with harvesting iliac crest bone, but it is however cost effective. 5. Acknowledgments The authors wish to express their appreciation to Mr Georgios Korovessis Computer Science, University of loannina for his assistance in statistical analysis of this manuscript. References 1 2. 3.

4. 5. 6. 7. 8. 9.

Arrington ED, Smith WJ, Chambers HG, Bucknell AL, Davino NA. Complications of iliac crest bone graft harvesting. Clin Orthop 329 (1996) 300-9. Banwart JC, Asher MA, Hassanein RS. Iliac crest bone graft harvest donor site morbidity. A statistical evaluation. Spine 20 (1995) 1055-60. Guigui P, Plais PY, Flautre B, et al. Experimental model of posterolateral spinal arthrodesis in sheep. Part 2. Application of the Model: Evaluation of vertebral fusion obtained with coral (Porites) or with a biphasic ceramic (Triosite). Spine 19( 1994) 2798-803. Korovessis P, Z.Papazisis, G.Petsinis. Unilateral psoas abscess following posterior transpedicular stabilization of the lumbar spine. Eur Spine J 9( 2000) 588-90. Rahimi F, Maurer BT, Enzweiler MG. Coralline hydroxyapatite: A bone graft alternative in foot and ankle surgery. J Foot Ankle Surg 36 (1997) 192-203. Boden SD, Martin JG, Morone M, Ugbo JL, Titus L, Mutton CW. The use of coralline hydroxyapatite with bone marrow, autogenous bone graft, or osteoinductive bone protein wxtract for posterolateral lumbar spine fusion. Spine 24 (1999) 320-327. Feiertag MF, Boden SD, Schimandle JH, Norman JT. A rabbit model for nonunion of lumbar intertransverse process spine arthrodesis. Spine 21 (1996) 27-31. Kuhne JH, Bartl R, Frisch B, Hammer C, Jansson V, Zimmer M. Bone formation in coralline hydroxyapatite. Effects of pore size studied in rabbits. Acta Orthop Scand 65 (1994)246-52. Thalgott JS, Fritts K, Giuffre JM, Timlin M. Anterior interbody fusion of the cervical spine with coralline hydroxyapatite. Spine 24 (1999) 1295-1304.

1 14

Th.B. GVm/.vi A W ; RcM'arcli into Spinal f)ti<>rnutu .•* 4 IdS Pi i w 2»ti2

The Effects of Mechanical Loading on the mRNA Expression of Growth-Plate Cells Villemure I., Chung M.A., Seek CS., Kimm M.H., Matyas J.R., Duncan N.A. The McCaig Centre, The University of Calgary, Faculty of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta, T2N4N1, Canada Abstract: Bone growth is a complex process involving proliferation, maturation and hypertrophy of chondrocytes in the growth plates. Mechanical forces applied to growing bones alter their longitudinal growth. However, the mechanisms by which chondrocytes modulate longitudinal bone growth are not well understood. This in vitro study investigated the effects of mechanical loading on the mRNA expression pattern of key molecular components of the growth-plate. Short-term static loading was applied to rat proximal tibial growth-plate explants. Various age groups at specific developmental stages were investigated. In situ hybridization was used to assess the mRNA expression of the cells in different zones of the growth-plate. Four key components were investigated: 18s (basic cell metabolism), type II collagen (major extracellular matrix component), type X collagen (matrix component in hypertrophic zone) and PTH-PTHrP receptors (pre-hypertrophic chondrocytes). The spatial variation in the mRNA expression between loaded explants and their contralateral controls was compared to establish: - the sensitivity of the different growth-plate zones to mechanical loading; - the sensitivity of the different developmental stages to loading. Preliminary results indicated that static loading on the growth plate of 80 d.o. rats affects type II and X collagen gene expressions while PTH-PTHrP remains insensitive to static loading. Improved understanding of growthplate mechanics and the underlying biology is required to provide a scientific basis for the treatment of progressive deformities.

1. Introduction and objectives Longitudinal bone growth occurs in the cartilaginous growth plates, which contain columns of chondrocytes as their functional units [1]. Within growth plates, a complex biological process involving temporo-spatial progression of chondrocytes operates throughout three different zones: the reserve zone, the proliferative zone and the hypertrophic zone (Fig.2). The growth rate of a bone is a complex interplay between: 1) cell replication in the proliferative zone; 2) cell enlargement in the hypertrophic zone; and 3) matrix synthesis throughout the growth-plate as well as controlled matrix degradation at the chondro-osseous junction [1,2,3]. Mechanical forces applied statically to growing bones alter their longitudinal growth, where increased pressure on the plates retards growth and reduced pressure accelerates growth [3,4,5]. However, the mechanisms by which chondrocytes modulate longitudinal bone growth are not well understood and very little is currently known about the biological response of these cells to load [1]. This in vitro study investigated the effects of mechanical loading on the mRNA expression pattern of key molecular components of the growth-plate using an explant model.

/. Villemure et al. / The Effects of Mechanical Loading on the inRNA Expression

1 15

2. Material and Methods 2.1 Animal model, tissue processing and experimental setup Tibiae were freshly isolated from 6 female Sprague-Dawley rats of each age group 21 (weaning), 35 (pubertal growth spurt), 56 (mid-puberty) and 80 (mature stage) days old. Epiphyseal bone/growth-plate/metaphyseal bone plugs of 3.50±0.01 mm in thickness were sectioned from the proximal tibial ends parallel to the growth plates using a diamond wafer saw (Fig.l). A loaded explant from each rat was paired to its contralateral unloaded control. Each plug was sectioned through the bone sagittal plane into two equal-sized halves in order to minimize cell death during incubation time of this metabolically active tissue. Following several washes, two complementary half plugs were placed side by side into a disposable petri plate, and confined along the bone longitudinal axis between two ceramic porous plates of 6 mm thick and 51 Jim pore diameter (Fig.l). For loaded explants, a cylindrical aluminum bucket filled with copper bullets was placed onto the upper ceramic plate and served as static loading, with magnitude fixed at 55% of the rat body weight (Fig.l). Unloaded and loaded explants were incubated in Dulbecco's Modified Eagle Medium (DMEM-F12) supplemented with 10% fetal bovine serum and 1% pen/strep&fungizone for 24 hours at 37°C under an atmosphere of 95% O2 and 5% CO2.

Fig.l Experimental setup

2.2 In situ hybridization In situ hybridization techniques were used to assess the mRNA expression of the cells in different zones of the growth-plate. Four key components were investigated: 18s (marker of basic cell metabolism), type II collagen (marker of major extracellular matrix component), type X collagen (marker of hypertrophic chondrocytes) and PTH-PTHrP receptors (marker of pre-hypertrophic chondrocytes). Following incubation, explants were fixed in 4% paraformaldehyde, decalcified in 10% ethylenediaminetetraaceitc acid (EDTA), dehydrated and embedded in paraffin. Sections were cut at a thickness of 6 p.m and mounted on Superfrost Plus slides. Normal explants, consisting of plugs fixed and embedded immediately following dissection without incubation, were also processed to assess the effects of the incubation procedure when comparing with the culture control explants. In situ hybridization was basically performed as described in Alvarez et al. (2000) [6]. In short, rehydrated sections were postfixed, and hybridized with 400ng/ml of DIG-labeled probe (no prehybridization step). Hybridized probe was detected with the alkaline phosphatase-coupled anti-DIG antibody and revealed with a solution containing BCIP (5-bromo-4-chloro-3-indolyphosphate) and NET (nitroblue tetrazolium). Negative controls were subjected to the identical procedure without addition of probe. No positive signal was found in these negative controls. Competitive in situ hybridization was also completed on normal explants using unlabeled and DIG labeled 18s probes, and obtained signals confirmed probe specificity. The spatial variation in the mRNA expression between loaded explants and their contralateral unloaded controls was compared to establish the sensitivity of: 1) the different growth-plate zones to loading; 2) the different developmental stages to loading.

116

/. Villemnre ft til. / The Effects of Mechanical Loading on the mKNA Expression

3. Results Results are presented for rat pubertal growth spurt (35 d.o.) and mature stage (80 d.o.). Mean body weights were 143.3±8.1 g (35 d.o.) and 251.8±20.0g (80 d.o.). Corresponding static loading applied along the direction of longitudinal growth reached on average 0.77±0.04 N and 1.3610.11 N and resulted in mean stresses of 19.512.0 kPa and 29.814.1 kPa. Growth plate sections showed typical columnar arrangement of chondrocytes traveling successively from the reserve zone (R), consisting of stem cells relatively unoriented, the proliferative zone (P), characterized by highly organized cells undergoing frequent mitosis, and the hypertrophic zone (H), composed of cells arranged in a columnar pattern and undergoing rapid increase in height and volume (Fig.2).

Fig.2 Typical section of a rat (35 d.o.) proximal tibia) growth plate showing the different zones.

In normal explants, 18s signal was distributed homogeneously throughout the growth plate cells, indicating normal basic cell metabolism following tissue processing (Fig.3). Type II collagen synthesis of variable intensity was observed in all growth plate zones and type X collagen mRNA was primarily confined to the hypertrophic zone (Fig.3). These in situ expressions are in agreement with results from other studies [6]. Staining of PTH-PTHrP receptors was predominantly positioned in the pre-hypertrophic zone, indicating cellular activity at the junction of proliferative and hypertrophic zones (Fig.3). Comparison of 80 d.o. culture control and normal explants confirmed that the incubation procedure did not affect normal basic cell metabolism, type II and X collagen syntheses as well as PTH-PTHrP receptor activity of the growth plates (Fig.3). At 35 d.o., a diminished signal was observed for cell metabolism (18s).

Fig_3 In situ hybridization with 18s, collagens type n and X as well as PTH-PTHrP receptors for the normal, culture control and loaded explants obtained from 80 d.o, rat growth plates.

/. Villemure el al. / The Effects of Mechanical Loading on the mRNA Expression

\}7

In 80 d.o. loaded explants, 18s signal was expressed throughout the growth plate zones similarly to normal and culture control explants, indicating that static loading did not perturb the basic metabolism of chondrocytes and that cell viability was preserved throughout the experiment (Fig.3). The expression pattern of type II collagen showed a reduced staining band compared to culture controls in four of the six rats (Fig.3). Type X collagen mRNA also indicated a thinning of the expression band in the hypertrophic zone in all six loaded explants (Fig.3). No difference was observed between loaded and culture control explants for PTHPTHrP receptor mRNA (Fig.3). In 35 d.o. loaded explants, a deficit of 18s staining was observed in the central portion of growth plates, suggesting a disruption of normal basic cellular metabolism and cell death due to loading. A similar reduced expression was observed for collagens and PTH-PTHrP mRNA. More investigation is required to assess the effects of static loading on cell viability and on the biomarkers in the outer regions of the 35 d.o. rat growth plates. 4. Discussion Preliminary results indicate that type II and type X collagen genes are sensitive to static loading on the growth plate, which would target the hypertrophic zone as a key player in growth alteration. On the other hand, static loading does not affect PTH-PTHrP receptor mRNA, suggesting that the passage from the proliferative to the hypertrophic zone would not be involved in short term static loading. More investigation is required to better explain the underlying biomechanical differences between the responses of 35 d.o. and 80 d.o. rat growth plates to load. Limits of this study include the in vitro environment of the experimental model compared to an in vivo approach. Future processing of developmental stages 21 and 56 d.o. will provide a more complete mechano-biological portrait of the effects of mechanical loading on these mRNA expression patterns. Improved understanding of growth-plate mechanics and the underlying biology is required to provide a scientific basis for the treatment of progressive deformities such as adolescent idiopathic scoliosis. 5. Acknowledgements This research project was funded by the Natural Sciences and Engineering Research Council of Canada and the Alberta Heritage Foundation for Medical Research. Collagen probes were kindly provided by Drs B. Olsen (Harvard Medical School, Boston) and S.S. Apte (Lemer Research Institute, Cleveland) and the PTH-PTHrP receptor probe was a gift from Drs H. Kronenberg and U. Chung (Massachusetts General Hospital, Boston). References 1. 2. 3.

4.

Hunziker EB, Schenk RK (1989), Physiological mechanisms adopted by chondrocytes in regulating longitudinal bone growth in rats, J Physiol, 414, 55-71. Wilsman NJ, Farnum CE, Green EM, Lieferman EM, Clayton MK (1996), Cell cycle analysis of proliferative zone chondrocytes in growth plates elongating at different rates, J Orthop Res, 14, 562-72. Farnum CE, Nixon A, Lee AO, Kwan DT, Belanger L, Wilsman NJ (2000), Quantitative threedimensional analysis of chondrocytic kinetic responses to short-term stapling of the rat proximal tibial growth plate, Cells Tissues Organs, 167,247-258. Alberty A, Peltonen J, Ritsila V (1993), Effects of distraction and compression on proliferation of growth plate chondrocytes, A study in rabbits, Acta Orthop Scand, 64,449-55.

118

5 6.

/. Villemurc ct al. / The Effects of Mechanical Loading on the mRNA Expression

Stokes IAF, Aronsson D, Urban JPG (1994), Biomechanical factors influencing progression of angular skeletal deformities during growth, EwJExp Musculoskel Res, 3, 51-60. Alvarez J, Balbin M, Santos F, Fernandez M, Ferrando S, Lopez JM (2000), Different bone growth rates are associated with changes in the expression pattern of types II and X collagens and collagenase 3 in proximal growth plates of the rat tibia, J Bone Miner Res, 15, 82-94.

Tli.B.Grmix(E(l.) Research into Spinal Deformities 4 IOS Prexx. 2002

119

Back Shape Assessment in each of Three Positions in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS): Evaluation of a 10-level Scoliometer Method Interpolated to 18-levels R. G. Bunvell, R. K. Aujla1, A. A. Cole1, A. S. Kirby1, R. K. Pratt1, J. K. Webb1 and A. Moulton2 1 2

The Centre for Spinal Studies and Surgery*, Queen's Medical Centre, Nottingham & Department of Orthopaedic Surgery, King's Mill Hospital, Mansfield, England

Abstract. A Scoliometer was used by one observer (RKP) to assess the reproducibility of angle of trunk inclinations (ATIs) in 13 preoperative patients with AIS (thoracic 7, thoracolumbar 6, mean Cobb angle 50 degrees, right 9, age 15.4 years, girls 10). Three positions were used namely standing forward-bending, (FB) sitting FB and prone. Readings of ATI on the back were obtained at each of 10 levels (Tl- SI). The subject was repositioned after walking around the room and a second set of readings obtained (repeats). All readings were converted by a computer program to 18 levels and plotted. The readings from 18 levels were analysed by level, as well as summated and averaged both without and with correction for the side of the curve. Conclusions. Back surface asymmetry measured with a Scoliometer in these preoperative patients with AIS is less in the prone position than in each of the forward bending positions. The standing FB position has the best reproducibility which supports the practice of using this position to measure Scoliometer ATIs in preoperative patients with AIS. "Supported by AO/ASIF Research Commission Project 96-W21

1. Introduction The standing-forward bending (FB) position is in general use for the detection and management of scoliosis but a few workers have evaluated two other positions namely the sitting-forward bending (FB) position and the prone position. In a school screening program for scoliosis Harada et al [6] using contour line photography reported that the sittting FB position is superior to the standing FB position for obtaining accurate hump height measurements. Upadhyay et al [9,10] measured back surface asymmetry and evaluated three standard positions - standing erect (ISIS), standing FB (Scoliometer) and sitting FB (Scoliometer) in 13 patients with AIS; using the Scoliometer differences were found between the standing and sitting positions which were used to devise methods to improve screening for scoliosis [2]. Scutt et al [7] using the Scoliometer in three positions (standing FB, sitting FB, prone) at each level from C7-S1 in 27 patients with AIS found advantages for the prone position. Grivas et al [5] using the Pruijs Scoliometer on 900 healthy schoolchildren examined back shape in each of the standing and sitting FB positions and recommended the latter as the standard position for measuring the rib or lumbar hump. Burwell et al [4] using the Scoliometer in 30 school screening referrals found that reproducibility is better in each of the sitting FB and prone positions than in the standing FB position. The better reproducibility of sitting FB ATIs was considered to it being a more stable position than is standing FB.

I 20

R.Ci. Biinvcll cl n/. /Hack Sluipe Assessment in Each r>f Three Posititms

Although there were clear advantages of the prone position it was not recommended for several reasons including the unknown effect of anterior ribcage asymmetry and plagiopelvy on posterior trunk asymmetry. Further research on back shape in the prone position was suggested on healthy and scoliotic subjects. This paper reports the use of a Scoliometer to evaluate the reproducibility of ATIs in 13 preoperative patients with adolescent idiopathic scoliosis (AIS) in each of three positions standing FB, sitting FB and prone. Readings of ATIs were recorded at 10 levels on the back. 2. Material and Methods 2.1 The patients and their spinal curves After informed consent from the parents/guardians 13 preoperative patients were included in the study (10 girls and 3 boys, mean age 15.4 years). The spinal curves were thoracic 7, thoracolumbar 6 with a mean Cobb angle of 50 degrees, right 9, left 4. 2.2 The three positions for the Scoliometer ATI readings Surface back shape was examined in each of three positions [4] using the Scoliometer down the back from T1-S1 by one observer (RKP). The skin on the subject's back was marked at ten equally spaced points between the vertebra prominens and the mid-sacral point (half way between the dimple of Venus). Scoliometer angle of trunk inclinations (ATIs) at each level were obtained in each of three positions (1) standing forward bending, (2) sitting forward bending, and (3) prone. In the standing FB position the feet are slightly apart and the hands together placed between the knees so that the subject is stable. In the sitting FB position the subject sits on a box 30 x 30 x 30 cm and bends forward, placing the shoulders between abducted hips with the arms hanging down and resting on the floor. In the prone position the subject lies on a hard couch with her forehead supported on a stand, the arms dependent and the anterior superior spines in contact with the couch [3,4]. Two sets of readings were obtained in each position with the subject moving around the room between each set of measurements (repeats). The 10-level Scoliometer data were converted to 18level ATI data using a computer program [3]. 2.3 Right humps are assigned positive values and left humps negative values In plotting the ATI data to provide a graphic representation, right humps were assigned positive values and left humps negative values (= sign for side). 2.4 Mean ATIs at each level A paired t-test was performed at each level without correcting the sign for side. 2.5 Summated and averaged ATIs without and with correction for side In the reproducibilty analyses for the repeats the sign for side was not corrected in calculating the mean average ATI of the 18 levels for each position (unless stated). To provide an overall descriptor of back shape at all the 18 levels the ATIs of humps on the left were made positive (i.e. corrected for side), summated and averaged to calculate a mean average ATI (and standard deviation) for each position. 2.6 Statistical analyses The 18-level Scoliometer ATIs were (1) compared for the three positions, and (2) analysed for reproducibility The statistical analyses included a paired t-test, variance (F) ratio, correlation coefficient, linear regression analysis with ANOVA to produce the residual mean square (and root mean square, rms) relative to the regression line, technical error of the measurement (TEM) and coefficient of reliability, /?[!!].

R.G. Burwell ct al. / Buck Shape Assessment in Each of Three Positions

\ 21

TEM is calculated as the square root of (the difference between ATI measurements squared/2 x number of patients measured) [11]. R is calculated as 1 - [TEM )2/(SD)2] where SD is the total inter-patient variance, including measurement error for the ATIs [11].

3. Results 3.1 Comparison between the three positions The mean average ATI in the prone position (5.5±1.4 degrees) is significantly less than in each of the standing FB position (7.1±1.9 degrees, P=0.006) and sitting FB position (6.7±1.8 degrees, P=0.035) (all first repeats). 3.2 Reproducibility of repeats 3.2.1 Graphic representation of ATIs by 18 levels shows a fairly good agreement between repeats for most subjects in each of the three positions. 3.2.2 A paired t-test at each of the 18 levels shows no statistically significant difference for the standing and sitting FB positions but does for the prone position (significant at 2/18 levels, Bonferroni corrections). The mean average ATIs show no significant difference between repeats for any of the three positions (with and without correction for side, paired ttests). 3.2.3 Linear regression analysis for each of the three positions correlate very highly significantly (r, standing FB 0.97, sitting FB 0.89, prone 0.95, each P< 0.001). 3.2.4 Residual mean squares are for standing FB 1.8 degrees sitting FB 5.2 degrees, and prone 1.9 degrees (root mean squares, rms ±1.3, ±2.3, ±1.4 respectively). A variance ratio (F) test shows a significantly lower scatter for each of standing FB and prone ATI data compared with sitting FB ATI data (each PO.05). 3.2.5 The TEM for standing FB is 1.1 degrees, sitting FB 1.8 degrees and prone 1.5 degrees. 3.2.6 The coefficient of reliability (R) for standing FB is 0.96, sitting FB 0.82, and prone 0.90. 4. Discussion Prone position. The overall back asymmetry measured as the mean average ATI in the prone position is significantly less than in each of the standing FB and sitting FB positions. This confirms both the observation of Scutt et al [7] and our finding for school screening referrals [4]. The diminished ATIs in the prone position may be due to 1) elimination of gravity, 2) an effect of anterior ribcage asymmetry and plagiopelvy rotating the spine when the patient lies on her front, and 3) the removal of any leg-length inequality from influencing back shape in the standing FB position [1,5]. The findings reported here showing positional differences for the prone position (3.2.2 paired t-tests) indicate that the prone position is unsuitable for measuring back shape asymmetry in preoperative patients with AIS which is in contrast to the suggestion of Scutt el al [7]. The sitting FB position in these preoperative patients with AIS is not confirmed as the preferred position for assessing back shape asymmetry as suggested by others [5,6]. This statement is supported by: 1) the variance ratio (F) test that shows a significantly higher scatter for the sitting FB ATI data compared with each of standing FB and prone ATI data; and 2) the higher TEM and lower coefficient of reliability (R) for the sitting FB position (1.8 degrees, 0.82) compared with the lower TEM and higher R for each of the standing FB position (1.1 degrees, 0.96) and prone position (1.5 degrees, 0.90).

1 22

R.G. Rurwell cr al. / Rack Shape Assessment in Each of Three Positions

The standing FB position has the best reproducibility which supports the practice of using this position to measure Scoliometer ATIs in preoperative patients with AIS. This conclusion is different from our finding for school screening patients in that the prone position provided the best reproducibilty although for various reasons the sitting FB position is preferred [4]. This difference may be due to the preoperative patients (1) having stiffer backs than do school screening referrals and (2) more readily taking up a similar repeat position in standing FB than do school screening patients with smaller spinal curves and less stiff backs. The effect of any leg-length inequality that might have influenced back shape asymmetry was not evaluated in these preoperative patients. The suggestion that in measuring back surface asymmetry in the standing FB position the arms should hang free [8] is not confirmed as in school screening referrals [4]. References 1. 2.

3.

4.

5.

6.

7.

8. 9.

10.

11.

R.G.Burwell et ai, Standardised trunk asymmetry scores: a study of back contour in healthy children. Journal of Bone and Joint Surgery 65B, 452-462, 1983. R.G.Burwell et ai, School screening for scoliosis: the multiple ATI system of back shape appraisal using the Scoliometer with observations on the sagittal declive angle. In, Surface Topography and Spinal Deformity. Proceedings of the 5th International Symposium September 29-October 1, 1988, H. Neugebauer, G. Windischbauer (eds.) pp 17-23, Stuttgart: Gustav Fischer Verlag, 1990. R.G. Burwell et ai. Evaluation of vertebral rotation by ultrasound for the early detection of adolescent idiopathic scoliosis. In, Research into Spinal Deformities 2. I.A.F. Stokes (ed.), pp 73-76, AmsterdanrlOS Press, 1999. R.G. Burwell et ai, The early detection of adolescent idiopathic scoliosis in three positions using the Scoliometer and real-time ultrasound: should the prone position also be used? In, Research into Spinal Deformities 3. A. Tanguy, B. Peuchot (eds.), AmsterdanrlOS Press, 2002. T.B. Grivas et ai, Study of the natural history of the back trunk shape by the use of Scoliometer in children aged 5-12 years. In, Research into Spinal Deformities 2. I.A.F. Stokes (ed.), pp 223-226. AmsterdanrlOS Press, 1999. Y. Harada et ai, The role of contour line photography using the light cutting method and Moire topography in school screening for scoliosis. In, Moire Fringe Topography and Spinal Deformity. Proceedings of an International Symposium. M. S. More land, M. H. Pope. G.W.D Armstrong (eds.) pp 113-121, New York:Pergamon Press, 1981. N.D. Scutt et ai. The relationship between surface and radiological deformity in adolescent idiopathic scoliosis: effect of change in body position. European Spine Journal 5:85-90. 1996. A.J. Stirling et ai. Screening for scoliosis: the problem of arm length. British Medical Journal 292:1305-1306, 1986. S.S. Upadhyay et ai, The Integrated Shape Imaging System (ISIS) and the Scoliometer for recording back shape in scoliosis. A reliability and comparative study revealing positional changes in back contour (hump dynamics). In, Surface Topography and Spinal Deformity. Proceedings of the 4th International Symposium September 27-30, 1986, Mont Sainte Marie, Quebec. I.A.F. Stokes, J.R. Pekelsky, M.S. Moreland (eds.) pp 233-248, Stuttgart: Gustav Fischer Verlag, 1987. S.S. Upadhyay et ai, Hump changes on forward flexion of the lumbar spine in patients with idiopathic scoliosis. A study using ISIS and the Scoliometer in two standard positions. Spine 13 (2): 146-151 1988. S.J. Ulijaszek, J.A. Lourie, Intra- and inter-observer error in anthropometric measurement. In, Anthropometry: the individual and the population. S.J. Ulijazek, C.G.N. Mascie-Taylor (eds.), Chapter 3, pp. 30-55, Cambridge University Press, 1994.

Th.B.GrivasfEcl.) Research into Spinal Deformities 4 IOS Press, 2002

123

The validity of clinical examination in adolescent spinal deformities Grosso C*, Negrini S*, Boniolo A*, Negrini AJE *Fondazione Don Gnocchi, ONLUS, IRCCS, Milano; Centra Scoliosi Vigevano (Italy) Abstract Study Design: retrospective study on the accuracy and reliability of two clinical tests for scoliosis in young patients. Aim: to evaluate the inter-observer reliability of three non-invasive clinical measurements: hump height (HH), axial trunk rotation (ATR), and distance of the spinous process from the plumb line (DP) in standing; to compare these results with the corresponding radiographic measurements, the Cobb angles (CA). Population: 116 patients, 78 females and 38 males; 410 examinations have been performed (144 patients with brace and 266 without). Methods: a database was created using the measurements of different clinical parameters obtained from two examiners that measured them independently and in the same conditions. The Cobb method has been used as a gold standard. Results: our results show a very high inter-rater reliability for HH and ATR measurements. The DP shows a different inter-rater reliability for the thoracic (C7) and lumbar (L3) spine, in both cases lower than that in the frontal plane; the ICC of the thoracolumbar DP (D12) was very low. The correlation with the radiographic value was weak.

1. Introduction The gold standard in scoliosis evaluation is the measurement of the Cobb angle, obtained from radiographs: these are bi-dimensional, and many authors propose that this fact leads physicians to underestimate the three-dimensional aspects of the deformity. The exposition to radiations for these young patients has as an effect a small but significant increase in neoplastic alterations, and for this reason radiographs should be reduced to the minimum. It is necessary to validate a non-invasive, easy and not expensive method [1]. It is possible to evaluate the aesthetic component with clinical instruments used directly on the patients, such as the Bunnel Angle of Trunk Rotation (ATR), the hump height (HH), or the distance from the plumb line (DP). Many studies evaluated the repeatability of some of these measurements, but always in clinical settings [1-6]. 2. Aim of the study To answer to a clinical question: inter-observer reliability, in a clinical everyday setting, of three non-invasive clinical measurements (hump height [HH], axial trunk rotation [ATR] and distance of the spinous processes from the plumb line [DP]); their correlation with the corresponding Cobb angle (CA), and the gold standard in scoliosis evaluation.

124

(" Gro.\s<> cr ai / The Validity of Clinical Examination

3. Methods The results of 410 clinical examinations, performed by two independent examiners between September 1996 and June 2001, on 116 patients (78 females and 38 males) with idiopathic adolescent scoliosis, hyperkyphosis or hyperlordosis, have been collected.

TABLE 1. Population. AGE Mean

Range

1SD

F

13,3

7-20

M

14,2

5-19

13,6

5-20

TOT

KYPHOSIS

SCOLIOSIS

LORDOSIS

Thoracic

Thoracolumbar

23

21,7±10,5

20,4±10,7

21,9*9,2

43±13,3

50.5*9,9

2,7

24,8±15,5

17,4±13

19,9±14,9

50,4±9.6

50,7+12,1

2,4

22,1±11,2

19,4±1U

2U±10,4

4S,9±124

50,6± 10,7

Lumbar

A rehabilitation physician and a physical therapist, working in the same rehabilitation centre, were involved in the study. At the beginning they used the same protocol of evaluation, even if it had never been verified later and even if it could slightly change with time. This represents a real everyday clinical situation. All patients underwent the two evaluations within a period of time of one month. The examiners took the measurements with the same devices and in the same setting. All parameters were measured twice for each subject and the worst value was reported on the case sheet. The intra-class correlation coefficient (ICC), the Kendall concordance coefficient and Friedman's test were used, where appropriate. In order to correlate anthropometric and radiographic measurements, when ICC and Kendall coefficient were greater than 75% and 40% respectively, the linear regression and Spearman's correlation coefficient were used. 4. Results Our results show a very high inter-observer reliability for the HH and ATR measurements. The error associated to the examiners is similar for the thoracic, thoracolumbar and lumbar measurements. The DP shows a different inter-observer reliability for the thoracic (C7) and lumbar (L3) spine, in both cases lower than in the frontal plane; the ICC of the thoracolumbar DP (D12) was very low. The evaluation error associated with DP measurements is similar for the thoracic and lumbar regions. The correlation with the radiographic values was low: according to our results, none of these surface clinical everyday measurements were able to describe the radiographic results. TABLE 2. Inter-observer repeatability. T: thoracic; TL: thoracolumbar, L: lumbar; HH: hump height.

Thoracic Thoracolumbar Lumbar

Hump Height Angle of Trunk Rotation Plumb Line 86% 91% 86% 69% 91% 89% 76% 90% 86%

C. G rosso et al. /The Validitv of Clinical Examination

TABLE 3. Correlation between anthropometric and radiographic measurements. T: thoracic; TL: thoracolumbar; L: lumbar; R2: Pearson's product-moment coefficient; E: evaluation error.

Hump Height Angle of Trunk Rotation Plumb Line T TL L T TL L T L R2 0,42 0,27 0,04 0,20 0,27 0,01 0,36 0,03 6,4 7,4 E 8,3 8,6 9,6 6,0 15,0 14,0 5. Discussion The previous results concerning the high repeatability of the ATR in a research setting were confirmed by our data obtained in everyday clinical practice. It was surprising for us to find that the HH, commonly considered not reliable, proved to be even better than the ATR. Nor ATR, HH and DP demonstrated to be correlated with CA, even if in the literature a correlation between ATR and CA has been reported [4]. These results were anyway expected, because both ATR and HH measure the rotation of the spine in the horizontal plane, while CA measures the lateral flexion in the frontal plane: presumably, there is no correlation between these measurements because they refer to different phenomena of the same pathology: scoliosis. The gold standard (radiograph) method remains the sine qua non, especially for therapeutic decisions, but surface measurements are useful for aesthetic evaluation and represent an important prognostic factor. Measurements of the HH and ATR are reliable and complementary to the gold standard. Interesting and similar were also the results on the sagittal plane, whose data in the literature are sparse [6].

References 1. 2. 3.

4. 5. 6.

T. Karachalios, J. Sofianos, N. Roidis, et al. Ten-Year Follow-Up Evaluation of a School Screening Program for Scoliosis. SPINE Vol. 24 Num. 22, pp 2318 -2324,1999. P.Cote, B.G. Kreitz et al., A Study of the Diagnostic Accuracy and Reliability of the Scoliometer and Adam's Forward Bend Test. SPINE Vol. 23 Num. 7, pp 796-803,1998. L. De Wilde, F. Plasschaert, H. Cattoir, D. Uyttendaele. Examination of the Back Using the Bunnell scoliometer in a Belgian School Population Around puberty. Acta Orthopaedica Belgica, 1998 Jun; Vol. 64 (2), pp 136-43 P.O. Korovessis, M.V. Stamatakis. Prediction of Scoliotic Cobb Angle With the Use of the Scoliometer. SPINE Vol. 21 Num. 14, pp. 1661-6,1996 L. E Amendt, K. L Ause-Ellias et al. Validity and reliability testing of the scoliometer. Physical Therapy Vol. 70, Num. 2, 1990. P. Korovessis, G. Petsinis, et al. Prediction of Thoracic Kyphosis Using the Debrunner Kyphometer. Journal of Spinal Disorders Vol. 14. No. 1. pp 67-72,2001.

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New Approach to Objective Diagnostics of Polyfiinctional Disorders of the Neuromuscular Regulation in Children with Various Forms of Spine Deformities G. P. Dmitrieva, M. Yu. Karganov, N. N. Khlebnikova, O. I. Kovaleva, M. I. Kozhevnikova, S. B. Landa, L. A. Noskin Institute of General Pathology, Russian Academy of Medical Sciences; Boarding School No. 76 for Children with Scoliosis, Moscow, Russia Abstract, A combination of two methodical approaches (parallel evaluation of the psychomotor function and metabolic shifts) was used in examination of children with scoliosis. We evaluated adaptation of children at the certain stage of the disease for prediction of its further course and correction of the treatment.

1. Introduction The degree of pathological burden of scoliotic spinal deformities is routinely determined using various morphometric methods based on evaluation of the type and severity of skeletal abnormalities. At the same time, in some cases spinal deformities represent compensatory changes in the musculoskeletal apparatus ensuring functional regulation of neuromuscular processes (NMP). In light of this it is important to evaluate the effects of various types of musculoskeletal deformities on the maintenance of NMP. They are the multicomponent and multilevel processes with complex intra- and intersystem relationships. Therefore, routine approaches used in orthopedic correction (parameters of visual-motor coordination, posture stability, coordination of movements, etc.) cannot solve the problem of detection of functional NMP sufficiency. We believe that the functional approaches proposed by us would strengthen the arsenal of current diagnostic methods. 2. Object and Methods The use of a computer-assisted complex of movement measurements (CMM) attracted our attention in this respect. This method is expressive, noninvasive, completely automated and adapted for children's clinics specialized in correction of spinal column deformities. It allows to quantitatively evaluate the parameters of muscle tone (separately for flexors and extensors), the degree of hemispheric asymmetry, efficiency of neuromuscular transmission under visual control (and without it) and auditory control, motor memory, smoothness and accuracy of movements, error of flexor and extensor correction. This approach provides better evaluation of NMP elements, i.e. it is capable of characterizing the state of basic functions of the brain. There are numerous reports on significant differences in functional asymmetry of the brain in human, children included. Of particular interest is strict correlation between the state of the musculoskeletal apparatus and hemispheric asymmetry. For instance, right-sided

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scoliosis is associated with increased dominance of the right hemisphere. This should be taken into account during correction and prophylaxis of scoliosis. We evaluated the role of imbalance in central regulation of the psychomotor function and possible contribution of this phenomenon into the pathogenesis of idiopathic scoliosis, a complex and highly prevalent in children pathology. Here we studied asymmetry of the psychomotor function (PMF) in children with scoliosis of I-IV stage (280 children aged 6-16 years) during periodic right and left arm movements (rotation of a level in a horizontal plane with elbow support). Evaluation of PMF consisted of 3 tests: periodic movements within angular sectors of 30° and 10° with and without visual control (tests 1 and 2) and evaluation of the time of response to light and acoustic stimuli (test 3). Nonparametric method (centile tables) used by us is based on comparison of the test parameter with the mean value for a specially composed group (age, sex, etc.). Ranking of the test parameters is based on the data of population studies with consideration of age and sex of the examinees using a "hypofunction-hyperfunction" scale. Thus the rank of each parameter by its prevalence in normal population and its correspondence to the level of functioning of the studied physiological system can be determined. 3. Results Here we analyzed only parameters reflecting the balance between the excitation and inhibition processes in the central nervous system and involved into direct regulation of the muscular apparatus. The data presented in Table 1 demonstrate the incidence of hyperfunction by the CE parameter (correction error for flexors and extensors) in healthy children and in patients with scoliosis. This parameter characterizes movement accuracy and is determined by the development of the motor systems, peculiarities of sensorimotor integration and inhibition in the CNS. The fact that the percentage of children with hyperfunctional shifts of CE among patients with scoliosis 2.5-3-fold surpassed the corresponding values in healthy children in all age groups suggests that the regulation of the muscular apparatus in scoliotic patients is considerably disturbed. The results of testing on the KID device showed that asymmetric functional shifts were 2-3-fold more often observed than symmetric disturbances. Table. 1. Incidence (%) of hyperfunctional sifts in parameter CE (correction error for flexors/extensors) in healthy children and patients with scoliosis.

Age 6-9 10-14 15-17

Healthy children 29 (N=125) (N=26) 30 25 (N=40)

Scoliosis (N=20) 90 (N=19) 89 69 (N=42)

Development of scoliosis is determined among other reasons by disturbed synthesis and metabolism of matrix proteins [1], in particular by activation of matrix metalloproteases, the enzymes contributing to degradation of the intervertebral disk components. A correlation was found between the content of metalloproteases and the degree of degenerative changes in the intervertebral disk [2] and activation of these enzymes in the presence of interleukin 1 [3]. Ample biochemical data were obtained in model experiments and on tissues removed during surgery, however these data are fragmentary and often contradictory. Development of an integral method for estimation of metabolic shifts is very important for evaluation of

1 28

C.P. Dmitrievei a (tl /.\V'n Approach to Objective

scoliosis severity, efficiency of treatment and probably for identification of risk groups. However, the data on concentrations of individual substances cannot be interpreted from the viewpoint of integral assessment of the homeostasis. At the same time, examination of native biological fluids, where intermolecular interactions are preserved, provides such a possibility. Laser correlation spectroscopy (LCS). This method allows to measure the size of subcellular particles and to evaluate their interrelations. LCS is based on recording of spectral characteristics of monochromatic coherent light scattered in a disperse system. For polydisperse systems, the size distribution functions can be estimated by methods of scattered light spectrum analysis and the obtained correlation function can be regularized. Further development of LCS led up to the creation of "semiotic classifier". The main idea of this "semiotic classifier" is based on the fact, that the formation of the pathological trace in human organism depends not only on the disease nature, but also on the interaction between sanogenetic mechanisms the organism, which impede of the fixation of the pathological trace defying by the ethyopathogenesis. This idea is now widely used in preventive medicine. It was shown that subfractional compositions of biological fluids could characterize the symptomatic complex of organism status. Indeed, changes in high-molecular-weight components characterize the immunocompetent shifts from the stage of initial sensibilization to the stage of autoimmune r_action. Changes in low-molecular-weight components characterize the catabolic shifts from the stage of initial disturbances in glycolipoprotein mediators to the stage of pronounced disaggregation of biosubstrates in biological fluids. Simultaneous changes in both high- and low-molecular-weight subfractions of biological fluids will characterize more complex states. Oropharyngeal washout fluids from 94 children with scoliosis of different severity were analyzed by LCS. The data presented on Fig. 1 attest to a drastic increase in the content of low-molecular weight components during stages I and II of scoliosis (which corresponds to intoxication-like shifts according to the semiotic classifier). During the third stage the content of these components slightly decreased, while the content of high-molecular-weight components increased almost 3-fold. These changes can be classified as autoimmune-like shifts. LCS-spectra of washout fluids from children with stage IV scoliosos little differed from those in patients with stage III scoliosis: autoimmune shifts predominated and intoxication-like changes were still highly pronounced. 4. Discussion The observed metabolic changes can be determined by various mechanisms. Apart from above mentioned activation of metalloproteases induced, in particular by physical work [4], biological fluids of patients with scoliosis contain high concentrations of glucoproteins and

G.P. Dmitrievu et al. / New Approach to Objective Diagnostics

Pic. 1. Patterns of distribution of light-scattering particles in oropharyngeal washout fluids from children with scoliosis of different severity.

protein CD-RAP [4]. Experiments on mice showed that expression of kyphoscoliosis gene is associated with overproduction of a specific protein [5]. Hence, early stages of scoliosis are characterized by accumulation of low-molecular-weight protein components. The appearance of these components in biological fluids is a result of destructive catabolic processes. Drastic accumulation of autoimmune components in children with severe scoliosis is probably a response to intervertebral disk degradation products and novel proteins. The revealed relationships between integral metabolic parameters will help to evaluate the dynamics of the disease and to choose pathogenetically substantiated correction of biochemical processes in scoliosis. 5. Conclusions Our findings suggest the possibility of using the proposed approach in elaboration of objective expert systems for prediction of the severity of pathological complications of spine deformities and for improving the selectivity of therapeutic measures. References 1. 2. 3.

4. 5.

R.D. Blank et al., A genomic approach to scoliosis pathogenesis, Lupus 8(5) (1999) 356-60. J.K. Crean et al., Matrix metalloproteinases in the human intervertebral disc: role in disc degeneration and scoliosis, Spine 22(24) (1997) 2877-84. J.D. Rang et al. Toward a biochemical understanding of human intervertebral disc degeneration and herniation. Contributions of nitric oxide, interleukins, prostaglandin E2, and matrix metalloproteinases, Spine 22(10) (1997) 1065-73. N. Natsume et al., Analysis of cartilage-derived retinoic acid-sensitive protein in cerebrospinal fluid From patients With spinal diseases, Spine 26(2) (2001) 157-60. G. Blanco et al., The kyphoscoliosis (Icy) mouse is deficient in hypertrophic responses and is caused by a mutation in a novel muscle-specific protein, Hum. Mol. Genet. 10(1) (2001) 9-16

77).H CnvasiKit , Research into Spinal Deformities, 4

Spinal Mobility and EMG Activity in Idiopathic Scoliosis Through Dynamic Lateral Bending Tests OC Ciolofan1'2, C-E Aubin1'2, PA Mathieu u , M Beausejour '. V Feipel13. H Labelle ' 1-Sainte-Justine Hospital, 3175 Cote Ste-Catherine Rd, Montreal, H3T1C5, Canada 2- Biomedical Engineering Institute, Univ. Montreal / Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-ville, Montreal, H3C3A7, Canada 3-Lab. for Functional Anatomy, University of Brussels (CP 619), 808, route de Lennik, B-1070 Brussels, Belgium Abstract. Lateral bending test is a common evaluation of AIS patients prior to their surgical correction. Traditionally this evaluation is made by the assessment of the curve's flexibility from side-bending radiographs. As a complement to this static test, dynamic bending was experimented while simultaneously quantifying muscular and kinematic behavior of the spine. The biggest contribution to total EMG output was 36% from lumbar muscles in healthy and 35% from abdominal muscles in scoliotic subjects. Continuous measuring of kinematics and muscle activation patterns throughout lateral bending could be an evaluation tool for distinguishing pathological from normal behavior.

1. Introduction Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine whose hallmark is the lateral curve in the frontal plane. It is accompanied by a deformity of the rib cage (rib hump), pelvis and shoulders. Muscular alterations that could result from the scoliosis condition or may be at its origin are also present [1]. Severe cases are commonly treated by instrumentation and spinal fusion. Levels to be included in the arthrodesis are based on the "flexibility" of the spine evaluated from static side bending radiographs [2, 3,4]. From the observations of different authors regarding fiber distribution and functions of trunk muscles in idiopathic scoliosis, muscular activity analysis in the preoperative assessment of scoliotic patients could be of great interest. For instance, it seems that the erector spinae muscles present a greater activity on the convex side of the curve [5, 6] but few studies have recorded trunk muscles activity concurrently to spinal kinematics in AIS patients [7, 8]. The objective of this study was to simultaneously quantify spinal mobility and EMG activity in AIS patients and control subjects throughout dynamic lateral bending test. 2. Materials and Methods Subjects. Eight AIS patients with single right thoracic curve and indication of surgical correction took part in the experiment as well as seven healthy controls with no history of back problems. No significant differences were detected between groups as in regard to age, height and weight. The Sainte-Justine Hospital's Ethical Committee approved the protocol and each subject and one of his parents signed a consent form.

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13 1

Data collection and processing. Kinematic data were obtained by tracking the 3D positions of 11 to 13 small infrared light-emitting diodes (LEDs) with 3 cameras (Optotrack 3020, Northern Digital Inc., Waterloo, Canada). The LEDs were affixed to the skin surface overlying anatomical landmarks as shown in figure 1 (circles). Sampling rate for each marker was 50 Hz and their positions determined with an accuracy of 0.1 mm. By projecting the line joining markers at Tl and L5 in the frontal plane, inclination of the spine in relation to vertical axis was obtained. The spine curve angle (SCA) was defined as the angle between the two scoliotic segments: one joining the lower end to the apex and the other one joining the apex to the upper end vertebrae corresponding to the Ferguson angle [9].

Figure 1: Placement of LEDs (j and surface EMG electrodes C ) in a healthy subject (A) and a scoliotic -ubject (B); UEV=upper end vertebra, AV=apical vertebra, LEV=lower end vertebra

For surface EMG recording, 23 pairs of Nutab™ electrodes in healthy subjects and 19 pairs in AIS patients were used. Following appropriate skin preparation to reduce skin impedance, the 10 mm diameter electrodes were placed on the skin at levels shown in figure 1 (pairs of rectangles). Output of Grass™ amplifiers model 15 (gain: 1000, bandpass filter 31000 Hz) was digitized online with a National Instrument™1 data acquisition card (A/D: 2000 Hz) controlled by a Labview™ user interface. Before processing, all digitized EMG signals were filtered to eliminate interference from 60 Hz, electrocardiographic activity, motion artifacts and baseline drifts when present. Then, root mean square (RMS) values were calculated for each signal and areas under the RMS curves were used to assess the muscular output. Since similar values were obtained from electrodes in a same region, they were grouped leading to 4 groups: left thoracic, right thoracic, left lumbar and right lumbar. Abdominal electrodes formed 2 more groups: left abdominal and right abdominal. Denoting by Jj the EMG activity of a certain group, where J=[thoracic (T), lumbar (L), abdominal (A)] and i=[right (R), left (L)], an asymmetry ratio of muscular activity is defined as: ARj=(JaJL)/(JR+JL)- Differences in muscular activities between left and right as well as the two groups of subjects were statistically analyzed with the nonparametric Mann-Whitney U test [10] (a p value of less than 0.05 was considered significant).

3. Results An example of the EMG signals, velocity and inclination obtained during a right lateral bending from one control and one patient is illustrated in figure 2. The maximal velocity is smaller and appears earlier in the bending for patients than for controls. Most EMG activity is found in the right thoracic (convex side) and the left lumbar muscles in the patient and in the left lumbar muscles in the control subject.

O.C. Ciolofan ct al. /Spinal Mohititv anil EMC Activity in Idioputhu Set

Figure 2 : EMG signals, velocity and inclination throughout a right lateral bending motion for a patient with right thoracic AIS (A) and a control subject (B). Scale is the same for all EMG signals.

In healthy subjects the lumbar muscles contributed 36% of the total EMG output, whereas thoracic muscles contributed 34% and abdominal muscles 30%. The relative contributions in patients were 33%, 32% and 35% for lumbar, thoracic and abdominal muscles respectively. The muscle activity asymmetry between the right and left sides of the body is shown in table 1, where a negative ratio means a predominance of left side activity and a positive ratio, right side activity predominance. For the healthy subjects the antagonists (left side muscles in right bending and right side muscles in left bending) were more active than the agonists. The same right/left muscular asymmetry was maintained for both right and left bending tasks in patients. In average, the right thoracic, left lumbar and right abdominal muscles of scoliotic patients exhibited greater EMG output than their counterpart muscles. However, there was no statistically significant difference between the healthy and scoliotic subjects regarding these ratios (p>0.05). Table 1: Median, min and max values of muscle activity asymmetry ratios for thoracic (ART), lumbar (AR L ) and abdominal (AR A ) regions during right and left bendings for healthy (H) and scoliotic (S) subjects Right Bendtttj AR,, ART AR* H S H S H S H S Median -0.04 0.01 -0.10 -0.02 -003 -0.01 0.06 0.02 Min -0.29 -0.12 -0.20 4.19 -022 -021 -0.14 -0.12 Max 0.09 0.19 0.05 0.17 0.12 022 020 0.40

ART

Left Bending AR,. AR* H S H S 0.03 -0.03 0.00 0.15 -0.16 -035 -026 -028 022 0.17 0.07 023

Figure 3 A and B shows an example of 2 patients with different behaviour. The curve reducibility (difference in SCA between standing and bending positions) in A is bigger than in B. Also, in A the muscular activation at apical level is bigger on the concave while in B it is bigger on the convex side. For both patients the maximal muscular activities appear at a moment during the opening of the curve. The correlation between thoracic muscle activity asymmetry ratio and curve's reducibility is shown in figure 3 C. Although the number of patients is low (8), a trend of increased curve reducibility for a predominance of concave side muscles is observed (R2=0.41).

O.C. Ciolofan et at. /Spinal Mobility and EMC Activity in Idiopathic Scoliosis

R2 = 0.41

time(s)

ART

Figure 3 : Time courses of scoliotic curve angle (SCA) and RMS signals of right and left iliocostalis at apical level during right bending of 2 patients (A and B). Correlation between scoliotic curve reducibility and thoracic muscle activation asymmetry ratio (C)

4. Discussion and Conclusions The results confirm the predominance of convex thoracic muscle activity shown by previous studies [5,6,7,8]. Muscular recruitment and kinematic patterns were different between AIS and normal subjects. This suggests that kinematic and EMG data could help to better understand the stiffness and mobility changes that take place in scoliotic spines. It is necessary to provide data on a larger patient group and to evaluate the relationships between these results and radiographic parameters presently used in surgical planning and postoperative outcome in order to demonstrate the clinical benefices of this non-invasive test. It could be suspected that in patients with the same degree of severity of scoliosis and the same reducibility, the correction level obtained could be attributed in part to trunk muscle asymmetry. In conclusion, the results of this study emphasise the fact that knowledge of the muscular activation patterns, beside the spinal mobility assessment in AIS patients might improve the surgical planning. 5. Acknowledgements. The authors wish to thank: Mrs Julie Joncas, research nurse and the patients and healthy subjects who participated in this study. References 1. 2.

3. 4. 5. 6. 7.

Reuber, M., Schultz, A., McNeill, T., and Spencer, D. (1983): Trunk muscle myoelectric activities in idiopathic scoliosis, Spine, 8, pp. 447-456 Vaughan, J. J., Winter, R. B., and Lonstein, J. E. (1996): Comparison of the use of supine bending and traction radiographs in the selection of the fusion area in adolescent idiopathic scoliosis, Spine, 21, pp. 2469-2473 Polly, D.W., Sturm, P.P. (1998): Traction vs supine side bending. Which technique best determines curve flexibility?, Spine, 23, pp. 804-808 Klepps, S.J., Lenke, L.G., Bridwell, K.H., Bassett, G.S., Whorton, J. (2001): Prospective comparison of flexibility radiographs in adolescent idiopathic scoliosis, Spine, 26, pp. E74-E79 Avikainen, V. J., Rezasoltani, A., and Kauhanen, H. A. (1999): Asymmetry of paraspinal EMG-time characteristics in idiopathic scoliosis, /. Spinal Disord., 12, pp. 61-67 Zetterberg, C., Aniansson, A., and Grimby, G. (1983): Morphology of the paravertebral muscles in adolescent idiopathic scoliosis, Spine, 8, pp. 457-462 Gram, M.C., and Hasan, Z. (1999): The spinal curve in standing and sitting postures in children with idiopathic scoliosis, Spine, 24, pp. 169-177

O.C. Ciolofan cJ al. /Spinal Mohiliiv anil EMG Activit\ in Idiopaihii Scolioxis

8.

9. 10.

Hopf, C, Scheidecker, M., Steffan, K., Bodem, F., and Eysel, P. (1998): Gait analysis in idiopathic scoliosis before and after surgery: a comparison of the pre- and postoperative muscle activation pattern, Eur. Spine J., 7, pp. 6-11 Ferguson, A.B. (1945): Roentgen diagnosis of the extremities and spine, New York, Hoeber Bland, M. (1995): An introduction to medical statistics. Oxford university press, pp. 206-212

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Three Dimensional Analysis of Chest Wall Motion during Breathing in Healthy Individuals and Patients with Seoliosis using an Ultrasonography-based System Toshiaki Kotani,* Shohei Minami, * Kazuhisa Takahashi,* Keijiro Isobe,* Yoshinori Nakata,* Masashi Takaso,* Masatoshi Inoue,* Shinsuke Nishikawa,* Tetsuro Maruta,* Tamotsu Tamaki, f Hideshige Moriya* *Department of Orthopedic Surgery, Graduate School of Medicine, Chiba Universily, Chiba, Japan t Nippon Institute of Technology, Faculty of Engineering, Saitama, Japan

Abstract. The mechanical inefficiency during respiration in scoliosis remains unclear. Aim: To study the three-dimensional motion of the chest wall during deep breathing in healthy and scoliotic individuals. Materials & Methods: Threedimensional chest wall motion during breathing was studied in 17 scoliotic patients (right thoracic curvature) and 9 healthy individuals. Measurements were performed using a Zebris CMS 70P system (Zebris Medizintechnik GmbH, Isny, Germany) which analyzes the time delay of ultrasound pulses emitted from markers placed on the chest wall. Nine markers were attached on the upper, the middle and the lower chest wall. Subjects were seated on a chair and asked to breathe deeply and slowly with no elevation of the shoulders for one minute. Results: The amplitudes were symmetric between the two sides in healthy individuals while scoliotic patients exhibited asymmetric chest wall motion. The amplitudes of the right convex side of the chest wall exhibited less motion than those of the left concave side, especially on the lower chest wall. Conclusion: Chest wall motion was asymmetric in the scoliotic patients with diminished motion of the right lower chest wall. This locally diminished ventilation may cause ventilation-perfusion inequality and result in hypoxemia.

1. Introduction The deleterious effects of thoracic spinal deformity on respiratory mechanics have been reported by several investigators [1]. Although the overall lung function in scoliosis has been studied through the use of spirometry, little work has been done on regional function, furthermore the findings are not necessarily the same between the authors. Thus, the characterization of respiratory insufficiency in scoliosis remains unclear. Few reported studies have been performed using three-dimensional chest cage kinematics during breathing for healthy or scoliotic individuals [2]. The effects of the surgery on the respiratory mechanics is also unknown. The purpose of this study is to investigate the three-dimensional motion of the chest wall during deep breathing in healthy subjects and scoliotic patients, using an ultrasonographybased system for the evaluation of respiration mechanics.

T. Kotuni a at. / Three Dimensional Amil\\is' of Chest Wall Motion

2. Patients and Methods Seventeen patients (16 females, 1 male; age, 11-20 years, with an average of 15.6 years) with scoliosis (16 idiopathic, 1 syringomyelic) and 9 healthy individuals (8 females, 1 male; age, 13-20 years with an average of 17.4 years) were enrolled in this study. All the scoliotic patients had a right thoracic curve with a mean angle of 53.7+12.90 (range, 40—850) according to Cobb's method. The vertebra at the apex of the curve was located between T7 and T10. On the basis of historical data and physical examination, co-existing lung disease, especially asthma, was excluded. Surgery performed was posterior spinal fusion with Chiba Spinal System in 6 patients. Chest wall motions were recorded using the motion analysis system Zebris CMS 70P (Zebris Medizinteelmik GmbH, Isny, Germany), that analyzes the time delay of ultrasound pulses emitted from markers placed on the chest wall. The measuring procedure is based on the determination of the spatial coordinates of miniature ultrasound transmitters whose position relative to a fixed system of three microphones is derived from the time delay between the ultrasound pulses, using triangulation. The small and lightweight markers were attached to the subject. To record the chest wall motion, markers were placed on the right and left sides of the upper chest (at the level of the second rib), middle chest (sixth rib), and lower chest (tenth rib). The right and left markers were placed 8cm from the center marker on the second rib level, and on the lateral corners of the chest cage (points 7 and 9) of the lower chest. Markers 4 and 6 were added bilaterally at the midpoint between points 1 and 7, and points 3 and 9, respectively (Figure 1). This distribution was reported by Leong et al [21. As shown in Figure 2, the measuring sensor was positioned 80cm in front of a subject. The subject was seated on a chair and asked to breathe deeply and slowly with no elevation of the shoulders for one minute. In order to stabilize their sitting posture, vertical bars located in front of the subjects were held by each hand. The three-dimensional position of the chest wall was calculated by the system's dedicated software and graphically displayed in real time. The results were sent to a personal computer and analyzed off-line, using cursors to measure the displacements for each respiration. These values were recorded manually and the average amplitude was calculated for each direction.

Measuring sensor

Figure 1. Placement ofmarkers on the chest wall

Figure 2. Experimental setup

3.Results Figure 3 presents three-dimensional movement in absolute values. This indicates that the amplitudes were symmetric between the two sides in healthy individuals, while in

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scoliotic patients the amplitudes of the right convex side of the chest wall exhibited less motion than those of the left concave side, especially on the lower chest wall. The differences in motion between the right and left sides at every level of the chest wall in scoliotic patients were statistically significant (P<0.05). No significant difference was found in the average amplitude for each motion between controls and scoliotic patients. The chest wall motions varied among study participants, suggesting different breathing habits. To reveal the motion patterns, the absolute values were normalized. The percentage of each displacement relative to the right middle displacement was calculated. The reason we chose the right middle wall is because these values were almost the same between the two groups. To normalize, each absolute value was divided by the amplitude of the right middle chest wall. The data were analyzed separately for each of the three directions. In healthy individuals, the upper chest wall in the anteroposterior direction showed the least displacement, while the right lower chest wall showed the least displacement in scoliotic patients (Figure 4). The chest wall motion in the lateral direction showed a progressive increase from the upper to the lower in healthy individuals. The left wall motion CmrrA

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Figure.3 Three dimensional movement Control

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Figure.4 Percentage of amplitude in the anteroposterior direction (fright middle: 100%) Control Upper

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Figure.5 Percentage of amplitude in the lateral direction (fright middle: 100%)

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T. KoJuni et al. / Three Dimensional Analvxi.x of Chest Wall Motion

in scoliotic patients showed the same tendency, though the movement of the right chest wall was significantly reduced (Figure 5). The amplitudes for the patients who underwent a posterior spinal fusion were presented in Figure 6. Before surgery, all the patients showed asymmetric motion between the two sides. One month after surgery, the amplitudes of motion were reduced and still asymmetric. The motion patterns were similar three months after surgery, but the amplitudes had increased, although not to the level of the pre-operation period. 4. Discussion Scoliosis can impede the function of chest wall motion. The results of previous studies have suggested that mechanical factors, such as chest cage movements, were related to the impairment of pulmonary function [4,5]. Although these movements are recognizable clinically, they have proved to be very difficult to measure and to describe because of the limited methods available to measure chest wall movement and the difficulties in expressing these measurements in a way that can be easily understood. Leong et al [2] used a four-infrared-camera system to analyze chest wall motion, but the system requires a larger space and seems to be unsuitable for routine use. The ultrasonography-based system is easy to use without any calibration, it works in real time, and are prepared for further feedback and training tasks. Additionally, it works even in small rooms. The method is noninvasive and nonionizing, and is thus suitable for routine clinical analysis. The present findings showed a difference in the respiratory chest wall motion between the healthy individuals and scoliotic patients. The motion of the chest wall in controls was symmetric, and the motion of the lower chest wall was greater than that of the upper chest wall. In comparison, the amplitude of motion of the right chest wall in scoliotic patients was reduced, and the least displacement was in the right lower chest. Not all regions of the lung have the same ventilation and perfusion. In healthy subjects, ventilation per unit volume is greatest near the bottom of the lung and becomes progressively smaller toward the top [6]. In the upright human lung, blood flow decreases almost linearly from bottom to top, reaching very low values at the apex. This pattern is desirable for normal respiration. Post op. 1M

Preop

Upper

Lower

Upper

Middle

Post op. 3M

Lower

Figure.6 Three dimensional movement

Upper

Middle

Lower

[_j Right {^Left

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139

In scoliotic patients, the diminished right lower chest wall motion may decrease the ventilation in the right lower lung. However there is still much perfusion in this region. Bake et al [71 reported that scoliotic patients showed a relatively normal distribution of pulmonary blood flow when the vertebra at the apex of the curve was located between T6 and L4. This diminished ventilation can cause ventilation-perfusion inequality. If the same amounts of gas are being transferred, the lung with ventilation-perfusion inequality cannot maintain as high an arterial P02 as a homogeneous lung [7]. This locally diminished ventilation can be responsible for hypoxemia. Thus, reduced regional motion of the chest wall may be a contributing factor to the decreased respiratory function that is seen before surgery. Results of the present study suggest that the asymmetric motion of the chest wall was unchanged in the scoliotic patient at one and three months after surgery, although the amplitudes had increased by the three month point. Even though gross distortion of the thorax had been corrected by surgery, we couldn't find an improvement of the respiratory pattern. This may be due to the contracture of the thorax. In addition, we need further long-term follow-up. Further studies will be needed to determine what long-term changes take place. In conclusion, the chest wall motion was asymmetric in the scoliotic patients, with diminished motion of the right lower chest wall. This locally diminished ventilation may cause ventilation-perfusion inequality and result in hypoxemia. References 1. 2. 3. 4. 5.

6. 7.

K. Pehrsson, B. Bake, S Larsson, et al., Lung function in adult idiopathic scoliosis: a 20 year follow up, Thorax 46( 1991 )474-478 J. C. Leong, W. W. Lu, K. D. Luk, E. M. Karlberg, Kinematics of the chest cage and spine during breathing in healthy individuals and in patients with adolescent idiopathic scoliosis, SPINE 24(1999) 1310-1315 W. A. Littler, I. K. Brown, R Roat, Regional lung function in scoliosis, Thorax 27 (1972) 420-428 —130 D. M. Cooper, J. V. Rojas, R. B. Mellins et al., Respiratory mechanics in adolescents with idiopathic scoliosis, Am Rev Respir Dis 130 (1984)16-22 S. S. Upadhyay, E. K. W. Ho, W. M. S. Gunawardene et al., Changes in residual volume relative to vital capacity and total lung capacity after arthrodesis of the spine in patients who have adolescent idiopathic scoliosis, J Bone Joint Surg [Am] 75 (1993) 46-52J. B. West, Respiratory Physiology -The essentials, 5th ed., Williams & Wilkins, Baltimore (1995)11-20 B. Bake, J. Bjure, J. Kasalichy et al., Regional pulmonary ventilation and perfusion distribution in patients with untreated idiopathic scoliosis, Thorax 27 (1972) 703-712 J. B. West, Respiratory Physiology - The essentials, 5th ed., Williams & Wilkins, Baltimore (1995) 5169

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Th.K.(jri\(i.
Relation between the Pelvis and the Sagittal Profile in Adolescent Idiopathic Scoliosis: the Influence of Curve Type ManonCharlebois1, Jean-Marc Mac-Thiong1>2, Marie-Pierre Huot2, Jacques A. de Guise3, Wafa Skalli4, Hubert Labelle1'2 1 - Faculty of Medicine, Universite de Montreal, PO Box 6128, Station Centre-ville, Montreal (Quebec), Canada H3C3J7 2 - Research Center, Sainte- Justine Mother-Child University Hospital, 3175 Cote-SainteCatherine, Montreal (Quebec), Canada H3T1C5 3 - Department of Automated Production Engineering, Ecole de Technologic Superieure, 1100 Notre-Dame West.Montreal (Quebec), Canada H3C1K3 4 - Laboratoire de Biomecanique, Ecole Nationale Superieure d'Arts el Metiers, 151 Boulevard del'Hopital, 75013 Paris, France Abstract. Previous studies have shown a correlation between pelvic parameters and the lumbar lordosis in normal subjects and in scoliotic adults. This study investigates the relationship between pelvic and spinal geometries in the sagittal plane for adolescent idiopathic scoliosis (AIS) patients having various curve types. The study group was composed of 129 AIS patients classified according to their curve type: King I, King II, King III or lumbar curve. The SpineView software (Surgiview, France) was used to compute five parameters on sagittal x-rays: thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT) and pelvic incidence (PI). The TK was significantly lower for King I, II and III curves as compared to the lumbar curves. The LL tended to be higher for patients having a major lumbar scoliotic (King I and lumbar) curve, although not significantly. No significant change between the groups was observed for the SS, PT and PI. The PI was significantly correlated to the LL, SS and PT for all groups. The SS was strongly related to the LL in all cases. However, no relationship was found between the TK and the LL in any group. This study showed that the TK mostly depends on the thoracic scoliotic curve and therefore on the shape and orientation of the vertebrae, which explains that many King I, II and III patients are hypokyphotic. Conversely, the LL is mainly influenced by the pelvic configuration. Since the pelvic parameters are similar for all groups, these parameters are not likely to be important in the development of a specific type of scoliotic curve.

1. Introduction The standing posture involves a close interdependence between the spine and pelvis. Duval-Beaupere et al. [1] have raised the important effect of the pelvic geometry in the maintenance of an adequate sagittal balance. They introduced a new anatomical parameter, the pelvic incidence, which is specific to each individual and unaffected by the 3-D orientation of the pelvis. This parameter is related to the lumbar lordosis in normal subjects [1-3]. As shown by Legaye et al. [3], there is also a significant relationship between the pelvic incidence and the lumbar lordosis in scoliotic adults. Furthermore, although the pelvic incidence was similar for normal subjects and scoliotic patients, Legaye et al. [3] suggested that the Cobb angle may have a negative effect on the pelvic incidence and consequently on the sagittal balance. The purpose of this work was to investigate the relationship between the pelvic and spinal geometries in the sagittal plane for patients having adolescent idiopathic scoliosis (AIS). The influence of the scoliotic curve type was also evaluated.

M. Charlebois et al. / Relation between the Pelvis and the Sagittal Profile

14 1

2. Materials and Methods The x-ray charts of 129 patients diagnosed with AIS at the Sainte-Justine Hospital were reviewed. The inclusion criteria were: 1) Cobb angle of > 10°, 2) age between 10 and 18 years, 3) no neurological deficits and 4) no previous spine surgery. The characteristics of the patients according to their curve type are described in Table I . Two spinal and three pelvic parameters were measured on the standing sagittal xrays using the Spineview® software (Surgiview, France) (Figure 1-A). The thoracic kyphosis (TK) between T4 and T12 and the lumbar lordosis (LL) between LI and L5 were computed using the Cobb technique. The pelvic parameters are shown in 1-B. The pelvic incidence (PI) is the angle between the perpendicular of the upper sacral plate and the line joining the middle of the upper plate and the bicoxofemoral axis. The sacral slope (SS) is the angle between the upper sacral plate and the horizontal. This parameter depends on the pelvic morphology as well as the 3-D orientation of the pelvis. The pelvic tilt (PT) represents the angle between the vertical and the line joining the midpoint of the sacral plate and the bicoxofemoral axis. It is positive when the bicoxofemoral axis lies in front of the midpoint of the sacral plate. Data were analyzed using the Statistica® software (StatSoft, USA). The influence of curve type and the correlation between all parameters were assessed using ANOVA and Pearson's coefficients, respectively. The level of significance was set at 0.01. Table 1: Patient characteristics tor the adolescent idiopathic scoliosis group

N Age Cobb

King I

King II

King III

Lumbar

32 13.5±2.1 45.3±16.7°

34 13.711.9 51.2113.7°

42 13.411.8 43.0+13.0°

21 13.212.3 37.2111.9°

B

B) Pelvic parameters

M. Cliarlehoix el
142

3. Results The mean values and standard deviations for all groups as well as the results from the ANOVA are shown in Table III. The TK was significantly lower for King I, II and HI curves as compared to lumbar curves. The lumbar lordosis tended to be higher for patients with a major lumbar scoliotic (King I and lumbar) curve, although not significantly. The pelvic parameters were similar between all groups. The results from the linear regression analysis between the pelvic and spinal parameters for all groups are shown in Table 3. The TK was not related to any parameter, except for the SS and the PI in the King III group. The TK was unrelated to the LL in all cases. The LL was correlated to the PI and the SS for all groups. The correlation coefficient was stronger with SS than with PI for all groups, except for patients with a King II curve. There was also a significant relationship between the LL and the PT for King II curves. The PI was related to the PT and the SS in all groups but no correlation was found between the SS and the PT. The PI was not related to the Cobb angle in any group.

Table 2: Spinal and pelvic parameters in the suL'iual plane lor all groups (mean ± standard d e \ i a t i o m

Parameter Group

Thoracic kyphosis

Lumbar lordosis

Pelvic incidence

Sacral Slope

Pelvic Tilt

King I (n=32) King II (n=34) King III (n=42) Lumbar (n=21)

20.4±8.4° 22.0111.1° 20.3±12.0° 30.6±9.9°

41.9±11.3° 40.7±8.4° 40.8±10.8° 45.4±13.0°

57.0±15.7° 59.1±12.4° 56.3±13.7° 58.6114.3°

48.1111.3° 48.217.4° 47.919.2° 48.2110.3°

8.9+9.5° 10.918.3° 8.417.9° 10.319.1°

ANOVA (p value)

<0.01*

>0.01

>0.01

>0.01

>0.01

* Significant change (p < 0.01) Table 3: Correlation coefficients < r ) between the parameters tor all groups Group Parameters

King I (n=32)

King II (n=34)

King IE (n=42)

Lumbar (n=21)

Kyphosis-Lordosis

0.21 -0.17 -0.08 -0.19 0.64* 0.80* 0.11 0.80* 0.70* 0.14

0.14 -0.14 -0.24 -0.002 0.68* 0.57* 0.52* 0.76* 0.82* 0.24

-0.07 -0.44* -0.43* -0.26 0.55* 0.65* 0.20 0.84* 0.77* 0.29

0.27 -0.11 -0.08 -0.08 0.60* 0.77* 0.08 0.78* 0.70* 0.09

Kyphosis-Incidence Kyphosis-Sacral slope Kyphosis-Pelvic tilt Lordosis-Incidence Lordosis-Sacral slope Lordosis-Pelvic tilt Incidence-Sacral slope Incidence-Pelvic tilt Sacral slope-Pelvic tilt

* Significant change (p < 0.01)

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4. Discussion This study showed that the thoracic kyphosis in AIS was dependent mostly on the thoracic scoliotic curve and therefore, on the shape and orientation of the thoracic vertebrae. Conversely, the lumbar lordosis was mainly influenced by the pelvic configuration. The presence of a major lumbar curve had only a weak effect, as it tended to slightly increase the lumbar lordosis. Because they were influenced by different parameters, the thoracic kyphosis and the lumbar lordosis were not correlated in this study although this is the case in many studies involving normal subjects [2-3]. The results also showed that the pelvic parameters were similar for all curve types. These parameters are therefore not likely to be important in the development of a specific type of scoliotic curve. The pelvic incidence of all AIS groups was higher than the mean pelvic incidence found in another study [4] done on 27 normal adolescents aged 13 years old in average. Descamps et al. [4] reported a pelvic incidence of 46.8 ± 11.2° for these subjects. Considering this discrepancy, it is possible that the pelvic incidence influences the pathogenesis of scoliosis. However, a normal database assessed using the Spine View® software is required to verify this assumption. A prospective study with AIS patients would also be important in order to evaluate the influence of the pelvis on the progression of AIS. References 1. 2. 3. 4.

G Duval-Beaupere et al., A barycentremetric Study of the sagittal shape of spine and pelvis: the conditions required for an economic standing position, Ann Biomed Eng 20 (1992) 451-462. G Vaz et al., Sagittal morphology and equilibrium of pelvis and spine, Bur Spine 111 (2002) 80-87. J Legaye et al., Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves, Eur Spine J 7 (1998) 99-103. H Descamps et al., Modifications des angles pelviens, dont 1'incidence, au cours de la croissance humaine, Biom Hum et Anthropol 17 (1999) 59-63.

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Th.B. (JrivuM&l., Research into Spinal Deformities 4 IOS Preys. 2<)»2

Study of Patient Positioning on a Dynamic Frame for Scoliosis Surgery K. Dukeu, J. Dansereau1'2, H. Labelle1, A. Roller1, J. Joncas1, C-E. Aubin1-2 1-Sainte-Justine Hospital, 3175 Cote Ste-Catherine Rd, Montreal, H3TJC5, Canada 2- Biomedical Engineering Institute, Ecole Polytechnique de Montreal, P. O. Box 6079, Station Centre-ville, Montreal, H3C 3A 7, Canada Abstract The goal of this clinical trial was to measure patient geometry on a dynamic positioning frame in various prone positions. Fourteen subjects (2 males and 12 females) were recruited from the scoliosis clinic at Ste-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle, averaged 50° (32°-64°). The mean age was 14.1 years (11-17). A Polaris system (Northern Digital inc, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. Acquisitions were made while the unanaesthetized patient was in five different prone positions: I similar to the standard positioning on a Relton-Hall frame; II addition of a force applied to the ribcage at the apex of the curve; II! application of a force at the apex of die curve in the lumbar region; IV, the shoulder pads were elevated to increase the patient's kyphosis; V adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. Position III had a significantly negative change in the rib hump. During position IV, there was a measurable increase in kyphosis. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal patient position has not yet been found and future studies are directed at determining this.

1. Introduction The position of the patient during scoliosis surgery is a critical step in the surgical procedure. The fathers of the modern prone spinal frame are Relton and Hall who emphasies that the abdomen must remain free and pendulous during the surgery to minimize blood loss [1]. Callahan et al. described various positioning techniques for spinal surgery [2]. They identified the three most important factors attributing to optimal position as stability of the spine, exposure required and physiological limitations. For posterior thoracic and lumbar surgery they recommend the Relton-Hall frame since it allows the abdomen to hang freely alleviating pressure on the vena cava and there by reducing blood loss. Tables similar to the Relton-Hall frame are sometimes referred to as four post, chest roll, and the Jackson table. The loss of lordosis, due in part to improper positioning of the patient, is considered a complication of scoliosis instrumentation. Many studies have analyzed the effect of patient position, specifically hip angle, on lumbar lordosis [3,4,5]. In general, positions

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145

where the hips are flexes less then 30 degrees maintains a lordosis similar to that found in the standing position. The effect of patient positioning on the spinal curves in the frontal plane is not clearly understood. A study by Delorme et al. found that a significant and important correction to the thoracic and lumbar Cobb angle of 37% is due to prone positioning, surgical exposure and anesthesia [6]. In a recent study by Mac-Thiong, where the feasibility of tracking of the trunk during scoliotic surgery was analyzed, they found that trunk geometry was influenced by the positioning of each subject on the operating table more than the magnitude of the spinal deformity [7]. The previously mentioned results provide some of the motivation for the current study. Recently, a new positioning system has been designed at the Sainte Justine Hospital. Before it can be used in the operating room its effect on patient trunk geometry in the clinic will be studied. 2. Objective The purpose of this study was to measure patient geometry on a positioning frame in various prone positions. 3. Materials and Methods Fourteen subjects (two males and twelve females) were recruited from the scoliosis clinic at Sainte-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle on their x-rays, averaged 50° (32° to 64°). The mean age was 14.1 years (11 to 17). A Polaris system (Northern Digital inc, Waterloo, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. The reflective markers were put on the patient as shown in Figure 1. The markers were on C7, left shoulder, right shoulder, prominence of the rib hump on the right and left sides, prominence of the lordotic hump on the right and left sides, the right and left iliac dimples and on SI. The marker on SI consists of a triangle with three markers (A, B, C as shown in Figure 1). This was used as a reference frame and a coordinate system similar to that defined by the SRS was used. The origin is at the base of the triangle on point C. The y axis directed towards the left of the patient is parallel to the line formed by points A and B. The z axis points cranially and is defined as the line between points C and the midpoint between A and B. The x axis, pointing anteriorly is orthogonal to the y and z axis. From the ten measured points various indices were calculated including: Spine length, which is equal to the distance between points C7 and SI. From these two points the decompensation angle and distance was also calculated. From the markers on the shoulders the angle of the shoulders in the yz and xy plane was calculated with respect to the y axis. Similarly the rib hump and lumbar hump were calculated in both planes. The kyphosis could not be measured directly but was quantified by the height difference of points 4 and 5 measured from the line joining points C7 and SI as schematically represented in Figure 2.

146

K. Duke a f Patient Positioning on a Dvnamit Frame

Figure 1: Measured anatomical landmarks

Acquisitions were made while the unanaesthetized patient was in five different prone positions. Patients were placed on a positioning frame similar to the Relton-Hall design except that the cushions can be translated in the x, y, and z, directions. Position I was similar to the standard position on the Relton Hall frame. The patient was placed on the cushions so that their iliac crests were just at the superior boarder of the hip cushion. To support the upper body the shoulder cushions were placed with the superior border just under the patients' arm-pit. Position II was similar to Position I except for the addition of a force applied to the ribcage at the apex of the curve. This force was applied by hand and was consistently applied by the same person (JJ). For Position III the corrective force was applied at the apex of the curve in the lumbar region. For position IV, the shoulder pads were elevated in an attempt to increase the patients' kyphosis. Position V involved the adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions.

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147

Figure 2: Measured indices

4. Results The statistically significant results are summarized in Table 1. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. The decompensation of the patient was also over corrected. Position III had a significantly negative change in the rib hump. The decompensation of the patient was also negatively affected. There was no significantly positive influence on the lordotic hump and the application of this force alone is not recommended. During position IV, there was a measurable increase in kyphosis height as measured from the distance from points 4 and 5 to the line connecting points 1 and 10. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. There were no adverse negative corrections and none of the parameters were over corrected. This combination of adjustment of the height of the cushions and the application of both a lumbar and thoracic force produces the best results out of the four positions. This is considering the average for the 14 patients and it should be noted that for each patient the optimal forces would differ.

US

Table 1: Statistically significant results from the various trials. t Denotes significant over correction. § Denotes a significantly negative result Shoulders Top view Shoulders AP view Decompensation Angle Decompenstaion Distance Balance Angle Spine Length Rib Hump Top view Rib Hump AP view
PI:PII NoDiff -2.9 to 3.3f 1.1 to-1.9t 0.9to-1.4f NoDiff NoDiff 5.9 to 3.3 1.1 to4.4§ NoDiff NoDiff -1.8 to -0.2 3.1 to 5.2 § 7.7 to 3.5

PI:PIV PltPIII NoDiff -1.3to1 NoDiff NoDiff 1.1 to4.2§ NoDiff 0.9 to 3.3 § NoDiff NoDiff NoDiff NoDiff 47.2 to 47.7 5.9 to 8.4 § NoDiff NoDiff 1.1 to-1.2t -5.1 to -4.3 5.1 to 6.9 7 to 8.8 NoDiff NoDiff -1. 8 to -4.3 § NoDiff NoDiff 7.7 to 12.7 § NoDiff

PI:PV NoDiff -2.9 to 2 NoDiff NoDiff NoDiff 47.2 to 47.8 5.9 to 2.1 NoDiff NoDiff NoDiff NoDiff NoDiff 7.7 to 3.4

5. Conclusions Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal position will vary from patient to patient. Future studies are directed at determining the optimal position. 6. Acknowledgements This research was funded by NSERC. Thanks to Luc Dulong for his assistance with the data acquisition. References 1. 2. 3. 4 5. 6. 7.

Relton JE, Hall JE. An operation frame for spinal fusion. A new apparatus designed to reduce haemorrhage during operation. J Bone Joint Surg Br 1967 May;49(2):327-32 Callahan RA, Brown MD. Positioning Techniques in Spinal Surgery. Clinical Ortho. and related research. 1981 Jan/Feb 154:22-26 Guanciale AF, Dinsay JM, Watkins RG. Lumbar Lordosis in Spinal Fusion: A Comparison of Intraoperative Results of Patient Positioning on Two Different Operative Table Frame Types. Spine. 1996. 21(8)964-969. Peterson MD, Nelson LM, McManus AC, Jackson RP. The Effect of Operative Position on Lumbar Lordosis. A radiographic Study of Patients Under Anesthesia in the Prone and 90-90 Positions. Spine 20(12) 1419-1424, 1995. Tan SB, Kozak JA, Dickson JH, Nalty TJ. Effect of Operative Position on Sagittal Alignment of the Lumbar Spine. Spine 19(3)314-318, 1994 Delorme S, Labell H, Poitras B, Rivard CH, Coillard C, Dansereau J. Pre-, Intra-, and Postoperative Three-Dimensional Evaluation of Adolescent Idiopathic Scoliosis. Journal of Spinal Disorders. 2000 13(2):93-101 Mac-Thiong J-M, Labelle H, Vandal S, Aubin C-E. Intra-Operative Tracking of the Trunk during Surgical Corrections of Scoliosis: A feasibility Study. Computer Aided Surgery. 5:333-342 2000

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Joint Segmental Kinematic Trunk Motion and C.O.P. Patterns for Multifactorial Posturographic Analysis Moreno D'Amico1"2 and Piero Roncoletta2 'Centra Valutazione Patologie Vertebrali - Riabilitazione S. Stefano Via Aprutina 194, 62016 Porto Potenza Picena -MC, Italy 2 Bioengineering & Biomedicine Company Sri Via Atemo 154, 66020 S. Giov. Teatino CH, Italy Abstract. Measurements of postural sway are used to determine a subject ability to maintain upright stance. In many clinical analyses, postural control measured during a quiet standing provides very useful insights about CNS and Motor control behaviour. The aim of this paper is to present a new posturographic methodology including both classical parameter extraction techniques and new specially developed figuring algorithms, in which both kinematic patterns and ground reaction force COP evolution are jointly processed in order to identify the biomechanical behaviour in particular of the spine at each metameric level for both orthostatic posture and lateral bending test.

1. Introduction The maintenance of a stable posture is essential to all humans. The fact that the legs and feet provide a narrow base of support, makes this task quite difficult. This imposes critical demands on the postural and balance control system. Balance is integral to the safe execution of most movements. Measurements of postural sway are used to determine a subject's ability to maintain the upright stance. In this way Posture is a "continuously evolving dynamic event" that can be expressed as a position of the body maintained in space for some time under the continuous control of the Central Nervous System (CNS). Even static posture such as indifferent orthostasis is characterised by an "equilibrium status" and its intrinsic variability in term of oscillations around this status. The intrinsic variability is strictly connected to a given physiological condition (normal, voluntarily maintained, fatigued etc.). So changes in postural attitude and their variability are very important parameters in order to quantify the functional action of CNS on the body system [1,2]. An open debate in literature refers to the identification of balance and motor control disturbance in particular at spine level as one of the possible causes of Idiopathic Scoliosis. To study such a pathological aspect of the Spine, it is very important to have the possibility to fully explore and evaluate the individual postural behaviour enlightening in particular rachis function. Many studies presented in literature describe a variety of postural characterisation analyses for both orthopaedic and neurologic diseases [1,2], but unfortunately they are mainly limited to ground reaction posturographic approaches often disregarding kinematic segmental body movements. In particular few studies outline, except for gross trunk movement description, the behaviour of spine during body sway. No one at our knowledge details the description at segmental level, limiting the analysis to only COP pattern processing and examination. In order to improve Posture characterisation, we developed a pioneer methodological approach and investigation protocol for segmental analysis to take into account both force platforms and/or

150

M. D'Aiuicii (tnd P Roncoh'ttti / Joint Se\>ineni(il Kincnmtic Trunk Morion

pressure maps COP patterns and opto-electronic 3D kinematic measurements enlightening the contribution at several body levels with a particular focus on the spine.

2. Methods In order to proceed to the joint kinematic and COP patterns analysis, we use both optoelectronic measurement system and force platforms or baropodographic systems. In the protocol adopted we measure the 3-D spatial positions of 27 small passive markers placed on anatomical repere points located on the patient's head, spine, trunk and lower limbs. The vertebral column is identified by 11 markers placed on the spinous processes from C7 down to S3 every second vertebra, while the head, chest and pelvis movements are taken into account by placing markers on the zygomatic bones, chin, sternum, ASIS and PSIS respectively [3,4]. The three dimensional co-ordinates of the markers are measured with an accuracy of 1mm at lOOHz sampling rate by using an optoelectronic posture analyser equipped with two pairs of TV cameras filming the patient's back and front. Vertical ground reaction forces and centre of pressure (C.O.P.) time courses are simultaneously recorded. COP analysis is approached by using bivariate scattergrams statistical techniques. To ensure uniformity with COP pattern analysis, only horizontal plane projections of spatial coordinates are taken into account to extract bivariate scattergrams for kinematic variables. In this case, the correct statistical model is the "correlation statistical model" in which it is generally sought to determine whether two variables are independent or covary. A number of parameters are in general used in descriptive statistics to quantitatively identify scattergrams behaviour and characteristics. A full discussion of such statistics is beyond the aim of this paper, in which only the most important parameters are summarised; the reader can refer to [5] for a complete treatment. The main quantitative parameters used are the so called two principal axes of motion, the equal-frequency ellipses and confidence ellipses. The first ellipse refers to statistical behaviour of the actual sample while the second one refers to statistical characteristics of the bivariate expected mean. The bivariate mean per each variable (and the related standard deviation) are firstly assessed identifying the centre position of the ellipses. The variance-covariance matrix is then determined and its eigenvalues are used both to assess the directions of ellipses major and minor axes and to estimate the level of variability of the considered variables along the latter. The shape of such ellipses is a function of correlation between variables, and the area of the ellipse is a function of confidence coefficient 1 - a. "Equal-frequency" ellipses describe the covariation found in a sample. They enclose about 100(1 - a)% of the observations in the given sample. On the other hand "confidence" ellipses for the bivariate mean are expected to contain the true parametric mean at a 100(1 - a)% probability.

3. Results To illustrate the procedure outcomes, two kinds of postural trials on a 30 years old healthy subject are taken into account: a 10 seconds indifferent orthostasis and a right lateral spinal bending (starting from an indifferent orthostatic standing position untill to maximum lateral flexion). Analysis of orthostatic averaged posture enlightened the subject presented on the frontal plane a slight scoliotic lateral deviation with right convexity at lumbar level, and a slight compensation with left convexity at upper level. Moreover, the subject presented a lateral right global offset. On the sagittal plane, the subject showed the hyper-kyphosis at thoracic level, a forward position of the pelvis and finally a forward global offset. By analysing the directions of the estimated main axes of motion and the dimension of 95%

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equal-frequency ellipses, particularly at spine metameric level (C7 to S3 every second vertebra), compared to force platform COP motion, it is evident how the oscillation of the spine is higher and in different direction with respect to the COP, thus confirming lhat COP analysis alone cannot represent adequately the complexity of motor control applied by CNS to maintain upright stance. This last aspect is proved also in the analysis of the lateral bending test, where the directions of the estimated main axes of motion and the dimension of equalfrequency ellipses of spine landmarks, indicate some «locked and/or push-pull phase» oscillating regions along with movement execution. The COP motion is of course smaller in size in that COP is constrained not to move out of the global feet area support in order to avoid the fall.

Fig. 1 Orthostatic Posture Average Standing Skeleton Model frontal and sagittal view (left panel). Posturographic analysis -95% equal frequency ellipses- of spine (behaviour starting from C7 to S3 every second vertebra) and Force platform COP pattern (last bottom-right box).

Fig. 2 Lateral Bending Skeleton Model frontal and sagittal view (left panel). Posturographic analysis of spine (behaviour from C7 to S3 every second vertebra) and Force platform COP pattern (last bottom-right box).

Conversely, the size of COP motion in relationship with that of other body districts can witness the good quality of CNS control in maintaining balance. Such possibility to subdivide segmental spine and body mobility into congruent movement regions give important insights about CNS motor control actions and balancing adopted strategies, correlating them with individual anthropometrical morphological characteristics.

M. D'Amico ami P. Koncolctui /Joint Scxmcnidl Kinematic Trunk Minion

Fig. 3 Lateral Bending. Posturographic analysis -95% equal frequency ellipses- of spine (behaviour starting from C7 to S3 every second vertebra) and computed angular variations of main ellipses axis directions along each evaluated level

3. Conclusions The presented methodology allows to point out different CNS motor control strategies and provides a powerful tool to better characterise pathological influences enlightening particular segmental behaviour at various body levels. In this sense, it demonstrates to be particularly useful for the study of pathological conditions that can alter static and dynamic balance.

References 1. 2. 3.

4. 5.

F.B. Horak et al., Components of Postural Control in the Elderly: A Review, Neurobiology of Aging, 10:727-738, 1989. D. Winter, Human Balance and Posture Control during Standing and Walking, Gait & Posture 3 (I99S) 193-214. D'Amico M. et al., 3D Spine Morphology Identification by Mean of Parametric Curve Modelling and Self-Adapted Digital Filtering, Proceedings of the 8th Int. IMEKO Conf. on Measurement in Clinical Medicine, Dubrovnik, 16-19 September 1998,1998,8/26-8/31. M. D'Amico et al., A 3-D Parametric BJomechanicaJ Skeleton Model for Posture and Spine Shape Analysis, Proceedings of the 3rd IRSSD Meeting, Clermont-Ferrand France (2000), in press. R. Sokal and J. Rohlf, Biometry The Principles and Practice of Statistics in Biological Research, W.H. Freeman and Company, New York, 1994

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Transverse Plane Pelvic Rotation Measurement Brennen Lucas, Marc Asher, Terrence Mclff, Dick Lark, Doug Burton Kansas University Medical Center, Kansas City, Kansas USA Abstract: Aim: To determine how pelvic rotation in the transverse plane relates to coronal plane anatomical landmark location. The problem this addresses is the observation that iliac crest medial lateral width as seen in the coronal plane Cobb is often asymmetrical in patients with idiopathic scoliosis before treatment, and sometimes after treatment. Materials and Methods: A pelvis was marked with radiographically opaque markers at symmetrical sites in the ilium, sacrum and acetabulum; mounted in a jig; and radiographed at varying degrees of transverse and sagittal plane angulation. The medial lateral distance from two similar landmarks on opposite sides of the pelvis was then determined and a left/right ratio correlated with the degrees of transverse plane angulation. In addition, a theoretically derived equation was developed to describe the effect of pelvic shape on the degree of transverse plane rotation. Results: The left/right ratio for the distance from the sacro iliac joint to the anterior superior iliac spine proved to be the most reliable for determining the degree of pelvic rotation in the transverse plane. The relationship is nearly linear up to 2S( rotation and is little influenced by the degree of sagittal plane angulation. Based on theoretical considerations, the importance of the anterior to posterior angular relationship of the two coronal plane landmarks measured influences the degree of rotation but not the linear relationship. Conclusion: Within limits the transverse plane rotation of the pelvis can be determined by a left/right ratio of the distances between two similar landmarks on each side of the pelvis.

1. Aim

For many years we have pursued the concept of idiopathic scoliosis correction as being torsional and countertorsional loads in the transverse plane.1'2 We have reported some success in accomplishing this correction.3'4 In the process we have noted that torsional loads sometimes appear to be translated to the pelvis with postoperative pelvic rotation in the direction of the applied thoracolumbar/lumbar torsion. We have also observed that this transmitted torsion usually appears to lessen or resolve with time. This study addresses how to determine the relationship between pelvic rotation in the transverse plane and anatomical landmark location as seen in the coronal plane. 2. Methods & Materials This study was based on the hypothesis that bony landmarks in the pelvis visible in the coronal plane could be determined that would reflect transverse plane rotation. This follows Nash and Moe's experiments on vertebral body transverse plane rotation.5 A pelvis was marked with radiographically opaque markers at symmetrical sites on the ilium at the inferior edge of the sacroiliac joint (I), the lateral most projection of the anterior superior iliac spine (ASIS), the outer superior lateral edge of the acetabulum (A),

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the projected center of the femoral heads (FH), the medial and lateral edges of the obturator foramen (MO and LO), as well as the base of the spinous process at SI (MID). It was mounted in a positioning jig and radiographed posterior to anterior at a tube film distance of 183 cm (72") in varying degrees of transverse, sagittal, and coronal plane angulation. The medial to lateral distances on radiographs from two similar landmarks on opposite sides of the pelvis were measured, and a left/right ratio was calculated and correlated with the degrees of transverse plane angulation. In addition, a lateral x-ray of the specimen was obtained, and two theoretically derived equations were developed to describe the effect of pelvic shape and the location of compared landmarks on the degree of transverse plane rotation. The effect of any intrinsic differences in right to left hemipelvis sides was not studied. 3. Results The left/right ratio for the distances on radiographs from the inferior ilium adjacent to the sacroiliac joint to the anterior superior iliac spine (I-ASIS) proved to be the most reliable for determining the amount of pelvic rotation in the transverse plane. The relationship was nearly linear up to 25° transverse plane rotation and was little influenced by the degree of sagittal or coronal plane angulation or by the vertical location of the x-ray beam, either aimed at the thoracolumbar junction or directly at the pelvis. Based on theoretical considerations, the importance of the anterior to posterior projected transverse plane angular relationship of the two coronal plane landmarks measured influenced the linear relationship of the left-right hemipelvis ratio, the corresponding degrees of transverse plane pelvic rotation, and the linear relationship of the left-right ratio to the transverse plane rotation. For the adult female pelvis model studied, left-right I to ASIS ratios of .5 and .75 approximated 10° and 5° of clockwise transverse plane pelvic rotation and ratios of 2 and 1.3 approximated 10° and 5° of counterclockwise rotation, respectively.

4. Conclusion Within limits the transverse plane rotation of the pelvis can be determined by left-right ratios from the distance between two similar landmarks on each side of a symmetrical pelvis. The most reliable distances we found were the horizontal distance between vertical lines drawn through the inferior edge of the ilium at the sacroiliac joint and the lateral most shadow of the anterior superior iliac spine. To convert the ratios to degrees requires additional, more complex calculations. 5. Acknowledgments The authors wish to thank Terry Orrick, academic secretary, and Barbara Funk, editor, for their assistance in the preparation of this manuscript. This study was supported in part by the Marc A. and Elinor J. Asher Research Endowment at the Kansas University Endowment Association and the Scoliosis Research Fund, Kansas University Surgical Association.

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6. Conflict of interest disclosure See Asher et al: Trunk deformity correction stability... This volume.

References 1. 2. 3. 4.

5.

Asher, M.A.: Isola spinal instrumentation system for scoliosis. In The Textbook of Spinal Surgery. Edited by Bridwell, K.H., and Dewald, R.L. Philadelphia, Lippincott, pp. 569-609, 1997. Asher, M.A., and Burton, D.C.: A concept of idiopathic scoliosis deformities as imperfect torsion(s). Clin.Orthop. 364:11-25,1999. Burton, D.C.; Asher, M.A.; and Lai, S.M.: The selection of fusion levels using torsional correction techniques in the surgical treatment of idiopathic scoliosis. Spine 24:1728-1739, 1999. Gondo, H., and Asher, M.A.: Mid-term effects of Isola instrumentation on the configuration of the spine and the thoracic cage in adolescent idiopathic scoliosis. In Research into Spinal Deformities. Edited by Sevastk, J.A. and Diab, K.M. Amsterdam, IOS Press, pp. 433-436,1997. Nash CL Jr., Moe JH. A study of vertebral rotation. J Bone Joint Surg 51A:223-229,1969.

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Tli.R.Gri\-(i.\tE
ios /Vo.v :tm:

Baropodographic Measurements and Averaging in Locomotion and Postural Analysis Moreno D'Amicouand Piero Roncoletta2 'Centra Valutazione Patologie Vertebrali - Riabilitazione S. Stefano Via Aprutina 194, 62016 Porto Potenza Picena -MC, Italy 2 Bioengineering & Biomedicine Company Sri Via Aterno 154, 66020 S. Giov. Teatino CH, Italy Abstract. The use of quantitative baropodography measurements, either by means of-pressure sensing foot insoles or floor mats, is quickly increasing in clinical and research fields for the analysis of a wide variety of foot and ankle disorders. In this paper we present a set of complex and detailed processing procedures necessary to correctly perform gait cycles normalisation and averaging as well as bivariate statistic for COP analysis, in order to extract quantitative and statistically significant parameters for clinical evaluation of locomotion and orthostatic posture.

1. Introduction Baropodography is an approach that allows to study and inspect a wide variety of foot and ankle disorders. The study of underfoot load distribution is very important to determine posture balance and compensatory strategies in the body system, given the strict link between the forces generated through the feet during locomotion or in static posture and forces exerted on all the body and in particular on spine [1]. The intrinsic variability connected to posture, gait or to any other motor task (both normal and pathological one), implies the necessity to approach biomechanics of movement in terms of the identification of an average behaviour and a band of variability around the latter. This concept is the basis of the general approach our group is working on since many years to establish a set of general algorithms and mathematical/statistical tools for the quantitative study of movement and posture. Multifactorial approach is the term used to express the necessity to perform biomechanical analysis by collecting sets of different variables from several measurement devices and to elaborate them within a well established framework. The aim of this paper is to present the necessary methodological approach we had to develop in order to integrate baropodographic measurements into the above mentioned general framework to consider average behaviour. Underfoot pressure maps measurements allow to identify foot/floor interaction and foot mechanics from which it is possible to study upper level biomechanical behaviour during locomotion and orthostasis. Unluckily, pressure maps measurement systems do not allow to collect shear forces, so the optimal condition would be to simultaneously record data from both baropodographic systems and 3D force platforms. Anyway, a joint analysis of baropodographic and force platform data is beyond the aim of this paper and will not be hereinafter discussed. Several different commercial devices are available for the collection of raw pressure maps, but, to author's knowledge, no one of these allows to perform averaged and normalised analysis by means of robust signal processing algorithms, except for a subset of specific parameter (peak pressures, peak forces and so on), hi order to reach the goal to analyse mean behaviour it has been necessary to define a set of biomechanical parameters to properly describe stride and gait cycles and to develop a set of mathematical procedures to perform a rigorous time normalisation and averaging. In the results section, the outcomes of

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such developed methodological approach joined to kinematic analysis within the multifactorial general framework will be presented for posture and gait.

2. Method Our experimental set-up is based on F-Scan foot pressure insole/mat systems by Tekscan Inc., in any case the methodological approach is a very general one. Each insole consists of a matrix of load pressure cells and it works at a given sampling rate. The usual raw measurement data consist of a set of pressure distribution maps obtained indifferently from normal floor or treadmill walking. Different mathematical approaches have to be used to proceed into orthostatic posture analysis or gait analysis, needing this latter a more complex data treatment. In Orthostatic posture analysis the clinical/biomechanical interest is focused on the dynamic activity expressed as a postural body sway. Usually both feet are simultaneously loaded and the variability in load level and underfoot distribution represents the continuous action of the CNS motor control over all the body system to maintain orthostatic standing position. For this particular condition, given the fact the feet are continuously in contact with the floor, if they are not moved during the data acquisition process, the averaging can be directly applied on each cell of pressure to extract a mean underfoot loading behaviour, expressed by mean pressure maps as well as mean vertical forces patterns. Moreover, it is also possible to use advanced statistical techniques of bivariate scattergrams [2] for the analysis of C.O.P. traces, allowing to extract a number of statistical parameters, such as equal frequency and confidence ellipses, regression lines and coefficients, correlation coefficients, main axes of motion. By comparing these findings from both feet and also studying their evolution during body sway, relevant information about posture stability and repeatability are obtained.

Fig.l Stride definition, please note that in second panel horizontal axis represents time, so feet contacts are shown as they appear in time and not in their positions along pathway as shown in the upper panel

In gait analysis, we proceed to assess the sought average behaviour by defining and estimating the mean stance phase for both the feet and then composing them into an average stride (gait cycle), by computing all the averaged timing per each identified "sub-action" expressed along the movement execution. In fact gait is subdivided into strides. The Stride is defined as the sequence of "sub-actions" in between a heel contact and the following heel contact of the same foot [3]. A short discussion follows on Stride definition and on a choice

1 5X

M D'Amico and P. Rtun olcrta / HaropiHlo^raphu Mcuxuremcnts and Avera^im*

we made in order to maintain a clear symmetrical graphical representation. Starting for instance from the Left foot initial contact (fig. 1), we have the following timing phases ("subactions") to be considered: double support (from Left foot initial contact - LIC - to Right foot toe off - RTO), Left single foot stance (from RTO to Right foot initial contact - RIC), double support (from RIC to Left foot toe off - LTO), Right single foot stance (from LTO to LIC), double support (from LIC to RTO). As you may note in this way we refer to an "extended" definition of Stride; in fact, the last double support phase (from LIC to RTO) is not included in a Stride given its definition, as it belongs to the next Stride being its first double support phase. This choice does not affect the computations but it is very useful in order to maintain a graphical symmetry, giving the possibility to represent the complete stance phases for both the feet. When the following stride is represented the first DS is exactly the last of its previous stride. On an average "Extended Stride" it follows from the above definitions that first and last average DS are equal in time. From the recording of multiple gait cycles, the developed procedure automatically identifies strides and their sub-phases. Intrinsic gait variability implies that one stride lasts differently from another. Given the fixed measurement sampling rate, before proceeding to "averaging", it follows the necessity of data re-sampling per each stride temporal phases, in order to obtain the same number of samples for the variable courses of interest. This is necessary in order to avoid to erroneously average not congruent time events on different strides. This re-sampling is a very delicate step in the data processing flow and given its strict connection with signal smoothing interpolation and fitting, very big problems can arise if the re-sampled variables have to be further processed, in particular if they have to be differentiated. This collection of procedures is defined as Time Normalisation. The peculiarity of the presented method is related to the use of a specially improved version of the signal processing procedure we developed in the past for Biomechanical data processing and parameters extraction[4,5]. It allows to correctly interpolate/fit variables time courses with a very high time resolution even for very short phases, as the double support ones, simultaneously guaranteeing an automatic and very accurate signal smoothing and derivatives assessment [6]. Per each stride phase, the mean duration value is computed for all the considered gait cycles and used as base for time normalisation. After time normalisation the averaging process starts. It is divided in 2 sub-steps: at first the Mean Stance Phase is computed; second the Mean Stride is computed on the basis of Mean Stances of both feet and all Ihe other averaged time events. In this way the mean stride is correctly defined as the one having each frame as the result of the previous normalisation and averaging process. Each Mean Stance Phase is to be considered as two parallel sequences of frames, the first one, built by assigning to each cell the obtained average values, the second one built by assigning to each cell standard deviation values. Finally all the mean normalised time variables (see results) as well as COP patterns bivariate statistic can so be extracted from the Mean Stride. We remind that such approach is a general one and can be extended also to different motor tasks such as run, jump etc, given the correct identification of the movement and its breaking up into "sub-actions".

3. Results Once the previously defined mean gait cycle is computed, a set of statistically significant biomechanical and clinical parameters are extracted to perform an in-depth analysis to be used for inter- or intra-subject evaluations. Among them, we remember the mean and standard deviations of C.O.P. trajectories, C.O.P. speeds and accelerations, mean and standard deviation of vertical forces patterns and their first and second time derivatives (namely, Rate of Force Variation and Velocity of Rate of Force Variation), and many others. These variables are computed both for the pressure map related to the whole foot, and for smaller subsets of

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pressure cells, defined as Regions of Interest, related to specific foot anatomic parts such as heel, mid and forefoot and so on. A new introduced special graphical feature for gait analysis is the so called "butterfly" window. It is related to the "Extended Stride". This graphic is obtained by a spatial weighted baricentre of both feet COPs actual positions (feet are considered as they were symmetrically positioned); this pattern allows an intuitive and immediate evaluation of the symmetry of subject's gait. To represent map pressures of stance phases, the so called "peak frames" are used. They are defined as the maps obtained by assigning to each pressure cell the peak pressure value reached during stance. In order to perform data elaboration and to present in a user-friendly format the obtained results, a specially developed software package has been developed. The software also gives the user a high capability of interaction, a very important feature by considering that the presented approach can be applied to the analysis of extremely different motion tasks.

Fig. 2. Orthostasis of a scoliotic patient having a 1 cm. leg length discrepancy, being the left the shorter one.

The figures report a typical set of the outcomes of the presented multifactorial approach. A scoliotic patient presenting a 1 cm. leg length discrepancy, being the left leg the shorter one has been evaluated both in static and in dynamic condition using opto-electronic 3D kinematic measurements following the protocol presented in [7,8] and baropodography. The analysis of orthostatic posture (Fig. 2) enlightens on the frontal plane a left convex scoliotic curve at lumbar level with a minor thoracic compensation as well as a complete global offset to the left side. On sagittal plane a slight backward global offset and a tendency to hyper-kyphosis and hyper-lordosis are evident. Pressure maps and derived vertical forces show a higher load on the left foot and also a higher load on both the heels with respect to forefeet. COP bivariate analysis reveals higher oscillation on right foot with a main extrarotated load direction. The analysis of the measured vertical forces in locomotion (Fig. 3) reveals a different load between feet, being the right more loaded along with the various gait cycles (upper panel). Butterfly window in the middle of lower panel gives an intuitive evaluation of gait symmetry being the left foot stance duration time, longer than the right one. Mean Stride pressure maps and vertical forces assessment (Fig. 4) of the above locomotion (upper panel) confirm the mean higher load on the right foot while their associated s.d. enlighten the different feet control ability of the subject, being the right foot stance pattern with a lesser level of repeatability. Moreover a different load transfer pattern heel to forefoot is evident in between the right and left foot. Pressure maps enlighten the different loading patterns in each foot showing the pressure concentration in different foot regions.

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4. Discussion and Conclusion The burden of such complex processing is justified by the peculiarity of the obtained results. In fact, in this way, the true mean gait cycle phase can be correctly identified. By the analysis of its time courses variations and of all the possible derived parameters, the foot/floor interaction investigation can rely on a statistical significance that improves the clinical and biomechanical reliability and understanding of the obtained results. The proposed method allows to obtain a mean gait cycle phase each frame of which is obtained as a complex, mathematically rigorous averaging process. We propose this approach to increase the statistically significance of foot/floor interaction analysis.

Fig. 4. Mean Stride pressure maps and vertical forces assessed from the above locomotion. (See text)

M. D 'Ainico and P. Roncolelta / Baropodographic Measurements and A veragin}>

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References 1.

2. 3. 4.

5. 6.

7. 8.

P. Dangerfield et al., Gait Analysis ogf Patients with Adolescent Idiopathic Scoliosis, Three Dimensional Analysis of Spinal Deformity (Eds. M. D'Amico et al.) Proceedings Of the 2nd Int Sym. On 3D Scoliotic Deformities, Pescara 1994, IOS Press, 1995,297-301. R. Sokal and J. Rohlf, Biometry The Principles and Practice of Statistics in Biological Research, W.H. Freeman and Company, New York, 1994 M. Whittle, Gait Analysis An Introduction, Butterworth-Heinemann, Oxford, 1996. M. D'Amico and G. Ferrigno, Technique for the Evaluation of Derivatives from Noisy Biomechanical Displacement Data Using a Model-Based Bandwidth-Selection Procedure, Med. & Biol. Eng. & Comput 28, pp. 407-415 (1990). M. D'Amico and G. Ferrigno, Comparison between the More Recent Techniques for Smoothing and Derivative Assessment in Biomechanics, Med. & Biol. Eng. & Comput 30, pp. 193-204 (1992). M. D'Amico and P. Roncoletta, A Self-Adapted Filtering Procedure for Normalisation and Averaging, IFMBE Proceedings of the 9th Mediterranean Conference on Medical and Biological Engineering and Computing, Pula Croatia (2001), pp.6-41 - 6-44. M. D'Amico et al., A 3-D Parametric Biomechanical Skeleton Model for Posture and Spine Shape Analysis, Proceedings of the 3rd IRSSD Meeting, Clermont-Ferrand France (2000), in press. M. D'Amico, Algorithm for Estimation, Classification and Graphical Representation of Clinical Parameters in the Measurement of Scoliosis and Spinal Deformities by Means of Non-Ionising Device, in Three Dimensional Analysis of Spinal Deformity (Eds. M. D'Amico et al.) Proc. Of the 2nd Int Sym. On 3D Scoliotic Deformities Pescara Sep. 94, IOS Press 1995,33-38.

Movement analysis of scoliotic subjects using Fastrak Aziz Rahmatalla ', Nachiappan Chockalingam 2'3, Peter Dangerfield 3, El-Nasri Ahmed ', Tom Cochrane2, John Dove ' and Nicola Maffulli l ' Hartshill Orthopaedic Centre, North Staffordshire Hospital, Stoke on Trent ST46QG 2 School of Health, Staffordshire University, Leek Road, Stoke on Trent ST4 2DF 3 Departments of Clinical Anatomy and Cell Biology and Musculo Skeletal Medicine, University of Liverpool, Liverpool L69 3GE

Abstract. An attempt has been made to simplify the measurement of composite movement involving abnormal rotation in scoliosis, which is considered to have an important role in the diagnosis and treatment of the condition. Analysis of three-dimensional movement provides pertinent information concerning the morphological description of scoliotic deformities. The description of this movement is of clinical interest for aiding diagnosis and/or prognosis of spinal deformity evolution. Previous studies have indicated that idiopathic scoliosis is a three-dimensional deformity accompanied by a generalised torsion phenomenon and attempts have been made to associate the geometric torsion index with the curvi-linear shape of idiopathic scoliosis. Although previous investigations have documented the three-dimensional reconstruction of scoliotic spine, most methods either expose the subject to a high level of radiation, as in stereo-radiographs, or demand a high degree of technical input and time, as in video based gait analysis systems. This study employs an electro magnetic field capturing system (FASTRAK) to estimate the spinal movements. This simple system is inexpensive and highly portable. Furthermore, it can give instant graphic and numerical values of the composite movement. The results of this study indicate the usefulness this system in the diagnosis of scoliosis and highlights the possibility of its uses in screening school children and other surveys.

1. Introduction Although previous studies have successfully demonstrated 3D reconstruction of the spine from radiographs [1], there remains a need to evolve a non-invasive measurement that would describe the configuration of the scoliotic curve in three dimensions. A number of non-invasive measurements have been reported including the use of Scoliometer (I SI Instruments) [2], formulator [3], electrogoniometer [4] and other electromagnetic techniques [5]. Some of these measurements have been criticised for their poor precision and inadequate diagnostic accuracy [2]. While most studies focussed primarily on the resultant back surface shape and rib hump geometry, Pearcy [5] demonstrated the efficient use of electromagnetic techniques to obtain accurate and reliable results for trunk measurements. Smidt [6] reported a potentiometer system to study range of movement and spine configuration. While indicating that the thoraco-lumbar ranges of motion for scoliotics and normals were similar, this study observed similar effects for normals and scoliotics in a variety of seated positions.

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Previous investigations have examined the coupling motion in the thoracic spine and demonstrated a repeatable upper thoracic movement pattern within and between subjects [7]. Commercially available non-invasive electromagnetic systems measure the position and orientation of a skin mounted sensor (receiver) relative to a fixed source (transmitter) in space. These systems demonstrate high resolution, good accuracy and repeatability. However, as in other skin marker based systems, accuracy is affected by the skin movement artefacts [5]. 2. Methods The Fastrak electromagnetic tracking system (Polhemus Navigation; Colchester, VT, USA), which has been described elsewhere, [8] was used for this study. 9 patients (3 males and 6 females) with a mean age of 15 years (range 12-20) participated in the study. Data was collected from four receivers attached to the skin by strips of double sided adhesive tape over the spinal processes of C7, T6, T12 and SI. The patient was asked to perform three cycles of maximum flexion/extension, right and left side lateral bending and right and left rotational movement at their own pace. . The study received approval by the local Ethics Committee.

3. Results

left axial rotation

right axial rotation

Time Figure 1: Graphical display of the movement at C7, T6, T12 and SI at the dominant planes

Figure 1 indicates results from a typical trial. The first three cycles represents movement during flexion and extension. The second shows the movement of the right and left lateral flexion. The last three cycles represent the right and left axial rotation. All measurements started from the zero position and the actual angles at the start point were recorded. The pattern of movement and the associated symmetry between the right and left sides between and across subjects as well as the ratio between the dominant and minor movement in different planes were investigated. Figure 2 shows the comparison between dominant and coupling movement at various joints and the table 1 shows the range of motion at various levels.

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c7 flex/ext

c7 lat bending c7 rotation T6 flex/ext

T6 lat bending T6 rotation Tl2 flex/ext

Tl 2 lat bending \ Tl2 rotation si flex/ext

si lat bend Figure 2: 3-D display of dominant and couplings movemen

si rotation

Table 1: Mean values in degrees of spinal movement of 9 cases C7

T6

T12

SI

Flexion

109.27

109.77

80.49

49.21

Extension

27.01

23.56

14.95

11.83

Right bending

50.85

40.07

20.65

10.34

Left bending

47.89

41.50

19.48

12.15

Right rotation

94.65

73.03

64.62

63.04

Left rotation

87.59

75.63

57.11

55.07

Figure 3

Figure 4

•

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Figure 5

Figure 7

165

Figure 6

Figure 8

Figures 3 to 8 show the graphical representation of various movements ie flexion, extension, right lateral bending, left lateral bending, right axial rotation and left axial rotation respectively at different levels of the spine. Figures 9 and 10 shows the composite movement during lateral flexion at T6 and T12 respectively.

4. Discussion

Figure 9

Figure 10

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A. Ruhmatalla et al. /Movement Anal\sis of Scoliotic Subjects using Fastrak

Spinal deformity is characterised by 3-D changes in the spinal column. Therefore any correction of such a deformity requires accurate assessment of any changes to the normal spinal curvatures such as lordosis and kyphosis, or detecting abnormal structural changes such as rotation. Existing methods either allow 2-D static analysis or expose the patients to a high level of radiation [5]. Video and camera tracking systems provide threedimensional analysis but these techniques are expensive, time consuming and require high technical skill to operate. With the introduction of electromagnetic tracking systems, movement analysis, with a capability of computing with 6 degrees of freedom (3 translational and 3 angular orientations in real time), is now possible. These systems have been used in other fields such as animation, navigation, and virtual reality applications. The results of the present study have demonstrated good reproducibility over number of cycles. The investigation has examined the pattern of movements and the relationship between the dominant plane and coupling movement. Preliminary results indicate that there is excessive rotational coupling, and to a lesser degree, flexion during right and left lateral bending at T6 and T12. There are no reciprocal movements during rotation and this may prove to be significant in clinical conditions. Although previous studies have compared Fastrak and a similar potentiometer based (CA6000: Spine Motion Analyser) system and demonstrated a good test-retest reliability, no conclusive evidence is reported on the accuracy of measurement of true angular movements of the vertebrae [9]. Frontal plane angles were comparable between both systems but the sagittal and transverse plane angles were significantly different. However, Mannion and Troke (1999) compared only lumbar segment range of movement and the values could be different for thoracic region, which is not, reported anywhere. The Fastrak system, reported in this study, may provide the solution to the need for inexpensive, simple and portable tools which can be used for surveying technique outside hospital and clinics. The system also has a high degree of accuracy and good inter- and intra- reliability and reproducibility [8,9]. References 2

M. J. Pearcy and S. B. Tibrewal, Axial Rotation and Lateral Bending in the Normal Lumbar spine measured by three-dimensional radiography. Spine 9(6) (1984) 582-587. 3 P. Cote, B. G. Kreitz, J. D. Cassidy, A. K. Dzus, J.A. Martel, Study of the diagnostic accuracy and reliability of the scoliometer and Adam's forward bend test. Spine 23 (1998)796-803. 4 P. H. Dangerfield, J. S. Denton, S. B. Barnes, N. B. Drake, The assessment of rib cage and spinal deformity in scoliosis. In I A F Stokes et. al., eds. Surface topography and spinal deformity: Gustav Fischer Verlag, Germany. 1987, pp. 53-66. 5 W. S. Man-as, M. Pamianpour, J Y Kim, S. A. Ferguson, R. R. Crowell, S. R. Simon, The effect of task asymmetry, age and gender on dynamic trunk motion characteristics during repetitive trunk flexion and extension in a large normal population. IEEE transactions on Rehab. Eng. 2 (1994) 137 - 146. 6 M. J. Pearcy, R J. Hindle, New method for the non-invasive three dimensional measurement of human back movement Clinical Biomechanics 4 (1989)73-79. 7 G. L. Smidt, S. E. VanMeter, M. D. Hartman, S. E. Messaros, D. L. Rubsam, K. A. Welle, Spine configuration and range of motion in normals and scoliotics. Clinical Biomechanics 9 (1994)303-309. 8 D. Theodoridis and S. Riston, The effect of shoulder movements on thoracic spine 3D motion. Clinical Biomechanics 17 (2002) 418-421. 9 K. Jordan, K. Dziedzig, P.W. Jones, B.N. Ong, P.T. Dawes,. The reliability of the three-dimensional FASTRAK measurement system in measuring cervical spine and shoulder range of motion in healthy subjects. Rheumatology 39 (2000) 382-388. 10 A. Mannion and M. Troke, A comparison of two motion analysis devices used n the measurement of lumbar spinal mobility. Clinical Biomechanics 14 (1999)612-619.

Tli.B.Gm-as(Eci) Research into Spinal Deformities 4 1OS Press, 2002

167

Motion segment stiffness measured without physiological levels of axial compressive preload underestimates the in vivo values in all six degrees of freedom Mark G. Gardner - Morse, Ian A. Stokes , David Churchill, Gary Badger Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall, Burlington, Vermont 05405-0084, USA Abstract: Axial preload is known to alter the mechanical properties of spinal motion segments. The objective of this study was to compare the experimentally measured loaddisplacement behavior (stiffness, hysteresis and linearity) of porcine lumbar motion segments in vitro with physiological axial compressive preloads of 0, 200 and 400 N equilibrated in a physiological fluid environment. At each preload, displacements in each of six degrees of freedom (±0.3 mm AP and lateral translations, ±0.2 mm axial translation, ±1° lateral bending and ±0.8° flexion/extension and torsional rotations) were imposed. The resulting forces and moments were recorded. Tests were repeated after removal of posterior elements. Using least squares, the forces at the vertebral body center were related to the displacements by a symmetric 6x6 stiffness matrix. The stiffness, hysteresis area and linearity of six diagonal and two off-diagonal load-displacement relationships were examined for differences between preload conditions. Results: Mean values of the diagonal terms of the stiffness matrix for intact porcine motion segments increased significantly by an average factor of 2.2 and 2.9 with 200 and 400 N axial compression respectively (pO.OOl). Increases for isolated disc specimens averaged 4.6 and 6.9 times with 200 and 400 N preload (p<0.001). Changes in hysteresis correlated with the changes in stiffness. The load-displacement relationships were progressively more linear with increasing preload (IT = 0.82, 0.97 and 0.98 at 0, 200 and 400 N axial compression respectively). Motion segment and disc loaddisplacement behaviors were stiffer, more linear and had greater hysteresis with axial compressive preloads.

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M.G. Gardner-Morse el til. /Morion Segment Stiffne:

1. Introduction The biomechanical behavior of the spine can be analyzed by considering it as a column of motion segments, each with defined mechanical properties. Accurate analyses of spine behavior therefore require accurate load-displacement properties of the individual motion segments. Axial compressive preload has been observed to increase motion segment stiffness by a factor of two or more for human lumbar motion segments [1,2]. However, the effect of preload on other aspects of the motion segment loaddisplacement behavior has not been reported. This study was designed to investigate how the load-displacement behavior of motion segments about the neutral posture varies with axial compressive preloads under conditions that aimed to simulate in vivo conditions of loading and fluid environment. Specifically we tested the hypotheses that motion segment stiffness increases, load-displacement behavior is more linear and hysteresis increases with axial compressive preloads. Also, we tested whether these effects are present in isolated intervertebral discs as well as in intact motion segments. 2. Methods Each of six porcine lumbar segments (all animals over 16 weeks old) was embedded in polymethylmethacrylate cement and attached to end-fittings. Biplanar radiographs were used to align the specimen's local axis system (based on the vertebral body centers) with the centers of the end-fittings. The load-displacement behavior was measured directly in six degrees of freedom (6-DOF) by the method of Stokes et al. [3] that uses a 'Steward platform' or 'hexapod* robot to displace the upper end of the motion segment relative to its lower end that was fixed to the base of the apparatus. The upper end of the specimen was fastened to a 6-DOF loadcell that was mounted under the moving platform. All rotational displacements occurred about the center of the upper vertebral body. Forces recorded by the loadcell were transformed to this same point. Specimens were immersed in an isotonic saline bath cooled to approximately 4°C to slow the biological degradation of the specimens over the 76 hour duration of testing of each specimen. Axial compressive preloads of 0 N, 200 N and 400 N were applied. At 400 N preload, the compressive stress was approximately 0.5 MPa. The are six permutations of possible preload loading sequences and each was used once for each of the six specimens. The specimen was allowed to equilibrate with these preloads for at least three hours before any stiffness measurements were gathered. Six pure displacement tests (four sawtooth cycles each of three translations and three rotations) were then sequentially imposed (each cycle took 87 seconds), and the applied forces and moments were recorded every second. The maximum displacements were ±0.3 mm in the AP and lateral translations, ±0.2 mm in axial translation, and ±1 degree in lateral bending and ±0.8 degree in flexion/extension and torsional rotations. After testing the intact motion segment, the posterior elements (facets and ligaments) were removed and the tests were repeated on the isolated disc.

M.G. Gardner-Morse ct til. /Motion Segment Stiffness

169

For the stiffness properties, forces were assumed to be linearly related to the displacements by a symmetric 6x6 stiffness matrix which was estimated by least squares [3]. Considerations of the sagittal plane symmetry and beam-like behavior of the motion segment permitted reduction of the number of analyzed coefficients to six diagonal terms and two "primary" off-diagonal terms as defined by Goel [4]. The load-displacement recordings associated with each of these eight stiffness components were further analyzed to obtain measures of linearity of the loaddisplacement relationship, using the coefficient of determination (R2). To remove the variation associated with hysteresis, the analyses were done separately for the increasing and decreasing displacements of the four cycles of each recording. The hysteresis was evaluated as the enclosed area in the load-displacement recording for the second and third displacement cycles. Differences in stiffness coefficients, linearity and hysteresis area with preload were analyzed using repeated-measures ANOVA both for intact motion segments and for isolated discs. The significance level for all statistical analyses was set at p=0.05. To estimate the contribution of the posterior elements to motion segment behavior with increasing preloads, the stiffness and hysteresis area of the isolated discs were subtracted from those of the intact motion segment to estimate the stiffness and hysteresis area of the posterior elements. Then the effect of the preload was partitioned between the disc and the posterior elements by regression analysis. 3. Results Increased preload produced progressively increased stiffness in all eight stiffness terms. Mean values of the six diagonal terms of the stiffness matrix for intact motion segments increased by an average factor of 2.2 and 2.9 from the no-preload condition with 200 and 400 N compression respectively (p<0.001). After removal of the posterior elements (i.e. for isolated discs), the diagonal terms of the stiffness matrix increased by a mean 4.6 and 6.9 times compared to the no-preload condition with 200 and 400 N preload (pO.OOl). The trend of increasing stiffness with preload was highly significant for both intact motion segments and isolated discs for all eight stiffness terms (p_0.003). The two primary off-diagonal stiffness terms behaved similarly to the diagonal stiffness terms. These terms increased significantly (pO.OOl) by an average factor of 1.4 and 1.6 with 200 and 400 N preload respectively for intact motion segments and by a mean 3.5 and 5.4 times with 200 and 400 N preload for isolated discs. There appeared to be a tendency for the stiffness increase with preload to be less when preload was increased from 200 to 400 N, compared to the increase from 0 to 200 N. However, this observed nonlinear effect was only significant for the case of axial stiffness, and this was found in both intact motion segments and in isolated discs.

M (I ("mrdner-Mome et al /Motion Segment Stiffnes

Figure 1 Mean and standard error of diagonal terms and primary off-diagonal terms of the stiffness matrix for intact motion segments at three levels of axial compressive preload. All eight stiffnesses linearly increased with preload (p<0.001). The increases in stiffness with preload was slightly nonlinear for the axial stiffness (p=0.012).

The linearity of the load-displacement relationships also increased significantly with axial compressive preload. By pooling results for all eight terms in the stiffness matrices, the mean R2 values for intact motion segments were 0.93, 0.95 and 0.96 at 0, 200 and 400 N preloads and R2 = 0.70, 0.95 and 0.96 at 0, 200 and 400 N preloads for isolated discs. Despite the high no-preload values of R2, preloads produced significant further increases in linearity for three of the eight terms for intact motion segments and for all eight stiffness terms of isolated discs. There was a very strong correlation between hysteresis area and stiffness under all testing conditions. The correlation for all six diagonal load-displacement relationships

M.G. Gardner-Morse et at. /Motion Segment Stiffness

171

for intact motion segments ranged from r=0.90 to 0.96 and for isolated discs ranged from r=0.88 to 0.97. Thus, the increases in hysteresis area with preload were of very similar magnitude to those for stiffness. The posterior elements were found to contribute substantially to the stiffness, as well as being sensitive to the effects of preload. Intact porcine specimens were on average 12.2 times stiffer than isolated discs when tested without preload. The addition of preload reduced this mean difference between intact specimens and isolated discs to 4.6 times and 3.6 times stiffer at 200 N and 400 N preload. As expected, the contribution of posterior elements to the stiffness was greatest for axial rotation (10.7 times increase at 400 N preload) and least for axial stiffness (1.01 times increase at 400 N preload). The regression analyses of the disc and posterior elements stiffnesses with preload demonstrated that for most stiffness terms the discs were more sensitive than the posterior elements to the addition of axial preload. In the case of hysteresis, the increase with preload was almost entirely attributable to the disc for the shear and axial displacements and for lateral bending. 4. Discussion It was found that motion segment behavior measured without physiological levels of axial compressive preload underestimates the in vivo values of stiffness and hysteresis in all six degrees of freedom. Load-displacement behavior also was more linear with axial compressive preload. These effects were present in intact motion segments and isolated intervertebral discs. These findings show that the elastic energy storage and energy absorption (damping) that occurs with displacements of motion segments in vivo increases with the magnitude of the prevailing muscle force and other applied loading. Our analyses that partitioned the preload effect between the disc and the posterior elements indicate that both components are affected by preload, but overall the disc's contribution is larger, especially for hysteresis. Similar findings for human lumbar motion segments for the stiffness increase with preload have been reported by Janevic et al. [2], and for the sagittal plane by Edwards et al. [1]. The findings of this study indicate that in vivo axial compressive loading substantially alter both the stiffness and hysteresis (energy absorbing) properties of the spine. The findings suggest that many of the mechanical studies and simulations of human spine function in relation to stability and effects of surgical interventions may have substantially underestimated the contribution of the motion segments. Biomechanical analyses of the spine that are intended to simulate in vivo loading conditions should take these effects into account. 5. Acknowledgements Supported by NIH R01 AR 44119. Richard Single assisted with the statistical analyses. Porcine lumbar motion segments were obtained with the kind assistance of Donita Bylski-Austrow.

I "72

M.C. Gardner-Morse et til. /Motion Segment Stiffnes

References 1. 2. 3. 4.

Edwards WT, Hayes WC, Posner I, et al. Variation of lumbar spine stiffness with load. J Biomech £wg!987; 109:35-42 Janevic J, Ashton-Miller JA, Schultz AB. Large compressive preloads decrease lumbar motion segment flexibility. J Orthop Res 1991; 9(2):228-236 Stokes IAF, Gardner-Morse M, Churchill D, Laible JP: Measurement of a spinal motion segment stiffness matrix. Journal of Biomechanics, 2002; 35(4): 517-521. Goel VK. Three-dimensional motion behavior of the human spine-a question of terminology. J Biomech Eng 1987; 109(4):353-355

Tli.B. GrmislEd.) Research into Spinal Deformities 4 IOS Press, 2002

Kinematic differences in lower limb gait analysis of scoliotic subjects Nachiappan Chockalingam 1>2, Aziz Rahmatalla3, Peter Dangerfield2, Tom Cochrane ', ElNasri Ahmed 3 and John Dove 1

School of Health, Staffordshire University, Leek Road, Stoke on Trent ST4 2DF Departments of Clinical Anatomy and Cell Biology and Musculo Skeletal Medicine, University of Liverpool, Liverpool L69 3 GE 3 Hartshill Orthopaedic Centre, North Staffordshire Hospital, Stoke on Trent ST4 6QG 2

Abstract. Although various factors have been attributed to the etiology of idiopathic scoliosis, studies have indicated that the kinematic differences in the spine, pelvis and lower limb may contribute to the causation and progression of idiopathic scoliosis. The aim of this investigation was to identify asymmetries in lower limb kinematics and pelvic and back movements during level walking in scoliotic subjects that can be related to the spinal deformity. The study has employed a movement analysis system to estimate various joint angles in the lower extremities and other kinematic parameters in the pelvis and back. The results of a pilot study have highlighted the potential usefulness of a range of parameters in the indication of asymmetries and their implications for spinal deformity generation. While demonstrating the value that movement analysis systems may have in investigating pathogenesis and aetiology, these preliminary findings indicate that the identified variables can also used in the kinematic analysis of spinal deformities such as scoliosis. Further studies are being undertaken to validate these findings.

1 Introduction Detailed biomechanical description of normal and pathological gait is now possible with the help of gait analysis. Furthermore, gait analysis has now become a useful clinical tool providing an accurate three-dimensional measurement of gait [1]. Gait Analysis combined with optoelectronic systems would be useful, since it has a minimal interference in the walking pattern of a person [2]. Previous studies have investigated the factors responsible for the progression of normal gait [3] and the characteristics of pathological gait [4]. A number of studies have demonstrated the value of gait analysis in understanding the etiology of idiopathic scoliosis [5]. Scoliosis affects the physical orientation of the shoulders and head to the pelvis and lower extremities. Although previous investigations indicate the asymmetric growth of the vertebrae as a factor responsible for scoliosis [6,7,8] and the existence of a relationship between lateral flexion and axial rotation [9], the interaction between vertebral deviation and axial rotation is not fully understood [10]. Studies indicate that the causation and progression of idiopathic scoliosis is still unclear [11,12]. However, a recent extensive review indicates possible aetiological factors [13]. Furthermore, several reports suggest a lack of understanding in the pathomechanics of scoliosis progression deters the scientific treatment process [14].

I 74

,V. Clu>ck(ilini>am cr ai / Kinematic Differences in Lower Limb Chut An
Most previous investigations quantifying spinal deformities and the range of movement in the spine and trunk have concentrated principally on spinal/back movement. Measurements are undertaken with the subject maintaining a stationary position while performing tasks such as forward and lateral bending [15,16]. While investigating the synchrony of pelvic and hip joint motion during walking, Crosbie and Vachalathiti [17] suggested there was evidence of a consistent temporal relationship within some of the movements, independent of gender or age effects. The study concluded that the expression of the biomechanical determinants of walking ought to include temporal interactions. Research into the patterns and ranges of movement of the lower thoracic and lumbar spinal segments and the pelvis, while walking at two self selected speeds, indicated an increased range of motion in each segment with increased walking speed and significant reduction in spinal range of motion with advancing age [18]. Spinal movements associated with walking are linked to the primary motion of the pelvis and the lower limbs. Crosbie et al.,[19] recorded the movement of spinal segments about three orthogonal axes and observed consistent patterns within and between segments and movements with apparent consequential trunk motion following pelvic displacements. Spinal segments demonstrate movements complementary to the motion of pelvis with respect to spinal flexion-extension and lateral flexion. In reporting spinal movement patterns, Crosbie et al., also indicated the importance of looking at these patterns in a clinical population. Additionally, there is a paucity of data detailing the relationship between various kinematic parameters of the back and lower limb during gait. This is one of the important considerations in the Nottingham theory for spinal curvature generation [21]. Although this hypothesis includes various other factors in the so called "defending system", consisting of discs, ligaments, ribs and neuro-muscular mechanisms, the present study has concentrates on the "inducing system" consisting of the pelvis and spine. As a first step to address and understand this hypothesis, the present study has concentrated on the lower limb kinematics of scoliotic subjects. 2

Methodology

Seven subjects, clinically diagnosed as having Adolescent Idiopathic Scoliosis (AIS), with a mean age of 14.5 years, mean height of 156.65cms and mean weight of 41.7kgs took part in the trials. The study had full approval of the local ethic committee. Kinematic analysis was performed using a six camera motion analysis system. The system employed APAS and APAS Gait (Ariel Dynamics Inc. USA) software to digitise and analyse the data. Cameras were calibrated using a standard steel cube with 12 markers. Cameras were synchronised using a light emitting diode (LED) device and a force platform (AMTI Inc., USA) was used to identify the heel strike during walking. Subjects performed a few trials to get accustomed to the lab environment prior to the data collection session. A Vaughan modified marker set, as shown in figure 1 and fully described elsewhere [20], was used to identify the anatomical landmarks employed in performing the analysis. Same researcher placed the markers every time to avoid any errors and walking data was collected for 5 trials.

N. Chockalingam ct al. / Kinematic Differences in Lower Limb Gait Analysis

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Results and discussion

Various gait cycle parameters are given in table 1 and mean kinematic measurements for various subjects during individual gait cycle are given in tables 2 and 3. These values indicate the maximum range of motion in a particular plane for a specified joint. Recorded gait cycle parameters do not show substantial asymmetries between left and right sides, except for the unloading response in 4 subjects. However there are intersubjects differences which can be attributed to the anthropometric measurements, cadence and gait velocity. Table 2 indicates inter-subject changes in pelvic tilt, obliquity and rotation. Examining the pattern of curves within subjects, indicates a minimal change in tilt and obliquity between the left and right side of the body. However, the internal and external rotation of the pelvis varies within and between subjects. There are pattern differences between the left and right side and the range of movement varies from 4 to 10 degrees. Although further studies are being conducted to validate the findings, these initial results support the theory put forward by Burwell et al., [21]. Table 3 indicates the results of the measurements at the hip. As shown for the pelvis, and taking anthropometric parameters into consideration, there is no substantial difference in the sagittal (Flexion/ extension) plane across and within subjects. However, there are differences in the frontal (adduction/ abduction) and the coronal plane angles (rotation) within and across the subjects. While demonstrating the usefulness of gait analysis in assessing spinal deformities in general and scoliosis in particular, the initial results of this study validate the Nottingham concept of pathogenesis of idiopathic scoliosis. Most published results, including the present study, concentrate on kinematic measurements. However, it would be useful to couple the movement data with force platform data as this would allow insight into the understanding of the relationship between movement patterns and the etiology of scoliosis.

References: 1. 2. 3. 4.

Chockalingam N, Dangerfield P H and Giakas G (2002) Biomechanical clinical assessment: an introduction to gait analysis, British Journal of Therapy and Rehabilitation, 9 (1), pp 15-23. Winter D A (1990), Biomechanics and motor control of human movement, Wiley - Interscience. Rose J and Gamble J G (1994) Human Walking, Willams and Wilkins. Gage, J. R and Koop, S. E (1995) Clinical gait analysis : Application to management of cerebral palsy. In Three Dimensional Analysis of Human Movement. Allard, P., Stokes, I. A. F and Blanchi, J. P (ed.). Human Kinetics, pp. 349-362.

176

5. 6. 7. 8. 9. 10. 11. 12. 13. 14 15. 16. 17. 18. 19. 20. 21. 22. 23 24. 25.

,V. Chockalini>(iii\ i'l al. / Kinematic Diffcrcin-cs

in Li>wci Linih (iitir Annl\'

Swatzky B, Tredwell S, Sanderson D (1997), Postural control and trunk imbalance following CotrelDubousset instrumentation for adolescent idiopathic scoliosis. Gait and Posture 5, pp 116 -119. Roaf R (1963) The treatment of progressive scoliosis by unilateral growth arrest . J. Bone and Joint Surgery 45 B: pp 637-651. Stokes I A F, Dansereau J, Moreland M S (1989). Rib cage asymmetry in idiopathic scoliosis. J Orthop. Res. 7: pp599-606. Tadano S, Sakai K, Kanayama M, Ukai T, Kaneda K (1994). Finite element simulation in the progression of idiopathic scoliosis. Second World Congress of Biomechanics. Veldhuizen A G, Scholten P J M (1987). Kinematics of the scoliotic spine as related to the normal spine. Spine 12: pp852-858. Stokes I A F, Gardner-Morse M (1991). Analysis of the interaction between vertebral lateral deviation and axial rotation in scoliosis. J Biomechanics 24: pp753-759. Sevastik J A (1987). Idiopathic Scoliosis. What is it ? In: Research into spinal deformities, ed by Sevastik J A, Diab K M. IOS Press. pp37-40. Stokes I A F (1997) Analysis of symmetry of vertebral body loading consequent of lateral spinal curvature. Spine 22: pp2495-2503. Burwell R G, Dangerfield P H, Lowe T G , Margulies J Y (2000). Etiology of Adolescent Idiopathic Scoliosis. State of the art reviews. Hanley & Belfus Inc.,USA. Burwell R G, Dangerfield P H (2000). Adolescent Idiopathic Scoliosis: Hypotheses of causation. In: Etiology of adolescent idiopathic scoliosis. State of the Art Reviews. Ed by Burwell R G, Dangerfield PH, Thomas G L, Margulies J Y, pp319-334. Crosbie J, Vachalathiti R, Smith R (1997). Patterns of spinal motion during walking. Gait & Posture, 5, pp6-12. Stokes V P, Andersson C, Forssberg H (1989). Rotational and translational movement features of the pelvis and thorax during adult human locomotion. JBiomechanics, 22, No (1) pp 43-50. Crosbie J, Vachalathiti R (1997). Synchrony of pelvic and hip joint motion during walking. Gait and Posture 6: pp237-248. Crosbie J, Vachalathi R, Smith R (1997). Age, gender and speed effects on spinal kinematics during walking. Gait and Posture 5: pp 13-20. Crosbie J, Vachalathiti R, Smith R (1997) Patterns of Spinal motion during walking. Gait and Posture 5:pp6-12. Vaughan C L, Davis B L, O'Connor J C (1999). Dynamics of Human Gait, Human Kinetics. Burwell R G, Cole A A, Cook T A, Grivas T B, Kiel A W, Moulton A, Thirlwall A S, Upadhyay S S, Webb J K, Wemyss-Holden S A, Whitwell D J, Wojcik A S, Wythers D J (1992). Pathogenesis of Idiopathic scoliosis: the Nottingham concept, Acta Orthopaedica Belgica, Vol 58, Suppl. 1, pp 33 - 58. Lemmers L G, Sanders M M, Cool J C, Grootenboer H J (1991). The cause of axial rotation of the scoliotic spine. Clinical Biomechanics 6: pp!79 -184. Beck R J, Andriacchi T P, Kuo K, Fermier R W, Galante J O (1981). Changes in the gait patterns of growing children. J Bone Joint Surgery 63 A: pp!452-1457. Elftman, Herbert (1939). The function of the arms in walking. Human Biology 11: pp529-535. Eke-Okoro S T, Gregoric M, Larsson L E (1997). Alterations in gait resulting from delibrate changes of arm swing amplitude and phase. Clinical Biomechanics 12: pp516 -521.

N. Chockalinffcim et al. / Kinematic Differences in Lower Limb Gait Analysis

111

Table 1 : Gait Cycle parameters Subject Loading Single Response Stance Right leg 10.41 1 39.58

Unloading Swing response

Step Cadence Stride Step Stride Duration Duration Length Length 0.48

104.16

1.37

0.57

0.13

1.43

0.5 0.48

96.15 100

1.18 1.16

0.55 0.61

0.1

1.14

0.06

1.16

0.98 1.04

0.5

102.04

1.19

0.58

0.11

1.21 1.14

10.41

39.58

40.38

11.53

36.53

0.96 1.04

3

11.53 14

38

10

38

1

4

10.2

38.77

14.28

2

Step Gait Width Veloi

5

11.53

34.61

17.3

36.73 36.53

0.56

96.15

1.18

0.56

0.07

6

14.06

35.93

14.06

35.93

1.28

0.64

78.12

1.23

0.62

0.09

1.07

7

15.38

34.61

13.46

36.53

1.04

0.52

96.15

0.98

0.52

0.17

0.94

0.48 0.54

104.16

1.28

0.58

0.07

1.34

94.33

1.23

0.68

0.02

1.16

1.42

0.54

0.09

1.4

1.26

0.55

0.09

1.26

Left leg

1

10.41

39.58

8.33

41.66

0.96

2

11.32

37.73

11.32

39.62

1.06

3 4

13.72

13.72

37.25 38

1.02 1

0.52

12

35.29 40

0.48

98.03 100

5 6

12 14.06

40 35.93

12

1

14.06

36 35.93

1.28

0.48 0.64

100 78.12

1.18 1.18

0.54 0.61

0.06 0.06

7

16.66

35.18

14.81

33.33

1.08

0.52

92.59

1.05

0.51

0.07

10

Table 2: Mean Kinematic measurements (Pelvis) Subject

Pelvic Tilt

1

7.8 10.26 4

2 3 4 5 6 7

3.55 4.26 3.07 6.7

Pelvic Obliquity 8.5 8.9

14.54 10.94

Pelvic Rotation 10 8.36 9.91 6.6

5.45

8.18

6.18 5.03

4.88 9.67

Table 3: Mean Kinematic measurements ( Hip) Right Subject

Left

Flexion/ Extension 43 46.26

Adduction/A bduction 11.69 16

Rotation

3 4

41.02

20.9

45.73

5

38.99

6 7

45.1

1 2

41.57

Flexion/ Extension 40.9 47.7

Adduction/A bduction 11.2 15.2

21.7

41.81

20.33

7.53

18.2 11.72

11.18 32.6 15.71

43.76 34.57

15.13 9.25

29.99 11.9

11.4 12.7

15.09 14.14

44.99 38.32

8.18 12.2

9.08 7.39

23.4 24.53

Rotation

22

1.18 0.92 0.97

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Assessing Changes in Three Dimensional Scoliotic Deformities with Difference Maps D.L. Hill, D.C. Berg, T. Church, V.J. Raso Capital Health Authority, Glenrose Rehabilitation Hospital Site, Edmonton, AB Canada dhill@cha. ab. ca Abstract: Topographical difference maps were used to compare the trunk surfaces of subjects over the course of their treatment. Three-dimensional points representing the trunk surfaces were aligned accounting for growth and positioning. A goodness-of-fit score was calculated and a color map used to display trunk surface changes. Fifty-one successive subjects were assessed with difference maps. Two subjects each had 10 repetitions taken on the same day to assess reliability. A blinded observer used a five-point scale that extended from full agreement to full disagrment to judge the maps according to the extent and location of changes. The observations were compared to clinical measures mapped onto the same scale by another blinded observer. Goodness of fit for repeated measures averaged 5+1, for subjects deemed to have no change 7+2, for subjects with slight change 9+2, and 14+2 for subjects with significant change. Judges were in full agreement or in agreemnt with forty of the fifty-one subjects (78%) and in slight disagreement with the remaining eleven. When the cohort was subdivided in surgical, brace and no treatment groups, the judges were in full agreement or in agreement 76%, 80%, and 85% respectively. The difference map provides a qualitative and quantitative measure of how the trunk surface has changed as a whole.

1. Introduction The cosmetic deformity is an important concern to many adolescents with idiopathic scoliosis and often motivates them to seek treatment. Physical measurements consider asymmetries due to lateral sway, trunk rotation, abnormal sagittal profile, as well as waist, shoulder and scapula asymmetries [1]. Change in the deformity, not its absolute measure, provides the important information necessary for making treatment decisions. The physical measurements of the surface deformity do not always adequately describe the changes in deformity over time. Difference mapping provides a holistic technique for examining change in data sets. Early difference mapping in the medical field involved analyzing the shape of pregnant women's abdomens using moire" topograms [2,3]. Qualitative shape analysis has been used to assess the trunk and to compare changes during treatment [4]. More recent work includes the analysis of corneal shape [5] and dentition wear [6,7] using close-range photogrammetry. Elevation deviations are typically displayed as a 3D color-coded difference map to reveal abnormalities. In each of these examples, the surfaces are either compared to an idealized mathematical model, or fitted to previous surfaces with prominent surface features. These surface fitting algorithms are based on minimizing the least squares differences between the surfaces [8]. This works best for fitting surfaces with common landmarks, analytic models or surfaces with steep

D.L Hill et al. /Assessing Changes in Three Dimensional Scoliotic Deformities

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gradients, as matching can be performed in areas of identical shape, leaving areas of change to be identified [2,3,8]. Unfortunately, the trunk surface lacks prominent features and does not lend itself well to this approach. Taking a full 360 degree view of the torso [10] may improve the surface matching by providing common landmarks and steeper gradients. The surfaces must be fitted manually as it is difficult to reliably and accurately choose landmarks, fit the back surface to an analytic model, or ensure that steep gradients exist from visit to visit. Surface matching is further complicated by the changing shape of the whole trunk through growth and/or weight change, unrelated to the effects due to the scoliotic deformities. 2. Objective The aim of this study was to assess the utility of difference mapping in the clinical followup of children with scoliosis. 3.

Materials and Methods

3.1 Generating the Difference Map Three dimensional trunk surface data sets were captured with a non-contact laser scanner [12]. The subject was positioned in a fixed frame to enhance reproducibility by maintaining predefined scanner-subject separation, and minimizing subject sway and whole body rotation. The subject took a deep breath, and asked to hold it for the 0.6 seconds required to capture the surface map. The surface map comprised up to 40,000 X,Y,Z coordinate points, measured in millimeters, and a TIF image to aid in visualization and image cropping. Difference maps were generated with a program written in MATLAB. The program accepted two ASCII coordinate files, and plotted them as a cloud-of-points in a window that allowed removal of extraneous points. These cropped surfaces were transferred to a surfacefitting window to align the surfaces. The first surface was fixed, while the second surface was manually manipulated to match the first as a best fit. Manipulations included translation in X, Y, and Z to account for differences in positioning, independent scaling in X and Y to account for growth and weight change, and rotation in pitch to account for possible forward leaning. Once the surfaces were matched to the operator's satisfaction, each surface was rendered onto a common triangular grid using standard MATLAB commands. The surfaces were then cropped to the original silhouette to minimize edge effects generated by interpolating the cloud-of-points to a regular grid surface. Areas within the region of interest, not containing surface data (i.e. outside the trunk boundary), were assigned a constant depth value on both surfaces to generate a controlled, common background. Both surfaces were interpolated to a grid of identical dimensions. To generate a difference map, the first surface was directly subtracted from the second on a point-by-point basis. This subtraction produced a third surface with Z values indicating the difference in depth between the original surfaces. Absolute depth differences of greater than 40mm were clipped to either + 40mm, to ensure a fixed depth gradient. A color map ranging from Red (+40mm) to Beige (Omm) to Blue (-40mm) matching the fixed depth gradient, was applied to the surface. A goodness-of-fit score was calculated, based on the average of the absolute value for all trunk surface points, with zero being a perfect match.

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To establish a baseline for the goodness-of-fit score, two subjects each had ten surface images taken at the same session. The subjects moved freely between scans, and repositioned in the frame for each surface image. Each subject's ten topographies had two selected as the first surface against which the other nine were compared. The resulting 36 comparisons (two subjects X two selected references X nine comparisons) were the basis of the repeated measures calculation. The goodness-of-fit scores were only due to positioning and manual errors in fitting the surface images. 3.2 Evaluating the Difference Map Fifty-one consecutive subjects who had two surface topographic images were included. The visits were separated by a mean interval of 6 ± 2 months. The subjects (54 females, 7 males) had a mean age of 14 ± 2 years on their first visit. Of the fifty-one subjects, thirty-four (67%) were diagnosed with AIS and seventeen (33%) with scoliosis of a congential nature or secondary to other conditions. The study group was further divided by treatment modality into twenty-nine surgical subjects (both pre- and post-operative), eleven brace subjects, and eleven subjects undergoing observation only. Two observers judged the changes in surface topography, one observer used only the difference maps and the other observer used all the clinical information available, in the absence of the difference maps. Each subject's color-coded difference map (Figure 1) was generated and analyzed by a blinded observer knowledgeable in scoliosis. This observer was given no information about the subjects, only the 3D surface coordinate points. This observer scored each analysis into one of five categories (Much Better, A Little Better, No Change, A Little Worse, Much Worse). The observer also commented on how the surface topography had changed and recorded the goodness-of-fit score. To analyze the goodness-of-fit scores, A Little Better and A Little Worse were grouped together as slight change, and Much Better and Much Worse were grouped together as severe change. A second independent observer, blinded to the first observer's scorings, analyzed the clinical records for the visits used to generate the difference maps. Examining all available clinical measurements and impressions from the corresponding visits, the second observer scored the subject onto the same five-category scale. This observer also commented on how the individual had changed according to the established clinical measures (Cobb angle, trunk rotation, cosmetic score, scoliometer, and sagittal profile) and physician comments.

Figure 1. Difference map of a subject with moderate worsening of the deformity, showing increased kyphosis and trunk rotation in the thoracic region. Goodness-of-fit = 10.1

D.L Hill et id. /Assessing Changes in Three Dimensional Scoliotic Deformities

18 1

The two observers' category scores and comments were compared and further categorized into one of four levels of agreement. Subjects with identical category scores were considered in Full Agreement. Subjects whose category scores differed by one, but had a consistent deformity assessment were considered in Agreement. Those subjects with category scores differing by one, with inconsistent deformity assessment, were considered in Disagreement. Subjects whose category scores differed by more than one were considered in Full Disagreement. Consistency of the deformity assessment was based on comments on how the surface topography had changed, deemed to be consistent only when the observers agreed upon which specific features had changed (i.e. trunk rotation, flattening of the back, shoulder asymmetry). Agreement scores were analyzed for the entire group, as well as by treatment modality and clinical diagnosis. Goodness of fit scores were assessed using an unpaired two-tailed Student's t-test with a p=0.05 significance level. The effects of treatment and diagnosis were assessed using a chisquared test with Yates correction for discrete data at a p=0.05 significance level. 4.

Results

Judge 1 rated 26 subjects as no change, 21 with slight change, and 4 with severe change. Judge 2 rated 30 subjects as no change, 17 with slight change, and 4 with severe change. Goodness-of-fit scores averaged 5±1 for repeated measures, 7±2 for subjects deemed by judge 1 to have no change, 9±2 for subjects with slight change, and 14+2 for subjects with significant change. These groups were significantly different from each other at p<0.01. Examination of how well the difference map assessment agreed with the conventional assessment showed that 40 of 51 assessments (78%) were in either Full Agreement or Agreement (51% Full Agreement; 27% Agreement). Nine of 51 (18%) assessments were in Disagreement, and only two of 51 (4%) were in Full Disagreement. Figures 2 and 3 show little difference in how subjects were scored relating to either their treatment modality or clinical diagnosis. There was no significant difference for any of the treatment groups (surgery vs. brace, surgery vs. no treatment, brace vs. no treatment). The group with a diagnosis of AIS was not significantly different from the non-AIS group. The number of subjects in each of the groups is small and thus a larger sample size may uncover potential significant differences.

Figure 2. Agreement between difference map and conventional assessment divided by treatment.

Figure 3. Comparison of agreement between difference map and conventional assessment divided by diagnosis.

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5. Discussion The high level of agreement (78%) between the assessment of difference maps compared to established clinical measures indicates that difference maps can reasonably detect and describe changes to the scoliotic trunk. The level of agreement was unrelated to diagnosis or severity. The difference map provides unique insight into surface maps that could help visualize the location and extent of changes in the surface topography. In particular, difference maps were able to portray whole trunk changes "at a glance" and could convey changes not necessarily detected by established measures. The goodness-of-fit score provided a quantitative measure of overall trunk change. However, the goodness-of-fit score was susceptible to the observer's ability to manually align the surfaces without inducing distortion. Scoring of the difference maps into the five categories was also subjective. To make difference mapping clinically relevant, they should be used with knowledge of the subject's diagnosis to establish whether the changes are better or worse (i.e. flattening of the thoracic region may be a positive change for someone with hyperkyphosis but a negative change for a child with AIS). The fitting procedure was helpful as an aid to interpreting surface topography changes, often imparting as much information as the resulting difference map. Specifically, the ability to manipulate the computer generated surfaces to view them from any orientation, allowed for examination of changes in all planes, especially sagittal changes. The fitting procedure of scaling in height and width made observations about growth of the whole trunk possible. Scaling in depth was not used, as depth changes were of primary interest and the interpretation of them was integral to the assessment of changes due to the scoliois. These reasons, combined with the lack of reproducible landmarks, made manual surface fitting preferable over automated computer surface matching algorithms. Automated fitting algorithms, although more computationally intensive, would reduce user bias and error and thus are preferable. Because assessment of surface topography is part of our clinic assessment, generating surface difference maps take only a couple minutes of additional time. This visualization technique provides an educational tool for clinicians, subjects, and families to understand changes in the surface deformity due to natural history or effects of treatment. References 1. 2. 3. 4.

5. 6. 7.

V. J. Raso et al., Trunk distortion in adolescent idiopathic scoliosis, JPO 3 (1998) 222-226. G. E.Karras, On the orientation of digital elevation models in biostereometrics Surface Topography and Spinal Deformity, In: A. Albert!, B. Drerup, E. Hierholzer (eds), Fisher Verlag, Stuttgart, 1992, 162-165. G. E. Karras and E. Petsa, On detection of deformation in reconstructed body models, International Symposium on 3-D Scoliotic Deformities, J. Dansereau, ed., Fisher Verlag, Stuttgart, 1992,370-375. W. Frobin et al.. Shape Analysis of Surfaces: Extraction of Shape from Coordinate Data, In: B. Drerup, W. Frobin. E. Hierholzer (eds.), Moire Fringe Topography and Spinal Deformity ISBN 0-89574-178-4. Gustav Fisher Verlag, New York ,1983, 71-82. M. W. Belin et al., PAR Comeal Topography System (PAR CTS): The Clinical Application of Close-Range Photogrammetry, Optometry & Vision Science 11 (1995) 828-836. R. G. Chadwick et al., Development of a novel system for assessing tooth and restoration wear Journal of Dentistry 1(1997) 41-47. R. G. Chadwick and H. L. Mitchell, Presentation of quantitative tooth wear data to clinicians, Quintessence International W (1999) 393-398.

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8. 9. 10.

1 83

H. L. Mitchell and R. G. Chadwick, Mathematical shape matching as a tool in tooth wear assessment development and conduct, Journal of Oral Rehabilitation 25 (1998) 921-928. J. L. Yaremko, Estimation of Scoliosis Severity from the Torso Surface by Neural Networks, PhD thesis 2001. D. L. Hill et al., Evaluation of a laser scanner for surface topography, In: A. Peuchot (ed.) Research Into Spinal Deformities 3 Series Studies in Health Technology and Informatics, IOS Press, Oxford, In Press

Th.H. GYmn a2

Three-dimensional shape analysis of the scoliotic spine using MR tomography and rasterstereography Eberhard Hierholzer1, Lars Hackenberg2 1

2

Institutfur Experimentelle Biomechanik Klinik undPoliklinikfur Allgemeine Orthopadie Universitat Mtinster, Germany

Abstract. Rasterstereography delivers only indirect information about the threedimensional shape of the spine. Therefore, validation with radiologic methods is necessary, in particular in severe scolioses above 50f. Cobb. Comparison with conventional a.p. radiographs yielded satisfactory results for scolioses up to 50/E Cobb, but only in frontal view, i.e. in two dimensions. A true three-dimensional validation is possible only with MR tomography, however this is difficult due to severe technical limitations. In the present study 26 patients with Cobb angles between 26AL and 116£. were examined both with MR tomography and rasterstereography. Comparing the shape of the spinal midline as measured by the two methods we found that a) the gross 3-d shape of the spinal midline is well reproduced by the rasterstereographic model, b) the lateral rms error is about twice as large as with conventional radiographs and c) that the rms errors increase with increasing Cobb angle. This means that the rasterstereographic model reconstruction must be modified for severe scolioses.

1. Introduction Rasterstereography (VRS) delivers only idirect information on the shape of the scoliotic spine. Starting from data measured solely on the back surface a 3-d model of the spinal midline is constructed [1,2]. Therefore its accurcay is limited, particularly in severe scolioses above 50JE. Aim of the present study was to improve the rasterstereographic model with respect to • accuracy • applicability to severe scolioses > 5QJE Cobb • reduction of outliers and artefacts Our approach consists in comparing the rasterstereographic model curves with true 3-d data from MR tomograms. 2. Materials and Methods 26 patients with idiopathic scoliosis (Cobb angles 26&-1 \6fiL, mean 61JE; age 13-36 years; 23 females, 2 males) were examined. From each patient one MR tomogram and three rasterstereographs were taken within about one hour. Both recordings were taken in prone-lying posture, because MR scans in standing are currently not possible.

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185

For short exposure time special parameter settings for the MR scanner (Siemens Magnetom) were used. In addition, it was necessary to take two interlaced scans, each consisting of 20 slices with 40 mm pitch. Because the MR scanner is generally not intended for recordings in prone lying, a special coil was used to improve imaging of the spine. Nevertheless the image quality was relatively poor and the field was limited to 400 mm. The exposure time was 16 seconds. For rasterstereography a special support similar to that of the MR scanner was built in order to obtain a posture as similar as possible to that in the MR scanner. Moreover, three rasterstereographs were taken, and the patient was asked to walk around between the recordings. Because prone-lying posture is far less reproducible than standing, the best-fitting rasterstereograph was used for comparison with the MR scan. The rasterstereographs were evaluated according to the standard method [2]. Automatic processing of the MR images was not possible due to the limited image quality. Therefore, the comparison was made by interactive visual fitting of the rasterstereographic transverse profiles to the surface contours in the MR slices (Fig. 1).

Fig. 1: Fitting of rasterstereographic profile to MR scan and reconstruction of spinal midline In Fig. 1 the symmetry point is marked by x. The sequence of symmetry points is called the symmetry line which is the rasterstereographic model of the line of spinous processes. The angle of the surface normal at the symmetry point is taken as an estimate for vertebral rotation. From this we obtain the rasterstereographic model of the spinal midline (x) which in turn is taken as an estimate for the vertebral body centre.

E Hierhol-er and L. Hackenberg / Three-dimensional Shape Anal\sis

Fig. 2: MeasureiTient of vertebral body centre and sagittal axis (rotation) For the purpose of comparison the true centre and the sagittal axis of the vertebral body must be determined in each MR slice. This was likewise done by interactive visual fitting (Fig. 2>

For an accurate comparison the rasterstereograph and the MR scan must also be matched in longitudinal direction. This was performed by using a water-filled triangular calibrator which was located 100 mm below the vertebra (Fig. 3). Thus the vertebra prominens can be used as a common reference point.

3. Results and Discussion Fig. 4 shows an example of the spine curves for a 76j4E scoliosis. The solid curves show the MR measurements, the dotted curves represent the rasterstereographic (VSR) model. This is a

187

E. Hierholzer and L. Hackenberg / Three-dimensional Shape Analysis

typical example in that the rms deviations are similar to the average values of all 26 patients. Generally the rasterstereographic curves are in qualitative agreement with the MR curves with respect to shape and location of the apices. However, as shown in Table 1 the average deviations are about twice as large as in earlier studies with digitised radiographs [2,3].

Table 1: Comparison of MR scans and rasterstereographs: Average rms curve deviations Note: Comparison of sagittal curves is not possible with standard a.p. X rays.

method of comparison =>

MR <=> VRS (this study)

Xray^VRS(ref.[3])

26° -116°

<52°

Cobb angle number of patients lateral error ax sagittal error oz axial error ap

26

114

8.8mm 5.0mm 6.0°

4.0mm

2.9°

sagittal error

CTZ = 4.8 mm -^

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lateral error ax = 9.5 mm

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Lateral Projection (mm)

100

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Fig. 4: Comparison of MR (—) and VRS ( • • • ) spine curves (76° scoliosis) The larger errors must be attributed to several factors: • • • •

postural changes between MR tomography and rasterstereography inaccuracies of the MR scans subjective errors in the data analysis (visual fit) larger errors of the rasterstereographic model in severe scolioses

20

188

E. Hierhol-er and L. Hackenhert; / Three-dimensional Shape Anal\sis

The first three factors affect all cases including scolioses below 50 °. However, there is a significant correlation of the errors with the Cobb angle. This holds for the lateral excursion as well as for the vertebral rotation as shown in Fig. 5.

lateral error MR-VRS

ox

rotation error MR-VRS

N = 26 r = 0.70 p = 0.78E-04

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Cobb angle

(a)

(b)

Fig. 5: Correlation of Cobb angle with error of lateral deviation (a) and axial rotation (b) rotation amplitude VRS

lateral amplitude VRS

N= 26 r = 0.79 p= 0.18E-05

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Fig. 6: Correlation of MR and VRS curve amplitudes of lateral deviation (a) and axial rotation (b) (dotted line = expected amplitude) An interesting result is obtained when the curve amplitudes (generally the lateral excursion and axial rotation at the apices) of the MR and VRS curves are compared. We find that

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\ 89

the amplitudes are underestimated by rasterstereography: The lateral VRS amplitude is only 56% and the axial rotation amplitude is only 61% of the respective MR amplitudes.

4. Conclusion Rasterstereography (VRS) yields qualitatively correct spine curves with respect to overall shape, location of apices and axial rotation even for scolioses up to 116°. However, in the case of severe scolioses systematic errors are observed which are correlated to the magnitude of the Cobb angle. Therefore, the existing VRS model for the construction of spinal curves must be modified for Cobb angles above 50 °. The observed errors must be attributed partially to the difficulties of the MR measurement in prone-lying posture. A more reliable examination would be possible if MR systems for standing posture would be available. References 1. 2. 3.

A.R. Turner-Smith, J.D. Harris, G.R. Houghton, R.I. Jefferson, A method for analysis of back shape in scoliosis. J. Biomech. 1988; 21:497-51 B. Drerup, E. Hierholzer, Back shape measurement using video rasterstereography and three-dimensional reconstruction of spinal shape. Clin. Biomech. 1994; 9,28-36 B. Drerup, E. Hierholzer, Assessment of scoliotic deformity from back shape asymmetry using an improved mathematical model. Clin. Biomech. 1996; 11, 376-383

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The effect of posture on Quantec measurements Macdonald A.M.. Griffiths C.J., MacArdle F.J., Gibson M.J. Regional Medical Physics and Orthopaedic Departments, Freeman Hospital, Ne\vcastle-upon-Tyne, NE7 ZDN UK

Abstra-t. The effect of moving the patient's centre of gravity from one extreme to the other, where the weight is entirely supported on the left or right foot at either extreme, was investigated in 33 patients attending for surface topography measurements with the Quantec Spinal Measurement System. Average changes of about 20 were seen in the measured curvature of the lower spine line and pelvic tilt, but there was considerable variation between individual patients. When such extremes of stance were included, the reproducibility of measurements of the curvature of the lower spine, pelvic tilt and vertical alignment was poorer, but not to the extent that a significant improvement in reproducibility would be expected if the patient's centre of gravity was closely controlled with, for example, a force platform.

1. Introduction Surface topography has been suggested as a rapid, non-invasive method of monitoring the progress of a spinal deformity. In Newcastle, we have a Quantec Spinal Measurement System, which uses rasterstereography to measure the back shape. The line of the spine down the back is marked by the operator by palpating spinous processes, starting from the vertebra prominens and attaching a series of markers at intervals down the spine. The operator also marks the dimples of Venus, assumed to locate the posterior superior iliac spines. These markers are identified on the computer screen during the analysis phase and a three-dimensional "spine line" is constructed by the software. Measurements of the curvature of this line in the coronal and sagittal projections are calculated by the computer, as are the angles of pelvic tilt and vertical alignment. Pelvic tilt is the angle between the horizontal and the line joining the dimples of Venus. Vertical alignment is the angle between the vertical and the line joining the vertebra prominens to the intersection of the spine line with the line between the dimples of Venus. We record six measurements in total. Pelvic tilt, vertical alignment, two curves (if present) in the coronal projection of the spine line, which we label "upper" and "lower" according to position, and the thoracic and lumbar curves in the sagittal projection. An earlier study [1] investigated the repeatability of these measurements. This showed that there were two components to the observed variability of the measurements. One is the "within-visit" variability, which can be reduced by averaging measurements from two or more images on each occasion. We take three images in Newcastle. The other component is a "between-visit" effect, which may be partly due to inconsistencies in the placement of markers from one visit to the next, but differences of posture may also be a significant contributor. The location of the patient's feet in the Quantec system is set by a wooden positioning block on the

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floor and we provide handles, at roughly the height of the upper thigh, to help align the upper torso. Although no significant improvement was shown [1] by the use of these handles, we continue to adopt this procedure since it allows the lateral trunk profiles to be clearly seen. The purpose ofthe current study was to test the hypothesis that significant measurement changes might result if the patient shifted their centre of gravity from one foot to the other while their posture was otherwise restrained by the foot block and handles. If this were the case, then we might flirther reduce the variability of our measurements by providing a force platform for the patient to stand on, with suitable feedback to allow the patient to balance their weight on both feet, or to correct for differences in the location of the centre of gravity between one visit and another.

2. Methods Thirty-three patients who attended for routine Quantec measurements were asked if they would volunteer for this study. For these patients, an additional two images were obtained. For one image, the patient was asked to stand with their weight supported on one foot with the other foot resting on the floor. For the other image, the patient's weight was supported by the other foot. No other instructions were given as to how the patient should stand, except that the handles and foot-positioning block must be used. The additional images were processed and measured in the same way as the three images that are normally taken. For the sake of clarity, we refer to the three images taken with the patient standing according to our usual protocol as those from "normal" stance, and the two additional images as (left or right) "extreme" stance. Measurements from the two extremes of stance were plotted against the mean value of the three normal measurements, as shown in Figure 1 for the example of the lower curve. To establish whether or not there was a significant difference between the left and right measurements, a mean difference between the left (or right) measurement and the average of the normal measurements was calculated for the 33 patients.

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Mean curvaturefor notmal stance (°) Figure 1. Plot ofthe lower curve measurements from the right (circles) and left (crosses) extremes of stance against the measurement from the normal stance. The line ofidentity is shown.

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To investigate whether the variability of the measurements is significantly increased by allowing such extremes of stance, we selected one ofthe three normal images and, with the left and right extreme images, calculated the standard deviation ofthe variability ofthe three images (left, right and "normal"). This was done using standard analysis of variance techniques to remove the patient effect - the fact that different patients have different values. Although more elaborate statistical methods could have been used, it was felt that the above simple approach was adequate for our purposes. 3. Results Figure 1 shows, in the case of the lower curve, how the measurements from the left and right extremes of stance compare to the measurements from the normal stance. In some cases, the left extreme measurement is larger than the right, and in others, the reverse is true. In some cases, the measurement from both extremes is larger or smaller than the normal measurement. A similar pattern is seen for the upper curve, the sagittal curves, pelvic tilt and vertical alignment. On average, however, measurements from the left extreme (the crosses) in Figure 1 seem to be around or above the line, whereas those from the right extreme tend to be around or below the line. This is seen more clearly in Figure 2 where the mean differences between the extreme and normal measurements are shown for all Quantec measurements. Only in the case of the lower curve and the pelvic tilt are the measurements from the left and right extremes significantly different at the 5% level. Although on average the pelvic tilt was seen to decrease (pelvis tilts down to the right) when a patient stood on the left foot and increase when standing on the right, in a number of patients the change was the other way round. However, there was no correlation between the direction and angle of pelvic tilt and the changes seen in the other five Quantec measurements.

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A.M. Mucdonuld et al. /The Effect of Posture on Quantec Measurements

Table 1. Standard deviations about the mean for each ofthe six Quantec measurements allowing for an extreme change in stance from one side to the other (top row). For comparison, the standard deviations expected for three normal images as predicted from the earlier repeatability study (middle row) and as actually calculated from the three "normal" images (bottom row). Only the standard deviations marked with an asterisk have p < 0.05 ofbeing due to chance.

Standard deviations ... Extreme change of stance:

Upper curve

Lower curve

Thoracic curve

Lumbar curve

Vertical alignment

Pelvic tilt

2.8°

2.8" (•)

3.6"

2.5°

1.5" (*)

2.6«(»)

Expected:

2.4°

1.9°

3.1°

3.1°

0.98°

1.0°

Calculated ("normal"):

2.4°

1.9°

3.3"

22°

0.62°

1.1°

The results for the thoracic curve are interesting. On average, the thoracic curve increased when the patient stood with their weight on either the left or the right foot, as compared to standing in the normal position. This possibly indicates a more relaxed and slouched posture when standing on one foot. Table 1 lists the standard deviation about the mean of the measurements from the two extreme images and one normal image for each Quantec measurement. These were compared with the standard deviations that would be expected for our normal practice using the F-test (the variance ratio, where variance is the square of the standard deviation). In the case of the upper curve and the two sagittal curves, the difference in the standard deviations is not significantly greater than would be expected by chance. The standard deviations of the lower curve, vertical alignment and pelvic tilt were significantly greater. The difference, however, is small.

4. Conclusions On average, there appears to some change in the measurements of the lower curve, the thoracic curve and pelvic tilt when a patient changes posture from all weight on one foot through evenly distributed, to all weight on the other foot. However, when we look at the variability of measurements with such an extreme change of stance the increase, compared to the variability expected in normal practice, is small in all cases except pelvic tilt. Since we believe that the patient's centre of gravity is fairly close to central in our normal practice, there is little evidence that further control would significantly reduce measurement variation, except possibly in the case of pelvic tilt. References 1.

C. J. Griffiths, J. E. Fitzgerald, R. J. Tweedie, M. Gibson and M. A. Leonard, Accuracy and Repeatability of Spinal Asymmetry Measurements using Surface Topography with and without Upper Body Fixation. In: 3. A. Sevastik and K. M. Diab (eds.), Research into Spinal Deformities 1. IOS Press, Amsterdam, 1997, pp.301304.

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Tli.H. Gri\-u*<Ed. Research into Spinal Ih'tfirinitic\ ~. 10S P'c.vs. 2ni>:

Local Energy as a Measure of Back Symmetry in Scoliosis N. G. Durdle(1), T. Soonawalla01, V. J. Raso(2), D. L. Hill (2) (l>

Dept. Of Electrical and Computer Engineering, University of Alberta (2) Glenrose Rehabilitation Site, Edmonton Capital Health Authority

Abstract: The Cobb angle has been the most commonly used method in measuring the severity of scoliosis and its progression. However, in recent years a number of researchers have chosen to monitor scoliosis by examining the severity of the surface deformity resulting from the scoliosis. Each of these approaches has been limited by errors introduced in manual location of landmarks. Scoliosis results in an asymmetry of the back. It would be very desirable to have a computer-based method of measuring this asymmetry. This paper investigates the use of wavelets and the concept of local energy to measure asymmetry associated with scoliosis. The local energy model uses wavelet theory to obtain information about shading and boundaries of objects in an image. Edges and sharp discontinuities are areas of high local energy in an image. Features such as scapular prominence, shoulder edges, waist creases and other anomalies that contribute to the scoliotic back asymmetry have high local energy. A preliminary study was completed to determine if this approach was applicable to measurement of back asymmetry. Two-dimensional local energy images were created from photographs of the backs of patients with scoliosis. The local energy was integrated across each image and a left-to right line of symmetry was calculated. This line of symmetry was then correlated with the scoliotic score developed by our group. This technique shows promise of providing an automatic method of measuring scoliosis progression.

1. Introduction The Cobb angle has been the most commonly used method in measuring severity scoliosis and its progression. However, what is of greatest concern to the scoliosis patients and their parents is not the spinal deformity itself, but the resulting deformity of the back surface. Consequently, a number of researchers [1,2] have chosen to monitor scoliosis by examining the severity of the surface deformity resulting from the scoliosis. Each of these approaches has been limited by errors introduced in manual location of landmarks. Scoliosis results in an asymmetry of the back. It would be very desirable to have a computer-based method of measuring this asymmetry. This paper describes a preliminary study that uses a photograph of the back of a scoliosis patient to measure the trunk deformity. It uses a local energy algorithm to find edges and areas of greatest change in the image. It then examines the location of local energy with respect to the center of the spine to measure the asymmetry of the back. 2. Objective The objective of this work is to develop an objective computer-based approach to measuring the back asymmetry associated with scoliosis. A local energy algorithm is used to

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produce information about back curvature and edges. This information is assessed to define a measure of left-to-right asymmetry. 3. Background The concept of local energy or phase congruency is based on physiological evidence [3] suggesting that the human visual system responds strongly to points in an image where phase information is highly ordered. As such the local energy model searches for patterns of order in the phase component of the Fourier transform of the image. It was found by Venkatesh and Owens [4] that peaks in phase congruency correspond to peaks in a popular calculation used in biological vision models, namely the local energy E(x): E(x) = J(F2(x) + H*(x)) where F(x) is the one dimensional luminance profile and H(x) is the Hilbert transform of F(x). The preferred method of calculating local energy is via the wavelet transform [5]. This method uses a bank of filters created from rescalings of one type of wave shape, to analyze the signal. Each scaling is designed to 'pick out' particular frequencies of the signal being analyzed. Morlet wavelets are used for this purpose. They are based on complex Gabor functions: cosine waves (even) and sine waves (odd), each modulated by a gaussian as seen in Figure 1. Sets of real and imaginary (Mfeven and Mf°dd) wavelet pairs (each tuned to a particular frequency) are combined over a range of frequencies Freq, forming the filter bank. Each pair acts separately on the image (summing over the frequency range to produce the separate components of local energy, F(x) and H(x), where I(x) denotes the image): F(x)= £/(x)<8>M7"(x) f=Freq

//(*) = £/(*)<8>A/;*(x) f=Freq

This model postulates that features are perceived in an image where the Fourier components are maximally in phase. A wide range of feature types give rise to points of high phase congruency. These include step edges, line and roof edges and Mach bands. Image features (points of high information content in an image), which remain constant over a wide range of viewing conditions, allow for image processing over a wide range of images. These image features usually occur as the high frequency components in an image. ,Odd Wavelet Even Wavelet

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In digital image processing, it is imperative to find invariant quantities i.e. quantities that do not change with orientation, spatial magnification, brightness or contrast of the image. Hence, it becomes necessary to recognize and characterize features in signals in the frequency domain, as features in this domain are dimensionless as well as being robust to noise, shading and contrast variation. The spatial domain is avoided as quantities in this domain are affected by intensity gradients, contrast levels, etc. It must be emphasized that the phase or frequency domain refers to the local phase of the signal at some position x. The local energy model emphasizes that image features are perceived at points in an image where the Fourier components are maximally in phase. Phase Congruency is a dimensionless quantity that is produced by normalizing the local energy of an image and hence, features in an image also correspond to points of high phase congruency. Venkatesh and Owens [4] prove that the energy is equal to the phase congruency scaled by the sum of the Fourier amplitudes. Hence, the local energy function is directly proportional to the phase congruency function, so, peaks in the local energy will correspond to peaks in the phase congruency. Values of phase congruency may vary form a maximum of 1, indicating a very significant feature, down to 0, indicating no significance. This offers the promise of automated feature detection, as thresholds can be set before an image is seen. The local energy model defines areas in an image with high phase congruency. Ridges, edges and regions having high curvature will give rise to high local energy. If an image contains an object with an axis of symmetry in a particular direction, then the local energy will be equal on both sides of this axis. Consequently, an image of a normal back should be symmetrical with respect to the base of the spine and the local energy on either side of the midline of the back should be equal. However, a scoliotic back because of the deformity will have an axis of symmetry offset set from the middle of the base of the spine. Also, at any position on the back, the location of the point with equal local energy left and right will be a function of the deformity. The average value of the points of equal energy and the standard deviation of these locations will provide a measure of the deformity left-to right. 4. Method The local energy model as implemented by Kovesi [7] was applied to a set of images of patients with mild, moderate and severe scoliosis. The image set of 30 subjects contained information on the Cobb angle as well as the scoliosis score as defined by Raso et al. [1]. As the processing is to be carried out in the frequency domain, the fast Fourier transform of the original image is first calculated. Wavelet filters of five different scales are applied to each image with six different orientations. The sum of the local energies from each wavelet filter and from each orientation are added and normalized. Each line of the two-dimensional local energy plot is integrated and the left-to-right location of the midpoint of local energy is defined. Then, the average and standard deviation of the energy midpoints are defined. Both of these values will relate to asymmetry of the image leftto-right. The procedure was first tested on simple, symmetrical and asymmetrical objects.

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5. Results Figure 5 shows the results of applying the local energy algorithm to the image of a rectangle and to a rectangle with distorted side to model a scoliotic back. Figure 2(a) is the original image. Figure 2(b) is the local energy plot with the white lines showing high local energy at the boundaries of the rectangle. The gray bar down the center is the show the midpoints of the local energy at each level. The results from the distorted rectangle show the gray energy midline to be bent to the left. Figure 3 shows the original image and local energy plot for a patient with severe scoliosis. The degree of brightness in the local energy plot is proportional to local energy, white corresponding to high local energy. The gray line is a plot of local energy midpoints and the dashed line is the left-to-right average local of midpoints. It was found that the midline of the local energy pattern did not correlate well with either the Cobb angle or the scoliosis score for any of the categories, mild, moderate or severe. However, it was found that for the moderate and severe scoliotic cases, the standard deviation of the local energy midline correlated with the scoliosis score but not with the Cobb angle. For mild scoliosis, neither the midline of the local energy pattern or its standard deviation correlated with the Cobb angle or the scoliosis score. An example of the correlation for the ten severe cases is shown in Figure 4.

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6. Discussion This preliminary study indicates that local energy could lead to a computerized method of measuring the deformity associated with scoliosis. However, the limited number of subjects in this study does not permit a conclusion as to effectiveness of this approach. References 1. 2. 3. 4. 5. 6. 7.

V. J. Raso, E. Lou, D. L. Hill, M. K. Mahood, M. J. Moreau, N. G. Durdle, Trunk Distortion in Adolescent Idiopathic Scoliosis, Journal of Pediatric Orthopedics, 18(3), 1998 pp. 222-226. N. Suzuki, K. Inami, T. Ono, K. Kohno, M. A. Asher. Analysis of Posterior Trunk Symmetry Index (POTSI) in Scoliosis, Research into Spinal Deformities 2,1.A.F. Stokes (Ed.), 1OS Press, 1999, pp. 83-84. M. C. Morrone and D. C. Burr. Feature Detection in Human Vision: A phase-dependent Energy Model. Proceedings of the Royal Society of London B, 235, 1988, pp. 221-245. S. Venkatesh and R. A. Owens. An Energy Feature Detection Scheme. IEEE Int. Conf. On Image Processing, Singapore, 1989, pp. 553-557. J. Morlet, G. Avens, E. Fourgeau and D. Giard. Wave Propagation and Sampling Theory - Part II: Sampling Theory and Complex Waves. Geophysics 47(2), 1982, pp. 222-236 M. C. Morrone and R. A. Owens. Feature Detection from Local Energy, Pattern Recognition Letters, 6: 1987, pp. 303-313. P. Kovesi, Image Features From Phase Congruency. Videre: A Journal of Computer Vision Research. MIT Press. Volume 1, Number 3, Summer 1999. http://mitpress.mit.edu/e-journaIsA^idere/OOI/vl3.html

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Monitoring the thoracic sagittal curvature in kyphoseoliosis with surface topography: a trend analysis of 57 patients McArdle F. J., Griffiths C. J., Macdonald A. M., Gibson M. J. Regional Medical Physics and Orthopaedic Departments, Freeman Hospital, Newcastle-uponTyne, NE7 7DN UK

Abstract. Records of Quantec measurements of tlie kypliotic curvature of the back were reviewed for all patients attending the children's orthopaedic clinic who were referred for back shape measurements. Of these, 57 children had five or more preoperative visits allowing trends to be calculated. Linear trends were found in 30 of the patients, with gradients ranging from l.l°/yr to 7.2"l/yr. On average, the scatter of measurements about the trend line, or about the mean value in the other 27 cases, compared well with that expected from repeatability studies but the amount of scatter varied from one patient to another. This may well be due to sampling. Where such measurements are monitored for evidence of change in an individual patient, the possibility of larger than average scatter about any emerging trend should be considered.

1. Introduction We use a Quantec Spinal Measurement System in the children's orthopaedic clinic to make a number of measurements of the back shape of children with kyphoseoliosis. The aim of these measurements is to help distinguish patients whose deformity is static from those in whom it is progressing. An earlier study [1] examined the repeatability of several Quantec measurements and showed that the variance of the measurements has a significant "betweenvisit" component. This means that, in the absence of any change of the underlying deformity, there will be a "systematic" error component superimposed on all measurements made at any one visit, that varies from one visit to the next. This component may be partly due to changes, from time to time, in how the patient stands or stoops and has been recognised as a complicating factor for Cobb angle measurements [2, 3]. From our repeatability study, we calculated 95% confidence limits for the null hypothesis that an observed change in any measurement, from one visit to the next, was due to the variability of the measurement itself and not to a real change. We have used these confidence limits as objective criteria for reporting to the referring surgeon whether a measurement has changed or not. This study reviews our clinical measurements with the Quantec System, which has been in use since 1 994. Our protocol has not changed significantly over that period, so we have no reason to believe that our measurement variability has changed. The study examines our criteria for reporting a change of measurement with the benefit of hindsight. Short-term changes from one visit to another are compared with longer-term trends in the measurements to verify whether the variability about a trend is as expected from our earlier

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repeatability study. The study is limited to the single measurement of the thoracic curvature in the sagittal projection. 2. Methods Patients attending for Quantec Imaging first have the line of the spine marked down the back by a series of small adhesive paper markers. These are located by palpating the spinous processes and placing a marker on the back above one of these processes. Typically, six to eight markers are used. When the images are later analysed, the "spine line" is defined by identifying the location of these markers on the computer with a mouse. The analysis software draws a line through the points identified across the surface of the back. When displayed in the sagittal projection, the software identifies the inflection points in the upper thoracic and thoracolumbar regions where the angle of the spine line to the vertical is maximal. The difference between the angles at these two inflection points is a measure of the thoracic curvature of the back surface. At our centre, we collect and analyse three images of the back. Between each image, the patient is asked to step out of the positioning frame and then to step back in. In the positioning frame, the patient's feet are located on either side of a positioning block on the floor and upper body position is restricted by holding two handles about upper thigh level. The height of the handles is adjusted for the patient to ensure that the patient does not stoop nor raise the shoulders. In addition, before each image is captured, the patient is asked to stand as tall as they can. For this study, we reviewed the records of all patients who have attended for Quantec imaging since 1 994. To examine the variability of the measurements about a trend, we needed to select patients who had been seen on sufficient occasions, prior to spinal fixation surgery, for a trend to be determined. We chose five or more occasions as a compromise between enough data to establish a trend and a sufficient number of patients to analyse. For each patient in the study, we have three measurements of the thoracic sagittal curvature at each of five or more occasions, typically six or twelve months apart. An analysis of variance was performed to establish whether or not there was a statistically significant "betweenvisit" component in the measurements. Where a "between-visit" component was established, a linear regression analysis established whether a statistically significant linear trend existed. If so, the regression line was subtracted from the measurements. If a statistically significant higherorder relationship exists, suggesting a changing trend, this too would be subtracted. When all trends are removed, the remaining differences between the measurements are the inherent variability that we cannot explain or control. This residual variance is the scatter of the measurements about the best-fit line through the data. A histogram was plotted of the residual variance, here expressed as a standard deviation, for all of the patients in the study. 3. Results At the time of this study, 57 patients had been examined by our Quantec system on five or more occasions prior to surgery. The average number of visits for the group was 6.3 with a range from 5 to 11. The patients naturally divided into two groups (Figure 1). In one group, containing 30 patients, there was a significant linear trend. In 20 ofthese patients, the trend was

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increasing (rangel.l°/yr to 7.2 °/yr) and in the other 10 decreasing (range:- 1 .7 ° /yr to -4.7 /yr). In the second group, there was no significant linear trend. The thoracic

1

2

3

4

Years fromfirst visit

1

2

3

Years from first visit

Figure 1. Data from two patients in the study illustrating, on the left, a significant linear trend with marked scatter about the trend line and, on the right, no trend and little scatter about the mean.

curvature remained effectively constant. There was no evidence in either group of significant higher-order trends. The residual variance for patients in the two groups is therefore either the scatter about the linear regression line, or the scatter about the mean value. Residual variances of individual patients, expressed as standard deviations, ranged from 1.5 ° to 6.5 °. The distribution is shown by the histogram in Figure 2. The average value (the square root of the average variance) was 3.8 °. 4. Discussion In some ways, this study is similar to a repeatability study but there are important differences. To study how reproducible measurements are, it is important to arrange repeat visits over a period of time that is short compared with the time scale of likely changes of the underlying deformity. In this way, we ensure that we are trying to measure the same quantity. In this study we have to make assumptions about whether or not the underlying deformity is changing and, if so, how. If we happen to be correct in every case, then by allowing for how the quantity is changing, the residual variation in our measurements will be the same as that obtained from a repeatability study. If there are changes that are not 20 T

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1 2 3 4 5 6 7 Standard deviation ( ° ) about the trend line or mean

Figure 2. Histogram ofthe standard deviation ofthe scatter about the trend line, or the mean where no trend exists, for all 57 patients in the study.

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allowed for, these will be superimposed on the residual variation to give a larger value than we would otherwise get. In this study, the average standard deviation of the residuals was 3.8 °, which is fairly close to the value of 3.4 ° obtained from our repeatability studies. This suggests that we have accounted for all significant changes to the thoracic curvature in this group of patients. Repeatability studies are often limited by the number of patients that can be recruited and by the number of visits that can be arranged for each patient. This is not the case here. In this study, we can determine the variability of individual patients and have plotted their distribution as a histogram. If we assume that, for all patients, the true variance of measuring thoracic curvature is the same, then we should expect that the variance estimated from any set of, say five, visits will be slightly different than the variance estimated from a different set of five visits due to sampling. Alternatively, if all patients have the same true variance, the variance estimate from one patient would be expected to be different from the variance estimate from another. In other words, a variance itself has a variance due to sampling. In this study, we found a range of variances. It is not clear whether or not there are true differences between patients, but the range we see is not very different to what we would expect from sampling. Sampling undoubtedly is a major factor. Whether differences in the variance calculated for one patient study, as compared with another, are due to sampling or an inherent difference in the variances of individuals, the fact remains that different variances will be calculated for different studies. Variance is used to calculate, via its square root (the standard deviation), 95% confidence limits for a change of measurement. Based on our own repeatability study, giving a standard deviation of 3.4 °, the 95% confidence limits for the difference between two measurements are ± 9.4° When a measurement of thoracic curvature changes by more than this, we might report this to the referring surgeon as an increase (or decrease) of thoracic curvature. Since this is a 95% confidence limit, we would expect to be wrong (a Type I error, or false positive) one in 20 times. While this may be true for all reports from Quantec measurements in general, the evidence from this study is that there will be some patients (i.e. those studies with a standard deviation of 6.5°) where almost every second visit will cause a false positive report. 5. Conclusions We must expect the variance of measurements to vary from patient to patient, and possibly also from time to time in the same patient. Consequently, criteria of measurement change based on the average variability of all patients may give high false positive rates in some patients. Caution should be exercised when such criteria are applied to individual cases. With the variance expected for measurements of the thoracic curvature, it is possible to detect trends as small as 1 ° /yr over a series of about six visits.

F.J. McArdle et al. /Monitoring the Thoracic Sagittal Curvature in Kvplioseoliosis

References C. J. Griffiths, J. E. Fitzgerald, R. J. Tweedie, M. Gibson and M. A. Leonard, Accuracy and Repeatability of Spinal Asymmetry Measurements using Surface Topography with and without Upper Body Fixation. In: J. A. Sevastik and K. M. Diab (eds.), Research into Spinal Deformities I . 105 Press, Amsterdam, 1997, pp.301304. C. Zetterberg, T. Hansson, J. Lidstrom, L. Irstam and 0. B. Andersson, Postural and Time-dependent Effects on Body Height and Scoliosis Angle in Adolescent idiopathic Scoliosis, Ada Orthop Scand 54 (1983) 836840. M. Beauchamp, H. Labelle, G. Grimard, C. Stanciu, B. Poitras and J. Dansereau, Diurnal Variation of Cobb Angle Measurement in Adolescent Idiopathic Scoliosis, Spine 18 (1993) 1581-1583.

Tli.H. (invas iLd.i Research inio Spinal Dcfurninu-s 4 IOS Pn w 2"<>2

Use of Functional Tests to Increase the Efficiency of Scoliosis Screening Diagnosis by COMOT Method V.N. Sarnadskiy, N.G. Fomichev, M.V. Mikhailovsky Novosibirsk Research Institute of Traumatology and Orthopaedics (NIITO), Frunze sir. 17, 630091 Novosibirsk, Russia

Abstract. COMOT technique was developed at Novosibirsk Research Institute of Traumatology and Orthopaedics as a pilot study in 1997 was used for screening for spine deformities in schoolchildren in Novosibirsk, Omsk and Moscow. Topographic screening was performed with patient standing in his natural free and easy posture. The criteria for scoliosis detection was an angle of lateral asymmetry (LA), calculated on the basis of topographic data, which was an analogue of Cobb angle. An additional criterion for structural spine deformation was an angle of scoliotic arch apex rotation (R). The analysis of responsiveness and specificity of topographic test (TT) at detection of structural arches of 10 and more degrees (according to Cobb) showed that they depend on the level of taken thresholds.

1.Introduction COMputer Optical Topography (COMOT) technique developed at Novosibirsk Research Institute of Traumatology and Orthopaedics in 1994 as a pilot study was used for school screening for spine deformities in Novosibirsk, Omsk and Moscow in 1997 [1]. Topographic screening was performed with the patient standing in his natural free and easy posture. The experience of organization of mass screening for scoliosis by COMOT has shown, that use of this technique for examination of patients standing in their natural free and easy posture is effective and allows recording and processing images of up to 300-400 patients per day (8 hours). However correct interpretation of topographical results needs the qualified medical personnel, and in some cases it is impossible to make the conclusion based on one image of a patient without his additional clinical survey. It is connected to the accepted rule to examine patients in a natural pose, that is undoubtedly important for an all-round estimation of postural and shape disorders in the spine in three planes. However, expressed disorders of the patient's posture can result in false revealing of scoliotic deformation of the spine (false - positive result) or missing the early stages of structural scoliosis (false - negative result). The most informative topographical sign of structural scoliosis at its initial stage is a local rotational asymmetry in a paraspinal region. This asymmetry is described by the plot of axial rotation of a trunk dorsal surface in the horizontal plane and is a consequence of structural spine rotation with a maximum being in the apex of a curvature arch. The typical reasons of distortions of a surface rotation plot and difficulties in interpretation of the data during examination of patients in their natural pose are: essential rotational deformation of a trunk (more than 5° twist

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of the shoulder girdle relative to pelvis), significant lateral deviation of a trunk axis (more than 10 mm lateral deviation of a spinous process line from a median trunk line), expressed lumbar lordosis (more than 30° pelvic inclination in the sagittal plane), asymmetrically located and/or closely brought together scapulae. The above mentioned reasons cause large percentage of false positive results when only one natural pose is used for screening. To increase the specificity of screening for scoliosis with computer topographic system we developed special standing positions (functional poses) in addition to natural one. 2. Aim

The purpose of the present research is a comparative study of the efficiency of structural scoliosis detection in the suggested functional poses and a conventional natural pose. 3. Materials and Methods COMOT technique has been developed based on a fringe projection method. In comparison with the best-known video-rasterstereography technique, which is applied in such automatic topography systems as JENOPTIC formetric [2], QUANTEC [3], which perform direct measuring of grating line coordinate, COMOT is based on phase-measurement method, that provides evaluation of surface shape in all points of patient image without interpolation. A commercially available automatic topography system, named TODP was created in 1995, and was admitted by Health Ministry of Russia to medical practice. TODP system provides quantitative analysis of back surface shape with evaluation of large number of topographic parameters, including trunk asymmetry, angular orientation in the frontal, sagittal and horizontal planes of a trunk and mutual orientation of its part. For estimation of the scoliotic spine deformation by a location of a spinous processes line on a back and by an angle of surface rotation, an axial line of the spine is calculated and the automatic revealing of scoliotic arches with the evaluation of an apex level and arch ends is performed. Each revealed arch is described by an angle of lateral asymmetry (LA), which is a topographic analogue of Cobb angle. An additional criterion for defining structural spine deformation is an angle of rotation (R) of scoliotic arch apex. This angle characterizes a rotation of paraspinal surface at a level of arch apex relative to the lower and upper ends of the arch. To increase efficiency of topographic screening it is suggested to use special standing positions (functional poses) in addition to a natural one (pose 1). These poses correspond to various degrees of spine flexion-extension in the sagittal plane: • "active pose" - standing in a "quiet" position with the tightened abdomen and the straightened back (pose 2); • pose with maximum flattened lumbar lordosis (pose 3); • pose with increased lumbar lordosis and flattened thoracic kyphosis (pose 4); • pose with maximum moved apart scapulae, increased thoracic kyphosis and flattened lumbar lordosis (pose 5). In Fig. 1 and Fig. 2 the results of the examination of two patients in natural and described above functional poses are given. Fig.l shows a 8.2 -year-old patient with nonstructural left spine curve (T8-T12-L3, 7° of Cobb ), and Fig.2 shows a 7.6-year-old patient with structural left spine curve (T10-L1-L4, 11° of Cobb). Comparison of plots of surface rotation demonstrates considerable difference between nonstructural and structural spine curves.

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In the first case paraspinal asymmetry (surface rotation) is manifested only in pose 2 and comprises about 2°. In structural spine curve the paraspinal asymmetry is detected in all five poses averaging about 3.4°. For this study 231 patients (91 male and 140 female) with a mean age of 11.112.23 years (range 7.1-16.2 years) and with a mean Cobb angle of 6.39 °± 7.98 (range 0 - 30°) from Novosibirsk boarding school No. 133 for scoliotic children were examined. All of them underwent X-ray and TODP examinations within one-month period. The patients were subdivided in four groups (GO-G3, Table 1). Group GO consisted of 96 patients without structural scoliosis and with Cobb angle less than 7°. The rest groups included 135 patients with idiopathic structural scoliosis. Group Gl consisted of 84 patients with a range of Cobb angle from 5° to 10° (first stage of scoliosis according to Russian medical practice), group G2 (36 patients) - from 11 ° to 20° and group G3 (15 patients) - from 21 ° to 30°. Table 1. Description of groups included in the study. Sex Group N Age Main curve localization Cobb angle Side male female Level MeaniSD Mean±SD Lef right T T- L N % N % Range t L 64 32 44 2 0-7° 4.54±2.52 96 10.5 1 ±2.3 52 54.2 44 45.8 10 GO 33 22 5°-10° 8.6511.56 84 10.8812.0 59 51 3 28 33.3 56 66.7 Gl 1 21 17 18 14.7812.3 7 19.4 29 80.6 15 11°-20° 36 10.89+2.1 G2 G3

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4. Results Mean values of LA angle were calculated for each group in natural posture (Pose 1) and four functional poses (Pose 2 - Pose 5), and for each patient in all poses (Table 2). At individual averaging the angle meanings of a main arch of the curvature were summarized

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-

(pose 1)

l . l . l ) - l . S . l ) d igitized TV-frames of a patient

1.2)Active posture

-

(pose 2)

1.1.2)- 1.5.2) topogramm of the back with 5 mm distance

1.3)Flat lumbar lordosis

-

(pose 3)

1.1.3)- 1.5.3) frontal views of a patient's back

1.4)Increased lumbar lordosis

-

(pose 4)

1.1.4)- 1.5.4) plot of surface rotation

1.5)Maximal lateral shift of

-

(pose 5)

the scapulae

1.1.5)- 1.5.5) sagittal views of the spinous processes 1.1.6)- 1.5.6) horizontal views of a patient's back

209

V.N. Sarnadskiy et al. / Use of Functional Tests to Increase Efficiency

2.1.6)

2.2.6)

2.3.6)

2.4.6)

2.5.6)

Fig.2. A 7.6-year-old patient with structural left spine curve (T10-L1-L4, 11° of Cobb). (Numeration in Fig.2 corresponds to that in Fig.l.)

with consideration for a sign denoting the side of an arch convexity ("+" for right side, "-" for left side). It should be noted, that in comparison with natural posture, the averaging of LA according to poses gives essential reduction of SD in all analyzed groups (more than 2 times in GO and about 1.4 times in other groups). Thus, suggested functional poses provide more reliable estimation of structural scoliotic deformities, especially with small curves. Table 2. The LA angle in natural posture (posel) and functional poses Group GO Gl G2 G3

Pose 1 Mean ± SD 4,49 ± 3,55 7,92 ± 2,54 14,4813,12 23,73 ± 4,32

Pose 2 Mean ± SD 3,75 ±3,15 8,73 ± 2,45 14,30 ±2,83 24,04 ± 3,56

Pose 3 Mean ± SD 4,37 ± 2,95 8,05 ± 3,83 14,61 ±4,44 25,76 ±4,98

Pose 4 Mean ± SD 5,01 ± 2,94 7,78 ± 4,04 14,63 ± 5,06 23,52 ± 5,26

Pose 5 Mean ± SD 2,73 ± 3,04 8,28 ± 2,67 13,97 ±3,61 2 1,40 ±3,27

Mean value Mean ± SD 4,07 ±1,66 8,15 ±1,82 14,40 ±2,32 23,69 ± 3,01

To compare topographic screening test (TST) for detection of structural scoliotic curves in only natural pose and in the proposed functional poses we studied the possibility of an automatic classification of patients between group GO and gl with different level of thresholds for R (range 1.5 - 3.0) and one level of threshold for LA = 5°. The TST result was "Positive", if LA>5°, R> threshold and R had the same sign as LA. In other cases TST result was "Negative". Pose averaged LA and R angles are compared with the threshold for TST in functional poses. Only those arches location of which corresponded to that in a natural pose or differed in one or two vertebrae were included for averaging. Results of this comparison are presented in Tables 3 and 4. The analysis of sensitivity, specificity and positive predictive value of TST in functional poses demonstrated essential growth of the diagnostic efficiency, which is reflected in Table 4. Thus, the TST in functional poses is significantly better than the TST only in natural pose.

V..V. S(irnt«lski\' ct al. / Vsc of Functional Tests to Increase

Efficient^

Table 3. The findings for topographic screening test with group GO and G1 Result

Positive Negative Totals

TST only in natural posture Meanings of used thresholds for rotation R>1.5° R>2.0° R>2.5° R>3.0° GO Gl GO Gl GO Gl GO Gl 55 81 30 80 23 77 15 73 41 7 3 66 4 73 81 11 84 96 84 96 84 96 84 96

TST with functional poses Meanings of used thresholds for rotation R>2.5° R>1.5° R>2.0° R>3.0° GO Gl GO Gl GO Gl GO Gl 13 82 7 81 21 83 3 77 83 2 89 3 93 7 75 1 84 84 96 84 96 84 96 96

Table 4. Sensitivity, specificity and positive predictive value for topographic screening test TST only in natural posture | Meanings of used thresholds for rotation Sensitivity

Specificity PPV

TST with functional poses Meanings of used thresholds for rotation

R>1.5°

R>2.0°

R>2.5°

R>3.0°

R>1.5°

R>2.0°

R>2.5°

R>3.0°

96% 43% 60%

95% 69% 73%

92% 76% 77%

87% 84% 83%

99% 78% 80%

98% 86% 86%

96% 93% 92%

92% 97% 96%

5. Conclusion The performed studies demonstrated that use of functional poses allows solving the problem of high percentage of false-positive results of TST. It should be noted that due to complete automation of topographic data processing by COMOT method labour consumption of screening does not increase essentially. References Fomichev N.G., Kharinov V.N., Sarnadskiy V.N., Sadovoy M.A., Malakhov O.A. School spinal deformity screening by computer optical topography. Research into Spinal Deformities 2,1.A.F. Stokes Ed.), IOS Press, 1999, p.241. Drerup B., Hierholzer E. Back shape measurement using video rasterstereography and three-dimensional reconstruction of spinal shape, Clin. Biomech. 1994, Vol.9, pp. 28-36. Wojcik A.S., Phillips G.F., Mehta M.H. Recording of the back surface and spinal shape by the Quantec imaging system- a new technique the scoliosis clinic.J.Bone Joint Surg.,1994,V76-B(Supp. I), pp. 10-11.

777.fi. Grivas(E(l.) Research into Spinal Deformities 4 IOS Press. 2002

Cotrel-Dubousset instrumentation (GDI) in the treatment of congenital spinal deformities. Computer topography evalution Mikhailovsky M.V., Sarnadsky V.N., Khanaev A.L. Research Institute ofTraumatology and Orthopaedics, Department of Spinal Surgery for Children and Adolescents, 630091,Frunze str. 17, Novosibirsk, RUSSIA Abstract. Aim of the study. GDI and other types of segmental instrumentation are wide used in surgical treatment of congenital spinal deformities. At the same time we didn't find in orthopaedic literature any data concerning 3-D evaluation of the results of such procedures. The aim of this study is the assessment of 3-D effect of GDI using of computer optical topography.

1. Introduction Cotrel-Dubousset instrumentation (GDI), developed in 1983, is widely applied in the surgery of congenital deformations of the spine. Its high efficiency is convincingly proved by numerous researches (Dubousset,1985; Bradford, 1985; Winter,1988; Lonstein, 1991). In the last years methods of three-dimensional estimation of dorsal trunk surfaces of the patient for comparison of intervention results are used. For this purpose ISIS optoelectronic topographical system (Turner-Smith, 1993) based on computer and television techniques, and such systems as Formetic (Drerup, 1994) and Quantec (Wojcik, 1994) based on rasterostereography are most widely applied. In 1994 at Novosibirsk Research Institute of Traumatology and Orthopaedics a COMputer Optical Topography technique was developed based on a fringe projection method. It surpasses all the above mentioned systems in many parameters: rate of processing (10 seconds instead of 1 - 2 minutes), the spatial resolution of a restored surface, a level of automation of processing. 2. Aim

To estimate short term changes in the shape of a trunk dorsal surface and the position of a patient's body in three-dimensional space by computer-optical topography after surgical correction of congenital deformation with Cotrel-Dubousset instrumentation. 3. Material and methods The results of the surgery of patients with congenital scoliosis treated with various modifications of GDI are studied. The data of standard radiographic and clinical examinations,

212

M. V. Mikhoilovsk\ et al. / Cotrel-Dtihousset Instrumentation tCDIl

and computer optical topography estimations of shape of a trunk dorsal surface before and after surgery were used for analysis of outcomes in 27 operated patients with congenital scoliosis (22 girls and 5 boys) at the age of 8 - 36 years (mean age 16,4 years). In 78 % of cases the deformations were caused by multiple anomalies of vertebral development. Results of complex examination before and after surgery were analyzed. Standing spondilograms in two projections were performed before surgery and in a week after it. The sizes of scoliotic arches, kyphosis and lordosis were determined according to Cobb. Rotation of the apex vertebra was not studied as the application of GDI for congenital spine deformations does not assume "derotation manoeuvre", and consequently, changes in this parameter (Dubousset, 1991). The computer optical topography was performed at standard follow-up terms and contained 90 parameters of shapes in two basic lateral and horizontal-sagittal planes, out of which only 11 parameters correlating with clinical and radiological data were selected for analysis. These parameters are the following: Frontal plane: Pelvic inclination -from 3,9° to 2,98° (-23,6%) Shoulder tilt -from 4,3° to 2,7° (-36,6%) Frontal balance-from 19,6MM to 18,9MM(-3,9%) Sagittal plane: Thoracolumbar inclination -from 30,53° to 19,62°(-35,7%) Thoracic kyphosis height -from 35,5 MM to 29,9 MM (-15,6%) Lumbar lordosis height -from 34,3 MM to 26,9 MM (-21,5%) Pelvic inclination -from 22,5° to 20,9°(-7,5%) Sagittal balance -from 4,04° to 3,34° (-J7,3%) Horizontal plane: Primary curves apex rotation -from 36,7° to 26,3° (-28,4%) Volumetric asymmetry of the thorax —from 23,9MU to 18,6MM (-22,1%) Relative twisting of shoulder and pelvic girdles -from 6,6° to 4,6° (-30,5%) 4. Results Pre- and postoperative values of radiographic and topographical parameters in both groups of patients are presented in Tables 1 and 2. Sizes of scoliotic arches, kyphosis and lordosis and deformations determined on x-ray pictures correspond to the numerous results published in the orthopaedic literature and require discussion only in a context of their correlation with the computer topographical data. The initial average size of the spine scoliotic deformity was 80,3°, after operation it decreased up to 63,6°.The size of a kyphotic component initially comprised 84,0°,after operation-69,3°(Table 1). The radiological data were compared with the data received during computer - topographical examination (Table T).

213

M. V. Mikhailovsky et al. / Cotrel-Dubousset Instrumentation (CDI)

Table 1. X-ray parameters. Parameter No 1. Primary curve (°) 2. Secondary curve (°) 4. Kyphosis (°) 3. Lordosis (°)

Before 80,3 61,8 84,0 49,7

After 63,6 52,0 69,3 43,6

Alter 14,13

9,2 6,5 12,3

% -20,8 -15,9 -17,4 -12,6

Table 2. Topographical parameters before and after operation. No

1 Parameter

Before

After

Alter

%

Frontal plane

1

Pelvic tilt (°)

3,92

2,98

2,88

-23,6

2

Shoulder tilt (°)

4,27

2,7

11,6

-36,6

3.

Frontal balance (mm)

18,9

8,73

-3,9

8,73 8,04

19,62 29,9 26,9 20,85 3,34

9,7 2,8

-35,7 -15,6 -21,5 -7,5 -17,3

9. 10

19,6 Sagittal plane Thoraco-lumbar region's inclination (°) 30.53 Thoracic kyphosis height (mm) 35,5 Lumbar lordosis height (mm) 34,28 Pelvic sagittal inclination (°) 22,55 4,04 Sagittal balance (mm) Horizontal plane Primary curves apex rotation (°) 36,68 Volumetric asymmetry of the thorax (mm) 23,98

26,26 18,63

9,04 4,78

-28,4 -22,1

11

Horizontal balance (°)

4,56

3,5

-30,5

4. 5. 6. 7. 8.

6,56

6,79

Computer optical topography of a patient's trunk in the frontal plane has shown, that in the nearest postoperative period GDI substantially reduces an inclination of the shoulder girdle (parameter 2), essentially reduces an inclination of the pelvis (parameter 1) and to a lesser degree influences the frontal balance (parameter 3). Correction with polysegmental instrumentation normalizes the position of the scapulae and corrects a shoulder tilt. Reduction of the shoulder girdle inclination (parameter 2) is probably related to the influence of CDI on the rigid thoracic arch. Parameters 1 and 3 are not changed much, probably due to initially small misbalance of the trunk at the expense of compensating lumbar counter-curve. In the sagittal planes distinct positive dynamics of correction of the thoracolumbar curve (parameter 4) is revealed, which is in its turn related to height reduction of the thoracic kyphosis (parameter 6) and reduction of lumbar lordosis (parameter 7). The correction of pelvic tilt is insignificant (parameter 5). Sagittal parameters strictly correspond to the magnitude of kyphosis correction and characterize restoration of sagittal balance of the trunk (parameter 8). Apex rotation of a main arch and volumetric asymmetry of the rib cage (parameters 9 and 10) characterize derotation effect of CDI and changes in parameters in the horizontal plane. Although derotation manoeuvre is not used for congenital deformations, we managed to achieve the effect of passive derotation. Perhaps, this effect of CDI application is caused by the direct influence of hooks installed in intermediate vertebrae on the apex of deformation. Changes in

M. V. Mikhailovsk\ et al. / Cotrel-Dnhoussei Instrumentation (CDI}

parameters 10 and 11 are explained by the indirect action of corrective efforts on the shape of the rib cage via the main arch (Fig. 1).

Fig.l. Back shape of patient before and after surgery with CDI, left panel - before, right panel - after surgery.

5. Conclusions The computer optical topography has allowed to estimate inherent changes in the trunk position of a patient in three-dimensional space and to receive an additional parameter, which cannot be received by radiography - a change of the shoulder girdle position relative to the pelvis in the horizontal plane (parameter 11). This parameter evidently gives an opportunity of threedimensional correction of congenital deformations of the spine with circular fusion (360° fusion) and CDI installation. This instrumentation provides normalization of the trunk balance and a significant cosmetic effect. Computer optical topography confirms significant improvement of a large number of parameters in surgical correction of congenital spinal deformities. The course of the adaptation of patients to new conditions of static and dynamics resulted from the correction of the spine will prove within time and further researches.

M. V. Mikhailovsk\ et at. / Cotret-Dubousset Instrumentation (CD!)

215

References 1. 2.

3. 4. 5.

6.

7.

8. 9. 10.

Cotrel Y, Dubousset J, Guillaumat M: New universal instrumentation in spinal surgery. Clin Orthop, 1988, N 227, pp 10-23 Csongradi JJ, Bleck EE: Moire toporgaphy: use in scoliosis observation. In Moire fringe topography and spinal deformity. Edited by Drerup B., Frobin W., Hierholzer E. Stuttgart, New Jork, Gustav Fischer Veriag. 1983, pp 141-148 Drerup B, Hierholzer E: Back shape measurement using video raster-stereography and threedimensional reconstruction of spinal shape. Clin Biomech, 1994, v.9,Nl,pp 28-36 Dubousset J: Congenital kyphosis. In. Bradford DS, Hensinger RM (eds): Pediatric Spine. New York. The Theieme- Stratton, 1985. Edgar MA, Bettany JA, Ransford AO, Harrison DJ: ISIS assessment of costoplasty: Preliminary results. Surface Topography and Spinal Deformity. Edited by-Albert! A, Drerup B, Hierholzer E. Gustav Fischer Veriag, Stuttgart, Jena, New Jork, 1992, pp 83-88 Lecire C, Skalli W, Zeiler R, Dubousset J, Lavaste F: Three-dimensional per-operative opto-electronic analysis of Cotrel-Dubousset surgery. Research into Spinal Deformities 2. Edited by I.A.F.Stokes, 1998, pp 118-121 Mikhailovsky M, Sarnadsky V, Novikov V: Three dimensional correction with CD instrumentation and pure Harrington distraction in the treatment of idiopathic scoliosis. GICD-s 3rd Eastern European Forum. St. Petersburg 1999. Takasaki H: Moire Topography. AppI Opt, 1970, v.9, N 6, pp 1467-1472 Turner-Smith AR: A television/computer three-dimensional surface shape measurement system. J.Biomechanics, 1988, v.21, pp 515-529 Willner S: Spinal pantograph - a non-invasive anthropometric device for describing postures and asymmetries of the trunk. J Pediatr Orthop, 1983, v.3, pp 245-249

216

Th.R. ('-mas tEd i Research into Spinal Deformities 4 !(>S /••;•<• vs. 2df>2

Three-dimensional correction with CD Instrumentation and Harrington rod in the treatment of idiopathic scoliosis M.V. Mikhailovsky MD V.V. Novikov, V.V Sarnadsky PHD Research Institute ofTraumatology and Orthopaedics, Department of Spinal Surgery for Children and Adolescents, 630091 Frunze str. 17 Novosibirsk. RUSSIA 1. Introduction The Cotrel-Dubousset instrumentation developed in 1983 is widely applied in scoliosis surgery. Its high efficiency is convincingly proved to numerous researches [5,6 7]. However, Harrington instrumentation in its modifications (Harrington-Luque. Resina. Drummond ea.) is widely used in scoliosis correction. The comparative analysis of these methods is still an object of discussion [2, 11]. In the last years the methods of three-dimensional assessment of the dorsal surface of patients trunk are widely applied for comparison purposes of results of surgical intervention [ 1 . 4, 8]. Among them the electron optical topographical system ISIS [9] based on computer and television engineering, and also Formetic [3] and Quantec [10] in which basis the rasterstereography are most widely used. In Novosibirsk Research Institute of Traumatology and Orthopaedics in I 994 the electron-optical topographical system 'Computer optical topographer' (COMOT) was created on the basis of a method of a projection of strips and spatial detecting of a phase. It surpasses the above mentioned systems in a lot of parameters: speed of processing (1 0 seconds instead of 1 -2 minutes), spatial sanction of a restored surface, level of automation of processing. 2. Aim

The aim of the present research is the assessment of the results of the surgical treatment ol patients with adolescent idiopathic scoliosis (AIS) with the help of COMOT on two basic directions: the change of relief of the back surface of a trunk and the position of a patients' body in three-dimensional space after correction of the deformation by GDI and Harrington and during follow-up period 3. Material and methods Clinical charts, X-ray films and computer optical parameters of 71 patients with adolescent idiopathic scoliosis were investigated All of them were operated in the department of spinal surgery forthildren and adolescents in the period since January 1998 till February 2000. Depending on the method of operative treatment the patients were divided in two groups. 39

M. V. Mikhailovsk\ et al. / Three-Dimensional Correction with CD Instrumentation

217

patients, operated with application of GDI where the first group. There were 37 girls and 2 boys. Patients operated with application of Harrington rod with addition as wire loops on Drummond have come in second one. There were 31 girls and 1 boy. The average age of both groups was 14.1 years (range I 2,2 to 21,5). In 26 cases of GDI group and in 7 cases of the Harrington group the intervention was one-staged, in 13 others of GDI and 25 others of Harrington anterior discectomy and interbody fusion with autobone were performed in one session. Pre- and postoperative (one week) investigation included standing AP and lateral radiograms. Cobb angles were identified for scoliotic kyphotic and lordotic curves, apical vertebrae rotation was measured according to the Nash-Moe technique. The procedure of computer-optical topography: The patient stands before a reference plane by his back to the telechamber. With the help of a projector the picture of black-and-white vertical strips is projected on the patients' back on the surface of which strips image is deformed. This picture is processed in the computer with the special program during 10 seconds. The results are submitted in two basic forms - "lateral analysis" and sagittal-horizontal analysis. Both forms contain in total 90 parameters, from which for the present research 11 are selected: Frontal Plane • pelvic tilt • shoulder tilt • frontal balance (clinical analogue is the distance from a plumb line omitted from processus spinosus C7 to the interbuttock fold) Sagital plane • thoraco-lumbar region's inclination • pelvic sagittal inclination • kyphosis • lordosis • sagittal balance Horizontal Plane • primary curve's apex rotation • volumetric asymmetry of thorax • horizontal balance

4. Results Preoperative, postoperative and 1 year after value of radiological parameters in both groups of the patients are presented in table 1. All radiological parameters in the Harrington group decreased after operation (from 6,5% to 56,2%). All parameters got some worse lyear after operation (from 2,5% to 1 5%) and thoracic kyphosis increased on 31,5%. GDI group has the same changes (decrease from 1 3% to 5 1 %), but kyphosis increased on 1 9% right away after operation. All parameters increased 1 year after operation insignificantly (4%- 11 %), and overall kyphosis was higher in GDI group than in Harrington group (28° and 21 ° respectively). X-ray parameters were compared with computer optical parameters (Table 2). In GDI group all parameters in the frontal plane became better after operation (from 7% to 49%). In Harrington group pelvic tilt and frontal balance got worse (39% and 24% respectively). Nevertheless, shoulder tilt decreased significantly. In GDI group parameters didn't change noticeably 1 year after operation (shoulder tilt decreased 7%, frontal balance 11 % and pelvic tilt

Table 1. X-ray parameters after operation CDI

Harrington

Parameter

Before

After

%

1 year

%

Before

After

%

1 year

%

Primary curve

68,6

33,6

-51

36,1

3,6

76,5

33,5

-56,2

39,8

8,2

Secondary curve

55,9

31,1

-44,4

37,3

11,1

54,7

25,7

-53

33,9

15

Kyphosis

22,5

26,7

18,7

28,2

6,7

16,8

15,7

-6,5

21

31,5

Lordosis

48,6

42,5

-12,6

45,1

7,2

44,7

38,6

-13,6

39,7

2,5

Primary curve apical rotation

29,4

22,9

-22,1

24,1

4.1

35,6

27,1

-23,9

29,8

7,6

Secondary curve apical rotation

20,3

15,9

-21,7

17

5.4

22

16,8

-23,6

18,2

6,4

Table 2. Topographical parameters before and after operation CDI

Harrington

Parameter Before

After

%

1 year

%

Before

After

%

1 year

%

Frontal plane Shoulder tilt °

3,9

2

-49

1,7

_7

5,7

1,1

-81

1,7

11

Pelvic tilt °

1,6

1,4

-13

1,5

7

2,3

3,2

39

1,5

-74

Frontal balance (mm)

16,3

15,2

-7

13,4

-11

14,3

17,7

24

10,9

-48

Sagittal plane Thoraco-lumbar region's inclination °

17

10,5

-38

14,1

21

13,2

9,1

-31

10,2

8

Pelvic sagittal inclination °

25,3

18,2

-28

22,5

17

24,8

19

-24

19,8

3

Kyphosis (mm)

26,1

27,3

5

27,9

2

19,1

24,3

27

20,8

-18

Lordosis (mm)

27,9

21,5

-23

22,7

4

21,8

15,4

-29

17,5

10

Sagittal balance °

3,1

2,2

-29

2,4

6

2,8

2,2

-21

1,3

-32

Horizontal plane Primary curve apical rotation °

36,8

11,4

-69

23,7

33

27,5

17,4

-37

25,7

30

Volumetric asymmetry of thorax (mm)

18,6

8,1

-56

16,6

46

17,2

12,4

-28

19,2

40

Horizontal balance °

3,4

3,8

12

3

-24

6,5

6,8

5

2,8

-62

M.V. Mikh(iilo\'sk\ ct til. / Tlircc-Dimcnsutnal Correction with CD Instrumentation

increased 7%). In Harrington group parameters, that have got worse after operation, became much better I year later (from 48% to 74%). In sagittal plane all parameters decreased in the GDI group, except for kyphosis (23%38%). Sagittal balance restored significantly (on 29%). Only pelvic sagittal inclination and thoracolumbar region's inclination changed 1 year after operation (increase of 17% and 21% accordingly). This reflects the improvement of the sagittal plane. In the Harrington group the same changes occurred after operation (decrease on 21 %-31 %), but 1 year after operation sagittal balance restored (on 32%) and kyphosis decreased (on 18%). It doesn't reflect the improvement of the trunk profile. In horizontal plane primary curve apical rotation and volL-etric asymme~y of thorax decreased significantly in GDI group (on 69% and 56% accordingly), horizontal balance got worse insignificantly (on 1 2%). Partial restoration of these parameters occurred 1 year after operation (apical rotation on 33% and volumetric asymmetry of thorax on 46%), but horizontal balance became better (on 24%). In Harrington group primary curve apical rotation and volumetric asymmetry of thorax decreased too (on 37% and 28% accordingly), but horizontal balance didn't change. Nevertheless, these parameters returned 1 year after operation to that before and even more (apical rotation increased on 30% and volumetric asymmetry of thorax on 40%). Horizontal balance decreased significantly 1 year after operation (on 62%). 5. Conclusions COMOT allows not only to study features of a relief of dorsal trunk surface of the patient with high accuracy, but also to receive the information concerning a position the patient's body in three-dimensional space. Correction of adolescent idiopathic scoliosis with Cotrel-Dubousset and Harrington instrumentation leads to pronounced changes of back shape and 3-D trunk balance (Fig. 1 -6). Nevertheless, GDI leads to more even improvement of all COMOT parameters, than Harrington. Moreover, the changes during the follow-up period after GDI less than Harrington. That give a chance to prognosticate the changes in patient's trunk after surgical treatment of adolescent idiopathic scoliosis. Partial loss of correction during the follow-up period leads to back shape and trunk balance changes more than radiological changes. It tells about more deep mechanism of patient's trunk adaptation to surgical intervention than simply mechanical resistance to corrective forces. CDt is more complex and has an opportunity of applying distraction, contraction, translation and derotation simultaneously. It is more rigid in all planes and can used in correction of severe scoliosis with double curves and kyphosis. Moreover, Harrington instrumentation leads to severe changes of back shape and trunk position in three-dimensional space during a long time after surgical correction of idiopathic scoliosis. So it makes modern instrumentation like CD as more preferable than Harrington rod. References 1 .

2.

Bettany J., Forbes H., Edgar M., Harrison D. The ISIS experience at the Royal National Orthopaedic Hospital // Surface Topography and Spinal Deformity. Proceedings of the gth International Symposium. Estoril: Fischer, 1992. P.70-75. Burwell R.G., Jacobs K.J., Polak F.J., Webb J.K., Wqjcik A.S., Wytbers D.J. The back hump after Cotrel-

M. V. Mikhailo\'sk\ ct cil. / Three-Dimensional Correction with CD Instrumentation

Fig.l Back shape of patient before GDI

Fig.2 Back shape of patient after CDI

Fig.3 Back shape of patient 1 year after CDI

10. I1

221

Fig.4 Back shape of patient before Harrington

Fig.5 Back shape of patient after Harrington

Fig.6 Back shape of patient 1 year after Harrington

Dubousset, Harrington-Luque and Zielke instrumentation // Surface Topography and Spinal Deformity. Proceedings of the gth International Symposium. Fstoril: Fischer, 1992. P. 180-195. Drerup B., Hierholzer E. Back shape measurement using video rasterstereography and three-dimensional reconstruction of spinal shape. Clin Biomech, 1 994,9, 1 , pp 28-36. Edgar M.A., Bettany J.A., Ransford A.O., Harrison D.J. ISIS assessment of costoplasty: Preliminary results. In: Alberti A, Drerup B, Hierholzer B (eds) Surface Topography and Spinal Deformity. Gustav Fischer.Stuttgart, 1992, pp 83-88. Krismer M., Bauer R., Sterzinger W. Scoliosis correction by Cotrel-Dubousset in-strumentation. The effect of derotation and three dimensional correction // Spine.-1 992.-Vol. 17, No8.-P.263-269. Puno R.M., Grossfeld S.L., Johnson J.R., Holt R.T. Cotrel-Dubousset instrumentation in idiopathic scoliosis /I Spine.-1992.-Vol J7 J~o8.-P.258-262. Richards B.S., Birch J.G., Herring J.A., Johnston C.F., Roach J.W. Frontal plane and Sagittal plane balance following Cotrel-Dubousset instrumentation for idiopathic scoliosis // Spine.-1989.-Vol 14. No7.-P.733-737. Tredwell S.J., Rose R., Sawatzky B.J. ISIS review of Cotrel-Dubousset instrumentation for adolescent idiopathic scoliosis. In: Alberti A., Drerup B., Hierholzer F. (eds) Surface Topography and Spinal Deformity. Gustav Fischer, Stuttgart, 1992, pp 1 16-1 18. Turner-Smith A.R. A television/computer three-dimensional surface shape measurement system. J Biomechanics, 1988, 21, pp 515-529. Wojeik A.S., Phillips G.F., Mehta M.H. Recording of the back surface and spinal shape by the Quan~c imaging system - a new technique in the scoliotic. 1994. Wojeik A.S., Webb J.K., Burwell R.G. Harrington-Luque and Cotrel-Dubousset instrumentation for idiopathic thoracic scoliosis. A postoperative comparison using segmental radiologic analysis /I Spine.-1990.-Vol J_5 No5.-P.424-431.

Tit B. (jn\ii
Motion Analysis of the Trunk and Spine. Surface Measurement using Computer Optical Topography V.N. Sarnadskiy, S.Ya.Vilberger N.G. Fomichev Research Institute ofTraumatology and Orthopaedics, Frunze str. 17, 63009] Novosibirsk, Russia E-mail: [email protected] 1. Introduction Walking is the most natural process of the moving activity of the man. Since the end of XIX century, when the first publications in this field appeared in 1 872, a large number of researchers from various areas engaged in the analysis of gait. Today to study gait kinematics various analyzers of movement are applied, and the most modern of them are the optoelectronic computer assisted systems, such as: Selspot and McReflex (Sweden), Elite (Italy), VICON-370 and Coda (UK) etc. Such systems identif three-dimensional coordinates of passive light reflecting markers (placed in various anatomic points on a body) in dynamics and with high accuracy thus permitting to obtain much information about the gait process. However, the majority of gait kinematics studies is devoted to movement of the lower limbs, and rarely - of the pelvis [1] , leaving spine outside of the view. However, in my opinion, of a number of the authors [2,3], there is a certain link between the asymmetry of gait and development of such a severe children orthopaedic disease, as scoliosis. Among the few works devoted to the spine behavior during walking are studies performed by Belenky V. [3] and Amico M. [4]. Belenky V. solved this task by attaching gyroscopes to a body, which allow to determine an angle of lateral, forward and back inclination of the pelvis and upper thoracic spine and to quantify their rotation around a vertical axis at any phase of a step. The shortcomings of the method are attributed to the impossibility of recording linear displacements of interesting segments of the trunk, and to the essential size and weight of gyroscopes, that reduced the accuracy and reliability of results. In their pilot studies Amico M. et al. used the optoelectronic system AUSCAN, created on Elite basis with a software adapted for estimation of spine deformation. Two pairs of CCD IR cameras used in this system measured 3D coordinates of 27 passive light reflecting markers located on anatomic points of the trunk including the spinous processes from C7 to S3. This allowed to determine changes in the spine shape both in frontal and sagittal planes during movement. The main disadvantage of this method is the reception of the data on the trunk and spine shapes only from a limited number of points with markers, that, in its turn, limits its informative value and complicates the interpretation of results. Methods of optical topography allowing to receive the description of a shape in each point of a surface do not have the afore mentioned disadvantage. Asazuma T. [5] was the first to use optical topography for the analysis of gait, having applied a moire1 method for the

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examination of the patient during his walk on a place. The Moire' topogramm of a back surface was recorded on a video-recorder. The received record was looked through on a monitor screen, from which photos of separate interesting phases of the movement in a stop frame mode were taken. The photos were digitized and processed into the computer. However, the general serious lack - impossibility of complete automation of moire' topogramm processing and, by virtue of it, large labour input of the process - is inherent in the moire' method. Therefore authors were compelled to use only two parameters for the quantitative analysis: the rotation of the shoulder girdle and pelvis in a horizontal plane, and a limited number of step phases, corresponding only to peak states of legs and arms movement. This has not allowed using topography opportunities in full measure. 2.

Methods

In 1994 at Novosibirsk Research Institute of Traumatology and Orthopaedics a method of "COMputer Optical Topography" (COMOT) was developed based on a fringe projection and a spatial phase detection [6], which ensured complete automation of the processing of the measuring information. The first Russian topographical optical-electronic system (TODP) created on this basis is used to diagnose spine deformation in static poses in more than 32 medical establishments of Russia. The TODP principle of action is the following. The image of rectilinear equidistant fringes is projected on a patient's body with a projector. The shape of these fringes is deformed according to a relief of the examined surface. A TV camera registers their images and inputs them in the computer in a digital form. The shape of the patient's back surface is restored in each point of the entered image by special program processing. The numerous topographical parameters describing quantitatively the shape of a surface and estimating the spine in three planes: frontal, horizontal and sagittal, are calculated on digital surface model and anatomic landmarks of bone structures selected on it. Essential increase in the opportunities of computer facilities during the last years, including computer record of an "alive" video without compression and losses of the information, has allowed to pass from static to dynamic tasks. With this purpose the experimental setup is created based on the TODP system. This setup, in addition to the optical TODP scheme with one CCD TV camera (that have electronic shuffer no more than 1/1 000 sec) and a projector, includes computer Pentium with operative memory not less than 128 Mb, a special card for image input with the frequency of 25 frame/sec without video information compression and electromechanical running track with controlled speed of 0 to 1 6 km/hour. The use of the special image input card has allowed to register a continuous sequence of the TVframes in computer memory without omission of separate frames, and electronic TV- camera shutter has ensured the input of the dynamic images without blur. The electromechanical running track has created conditions for long filming of a walking patient without his moving with reference to the optical circuit, the depth of working space of which is essentially limited to the opportunities of an optical method. In addition the track has allowed controlling a rhythm of walking. Before examination, markers were placed on anatomic landmarks of a patient's back which included a line of spinous processes from C7 to 53, left and right iliac spines, two symmetric paraspinal points at a lumbar and thoracic junction level and two symmetric points at a level of the shoulder girdle. For this purpose the 4x4-mm markers of light reflecting film and

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additional source of illumination located close to TV-camera lens were used. The patient was firstly examined in their natural orthostatic position, then the track was switched on with given speed and after certain period of walking on a track the patient was filmed during the given time interval. All the information as a sequence of the television frames was firstly recorded in main computer memory, then on a hard disk and after that it was ready for the subsequent processing. 3.

Results

In Fig. 1 - 6 the results of a 10-year-old patient examination with experimental setup of dynamic topography are given. Fig. 1 shows a series of time consecutive digitized TV-frames (with frequency 25 frames/sec). This series demonstrates a half of a complete cycle of a step starting with the left-leg-support state and finishing with the right-leg-support state. After processing of the frames it is possible to restore a digital model of the whole surface for each of them which provides the complete information on changes in the shape of back surface and its position during walking in three-dimensional space. Fig. 2 depicts the topogramms of patient's back surface received after restoration of digital model of the appropriate series of frames in Fig. 1 (the step between fringe - 5 mm). Fig. 3-5 show another graphic presentations of the same series of frames of the back surface in three planes: frontal, horizontal and sagiffal, allowing most evidently to display a shape of the back and spine during walking. These graphic presentations of a surface are intended for the detailed and profound analysis ofthe interested frames. For interpretation of data ofthe whole observation interval, the plots of any topographical parameter describing a condition of a surface, can be constructed as shown in Fig. 6. Vertical dotted lines on Fig. 6 limit a time interval appropriate to a series of frames in Fig. 1 . For example, the plots shown in Fig. 6a 6e describe orientation of a trunk in space. Fig. 6a shows a trunk inclination (angular position of C7 relative to the sacrum at 53 level) and pelvic inclination (position of a line connecting posterior iliac spines) in the frontal plane. Fig. 6b shows shoulder girdle and pelvic rotation in the horizontal plane. Fig 6c shows trunk (angular position of C7 relative to the sacrum at 53 level) and pelvic inclination in the sagittal plane. Fig 6d describes the inscribed angle of lumbar lordosis and of thoracic kyphosis. Fig 6e shows maximal lateral deviation ofthe spinous processes from line C7- 53 in the frontal plane to the left and to the right accordingly. The given example illustrates essential advantage of a method of dynamic topography in comparison with other systems of movement analysis. This advantage is a result of the most detailed registration of a trunk surface behavior during movement and the possibility of evaluation of three-dimensional coordinates in any point of this surface for each frame.

V.N. Sarnadskiy et til. /Motion Analysis of the Trunk and Spine

Fig. 1. A series of the consecutive TV frames which demonstrates the transition from a state of support on the left leg to a state of support on the right leg.

Fig. 2. Topogramms of the patient's back surface during walking

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Fig. 3. Frontal views of the patient's back surface

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Fig. 5. Sagittal views of the spinous processes line on the patient's back surface

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4.

Conclusion

Performed pilot studies have shown that the suggested method of dynamic topography offer new opportunities for gait analysis, providing precision and detailed information on spine and trunk during walking. We consider that this method in combination with other methods of gait analysis will allow to study the spine biomechanics more deeply and to answer many urgent questions of spine pathology, including the influence of gait asymmetry on scoliosis development. In combination with modern computer technologies of image processing this technique allows to realize the analysis of gait kinematics at a qualitatively new level, providing an opportunity of visualization of movement process in its natural form with obtaining of great interest quantitative information in any volume.

References [1] Harris G. F., Smith P. A. Human motion analysis. IEEE press, 1996. [2] Dangerfield P.et al., Gait Analysis of Patients with Adolescent Idioplastic Scoliosis, in M. D'Amico, A.Merolli, G.C. Santambrogio Eds.) Three Dimentional Spinal Deformity Proc. Of the 2nt Int Sym. On 3D Scoliotic Deformities Pescara Sep. 1995 IOS Press pp. 297-301. [3] Kaauora A. H., KOH H. H., EeneHucHfl B. E. CKOJIHOS. - M.: Meflwama. 1981. [4] Amico M. D., Roncoletta P. Biomechanical Analysis of the Spine During Walking. A pilot Study. In: Sevastic J. A. and Diab (Eds.) IOS Press - Technology and Informatics: Research into Spinal Deformities 1., Vol. 37 ISSN: 0926-9630, 1997, pp. 161-164. [5] Asazuma T., Suzuki N., Hirabayashi K.. Analysis of human dynamic posture in normal and scoliotic patients. Proc.of IE Int. Sym.Surface Topography and Spinal Deformity, Gustav Fisher Verlag, Stuttgrt, New York, 1986. [6] CapaucKHft B. H., CaaoBofi M. A., QOMDPKB H. F. CnocoG KonnuorepHoft ormiHecicott Tonorpa4)HH rejia lenoBexa H ycrpoflciBO AIM ero ocymecTMeHJM. EBparaftCKHfl naremr Jfe 000111, i. 1996.

77i.fi. Gmas(EiL) Research into Spinal Deformities 4 1OS Press, 2002

Development of the neurocentral junction as seen on magnetic resonance images T. Rajwani*, R. Bhargava*, R. Lambert*, M. Moreau+, J. MahoocH-, V. J. Raso+, H.Jiang+, E.M. Huang, X. Wang, A. Daniel and K.M. Bagnall Division of Anatomy/Dept of Radiology and Diagnostic Imaging/* Dept of Surgery, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7 Tel. 780-492-7094 Fax: 780-492-0462 Email [email protected] Abstract. The neurocentral junction (NCJ) is a cartilaginous growth plate in the vertebra that has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS) since the early 1900s. Studies to date have focused on the age of closure without characterizing normal NCJ development. Using MRI, the normal development of the NCJ image can be determined and the stages preceding the disappearance of the NCJ image can be characterized. 405 NCJs from 11 pediatric patients were examined using MRI and the various images were categorized. NCJ development encompassed five stages, with a specific pattern of absence of the NCJ image noted in each vertebra and in the vertebral column as a whole. The image of the NCJ first became absent in the cervical region (age 6), then in the lumbar region (age 12) and finally in the thoracic region (age 14). These patterns of development serve as a baseline to evaluate NCJ pathology in conditions such as adolescent idiopathic scoliosis (AIS).

1. Introduction The cause of adolescent idiopathic scoliosis (AIS) remains a mystery despite extensive research over many years [I]. Since the early 1900s, the neurocentral junction (NCJ) has long been considered a potential cause of AIS. The NCJ is a cartilaginous growth plate located between the neural arch and the centrum of the vertebra (Fig. la,b). Unlike other epiphysial plates, this growth plate is truly bipolar and is considered to be important in the growth of both the vertebral body and the posterior arch [2,3,4,5]. Consequently, it has been hypothesized that disparate growth or unilateral closure at mis junction could lead to vertebral deformation and, ultimately, the development of abnormal spinal curves [4,5,6,7,8]. The idea of disparate NCJ growth being a possible cause of AIS was abandoned in the past, after gross anatomic and histologic studies suggested that the NCJ closed before the age often in humans [4,6,8,9,10]. However, recent MRI studies of the NCJ have resurrected the unilateral closure hypothesis, by suggesting that the NCJ does not close until 11-16 years of age [5]. Before the development of the NCJ in AIS patients can be assessed for abnormal development, it is necessary to determine the normal characteristics of the NCJ image. In this study MRI techniques were used to characterize normal NCJ development patterns, which could serve as a baseline for future assessment of abnormal development.

f Rajwani ft til. / Development of the Nenroccntral Junction

Figure la (left). Drawing of the position of the NCJ (arrows) in transverse view. Figure Ib (right). Drawing of the position of the N~J (arrows) in sagittal view.

2. Methodology Four hundred and five NCJs from li normal pediatric patients (6 males and 5 females, age range 2 months-15 years) who underwent MRI were examined. Patients were only included in the study if they had no abnormal findings on MRI examination and no clinical history of conditions that would have affected vertebral growth (e.g. neoplastic growths, muscular abnormalities, scoliosis, neurological conditions and vertebral abnormalities). MR imaging was performed using a 1.5 T imager (Siemens) and both T2 transverse and sagittal views were acquired (TR = 3100, TE = 120, slice thickness = 3.0 mm). In some patients. Tj transverse and sagittal views were also acquired for comparison. MR images were examined randomly after patient information was removed. The appearance of the NCJ image was recorded both digitally and as a schematic drawing. The complete NCJ was usually seen on sagittal view as a composite of two images and these composite pairs of images were sorted into five categories (Table 1). The five categories of NCJ appearance were placed in sequential order to represent developmental stages. The latest age at which the NCJ of a particular vertebra was classified as greater than 50% present (Stage 3) and the earliest age at which the NCJ was classified as less than 50% present (Stage 4) were noted. The arithmetic mean of these two ages was taken to represent the midpoint of the window of time when the image of the NCJ started to become absent. This measurement was more valuable than simply determining when the image of the NCJ was no longer present, since the latter encompasses an extremely large window of time and would be much less useful as a marker of vertebral development. This measurement was used to compare NCJ development between different regions of the vertebral column.

3. Results The image of the NCJ was clearly visible on the T2 weighted images as a low intensity black line located posterior to the centrum. This line was easy to identify in young patients since it appeared continuous within adjacent vertebrae. In older patients, this line was discontinuous across large sections of the vertebral column, but could be discerned by its position and intensity among several adjacent, consecutive vertebrae (Fig. 2a,b).

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In this study, the T2 sagittal images were the most valuable. The T2 weighted views provided better visualization of the NCJ than the T\ images. The sagittal images were preferred to the transverse images since more vertebrae could be assessed in a given acquisition time.

Figure 2a (left). NCJs (arrow) in the thoracic region of a 2 year-old femaTe appear as thick low intensity black lines that are continuous throughout the vertebrae. Figure 2b (right). In a 12 year old male, the low intensity line of the NCJ (arrow) became thinner and lighter in color. The NCJ images were not continuous throughout the vertebral column, but were only visible in two or three consecutive vertebrae.

In the sagittal plane, there were usually two images of the NCJ on either side of the midline (296/405), although there was sometimes a single view (76/405) or three views (33/405). In the cases where three views of the NCJ were seen, only two views were dominant with the third view showing only a portion of the NCJ. The T2 transverse views clearly showed that the lateral border of the image of the NCJ became absent before the medial border (Fig. 3). After examining the T2 sagittal views, it was noted that each individual image of the NCJ in the sagittal plane became fragmented with development. In 141 sagiffal views of the NCJ, there was a difference noted between the superior and inferior portions of the image of the NCJ. In 86.5% of cases (122/141 NCJ), the sagittal image of the NCJ showed that the NCJ first became less visible in the middle section between the clearly defined superior and inferior areas (Table 1). The different fragmentation patterns in the sagittal plane permitted the identification of three distinct variations of an individual image of the NCJ. Since there were generally two views of the NCJ on either side of the midline, these three variations occurred in different combinations, resulting in five possible views for any partic~ar NCJ with two possible variations at stage 3 (Table 1). Using these developmental stages, a difference between the right and left NCJ images was seen in 34/143 pairs (23.8%) of NCJs where there were at least two adequate views of the NCJ on either side of the midline. Among these 34 pairs of images, there were 17 cases where the right-sided image was more advanced in terms of the developmental stage and 17 cases where the left-sided image was more advanced. This difference in right and left development usually involved one developmental stage, except for seven cases where a difference of two developmental stages was noted.

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T Rajwunt ct cil. / Development of tin- Ncurocentral Junction

By staging each NCJ in the same patient and arranging these images in chronological order, it became clear that the image of the NCJ became absent in a sequence along the vertebral column although this was not very precise in terms of vertebral level (Fig. 4).

Figure. 3. T., MRI of the sixth thoracic vertebra from a 16 year old female patient Both sides of the vertebra show a clear lateral to medial disappearance of the NCJ (arrows).

Figure 4. Age of closure of the NCJ at different vertebral levels

The low intensity line first became absent in the lower cervical region at the age of 6 and then became absent in both cranial and caudal directions. At the thoracic 1 and thoracic 2 levels, the image of the NCJ became absent around the age of 10. Absence of the NCJ images was next noted in the lumbar region at age 12, with the NCJ images becoming absent progressively later in the cranial direction. By age 13, the image of the NCJ had become absent in the entire lumbar spine. By age 14, the NCJ image was not visible at the T9-T 12 vertebrae. The image of the NCJ was present for the longest time period in the midthoracic region (T4-T8), where the image remained until age 15 (Table 1).

4. Discussion With the advent of MRI, the NCJ can be imaged in- situ and its development determined. The NCJ image can be precisely defined as a low intensity line seen posterior to the centrum.

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233

Within an individual vertebra this image becomes absent from lateral to medial and from the middle towards the superior and inferior borders. In addition, this study shows that there is only a small window of time during which the image of the NCJ changes from a very intense dark line to becoming completely absent. This window of time, of approximately two years, may be useful as a milestone of vertebral development. Table 1 Distribution of NCJ by Stage. The drawings represent the two MR slices taken through a single NCJ. The black areas represent the presence of the NCJ image, whereas the areas of no black correspond to the absence of the image. The stages are arranged in developmental sequence, with each NCJ passing through either stage 3a or stage 3b. Only 329/405 NCJ were staged, since there was only one view of the remaining NCJs. If there were three views of the NCJ (33/329), the two most prominent views were used for staging.

In terms of regional patterns, the NCJ shows a sequence of development along the vertebral column (Fig.4), with absence of the NCJ image first occurring in the cervical spine (6-7 years), then in the lumbar spine (11-12 years) and finally in the thoracic spine (10-15 years). Interestingly, this pattern of NCJ development parallels the sequence of ossification of the neural arch centers in the fetus [11]. The finding that the image of the NCJ becomes absent last in the midthoracic region is significant when AIS is considered, since it implies that the midthoracic NCJs likely have the longest time to develop and thus the greatest possibility of potentially asymmetrical growth. This would correlate with the high incidence of apical scoliotic vertebrae in this region in AIS patients [1,13]. In both this study and that of Yamazaki [5], it was assumed that the image of the NCJ correlated with an open growth cartilage and the absence of this image correlated with a closed one. The validity of this assumption remains to be proved especially when autopsy studies and imaging studies have produced conflicting results. To examine this idea, we are currently correlating histological images of the NCJ with corresponding MR images. In this study, the small number of subjects prevented any gender comparisons from being made. Yet, the well-defined difference in bone development between males and females would suggest that there may be slight differences in the age at which the image of the NCJ becomes absent [12]. Furthermore, based on the fact that most adolescents exhibit a slight right scoliosis [10,13], it would be predicted that the left NCJs would show advanced development in some cases. A larger population is needed to assess these ideas. In summary, the characterization of the NCJ image provides a means to compare vertebral

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T. Rajwani ct al. / Development of the Veiiroccntml Junction

development at different times and in different pathological circumstances, regardless of the significance of this image. A determination of the normal pattern of development of the NCJ is absolutely essential before the NCJ can be evaluated for abnormal or disparate development in AIS patients.

5. Acknowledgements The authors would like to thank Ms. Nina Nathoo for the illustrations, the Edmonton Orthopaedic Association for research funds, and the Alpha Omega Alpha Research Fellowship programme for providing a scholarship to T.R.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 2. 3. 13.

R.C. Robin, The Aetiology of Idiopathic Scoliosis. CRC Press, Boca Raton, 1990. G.J. Maai, B. Matricali, E.L. Van Meerten, Postnat- development and structure of the neurocentral junction, Spine 21:6(1996)661-66. G. To~ndury, K. Theiler, Entwicklungsgeschichte und FehTbildungen der wirbelsa~ule, 2-d edn. Hippokrates Verlag, Stuttgart, 1990. J.M. Vital, J,L. Beguiristain, C. Algara et. al.. The r-e—centr- vertebral cartilage: anatomy, physiology and physiopathology, Surg —adioIAnat 11(1989)323-28. A. Yamazaki, D.E. Mason, P.A. Caro, Age of closure of the neurocentral cartilage in the thoracic spine. J ofPed Ord-o 18 (1998) 168-172. F. Knutsson, Vertebral genesis of idiopathic scoliosis in children, Acta Radial 4 (1966) 395-402. J.E Michelsson, The development of spinal deformity in experimental seoliosis, Acta Orthop Scand 36:supp 81 (1965) 9-91. R. Roaf, The basic anatomy of scoliosis, Ji of Bone and Joint Surg - Bntish 48 (1966) 786-92. G. Schmor-, H. Junghanns, E.F. Besemann (ed.) The Human Spine in Health and Disease. Grune and Stratton, New York and London, 1971. J.R. Taylor, Scoliosis and growth : patterns of asymmetry in normal vertebral growth, Acta Orthop Scand 54(1983)596-602. K.M. Bagnall, P.F. Harris, P.R.M. Jones, A radiographic study of the human fetal spine : 2. The sequence of development of ossification centres in the vertebral column, J of A not 124 (1977) 791-802 D. Sinclair, Human growth afterbirth,
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The components of the magnetic resonance image of the neurocentral junction T. Rajwani*, E.M. Hilang, C. Secretan, R. Bhargava*, R. Lambert*, M. Moreau+, J.Mahood+, V. J. Raso+, and K.M. Bagnall Division of Anatomy/Dept of Radiology and Diagnostic Imaging/* Dept of Surgery, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7 Tel. 780-492-7094 Fax: 780-492-0462 Email [email protected]

Abstract. The neurocentral junction (NCJ) is a cartilaginous growth plate located between the vertebral centrum and the neural arch. In characterizing the age of closure of this growth plate, anatomic studies have suggested that the NCJ closes before age 10, whereas MRI studies have suggested that the NCJ does not fuse until adolescence In this study, gross anatomic and histologic sections were correlated with MR images to determine the components of the NCJ image. The NCJ image appeared as a thick white line that was shown to encompass the cartilage of the growth plate, the surrounding woven bone and a portion of the trabecular bone of the vertebra. Although the MR pixels were too large to completely resolve the tissues that surround the growth plate, MRI was shown to be a valuable technique of visualizing the NCJ cartilage and further MRI studies of the human NCJ are needed.

1.

Introduction

The neurocentral junction (NCJ) is a cartilaginous growth plate located between the neural arch and the centrum of the vertebrae. Since the early 1900s, it has been hypothesized that unilateral growth at this site could lead to vertebral deformation and the development of abnormal spinal curves [1,2,3,4,5]. In this regard, the NCJ has long been considered a potential cause of adolescent idiopathic scoliosis (AIS). Before the unilateral closure theory of AIS can be accepted, the age of closure of the NCJ must be determined. If the NCJ closes before adolescence, then AIS cannot be attributed to this cause. To date, studies on NCJ closure have been highly controversial. Whereas anatomic studies have suggested that the NCJ closes before age 10 [2,3,4,6,7], a recent MRI study by Yamazaki et al. has suggested that the NCJ does not close until 11-16 years [5]. In Yarnazaki's study, the presence of a black line on MRI was thought to correspond to an open NCJ and the absence of this line was thought to show NCJ closure. To verify this assumption, MR images of the NCJ must be correlated with anatomic and histologic sections in performing a correlation, Yarnazaki's imaging protocol would be somewhat ambiguous since it would result in both cartilage and compact bone presenting as black regions on MRI. This would mean that a black line could represent a closed NCJ, with layers of compact bone on either side, or an open NCJ, with intervening cartilage present between layers of

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T Rajwimi ct al. / The ('<>nt[)i»t<'nl.\ i>( the Magnetic Resonance Inutin

compact bone. In this study, imaging parameters were altered so that compact bone and cartilage appeared as different intensities. MR images of the NCJ were precisely correlated with sections taken at the same sites to determine the components of the NCJ image. 2. Methodology MRI Study The thoracolumbar vertebral column was harvested from a six month old pig and MR images were acquired using a 1.5 T system (Siemens). After acquiring images with a variety of sequences such as DESS, TSE, SE, ORE and MEDIC, it was qualitatively determined that the Tj DESS sequence (TR=22.4, TE=6.0) allowed the clearest visualization. This sequence was used to acquire sagittal and transverse images (slice thickness = 1.0 mm) throughout the entire porcine spine. Anatomic Study/Sectioning After image acquisition, the vertebral column was dissected into individual vertebrae (13 thoracic, 6 lumbar). To characterize the NCJs from a gross anatomic perspective, these vertebrae were careftilly inspected from the lateral surface for any evidence of open NCJs. Next, the NCJs were characterized by sectioning and staining. Using the "scout image" from the MR images, each vertebra was sectioned at the precise spot that the images were acquired. The precise site of sectioning was determined using the external three-dimensional coordinate system of the MR magnet. Using a Tech-Met bone cutter and a Buehler diamond wafering blade (thickness=300 Jim), the vertebrae were sectioned at successive distances of 1.0 mm to match the positions of the 1.0 mm DESS images. Using this procedure each section was approximately 700u,m in thickness. There was a 300ujn gap between sections, which matched the thickness of the wafering blade. To allow for correlations in more than one plane, half of the sectioned vertebrae were cut sagitaily and half were cut transversely. Both surfaces of each section were digitally photographed with an external ruler placed by the section. After photographs were taken, specific sections were stained to allow better visualization of the cartilage. Staining was performed by immersing the sections in 0.1 % toluidine blue for 5 seconds. The stained sections were viewed under IOOX and 2 SOX magnification, with photos taken at both magnifications. Correlation Procedure The MR images were photographed with an external ruler included in the image, which was used to determine the magnification of the image in the digital photograph. By measuring the distance between several bony landmarks on the MR image and the corresponding histotogic sections, the magnification of the image relative to the true specimen was determined. Using these magnifications, the magnification of the digital photo relative to the true specimen was determined and the histologic image was converted to the same size as the MR image. Since the sections were taken at precisely the same site, the histologic image could then be overlayed on top of the MR image to permit correlation. This correlation was achieved using the variable opacity function in Adobe Photoshop 4.5. At this point, the histologic image was simply rotated to match the correct rotation of the MR image without further alterations in size or position. To determine further the composition of

T. Rajwani ct al. / The Components of the Magnetic Resonance Image

the MR image, the line representing the NCJ on MRI was also correlated with the 1 OOX and 250X views of the histologic sections taken at the same site. To ensure that several neighboring histologic slices could not be correlated with a given MR image, correlations were also attempted for histologic sections of the NCJ that were approximately 1.0 mm away from the position of a given MRI slice. 3. Results It was anticipated that the NCJs in this specimen would be clearly visualized, since prior studies have found that the porcine NCJ does not fuse until the age of one year [8]. However, it was extremely difficult to determine if the NCJ was open or closed solely on the basis of gross visualization of the intact vertebrae. The NCJ could not be visualized by gross examination from the superior or the inferior surfaces, since the pig exhibits true epiphysial growth plates at the superior and the inferior surface of the vertebra. The NCJ could be faintly seen on examination of the lateral surfaces of the vertebra after extensive removal of the periosteum. This visualization could not be consistently achieved in all vertebrae, although a typical case of visualization is shown in Fig. la. Using even just a 30 gauge needle, the site of the NCJ cartilage could not be discerned by probing at periodic intervals and feeling for a difference in needle penetration (Fig. Ib). Upon sectioning, the NCJ was readily visible in most sagittal sections as an undulating line between the vertebral centrum and the neural arch (Fig. 2a). The NCJ was continuous with the superior and the inferior physeal growth plates. In transverse section, the NCJ stretched from the vertebral canal to a region between the centrum and the vertebral arch. The NCJ did not extend through the periosteum (Fig. Ib), which would account for the difficulty in finding the NCJ on gross visual examination. The thin width of the NCJ in the sagittal plane would account for the difficulty in finding this site with a needle (Fig. Ib). Microscopic visualization revealed that the NCJ growth cartilage is truly bipolar as suggested by Tondury et al. [9], with growth columns and deposited bone being found on both the anterior and the posterior surfaces (Fig.5). In performing the histologic-MR correlation, the DESS sequence allowed the differentiation of cartilage, which was hyperintense and compact bone, which appeared hypointense. In performing axial and sagittal correlations at different levels, it was apparent that the white line seen on MRI encompassed the NCJ cartilage (4a,4b,4c), although this

Figure la (top). Gross visualization of the T5 vertebral body from the left side revealed a subtle interface (seen in the rectangular region) which corresponded to the site of the NCJ. Figure Ib (bottom). Digital photograph illustrates that the NCJ (arrows) does not extend through the periosteum. The cartilage within the. junction is quite thin, as shown by the comparison to the diameter of the 30 gauge needle seen on the right.

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Figure 2a (left). Sagittal section through the lateral portion of the L3 vertebra illustrates that the NCJ is readily visible (arrow). The anterior border is on the left. Note that the NCJ appears to be continuous with the superior and inferior epiphyseal growth cartilages. Figure 2b (right). Transverse section through the L2 vertebra illustrates that the NCJ is readily visible on the right and the left side (arrows).

white line was much thicker than the hyaline cartilage. Upon correlation of the NCJ image with the corresponding histologic section (250X), the white line on MRI was seen to encompass the newly deposited bone on either side of the growth plate (Fig. 5) and even a portion of the trabecular bone of the vertebra. Sections located 1.0 mm away from the position of a particular MR slice generally correlated to a much lesser degree than the sections taken at the same position (Fig. 4d). This confirmed that the NCJ at a particular vertebral level generally had enough characteristic features to allow for strong one-to-one correlation of MR images and histologic sections. If the NCJ was fairly uniform throughout a vertebra, it would be more difficult to verify that MR images and sections were being acquired at the same positions.

Figure 4a (top left). Magnified MRI from T6. Figure 4b (top right). Transverse section from T6 taken at the same position as MRI in 4a. Figure 4c (bottom left). Correlation of the transverse section in 4b with the MRI in 4a. The cartilage of the NCJ was traced with a white line (which spans between the white arrows), which fell directly on top of the white line seen on MRI. The white line of the MR image was significantly thicker than die cartilage, but occurred in the same position. Figure 4d (bottom right). Correlation of the transverse section located 1.0 mm below the section in 4b with the MRI (NCJ image shown by white arrows) in 4a shows a poor correlation. The NCJ cartilage is traced as a thin white line and seen above the black arrows.

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Figure 5 The white image of the NCJ seen on MRI (shown by the area between the thin white lines) encompassed portions of the NCJ cartilage, the woven bone on either side of the growth plate and the trabecular bone of the vertebra. The square on the diagram represents the approximate size of an MR pixel in relation to the growth plate.

4. Discussion This study represents the first characterization of the NCJ using a combination of gross anatomy, histology and MRI. Gross visualization of the lateral surface of the vertebral body was not an effective technique for visualizing the presence of the NCJ, since the NCJ does not extend through the periosteum. In contrast to gross visualization, sectioning clearly showed the NCJ in both transverse and sagittal planes, although this technique is obviously inappropriate for clinical use. Using MRI and the 1.0 mm DESS sequence, an undulating white line could be seen at the precise position of the NCJ. Upon correlation of the MR image with the histologic section, it was apparent that this white line encompassed the NCJ cartilage, the surrounding woven bone and a portion of the trabecular bone. The fact that the NCJ image includes cartilage is hard to dispute, since cartilage would account for the hyperintense nature of the image. It is somewhat surprising that trabecular bone and woven bone are being incorporated into this white line, since both of these tissues should appear black on the DESS sequence. The increased thickness of the line on MRI arises because the MR pixels used (dimensions = 0.3 mm x 0.4 mm) were unable to differentiate distances on the order of microns (Fig. 5). The cartilage and adjoining woven bone in the NCJ span approximately 800 u,m and were therefore represented by only two pixels. Within these pixels, the hyperintense cartilage signal overwhelmed the hypointense bone signal, resulting in a white line thicker than the true cartilage. Based on this explanation, the white line seen on MRI represented a composite of cartilage, woven bone and trabecular bone. However, the hyperintense nature of this line was solely due to the cartilage. Without cartilage in the NCJ region, one would expect the NCJ image to be much more hypointense, similar to the trabecular bone seen in the rest of the vertebra. Although it could be suggested that the next step would be to use smaller MR pixels to allow finer discrimination, this may not be necessary for the determination of the age of closure of the NCJ. Since only cartilage appears hyperintense on the DESS sequence and all bone appears hypointense, any signal that is more hyperintense than bone reflects the presence of cartilage and an

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open NCJ. Although it would still be useful to visualize a closed NCJ with the DESS sequence, this work suggests that the DESS sequence may have the potential to conclusively determine the age of NCJ closure in living subjects. References 1. 2. 3. 4. 5. 6. 7. 8. 9.

JE. Micheisson, The development of spinal deformity in experimental scoliosis, Acta Orthop Scand36:supp 81(1965) 9-91. F. Knutsson, Vertebral genesis of idiopathic scoliosis in children, Ada Radial 4 (1966) 395402 R. Roaf, The basic anatomy of scoliosis, Journal of Bone and Joint Surgery - Bntish Volume 48 (1966) 786-92. J.M. Vital, J.L. Beguiristain, C. Algara et al., The neurocentral vertebral cart-age: anatomy, physiology and physiopathology, Surg Radiol Anat \ 1(1989) 323-28. A. Yamazaki, D.E. Mason, P.A. Caro, Age of closure of the neurocentral cartila~e in the thoracic spine, Journal ofPediatric Orthopaedics 18 (1998) 168-172. G. Schrnorl, It. Junghanns, E.F. Besemann (ed.) The Human Spine in Health and Disease. Grune and Stratton, New York and London, 1971. J.R. Taylor, Scoliosis and growth patterns of asymmetry in normal vertebral growth, Acta Ortl~op Scand 54 (1983) 596-602. HG. Ottander, Experimental progressive scoliosis in a pig, Acta Orthop Scand 33 (1963)91-7. G. To~ndury, K. Theiler, Entwicklungsgeschichte und Fehlbiidungen der Wirbelsaule, 2~d edn. Hippokrates Verlag, Stuttgart, 1990.

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Accuracy of rasterstereography versus radiography in idiopathic scoliosis after anterior correction and fusion Lars Hackenberg1, Eberhard Hierholzer2, Ulf Liljenqvist 1 1

Klinik undPoliklinikfur Allgemeine Orthopddie 2 Institutfiir Experimentelle Biomechanik Universitat Miinster, Germany

Abstract. Rasterstereography enables to reduce the number of radiographs in the conservative treatment of idiopathic scoliosis (Cobb angles below 50°). The aim of the present study was to evaluate the use of rasterstereography in severe scoliosis before and after anterior surgery. The results show that the accuracy (as compared to radiographs) is lower in the pre-operative rasterstereographs. However, after operation the Cobb angles were less than 50 ° in all cases and the accuracy of the rasterstereographs was similar to that of non-operated scolioses. This finding might allow a significant reduction of postoperative radiographs.

1. Introduction By means of Rasterstereography the number of radiographs in the conservative treatment of idiopathic scoliosis with Cobb angles up to 50 F could be effectively reduced [1]. Based on comparisons of digitized radiographic and rasterstereographic data of 114 patients the reliability of the system could be proven for scoliosis with Cobb angles up to 50 F [2]. The rms differences of lateral deviation amounted to 4 mm and that of vertebral rotation to 3 F. So far the system was evaluated for non-operatively treated moderate deformities only. This study works on the application of rasterstereography on severe scoliosis with Cobb angles higher than 50 F which were operatively treated by Zielke or Halm-Zielke instrumentation (YDS) [3,4]. The aim of the study was to evaluate the system's accuracy in scoliosis with severe back surface deformity and in anteriorly corrected and fused deformities. From the literature no data on three-dimensional back surface analysis after anterior surgical correction of spinal deformities are available. Furthermore the aim of the study was to reduce the number of indispensable postoperative X rays. If the system works reliably in VDS-treated patients the number of X rays and perhaps the cancer risk [5] can be reduced considerably. 2. Materials and Methods Fifty-two patients (age 13-26 years, mean 17.7 years) with thoracic, thoracolumbar and lumbar idiopathic scoliosis who underwent Zielke or Halm-Zielke instrumentation were examined. Minimum postoperative follow up was two years (27-62 months, mean 37.6 months). Ten patients underwent Zielke instrumentation and 42 Halm-Zielke instrumentation.

L. H(ickenheri> cr ni / Accuracv of' Rasierstereographv versus Radiograph*

The patients were examined pre- and postoperatively by rasterstereography and radiography in relaxed standing posture. The radiographs were digitized according to the method of Drerup [6,7]. This method allows an accurate determination of lateral deviation, Cobb angle and vertebral rotation. In particular the postoperative measurement of vertebral rotation is more precise than conventional non-digital methods owing to the calculation of smooth curves instead of pointwise segmental measurements. The similarity of rasterstereographic spinal reconstruction and the radiographic skeletal deformity was quantified by means of best-fit superimposition of the two curves and calculation of the root mean square (rms) differences of corresponding lateral deviation and rotation curves according to the method of Drerup and Hierholzer [8,9,10], see Fig. 1. Instead of local features the whole shape of both curves was taken in account.

Fig.l Comparison of radiographic and rasterstereoraphic spine curves before and after anterior surgery (52° thoracolumbar)

The location of vertebra prominence used for the longitudinal fitting of the

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rasterstereographic curves is determined automatically, but slight manual corrections (±30mm) could improve the results. This has to be attributed to the fact that the position of C7 may deviate from the location of the bulge produced by its spinal process. Moreover the vertebra prominence may even be produced by C6 or Tl. Furthermore, different torsions between pelvis and shoulder in the relevant rasterstereographs and radiographs were considered as systematic errors due to possible posture variations and corrected before the curve comparison (correction of trunk torsion). In addition to the calculations of the curve comparisons the correction of the Cobb angles were determined from the digitised radiographs. 3. Results T he Cobb angles of the instrumented primary curves of the deformities could be reduced from 57.2 F (52-88 F) to 17.2° (6-34 F). The non-instrumented thoracic secondary curves corrected spontaneously from 34.5 F (16-48 F) to 21.5 F (7-43 F).

Table 1: Comparison of lateral deviation and vertebral rotation curves measured from rasterstereographs and digitised radiographs Note: A few rasterstereographs and radiographs were not taken on the same day, therefore some radiographs were compared with more than one rasterstereograph.

For the curve comparisons 149 radiographs (48 preoperative) were compared with 173 rasterstereographs. A few of them could not be taken on the same day. Therefore some radiographs were compared with more than one rasterstereograph. The comparisons of the lateral deviation curves showed a rms difference of 6.4 mm pre- and 3.4 mm postoperatively. The comparisons of the vertebral rotation curves without correction of systematic trunk torsion showed a rms difference of 5.3° preoperatively and 4.1° after surgery. With correction of trunk torsion the rms difference was 4.5° pre- and 3.2° postoperatively (Table 1). Particularly poor

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results of the curve comparisons in the preoperative group were analysed regarding the sources of error. The underestimation of the rasterstereographic vertebral rotation in the apical region of the deformities in the automatic reconstruction of the spine was a frequent problem in severe scoliosis and was considered to be the most important reason for the limited accuracy in the preoperative group. 4. Discussion A technique for a fast and objective quantification of the postoperative cosmetic improvement and both vertebral and back surface derotation appears to be helpful in scoliosis surgery. This investigation proved a good precision of the method in scoliosis corrected and fused by anterior surgery. The rms difference of lateral deviation and vertebral rotation is comparable with that found in scolioses below 50 F Cobb. This could be expected because after surgery the Cobb angles were lower than 50 F in all cases and no posterior implants or scars disturbed an accurate back surface analysis. The results of the comparison of the preoperative radiographic and rasterstereographic curves showed higher rms differences compared with those of scolioses below 50 F Cobb and of postoperative scolioses. In these severe scoliosis with Cobb angles higher than 50° the rasterstereographic curve reconstruction is reliable but its accuracy is limited to 6.4 mm lateral deviation and 4.5 F vertebral rotation on average. The comparison of MRI and rasterstereography in another examination [11] revealed that an underestimation of the vertebral rotation particularly at the apex causes the reduced accuracy of rasterstereography in severe scoliosis. 5. Conclusion The accuracy of rasterstereography in scoliosis after correction and fusion by anterior surgery is good and comparable with that of non-surgically treated deformities with similar Cobb angles. The accuracy in severe idiopathic scoliosis with Cobb angles of more than 50° is satisfactory. In future, the precision of the device may be improved by comparing MRI scans with rasterstereographs and developing new mathematical models. The authors hope to significantly reduce the postoperative radiation exposure of surgically treated patients with idiopathic scoliosis. References 2.

U. Liljenqvist, H. Halm, E. Hierholzer, B. Drerup, M. Weiland. Three-dimensional surface measurement of spinal deformities using video rasterstereography. Zeitschrift fur Orthopedic und ihre Grenzgebiete 1998; 136:57-64

3.

B. Drerup, E. Hierholzer. Back shape measurement using video rasterstereography and three-dimensional reconstruction of spinal shape. Clinical Biomechanics 1994; 9:28-36

4.

K. Zielke. Ventral derotation spondylodesis. Results of treatment in cases of idiopathic lumbar scoliosis. Zeitschrift fur Orthopedic und ihre Grenzgebiete 1982; 120:320-329

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5. H. Halm, U. Liljenqvist, T. Niemeyer, D.P.K. Chan, K. Zielke, W. Winkelmann. Halm-Zielke instrumentation for primary stable anterior scoliosis surgery: Operative technique and 2-year results in ten consecutive adolescent idiopathic scoliosis patients within a prospective clinical trail. European Spine Journal 1998; 7:429-434 6.

M. Morin Doody, J.E. Lonstein, M. Stovall, D.G. Hacker, N. Luckyanov, C.E. Land. Breast cancer mortality after diagnostic radiography: Findings from the U.S. Scoliosis Cohort Study. Spine 2000; 25:2052-2063

7.

[B. Drerup. Principles of measurement of vertebral rotation from frontal projections of the pedicles. J. Biomechanics 1984; 17:923-935

8.

B. Drerup. Improvements in measuring vertebral rotation from the projection of the pedicles. J. Biomechanics 1985;18:369-378

9.

B. Drerup, E. Hierholzer. Evaluation of frontal radiographs of scoliotic spines-Part 1: Measurement of position and orientation of vertebrae and assessment of clinical shape parameters. J. Biomechanics 1992; 25:1357-1362

10. B. Drerup, E. Hierholzer. Evaluation of frontal radiographs of scoliotic spines-Part 2: Relations between lateral deviation, lateral tilt, axial rotation of vertebrae. J. Biomechanics 1992; 25:1443-1450 11. B. Drerup, E. Hierholzer. Description of scoliotic deformity by modulated sinusoidal functions. Threedimensional Analysis of Spinal Deformities (ed. by D'Amico M, Merolli A, Santambrogio GC), IOS Press/Omsha Amsterdam/Tokyo 1995; 113-118 12. E. Hierholzer, L. Hackenberg. Three-dimensional shape analysis of the scoliotic spine using MR tomography and rasterstereography (this volume)

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Spine-rib Rotation Differences at the Apex in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS): Evaluation of a Three-Level Ultrasound Method R. G. Burwell1, R. K. Aujla 1 , A. A. Cole1, A. S. Kirby1, R. K. Pratt1, J. K. Webb1 and A. Moulton2 1

The Centre for Spinal Studies and Surgery*, Queen's Medical Centre, Nottingham & 2 Department of Orthopaedic Surgery, King's Mill Hospital, Mansfield, England

Abstract. This paper evaluates a new real-time ultrasound method to assess the difference between axial spinal (laminal) rotation and rib rotation at the apex of the scoliosis curve. An Aloka SSD 500 portable ultrasound machine with a veterinary long (172mm) 3.5 MHz linear array transducer was used to assess the reproducibility of the method in 13 preoperative patients with AIS. With the subject in a prone position and her head supported, readings of laminal and rib rotation were made directly on the back at 18 and 12 levels respectively The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). All the readings were made by one observer (ASK). After plotting on graphs three levels of maximal difference between spine rotation and rib rotation about the apex were chosen visually by one observer (RGB) for which the mean apical spine-m/nwj-rib rotation difference (SRRD) was calculated for each repeat. Findings for apical SRRDs. The mean apical SRRDs for the two repeats are 7.1 degrees and 6.9 degrees (range 2-18 degrees) with coefficients of variation of 49% and 62% respectively. Reproducibility. Graphic representation of spinal and rib rotation by 12 levels shows a fairly good agreement between repeats for most subjects. Spinal rotation is always greater than rib rotation. A paired t-test for the mean apical SRRD of the repeats shows no significant difference. Linear regression analysis of the mean apical SRRD repeats correlate significantly (r=0.70, P=0.008) with a residual mean square of 6.9 degrees (rms - 2.6 degrees). The technical error of the measurement (TEM) is 2.3 degrees and coefficient of reliability (R) 0.66. Conclusions. Real-time ultrasound can assess the difference between spinal and rib rotation about the apex of the scoliosis curve without the altered position detectably affecting the findings. The error (2-3 degrees) is high relative the mean apical SRRD (6-7 degrees). The apical SRRD findings have relevance to the pathogenesis of AIS. "Supported by AO/ASIF Research Commission Project 96-W21

1. Introduction The rib deformities of structural scoliosis are generally thought to be an adaptation to forces imposed by the scoliotic spine [10]. In contrast, Sevastik [6] has adduced experimental, anatomical and clinical evidence that asymmetrical rib growth is the primary factor in the pathogenesis of right thoracic AIS in girls. In his view asymmetrical rib growth disturbs the equilibrium of the forces that determine the normal alignment of the thoracic spine and triggers the thoracospinal deformity of scoliosis

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simultaneously in three planes. Sevastik's theory does not deal with the factors involved in the progression of the curve which he considers to be of a biomechanical nature [6,7]. In view of these conflicting views for the role of the ribs in the pathogenesis of AIS pathogenesis the relation of axial spinal rotation to rib rotation is of importance. Stokes [8] in a stereoradiographic study of 40 patients with idiopathic scoliosis found that vertebral rotation was generally greater than rib rotation. This was confirmed in an ultrasound study of 20 scoliosis school screening referrals by Kirby et al [4]. In the latter study summated ultrasound spinal (laminal) rotation from Tl-12 correlated significantly with summated ultrasound rib rotation (r=0.83, PO.001) with spinal rotation being greater than rib rotation. This paper uses a real-time ultrasound method to evaluate the rib rotation in relation to spinal rotation about the apex of the curve in preoperative patients with AIS. 2. Material and Methods 2.1 The patients and their spinal curves After informed consent from the parents/guardians 13 preoperative patients were included in the study (10 girls and 3 boys, mean age 15.4 years). The spinal curves were thoracic 7, thoracolumbar 6 with a mean Cobb angle of 50 degrees, right 9, left 4. The patients are those in each of the Scoliometer and ultrasound studies reported elsewhere in this volume [2,3]. 2.2 The prone position for the ultrasound spinal and rib rotation readings In the prone position the patient lies on a hard couch with her forehead supported on a stand, the arms dependent and the anterior superior iliac spines in contact with the couch. The transducer is aligned with the laminae or ribs to produce a horizontal image on the display monitor and readings made directly from the Scoliometer attached to the probe [3,4]. 2.3 The portable ultrasound machine The ultrasound equipment included an Aloka SSD 500 portable machine with a 3.5 MHZ wide field of view (172 mm) linear array transducer. A commercial Scoliometer was positioned on the transducer and used to read the angles of inclination relative to the horizontal to the nearest 0.5 degrees for each of the laminae and ribs at each level. 2.4 Repositioning the patient between scans The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). All the readings were made by one observer (ASK). 2.5 Right rotations are assigned positive values and left rotations negative values To plot the data 12-level right spinal and rib rotations were assigned positive values and left rotations negative values [3].

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2.6 The three levels of maximal difference between spine rotation and rib rotation are chosen The maximal SRRDs are observed to be about the apex of the scoliosis curve. One observer (RGB) chose three levels of maximal difference between spine rotation and rib rotation on the two graphs for each patient (i.e. the first and second repeats). The mean of the spine-mmi/5-rib rotation difference (SRRD) at these three levels was calculated for each patient in each repeat. The SRRD data were calculated as each of (1) positive sign to the right and a negative sign to the left (without correction for side), and (2) as positive values (with correction for side). 2.7 Summated and averaged SRRDs In calculating the mean apical spine rib-rotation difference (SRRD) and the coefficient of variation the SRRDs on the left were made positive (i.e.correction for side). In the paired t-test analysis data that had been corrected for side and not corrected for side were used. 2.8 Statistical analyses The mean and standard deviation of the three-level apical SRRDs for the repeats in each of the patients were calculated including the coefficient of variation (standard deviation/mean x 100). The mean SRRDs were analysed for reproducibility using a paired t-test, correlation coefficient, linear regression analysis, analysis of variance to calculate the residual mean square, technical error of the measurement (TEM) and coefficient of reliability (R) [9]. 3. Results 3.1 Mean apical spine rib-rotation difference (SRRD) and coefficient of variation. The mean SRRDs for the repeats are 7.1 degrees and 6.9 degrees (range 2-18 degrees). The coefficient of variation for the repeats are 3.5/7.1 = 49%, and 4.3/6.9 = 62%. 3.2 Reproducibility of repeats 3.1.1 Graphic representation of SRRDs by 12 levels shows a fairly good agreement between repeats for most patients. 3.1.2 Paired t-tests for the mean apical SRRD between repeats show no statistically significant difference (with and without correction for side). 3.1.3 Linear regression analysis of the mean apical SRRDs for the repeats correlate highly significantly (r = 0.70, P = 0.008, with correction for side). 3.1.4 The residual mean square of the mean apical SRRDs for the repeats is 6.9 degrees (root mean square, rms = ± 2.6 degrees, with correction for side). 3.1.5 The TEM is 2.3 degrees (with correction for side). 3.1.6 The coefficient of reliability is 0.66 (with correction for side).

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4. Discussion 4.1 Axial rotation and deformities of the ribs at the apex Wever et al [10] found that the ribs on the convex side show an increase of the rib curvature at the posterior angle. The concave ribs are flattened at the posterior angle. Hence the rib 'rotation' measured by ultrasound at the apex also includes deformity of the ribs [8]. 4.2 The method of measuring apical SRRD Unlike the positional difference for the separate measurement of each of spinal (laminal) rotation and rib rotation [3] there is no detectable positional variation of SRRDs. This supports the view that in prone lying the spine and the ribs move together about the apex. 4.3 The SRRD at the scoliosis curve apex The axial spinal rotation is greater than the axial rib rotation about the apex in these preoperative patients with AIS. The mean difference is 6-7 degrees with a standard deviation of ±3.5 to ±4.3 degrees (range 2-18 degrees). The coefficient of variation of the SRRDs is 49-62%. 4.4 The SRRD above and below the scoliosis curve apex The findings for the SRRDs above and below the curve apex are not reported in this paper. They are markedly less than about the apex of the curves. 4.5 Relation to pathogenesis of AIS The finding that the spine (laminae) are more axially rotated than are the ribs about the curve apex is consistent with the view that in AIS the axial rib rotation and rib deformities are each an adaptation to forces imposed by the scoliotic spine [10]. But it is plausible that asymmetrical rib growth triggers the thoracospinal deformity of scoliosis and the apical vertebrae then deform due to biomechanical factors [6,7]. In recent years others have argued that the ribcage is involved in the pathogenesis of AIS [1,5] The mean Cobb angle hi these patients was 50 degrees so it is possible that in smaller curves the axial spinal rotation would not be greater than the axial rib rotation. In an ultrasound study of school screening referrals with a mean Cobb angle of 19 degrees [4] spinal (laminal) rotation at Tl-12 was found to be generally greater than rib rotation. But the three-level mean apical SRRD method was not employed. Hence further work is needed to evaluate apical SRRDs in smaller scoliosis curves and particularly the change in SRRDs with curve progression during follow-up. References 1.

R.G. Burwell et al., Pathogenesis of idiopathic scoliosis: the Nottingham concept. Acta Orthopaedica Belgica 58: Supplement 1, pp 33-58, 1992. 2. R.G.Burwell et al., Back shape assessment in each of three positions in preoperative patients with adolescent idiopathic scoliosis (AIS): evaluation of a 10-level Scoiiometer method interpolated to 18-levels. In, Research into Spinal Deformities 4. T B Grivas (ed.). pp xx, Amsterdam:IOS Press, 2002. 3. R.G.Burwell et al., Preliminary study of a new real-time ultrasound method for measuring spinal and rib rotation in preoperative patients with adolescent idiopathic scoliosis. In, Research into Spinal Deformities 4. T B Grivas (ed.). pp xx. Amsterdam:IOS Press, 2002.

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5.

6. 7. 8.

A.S. Kirby et al., Evaluation of a new real-time ultrasound method for measuring segmental rotation of vertebrae and ribs in scolisois. In, Research into Spinal Deformities 2.1.A.F. Stokes (ed.), pp 316-320, Amsterdam:IOS Press, 1999. T.B. Grivas et al.. The double rib contour sign (DRCS) in lateral spinal radiographs: aetiologic implications for scoliosis. In, Research into Spinal Deformities 3. A. Tanguy, B. Peuchot (eds.), Amsterdam:IOS Press, 2002. J.A. Sevastik. The thoracospinal concept of the etiopathogenesis of idiopathic scoliosis. In, Spine: State of the Art Reviews 14(2):391-400,2000. J.A. Sevastik. A new concept for the etiopathogenesis of the thoracospinal deformity of idiopathic scoliosis (IS). European Spine Journal. In Press. I.A.F Stokes. Axial rotation component of thoracic scoliosis. Journal of Orthopaedic Research 7: 702-708, 1989.

9. S.J. Ulijaszek, J.A. Lourie, Intra- and inter-observer error in anthropometric measurement. In, Anthropometry: the individual and the population. S.J. Ulijazek, C.G.N. MascieTaylor (eds.), Chapter 3, pp. 30-55, Cambridge University Press, 1994. 10. D.J Wever et al., A biomechanical analysis of the vertebral and rib deformities in structural scoliosis. European Spine Journal 8:252-260, 1999.

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Sagittal and transversal plane deformity in thoracic scoliosis Tomasz Kotwicki, M.D. Department ofPaediatric Orthopaedics University of Medical Sciences ul. 28 Czenvca 1956 roku nr 135 61-545 Pozna, Poland tomaszkotwicki@poczta. onet.pl [email protected] Abstract. The aim of the study was to assess the sagittal and transversal plane deformity of the spine in thoracic scoliosis by the mean of 3-D radiographic analysis. 46 patients admitted for surgery for thoracic idiopathic scoliosis underwent preoperative radiographic assessment. All patients presented the same pattern of the coronal plane deformity: single right thoracic curve (Lenke 1, King 3). Neither lumbar nor proximal thoracic structural curve were present. The Cobb angle varied from 41T to 77 F (mean 55,4 F ± 8,6 F). Long cassette standing antero-posterior and lateral radiographs were analysed. Threedimensional reconstruction with Rachis 91TM software was performed for each pair of radiographs. The following parameters were assessed: sagittal thoracic Cobb angle (Th4-Thl2), upper thoracic kyphosis angle (Th5-Th8), lower thoracic kyphosis angle (Th9-Thl2), superior and inferior hemi-curve sagittal angles, lumbar lordosis, sacral slope, sacral incidence, vertebral plate index, segmental vertebral axial rotation throughout the thoracic and lumbar spine. Results showed great variability of parameters assessed. The non-harmonious distribution of kyphosis was demonstrated in the thoracic spine. Local Th9Thl2 hypokyphosis and adjacent local Th5-Th8 hyperkyphosis constitute the most typical sagittal pathologies. So called normokyphotic curves were composed of one hyperkyphotic and one hypokyphotic zone. Thl-Th4 segment revealed two patterns of segmental rotation distribution: a purely compensatory curve with no vertebral axial rotation or a rotated curve presenting the morphology intermediate between Lenke 1 and Lenke 2 types (or King 3 and King 5). In conclusion: curves presenting the same coronal plane deformity differ in their morphology assessed in the two other planes; global thoracic kyphosis angle is a misleading parameter because it covers hypo- and hyperkyphotic zones; local distal thoracic (Th9-Thl2) hypokyphosis is present in idiopathic thoracic scoliosis.

1. Introduction The three-dimensional analysis of spinal deformity in idiopathic scoliosis requires data on sagittal and transversal plane deformity. It is not clear whether the curves similar in the coronal plane should present similar sagittal and transversal plane deformity. Physiological variability of sagittal curves is a factor complicating the sagittal plane assessment of the scoliotic spine. In normal subject the limits are used

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rather than the mean values [1] for the thoracic kyphosis angle and the lumbar lordosis angle. Sagittal thoracic Cobb angle has been accepted as one of the important parameters in the outcome of treatment of scoliosis. Recently Lenke et al. diffused a classification of scoliosis [6] and proposed the terms of normo- hypo- and hyperkyphotic curves according to sagittal Th5-Thl2 Cobb angle value. 2. Purpose of the work To analyse the sagittal and transversal plane deformity of scoliosis presenting the same coronal pattern of deformity - single structural thoracic curve. 3. Material and methods Forty-six patients admitted for surgery underwent preoperative radiological exam. They presented single right thoracic scoliosis. The apex of scoliosis was at Th8 or Th9 or the disc Th8/Th9. The upper limit vertebra was Th4 or Th5 or Th6 and the lower limit vertebra was Thl2 or LI. The Cobb angle varied from 41 ° to 77 ° (mean 55,4 ° ± 8,6 ° ; N=46). There were no structural curve in the lumbar spine nor in the upper thoracic Thl-Th4 segment. The criteria proposed by King [4] and by Lenke [6] were considered to rule out structural counter-curves. Long cassette standing antero-posterior and lateral radiographs were obtained for each patient. GP-9 digitizer of Science Accessories Corporation (U.S.A.) and RACHIS software (Hecquet-France) were used to obtain three-dimensional reconstruction of scoliotic spine. The lumbar spine sagittal plane was assessed by the lumbar lordosis angle (Thl 2Sl), the sacral slope angle and sacral incidence of Duval-Beaupere [5]. The thoracic spine sagittal plane was assessed by the standard sagittal Cobb angle, measured from the superior vertebral plate of Th4 to the inferior vertebral plate of Thl 2, curve containing 9 vertebrae. Moreover four other sagittal angles were measured: the upper thoracic angle between superior plate of Th5 and inferior plate of Th8 (4 vertebrae), the lower thoracic angle between superior plate of Th9 and inferior plate of Thl2 (4 vertebrae), the proximal hemi-curve angle between the superior plate of the superior limit

Fig. 1. Upper thoracic kyphosis angle Th5-Thl2 and lower thoracic kyphosis angle Th9Thl 2 (A). Superior and inferior hemi-curve sagittal Cobb angle, measured proximally and distally to the apical vertebra of thoracic scoliosis (B)

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vertebra of scoliosis and the superior plate of the apical vertebra of scoliosis (4 vertebrae on the average) and the distal hemicurve angle between the inferior plate of the apical vertebra of scoliosis and the inferior plate of the inferior limit vertebra of scoliosis (4 vertebrae on the average), (Fig. 1). Further analysis of sagittal thoracic Cobb angle (Th4-Thl2) consisted on identification of "normokyphotic" curves and "hypokyphotic" curves using 20 degrees of kyphosis as inferior limit of normal range of kyphosis according to Bridwell et al. [2]. This division of curves into "normo-" and "hypokyphotic" was repeated using 10 degrees value as proposed by Lenke et al. [6]. Vertebral plate index was defined as a number of vertebral plates situated in kyphotic position each to other comparing with the number of lordotic vertebral plates. 2,4 was considered the normal value of vertebral plates index (24 thoracic plates / 10 lumbar plates). This parameter was considered sensitive for detection of presence of a lordotic segment at the thoracic level. For the transversal plane assessment the segmental vertebral axial rotation angle according to Perdriolle [7] was measured throughout the spine. 4. Results The results are given in table 1. Table 1. The values of measured parameters expressed as mean ± standard deviation; minimum and maximum values are indicated in the brackets. N=46. Positive values denote kyphosis and negative values denote lordosis. Lumbar lordosis (F) Sacral slope (F) Sacral incidence (F)

52,0 ±10,3 39,9 ±8,9 53,0 ±13,5

(28,4 + 74,6) (20,5 - 59,0) (24,8-91,0)

Sagittal thoracic Cobb angle Th4-Th 12 (F)

16,5 ± 13,7

(-23,9 - 39,9)

Upper thoracic kyphosis angle Th5-Th8 (F) Lower thoracic kyphosis angle Th9-Th 12 (F)

15,8 ± 8,8 3,9 ± 8,0

(-1,5- 38,2) (-19,9 - 21,5)

Superior hemi-curve sagittal angle (F) Inferior hemi-curve sagittal angle (F)

11,6 ±7,7 1,0 ± 7,8

(-1,5-38,2) (-19,2 - 15,8)

1.6 ±0,7

(0,4 + 3,0)

Vertebral plates index

Twenty-six "hypokyphotic" curves and 20 "normokyphotic" curves were found when the criterion of Bridwell et al. of the 20° sagittal Th5-Thl2 Cobb angle was used. Analysis of Th9-Thl2 sagittal kyphosis angle revealed that 11 of 20 "normokyphotic"

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curves were in fact hypokyphotic in the Th9-Thl2 segment. Only 9 curves could be considered truly normokyphotic. When the value of 10° of Th5-Thl2 kyphosis was considered a normal limit, as proposed by Lenke et al. [6], 17 curves were "hypokyphotic" and 29 were "normokyphotic". The additional 9 "normokyphotic" curves were analysed for segmental distribution of kyphosis. Seven of these nine presented hypokyphosis or lordosis in the Th9-Thl2 segment. Only the two remaining curves of nine could be considered normokyphotic. No "hyperkyphotic" curves were identified (>40 ° according to Lenke et al.). Segmental vertebral axial rotation is given in figure 2. The analysis of vertebral axial rotation in non-structural, compensatory curves revealed a difference between left lumbar curve and left upper thoracic curve. The former consisted of vertebrae of negligible axial rotation, inferior to 5° according to Perdriolle method in 41 cases. In the remaining 5 cases the rotation of apical L3 vertebra exceeded 5°. The vertebral axial rotation throughout the left upper thoracic compensatory curve was much more important. It was superior to 5° in 25 cases, inferior to 5° in 15 curves and of 0° in the remaining 6 curves.

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5. Discussion Lumbo-sacral spine parameters: the angle of lumbar lordosis, of sacral slope and angle of incidence did not differ from the normal values. This can be related to the fact that the lumbar spine presented non-structural compensatory curve. Pelvic morphology, expressed by sacral incidence did not seem to be altered in the presence of thoracic scoliosis. The angle of lumbar lordosis was measured from the inferior plate of Th 12 to the superior plate of SI. This is why it was slightly higher than that reported by Bridwell et al. [2]. It was clearly demonstrated that the sagittal thoracic Cobb angle, measured from Th5 to Thl2 can be misleading. In fact this area is often composed of hypo-, normo- and hyperkyphotic zones. The global angle may be within the normal limits while the thoracic sagittal curvature may be pathological. This pathology is difficult to quantify and it can be described as non-harmonious distribution of segmental sagittal angulation of vertebrae. Local Th9-Thl2 hypokyphosis was constantly seen. It was confirmed by the low value of vertebral plate index. The lumbar lordosis prolonged proximally into the thoracic spine. Lower thoracic kyphosis angle was significantly inferior to the upper thoracic kyphosis angle. The inferior hemicurve kyphosis angle was significantly lower to the superior hemicurve angle. Both lower thoracic kyphosis angle and the inferior hemicurve kyphosis angle differ from the normal limits predicted by Bernhardt and Bridwell [1]. On the other hand in the thoracic spine above the apex of scoliosis the sagittal Cobb angle was within normal limits or increased. The interpretation could be that lordotic segment is balanced by a kyphotic one (figure 3). The global Th5-Thl2 angle refers only the relation between these two vertebrae and does not take into account the variation of kyphosis within the long segment of nine vertebrae. "Normokyphotic" curves revealed important disturbation of sagittal alignment. This should be considered in the assessment of correction of scoliosis.

"normal" global thoracic kyphosis

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77 Fig.3. Global thoracic kyphosis is composed of normo-, hypo- and hyperkyphotic zones.

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Heterogeneity of sagittal profile was found at radiographs. May it be attributed to normal variation of sagittal shape of the spine or does it signify different pathomechanisms of development of these curves? The latter seems less probable [3]. Obviously the analysed curves did not represent the same 3-D deformity even if the coronal plane deformity was very similar. The transversal plane analysis was limited to the vertebral axial rotation angle. Specially the compensatory curves were considered. Axial rotation in upper thoracic counter-curve was superior to that of lumbar counter-curve. In fact it seems that a group of scoliosis of morphology intermediate between Lenke 1 and 2 (or King 3 and 5) types exists. The clinical significance of 3-D detailed analysis may consist in the proper definition of the corrective movement of each particular scoliosis. 6. Conclusions 1. The curves of the same pattern in the frontal plane present heterogeneous deformity in the sagittal and transversal plane. 2. The sagittal thoracic Cobb angle can be misleading when measured between Th4 and Thl2 or between Th5 and Thl2. Inside this area there can exist zones composed of a few vertebrae that largely differ each from other for the sagittal Cobb angle. 3. The local hypokyphosis in the inferior thoracic spine, usually between Th9 and Th 12 was most constantly observed in idiopathic single thoracic scoliosis. References 1 2 3 4 5 6 7

Bemhardt M, Br idwell KJH: Segmental analysis of the sagittal plane alignment of the normal thoracic and lumbar spines and thoracolumbar junction. Spine 1989; 14: 717-21. Bridwell KH, Betz RR, Capelli AM et al.: Sagittal plane analysis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation. Spine 1990; 15: 921-6. Dubousset J.: Three-dimensional analysis of the scoliotic deformity. In: The Pediatric Spine, red. Weinstein S. L,, Raven Press, New York, 1994:479-496. King H. A., Moe J. H., Bradford D. S., Winter R. B.: The selection of fusion level in thoracic idiopathic scoliosis. J. Bone Joint Surg., 1983; 6S-A: 1302-1313. Legaye J, Duval-Beaupere G, Hecquet J, Marty C.: Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J 1998; 7: 99-103. Lenke LL, Betz RR, Haher TR et al. : Multisurgeon assessment of surgical decision-making in adolescent idiopathic scoliosis. Curve classification, operative approach and fusion levels. Spine 2001:26:2347-53. Perdriolle R.: La scoliose. Son etude tridimensionnelle. Maloine S. A. Editeur, Paris, 1979.

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A new X-ray calibration / reconstruction system for 3D clinical assessment of spinal deformities F. Cheriet, Ph.D.12; L. Remaki, Ph.D.1'2; C. Bellefleur, M.Sc.A.2; A. Roller, B.Sc.2; H. Labelle, M.D.2, J. Dansereau, Ph.D.1 2 1

Ecole Polytechnique de Montreal, P.O. box 6079, succursale Centre-Ville, Montreal, Quebec, Canada, H3C 3A7. 2 Sainte-Justine Hospital Research Centre, 3175 Cote-Sainte-Catherine road, Montreal, Quebec, Canada, H3T1C5 Abstract. The main objective of this study was to develop a 3D X-ray reconstruction system of the spine and rib cage for an accurate clinical assessment of spinal deformities. The proposed system uses an explicit calibration technique and a new calibration object composed of: (1) a set of radiopaque markers embedded in a jacket worn by the patient during the X-ray exposures; (2) six control markers to define a reference vertical plane. Computer simulations were performed to evaluate the accuracy of the 3D reconstruction procedure when different kind of displacements were applied on a reference model. Clinical indices computed from the 3D X-ray reconstruction of the spine for 24 scoliotic subjects were compared to those obtained with the DLT method. The results of the evaluation study showed that the new system allows the patient to adopt a normal attitude without any constraint, compensating for its displacement between exposures.

1. Introduction The three-dimensional reconstruction system of the spine and rib cage from multiview X-rays is a prerequisite for an adequate 3D evaluation of spinal deformities. The system currently used at Sainte Justine Hospital is based on an implicit calibration technique (DLT), using a sufficiently large object rigidly incorporated in the positioning apparatus to position any anatomical structure to be reconstructed inside its limits. The calibration object is made of two acrylic sheets located on both sides of the patient, with 55 embedded radio-opaque steel balls (2-3 mm in diameter) measured in 3D. The 3Dreconstruction method developed by Dansereau et al. [1] consists in computing the linear relation between the measured 3D and 2D image coordinates of the steel balls. Afterwards, this relation is applied on the 2D coordinates of matched anatomical landmarks in order to obtain the 3D coordinates of the bone structure. However, during the time involved between two X-ray exposures, involuntary movements of the patient introduce 3D reconstruction errors due to the linear relation inferred from the rigid

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F. Chcricl ct ul. / -\ AVu X-Rtiy Culihmtion /Reconstruction System

calibration object. Marcil et al.[2] developed a method for 3D reconstruction of the rib cage by taking into account patient displacement during stereoradiography. Unfortunately, the movements of the patients consist of a combination of respiration, lateral translation and lateral inflexion, which result in complex distortions that are not easy to compensate on the 2D X-rays. The objective of this study was twofold: first, to design a new calibration object composed of a set of radio-opaque markers embedded in a jacket worn by the patient during X-ray exposures. Therefore, the new calibration object undergoes the same displacement as the patient between X-ray exposures, which allows the calibration algorithm to compensate this displacement. Second, develop a new calibration algorithm, based on a non linear optimization process, to avoid the extrapolation errors that may occur with linear approaches (DLT) when the calibration object is not sufficiently large to position any anatomical structure to be reconstructed inside its limits. 2. Materials and Methods Two postero-anterior radiographs (the standard PA-0° and the twenty degrees angled down PA-200) and one lateral radiograph are acquired from the radiographic setup shown in Fig. 1 for the 3D reconstruction of the spine, rib cage and pelvis. The positioning apparatus allows a 90° rotation by means of a turntable to bring the patient from lateral to the PA position. The patient stabilization devices retained for the new positioning apparatus were elbow supports with handlebars.

Fig. 1. The radiographic setup used for the standard views, (a) PA-0° view, (b) PA-200 view, (c) lateral view.

The new calibration object (see Fig. 2) was composed of two parts: a jacket with 12 embedded radio-opaque markers worn by the patient during exposures; an acrylic sheet with 6 radio-opaque steel balls (2-3 mm in diameter) embedded in it and measured

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at a high precision with a CMM (Computerized Measuring Machine). The 12 markers embedded in the calibration jacket were detected and matched on a pair of X-rays. Then, their 2D coordinates were used to compute the epipolar geometry which describe the relative orientation between the two views by taking into account the displacement of the patient between the two views. The 6 radio-opaque steel balls were used to define a reference vertical plane of the global coordinate system.

Fig.2. The new calibration object The calibration algorithm estimates the optimal geometrical parameters that describe the radiographic setup used to acquire the pair of X-rays. The method used for this purpose is based on the explicit calibration algorithm described by Cheriet et al.[3]. An iterative method was used to minimize the mean square distance between the observed projection of the jacket calibration markers of unknown 3D coordinates and their analytic projections. The reference vertical plane was included in the minimization process as an additional constraint in order to obtain the 3D reconstruction of the bone structure in the global coordinate system. Simulations were performed to evaluate the robustness of the calibration algorithm under realistic clinical conditions, where a displacement of the patient can occur between the X-ray exposures. The image acquisition process was simulated using a 3D model of the human trunk obtained by performing a radiographic 3D reconstruction of an X-ray dummy using the DLT technique. Radio-opaque markers were placed on the external surface of the dummy to simulate the calibration jacket. To simulate the acquisition process, two typical sets of geometrical parameters (one for each view), describing the routinely used radiographic setup, were used to compute analytic perspective projections of the 3D model. For each simulation, an analytic PA-0° projection of the 3D model, markers of the calibration jacket and the reference plane was

260

F. Cheriet a al. /A /\Vu X-Ra\ Culihrtilion / Rci'onstnictitm S\.\lem

first computed. To simulate patient displacement between the X-ray exposures, the 3D model and markers were then transformed, before they were analytically projected on the lateral view. The system was then calibrated using the calibration method described in [3]. A 3D reconstruction of the anatomical structures was then performed and the RMS distance error between the 3D reconstructed coordinates and the 3D model coordinates was computed. Three common types of patient displacement were taken into account in this study: balance in frontal plane, balance in the sagittal plane and shoulder rotation in the coronal plane. Clinical indices computed from the 3D X-ray reconstruction of the spine for 24 scoliotic subjects were compared to those obtained with the DLT method. 3. Results and discussion A 3D reconstruction RMS error of 3.1 ± 0.9 mm was obtained even if a displacement of 10 degrees was introduced to simulate respectively the balance in frontal plane, the balance in the saggital plane and the shoulder rotation in the coronal plane. This kind of displacement is widely greater than the real patient displacement measured in the new positioning apparatus [4]. Several clinical geometrical indices described in [5] were computed from both the new reconstruction method and the standard method based on the DLT technique. The mean difference and the standard deviation obtained for 24 scoliotic patients are summarized in Table. 1. Table 1; Difference in clinical geometrical indices computed from the new and DLT methods Geometrical indices N Mean (degrees) Standard deviation (degrees) Cobb angle in sagittal plane Cobb angle in frontal plane Cobb angle in the plane of maximum deformity Orientation of the plane of maximum deformity Kyphosis Lordosis

66 75 75 75 24 24

-0.3

0.0 -0.3

1.6 0.2 -0.5

1.4 1.5 1.8 3.1 1.4 2.2

The preliminary results are very promising but more patients will be included in this clinical study as well as other geometrical indices to perform an adequate statistical analysis in order to validate the accuracy of the new system. 4. Conclusion The new system provides to the clinician an accurate tool to evaluate spinal deformities and allows the patient to adopt a normal attitude without any constraint, compensating for its displacement between exposures. The validation study is still underway to further evaluate the accuracy of the new method and correlate the clinical indices calculated from the new method to those calculated from the standard method based on the DLT technique. Finally we believe that the proposed approach will be useful and less restrictive than the standard calibration technique since it should be adapted to evaluate 3D deformities

/•". Chcrict ft a/. /A /Vc-n X-Rd\ Ctil/hnition / Kccon\inictit>n System

26

of patients confined to a wheelchair and patients lying down in prone position during a surgical procedure, which was not possible with previous techniques requiring a large calibration object. Acknowledgments This work was supported by the Natural Sciences and Engineering Research Council of Canada.

References 1. J. Dansereau et al., Three dimensional reconstruction of the spin and rib cage from stereoradiography and imaging techniques, Procedings ofSociete Canadienne de Genie Mecanique, 2 (1990): 61-64 2. E. Marcil et al., Improvement of rib cage 3-D reconstruction by taking into account patient displacement during stereoradiography. IOS Press, Pescara, 1994. 3. F. Cheriet et al., Towards the Self-Calibration of a Multi-view Radiographic Imaging System for the 3D Reconstruction of the Human Spine and Rib Cage, International Journal of Pattern Recognition and Artificial Intelligence 13 (1999) 5: 761-779. 4. C. Bellefleur et al., Evaluation of the efficiency of patient stabilisation devices for 3D X-ray reconstruction of the spine and rib cage. IOS Press, Clermont Perrand, 2000. 5. H. Labelle et al., Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages. Eur. Spine Journal 4 (2) (1995) 88-94.

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Preliminary Study of a New Real-time Ultrasound Method for Measuring Spinal and Rib Rotation in Preoperative Patients with Adolescent Idiopathic Scoliosis (AIS) R. G. Burwell1, R. K. Aujla1, A. A. Cole1, A. S. Kirby1, R. K. Pratt1, J. K. Webb1 and A. Moulton2 l

The Centre for Spinal Studies and Surgery*, Queen's Medical Centre, Nottingham & 2 Department of Orthopaedic Surgery, King's Mill Hospital, Mansfield, England

Abstract. A portable ultrasound machine with a linear array transducer was used by one observer (ASK) to evaluate the reproducibility for each of spinal (laminal) rotation and rib rotation in 13 preoperative patients with AIS (thoracic 7, thoracolumbar 6, mean Cobb angle 50 degrees, right 9, left 4, age 15.4 years, girls 10). With the subject in a prone position and her head supported, readings of spinal (laminal) and rib rotations were made directly on the back at 18 and 12 levels respectively. The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). Conclusious. Repositioning the patient significantly alters some single level readings of lam inal rotation and rib rotation. Although the mean average spinal rotation and rib rotation each have acceptable reproducibility, repositioning the patient significantly alters the findings. In the appraisal of surgery by ultrasound [3] the positional change reported here for (I) single level laminal rotation and rib rotation, and (2) mean average rotation imposes caution on the interpretation of the findings. The method enables the axial spine-nh rotation differences to be evaluated which is the subject of a separate paper [2]. #Supported by AO/ASIF Research Commission Project 96-W21 1. Introduction A feasibility study [4] at five sites in the back (T4, T8, T12, L3, S2) of school screening referrals (n= 8) showed that real-time ultrasound could be used to measure axial spinal (laminal) rotation and rib rotation in a prone position. Subsequently [5] the method was evaluated in 20 school screening referrals (mean Cobb angle 19 degrees) which showed that ultrasound laminal rotation (at 18 levels T1-S1) can be measured to within ±3.1 degrees and ultrasound rib rotation to within + 2.8 degrees (95% confidence limits). The data for each patient, plotted segmentally, revealed the axial rotational deformity in

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each of the vertebrae and the ribs. This paper reports the use of real-time ultrasound to evaluate the reproducibility of laminal and rib rotation in 13 preoperative patients with adolescent idiopathic scoliosis (AIS) in a prone position. 2. Material and Methods 2.1 The patients and their spinal curves After informed consent from the parents/guardians 13 preoperative patients were included in the study (10 girls and 3 boys, mean age 15.4 years). The spinal curves were thoracic 7, thoracolumbar 6 with a mean Cobb angle of 50 degrees, right 9, left 4. The patients are those in the Scoliometer study reported elsewhere in this volume [1]. 2.2 The prone position for the ultrasound spinal and rib rotation readings In the prone position the patient lies on a hard couch with her forehead supported on a stand, the arms dependent and the anterior superior iliac spines in contact with the couch. The transducer is aligned with the laminae or ribs to produce a horizontal image on the display monitor and readings made directly from the Scoliometer attached to the probe [4,5]. 2.3 The portable ultrasound machine The ultrasound equipment included an Aloka SSD 500 portable machine with a 3.5 MHZ wide field of view (172 mm) linear array transducer. A commercial Seoliometer was positioned on the transducer and used to read the angles of inclination relative to the horizontal to the nearest 0.5 degrees for each of the laminae and ribs at each level. 2.4 Repositioning the patient between scans The subject was repositioned after walking around the room and a second set of scans obtained (repeats). All the readings were made by one observer (ASK). 2.5 Right spinal and rib rotations are assigned positive values and left spinal and rib rotations negative values

In plotting the ultrasound rotation data to provide a graphic representation right rotations are assigned positive values and left rotations negative values (-- sign for side). 2.6 Mean ATJs at each level

A paired t-test was performed at each level without correcting the sign for side. 2.7 Summated and averaged A TIs without and with correction for side In the reproducibilty analyses for the repeats the sign for side was not corrected unless stated. To provide an overall descriptor of back shape the spinal rotations (18 levels) and rib

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rotations (12 levels) of each patient were made positive (i.e. corrected for side), summated and averaged to calculate mean average rotations (and standard deviations). 2.8 Statistical analyses The 18-level laminal rotations and 12-level rib rotations were each analysed for reproducibility. The statistical analyses included a paired t-test, correlation coefficient, linear regression analysis with ANOVA to produce the residual mean square (and root mean square, rms) relative to the regression line, technical error of the measurement (TEM) and coefficient of reliability, R., TEM is calculated as the square root of (the difference between ATI measurements squared/2 x number of patients measured) [6]. R is calculated as 1 [TEM)2/(SD)2] where SD is the total inter-patient variance, including measurement error for the ATIs [6]. 3. Results 3.1 Ultrasound spinal (lam inal) rotations 3.1.1 The mean average lam inal rotation for 18 levels of the 13 patients is 6.4 degrees (with correction for side, first repeat). 3.1.2 Graphic representation of laminal rotations by 18 levels shows a fairly good agreement between repeats for most patients. 3.1.3 A paired t-test at each of 1 8 levels between repeats shows a statistically significant difference only at Tl 1 (Bonferroni correction). 3.1.4 A paired t-test on the mean average spinal rotations between repeats shows a significant difference (with and without correction for side, each P<0.05). 3.1.5 Linear regression analysis of the mean average spinal rotations for the repeats correlate very highly significantly (r--0.96, PO.001). 3.1.6 Residual mean square of the mean average spinal rotations between repeats is 2.1 degrees (root mean square, rms 11.4 degrees). 3.1.7 The TEM is 1.6 degrees. 3.1.8 The coefficient of reliability (K) is 0.88. 3.2 Ultrasound rib rotations 3.2.1 The mean average rib rotation for 12 levels of the 13 patients is 4.8 degrees (with correction for side, first repeat). 3.2.2 Graphic representation of rib rotations by 12 levels shows a fairly good agreement between repeats for most patients. 3.2.3 A paired t-test at each of 12 levels between repeats shows a statistically significant difference at two levels (Bonferroni correction). 3.2.4 A paired t-test on the mean average rib rotations between repeats shows a significant difference (with and without correction for side, P—0.002, P=0.01 respectively). 3.2.5 Linear regression analysis of the mean average rib rotations for the repeats correlate very highly significantly y~0.96, P<0.001). 3.2.6 Residual mean square of the mean average rib rotations for the repeats is 1.4 degrees (root mean square, rms 11.2 degrees). 3.2.7 The TEM is 1.4 degrees. 3.2.8 The coefficient ofreliabiliiy (R) is 0.88.

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4. Discussion 4.1 Reproducibility

A difficulty of the method was always locating the same lamina, or rib, in both of the repeats for each subject. The use of the mean average summation of spinal rotations (for 18 levels) and rib rotation (for 12 levels) overcame this problem. It also provided an overall descriptor of spinal and rib rotations with correction for side, which was used for reproducibility analyses with and without correction for side. The reproducibility of the mean average rotations expressed as root mean square (rms) is for spinal (laminal) rotation 11.4 degrees and rib rotation 11.2 degrees. These findings show an acceptable reproducibilty. It is similar to the reproducibility of using the Scoliometer to measure angle of trunk inclinations (ATIs) in each of the standing forward-bending and prone positions (rms -1 .3 degrees, 1.4 degrees) and better than in the sitting forward-bending position (rms 1 2.3 degrees) [1]. The reproducibility of the mean average rotations expressed as TEMis for spinal (laminal) rotation 1.6 degrees and rib rotation 1.4 degrees. It is not as good as the reproducibility of using the Scoliometer to measure ATIs in the standing forwardbending position (1.1 degrees), is similar to that in the prone position (1.5 degrees respectively) but better than in the sitting forward-bending position (1.8 degrees) [1]. The reproducibility of the mean average rotations expressed as coefficient of reliability is for spinal (laminal) rotation 0.88 and rib rotation 0.88. It is not as good as the reproducibility of using the Scoliometer to measure ATIs in the standing forward-bending position (0.96), is similar to that in the prone positions (0.90) but better than in the sitting forward-bending position (0.82) [1]. 4.2 The prone position and the problem of repositioning. Repositioning the patient significantly alters one or more single level readings of laminal rotation (one level) and rib rotation (two levels). In view of several levels being compared (18 and 12 levels respectively) this may be either a chance finding, or indicate that the method is accurate enough to detect positional change. Although the mean average laminal rotation and rib rotation each has acceptable reproducibility, repositioning the patient significantly alters the findings (3.1.4, 3.2.4). The Scoliometer ATI findings show a similar alteration in the prone position but only for two single levels and not for the mean average ATIs [11]. In the appraisal of surgery by ultrasound [3] the positional change reported here for (1) single level laminal rotation and rib rotation, and (2) mean average rotation imposes caution on the interpretation of the findings. 4.3 Ultrasound to measure axial spine-rib rotation differences Any alteration of the patients' position between repeats is likely to affect laminal

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rotation and rib rotation together. The method enables the axial spine-rib rotation differences to be evaluated which is the subject of a separate paper [2]. References 1

2

3

4

5

6

R.G.Burwell et aA, Back shape assessment in each of three positions in preoperative patients with adolescent idiopathic scoliosis (AIS): evaluation of a 10-level Scoliometer method interpolated to 18levels. In, Research into Spinal Deformities 4. T B Grivas (ed.), pp xx, Amsterdam:IOS Press, 2002. R.G Burwell et aA~ Spine-rib rotation differences at the apex in preoperative patients with adolescent idiopathic scoliosis: evaluation of a three-level ultrasound method. In, Research into Spinal Deformities 4. T B Grivas (ed.). pp xx, AmsterdamrlOS Press, 2002. R.G. Burwell et al., Anterior Universal Spine System (USS) for adolescent idiopathic scoliosis (AIS): a follow-up study using Scoliometer, real-time ultrasound and radiographs. Jn, Research into Spinal Deformities 4. T B Grivas (ed.). pp xx, Amsterdam:IOS Press, 2002 A.S. Kirby et aL, A preliminary study of a new real-time ultrasound method for measuring rib rotation and spinal rotation in scoliosis. In, Research into Spinal Deformities 1. JA. Sevastik, K.M Diab (eds.). pp 335-337, Amsterdam:IOS Press, 1997. A.S. Kirby et aL, Evaluation of a new real-time ultrasound method for measuring segmental rotation of vertebrae and ribs in scolisois. In, Research into Spinal Deformities 2. I.A.F. Stokes (ed.), pp 316-320, Amsterdam:IOS Press, 1999. S.J. Ulijaszek, J.A. Lourie, Intra- and inter-observer error in anthropometric measurement. In, Anthropometry: the individual and the population. S.J. Ulijazek, C.G.N. Mascie-Taylor (eds.), Chapter 3,pp.30-55, Cambridge University Press, 1994.

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Geometric and postural analysis of mild idiopathic scoliotic patients N. Champuin 1 , R. Dupuis 1 , V. Pomero1, B. Mouilleseaux 2 , J. Dubousset \ W. Skalli ' Luhoratoire de BioMecanique, ENSAM-CNRS, Paris, France ~ Clinique de la Digonniere, Saint Etienne, France ' Hopital Saint Vincent de Paid, Paris, France

Abstract. Understanding the aggravation process of mild idiopathic scoliosis is still a challenge. The aim of this study is to investigate the spine and pelvis configuration with regard to gravity line using 3D reconstruction coupled with foot pressure measurements. The distance between each vertebral center and the gravity line is calculated in order to observe the global equilibrium of spine. A protocol has been set and used for 10 mild idiopathic scoliotic patients. 34 asymptomatic volunteers who were previously observed with the same protocol were used as reference for biomechanical comparisons. The first results showed differences between scoliotic and asymptomatic subjects and also among scoliotic patients. The proposed protocol should allow clinicians to follow up scoliotic patients with an innovative and efficient tool.

1. Introduction The evolution of mild idiopathic scoliotic patients is still difficult to predict. Duval Beaupere & al M proposed prognostic factors for mild scoliosis criteria to estimate cvolutivity (risk of progression). However there is still a need to complement proposed criteria to improve prognostic. Recent advances in 3D reconstruction of the spine and the pelvis 2 6 ' 7 8 '" allow clinicians to have a better understanding of the deformity. On the other hand, ground forces measurements provide information on location of the patients center of gravity related to postural balance 12 . The aim of this study is to propose a protocol for a coupled approach between 3D reconstruction and foot pressure measurement, which permits to have a localization of the gravity line (GL) of the patient with regards to spine and pelvis. 2. Material and methods 2.1 Clinical Data Ten mild idiopathic scoliotic patients, from the clinical center "La Digonniere" (Saint IZlienne, France), were considered. Table 1 presents general patients characteristics.

PATIENT AGE SEX HEIGHT (cm) WEIGHT (Kg) Scoliotic Shape

;

01

14

F

157.5

38

D11_L4 = 15

(12

14

F

159

44

03

13

F

159

48.5

LI_L4=H D12_L4 = 8 D12J,4 = 20 D9J,2 = 20 D12_L4= 12 1)9 L 3 = 8 D11_L3= 13 I)11_L4= 14 I)5_I)11 = IO mi._L4 = 5

04

14

F

156.5

38

05

11

F

146

40

06

14

M

151.5

32

07

11

F

153

36.5

08

y

F

132

26.5

(•'>

14

F

161

47

10

11

F

133.5

37

Table 1 : general information about patients 2.2 3D Geometry For each patient, front and profile X-rays were taken in a specific calibration device in order to get the radiographic environment . X-rays were scanned with a VIDAR® scanner and the radiographic images were processed with a specific software to obtain 3D reconstruction of spine and pelvis using NSCP method . Accuracy of such reconstruction has been assessed in previous studies for the shape of the vertebrae and pelvis (mean point-surface error 1.5 nun), t h e i r orientation (mean values of rotation : lateral 0.4 . sagittal 0.7 . axial 1.4 ). and the 3D position of vertebral body geometric center i 1 m m ) . 2.3 Foot pressure measurement The basis of stereoradiographic device is equipped by a ZEBRIS® plate-form ( F i g u r e 2 ) . This system permits foot pressure measurement using sensors of 1cm 2 in a sensor area of 32 \ 47 cm 2 , The measurement accuracy is about +/- 5cf.

Static measurement using this platform yields location of projection of the patients' center of gravity. The vertical line based on that point is named GL. Furthermore, the coordinate system of the force platform was located with regard to that of the stereoradiographic evice in order to assess GL location with regard to spine and pelvis. The accuracy was estimated to +/- 1 cm. 2.4 Reference group: A previous study conducted in collaboration with "Tripode" hospital (Bordeaux, France) with the same protocol concerned 34 asymptomatic adult volunteers (mean age 30,5 yrs, range 2 I -53)\ These subjects were considered as a reference group.

2.5 Data processing: Various clinical indices were calculated to characterize the vertebral and spinal deformity as well as patient's posture and imbalance. In the present study we focused on the distance between each vertebra center and the GL. 3. Results A great variability was found among the 10 measured patients. To illustrate this variability, we focused the results on 3 patients who were considered as particularly demonstrative. Figure 4 presents the 3D reconstruction of the spine and the pelvis with regards to the GL tor these 3 patients. Figure 5 shows the projection of vertebra center position w i t h regards to GL. These data are compared with reference group results. Patient 10 has a mild thoracolumbar 5° curve (D11-L4). Although a slight left deviation of the spine is observed, the top view of its vertebral line keeps within those of the reference group, both in the sagittal and frontal directions. Patient 05 has a mild thoracolumbar 20° curve (D9-L2). The frontal view indicates this curvature and a slight right imbalance. The sagittal view shows reduced lumbar curve. On the top view, the vertebral line projection is situated at the borderline of reference group lines. Third, patient 09 has a double curvature (D5-D1 1 and Dl 1-L4, respectively 10° and 14"). The frontal view shows small right global imbalance of this patient. The sagittal view indicates reduced both lumbar and thoracic curves. On the top view, the location of the projection of the vertebral line is also situated at the borderline of reference group data.

-V Champain et al. /Geometric and Postural Analvsis

4. Conclusion The results of this study underline the advantage of combining 3D reconstruction with force pressure measurements in the same coordinate system. This innovative protocol gives the possibility for clinicians to have qualitative observation of the global equilibrium of spine and pelvis for scoliotic patients and quantitative parameters for this observation. This protocol could be used in long-term follow-up study of patients with mild idiopathic scoliosis, in order to better understand biomechanical parameters, which influence scoliosis aggravation.

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5. Acknowledgments The authors gratefully thank « Fondation Yves Cotrel pour la recherche en pathologic rachdienne », Institut de France, for its financial support. References 1.

Clerc AL, Mitton D, Skalli W. Contribution a la semi automatisation des reconstructions 3D du rachis scoliotique et etude de la precision des parametres quantitatifs de la scoliose. 2000, DEA de Biomecanique, ENSAM, Paris. 2. Dumas R, Mitton D, Steib JP, De Guise JA, Skalli W. Pre and Post 3D modeling of scoliotic patients operated with in situ contouring technique. 2002, International Meeting of the IRSSD, Athens, Greece. 3. Duval-Beaupere G. Rib hump and supine angle as prognostic factors for mild scoliosis. Spine 1992; 17:103-7. 4. Duval-Beaupere G, Lamireau T. Scoliosis at less than 30 degrees. Properties of the evolutivity (risk of progression). Spine 1985; 10:421-4. 5. Gangnet N, PomeroV, Dumas R, Skalli W, Vital JM. Variability of the spine and pelvis location with respect to the gravity line: a 3D stereradiographic study using a force platform. Surg. & Radio Anat. 2001; submitted 6. Graf H, Hecquet J, Dubousset J. 3-dimensional approach to spinal deformities. Application to the study of the prognosis of pediatric scoliosis. Rev Chir Orthop Reparative Appar Mot 1983; 69:40716. 7. Labelle H, Dansereau J, Beliefeur C, Jequier JC. Variability of geometric measurements from threedimensional reconstructions of scoliotic spines and rib cages. Eur Spine J 1995; 4:88-94. 8. Mitton D, Dumas R, Laporte S, Leborgne P, Bataille Ph, Quidet D, Skalli W. Simplified calibration system for stereordiography in scoliosis. 2000, International Meeting of the IRSSD, Clermont Ferrand, France. 9. Mitton D, Landry C, Veron S, Skalli W, Lavaste F, De Guise JA. 3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes. Med Biol Eng Comput. 2000; 38:133-9. 10. Mitulescu A, Semaan I, De Guise JA, Leborgne P, Adamsbaum C, Skalli W. Validation of the nonstereo corresponding points stereoradiographic 3D reconstruction technique. Med Biol Eng Comput 2000; 38:133-9. 11. Mitulescu A, Skalli W, Mitton D, De Guise JA. Three-dimensional surface rendering reconstruction of scoliotic vertebrae using a non-stereo corresponding points technique. Euro Spine J 2000, in press. 12. Sahlstrand T, Petruson B, Ortengren R. Vestibulospinal reflex activity in patients with adolescent idiopathic scoliosis. Postural effects during caloric labyrinthine stimulation recorded by stabilometry. Acta Orthop Scand. 1979; 50:275-81.

Tli.B. C/Y/u/A/£
Self-Calibration of Biplanar Radiographs for a Retrospective Comparative Study of the 3D Correction of Adolescent Idiopathic Scoliosis J. Novosad, B.Eng.1-2; F. Cheriet, Ph.D.u; S. Delorme, M.Sc.A.2; S. Poirier, B.Sc.2; M. Beausejour, M.Sc.A.2; H. Labelle, M.D.2 1

Ecole Polytechnique de Montreal, P. O. box 6079, succursale Centre- Ville, Montreal, Quebec, Canada, H3C 3A 7. 2 Sainte-Justine Hospital Research Centre, 3175 Cote-Sainte-Catherine road, Montreal, Quebec, Canada, H3T1C5

Abstract A novel technique for the 3D reconstruction of the spine from X-ray images is presented. The algorithm is based on the self-calibration of biplanar radiographs. It allows the 3D reconstruction of spines from old uncalibrated preoperative and postoperative radiographs. The reliability of the new selfcalibration technique was investigated by validating its results against those of the Direct Linear Transform (DLT) on real images. An accuracy experiment was also performed using a dry spine specimen under controlled conditions. The results indicate that self-calibration is a viable technique, accurate enough to extract meaningful 3D clinical data for retrospective studies.

1. Introduction Current stereo-radiographic 3D reconstruction techniques, like the Direct Linear Transform (DLT), require that a calibration object and a positioning system be used when taking routine clinical radiographs. Therefore, the DLT cannot be used for performing 3D reconstructions from non-calibrated radiographs. This makes it impossible to perform 3D analyses of earlier surgical scoliosis treatments (e.g. Harrington) that have not been performed at Sainte-Justine Hospital since 1993, which is the year the DLT calibration system was introduced. In this paper, a new 3D reconstruction technique is presented that does not require any calibration apparatus. The DLT requires that the x-ray images be taken with a large calibration object surrounding the entire reconstruction volume (the patient's trunk) [10]. Such cumbersome calibration objects are incompatible with operating room setting and thus cannot be used for intraoperative reconstruction. In 1999, Cheriet et al. [1,2] suggested a solution to the intraoperative problem that uses a small calibration object. Implicit calibration algorithms like the DLT are not robust enough to use a small calibration object. Therefore, Cheriet et al. had to propose a state of the art explicit calibration technique that yields very accurate results with only a small calibration object that is conveniently placed over the patient during the acquisition of intraoperative X-rays. Self-calibration is the process of estimating the X-ray source and film locations and orientations relative to the patient's frame of reference from the natural content of the images (anatomical structures, implants, etc.) The algorithm presented in this paper is based on the same mathematical and numerical methods as the explicit calibration

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technique. For a comprehensive exposition to the underlying mathematical framework, the reader should refer to [1]. The main idea is to adjust the geometric parameters that describe the radiographic set-up in such a way to minimize retroprojection errors. The principal difference between self-calibration and explicit calibration is that there is no longer a real calibration object. Instead, the algorithm generates its own "virtual" calibration object by reconstructing anatomical landmarks using approximate geometric parameters. The 3D points of the "virtual" calibration object are updated regularly as the algorithm converges until the system reaches a stable state which reflects a valid solution. This type of calibration method is known as a metric bundle adjustment. According to Polleyfeys [9] this method yields a reconstruction that is accurate up to a rigid transformation and a uniform scale factor. 2. Materials and Methods 2.1 The Initial approximation Self-calibration relies on initial approximations of the geometric parameters that describe the radiographic set-up. The initial approximations used for preoperative and postoperative trunk radiographs are based on the definitions of standard postero-anterior (PA) and lateral (LAT) views (c.f. Table 1). Table 1 : Initial Approximations for PA and LAT Views

The position and orientation parameters are defined with respect to the Scoliosis Research Society (SRS) global coordinate system as described by Stokes [3]. 2.2 In Vitro and In Vivo Experiments In order to test the accuracy of the technique, a dry spine was reconstructed using self-calibration from a postero-anterior and a lateral X-ray taken under controlled conditions. The reconstruction was compared to measurements taken by a coordinate measuring machine (CMM). Self-calibration and the DLT were used to reconstruct spine models from a databank of 20 PA/LAT pairs of postoperative X-rays of patients operated for scoliosis at SainteJustine hospital in Montreal between 1993 and 1998. The pairs of postoperative radiographs were all taken using the same digital X-ray apparatus with the same calibration object. The calibration data was used by the DLT. For self-calibration, anatomical landmarks were used as the "virtual" calibration object.

J. Novosad ft al. /St'lf-ciilihration of Bipltinar Radiograph.

3. Results The dry specimen experiment yielded an RMS reconstruction error of 1.7mm. This experiment shows that the self-calibration algorithm yields an acceptable level of precision. A metric registration was performed on the 20 pairs of corresponding DLT and selfcalibration 3D reconstructions. This procedure computes a rigid transformation and a scale factor between corresponding 3D models. The root-mean-squared (RMS) reconstruction error after registration indicates whether the shape of the spine is preserved between the two reconstructions (c.f. Table 2). 5 of the 20 cases were rejected from the study as they were outliers. They yielded much larger orientation errors and translations, to the order of 20 degrees and 450 mm respectively. For these 5 cases, the self-calibration algorithm's final state indicated poor convergence. In the context of a retrospective study, the detection of poorly converging cases will indicate problematic reconstructions. Reconstruction errors obtained for the 5 rejected cases were possibly due to erroneous landmark identification or non-standard radiographic set-ups (far from the initial approximation). Table 2: Self-Calibration vs. DLT Registration Results

4. Discussion The accuracy of the reconstructions is very promising: best-fit RMS vertex distances are of the same order of magnitude as the expected accuracy of the DLT [6,7]. The absolute position (translation) of the 3D model appears to be subject to a lot of uncertainty. Fortunately, all relevant 3D metrics for the study of scoliosis [3,8] are independent of the spine's absolute position in space. The preservation of scale is important for the evaluation of certain clinical indices. A simple scale correction procedure for the context of self-calibration was proposed by Cerveri [5] that uses a priori knowledge of the dimensions of a few objects in order to recover the scale of the entire scene. This technique can be applied by using knowledge of the dimensions of certain implants (applicable to postoperative cases only). Even without scale correction, the scale error is negligible in all cases (c.f. Table 2). The experimental results show orientation errors of up to 6.71 degrees with the selfcalibration procedure. Many 3D clinical indices are measured with respect to reference planes of specific orientations. Such measurements can be greatly affected by global orientation error. Fortunately, in most cases the orientation error is negligible. 5. Conclusion The results confirm that self-calibration is a viable alternative to the DLT, applicable to radiographs taken without a calibration object. Therefore, this technique is suitable for performing 3D reconstructions for retrospective studies.

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Self-calibration will be used in an upcoming retrospective study of the 3D correction of adolescent idiopathic scoliosis achieved by the Harrington-Luque technique. This surgical technique was widely used at Sainte-Justine Hospital between 1982 and 1987, thus before the introduction of a calibration apparatus for trunk X-rays at the hospital's radiology department. The currently used surgical instrumentations (e.g. Colorado, CotrelDubousset) are very sophisticated, expensive and increase surgery time compared to earlier surgical systems. The main objective is to evaluate and quantify the improvement of postoperative spine 3D correction justifying the use of these new systems. Although the scales and orientations of the models reconstructed for this paper were very good, it should be stated that there are no orientation and scale constraints embedded into the self-calibration algorithm (c.f. [9]). The reason why orientation and scale are so close to reality is because of the quality of the initial approximation. Therefore, it will be important that x-ray acquisitions involved in the retrospective study be consistent with standard specifications. Fortunately, it will be possible to filter-out any cases that do not fulfill this criterion by detecting cases for which the self-calibration algorithm converges with difficulty. The five cases that were rejected earlier all had indeed final retroprojection errors greater than 3 mm. Future work may involve the development of a procedure that automatically generates a close initial approximation of the geometric parameters based on implicit linear methods such as epipolar geometry [4, 5, 9]. References 1. F. Cheriet et al., Towards the Self-Calibration of a Multi-view Radiographic Imaging System for the 3D Reconstruction of the Human Spine and Rib Cage, InternationalJournal of Pattern Recognition and Artificial Intelligence 13(1999) 5: 761 -779. 2. F. Cheriet et al., Reconstruction radiographique peroperatoire de la colonne vertebral scoliotique, Annales de Chirurugie 53 (1999) 8: 808-815 3. I. Stokes, Three-Dimensional Terminology of Spinal Deformity, Spine 19 (1994): 236-248 4. O. D. Faugeras, What can be seen in three dimensions with an uncalibrated stereo Rig? Proceedings of the 2nd European Conference on Computer Vision, G. Sandini (ed.), Lecture Notes in Computer Science, Springer-Verlag, Santa Margherita Ligure, Italy, 1992: 563-578. 5. P. Cerveri et al., Complete calibration of a stereo photogrammetric system through control points of unknown coordinates, Journal of Biomechanics 31 (1998): 935-940. 6. H. Labelle et al., Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages, European Spine Journal (1995) 4: 88-94. 7. L. Chen et al, An investigation on the Accuracy of Three-dimensional Space Reconstruction Using the Direct Linear Transform, Journal of Biomechanics 27 (1994): 493-500. 8. I.A.F. Stokes, L.C. Bigalow and M.S. Moreland, Three-Dimensional Spinal Curvature in Idiopathic Scoliosis, Journal of Orthopaedic Research,(1987) 5 : 102-113. 9. M. Polleyfeys, 3D Modeling from Images, 3DIM Tutorial Lecture Notes, Quebec City, Canada, 2001, 125 pages. 10. J. Dansereau et al., Three dimensional reconstruction of the spin and rib cage from stereoradiography and imaging techniques, Procedings ofSociete Canadienne de Genie Mecanique, 2 (1990): 61-64

Th.fi. Gm-iistEJ.i into Spinal Deformities 4 I OS Press. 22

Semi-automation of the 3D reconstruction of the spine using wavelets and splines Sylvain Deschenes1, Benoit Godbout1, Wafa Skalli2 and Jacques de Guise1 /. Laboratoire de recherche en imagerie et orthopedie, CRCHUM, ETS 1560Sherbrooke E., Montreal (Quebec), H2L 4M1, Canada 2. Laboratoire de biomecanique, Ecole Nationale Superieure des Arts et Metiers, 151 del'Hopital, 75013, Paris, France

•Abstract We propose a wavelet multi-resolution analysis to localize specific features in both lateral and frontal radiographs. This analysis allows an elegant spectral investigation that leads simultaneously to image de-noising and edge extraction. It is combined with an a priori knowledge of the spine's morphology and a 3D spline curve characterization of its global shape. Actual work deals with identifying the contours of the vertebral bodies and the localization of vertebrae's endplates. However, this information could also lead to the selection of a 3D statistical model of the spine suited for the studied deformation. Working with retro-projections of the model, we aim at creating edge models for each vertebra that will be used to geometrically match the wavelet's edges. The manual feature identification could then be replaced in the reconstruction of the 3D representation of the spine.

1. Introduction Since almost fifteen years, computer techniques were developed to perform the 3D reconstruction of the spine from two radiographs. Sadly, these methods imply a manual identifying of several stereo-corresponding and sometimes non-stereo-corresponding points in both images [1]. Locating these features is time-consuming and the interaction with the user is often error prone. Besides, an ideal computer assisted method would ask a minimal number of exchanges with the clinician and provide fast and accurate reconstruction results. It should compute results in a repeatable way, contributing to the development of multicentric studies. Therefore, to overcome the inconveniences brought by the manual approach, we propose semi-automatic algorithms that encompass in many ways the desired characteristics. To begin with, a 3D spline interpolator provides a good estimate of the spine's global deformation as well as the relative 3D positions of the vertebrae in space. This paper shows image processing techniques that facilitate the extraction of such features to compute correctly the 3D reconstruction parameters. Namely, the stationary wavelet transform, multi-resolution analysis and edge extraction are described. Furthermore, edge classification using statistical models, active contours and curvature characterization algorithms are efficiently applied to localize the vertebral bodies' surroundings and delimitate endplates from vertebral body's walls.

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2 Required input and a priori knowledge To produce a time effective method, it is advantageous to study radiographs' content exclusively on a few targeted regions. This can be done using a priori knowledge of the vertebrae's morphology and minimal input from the user. First, we consider statistical data to evaluate the relative dimensions of vertebrae along the spine. Then, the user is asked to click a small number of points along the spine on both radiographs, indicating its general shape, from Tl to L5. 2.1

3D spine spline

From the points clicked along the spine on the frontal and lateral images, we can generate a 3D curve representing the spine in space. Among these points, only the centre of the superior endplate of Tl and the inferior endplate of L5 need to be identified. All other points can be located anywhere along the spine. As show in Figure 1, these points feed a 3D spline interpolator that generated the best smooth curve fitting these data. Hence, we call this curve the 3D spine spline.

Figure 1. Spine spline interpolator

From statistical study of scoliosis by Muriel Vaiton [2], we can estimate the position of each vertebral body's centre and their retro-projection in both images. The same study also evaluates the values of inter-vertebral gaps. This allows to define an angular orientation of the vertebral body in each radiograph as well as an approximate scale of the vertebra. Note that these evaluations can be considered accurate only in a calibrated environment. Once we have estimates of the vertebral bodies' scale, position and angular direction, it is possible to define a set of minimal regions of interest (ROI) in both images. These ROI are built to be of minimal area while enclosing entirely the vertebral bodies. This way, computation won't be performed on regions where no information would be useful for our analysis.

2.2 Statistical mean model definition The localization of structures in an image requires models to be matched. In this case, we identify the bone structures with the simple geometric shape of an anvil, as seen in Figure 2. Since we deal with edge features, the vertebral body is decomposed in a set of linear segments, representing its endplates and walls. A linear segment describes the end plates and two linear segments shaping a narrowing characterize the walls. Using the scale

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.V. Dcxchcncs et til. / St'iiii-tmtanuition of the .U) Reconstruction of the Spun-

previously computed, the dimensions of the models are calculated from statistical anatomical data found in the literature [3j |4]. The narrowing is evaluated as 95ri of the upper end plate for the thoracic vertebrae and 85^ for the lumbar vertebrae. Superior cndplate

+

>

Fisrure 2. Generic model lor ihe vertebral hodv

3. Multi-resolution analysis Since radiographic images can exhibit important variations in intensity, mainly due to the acquisition's parameters and the nature of the human body reacting to X-rays, a multi-resolution edge-based approach is chosen. .^. / Shitionarv \\-itvelct transform We choose the stationary wavelet transform (SWT) as the multi-resolution analyzer tor the vertebral bodies|5]. This provides multi-scale edges while keeping translation in variance from one resolution to the other. As shown in Figure 3. the SWT algorithm decomposes the image in different frequency bands, using a pair of quadrature mirror filters: a low-pass filter F that sets the resolution and a high-pass filter G that extracts the details.

Figure 3. 2D Stationarv Wavelet Transform Algorithm

The SWT can then be represented as a gradient vector map. Given a single resolution step and detail representations [)"" and D'". or. to simplify the notation. H and \'. pixels in the image can be expressed as a gradient-vector with norm and angular direction given b\

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The edges with strong gradient magnitude will tend to be recurrent in many resolution levels [6]. Since translation invariance has been gained from the SWT, this recurrence will later be used as weight for best-fit algorithms that will generate the contours. 3.2 Denoising and non-maxima suppression The gradient map obtained in Eq. 1 is then processed to get rid of noisy features and smaller non-significant edge details in the image. First, a threshold is computed to eliminate gradients that are too weak and are therefore associated with noise and trivial features. Since radiographic images deal with Poissonian, non-additive noise, we choose to apply an automatic threshold evaluation technique based on the work of Birge and Massart [7]. After eliminating all edge pixels for which the gradient norm is inferior to the threshold, a non-maxima gradient suppression is applied. A new edge pixel is created only when the gradient norm is maximal with respect to its two interpolated neighbours.

4. Feature classification and endplates localization Edge representations, obtained with the SWT, are submitted to chaining and linking to convert the edge images into curve lists. Our main goal is to match these curves with the model's piece wise linear contour. We extract the edge curves that show linear behaviour, up to a given tolerance. This is done using the curvature function, defined as the derivative of the tangent to the curve. With this definition, linear portions of curves are characterized by a small constant curvature. Then, a linear regression algorithm, based on a least-square optimization, helps sorting the segments. Finally, criterions based on the position and slope of the segment's best-fitted line provide a classification into four subsets: superior endplates, inferior endplates, anterior wall, posterior wall. Each subset forms a cluster of points in 2D image space. A polynomial interpolation of order 11 is applied to the clusters to produce four smooth curves representing the walls and endplates of the vertebrae. These curves are linked using cubic spline interpolation in polar coordinates. The resulting closed curve is then smoothed and sent to an active contour algorithm[8]. 5. Results and discussion The application of the algorithms presented in this paper on a lumbar vertebra is shown in Figure 4. After the SWT and sorting of the extracted edges, the use of interpolations, both polynomial and cubic spline, generated initial contours. The final contours were obtained after applying only one iteration of the active contour scheme. This shows the fast convergence provided by our initial solution. Further ameliorations of the method deal with replacing the piecewise linear model by a more accurate edge models, based on existing 3D models of vertebrae, and more powerful matching schemes. Work is also under way to automatically localize the general shape of the spine in radiographs.

\ DCM hcnt's ct { the Spint

Figure 4. Image processing workflow

6. Conclusion We propose new computer assisted techniques based on a multi-resolution analysis using spline and stationary wavelets. The first results produced by this automated contouring method are promising. Moreover, we are now studying new improvements regarding the automation, including a reduction in information asked to the user and the use of more sophisticated models. Acknowledgements We would like to thank our sponsors, Natural Science and Engineering Council of Canada, Valorisation Recherche Quebec, Biospace France and Surgiview, without whom this work couldn't have been done. References 1. D. Mitton et a/., 3D reconstruction method from biptonar radiography using non-stereo-corresponding points and elastic deformable meshes, Medical and Biological Engineering & Computing, Vol. 38, 2000, pp. 133139, 2. M. Vaiton, Reconstruction rapide en trois dimensions de colonnes vertebrates scoliotiques a partir d' image radiologiques, Memoire de maitrise presente a I'lnstitut de genie biomedical de I'Ecole Potytechnique de Montreal, 2000. 3. M.M. Panjabi et al, Thoracic Human Vertebrae: Quantitative Three-Dimensional Anatomy, Spine, Vol. 16, No 8,1991, pp. 888-901. 4. M.M. Panjabi era/., Lumbar Human Vertebrae: Quantitative Three-Dimensional Anatomy, Spine, Vol. 17, No 3,1992, pp. 299-306. 5. R.R. Coifrman, D.L. Donoho, Translation Invariant De-Noising, in Wavelets in Statistics, Springer Verlag, New York, 1995, pp. 125-150. 6. S. Mallat, S. Zhong, Characterization of Signals from Multiscale Edges, IEEE Trans, on PA ML Vol. 14, No 7, Jury 1992, pp.710-732 7. Birge\ Massart, From model selection to adaptive estimation, Festchrift for Lucien Lecam : Research Papers in Probability and Statistics (D. Pollard ed). Springer Verlag 1997, pp. 55-87. 8. Kauffmann, C., Godbout, B., J. de Guise, Simplified Active Contour Model applied to bone structure segmentation in digital radiographs, Proc of SPIE, Image Processing, San Diego, California, Vol. 3338, February 1998, pp. 663-672.

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3D Biplanar Statistical Reconstruction of Scoliotic Vertebrae S. Benameur1'3'5, M. Mignotte3'1, S. Parent1-2, H. Labelle2, W. Skalli4, and J. A. De Guise1'2'5 1. Labor'atoire de recherche en imagerie et orthopedic, CRCHUM Hopital Notre-Dame, Montreal 2. Laboratoire d'imagerie en scoliose 3D, Centre de recherche, Hopital Sainte- Justine, Montreal 3. Laboratoire de vision et modelisation geometrique, DIRO, Universite de Montreal 4. Laboratoire de biomecanique, Ecole nationale superieure d'arts et metiers, Paris, France 5. Ecole de technologie superieure, Montreal, Canada Abstract. A new 3D reconstruction method of scoliotic vertebrae of a spine, using two calibrated conventional radiographic images (postero-anterior and lateral), and a global prior knowledge on the geometrical structure of each vertebra is presented. This geometrical knowledge is efficiently captured by a statistical deformable template integrating a set of admissible deformations, expressed by the first modes of variation in the Karhunen-Loeve expansion of the pathological deformations observed on a representative scoliotic vertebra population. The proposed reconstruction method consists in fitting the projections of this deformable template with the preliminary segmented contours of the corresponding vertebra on the two radiographic views. The 3D reconstruction problem is stated as the minimization of a cost function for each vertebra and solved with a gradient descent technique. The reconstruction of the spine is then made vertebra by vertebra. The proposed method allows also to efficiently obtain an accurate 3D reconstruction of each scoliotic vertebra and, consequently, it allows also to get an accurate knowledge of the 3D structure of the whole scoliotic spine. This reconstruction method is in final phase of validation.

1. Introduction The scoliosis is a three-dimensional deformation of the natural curve of the spinal column, including rotations and vertebral deformations. In order to analyze 3D characteristics of these deformations, which can be useful for the design, the evaluation and the improvement of orthopedic or surgical correction, several 3D reconstruction methods have been developed. The methods using a limited number of projections and some simple a priori knowledge on the geometry of the object to be reconstructed are interesting but are widely supervised; for example it may require to manually identify (by an operator) a set of 19 different landmarks on the two different radiographic images (postero-anterior (/PA) and lateral (/LAT)) of 17 lumbar and thoracic vertebrae [7][8]. In addition to being highly operator dependant, these methods do not exploit all the information contained in the two radiographic images (e.g., the contours of each vertebra)[4][7]. In this way, we propose a new statistical 3D reconstruction model for the scoliotic vertebrae from biplanar radiographic images. Our approach relies on the description of each vertebra by a deformable template which incorporates statistical knowledge about its geometrical structure and its pathological variability. The deformations of this template are expressed by the first modes of variation in the Karhunen-Loeve (KL) expansion of the pathological

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deformations observed on a representative scoliotic vertebra population. This prototype template, along with the set of admissible deformations, constitute our global prior model that will be used in order to rightly constraint the ill-posed nature of our 3D reconstruction problem. In our application, the proposed method consists in fitting this template with the segmented contours of the corresponding vertebra on the two calibrated radiographic views. This matching problem leads to an optimization problem of a cost function, efficiently solved in our application by a gradient descent algorithm initialized by a rough and rigid 3D reconstruction method estimated in the least square sense. This paper is organized as follows. Section 2 and 3 present the statistical deformable model and the proposed 3D reconstruction method. The experimental results of our 3D reconstruction method are presented in Section 4. Finally, we conclude the paper in Section 5 with a conclusion. 2. Statistical Deformable Model The statistical deformable model under concern has been introduced by the authors in [1]. The shape s of each vertebra is defined by a set of n control points "landmarks", which approximate the geometrical shape of each vertebra in 7/?3 [3]. In the following, we will assume that s is a realization of a random vector that follows a normal law of mean vector S and covariance matrix C as suggested in [3]. After aligning of the training shapes, we calculate the mean shape and the covariance matrix. A Principal Component Analysis (PCA) on the displacement vectors S = S — 5 computed from the set of vertebra database allows to deduce the deformation modes relative to the mean shape. The eigenvectors of the covariance matrix C of this random vector describe the information on the variability of the scoliotic deformations in the vertebra database and the associated eigenvalues are the amplitudes of these variation modes. An accurate description of the main variation modes may be obtained by retaining only the m eigenvectors associated to the m largest eigenvalue [3]. The model allows the generation of new instance of the shape by adding linear combinations of the m most significant variation vectors to the mean shape,

s=~s+b,

(i)

with 0 represents the matrix of the first m variation modes of the models of the vertebra base, and b is the global deformation parameter vector setting the amplitudes of each deformation mode b-t. By ensuring,

&, 6 E-3/1;,+3/^1

only the important deformations are extracted, discarding training data noise [3]. This low parametric representation of a vertebra constitutes our global prior model that will be used in our 3D reconstruction method. (1)

3. 3D Reconstruction Besides the above mentioned global deformation parameters, we also consider 3D global transformations from the similarity group which finally lead to the following model for global deformations,

s= rKk/a)[s+Qb]+ 7\

(2)

with Tis a global translation vector, and M(k,a) performs a rotation by (or, / a 2 / a 3 ) around the x, y, and z axis respectively and a scaling by k.

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In order to ensure a first crude and rigid reconstruction of each vertebra, we use the technique proposed in [6] to estimate the position of six anatomical points (namely, the center of the superior and inferior end-plates, the upper and lower extremities of both pedicles) for each vertebra of the spine. The corresponding points on the shape of the mean vertebra being known, we can compute an initial estimate of the parameter vector (k, a T). This leads us to a crude and rigid reconstruction for each vertebra that will be then refined by our 3D reconstruction model. Our reconstruction model from two radiographic views is stated as the minimization of the following cost function, £(s,0) = £,(*,/ PA ,/ LAT ) + 0 *£,(*), (3) where E\ is the likelihood energy term and Ep is the prior energy term, used to constrain the ill-posed nature of this optimization problem. )3 is a factor that provides a relative weighting between the two penalty term and allows to control the rigidity of the statistical template [5], and &=(M(k,a), T, b) is the deformation parameter vector of the model to be estimated. In our application, the likelihood energy term is expressed by a measure of similarity between the external contour of the lateral and the postero-anterior perspective projections of the deformed template and the spatial edges detected in the two radiographic views. It attains its minimum value when there is an exact correspondence between the projected contours (of the deformed template) and the preliminary segmented contours of the two radiographic views. The prior energy term penalizes the deviation of the deformed template from the mean shape. This term does not penalize affine transformations. Finally, Equation (3) is minimized by a gradient descent technique initialized by the estimations given by the rigid reconstruction technique. 4. Experimental Results In our application, we use the vertebra database constituted of 1020 thoracic and lumbar vertebrae (510 normal and 510 scoliotic). Details of this database have been presented in [9]. The mean vertebra shape of each vertebral level is computed on sample of 30 normal vertebrae. The deformation modes of each vertebral level is computed on a sample of 30 scoliotic vertebrae. We have used the Canny edge detector to estimate the edge map on the two radiographic views [2]. In our application, we have chosen to take the number of deformation modes that allows to represent at least 90% of the admissible deformations for each type of vertebra. Besides, experiments have shown that the crude and rigid reconstruction procedure is not always a good initialization for the gradient-based optimization technique. In order to overcome this problem, our solution consists in placing the template at evenly spaced positions and in deforming it according to a discretized set of translation orientation or scale (corresponding to the rigid parameters) within a range of value around the initial estimate obtained by the rigid reconstruction procedure. These deformed template configurations can then be used to initialize a deterministic gradient descent algorithm. However, the spacing between the template positions and the sampling of the transformations must be chosen judiciously: not too spaced out to cover all the significant local minima of the energy surface and not too small to avoid high computational requirements. For the experiments, we have chosen P =1 for the weighting factor penalizing the prior energy term with respect to the external energy. Figure 1 and Figure 2 present

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projections of the shape of a L2 and T8 vertebra on postero-anterior and lateral radiographic images for a scoliotic patient.

(o)(b) Figure 1. Visualization of: (a) the projections of the shape of a L2 vertebra on postero-anterior and lateral radiographic images, (b) L2 reconstructed vertebra : coronal and axial view.

Figure 2. Visualization of: (c) the projections of the shape of a T8 vertebra on postero-anterior and lateral radiographic images. (d) T8 reconstructed vertebra : coronal and axial view. 5. Conclusion We have presented an original statistical method of 3D reconstruction of scoliotic vertebrae using both the contours extracted from biplanar radiographic images and a prior knowledge on the geometrical structure of each vertebra. The proposed scheme thus constitutes an alternative to CT-scan 3D reconstruction with the advantage of low irradiation and will be of great interest for 3D clinical applications and for reliable geometric models for finite element studies. This reconstruction method is in final phase of validation. Acknowledgements The authors would like to thank, the Natural Sciences and Engineering Research Council of Canada, the research center of the Sainte-Justine Hospital, Montreal, Canada, the research center of CHUM, Montreal, Canada, and Biospace, Paris, France, for supporting this study.

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References 1

S. Benameur, M. Mignotte, S. Parent, H. Labelle, W. Skalli, and J. De Guise. 3D Biplanar reconstruction of scoliotic vertebrae using statistical models. IEEE Computer Society Conference on Computer Vision and Pattern Recognition, CVPR'2001, Kauai Marriott, Hawaii, USA, Vol.2, pp. 577-582,2001.

2

J. Canny. A Computational Approach Edge Detection. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol.8, N°6, pp. 679-697, 1986.

3

T. F. Cootes, C. J. Taylor, D. H. Cooper, and J. Graham. Training models of shape from sets of examples. Proc. British Machine Vision Conference. Springer-Verlag, pp.9-18, 1992.

4

J. A. De Guise, H. Mallouche, J. Dansereau, and H. Labelle. Imaging Techniques Applied to Spinal Biomechanics. Journal of Biomechanics, Vol.7, N°3, pp. 135-144,1995.

5

A. K. Jain, Y. Zhong, and S. Lakshmanan. Object Matching Using Deformable Templates, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol.18, N°3, pp. 267-278,1996.

6

C. Kauffman, and J. A. De Guise. Digital radiography segmentation of scoliotic vertebral body using deformable model. SPIE, Vol. 3034, pp. 243-251, 1997.

7

D. Mitton, C. Landry, S. Ve"ron, W. Skalli, F. Lavaste, and J. A. De Guise. 3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes. Medical & Biological Engineering & Computing, Vol.38, pp. 133-139, 2000.

8

A. Mitulescu, I. Semaan, J. A. De Guise, P. Leborgne, C. Adamsbaum, and W. Skalli. Validation of the non-stereocorresponding points stereoradiographic 3D reconstruction technique. Medical and Biological Engineering and Computing, Vol.39, pp. 152-158, 2001.

9

S. Parent, H. Labelle, W. Skalli, Bruce Latimer, and J. A. De Guise. Morphometric Analysis of Anatomic Scoliotic Specimens. Spine, 2002, accepted.

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3D Detailed Reconstruction of Vertebrae with Low Dose Digital Stereoradiography A Le Bras'. S. Laporte1, D. Mitton1, J.A. de Guise1-2 , W. Skalli1 (1) Laboratoire de Biomecanique, ENSAM-CNRS Paris, France (2) Laboratoire de Recherche en Imagerie et Orthopedic (ETS-CRCHUM), Montreal, Canada Abstract; As scoliosis requires a global and local 3D examination of the spine in standing position, Stereoradiography appears as one of the most adequate 3D imaging tool for it diagnosis. Our purpose was to increase the geometry definition of the stereoradiographic reconstruction to obtain morpho-realistic models and to validate them using 41 dry vertebrae. Our results propose 2000 points 3D personalised models without any loss of accuracy in comparison to previous studies'"'.

1. Introduction Several clinicians insist on the importance of global and local 3D deformation in the pathologic spine analysis [14J(31 [15]. In the aim to plan and evaluate their surgical acts, they need more and more accurate morphological informations coming from 3D imaging modalities. Among 3D acquisition methods, Stereoradiography stays the only one allowing a 3D rendering of the whole spine in the upright position with an acceptable irradiating dose. The development of a low dose digital X-ray device (EOS™, Biospace Instruments, France) permitting an irradiating dose 10 at 30 times lower than in conventional X-ray (6' makes this technique promising for routine clinical diagnosis In the first applications of Stereoradiography, 3D representations of the spine were obtained using the DLT algorithm [161113)>[4). It allowed a reconstruction of a very limited number of reconstructed points per vertebra because of the necessity to have anatomical landmarks identifiable on both radiographs (stereocorresponding points). A real advance in this technique was the development of the NSCP algorithm [9]. This algorithm, based on an a priori knowledge of the 3D mean generic object gave the possibility to reconstruct non-stereocorresponding points. This allowed having 3D representations with accuracy close to 3D CT-scan reconstructions191'1'01. Despite of this good accuracy, personalised reconstruction was not enough morpho-realistic because of the limited set of points defining the generic object (150 to 214 points per vertebra). The aim of this study was to propose and validate a method allowing very detailed and accurate personalised reconstruction (2000 points per vertebra), using EOSi system. 2. Materials and Methods 63 dry vertebrae coming from the Laboratoire d'Anatomic des St Peres (Paris, France) were used for this study. These vertebrae were divided in 2 subsets. Subset A contained 1 non-pathologic vertebrae per level from C3 to L5 (i.e. 22 vertebrae). It was used to define a detailed generic object for each vertebral level and was not taken into account for the validation method protocol. Subset B, containing 36 non-pathological (10 inferior cervical vertebrae, 12 thoracic vertebrae and 14 lumbar vertebrae) and 5 scoliotic vertebrae was used for the validation protocol. We briefly remain existing reconstruction method, which details have already been presented191, then we present the adaptation to improve morphorealism. The 3D-

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stereoradiographic reconstructions were obtained using the SCP, NSCP and kriging algorithms1181. Kriging consists in deforming a generic object with regard to a set of control points to fit to on a specific object containing some of the same identified control points. In this study, this method was extended to obtain 2000 points reconstructed models. The main steps and specificity of the current method will be given in the following parts. 2.1

Generation of Detailed Generic Object

Existing generic objects were taken from a database of 3D direct measurements (accuracy error< 0.2 mm) obtained in previous studies18"51'117"121. This database provided the average 3D geometry (10 to 30 vertebrae per level) for an approximately 200 points set per vertebral level. To improve the morphology definition of this existing generic objects described above, we used for each vertebral level a 3D CT-scan reconstruction containing up to 2000 points. The dry vertebrae coming from the subset A were all scanned in a CT-scan device at the Centre d'Imagerie Veterinaire (Billancourt, France) with the following CT settings: slices thickness of 1 mm and slice spacing of 0 mm. The 3D reconstruction was realised using the SliceOmatic® software by piling the CT slices of the vertebrae and using the standard marching cube reconstruction p]. At first, bone surfaces on each CT slice are recognised by an automatic segmentation of grey level, then a manually correction of the potential segmentation errors are realised and finally the 3D reconstruction is performed containing up to 2000 points. However this 2000 points CT-scan models are not usable for NSCP + kriging technique because they have no control points and they are not representative models of a vertebral level. On these CT-scan reconstructions, an infographic method [191 was applied to extract semiautomatically the set of points corresponding to the generic objects described above (150, 214 and 178 points for the cervical, thoracic and lumbar vertebrae respectively). These points were then associated with the CT-scan reconstruction in order to use them as control points for our future 2000 points models. Finally, the control points associated with the 2000 points specific mesh were kriged, on the corresponding average models to obtain a 2000 points average model for each vertebral level (Figure 1).

2.2

Validation of the method

The calibration of the radiological environment was realised with a modified DLT algorithm to fit to the specificity of the low dose digital systemtll] in order to obtain the 3D parameters of the radiographic device. For all specimens of the subset B, depending on the specificity of the vertebral level and the radiographs visibility, 20 to 28 landmarks per vertebra were identified, i.e. from 8 to 13 stereo-corresponding points and from 13 to 19 non-stereo-corresponding points.

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Once the 3D co-ordinates of these controls points are obtained (DLT+NSCP), the deformation of the detailed generic object is realised using extrapolation and interpolation algorithms ("kriging"), which yields an approximate global shape of a given vertebra that is consistent with the 3D co-ordinates of the control points. Finally a detailed personalised model with 2000 points is obtained. All vertebrae were then CT-scanned and reconstructed with the same protocol reconstruction defined for the detailed generic object generation. The accuracy of this reconstruction technique protocol was evaluated at ± 1mm [7]. They were used as reference reconstruction for the comparison with the 3D detailed stereoradiographic model. The comparison consisted in superimposing the two models by using geometrical transformation (rotation, translation) and a least square matching method. On a first step, a qualitative comparison was performed to have an idea of how adequate the reconstructed shape is, when compared to the reference vertebral topology (CT scan). Moreover, visualisation of the superimposed reconstruction of the same vertebra makes visible the vertebral regions where maximum deviations may occur. On a second step, to quantify the accuracy of the stereoradiographic technique with regard to the reference technique (CT-scan), the results of the comparisons were expressed as point to surface distances. After superimposition, each point of the model (obtained from stereoradiography) was projected on the surface defined by the reference (obtained from the CT scan) in order to calculate the point to surface distance I91"01. The mean point to surface distance, the 2 RMS (2 Root Mean Square, representing the maximal error for 95 % of the points) and the maximum distance values (representing the isolated extreme values obtained for the entire sample) were evaluated. This comparison was processed on the entire set of 2000 points per vertebra for the whole sample with regard to 3D CT scan reconstruction. 3. Results A qualitative evaluation of reconstructed vertebrae was realised. An example is shown for a thoracic vertebra (figure 2).

The quantitative results of the point to surface comparisons between detailed stereoradiography reconstruction and CT scan technique are presented in Table 1 as mean, 2 RMS and maximum value and for the entire sample of 36 vertebrae and the scoliotic ones. Table 1; Results of the quantitative comparison between detailed stereoradiographic reconstruction and CT-scan reconstruction

Point to surface error (mm) Mean 2RMS Max Non-pathok>gical vertebrae (36 vertebrae)

0.9

2.2

5

5 Scoliotic vertebrae

1.1

2.5

6

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4. Discussion The qualitative evaluations of the reconstructed vertebrae proved realistic morphological shapes and quite similar to the CT scan ones. Moreover, this is the first study about stereoradiographic reconstruction accuracy considering the geometric specificity of each spine level visible on a classical spine radiograph (from C3 to L5). The quantitative results showed error comparable to previous studies (the previous more accurate one showed an average error of 1.1 ± 2.8 mm for lumbar vertebrae [IO] whereas the current models taking into account a very larger set of points. Indeed, approximately 2000 reconstructed points are evaluated for the current model versus only 178 points for the previous most detailed one l101. Therefore, this is a real improvement compared to all the previous stereoradiographic reconstruction method [1I>191>110]. These very encouraging results are certainly due in one way to the image quality permitting a good visibility of specific anatomical points and contours of the X-rayed vertebrae, and in an other way to the iterative control process allowing fitting the real radiograph contours with the retro-projected ones. But this capacity of control is only possible thanks to the high detail level of the 3D model, which allow a very realistic retro-projection. The maximal errors (~ 6mm) for certain cases could be explained by osteophyts on few vertebrae. Effectively, this reconstruction method using the deformation of a generic mean object can produce local deformation induced by a global deformation (case of a degenerative scoliotic pathology for example) but it can not take into account important local deformation caused by a local degenerative pathology. This fact could be explained by the limitation of the NSCP algorithm, which can deform the generic object only in the region where geometrical informations (anatomical landmarks identified by the operator) are sufficient. Nevertheless, integrating a non-stereocorresponding contours algorithm in the 3D-stereoradiographic reconstruction method could probably diminish the higher reconstruction errors. 5. Conclusion The results showed high accuracy of the detailed reconstruction models obtained from the low dose X-ray device. As the X-ray dose is significantly diminished and the personalised 3D geometric models seem to be quite accurate, this new 3D imaging technique could be a good alternative to existing techniques for the follow-up of scoliotic patients, allowing quantitative 3D analysis. Moreover this method could give a very detailed geometry for personalised finite element model, and thus showed a real progress in the planning of surgical acts. 6. Acknowledgements The authors thank A. Mitulescu for her technical advice as well as Biospace Instruments for financial support.

References 1 2 3 4

Aubin CE, Dansereau J, Parent F, Labelle H, de Guise JA (1997): Morphometric evaluations of personalised 3D reconstructions and geometric models of the human spine. Med Biol Eng Comput 35: 611-618 De Guise J.A., Martel Y., (1988): 3D biomedical modelling: merging image processing and computer aided design. IEEEEMBS 10th International Conference, New Orleans, pp. 426-427. Dubousset, J. (1992) : Importance of three-dimensional concept in the treatment of non scoliotic deformities. Proc. Int. Symp. 3D Scoliotic Deformities, Montreal, Quebec, Canada, pp. 302-311. Dansereau J. and Stokes, I.A.F. (1988) : Measurements of three-dimensionnal shape of the rib cage. J. Biomech., 21, pp. 893-901.

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Ismael B. (1995): Etude morphometrique des vertebres thoraciques.Memo\Te de DEA, LBM ENSAM, Paris 6 Kalifa G., Boussard J.M. (1996): L'appareillage de radiologie numerique dit Charpak. J. Radio!., pp 77-85 7 Landry C., de Guise J.A., Dansereau J., Labelle H., Skalli W., Zeller R. and Lavaste F. (1997): Analyse infographique des deformations tridimensionnelles des vertebres scoliotiques. Ann. Chir., 51, pp. 868874. 8 Maurel N. (1993): Modelisation geometrique et mecanique tridimensionnelle par elements finis du rachis cervical inferieur. These de doctoral en mecanique, LBM-ENSAM, PARIS. 9 Mitton D., Landry C., Veron S., Skalli W., Lavaste F., and de Guise J.A. (2000): 3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes. Med. Biol. Eng. Comput., 38, pp. 133-139. 10 Mitulescu A., Semaan I., de Guise J.A., Leborgne P., Adamsbaum G., and Skalli W. (2001): Validation of the non-stereocorresponding points stereoradiographic 3D reconstruction technique. Med. Biol. Eng. Comput., 39, pp. 152-158. 11 Mitulescu A. (2001). Contribution a la reconstruction tridimensionnelle du rachis et du bassin a partir de la ste~reoradiographie conventionnelle et basse dose (Charpak). These de Doctoral de I'ENS AM, Specialite Mecanique. 12 Parent S.et al. (2000): Morphometry of normal thoracic vertebrae. In CORS 2000. 13 Pearcy M J.,Whittte M.W.( 1982): Movements of the lumbar spine measured by three-dimensionnal X-rayanalysis. 3. Biomed Eng., 4, pp. 107-112.

14 PenJrioUe R. (1979): La scoliose: son aspect tridimensionnel in Mak)ine(Ed.), Paris. 15 Rainaut J J. (1994): Les scolioses. Ellipse (Ed.), Paris. 16 Selvik G., Olsson T.H., and Willner S. (1976): High accuracy analysis of movement of the spine with the aid of a roentgen stereophotogrammetry method. Biomechanics V-B. Edited by P.V. Komi, University Park Press, Baltimore Maryland, USA, 1976, pp. 502-507. 17 Semaan I.(1997): Etude morphometrique des vertebres lombaires.'MtmoiK de DEA (LBM, ENSAM, Paris). 18 Trochu F.(1993): A contouring program based on dual kriging interpolation. Eng. Comput.. 9, pp. 160177. 19 Veron S. (1997): Modelisation geometrique et mecanique tridimensionnelle par elements finis du rachis cervical superieur. These de doctoral en mecanique, LBM-ENSAM, Paris.

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Pre and Post 3D Modeling of Scoliotic Patients Operated with In Situ Contouring Technique R. Dumas(1), D. Mitton(1), J. P. Steib(2), J. A. de Guise(3), W. Skalli

CD

(/)

Laboratoire de Biomecanique, ENSAM-CNRS, Paris, France m Hopitaux Universitaires de Strasbourg, France <3> Laboratoire de recherche en Imagerie et Orthopedic, ETS-CRCHUM, 5.1 Montreal, Canada Abstract. A three-dimensional segmental analysis was performed on the stereoradiographic reconstructions of ten right thoracic scoliotic patients. From the quantitative model of the spine and pelvis, the vertebral and intervertebral orientations were computed pre and post operatively. These orientations allow to determine the apical and junctional zones of the high thoracic, thoracic and lumbar curves. The apical zone corresponds to the maximum of vertebral axial rotation. Pre operatively, the tendency was T7 for the thoracic transverse apex with 20,/Eof axial rotation. The junctional zone corresponds to the maximum of vertebral lateral rotation and the maximum of intervertebral axial rotation. The tendency was T5 and T12 for the junctional vertebrae of the thoracic curve with, at both levels, 3QJE of vertebral lateral rotation and \OJE of intervertebral axial rotation. The surgical correction obtained by in situ contouring technique was evaluated through these 3D orientations. The vertebral axial rotation at the high thoracic, thoracic and lumbar apex was corrected with respectively 52%, 60% and 60%.

1. Introduction Several authors have pointed out the importance of the three-dimensional concept in scoliosis management. Among them, Perdriolle [1] and Dubousset [2] described a three dimensional segmental analysis. They observed, on one hand, the apical zones with maximum of axial rotation (without intervertebral axial rotation) and segmental lordosis in thoracic levels (intervertebral sagittal rotation) and, on the other hand, the junctional zones with maximum lateral rotation and intervertebral axial rotation. However, the three-dimensional deformity and the surgical correction evaluation are generally assessed plane by plane with global measurements (Cobb angles, lordosis and kyphosis). When multiplanar radiography is used, the reported measurement [3] is still global, with the plane of maximum deformity. As for the segmental (vertebral) orientation, the analysis is generally limited to the axial rotation, studied by frontal radiography, CT-scan [46], and intra-operative measurements [7, 8]. Moreover, the axial rotation remains controversial, due to variations and accuracy of computation methods and application difficulties. Using a quantitative stereoradiographic reconstruction [9], the purpose of this study is to assess, pre and post operatively, the segmental orientations, which are the characteristic of the curve (at the apical and junctional vertebrae).

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2. Materials and methods Ten scoliotic patients, 7 adolescents (13 to 19 years old) and 3 adults (33, 34 and 54 years old) presenting a basic right thoracic curve (5 double thoracic and lumbar and 5 triple curve patterns) were included in this study. The mean Cobb angle was 56° (range 36 ° to 78°). All patients underwent a surgical correction with the in situ contouring [10] technique at the Hopitaux Universitaires de Strasbourg. Pre and early post operative standing frontal and lateral X-rays were taken using a stereoradiographic device [11]. The patient's spine, from the 7th cervical vertebrae to the pelvis, was reconstructed in 3D by stereoradiographic methods using NSCP technique [9]. According to the SRS definition [12], the global axis system and the local (vertebral) axis systems were constructed. The vertebral orientation with regard to the global axis system and the relative inter-vertebral orientation (one vertebra with regard to the inferior one) were calculated using the LSA (Lateral, Sagittal, Axial) sequence [13]. The error of orientation has been evaluated in several combined rotations of a vertebral specimen and demonstrated 0.6 ° (0.5 °), mean and (SD) for lateral rotation, 0.7 ° (0.7 °) for sagittal rotation and 1.4 ° (1.3 °) for axial rotation. On three curves: the high thoracic (counter) curve (A), the thoracic curve (B) and the lumbar (counter) curve (C), the following characteristics were computed from the 3D reconstructions (see Figure 1): • • • •

In a junctional zone, the vertebra with the maximum/minimum Vertebral Lateral Rotation (VLR) In a junctional zone, the two consecutive vertebrae with the maximum/minimum Intervertebral Axial Rotation (IAR) In an apical zone, the vertebra with the maximum/minimum Vertebral Axial Rotation (VAR) In an apical zone (for thoracic curves only) the two consecutive vertebrae with minimum Intervertebral Sagittal Rotation (ISR)

Junctional Zone

Apical Zone ^"

Intervertebral Sagittal Rotation ISR<0 Intervertebral Sagittal Rotation ISR<0

Vertebral Axial Rotation VAR>0 Vertebral Axial Rotation VAR<0 Vertebral Axial Rotation VAR>0

Vertebral Lateral Rotation VLRX) Vertebral Lateral Rotation VLR<0 Vertebral Lateral Rotation VLR>0 Vertebral Lateral Rotation VLR<0

Intervertebral Axial Rotation IAR<0 Intervertebral Axial Rotation IAR>0 Intervertebral Axial Rotation IAR<0 Intervertebral Axial Rotation IAR>0

•%

y

curve (A)

curve ' (B) ; curve ' (C) J

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3. Results The localization of the characteristic vertebrae (in apical and junctional zones) was the most frequently: • • •

High thoracic curve (A) from C7 to T5 with apex in T2 Thoracic curve (B) from T5 to T12 with apex in T7 Lumbar curve (C) from T12 to L4 with apex in L3

The three dimensional reconstructions and the segmental analysis of the thoracic curve (T4T12, apex in T8) of one scoliotic patient (who also presented a fusion L5/S1) is given Figure 2. The pre operative orientations of the thoracic curves are given in table 1.

ngure /: ire ana post operative three-dimensional reconstruction and segmental analysis of the thoracic curve of one patient

Junction (A/B) InterVertebral vertebral Lateral Axial Rotation Rotation

Apex(B) InterVertebral vertebral Axial Sagittal Rotation Rotation

-32 (10) [-52 -16]

-20(5)

-6(4)

[-29 -11]

[-11 0]

Junction (B/C) InterVertebral vertebral Lateral Axial Rotation Rotation

Pre operative

10(3) 16 14]

29(7) [20 39]

-9(2) [-12 -6]

Table 1 : Vertebral and intervertebral orientations (mean (SD) [range]) for the apical and junctional zones of the thoracic curve.

Concerning the thoracic curve, the pre operative tendency of orientations was 2QJE of Vertebral Axial Rotation with 6& of intervertebral extension in the apical zone and 30JE of Vertebral Lateral Rotation with IOJE of Intervertebral Axial Rotation in the junctional zones.

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Concerning the apex of the high thoracic and lumbar, the mean vertebral axial rotation was 12 ° at both levels. A surgical correction was observed in the three planes, considering the vertebral and intervertebral 3D rotations. The vertebral axial rotation at the high thoracic, thoracic and lumbar apex was corrected with respectively 52%, 60% and 60%. 4. Discussion and conclusion The segmental analysis allows to describe the three dimensional pattern of the scoliosis. Moreover, the vertebral and intervertebral axial rotation can be reliable indices for the structural parts of a scoliotic curve and its severity. The torsion phenomenon was highlighted, with 20 ° of vertebral axial rotation (to the right) in thoracic apex, 12 ° of rotation (to the left) in the counter-curves and 10 ° of intervertebral axial rotation at the junction of the curves. Few authors studied the segmental analysis of the sagittal plane and the segmental kyphosis at the apex. The normal Intervertebral Sagittal Rotation in the T4-T8 area has been reported about +5 ° [14] (for 102 subjects, 13 mean years old) and the scoliotic patients presented, in apical area, -6 ° in average. The kyphosis as well as the lordosis and the Cobb angle, are only a 2D projection of the 3D deformity and are a global evaluation of the scoliosis. As a local evaluation, the vertebral axial rotation has been widely studied, on standing frontal radiographs, CT-scans and intra-operative evaluations. However, the axial rotation and the surgical derotation remains controversial, due to variations of computation methods and application difficulties. With the 3D measurement of the axial rotation proposed in this study (from the stereoradiographic model), the derotation of the high thoracic, thoracic and lumbar apexes were demonstrated with in situ contouring technique (respectively 52%, 60% and 60% of correction). The stereoradiographic methods using NSCP technique 3D provide a quantitative reconstruction of the spine and pelvis that allows the segmental analysis of the deformity. This is a valuable method to evaluate the severity of the scoliosis and quantify the surgical effects. The basic pattern of the right thoracic curve has been measured on ten scoliotic patients and a three dimensional surgical correction has been demonstrated with in situ contouring technique.

5. Acknowledgements The authors express their appreciation to Pr. J. Dubousset and R. Perdriolle for sharing their helpful grasp of scoliosis deformity. The authors also thank the team of the radiological department of the Hopitaux Universitaires - Strasbourg. Funding was received from AGIRS association (Strasbourg, France) and from Eurosurgical (Beaurains, France).

References 1 2 3 4

R. Perdriolle, la scoliose. Maloine (ed.), Paris, 1979. J. Dubousset, Three-dimensional analysis of the scoliotic deformity. In S.L. Weinstein (ed.), The pediatric spine: principles and practice. Raven Press, New York, 1994, pp 479-496. S. Delorme et al., A three-dimensional radiographic comparison of Cotrel-Dubousset and Colorado instrumentations for the correction of idiopathic scoliosis. Spine 25 (2000) 205-210. K. B. Wood et al., Rotational changes of the vertebral pelvic axis after sublaminar instrumentation in adolescent idiopathic scoliosis. Spine 22 (1997) 51-57.

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J. P. Steib and B. Moyses, Etude scannographique de scolioses oper^es, Recueil du GES 24 (1993) 1517. K. B. Wood et al., Rotational changes of the vertebral-pelvic axis following Cotrel-Dubousset instrumentation, Spine 16 (1991) S404-408. B. J. Sawatzky et al., Effects of three-dimensional assessment on surgical correction and on hook strategies in multi-hook instrumentation for adolescent idiopathic scoliosis, Spine 23 (1998) 201-205. C. Lecire Lilloni et al., Optoelectronic analysis of the Cotrel-Dubousset instrumentation, Human Movement Science 18 (1999) 713-724. D. Mitton et al., 3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes, MedBiol Eng Comput 38 (2000) 133-139. J.P. Steib, Spine Contouring System in lumbosacral arthrodesis. In J. Y. Margulies (ed.), Lumbosacral and spinopelvic fixation. Lippincott-Raven, Philadelphia, 1996, pp. 421-430 D. Mitton et al.. Simplified calibration system for stereoradiography in scoliosis. International Meeting of the IRSSD 2000, Clermont-Ferrand, France. I. A. Stokes, Three-dimensional terminology of spinal deformity. A report presented to the Scoliosis Research Society by the Scoliosis Research Society Working Group on 3-D terminology of spinal deformity, Spine 19 (1994) 236-248. W. Skalli et al., Quantification of three-dimensional vertebral rotations in scoliosis: what are the true values?, Spine 20 (1995) 546-553. M. Bernhardt and K. H. Bridwell, Segmental analysis of the sagittal plane alignment of the normal thoracic and lumbar spines and thoracolumbar junction, Spine 14 (1989) 717-721.

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3D Reconstruction and Analysis of the Whole Trunk Surface for Non-Invasive Follow-Up of Scoliotic Deformities Valerie Pazos12, Farida Cheriet12, PhD, Hubert Labelle2, MD, Jean Dansereau12, PhD 'EcolePolytechnique, P.O. Box 6079, Station Centre-ville, Montreal, Canada, H3C3A7 Research Center, Ste Justine Hospital, 3175 Cote Ste-Catherine, Montreal, H3T1C5 Abstract. The purpose of this study was to evaluate the 3D reconstruction accuracy of a new technology that allows the acquisition of the whole trunk and to develop a software to analyse the trunk surface asymmetry. A non-invasive active vision system provides a 3D textured reconstruction of the whole trunk. The analysis system provides the clinician with quantitative indices that characterize the whole external trunk asymmetry.

1.Introduction The first reason that incites the patients and their parents to make inquiries about their disease is the appearance of abnormal asymmetry on the external shape. A non-invasive screening of scoliosis has been the use of the scoliometer to measure the rib hump in forward bending. Unfortunately the lack of precision of the technique lead to a general use of internal indices, such as Cobb angle, measured on X-Rays. Young adolescents with idiopathic scoliosis need intensive follow-up for many years and consequently are repeatedly exposed to ionising radiation. The cancer risks associated with the repeated exposures to ionizing radiation [1,2] during this follow-up could be reduced and the frequency of the visit increased by use of reliable non-invasive follow-up of trunk surface asymmetry. Furthermore, treatments attempt to improve both spinal and surface deformities but internal indices such the Cobb angle do not describe the external appearance [10]. For many years, topographic measurement systems, such as Moire fringe [3, 4, 5], rasterstereography [5, 6], ISIS [7. 8], Quantec [9, 10], laser scanners [11] have been developed in order to quantify external deformations of scoliotic trunks. Most of the developed indices are limited to the back shape analysis. The purpose of this study was twofold: first, evaluate the 3D reconstruction accuracy of a new technology that allows the acquisition of the whole trunk; second, develop software to analyze the trunk surface asymmetry.

2. Materials and methods A non-invasive active vision system composed of three color optical 3D digitizers (Full Body, Inspeck Inc., Montreal) placed around the subject and based on phase shifted Moire projection and active optical triangulation [12] provides a 3D textured reconstruction of the whole trunk (figure 1). The data acquisition requires less than five seconds. With a one per two sampling, the surface counts approximatively 40000 points for the whole trunk.

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Before recording the surface, erasable markers are drawn on anatomical landmarks: vertebra proeminens, dimples of the posterior superior iliac spines, anterior superior iliac spines, spinous processes, inferior angles of the scapulae. During the data acquisition, the subject is asked to hold his breath, standing free with arms slightly separated from the body and looking straight ahead. In order to position the subject with reference to the digitiser coordinate system, heels are placed against a plank and a wooden block separates the feet (figure 2).

a)

b)

Figure 1: Acquisition system (a) and 3D reconstruction of the trunk of a scoliotic subject (b)

To evaluate the reconstruction system, the 3D positions of forty-five markers placed on a mannequin were measured with a Coordinate Measuring Machine (CMM). The mannequin is then repeatedly digitized with the Inspeck system. A point-surface analysis evaluates the geometry of the reconstructed surface. Furthermore, the position of the markers selected on the reconstructed texture was compared to their position measured with the CMM in order to evaluate the quality of the texture mapping process. The reconstructed surfaces of healthy and scoliotic subjects are analyzed from markers on texture and from transversal sections of the trunk. From markers on the surface, the analysis system calculates the antero-posterior and lateral tilting, the shoulder asymmetry and the hip tilting. The system also draws the spinous process line and calculates curvature angles in frontal and sagittal planes. The mean curvature allows the clinician to automatically detect the waist. For each section, back surface rotation is evaluated and four areas are created from two axes based on the length of the chord (figure 2). The angle between these axes quantifies the deformation of the section (for a perfectly symmetric section, the axes would be perpendicular).

Figure 2 : Mean Curvatures (a) and Deformation of sections (b)

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V. Pa;i>s er til. / M) KccnnMruction and Aneil\-\is tit tin Whole Trunk Surface

3. Results and Discussion The geometry based evaluation of the 3D reconstruction of the dummy results on a mean normal distance of 1.21 mm ± 1.02 mm for markers placed on the whole trunk. For the markers on the back the mean distance is of 0.92 mm ± 0.73 mm. The evaluation based on texture results on mean 2D distance of 3.47 mm ± 1.93 mm. The indices of the external geometry of patients are summarized in a clinical form (figure 3).

Figure 3 : Clinical form

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4. Conclusion The proposed system allows a fast recording, requiring less than 5 seconds, of the whole trunk textured surface thus reducing problems related to breathing. From an accurate reconstruction, the analysis system provides the clinician with quantitative indices that characterize the whole trunk external asymmetry. Further work is undertaken to register the bone structure with the external geometry in order to hopefully predict the underlying spinal deformity from trunk deformations.

Acknowledgments This work was supported by the Fundation of the Ste-Justine Hospital and the Natural Sciences and Engineering Research Council of Canada. The acquisition system was financed by the Canadian Fundation for Innovation. References 1.

LEVY AR. GOLDBERG MS. MAYO NE. HANLEY JA. POITRAS B. (1996). Reducing the lifetime risk of cancer from spinal radiographs among people with adolescent idiopathic scoliosis. Spine, 21(13): 15401548. 2. DOODY MM, LONSTEIN JE, STOVALL M, HACKER DG, LUCKYANOV N, LAND CE. "Breast cancer mortality after diagnostic radiography. Findings from the U.S. scoliosis cohort study". Spine 2000; vol.25, pp.2052-2063. 3. SUZUKI N., ARMSTRONG GWD, ARMSTRONG J., "Application of Moire Topography to Spinal Deformity", Moire fringe topography and spinal deformity, Moreland MS., Pope MH., Armstrong GWD., Pergamon Press, 1981, pp 225-240. 4. WONG HK., BALSUBRAMANIAM P., RAJAN U., CHANG SY., "Direct spinal curvature digitization in scoliosis screening - a comparative study with Moire* contourgraphy", in Journal of Spinal Disorders vol.10, n°3,pp 198-192,1997. 5. STOKES IAF., MORELAND MS., "Concordance of back surface asymmetry and spine shape in idiopathic scoliosis", in Spine vol.14, n°l, pp 73-78, J.B. Lippincott Company, 1989. 6. HIERHOLZER E., FROBIN W., "Rasterstereography measurement and curvature analysis of the body surface of patients with spinal deformities", Moire fringe topography and spinal deformity, Moreland MS., Pope MH., Armstrong GWD., Pergamon Press, 1981, pp 267-276. 7. TURNER - SMITH AR., HARRIS JD., HOUGTON GR., JEFFERSON RJ., "A method of analysis of back shape in scoliosis", in Journal of Biomechanics vol. 21, n°6, pp 497-509, Pergamon Press, 1988. 8. WEISZ I., JEFFERSON RJ., TURNER-SMITH AR., HOUGTHON MA., HARRIS MA., "ISIS scanning : a useful assessment technique in the management of scoliosis", in Spine vol.13, n°4, pp 405-408. J.B. Lippincott Company, Philadelphia, 1988. 9. THOMETZ JG., LIU XC., LYON R., LAMDAN R., "Relationship between Quantec measurement and Cobb angle in patients with idiopathic scoliosis", in Journal of Pediatric Orthopedics vol.20, pp 512-516, Lippincott Williams &Willis Inc., Philadelphia, 2000. 10. GOLBERG CJ., KALISZER M, MOORE DP., FOGARTY EE, DOWLING FE., "Surface topography, Cobb angles and cosmetic change in scoliosis", Spine, vol.26, n.4, pp. E55-63, 2001, Lippincott Williams & Wilkins Inc. 11. PONCET P., DELORME S., DUDLEY R., RONSKY J., DANSEREAU J., HARDER J., DEWAR R., LABELLE H., GU P.H., ZERNICKE R., "3D Reconstructions of external and Internal Geometries of trunk using laser and stereographic imaging techniques", in Research into spinal deformities 2, IOS Press, 1999. 12. SONG L.,LEMELIN G., BEAUCHAMP D., DELISLE S., JACQUES D., HALL E.G., 3D Measuring and modeling using digitized data Acquired with color optical 3D digitizers and related applications. Proceeding of The 12th Symposium on 3D Technology, pp 59-77, Yokohama, Japan, Dec. 5-6, 2001.

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Tli H Gn\-ti.s(Ed.t Research into Spinal Deformities 4 IOS Press. 2(102

Assessment of the validity of observing three-dimensional images of the spine using polarising, synchronised techniques Shannon Salvador*, Xiaoping Wang*, Marc Moreau, James Raso, James Mahood, Ryan Currah and Keith Bagnall*. Division of Anatomy* and Department of Surgery, University of Alberta, Edmonton, Alberta, Canada. T6G 2H7 Tel: 780-492- 7094 Fax: 780-492-0462 Email: [email protected] Abstract. Three-dimensional imaging is an emerging technique in radiology. It might be used to help view the spine and assist in improving evaluation of scoliosis. These images are currently computer generated and although very effective are actually optical iflusions. Questions remain as to the reliability and validity of these images which are important considerations when treatment regimens are being developed and surgery contemplated. Using a constructed three-diemnsional image of a box, this study assessed the inter- and intra-reliability of viewing a specific point on this box and also the inter-reliability of identifying the coordinates of this same point. There was good reliability for viewing a single point in the X and Z axes which formed the plane of the computer but there was a 10X decrease in reliability along the Y-axis (depth). This pattern was repeated when considering the relationship between observers to identify the actual coordinates of the same point.

1. Introduction A very practical, potential application of stereographic technology exists with the diagnosis and treatment of scoliosis. A 3-D view of the spine would allow clinicians and surgeons to achieve an idea of the real extent of the curve of a child's spine before attempting surgery. Unfortunately, there are still some problems with application of this technique. It must always be remembered that observation of stereographic images is an optical illusion and although most people can see the created image, it is unknown if people viewing these radio graphs perceive the same image and if the dimensions of what they see are both reliable and valid. The experiments in this paper were conducted to determine the reliability of perceiving a single point on a stereographic image along all 3 axes and whether or not people perceive the point at the same coordinates. 2. Materials and Methods The 12 edges forming the framework of a rectangular box were created from a children's toy, Knex. The size of the box was approximately 4 x 8 inches (Figure 1). At the 8 corners of this framework, coloured push-pins of different colours were added so that the sharp end of the pin was projecting outwards and could provide a precise point for measuring purposes. Parallel photographs, 2 inches apart laterally (left and right images), were taken of the box using a digital camera (Kodak Digital Science DC260

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Figure 1. The actual box that was used to create the 3-D image on the computer screen. Note the pins at each comer of the box. The tips of these pins allowed precise points to be identified for measurement purposes.

zoom camera) using the highest resolution of 1536 by 1024 pixel setting. A white background was used for the photographs to reduce the amount of shadowing and diffuse white light was shone onto the box to reduce the shadowing even further. In this way, the tips of the pins that formed the comers of the box could be seen clearly allowing precise measurements to be made. The two images of the box were incorporated into a software programme (NEOTEK Composer) which allows a 3-D image of the box to be created and manipulated on computer by the operator. The programme allows the position of the 3-D image to be adjusted and so the image of the box was brought 'in front of the screen. In this way, the observer could imagine that the box was in a position in front of the computer screen and could be handled although in actual fact the 3-D image was an optical illusion and did not actually exist. Usually, 3-D images are created so that they are "in the screen" and appear to the observer as if they are looking through a window. This is because the brain has difficulty adjusting to the 2-D interference at the edges of the computer screen and the brain has to handle a 2-D and 3-D image simultaneously. In this case, the 3-D image of the box was centred in the middle of the computer screen away from the edges and so could be positioned as if the box was in front of the screen without creating any problems with interpretation by the observer at the edges of the screen. The observers viewed the image using computer software (Neotek Composer) coupled with liquid crystal shutter glasses that present rapidly-alternating, polarised left and right images that are coordinated with the refresh rate of the computer screen. The screen used was an NEC Multisync 95 monitor (14.5 by 10.75 inches) and was set to a frame refresh rate of 60 Hz. The presentation of the picture was standardized with the glasses set on a pedestal at a fixed distance of 18 inches from the centre of the screen and at a height of 14 inches. An adjustable chin rest was added to the equipment so that the observer could rest their chin while viewing the image and so reduce the effects of physical fatigue. When the observers looked through the glasses, they could see the framework of the box in 3-D as if it was directly in front of them and in front of the computer screen. They could clearly see the tips of the pins that indicated the comers of the box and could move their hands easily and indicate where they thought the tips of the pins on the image were situated in space. An adjustable, small vertical rod that could be placed firmly on the table at any position was used to identify the position of the comers of the box as interpreted by the observer. A pin was securely fastened to the tip of the rod. The tip of this pin and the tip of the pins in the 3-D image could easily be positioned next to each other by the observer. The observers used these rods and pins to indicate the perceived location of the tips of the pins in the 3-D image. The coordinates of any position were determined using the Flock of Birds which is

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a position and orientation measurement system with six degrees of freedom [111. This equipment consists of an electromagnet that has a magnet field of approximately 18 inch radius. The magnetic field was affected by any metal objects in the area and to acquire reliable results, all metal objects had to be moved out of the field while measurements were being taken. The Flock of Birds was calibrated according to the manufacturer's instructions before every trial and the error of measuring the coordinates of a single point was also measured. The Flock of Birds electromagnet transceiver was placed on the right side of the screen and was 12 inches from the screen (Figure 2). The chin rest was adjusted for each observer so that they felt comfortable looking through the glasses at the computer screen in their fixed position. The observers were assessed for their ability to see the 3 -D image of the box by simply asking if they could see it easily, not so easily, or not at all. Questions were asked concerning their visual acuity and previous exposure to 3-D imaging techniques such as shutter glasses used in 3-D movies and stereoscopic pictures seen by crossing the eyes or focusing beyond the picture (as are commonly seen in newspapers). While they were looking through the glasses at the 3-D image of the box, the observers were asked to position the tip of the pin at the top of the adjustable rod to the appropriate depth from the screen and height from the table so that it matched exactly the tip of a selected pin in the 3-D image. This whole procedure was repeated ten times in succession so that an average for the perceived position of the pin could be determined. The location of the pin on the adjustable rod was then measured using the Flock of Birds. Twenty-five observers participated in this experiment and all had binocular vision. Five of the subjects were experienced with viewing 3-D images while twenty of the subjects had never experienced this type of activity. 3. Results The arrangements of the equipment presented no problems to the observers. The chin-rest was comfortable and they felt at ease placing the pins in relation to the image they could see. All the observers reported that they could see the overall image of the box easily but when asked to place the markers and actually identify the position of the pin in space they reported some difficulty in focusing on the object. Table 1 shows the average perceived position and the error of repeating this position for the same pin for each of the 25 observers. The results show that there was good reliability for repositioning the marker in each of the X and Z axes (the plane

Figure 2: The computer screen in relationship to the fixed glasses and electromagnetic transceiver.

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• u*am.*4*u .««*«« Figure 3: The mean perceived location and positional error for one point on the image for observer #1 presented in X, Y, Z format. X axis = horizontal axis, Y axis = depth from the transceiver to the screen, Z axis height above the table. The mean values and errors were calculated from 10 trials of the experiment. Table 1: The mean perceived average distance from the transceiver and error of positioning of one point on the image for each of the 25 observers presented in an X, Y, Z format. X axis = horizontal, Y axis = depth from the screen, z axis = height from the table. The mean (value - in.) and error (S.D.) were calculated from 10 separate trials for each observer. The minus sign associated with values in the Z axis relates to the position of the transceiver.

created by these two axes is parallel to the computer screen) with the average standard error of measuring being approximately 1%. In contrast, the reliability of positioning in the Y axis was much less in 40% (10/25) of the observers with the standard error of measuring being approximately 5%. An example of the relative discrepancies in error of positioning in each of the three axes for one observer (#1) is shown in Figure 3. The pattern of decreased reliability in the Y axis was also expressed in the actual positioning of the marker. While the true position of the pin could not be determined because it was dependent on the perception of the observer, nevertheless most observers positioned the marker approximately 9 inches from the transceiver in the X axis (range 8.68 in. -9.41 in.) and -9 in. in the Z axis (range -8.96 in. —9.70 in.). Again, in sharp contrast, the values in the Y axis were much more variable ranging from 4.56 in. to 16.3 in. These results suggest that there were considerable differences among the observers in their ability to perceive depth in 3-D in the computer-created image. Figure 4 shows the positions of the perceived pins for each of the 25 observers. There is clearly a wider discrepancy in the Y axis than along either of the other two axes.

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.x
Figure 4: The mean perceived location of one point on the image for observers 1-25 presented in X, Y, Z format. X = horizontal, Y = depth from the transceiver to the screen, Z = height from the table. The means were calculated from 10 trials of the experiment for each observer. The error bars were omitted for clarity. Note that the axes do not have the same scale. The variation along the Y axis is much greater in absolute terms than perhaps this graph initially indicates.

4. Discussion The results of this study have shown that use of new 3-D technology for looking at images needs to be made with considerable caution. There appear to be differences in ease with which computer-generated, 3-D images can be perceived by an observer but even when the images can be seen there are large discrepancies in relation to the coordinates of specific points on the perceived object. Although most people report being able to see the 3 -D image that has been created, their perception of the image differs greatly. Perhaps this is not too surprising because it must be remembered that the computer-generated image is really an optical illusion. Perception of the image in a plane that is parallel to the surface of the computer screen (combination of X- and Z-axes) is the best in terms of comparisons both for the same individual and between different individuals, but there are large discrepancies when the distance from the computer screen (Y-axis) is being considered. Perceptions in the plane parallel to the computer screen are relatively small but those along the Y-axis can vary by a multiple of three. Acknowledgements. The authors wish to thank the Edmonton Orthopaedic Research Association for providing funds for this project. References 1. Roentgen, W. (18%). A new kind of ray, a preliminary communication, Electrician. 2. Thomson, B. (18%). Stereoscopic roentgen pictures. Electrical Engineer, 21, 256. 3. Abrahams, N.J., Savin, M.B. (1971). Selections from the scientfic correspondence ofElihu Thomson, MIT Press, Cambridge, Mass. 4. Kasahara, T. et al. (1969). Stereo-Radiography using holographic techniques, JJA.P., 8, No.l, 124-125. 5. Groh, C., and, Kock, M. (1970). Three-dimensional display of x-ray images by means of holography, Applied. Optics, 9, No.3,775-777. 6. Butler, P.P., Conway, B.J., Suleiman, 0.11., Showalter, C.K. (1985). Chest radiography: a survey of techniques and exposure levels currently used, Radiology, 156, 533-536. I. Inoue, T. (1995). Stereoscopic 3D display in virtual reality. Journal ofHuman Sciences, 7/2, 22-31. 8. Inoue, T., Kawai, T. and Noro, K. (19%). Performance of 3-D digitizing in stereoscopic images. Ergonomics, 39, 1357-1363. 9. Todd, J.T., Norman, J.F., Koenderink, JJ., Koppers, A.M.L. (1997). Effects of texture, illumination, and surface reflection on stereoscopic shape perception. Perception, 20,733-754. 10. Sun, J.Y., Perona, P. (1995). Preattentive perception of elementary three-dimensional shapes. Vision Research, 36, No.16, 2515-2529. I1. Ascension Technology Corporation (1995). The Flock of Birds Installation and Operation Guide, Burlington, Vermont.

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Growth, development and puberty indicators on spinal growth Dr Peter H Dangerfield The University of Liverpool Liverpool UK

1. Introduction Growth of the physical dimensions of the body is a regulated and complex process which has been studied and recorded over many years [1]. It is controlled by factors which include endocrine hormones such as those produced by the pituitary and other glands [2]. While growth hormone itself regulates muscular and skeletal growth, equally important are the roles of thyroid hormones, essential for CNS development, insulin for its glucose and amino acid effects and parathyroid hormone for its role in calcium metabolism. The gonads produce a range of hormonal factors which are essential for sexual changes including puberty and the onset of menstruation. Growth hormone (GH), insulin-like growth factor I (IGF-I), testosterone and oestrogen all have an effect on protein synthesis and degradation and lipolysis, affecting body composition and bone calcium fluxes in young children and adults. The term 'puberty1 is applied to a series of events marking the transition from childhood to adulthood, spread over several years, with a sequence and timing which varies from person to person [3]. Sexual development commences at the fetal stages of life when the gonads undergo differentiation into female and male, followed by maturation during the postnatal development which culminates in puberty. The events establishing puberty commence well before any physical signs are present and are driven by pulsed release of gonadotrophicreleasing hormone (GnRH) from the hypothalamus in the brain [4]. The presence of these hormones can be detected as early as 7 to 8 years of age in girls and about a year later in boys. The rate of progress of the changes of puberty are independent of the time at which it begins, with its duration varying from about 2 to 4V2 years. About 50 per cent of children complete the sequence in 3 years, and virtually all do so in 5 years. The early developing child is not necessarily the first to reach sexual maturity. The process of puberty is driven by the release of hormones from the hypothalamicpituitary-gonadal system. The pulsed release of the hypothalamic gonadotrophic-releasing hormone occurs initially during the night but increasingly takes place throughout the 24 hour period. A marked influence on the whole process has been attributed to the nutritional status of the individual. This has led to the concept of early childhood environmental influences on puberty which may in turn have an effect on fertility in later life. 2. Puberty in boys The earliest sign of puberty in boys relates to the growth of the testicles, which may occur as early as 9 years or as late as 15 years [2]. As the process continues, mitotic figures abound in the seminiferous tubules, spermatogenesis begins, and testosterone appears in the urine. The variations in the timings of these changes. Clinically, it is useful to remember that whatever his age, a boy in the early stages of sexual development has usually not begun his maximal rate of growth, and will subsequently add considerably to his height.

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3. Puberty in girls The ovaries increase in size as a first sign of puberty, and the levels of oestrogens excreted in the urine give an indication of ovarian activity. The first external sign of female puberty is the commencement of enlargement of the breasts (termed thelarche). This precedes the maximal velocity of the adolescent spurt, beginning between 9 and 13 years of age. Internally, the vaginal epithelium thickens and accumulates glycogen and there are changes to the bacterial flora within the vagina as its fluids become more acid. Menarche (the onset of menstruation) is the main indicator of sexual maturation but occurs after the adolescent growth spurt in most girls. The average age of menarche has been decreasing in industrialised countries for the last 150 years [5] although it is now appearing to stabilize [6]. 4. Hormonal changes related to puberty As already noted, the trigger for the primary stages of sexual maturation and puberty is the increase in GnRH produced by the hypothalamus. Recent research has indicated that this GnRh production may be dependent on leptin release in adipose tissue [7]. Leptin is a type-1 cytokine which as been shown to aid regulation of body weight and energy homeostasis and is closely linked to the reproductive processes in both animals and humans. It regulates ovarian development and steroidogenesis and serves as a primary signal initiating puberty, suggesting that it is a permissive regulator of sexual maturation [8]. It has also be shown that peripheral leptin concentrations are dramatically higher in females than in males throughout life and it is interesting to speculate whether this is might be an important aetiological factor in AIS. At the same time as production of GnRH increases, the pituitary gland releases follicle stimulating hormone (FSH) and lutenising hormone (LH), both of which result in gonad growth and development as well as triggering gametogenesis and subsequent sex hormone release. 5. Growth and puberty With the variability of the onset of puberty in both sexes, the pubertal influence on growth is also marked, resulting in a highly variable auxological process. The rapid increase in growth rate associated with puberty is called the adolescent growth spurt and its timing must be highly influential on the nature of scoliosis if it is detected. Within the skeleton, an increase bone deposition occurs. Testosterone, produced in the maturing testis and adrenal cortex in the male, but only in the females adrenal cortex, affects muscle development. Females experience an increase in oestrogen production, and, as this promotes closure of epiphyseal plates, it plays a role in halting growth after puberty. Growth ceases before the onset of menarche. Oestrogen and androgen also modulate calcium fluxes, enhancing calcium absorption and retention, important for bone calcium metabolism. Calcium intake is also closely related to skeletal development. While there are low to moderate relationships between childhood and adolescent and adult physical activity and health, the trends emphasize the importance of a lifestyle of regular physical activity during childhood and adolescence which continues into and throughout adulthood for the health and well-being of the individuals and populations [9; 10]. Calcium and other nutritional deficits can result from self-induced restriction of energy intake that, if occurring during puberty and adolescence, will affect individual growth patterns, raising concerns that osteoporosis may be a problem in later life. With

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marked energy expenditure of training and competition in sport, and with the self-selection of certain body types, it becomes difficult to identify the individual factors responsible for the slow linear growth of some adolescent athletes [11]. Physical training for sport and ballet can result in amenorrhoea and a delayed menarche in females. Conditions such as anorexia nervosa illustrate extremes of the diet restriction effect. Individuals with anorexia nervosa have increased risk of low bone density if the malnutrition commences early in puberty [12]. There is also reduced lean body mass and impaired ovarian function. However, the role of individual genetic make-up in determining calcium absorption and bone turnover associated with dietary and other environmental effects must not be overlooked. Growing cartilage is also important in the changes of puberty. The precursor cell division in growing cartilage ultimately determines human height, the lengths of the spine and limb bones, the alignment of joints, spines and limbs, and the ratio of spinal length to limb length. It is unclear what controls these processes although genetic and hormonal factors are important as well as contributions from biomechanical influences such as gravity and muscular forces [13]. Other changes occurring at puberty affect fat deposition. At birth, both sexes have about 10 to!2% body fat which rises in pre-puberty to about 16-18%. However, postpubertal girls have around 25 % body fat due to their having higher serum oestrogens and the growth changes, which lead to their hips widening and extra fat storage. In contrast, post-pubertal boys have only 12-14% body fat. Interestingly, most athletic females, post puberty, tend to maintain a body fat level at around 18%. These observations suggest a need to collect information on diet and lifestyle in children today, which might be useful in scoliosis where a growth disturbance is often encountered. 6. Clinical recording of growth. The clinical importance of the accurate assessment of height and other anthropometric measures including the skeletal measurement of maturity is a key to the understanding of the growth processes associated with puberty and the potential progression of scoliosis. Such assessments should include study of body asymmetry [3] and the routine calculation of the Body Mass Index (BMI wt/ht2). Growth charts are available for many populations such as height and weight against age and height velocities (see [14] for a review of growth charts). BMI calculation is used to identify children at risk for being overweight as they get older and can be helpful in a scoliosis setting. There are also methods available to assess the age at menarche although retrospective data collection is recognised as unreliable [15]. The onset of puberty in humans also coincides with the final regressive event in the central nervous system with the elimination of 40% of neuronal synapses. This links a growth component of puberty to a neurological factor and this forms a basis for the NOTOM concept of adolescent idiopathic scoliosis (neuroendocrine control) [16]. The tall, ectomorphic girl who develops adolescent idiopathic scoliosis early in puberty requires close study to establish whether any features she possesses can be identified as markers for understanding the aetiology of the condition, in the context of current developments relating to puberty. 7. Conclusion. In this short review, much detail of current research and ideas relating to puberty cannot be discussed in depth. However, the research into hormones and signalling agents is progressing rapidly, and this, combined with known genetic markers for some of these factors, might find application in the study of scoliosis, a multifactorial condition in which

P.H. Dangerfield / Clnncrh. Development and Pithen\ Indicator* on Spinal (imwih

the spinal involvement is but one feature of a complex problem. research is needed to test these ideas.

Clearly much more

References 1

2 3

4

5 6 7

9 10 11. 12

13 14

15

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J. Karlberg, The human growth curve. In: The Cambridge Encyclopaedia of Human Growth and Development. Ed: S. J. Ulijasek, F. E. Johnston M.A. Preece, Cambridge University Press, Cambridge UK. Pp 108-115 1998. P.H. Dangerfield, Human Growth after Birth, Oxford University Press, Oxford UK 1998. P.H. Dangerfield, Asymmetry and growth. In: Anthropometry: the individual and the population. Ed: S. J. Ulijasek, C.G.N. Mascie-Taylor, Cambridge University Press, Cambridge UK. Pp 7-29 1994. P. T. Ellison, Sexual maturation, In: The Cambridge Encyclopaedia of Human Growth and Development. Ed: S J Ulijasek, F E Johnston MA, Preece, Cambridge University Press, Cambridge UK Pp 227-229 1998. P. Eveleth Menarche, In: The Cambridge Encyclopaedia of Human Growth and Development. Ed: S J Ulijasek, F E Johnston MA, Preece, Cambridge University Press, Cambridge UK. Pp 228 1998. D. Mul, A.M. Fredriks, S. van Buuren, W. Oostdijk, S.P. Verloove-Vanhorick, J.M. Wit, Pubertal development in The Netherlands 1965-1997, Pediatric Research 50(4):479-86, 2001. J.C. Sabogal, L. Munoz, Leptin in obstetrics and gynecology: a review, Obstetrical & Gynecological Survey 56 (4):225-30, 2001. g M.C. Henson and V.D. Castracane, Leptin in pregnancy. Bid Reproduction. 63(5):1219-28,2000. R.M. Malina, Physical activity and fitness: pathways from childhood to adulthood. Am J Human Biol 13(2): 162-72, 2001. J.J. Anderson, Calcium requirements during adolescence to maximize bone health, J Amer Coll Nutrit 20(2):186S-191S, 2001. A.D. Rogol, P.A. Clark, J.N. Roemmich, Growth and pubertal development in children and adolescents: effects of diet and physical activity. Am J Gin Nutrit 72(2 Suppl):521S-8S, 2000. J.M. Turner, M.K. Bulsara, B.M. McDermott, G.C. Byrne, R.L. Prince, D.A. Forbes, Predictors of low bone density in young adolescent females with anorexia nervosa and other dieting disorders, Int J Eating Disorders 30 (3):245-51 2001. H.M. Frost, E. Schonau, On longitudinal bone growth, short stature, and related matters: insights about cartilage physiology from the Utah paradigm, J Pediatric Endocrinology 14(5):481-%, 2001. TJ Cole, Statistical constructs of human growth: new growth charts for old. In: Anthropometry: the individual and the population. Ed: S. J. Ulijasek, C.G.N. Mascie-Taylor Cambridge University Press, Cambridge UK. Pp 78-98 1994. P Eveleth, Assessment of age at menarche. In: The Cambridge Encyclopaedia of Human Growth and Development. Ed: S J Ulijasek, F E Johnston MA, Preece. Cambridge University Press, Cambridge UK. Pp 62 1998. RG Burwell and PH Dangerfield 2002X, Neuromuscular concepts and adolescent idiopathic scoliosis. In: Research into Spinal Deformities 4 (Ed: T Grivas.) XX-XX 200X. Amsterdam: IOS Press.

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Scoliosis Study Using Finite Element models Carl-Iiric Aubin Ph.D. 7 - Canada Research Chair "CAD Innovations in Orthopedic Engineering ", Mechanical Eng. Dept., Ecole Polytechnique, PO Box 6079, St. Centre-ville, Montreal (Quebec), Canada H3C3A7 2 - Research Center, Sainte-Justine Mother-Child University Hospital, 3175 Cote-SainteCatherine Rd, Montreal (Quebec), Canada H3T1C5 Abstract. Finite element models have been used for many years to study scoliosis biomechanics. This paper presents some of the work done in our institution over the last decade in this area. It covers the simulations of scoliosis treatment (orthotics, surgical instrumentation), muscle and control, as well as the growth process. The models presented in this paper are of clinical interest because they have the capacity to simulate an unlimited number of variables to investigate scoliosis biomechanics. Current developments are directed toward the integration and validation of specific models (muscle, control, and growth modeling) into a unified refined model of the trunk, thus allowing a more complete understanding of scoliotic spine pathomechanicsms, as well as to predict in advance what would be the resulting shape of the spine in response to the application of a treatment

1. Introduction Finite element models have been developed and used for many years to investigate the trunk biomechanics. In summary, these models have as inputs the geometry of the patient's trunk, estimates of the flexibility and other mechanical properties, the boundary conditions (forces and displacements applied on the model), and the definition of the parameters of the intended simulation. The outputs are the predictions of the simulation (displacement) and the mechanical effects (i.e. stress, strain, velocity, force, etc.) on the trunk. The utilization of such models was quite useful to study the scoliotic deformation process and its treatment. This paper presents some of the work done in our institution over the last decade in this area. 2. Studies of scoliotic trunk biomechanics and brace treatments Simulations of Boston brace treatment were realized to study the biomechanics of conservative treatment in idiopathic scoliosis [1,2]. Pressures generated by the brace on the patient torso were measured by thin pressure sensors, and were used as input to the personalized finite element model built using a multi-view radiographic reconstruction technique. The simulations were compared to the reconstructed geometry of the patients wearing their brace by means of several geometrical and clinical indices. The numerical simulations showed the feasibility and validity of such modeling approach, and pointed out the major influence played by the boundary conditions, thoracic pads and abdominal pressures. This way of modeling is quite a simplification of real bracing. It is questionable as bracing is represented using external loads instead of reaction forces (that depend on the relative flexibility and geometry of the brace and trunk). To overcome this limitation, an explicit personalized representation of the brace (hexahedral elements) and its interface with the torso (contact elements) recently was developed (Figure 1), with promising preliminary results [3]. The same finite element model was used to investigate the coupled mechanisms between the scoliotic spine and the rib cage subjected to loads corresponding to a brace [4].

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Single forces were applied at different locations on the thorax to simulate orthotic load components. This study demonstrated the existence of coupled motions between the spine and rib cage (deformations of the spine in other directions than the load application onto the thorax). It showed that the loads applied on the posterior rib hump are associated to an important reduction of sagittal curvatures (flat back), and to a lateral shift of the thoracic spine toward the convex side thus increasing the spinal curve in the frontal plane. It suggests that coupled mechanisms should be considered in the design of orthotic treatment of scoliotic deformities. Finite element modeling was used to test novel orthotic approaches and investigate their effect [4]. An original concept consisting in applying differently the loads on the thorax was proposed and investigated. It was demonstrated that it was mechanically possible to improve current brace design and correct in 3D the scoliotic deformities. Optimization of brace treatment was realized using this finite element model, to find best possible loading patterns to correct the scoliotic deformities in 3-D [5]. Three generic forces modified in position and orientation at each iteration were applied on the trunk and the resulting geometry was used to calculate a cost function that considered coronal and sagittal offsets from a "normal spine", as well as the rib hump. Optimal forces differed depending on patient shape but were mostly located on the convex side of the curve (postero- and antero-laterally). This study pointed out the usefulness of such biomechanical modeling and optimization approach to develop better individualized brace design. However, these are considered preliminary investigations, and the brace design work needs to be continued to address its clinical validity.

Figure 1: FE model of the brace treatment represented by an explicit modeling of the

Figure 2: Flexible multi-body model of the CD instrumentation at 3 steps of the surgery

3 Simulations of surgical treatments The finite element model of Stokes and Gardner-Morse [6] was adapted to investigate the biomechanics of spinal instrumentation. Four steps were used to simulate the surgical maneuvers of the Cotrel-Dubousset instrumentation: 1) installation of hooks/screws on instrumented vertebrae; 2) attachment of the hooks/screws on the rod (translation step); 3) rod rotation, 4) hooks/screws lock up and elastic spring back. This was simulated on 15 different cases. Model's geometry was personalized using patient's 3-D reconstruction

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built from pre-operative X-rays, and results were compared with post-surgical geometry. Most simulations of surgical maneuvers generally showed good agreement (on average) with measured effects of surgery in the frontal plane. However, in the sagittal and transverse planes, the response was dependent on model's boundary conditions, motion segments' mechanical properties and instrumentation variables [7]. In order to better represent the mechanism of the instrumentation system, the large displacements and the stiffness difference within model components, a flexible multi-body (kinematic) model recently was developed [8]. This model includes flexible elements to represent each motion segment and kinematic joints and sets to model the instrumentation (Figure 2). The intra-operative instrumentation maneuvers were simulated using four similar steps. Finite element modeling is also used to simulate other instrumentation systems (i.e. Colorado2, Eclipse, etc.) and surgeries. Grealou et al. [9] analyzed different rib surgery procedures (side, location, length, and number of ribs to resect or to graft), to investigate their biomechanical effect (corrective forces transmitted to the spine, thorax shape modification, etc.), and to test corrective mechanisms involving the rib cage. Current modeling of scoliosis surgery requires more refinements, especially to formulate the models, specify the inputs, and improve analysis tools. The interesting applications still remain to come. 4 Integration of muscles and motor control The finite element model was refined to incorporate trunk muscles and central commands using the A, model of Feldman [10]. Eight muscle groups have been introduced, represented by 160 fascicles that join the attachment points in straight lines. Muscle geometry and physiological cross-sectional areas were adapted from other studies [11]. The equilibrium point hypothesis (A, model of Feldman) was used to simulate the control process generating trunk posture or movement. The control structure is based on a generalized formulation of the A. model to multi-muscle and multi-degree of freedom systems. It was supposed that, in absence of co-contraction, threshold lengths A, of each muscle are specified, and this set of threshold lengths is associated with a particular referent body configuration. Change in posture (movement) is produced by changing the initial to a final referent body configuration resulting in a change in the threshold lengths for all muscles. This model was used to simulate a lateral bending for a scoliotic subject by eliciting appropriate changes in the central commands [10]. Activity was mainly obtained in the ipsilateral external and internal obliques in accordance with known functional anatomy, previously modeled changes in length and reported EMG data for these muscles. This study shows the feasibility of considering a neurophysiological formulation into a finite element model in analyzing trunk behavior, and in exploring different muscle recruitment principles. End point development of this approach may provide a simulation tool to study the role of central commands deficits in eliciting the pathomechanisms of scoliotic deformities. 5 Simulation of growth and remodeling Recent work was initiated to integrate the growth and remodeling processes of the scoliotic spine into the finite element model [12]. The intervertebral structures of the anterior spine were adapted to integrate Hueter-Volkman principles, as well as the global growth process of the vertebral bodies. The simulation is made using an iterative cyclic process. An initial dysfunction in the spine (force disequilibrium, growth perturbation, shape asymmetry, or a combination of these parameters) can be used as input into this cycle. At each iteration, a small increment of growth is applied (uniformly or at specific

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regions of the spine), and the geometry of the vertebrae is updated (node relocation technique). Then, the external loads are applied, the new stress distribution and the resulting effects of growth and remodeling on each vertebral body are calculated, and are used to update (node relocation technique and stresses reset) the local geometry of the vertebrae (wedging), which in turn has an impact on the global spinal shape. This process is repeated until the end of the desired growth or the number of steps is reached. Different pathogenesis hypotheses of AIS were represented using an initial geometrical eccentricity at the thoracic apex to trigger the self-sustaining deformation process. Overall, the developed model adequately represents the self-sustaining progression of vertebral and spinal scoliotic deformities. The results support the hypothesis of a prime lesion involving the precarious balance in the frontal plane, which could concomitantly be associated to a hypocyphotic component. They also suggest that coupling mechanisms were involved in the deformation process. 6. Discussion Finite element models presented in this paper are of clinical and practical interests because they provide the opportunity to simulate an unlimited number of variables to investigate scoliosis biomechanics. Current developments are directed toward the integration and validation of specific models (muscle, control, and growth modeling) into a unified refined model of the trunk, thus allowing a more complete understanding of scoliotic spine pathomechanicsms, as well as to predict in advance what would be the resulting shape of the spine in response to a treatment. However, we should be aware of their current limitations, and understand their implications when using model's results. The development of a finite element model requires a large amount of data for its definition. The more refined a model, the more parameters are needed which are more complicated to obtain. Patient-specific properties are difficult to obtain, and may affect the simulation results. Nevertheless, these variations may be interpreted by conducting several simulations using the possible bounding values. We have found that boundary conditions and simulation parameters (displacements or forces applied on the model to represent the connection with its environment and the simulated phenomena) have a most consequential effect on the simulation than mechanical properties. We are still limited to the number, the availability and the accuracy of the data needed to implement the model, and most importantly the complexity of the phenomena to be simulated, which explains current oversimplification of the models and simulations. Knowing these limitations, finite element models should not be used beyond their scope of validity and application limitations. They should be used in combination with other kind of studies (clinical studies, in vitro and in vivo laboratory experiments, etc.). Progress in scoliosis biomechanics is likely to be made when limitations of biomechanical models and other methods are kept clearly in perspective.

7. Acknowledgements I would like to acknowledge the work of principal collaborators (H. Labelle, I. Stokes, J. Dansereau) and graduate students who participated in the development of the models (Y. Petit, D. Peri6, M. Lacroix, I. Villemure, M. Beausejour, F. Poulin, Y. Lafon, D. Gignac, L. Grealou). One of the preliminary models was developed in collaboration with ENS AM. This research was funded by die Natural Sciences and Engineering Research Council of Canada (NSERQ, the Medical Research Council of Canada (MRC), the Quebec's Research Council (FCAR) and the Medical Research Council of Qu6bec (FRSQ).

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References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

C.E. Aubin et al. Biomechanical simulation of the Boston brace effect on a model of the scoliotic spine and thorax (in French). Ann. Chir. (1993) 47:9, 881-887. [C.E. Aubin et al. Personalized Biomechanical Simulations of Orthotic Treatment in Idiopathic Scoliosis, J Orthop Res (2002, in revision). [D. Perie et al. Personalized Biomechanical Modeling of Boston Brace Treatment in Idiopathic Scoliosis, IRSSD 2002. [C.E. Aubin et al. A study of biomechanical coupling between spine and rib cage in the treatment by orthosis of scoliosis, Ann Chir, (1996) 50:8,641-650. [D. Gignac et al. Optimization method for 3D correction of scoliotic deformities using a finite element model, European Spine J, (2000), 9:3,185-190. [M. Gardner-Morse, I.A.F. Stokes. Three-Dimensional Simulations of the Scoliosis Denotation Maneuver with Cotrel-Dubousset Instrumentation, J. Biomechanics (1994) 27:177-181 [I.A.F. Stokes et al.: Biomechanical simulations for planning of scoliosis surgery, Research into Spinal Deformities II, IOS Press, vol. 59,343-346,1999. [F. Poulin et al. Biomechanical modeling of instrumentation for the scoliotic spine using flexible elements: a feasibility study, Ann Chir, (1998) 52:8, 761-7. L. Grealou et al. Rib cage surgery for the treatment of scoliosis: a biomechanical study of the correction mechanisms, J Orthop Res (2002; in press). [M. Beausejour et al. Simulation of lateral bending tests using a musculoskeletal model of the trunk, Ann Chir (1999) 53(8):742-750. [Stokes IAF et al. Lumbar spine maximum efforts and muscle recruitment patterns predicted by a model with multijoint muscles and joints with stiffness, J Biomech (1995) 28, 173-186. I. Villemure et al. Simulation of progressive deformities in adolescent idiopathic scoliosis using a biomechanical model integrating vertebral growth modulation, J. Biomech Eng. (2002, in press)

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The Role of Muscles and Effects of Load on Growth Ian Stokes and Mack Gardner-Morse Department of Orthopaedics and Rehabilitation University of Vermont, Burlington, VT 05405, USA

Abstract: If mechanical modulation of growth explains progression of scoliosis during adolescent growth, two elements of the 'vicious cycle' must be quantified. Firstly we must identify the magnitude of the asymmetrical loading imposed on the spine as a function of the scoliosis curve magnitude. Secondly, we must characterize the growth response of vertebrae and remodeling response of discs to this asymmetrical loading. Animal models are helpful to quantify the former, and extrapolation to the human spine should be possible once the parameters that influence the growth modulation response have been identified. Direct measurement of spinal loading is not currently feasible, so analytical modeling to estimate plausible loading states is required. Our simulations using a model that represents the lumbar spinal musculature and a spine with increasing degrees of spinal curvature suggests that there is a range of muscle activation strategies that may predispose to progression by the 'vicious cycle' mechanism, but other strategies can load the spine uniformly, or even reverse the asymmetrical loading that would lead to progressive deformity. However, the latter strategies have a physiological 'cost' associated with increased muscle stress and increased spinal loading.

1. Introduction The notion that progression of spinal deformity is mediated through mechanical modulation of growth, producing asymmetrically wedged vertebrae is intuitively attractive. It provides a supposed basis for scoliosis management with bracing, etc. The 'vicious cycle1 theory of scoliosis progression proposes that scoliosis causes loading of the spine that is asymmetrical in the coronal plane, and that vertebral growth and disc remodeling respond to the chronic presence of these asymmetrical forces. While qualitatively plausible, the 'vicious cycle' requires quantification of two crucial components: the magnitude of the loading distribution across discs and vertebral growth plates, and the growth response to mechanical loading of these structures. This paper focusses on quantifying the first of these presently qualitative elements. While it seems intuitively reasonable that coronal plane curvature (scoliosis) would produce coronal plane asymmetrical loading of the spine, this has not been proven. Direct measurement of the loading asymmetry in the spine during functional activities has not been attempted, since there is no available instrumentation capable of providing this information in live humans with scoliosis. Therefore, mathematical modeling was used in this study to estimate lumbar spinal loading as a function of the external effort of the modeled subject, the muscle forces required for equilibrium, and the trunk geometry including the degree of scoliosis. The trunk muscle activation strategy in persons with and

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without scoliosis is not known. In these simulations we used an optimization approach in which the muscle activation strategy had the objective to achieve spinal loading that either decreased or increased the asymmetry of vertebral loading, or did not take vertebral loading asymmetry into account. The goal of this study was to find whether there are muscle strategies that can produce coronal-plane symmetrical loading of the spine with scoliosis, and also to find the plausible magnitude of the spinal loading asymmetry for muscle strategies that do not take into account the loading symmetry of the spine. Furthermore, we investigated the physiological cost in terms of muscle forces and spinal loading of adopting a strategy that loads the spine symmetrically. 2. Methods A previously reported mathematical model of the lumbar spine and its musculature [1,2] was used as the basis for this study. The model represented six motion segments of the lumbar spine (T12-L1 through L5-S1), and the muscles that cross these levels. The thoracic spine was not included, in order to avoid additional variables associated with the ribs. The skeletal and muscular geometry, and motion segments represented as beam elements, was based on that reported in Stokes and Gardner-Morse [1,2]. The initial spinal geometry (with sagittal plane curvature, but no scoliosis) was then transformed in order to produce five idealized scoliosis curves with increasing scoliosis magnitudes of 13, 26, 38 and 51 degrees Cobb angle, apex at L-2, as was done by Stokes [3]. For each deformed spine shape, the muscle end points were repositioned according to displacements and rotations of their associated vertebral attachment sites.

Figure 1: Model geometry (vertebrae and lines of action of muscles) for the model that represented a lumbar scoliosis magnitude of 38 degrees Cobb, apex at L-2. The modeling problem of determining the muscle forces associated with any given external load is statically indeterminate, since the number of muscles crossing the lumbar spine exceeds the number of intervertebral degrees of freedom. Four muscle activation strategies were analyzed. In Strategy 1, the indeterminate problem was solved for the unique case of maximum external efforts. These were calculated for the 58 degrees Cobb scoliosis geometry, and for positive and negative external moments generated about each

/. Stokes and M. Gardner-Morse / The Role of Muscles and Effects of Load on Growth

of the global axis directions (flexion, extension, left and right lateral bending, clockwise and counter-clockwise axial rotation) in turn. Then simulations were performed for two loading states: 50% and 75% of the maximum efforts calculated previously. For the submaximal efforts, each muscle activation strategy was defined by an objective function in a non-linear optimization. At each level of effort (50% and 75% of maximum), simulations were performed for three different muscle activation strategies. In Strategy 2, the objective was to minimize the sum of squares of the muscle stresses, as proposed by Hughes et al. [4]. In Strategy 3, the objective was to minimize the sum of the squares of the lateral bending moments at all motion segments of the lumbar spine, in addition to minimizing the sum of squares of the muscle stresses. Then, if the moment objective is met, the loading distribution across the vertebrae can be considered to be uniform (the 'follower load' as described by Patwardhan et al. [5]). In Strategy 4, the objective was to maximize the curve correcting moment at the two motion segments adjacent to the curve apex (L-2). As in Stokes et al. [1], bounds were placed on muscle forces and intervertebral displacements according to physiologically plausible limiting values. 3. Results Strategy 1 predicted maximum external effort moments of 56 and 66 Nm (flexion and extension), 72 Nm lateral bending, and 20 Nm axial rotation at the 51 ° Cobb curve magnitude. At 50% and 75% of these moments, the Strategy 2 simulations (minimize muscle stresses) predicted spinal loading that was offset up to 12 mm at the L2-3 level (apex). This loading is compatible with growth modulation that would increase the scoliosis according to the 'vicious cycle' theory. Strategy 3 (minimize lateral bending moments) predicted zero intervertebral lateral bending moments in all cases ('follower load'). However, the muscle recruitment pattern that achieved this 'follower load' state required greater muscle stresses (Figure 2), and correspondingly greater intervertebral compression force magnitudes. In Strategy 4, a correcting moment was achieved under all simulated conditions at the apex, and this was associated with asymmetrical loading of the vertebrae that would reverse the 'vicious cycle'. However, to achieve this, the mean muscle stresses and associated spinal forces were increased relative to Strategy 2 values by about twice as much as for Strategy 3.

i Figure 2: The increase in mean muscle stress that was required to achieve a 'follower' loading of the spine (Strategy 3), relative to that for Strategy 2 (minimize muscle stress only). MX is lateral bending moment, My is flexion/extension, and Mz is axial rotation moment.

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4. Discussion A muscle activation strategy that minimized the lateral bending moments was able to reduce these moments to zero, thereby creating a loading state that would produce no scoliosis progression according to the 'vicious cycle' theory. This loading condition is similar to the 'follower load' [5] where the load takes the same path relative to the vertebrae as the spine deforms. Thus the follower loading imposes minimal or zero moments about the spinal motion segments. Furthermore, it was possible to simulate a muscle activation strategy (Strategy 4) that would produce a correction moment and a loading asymmetry compatible with reversing the presumed 'vicious cycle' mechanism of curve progression. One can speculate that different individuals with scoliosis adopt differing muscle activation strategies, and that some strategies predispose to a spinal loading state that produces substantial progression during growth, while others do not. This paper demonstrates that there are multiple plausible loading states, resulting in a wide range of lateral bending moments in the motion segments; hence differing degrees of asymmetrical loading of the vertebrae and discs. Some loading conditions might cause scoliosis progression, while others would not. References: 1

2 3 4 5

Stokes and Gardner-Morse. Lumbar spine maximum efforts and muscle recruitment patterns predicted by a model with multijoint muscles and joints with stiffness. Journal of Biomechanics 1995; 28(2): 173-186. Stokes IAF, Gardner-Morse M: Quantitative anatomy of the lumbar musculature. Journal of Biomechanics 1999, 32: 311 -316. Stokes IAF: Analysis of symmetry of vertebral body loading consequent to lateral spinal curvature. Spine 1997; 22(21): 2495-2503. Hughes RE, Chaffin DB, Lavender SA, Andersson GB. Evaluation of muscle force prediction models of the lumbar trunk using surface electromyography. Journal of Orthopaedic Research 1994; 12(5):689-98. Patwardhan AG, Havey RM, Meade KP, Lee B, Dunlap B. A follower load increases the load-carrying capacity of the lumbar spine in compression. Spine, 1999; 24(10): 1003-1009.

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Achondroplasia: 3D - CT Evaluation of the cervical spine I. Tsitouridis, D. Melidis, M. losifidis, A. Morichovitou, F. Goutsaridou, S. Stratilati, G. Giataganas, Ch. Papastergiou.

Radiology Dept, Papageorgiou General Hospital, Thessaloniki, Greece.

The purpose of our study is to present our experience from the evaluation with 3D - CT, 9 patients with spinal achondroplasia. Achondroplasia is the most common form of congenital dwarfism and spinal manifestation is the deformity of the spine due to the achondroplastic configuration of vertebral bodies. The examinations were performed with a spiral CT scanner picker PQ 5000, a Picker Voxel Q visualization workstation. The original axial CT scans were reconstructed in 3D models with MPR, SSD and VR techniques. All the 9 patients revealed small spinal canal, occipitalization of Cl, Cl was hypoplastic in 7 cases and odontoid process was shorter than normal in 5 cases. In one patients there was a C2 - C3 sublutation. 3D - CT reconstractions clearly revealed the whole cervical spine in different angles, which help us to understand clearly the previous reported abnormal findings. In conclusion 3D - CT evaluation of the achondroplastic patients is the method of choice in the detection and characterization of the lesions. Achondroplasia is a rhizomelic short - limbed dwarfism with genetically determined derangements of cartilaginous growth. It is an autosomal dominant disease with a very high mutation rate, so 80% of all cases actually appear as spontaneous mutation in normal families. Males and females are affected equally. Spinal neurologic symptoms, observed in 40 - 50% of patients, result from compression of normal neural structures within an abnormally narrow, ligamentously unstable spinal canal. Clinically, the neurological presentation falls into four major groups (1) progressive insidious onset of increasingly severe paresthesias, sciatic pain and back pain followed by inability to walk and urinary incontinence (2) intermittent claudication with intermittent pain or paresthesia (3) nerve compression signs and (4) acute onset of severe back or leg pain. The ossification centers in cartilage are obnormally small. Insufficient longitudinal growth of enchondral bone reduces the height of the vertebral bodies to one - third normal size. The abnormally large achondromplastic head increases vertical loading on the spine. Thoracolumbar kyphosis is common. The enchondral skull base is small, although the overall head size is increased. The foramen magnum is extremely small and seems to be displaced anteriorly. Basilar impression is present in 37 - 50% of cases. The petrous pyramids may be elevated asymmetrically and the paranasal sinuses are unusually prominent. In our study, we examined 9 patients with achondroplasia. We pointed our interest in cervical spinal anomalies. All the 9 patients had reduced height, (with an average height of 1,2m for males and 1m for females) and had small spinal canal. Occipitalization of Cl revealed in all patients. In 7 cases Cl was hypoplastic and in 5 cases the odontoid process was shorter than normal. Finally in 1 patient there was atlantoaxial subluxation.

All 9 patients were performed with plain radiographs and axial CT scans of the cervical spine. Then we proceed in 3D reconstruction of the original CT scans with MPR, SSD and VR techniques. With the last methods we managed to pick up the previously reported anomalies in detail and to discover same of them not visible in plain scans.

References 1. T. H. Newton, D. G. Potts: Computed Tomography of the spine and spinal Cord, 1983

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Malformations of the craniocervical junction: 3D - CT Evaluation I. Tsitouridis F. Goutsaridou,, A. Morichovitou, G. Giataganas, M. losifidis, D. Melidis, S. Stratilati. Radiology Dept, Papageorgiou General Hospital, Thessaloniki, Greece.

The purpose of our study is to present our experience from the evaluation of the craniocervical junction malformations with 3D - CT. The examinations were performed with a spiral CT scanner picker PQ 5000, a Picker Voxel Q visualization workstation. The original axial CT scans were reconstructed in 3D models with MPR, SSD and VR techniques. In the group of the patients of our study, included 13 patients with malformations of the arches of Cl and C2, 3 with atlantoaxial fusion and irregular segmentation, 5 with fusion of C2 and C3 and the rest with dens malformations. 3D - CT examination clearly picked up the lesions in detail, although some of them also detected with plain radiographs. In conclusion, we believe that 3D - CT is the method of choice in the detection and characterization of the malformations of the craniocervical junction. The malformations of the foramen magnum and upper cervical spine include occipital and suboccipital dysplasia. Occipital dysplasia signifies primary malformation of the occipital bone and includes manifestations of occipital vertebrae, congenital basilar impression, condylar hypoplasia and assimilation of Cl to the occiput. Suboccipital dysplasia signifies primary malformations of Cl and of C2. Those of Cl include aplasia of the arch of Cl, clefts in the arch of Cl, atlantoaxial fusions and irregular segmentation of Cl and C2. Those of C2 ovelap with those of Cl and include atlantoaxial fusions, irregular segmentation of C1 and C2, persistent as terminate and os odontoideum, dens dysplasia, hypoplasia and aplasia, spina bifida of C2 and fusion of C2 with C3. Patients with cervical segmentation anomalies frequently manifest a short or asymmetrical neck or fixed - head position (65%), unilateral high scapula (41%), kyphosis or scoliosis (28%) and miscellaneous other anomalies. Symptoms consist mainly of pain in the occiput and neck, vertigo, unsteady gait, paresis of the limbs and varied cerebellar, medullary and cervical root signs. Symptoms often begin late in life and progress slqwly. In our study, we examined 25 patients with malformations of the craniocervical junction. Of our patients. 13 had malformations of the arches of Cl and C2. There was no complete absence of the anterior or posterior arch of Cl, which is rare. Partial aplasia is more frequent. 3 patients had partial aplasia of the posterior arch of C1: one had aplasia with persisting posterior tubercle, 1 hemiaplasia, 1 partial aplasia of one half an arch. In 1 patient, partial aplasia of the posterior arch of Cl combined with hypertrophy of the dens. The rest 10 patients had clefts within the arches of the atlas, 2 of them anterior and 8 posterior. The posterior clefts were all median. We had no clefts in the arches of axis. 3 of our patients had atlantoaxial fusion and irregular segmentation. In 1 patient we found irregular fusion of the lateral masses of C2 with the arches of Cl. The result was asymmetrical vertebrae with displaced intervertebral joints. The other 2 patients had partial

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fusion of Cl and C2 with in the level of anterior arch of Cl with dens the first and in the level of right hemiarches the second. 5 patients had fusion C2 and C3. 2 of them presented with complete fusion (klippel - Fleil syndrome) and 3 with fusion of the posterior elements only. The last 4 patients had dens malformations. 2 of them with moderate hypoplasia, 1 with hypoplasia with persistent os terminale and 1 with advanced hypoplasia with os odontoideum. All the 25 patients were performed with plain radiographs and then with CT scans of the craniocervical junction. In almost all cases we recognized some of the malformations in plain radiographs and nearly all of then in CT scans. Then we proceed in 3D reconstruction of the original axial CT scans with MPR, SSD and VR techniques. With this method we managed to pick up the lesions in detail and to find out some lesions which were not obvious in the plain CT scans. References 1. T. H. Newton, D. G. Potts: Computed Tomography of the Spine and Spinal Cord, 1983 2. Wackenbeim A: Roentgen Diagnosis of the Craniovertebral Region. New York: Springer - Verlag, 1974 3. Wickbom I, Hopafee W: Soft tissue masses immediately below the foramen magnum. Acta Radiol. 1: 647 - 658, 1963.

Th.B Gnva.M Research into Spinal Deformitie I OS fV<\.v 2/

An experimental model of adult-onset slip progression in isthmic spondylolistesis Avinash Patwardhan, Ph.D.l, Alexander Ghanayem, M.D.I, James Simonds, M.S.2, Scott Hodges, D.O.3, Leonard Voronov, M.D., Ph.D.2, Odysseas Paxinos, M.D J. Robert Havey, B.S.2 'Loyola University Chicago, Maywood, Illinois 2VA Hospital, Mines, Illinois * Center for Sports Medicine and Orthopaedics, Chattanooga, 77V Abstact . Progressive spondylolisthesis may occur in adults with isthmic spondylolysis with an estimated incidence of 20%. This biomechanical study showed that in adult spines with bilateral LS pars fractures, an anterior slip of L5 depends on the extent of the load-bearing deficiency of the disc and the presence of shear force across L5-S1. A combination of disc degeneration and muscle dysfunction may be responsible for converting a stable isthmic spondylolysis into an unstable progressive spondylolisthesis.

1. Introduction Spondylolisthesis is defined as a forward slippage of a vertebral body on the one below. Isthmic spondylolisthesis, caused by stress fracture or a developmental anomaly at the pars interarticularis, is the most common type of lumbar spondylolisthesis at L5-S1. Progressive spondylolisthesis may occur in adults with an estimated incidence of 20%, and is a frequent cause of disabling low-back and leg pain.1 Clinical studies suggest that disc degeneration at the slip level may be a contributing factor to converting a stable spondylolisthesis into unstable progressive slip.1 To date, a laboratory model of adult-onset slip progression in isthmic spondylolisthesis does not exist. Previous biomechanical studies showed that bilateral pars disruption alone failed to produce anterior slip at the affected segment.2-3 The role of the iliolumbar ligament in preventing the progression of L5 slip remains unclear.3 This experimental study quantified the combined effects of the (i) load-bearing deficiency of the intervertebral disc and (ii) loading conditions in causing progressive L5 spondylolisthesis after creation of bilateral pars fractures in adult spines. 2. Methods Five adult lumbar spine specimens (LI-sacrum) were tested intact, after creating bilateral pars fractures at L5, and after partial disc denucleation at L5-S1. Performing a partial disc denucleation simulated the load-bearing deficiency (decreased resistance to load) of a degenerated L5-S1 disc. A small incision was made

A. Putwardhan er al. /An Experimental Model of Adult-Onset Slip Progression

in the posterolateral annulus and a portion of the nucleus was removed. The annular incision was then sutured. The amount of nucleus material removed averaged 62% (±6.3). This procedure decreased the compressive and shear stiffness of the disc, simulating the biomechanical behavior of a moderately degenerated disc.4 The Specimens were tested under the following loads applied across the L5-S1 segment: (i) pure compressive load up to 1200 N, (ii) combined compressive-shear load up to 1200 N, and (iii) flexion-extension moments (± 8 Nm) without a compressive preload. The motion of L5 over sacrum was monitored using (i) an optoelectronic motion analysis system, and (ii) video fluoroscopy giving dynamic radiographic images of the L5-S1 segment. The angular motion and translation (slip) of L5 over sacrum were compared among the different tested cases. 3. Results Under pure flexion-extension moments, the range of motion increased relative to the intact value by 25% (± 7.1) after bilateral L5 pars fractures and by 55% (± 3.8) after partial disc denucleation. However, the flexion-extension moments did not yield any measurable translation at L5-S1. A significant anterior translation of L5 was noted after partial disc denucleation under a combined compressive-shear load across L5-S1. At 1200N, the L5 anterior slip averaged 28% (± 9.1). When the load was removed, the residual anterior slip measured 16% (± 9.8). 4. Discussion Our results showed that a bilateral pars defect can cause increased angular motions, but does not produce anterior slip at the affected segment. This is consistent with previous studies.2'3 In adult spines with bilateral L5 pars fractures, an anterior slip of L5 depends on the extent of the load-bearing deficiency of the disc and the presence of shear force across L5-S1 (Table 1). As the disc degenerates, its capacity to resist the anterior shear forces is considerably diminished. Muscle dysfunction can induce abnormal shear forces at the L5-S1 segment. Thus, a combination of the two factors (disc degeneration and muscle dysfunction) may be responsible for converting a stable isthmic spondylolysis into an unstable progressive spondylolisthesis. Further studies are needed to fully characterize a predictive model of adultonset slip progression to help target preventive modalities such as physical therapy to patients who are at risk to progress. The laboratory model will also allow investigators to objectively compare the biomechanical stability of different fusion constructs under the structural deficiencies and loading conditions that mimic the instability associated with progressive isthmic spondylolisthesis. References 1.

Floman Y. Progression of lumbosacral isthmic spondylolisthesis in adults. Spine 2000;25:342-347.

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A. Putwardhan et til. /An Experimental Model of Adult-Onset Slip Progression

2.

Stokes IAF. Mechanical function of facet joints in the lumbar spine. Clin Biomech 1988;3:101-105. Grobler L, Novotny J, Wilder D, Frymoyer J, Pope M. L4-5 Isthmic spondylolisthesis: A biomechanical analysis comparing stability in L4-5 and L5-S1 isthmic spondylolisthesis. Spine 1994; 19:222-227. Simonds J. Biomechanics of Slip Progression in Spondylolisthesis. M.S. Thesis, Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, June 2001.

3.

4.

Table 1. Slip outcome under differenttest conditions Pars Intact Lysis Lysis

Disc Normal Normal Degenerated

Pure Compression No Slip No Slip No Slip

Combined Compression and Shear No Slip No Slip Grade 2 Spondylolisthesis

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The Significance of Correlation of Radiographic Variables and MOS Shortform Health Survey for Clinical Decision in Symptomatic Low Back Pain Patients Panagiotis Korovessis, Anastassios Dimas, Elias Lambiris Orthopaedic Department, 65-67 Haralabi str., 26224 Patras, General Hospital, Agios Andreas", Patras, GREECE E-mail: [email protected]. Fax: 0030-61-361596 Abstract Objectives. To assess any correlation between SF-36 scores and several lateral roentgenographic variables of the lumbar spine, both in low back pain patients and asymptomatic volunteers. The clinical relevance of the method proposed in this study to make a surgical strategy on the basis of distinct lateral roentgenographic parameters and conversely was assessed by independent radiologists and physicians. Methods. One hundred asymptomatic male volunteers, used as controls and an equal number of age-, height- and weight- comparable consecutive patients with chronic low back pain were examined both roentgenographically and with the SF-36 questionnaire. The roentgenographic variables measured were : lumbar lordosis, sacral inclination, LI to Si vertebral inclination, L4-S| distal lordosis, disc index , and LI to L5 vertebral index. These variables were correlated with the eight SF-36 items both in patients and controls. Both sensitivity and specificity of the method were calculated to assess the impact of subjectivity on the clinical decision. Results. Low back patients showed significantly lower scores than their asymptomatic counterparts, in physical role limitations (PO.01), severity of bodily pain (P<0.01), interference of bodily pain ( P<0.01) and mental health (PO.001). In the controls, general health, physical functioning, social functioning, and role limitations displayed a statistically significant correlation with age, height, weight, lumbar lordosis, sacral inclination, inclination of L|,L3 & L5-vertebra, LI to L5vertebral index and Li-L2, L3-L4, L4-L5 and L$-S\ disc index. In LBP-patients previous general health, physical functioning, role limitations, social functioning, bodily pain were significantly correlated with age, height, Lrand L2-inclination, distal lordosis, Lj-index, and disc index L4-L5, and L5-S,. Although the consensus between either radiologists suggesting a strategy on the basis of roentgenographic data only or between physicians based on only SF-36 data was significant ( P<0.001), there was no consensus in clinical decision between physicians and radiologists. Clinical decision based on matched SF-36 and roentgenographic data made either by radiologists or surgeons showed significant correlations (P<0.001). However, both sensitivity and specificity of our method to make a clinical decision on the basis of radiology were low : 0.48 and 0.36 respectively. Conclusions. SF-36 scores were correlated with distinct lateral roentgenographic variables of the lowermost lumbar spine (L4-SO in low back patients, and of the whole lumbar spine in asymptomatic individuals. Clinical decision should not be taken on the basis of radiological evidence of pathology because clinical decision seems to be more accurate when is taken on the basis of combined SF-36 and roentgenographic data. However, clinical examination is mandatory to SF-36 questionnaire and radiographic analysis.

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P. Komvesxis <•/ til. / Ttic Significance fit Corrclutinn of Rndi(graphic Vuriahles

1. Introduction Traditionally, assessment of LBP severity is based on clinical diagnosis and is best established and agreed in few patients with a clear radiological abnormality. Moreover, in most patients with LBP, it is impossible to reach any definite diagnosis [15], while comparisons of radiographs in patients with LBP and asymptomatic people showed that clinical severity of pain is either related or not to radiological degeneration [1,2,5] . In the past few years, "patient-based" outcome studies included patient's self analysis are becoming increasingly important to clinical researchers [3]. The present study was designed to theoretically assess any correlation between MOS Short Form -36 [4,7,8] items and lateral radiology of the lumbar spine. 2. Material and Methods One hundred asymptomatic male volunteers, and 100 male patients with chronic low back pain (LBP) ages between 20-70 years were included in this prospective study. The two groups, were age-, height and weight comparable. . AH individuals with LBP- symptoms for at least six months. All 200 individuals were examined both clinically and roentgenographically and were given to fill the SF-36 questionnaire. The obtained lateral radiographs [1,4]. were analyzed for (Figure 1)1. lumbar lordosis (T12-S1) [1,4]; 2. sacral inclination [2]; 3. inclination LI to S1:[2,4J. (Figure 1), 4. distal lordosis L4-S1; 5. disc index :(Figure 2); and 6. vertebral index (Figure 2). All above mentioned radiographic variables and the eight SF-36 scales in both groups were statistically analyzed and correlated. Statistical analysis. Simple (SLRA), multiple (MLRA) linear regression analysis and unpaired t-test to compare parameters between the two groups. SF-36 data were blindly assigned to two independent orthopaedic surgeons, and separately the radiological data were blindly assigned by two independent radiologists, to make a clinical decision. Following that the authors attempted to get a consensus between radiologists and physicians. Following that SF-36 data were modified to simulate the case of symptom magnifiers and symptoms reducers, to assess the subjectivity of SF-36 data. To assess the impact of subjectivity of the clinical decision and to calculate the sensitivity and specificity of the clinical recommendations (surgery or not). 3. Results There was a significant correlation in clinical decision that based on SF-36 data (R=0.76, P<0.001); and by independent radiologists that was based on radiographic data (R=0.58, PO.001). Tables 1 to 3. The comparison of the clinical decisions that were based on matched SF-36 and radiology, made by independent surgeons showed significant correlations : Rl = 0.23 (PO.01) and R2 = 0.31 (PO.001). The sensitivity of the method to make a clinical decision on the basis of radiological data was low : 0.48 and the specificity of the method much lower : 0.36.

P. Korovessis et al. / The Significance of Correlation of Radiographic Variables

4. Discussion The nature of "pathological" profile of the lumbar spine and its relationship to subjective assessment of general health status in LBP- patients is still nowadays not exactly defined [5]. The present study demonstrated that the clinical decision, as to operate or not should not be taken on the basis of any kind of radiographic evidence of pathology solely. Clinical decision is reliable when either radiologists or surgeons make their decision based on both SF-36 and radiographic data. An usual question posed by a surgeon is that if he did what is proposed in this study and surgically corrects the lateral spine geometry as recommended on the basis of the results of this study, what is the probability that this procedure would actually resolve his patient's back pain? The rationale for answering these questions was to investigate the clinical relevance (sensitivity and specificity) of the method for making clinical decision proposed in this study. This study showed that we would expect that only 48% of the individuals with abnormal roentgenograms are identified as candidate for operation, while only 36% of the individuals with normal radiographs are identified as normal individuals. Thus, it seems that the validity of the results of this study evaporates with the degree of magnification of the SF-36 data. The results of this study are somewhat consistent with those previously reported on intervertebral disc pathology [10]. Several observational and controversial studies compared pathological findings in radiographic or/and histological studies in individuals with and without LBP and concluded that there was no evidence for the presence or absence of a causal link between these specific radiographic findings and non-specific LBP [6]. The importance of physical and psychosocial workloads as causal factors in LBP has been investigated in different settings [5,10,11,12] In this study, patients with LBP showed significantly lower SF-36 score than their asymptomatic counterparts in role limitations, more severe bodily pain, and mental health level tan their asymptomatic counterparts because of chronic pain. Conclusively, this study showed that clinical decision should not be taken on the basis of radiological evidence of pathology, but on the basis of combined SF-36 and roentgenographic data. However, clinical examination is mandatory to SF-36 questionnaire and radiographic analysis to make an accurate clinical decision and surgical strategy in chronic low back pain patients. . Further studies are necessary to justify the results of this study on a practical and useful basis.

5. Acknowledgment The authors wish to express their appreciation to Georgios Korovessis University of loannina, Greece Computer Science for his assistance in statistical analysis.

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References

10.

12.

Korovessis P, Baikousis A, Stamatakis M: Reciprocal Angulation of vertebral bodies in sagittal plane in an asymptomatic Greek population. Spine 23 ( 1998) 700-705. Tarlov AR. Shattuck lecture - the increasing supply of physicians, the changing structure of the health-service system, and the future practice of medicine. N Engl Med 308 (1983) 1235-1243. Fryback DG, Lawrence WF, Martin PA, Klein R, Klein BE. Predicting Quality of Well-being scores from the SF-36 : Results from the Beaver Dam Health Outcome Study . Med Decis Making 221 (1997) 89-98. Korovessis P, Stamatakis M, Baikousis A. Segmental roentgenographic analysis of vertebral inclination on sagittal plane in asymptomatic versus chronic low back pain patients. J Spin Disordl2(1999)131-7. McDermott W. Absence of indicators of the influence of its physicians on a society's health. Am J Med 70 (1981) 833-842. Ware JE, Snow KK, Kosinski M, Gandek B. SF-36 Health Survey: Manual and Interpretation Guide. Boston, MA : The Health Institute, New England Medical Center, 1993. Brazier J, Jones N, Kind P. Testing the validity of the Euroquel and comparing it with the SF-36 health survey questionnaire. Qual Life Res 2 (1993) 253-65. Stewart LA, Hays DR, Ware EJ. The MOS Short-form General Health Survey. Medical Care 26 (1988)724-735. Baker JG, Fiedler RC, Ottenbacher KJ, Czyrny JJ, Heinemann AW. Predicting follow-up functional outcomes in outpatient rehabilitation. Am J Phys Med Rehabil 77(1998) 202-12. McHorney CA, Ware JE, Lu JF, Sherbourne CD. The MOS 36 item Short Form Health Survey (SF-36) : III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Medical Care 32( 1994) 40-66. Ware JE Jr, Sherbourne CD. The MOS 36 Item Short-Form Health Survey (SF-36) : Conceptual framework and item selection. Med Care 30 (1992) 473-83. Gatchel JR, Mayer T, Dersh J, Robinson R, Polatin P. The association of the SF-36 health status survey with 1- year socioeconomic outcomes in a chronically disabled spinal disorder population. Spine 24 (1999) 2162-2170.

Post

Figure.l: Schematic demonstration of the lateral view of the standing lumbar spine. L.L. = lumbar lordosis, D.L. = distal lordosis, S.I. = sacral inclination, and V.I. = vertebral inclination. (+)

Ant

Figure 2 : Schematic diagram showing the measurements of disc index and vertebral index. Anterior (a) and posterior (b) disc heights are taken as local "minima" at the peripheral endplates. Anterior (c) and posterior (d) vertebral height are measured at the maximum vertebral height. Ant. = anterior. Post = posterior, L4 & L5 = 4th & 5* lumbar vertebra respectively.

P. Korovessis et ai /The Significance of Correlation of Radiographic Variables

Table 1 : Comparative data of Controls versus Low Back Patients

Variables Age (years) Height (cm) Weight (kg) Inclination L1 Inclination L2 Inclination L3 Inclination L4 Inclination L5 Inclination 81 Sacral Inclination Lumbar lordosis

Controls

Low Back Pain Patients

Level of Significance (PM)

49+18 165 + 8 63 + 7 25 + 11 14 + 9 11+9 2.6 + 9 (-9±9) 33 + 4 38 + 15 52 + 13

46+15 166+6 71+13 13 + 8 11+8 6 +7 (-2 ±7) (-15+9) 37+10 38 + 9 49 + 14

NS NS NS

0.013 NS NS NS NS

0.017 NS NS

37+7

33+8.7

0.59 + 0.15

0.7+ 0.25

NS

0.47+ 0.09 0.46 + 0.09

1.6 + 1 0.6.+ 0.45

0.0009 0.0052

Disc index L4-L5

0.37+ 0.09

0.49 + 0.16

0.0044

Disc index L5-S1

0.68 + 0.4

1.43+1

NS

Vertebral Index L1 Vertebral Index L2 Vertebral Index L3 Vertebral Index L4 Vertebral Index L5

0.9 + 0.25 0.99+0.05 0.99+0.06 0.94+0.11 0.9 + 0.07

1.03 + 0.11 1+0.6 1+0.6 0.85+ 0.65

NS NS NS NS

0.06

62+40

38+23

NS

Distal lordosis Disc index L1-L2 Disc index L2-L3 Disc index L3-L4

SF-1*

2+1

NS

SF-2*

60+36

36+18

NS

SF-3* SF-4*

88+18

80+17

NS

82+34

32+44

0.0034

SF-5*

67+38

34+37

0.058

SF-6*

80+28

64+25

NS

SF-7*

73+23

42+17

0.0049

SF-8*

86+21

54+20

0.003

SF-9* SF-10*

80+12 88+25

59+18 70+23

0.0007

SF-11* 70+13 65+17 All values are shown as Mean +SD "Unpaired t-test (Inclination and lordosis are shown in degrees) (* short description of the SF-36 items shown in the Table 1)

NS NS

329

Table 2: Significant Beta Coefficients # between SF-36 and Clinical & Radiological Variables in Low Back Pain Patients General Health

Variables Age Height L4-S1 D.L. Inclin

Physical function (-0.32)**

Role emotional (-0.33)**

Social functioning

Bodily pain (-0.34)***

(-0.26)*

(-0.48)***

L1

0.639***

Vertebral Index L2

0.32**

0.4***

Vertebral Index L5

(-0.30)**

(-0.25)*

Disc L4-L5

(-0.26)*

Disc L5-S1

0.25*

L4-S1 D.L. = distal lordosis, Disc = die index, Index = vertebral index (*) =Beta correlation coefficient, Multiple Linear Regression Analysis, post hoc, Scheffe test. Level of significance : (*), P<0.05; (**), P<0.01 and (***) PO.001

Table 3 : Significant beta-coefficients (#) between SF-36 Items and clinical and radiological variables in asymptomatic individuals General

Physical

Role

Social

Bodily

Mental

health

function

emotional

functioning

pain

health

Age

(-0.32)**

(-0.59)***

Height

0.61**"

Variables

(-0.35)*** (-0.37)***

0.23* (-0.86)***

Lordosis

(-0.9)***

(-0.77)***

Sacral inclination Inclination L1

0.5***

Inclination L3

0.22*

(-0.2)* (-D***

(-0.64)***

(-0.67)***

(-0.8)***

2.41***

0.6***

0.35***

Vertebral Index L2 (-0.48)***

(-1.2)***

(-0.89)***

(-1.1)***

(-1.1)***

(-0.24)*

Vertebral Index L4 0.443***

Vertebral Index L5 Disc Index L1-L2

(-0.34)***

(-0.6)*** 0.221*

Disc index L3-L4 Disc index L5-S1

(-0.49)*** (-0.28)**

Disc index L2-L3 Disc index L4-L5

0.27**

(-0.81)*** 0.704***

0.25** (-0.91)***

(-0.58)*** 0.55***

0.52*

(*) = P<0.05, (**)=P<0.01, (***)=P<0.001 (#): beta correlation coefficient Multiple Linear Regression Analysis, post hoc, scheffe test

1.73***

(-0.72)*** (-0.22)*

Vertebral Index L1

0.731*** (-0.78)***

0.7***

Inclination L5

Vertebral Index L3

(-1-4)*** 0.2*

(-0.47)***

Weight

Vitality

(-0.97)***

Th. H Gnvas I Ed I Research into Spinal Deformities 4 1OS /Vrvv 2 oft 2

Sciatic Scoliosis, its Natural History and the Ability of the Mckenzie Management to Influence it Georgios P. Spanos - PT Dip. MDT, M.I.I. Senior Instructor 35, HeracliouAv., Ill 41, Athens - Hellas 1. The Definition A sciatic scoliosis is a marked Spinal Deformity of Lumbosacral segments'11121 (figure 1). This clinical sign is also called Lumbosacral list, Trunk List'3' or Lateral Shift.'2' AH these names are synonimes to the same clinical situation.

Figure 1 Sciatic Scoliosis

2. The aim

The purpose of this presentation is to understand how the Mckenzie management can influence the natural history of the sciatic scoliosis. 3. The Mckenzie Management This is a well known system of Mechanical Diagnosis and Treatment of Musculoskeletal Disorders. It is based on symptomatic and mechanical response to repeated end range spinal test movements or to prolonged spinal positioning. The system is also based on a detailed history taking of the patient and a very special clinical examination as mentioned above '2'.

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333

4. Material A Sciatic Scoliosis or Trunk List is not a structural scoliosis [2] I3] [41. Also it is not either an infection based scoliosis or an osteoid osteoma t51. Nevertheless, is a marked lumbosacral deformity, very rarely affecting the lower Thoracic Spine, too, as a compensative curve. It is an interesting clinical sign associated with L.B.P. and lumbar disc protrusion or extrusion.'11'2"41'5"61 So far the mechanism of this deformity has not been explained. It is gravity induced in standing or sitting posture but generally, abolished when patient lies down. However, very few acute cases present with a remaining milder deformity even unloaded. The term sciatic scoliosis derives from the often involvement of root tention in a sciatic but not only distribution.[11 [41. 5. "The natural history" The natural history of this deformity has not been adequately addressed nor has been addressed the effect of any theraputic regime or resolution. Some deformities resolve as the symptoms settle down. Some others, don't resolve although the symptoms diminish and the deformity usually becomes permanent between the 8th and 12th weekf1'21 In the majority of these patients the symptoms and the deformity are recurrent.111121 Patient with sciatic scoliosis that attend hospital is more likely to require disc surgery than those without, in a ration 30% versus 10% respectivelly.'71 Attempt have been made to examine the ability of Mckenzie management versus a control group receiving standard back care advise. Trunk list and disability were assessed over a period of 90 days. 6. The Method Patients were randomized into two groups, one receiving non specific back massage and general backcare and the other treating by Mckenzie protocol.181 Both groups attended 2 or 3 times in the first week and less frequently thereafter. Trunk list was defined by the lateral deviation in m.m. of the spinous process of T12 in relation to SI. The measurements were taken blindly over 90 days by independent examiner using the plumbline technique. Various methods are used for the quantitave measurement of the deformity. At this study the blumbline method was used as more simple and reliable.181 Other methods of measurement are by the projected shadow or the 3-space isotrak191, e.t.c. Nevertheless, the Mckenzie system uses the mechanical diagnosis to identify the existence of such deformity. These conditions are classified as derangement syndrome number 4 or 6 in the Mckenzie clasification.121 The Mckenzie system has an extremily high intertester reliability in assessing patients with mechanical low back pain with or without relevant deformities. Many studies strongly support that the interrater agreement for the identification of lateral shift, relevance of lateral compartment, deformity in saggital plane and generally derangement syndrome can be from 0,70 to 1,00 Kappa value. Yet, the prerequisite for these high figures is that the examiners must be well trained in the Mckenzie method.f101 IH1> [121

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7. Results 40 patients with a deformity of more than 5 m.m. with LBP of less than 12 weeks duration entered the study. 18 of them had lower leg pain in a root distribution. 12 had SLR less than 50°. The deformity had resolved in the 64% of the Mckenzie patients by 28 days compared with 50% of the control group. There was a significantly greater resolution (89% compared with 50% of the control group, p=0,04) after 90 days. Other studies resulted at similar figures of resolution but much more quicker, actually within the first week.npl As a matter of fact, data collected from the R. Mckenzie's studies results in a resolution of 93,6% of the population, m these studies 470 patients out of 526 were symptoms free much more quicker, that is in the first week, with full reduction of the deformity. Additionally, the majority of them had great improvement after 24 to 48 hours. In this group the 33% had referred pain in the lower leg and 75% neurological insuficiency. Further, 24 patients out of 526[11 had some delay in their progress. As a matter of fact 18 of them were symptoms free in the first week but some deformity remained, which was corrected the second week. Three patients needed 3 weeks and for the other three remaining it took a month for full correction of the deformity and abolition of the syndromes. Finally, 32 patients out of 526 failed in the management. Twenty seven of them had symptoms of more than 12 weeks duration, 3 of them had symptoms for 8 weeks and 2 had symptoms for 3 and 5 weeks respectively.'11 8. The Mckenzie treatment The Mckenzie treatment follows the principles of the derangement syndrome management. Especially the one for the derangement number 4 or 6. The steps for this treatment are: a. correction of the deformity (figures 2,3,4,5) b. reduction of the derangement c. maintenance of reduction d. restoration of function and e. prophylaxis.1'1121161

Figure 2

Figure 3

Figure 4

Manual convenor! of (he deformitv h\ the Mcken/ie method

Figure 5

G.P. Spanos / Sciatic Scoliosis

335

9. Conclusions - Discussion The Gillan et al study suggests that Mckenzie management may well be an improvement of the natural history of the sciatic scoliosis as 50% of the controlled group had it at 90 days and only 11% of the Mckenzie group.[8] Further, if we consider the figures of the R. Mckenzie's study [11[2] had better results regarding effectiveness, time of treatment and disability, the whole procedure of the Mckenzie method certainly warrants further investigations. In that case, more attention should be paid on the correct application of the principles of Mckenzie method, such as: 1. Treatment should be applied on a daily basis, not twice a week or less. 2. Patient's self correction of deformity and education is of paramount importance. 3. Restoration of lordosis and prophylaxis should be achieved, too. References 1. 2. 3. 4. 5. 6.

7. 8. 9. 10. 11. 12.

R. A. Mckenzie "Manual Correction of Sciatic Scoliosis, NZ Med. Journal 484, 76:194-199, 1972. R.A. Mckenzie "The Lumbar Spine Mechanical Diagnosis and Therapy". ISBN 047300644 Spinal Publications, New Zealand, 1981. RW Porter, CG Miller. "Back Pain and Trunk List". Spine 11:596-600, 1986. J. Kramer. "Intervertebral Disk Diseases, ISBN 3-13-582 402-0. Georg Thieme Verlag, Stuttgart - New York, 1990. PW Porter. "Pathology and Multifactorial Aspects of Symptomatic Disc Protrusion, 3rd Mckenzie Institute International Conference, Torondo, Canada, 1993. R Donelson, C Aprill, R Medcalf, W Grant. "A Prospective Study of Centralization of Lumbar and Referred Pain. A Predictor of Symptomatic Discs and Annular Competence". Spine, 22, 10:1115-1122, 1997. B Khuffash, RW Porter. "Cross Leg Pain and Trunk List" Spine, 14:602-603, 1989. MG Gillan, JC Ross, IP Mcklean, RW Porter. "The Natural History of Trunk List, Its Associated Disability and the Influence of Mckenzie Management". Eur Spine Journal, 7(6) :480-3, 1998. IP Mclean, MG Gillan, JC Ross, RM Aspden, RW Porter. "A Comparison of Methods for Measuring Trunk List". Spine, 21:1667-1670, 1996. S Kilpikoski et al. "Interexaminer Reliability of Low Back Pain Assessment Using the Mckenzie Method". Spine, 27:E 207-E 214,2002. H Rajmjou, JF Kramer, R Yamada. "Intertester reliability of the Mckeknzie Evaluation in Assessing Patients with Mechanical Low Back Pain" J Orthop & Sports Phys Ther, Jul;30(7):368-383,2000. MS Donahue, Riddle DL, Salivan MS. "Intertester Reliability of a Modified Version of the Mckenzie's Lateral Shift Assessments obtained on patients with L.B.P." Phys Ther 1996;76:706-716

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Pathomechanic basics of conservative treatment of progressive idiopathic scoliosis according to Dobosiewicz method based upon radiologic evaluation Krystyna Dobosiewicz, Jacek Durmala, Krzysztof Czernicki, Hanna Jendrzejek Department of Rehabilitation, Medical University of Silesia, Katowice, Poland 40-635 Katowice, ul. Ziolowa 35/37, POLAND e-mail rehabilitacjasam @poczta. onet.pl Abstract Conservative treatment of idiopathic scoliosis, especially kinesitherapy, is not widely appreciated due to its suspected low effectiveness in relation to a surgical treatment. After long-year assessment of patomechanics of scoliosis in Department of Rehabilitation of Medical University of Silesia a conservative method of treatment, asymmetric trunk mobilization in strictly symmetric positions, was developed. This method enables to detain progression of scoliosis, or even decrease lateral curvature of a spine and angle of rotation assuming adequate cooperation of patient and its family.

1. Introduction Idiopathic scoliosis (IS) is a three-dimensional deformation of a vertebral column and entire trunk. After many years of extensive researches the cause of idiopathic scoliosis still remains unknown. It is possible that idiopathic scoliosis develops and progress on a basis of multifactor disorder, perhaps different for curve initiation and curve progression. From possible pathologic factors nervous system dysfunctions affecting postural equilibrium and proprioceptive control seem to be especially important. [1,2, 6, 3] Progression of IS could be determined by vertebrae remodeling under eccentric loading created by axially acted gravitational forces in presence of muscular imbalance in the trunk. [2] The vertebral column under scoliotic conditions is an unstable system with tendency to further curve development. [12] Lateral bending of a vertebral column, visible in X-ray examination, is only a two-dimensional presentation of a complex deformity, consisting of pathological axial rotation, torsion and other deformations of vertebrae. [7, 8, 10, 11, 14] In IS physiologic curvatures of vertebral column are disturbed. Total length of an anterior column of a spine, consisting of vertebral bodies and intervertebral discs, becomes greater than length of a posterior column - vertebral arches and processes. [11, 15] It is apparent that physiological thoracic kyphosis in region of a scoliotic curve diminishes. Each vertebra of a structural curve of scoliosis is orientated in hyperextension in relation to adjacent vertebrae, [7, 11] resulting

337

K. Dobosiewicz et al. / P athome chanic Basics of Conservative Treatment

Fig. I .

Symmetric t

Symmetric exercise positions (1-5) and intermediate position (I). Derotation forces during asymmetric mobilisation of a trunk.

in decreased kyphosis or even true lordosis in an affected region. Axial rotation in hyperextended region produces picture of lateral curvature, described as rotation lordosis. [10, 13] The two factors, overextension and rotation, reflex lateral curvature development, eventually aggravated by positive feedback of eccentric load in condition of muscular instability .

2. Kinesitherapeuthic method of treatment according to Dobosiewicz: trunk mobilization in strictly symmetric positions

asymmetric

Main assumption of kinesitherapeuthic method developed by Dobosiewicz is creation of thoracic kyphosis and derotation of vertebrae with simultaneous dilation of intercostal and paravertebral spaces on the concave side of scoliosis. Basic foundations of method of asymmetric trunk mobilisation in strictly symmetric positions depend on type of scoliosis, value of thoracic kyphosis and asymmetry of pelvis position. [6, 4, 5] Following conditions should be met to attain demanded effect: - Initial exercise positions should be maximally kyphotic and strictly symmetric to allow adequate extend of asymmetric movement of a trunk (Fig. 1). Most initial positions exclude action of erector spinae and psoas major muscles and axial gravity load on vertebral column. Stabilisation is provided by superficial muscles of chest and back, mostly pectoralis major and minor, anterior serrate, trapezius, rhomboidei and latissimus dorsi.

K. Dolwsiewic- el nl. / Pathomechanic Ruxica of Conservative Treatment

- Asymmetric movement of a trunk is conducted accommodating intercostal muscles and a diaphragm. Asymmetric contraction of intercostal muscles in the concave area in symmetric position causes physiological 'buckle handle' movement of ribs. This kind of movement elevation and rotation in costo-vertebral joints - effects in dilation of intercostal and paravertebral spaces and derotation of vertebrae (Fig. 2). Eventually lateral curvature of vertebral column also decreases. - Muscles of anterior abdominal wall serve for movement control and correction of pelvic rotation and inclination. Oblique muscles mainly correct axial pelvic rotation and additionally stabilise initial position. Rectus abdominis muscle rotating pelvis around a transverse axis (decreasing angle of inclination) causes additional elongation of a thoracic and lumbar segment. Elongation primarily concerns with posterior columns of a spine, producing further correction of a scoliosis. 3. Material 208 children (21 boys and 187 girls aged 6-19, mean 13.8 M and 14.3 F) suffering from idiopathic scoliosis has been treated since November 1999 till September 2001 in Department of Rehabilitation of Medical University of Silesia. 114 of them presented single scoliosis and 94 double-major scoliosis. In single scoliosis mean Cobb angle was 11 - 55° (mean 33.2_ ± 17.1_), angle of axial rotation 3 - 20 ° (mean 9.4 ° ± 6.1_). In double major scoliosis Cobb angle in thoracic region was 12 - 66 ° (mean 34,2_ ± 15.1_), angle of axial rotation 3 - 30 ° (mean 12.6 ° ± 8.9_). In lumbar region of double major scoliosis Cobb angle was 20 - 59 ° (mean 35.3_ ± 12.4J and angle of axial rotation 4 - 30 ° (mean 17.8 ° ± 10.2J.

K. Dobosiewicz el al. / Pathomechanic Basics of Conservative Treatment

4.

339

Method of treatment

X-ray evaluation of scoliosis was carried out in standardised technical conditions at least twice in periods of at least 6 months. Cobb angle and angle of axial rotation of an apical vertebra according to Pedriolle technique were measured always by the same physician.

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K. Dohosicwic: et ni / Ptithinneclutnic Hastes of Conservative Treatment

5. Results Results of treatment obtained on the basis of X-ray evaluation of progression of a scoliosis (Fig. 3) are shown in Table 1. Method of asymmetric trunk mobilization in strictly symmetric positions is especially valuable in treatment of single structural curves of IS. Results in double major scoliosis are less promising, but still worth considering. Proposed method was applied mostly in children in age of puberty and related adolescent growth 'spurt'. Natural history of scoliosis progression shows usually dramatic scoliotic curve worsening related to this period of life. [9] This opportunity furthermore advocates proposed method of treatment. 6. Conclusions Table 1. Results of Dobosiewicz method of conservative treatment of idiopathic scoliosis. single scoliosis Cobb angle rotation angle

regression progression regression progression

33.6% 33.6% 21.6% 19.8%

Double major scoliosis thoracic region 22.8% 28.3% 16.3% 25.0%

lumbar region 26.1% 28.3% 16.3% 30.4%

1. Method of asymmetric trunk mobilization in strictly symmetric positions in most cases results at least in detention of a scoliosis progression. Proposed method should be then considered in scoliosis treatment as a single method of treatment or as an element of rehabilitation before planned surgery. 2. In conservative method of treatment biomechanical function of a vertebral column remains preserved and benefits in further quality of life of patients. References 1. 2. 3. 4.

5.

Abbott Byrd J.: Current theories on the etiology of idiopathic scoliosis. Ciin Orthop. 229,1988,114-119. Burwell R. G.: The aetiology and pathogenesis of adolescent idiopathic scoliosis (AIS). Eur. Spin. Resonances 1994, 3-6. Dobosiewicz K., Czernicki K., Dyner-Jama I.: Mono- and polysynaptic reflexes in aetiology of idiopathic scoliosis. European Spine Journal, 1999,8 (Suppl. 1), 34. Dobosiewicz K., Durmala J., Dyner-Jama I. et al.: Evaluation of the conservative treatment (asymmetric mobilisation of the trunk in strictly symmetric positions) of idiopathic progressive scoliosis by radiological and exercise efficiency testing. European Spine Journal 2001,10 (Suppl. 1), 58. Dobosiewicz K., Durmala J., Kotwicki T. et al.: Wp_yw asymetrycznej mobilizacji tu_owia na zachowanie si_ k_ta Cobba i rotacji w przypadkach bocznych idiopatycznych skrzywie_ kr_gos_upa u dzieci i m_odzie_y. Post_py Rehabilitacji, 2001, XV(3), 21-22.

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6. 7. 8. 9.

10. 11. 12. 13. 14. 15.

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Dobosiewicz K.: Boczne idiopatyczne skrzywienia kr_gos_upa. Slaska Akademia Medyczna, Katowice 1997. Dubousset J, Herring J. A., Shufflebarger H.: The crankshaft phenomenon. J. Pediatr. Orthop., 1989, 5, 541-550. Dubousset J.: Three-dimensional analysis of the scoliotic deformity. In: Weinstein S. L. (ed.): The pediatric spine, Raven Press, New York, 1994,479-496. Duval-Beaupere G.: Pathogenic relationship between scoliosis and growth. In: Ph. Zorab (ed.): Scoliosis and growth. Proceedings of a 3rd symposium held at the Institute of Diseases of the Chest, Brompton Hospital, London, 13 Nov 1970. Churchill Livingstone, 1970, pp. 57-63. Pedriolle R.: La scoliose. Son etude tridimensionelle. Maloine S. A. (ed.), Paris, 1979. Roaf R.: The basic anatomy of scoliosis. J. Bone Joint Surg., 1966,48-B, 786-792. Smith T. J., Fernie G. R.: Functional biomechanics of the spine. Spine 16 (10), 1991,1197-1203. Sommerville E. W.: Rotation lordosis: the development of the single curve. J. Bone Joint Surg., 1952, 34-B, 421-427. Tylman D.: Patomechanika bocznych skrzywie_ kr_gos_upa. Severus, Warszawa, 1995. Winter R. B., Lovell W. W., Moe J. H.: Excessive thoracic lordosis and loss of pulmonary function in patients with idiopathic scoliosis. J. Bone Joint Surg., 1975, 57-A. 972-977.

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Conservative management in patients with scoliosis - does it reduce the incidence of surgery? Hans-Rudolf Weiss, Grita Weiss, Hans Jiirgen Schaar Asklepios Katharina-Schroth-Klinik, Korczakstr. 2, D-55566 Bad Sobernheim Abstract The effectiveness of conservative scoliosis treatment, including bracing, is widely denied. Like any therapeutic intervention, conservative scoliosis treatment including patient education, techniques of brace moulding, and time-consuming follow-ups is reasonable only if the benefits outweigh the strain placed upon the patient by the treatment. The most important benefit of early intervention in scoliosis is prevention of the need for spinal fusion surgery. Retrospective analysis of the incidence of surgery for patients with scoliosis, by comparison with incidence in an untreated control group. Since 1992 the bracing technique according to Cheneau has been applied in parallel with the scoliosis inpatient intensive rehabilitation programme (SIR). For this study we chose from our data base the scoliosis patients who had conservative treatment at our center between 1993 and 1996. All patients, like those of the control group, were at least 15 years of age at the time they were evaluated for the last time. The incidence of surgery of our group was compared with that reported by a center in Ireland. Of 343 female scoliosis patients with a curve angle of 33.4^€ (SD=18.9), 41 (11.95%) had surgery. The incidence of surgery of our collective was significantly lower than the incidence of surgery of the control group which reported an incidence of 28,1%. The AIS matched group of patients (n = 179) had an incidence of surgery of slightly more than 7%. When compared with a matched control group of untreated patients, incidence of surgery was significantly reduced by SIR combined with bracing. So conservative management is indicated in patients with scoliosis.

1. Introduction On the one hand the literature confirms the effectiveness of certain orthoses in the treatment of scoliosis [1, 2], and yet on the other hand their effectiveness is generally denied and the treatment is widely rejected [3, 4]. Although conservative methods of treatment with physiotherapy and braces are generally accepted in central Europe as special branches [5, 6], conservative treatment in the USA is largely discounted. In addition to the language barrier, which is so prejudicial to the English-speaking countries in that it reduces the availability there of up-to-date information about conservative methods of treatment of scoliosis, a number of mistaken and unhelpful ideas even exist in the practice of this treatment which, far from being beneficial to patients, may actually put strain on them [7]. In Germany conservative treatment is regarded as effective if a curvature shows no further progression (even when further growth is expected) or if there is a clear tendency towards a decreasing curvature. Hanks et al. [7] nevertheless speak of successful brace treatments in the USA, providing the increase of the curvature is no greater than IQJE. Based on our own review of the literature we were able to prove that there does indeed

H.-R. Weiss et al. / Conservative Management in Patients with Scoliosis

343

exist a direct positive correlation between the primary effect of an orthosis and the end result [8]. In his study of the treatment of idiopathic scoliosis with the aid of the ChSneau brace, Landauer [2] also concludes that compliance on one hand and the primary effect of the brace on the other, are the main parameters of successful brace treatment. In the USA however braces are not very often "custom-made". They are able to achieve a corrective effect of 50% in relation to the initial curvature, but only on smaller curves, and thus may indeed exercise an essential influence on the final prognosis [9]. This shows that the question of the effectiveness or not of conservative treatment in general and of scolioses orthoses in particular is very complex and cannot be answered on a onedimensional basis. By contrast the treatment of scoliosis with the Cheneau brace is currently most practised here in Germany [10] .The clinical histories of individuals enjoying excellent corrective effects and favourable outcomes are encouraging the use of this method here. We must emphasise nevertheless that however well-adjusted an orthosis may be, there do indeed exist curvatures whose progression cannot be halted. And so we ask the following questions: are our efforts reasonable and worthwhile - involving as they do the time-consuming education of patients, moulding techniques and follow-ups, and the strain put on patients by all the conservative methods? Or should we follow the American way of scoliosis treatment? - that is to say, "Wait until the scoliosis has to be corrected surgically!" In a recent study Goldberg and her collaborators [4] analysed the incidence of surgery in patients with adolescent idiopathic scoliosis at several centres in which a comparison between the incidence of surgery in braced patients and the incidence of surgery in non-braced patients was made. The authors concluded in their study that as far as the number of surgical interventions was concerned, from a statistical point of view, patients who used a Milwaukee brace in the years between 1950 and 1970 did not differ from untreated patients in the 90's. Although the methodology of this study showed some weaknesses [6] it has enabled us to use the collective of Goldberg et al. [4] as a control group for a retrospective study of our own. When offered unbiased information, many patients, even those with curvatures of over 40M, nevertheless opt for conservative treatment. And so in order to be able to explain to patients whether surgery is a reasonable procedure or not, we thought it would be useful to make a study of the effectiveness (or not) of conservative scoliosis management including outpatient physiotherapy, inpatient intensive scoliosis rehabilitation and brace treatment.

2. Material and method In order to answer the question as to whether conservative methods (outpatient physiotherapy, inpatient intensive rehabilitation (SIR) and brace treatment - in this case mainly the Cheneau brace - are effective, we have compared the incidence of surgery in patients presenting various kinds of aetiology treated conservatively at the our centre with the incidence of surgery reported by Goldberg et al. [4] in patients without conservative management. In the study by Goldberg and her collaborators [4] the criteria for inclusion were: 1. Diagnosis of adolescent idiopathic scoliosis 2. Minimum age of 15 years at last check-up (not younger than 10 years at first check-up) 3. Documentation for Cobb angle without brace at first check-up (at least 10°). Curve pattern distribution was given for the whole collective. In girls, menarchial status and the incidence of surgery were also known. In order to be able to compare the patients at our centre who had had one or more

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inpatient intensive courses of rehabilitation (with or without brace) with the collective of Goldberg and her collaborators [4] we followed their study design. All patients (girls only in our study, aged between 10 and 13) diagnosed with scoliosis of every kind of aetiology and who had attended our centre between 1993 and 1996, were included in this study. As not all patients in this group had had repeated treatment at our centre or had had only outpatient appointments elsewhere, the study was conducted by means of a questionnaire. 689 patients were sent questionnaires by post.The number of responses was low - only 214 questionnaires were returned. We could not therefore present any convincing results with this group, and so all patients who failed to answer our questionnaire received a phone call and were subsequently sent the questionnaire for a second time. In this way we were able to reach 343 patients out of the described group. All others had moved away from their original addresses. The average angle of curvature according to Cobb before the first inpatient intensive course of rehabilitation was 33.4 ° (SD=18.9), which was comparable to the angle of curvature evaluated by Goldberg et al. (33 °) [4]. The distribution of the pattern of curvature was as follows: 1. Thoracic scolioses: 35% 2. Double major scolioses: 37.2% 3. Lumbar scolioses: 10.2% 4. Thoracolumbar scolioses: 17.2% 244 of the patients studied (71 %) wore braces. 235 of these also gave details of how long they wore their braces for. 58 patients (25%) wore the brace for up to 8 hours daily, 47 patients (20%) for up to 16 hours, 54 patients (23%) 16-21 hours, and 76 patients (32%) more than 21 hours daily. In surgically treated scoliosis patients (n=41) the angle of curvature according to Cobb was 50 ° (SD=25.4).

3. Results Patients treated with a programme of inpatient intensive scoliosis rehabilitation (SIR) showed an incidence of surgery of 11.95%; the patients in the Goldberg collective however showed an incidence of 28.1%. The differences are statistically highly significant. Out of the first 214 patients who sent back completed questionnaires, 11% had been treated surgically, whereas out of the 343 patients who were finally included in the study, 41 had had surgical treatment. There was no statistical difference between the incidence rate reported in the questionnaires returned initially and the incidence of surgery in the whole collective. A one-sided statistical test for the comparison of two independent proportions was used [11]. Using this method of testing highly significant differences with a test value of 3.995 at p< 0.0001 (a=0.05) were shown by reference to Goldberg's collective (no brace treatment, incidence of surgery 28.1%, n=153). Comparing this value with the Milwaukee-braced control group of Lonstein and Winter [12] (incidence of surgery 22.4%, n=1020) a highly significant difference was also evident (test value 4.7553, p< 0.0001 (a=0.05)). The differences by reference to the control group without brace treatment as studied by Noonan and co-workers [13] (surgery incidence 31%, n=88) reveal a similarly high significance. There was a probability of error of p=0.0001 with a test value of 3.6329).When comparing the diagnosis-matched patient groups (Adolescent idiopathic scoliosis Goldberg n =153, incidence of surgery 28.1% versus Weiss n = 179, incidence of surgery 7.3%) we found a test value of 5.05 with a probability of error of p<0.0001 (_=0.005).In comparing the late-onset-scolioses in the Goldberg collective (There where only adolocents in their study) the collective with the

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early-onset-scolioses in our own collective (infantile idiopathic scoliosis and juvenile idiopathic scoliosis thus with a much worse prognosis) we found no significant differences (with a probability of error of p=0.087). Had there been a higher number of cases however, the limit of significance would also have been passed. Patients with adolescent idiopathic scoliosis present an incidence of surgery of slightly over 7%. Patients with kyphoscoliosis show an incidence of surgery of 2.6%. Thus patients with adolescent idiopathic scoliosis present the less favourable form of scoliosis compared with that of kyphoscoliosis. 4. Discussion In their introduction Goldberg and her co-workers [4] cite two references [9], Fernandez-Feliberti et al. [14] in which a good compliance of the patients favoured the outcome of bracing However they omit the important point that in the study by Emans et al. [9] the actual extent of the corrective effect is also described as an essential criterion in successful bracing. This is supported by the study by Mellerowicz and co-workers [ 15] and the research done by Landauer [2]. The importance of the corrective effect is also confirmed by a review of the literature [8]. The study by Nachemson and Peterson [1] also proves the effectiveness of bracing. Certainly, Thulbourne and Gillespie [16] are right in saying that even if the progression can be reduced by bracing, cosmetic appearance and the rib hump may not always be influenced positively, nor may a successful course of treatment, as revealed by X-ray, always be appreciated as such by the patient. Nevertheless one must point out that neither self-image nor other psychological factors can be affected by surgical treatment either! [17]. Bettany and co-authors conclude that 6 months after surgery, levels of pain and emotional problems connected with scoliosis remain unaltered by most of the current surgical techniques; and the cosmetic results directly obtained by surgery are not necessarily stable later on either! One year after surgery a good cosmetic initial result may deteriorate and a reduced rib hump may become clearly evident again [18]. Goldberg and her co-workers [4] affirm that not only has the Cobb angle to be considered in cases of surgical treatment, but that cosmetic appearance and the chances of obtaining a visible improvement have also to be taken into account. However the study by Goldberg and her co-workers [4], although suitable as a control group for our conservatively treated group of patients, has to be examined more closely for its value as a positive statement. According to the manual [19] used by Goldberg and her co-workers [4], the validity of statistical test methods should be approached more cautiously when confirming the HO-hypothesis (non-significant differences). Distinction must be made between the statistical statement itself and its medical relevance. Assessment of this statistical data suggests that the non-significant differences reported can in no way be regarded as proof of the ineffectiveness of the method of treatment. The statement succeeds only in proving that in that particular study and in the conditions described, no significant differences could be found. The statistical data of the statement are therefore clearly distinct from any medical relevance they may have to an evaluation of the results of the study in general. Even when following this manual [19], a different interpretation from that of Goldberg and her co-workers[4] be placed upon the outcome by highlighting the fact that medically relevant differences were certainly found between the untreated control group, with an incidence of surgery of more than 28%, and the brace group treated with the Milwaukee brace with an incidence of surgery of only 22.4%. This is reason enough to believe that treatment involving bracing with a Milwaukee orthosis does indeed have some effect. However, to conclude from a

346

H.-R. Weiss ct dl / (. i/n\(i'\'(iti\t Mdinmcnicnt in Pmicnis with Scolinsis

study which used only one brace (outmoded by today's standards!) that bracing with any kind of bracing system should be rejected, simply does not stand up against the scientific evidence. Is the reason for the less favourable results obtained in patients conservatively treated in Ireland and the United States perhaps due to the fact that there is not sufficient control of the quality of treatment in the methods applied? In any case it is obvious that conservative methods of treatment should never be ruled out from scoliosis treatment because these can and do offer a viable alternative to those patients who cannot or do not wish to opt for surgical treatment. 5. Conclusions 1. Conservative methods of treatment with outpatient physiotherapy, inpatient intensive rehabilitation and high-correction braces have clearly proved their effectiveness in reducing the incidence of surgery in female patients with idiopathic scoliosis. 2. Cosmetic appearance seems to have played a minor role in female patients' decisions to opt for or against surgical treatment.

References 1 2

4 5 h 7 s 11

!() 1 i 12 13 14 15

AL. Nachemson, LE. Peterson, Effectiveness of Treatment with a Brace in Girls Who Have Adolescent Idiopathic Scoliosis. J Bone Joint Surg I Am] 77 (1995) 815-822. F. Landauer F, 1st die Therapie mil dem Che*neau-Korsett wirksam? In: A. Imhoff A (Hrsg.) Fortbildung Orthopadie - Die ASG-Kurse der DGOT, Bd. 2: Wirbelsaule. Steinkopff, Darmstadt, 1999, pp. 31-38. CJ. Goldberg, FE. Dowling, JE Hall et a/.., A Statistical Comparison Between Natural History of Idiopathic Scoliosis and Brace Treatment in Skeletally Immature Adolescent Girls. Spine 18 (1993) 902-908. CJ. Goldberg, DP. Moore, EE. Fogarty, FE. Dowling FE, Adolescent Idiopathic Scoliosis: The Effect of Brace Treatment in the Incidence of Surgery. Spine 26 (2001) 42-47. R. Bauer, F. Kerschbaumer, S. Rehart, Skoliose. In: CJ Wirth (Hrsg.) Praxis der Orthopadie, Bd 1: •Conservative Orthopadie. Thieme, Stuttgart, 2001, pp. 498-502. HR. Weiss, Letter to the editor. Spine 18 (2001) 2058-2059. G. Hanks, B. Ziminer, J. Nogi, TLSO Treatment of Idiopathic Scoliosis - An Analysis of the Wilmington Jacket. Spine 13 (1988) 626-629. HR. Weiss, Standard der Orthesenversorgung in der Skoliosebehandlung. Med. Orth. Tech. 115 (1995)323-330. JB. Emans, A.Kaelin, P.Bancel et al.. The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients. Spine 11 (1986) 792-801. HR. Weiss, M. Rigo, J.ChSneau, Praxis der Chfineau-Korsettversorgung in der Skoliosetherapie. Thieme, Stuttgart, 2000. M. Bland, An introduction to medical statistics. Oxford: Oxford University Press 1989. JE. Lonstein, RB. Winter, The Milwaukee brace for the treatment of adolescent idiopathic scoliosis.: Review of 1020 patients. J Bone Joint Surg [Am] 76 (1994) 1207-21. KJ. Noonan, AD. Lori, WC. Jacobson, SL. Weinstein, Long-term psychological characteristics of patients treated for idiopathic scoliosis. Journal ofPediatric Orthopaedics 17 (1997) 712-717 R. Fernandez-Feliberti, J. Flynn , N. Ramirez et al., Effectivevess of TLSO bracing in the conservative treatment of idiopathic scoliosis. J Paediatr Orthopead 15 (1995) 176-81. H. Mellerowicz, T. Bockel, G. Neff, R. Frey, Mittel- und Langzeitergebnisse der Behandlung von lumbalen Skoliosen mit dem Boston-Brace. Paper read at the 42. Annual meeting of the Vereinigung Suddeutscher Orthop&kn e.V., April 28th. to May thelst., Baden-Baden, 1994.

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16 17

18

19

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T. Thulbourne, R. Gillespie, The rib hump in idiopathic scoliosis. Measurement, analysis and response to treatment. J Bone Joint Surg [Br] 58 (1976) 64-71. J. Bettany et al., Topographical, Kinesioiogical and Psychological Factors in the Surgical Management of Adolescent Idiopathic Scoliosis. In: M. D'Amico, A. Merolli, GC. Santambrogio (eds.), The threedimensional Analysis of Spinal Deformities. IOS Press, Amsterdam, 1995, pp. 321326. J. Bettany et al., Are back shape changes following scoliosis surgery stable? A prospective three year . follow-up of five different surgical procedures. Paper read at the European Spinal Deformities Society Meeting,, Birmingham, England, May 31st -3rd June 1994. LE. Daly, GJ. Bourke, Interpretation and uses of medical Statistics. Fifth edition 2000, Blackwell Science, London, pp. 73-74.

^4S

Th.B.GrivamEd.) Research into Spinal Deformities 4 IOS Press. 2002

Influence of method of asymmetric trunk mobilization on shaping of a physiological thoracic kyphosis in children and youth suffering from progressive idiopathic scoliosis Krystyna Dobosiewicz, Jacek Durmala, Hanna Jendrzejek, Krzysztof Czernicki Department of Rehabilitation, Medical University of Silesia, Katowice, Poland 40-635 Katowice, ul. Ziolowa 35/37, POLAND e-mail: rehabilitacjasam @poczta. onet.pl Abstract. Idiopathic scoliosis (IS), which is substantially a threedimensional deformation of a spine, causes not only lateral curvature and axial rotation of vertebral column, but also lordotisation of vertebrae in structural curve extension. In an effect physiological thoracic kyphosis diminishes or even disappears. Method of asymmetric trunk mobilisation in strictly symmetric positions according to Dobosiewicz not only deteriorates progression of IS or even reduces lateral curvature, but also significantly rebuilds physiological thoracic kyphosis in cases of IS accompanied by straight back.

1. Introduction Despite long year researches etiology of IS is not yet resolved. Significant problem related to morphology of IS, apart from lateral bending and axial rotation, is deviation of shape of a spine in sagittal axis, affecting physiological curvatures of vertebral column [3, 5, 6, 8, 9,10, 11, 12]. Length of anterior column of a spine, constituted by vertebral shafts and intervertebral discs, dominates over length of posterior column built from vertebral arches and processes [10]. This condition during scoliosis progression and growth of a child effects in shallowing or even disappearing of physiological thoracic kyphosis in scoliotic region. It is well known that vertebrae of structural lateral curve are positioned in hyperextension - lordotisation [5, 6], which in thoracic region leads to reduction of kyphosis or to true lordosis. Such kind of vertebrae relations in thoracic region causes its destabilisation, which in association with eccentric gravitational load of a spine due to muscular imbalance [2] possibly produces 'rotational lordosis' [5,6,11] and further development of symptomatic scoliosis. It has been proven [12] that strengthening of the erector spinae muscle aggravates once initiated deformation and deteriorates scoliotic process. Hyperextension and axial rotation associated with

K. Dobosie u /< r a nl. /Influence of Method of Asvmmctric Trunk Mohili'.ation

Fig. 1. reformation of thoracic kyphosis in IS.

eccentric load lead to spinal imbalance on a principle of positive feedback or create conditions for deterioration of musculo-ligamentous instability of a vertebral column. The common point of described mechanisms is that decrease of physiological kyphosis - or straight back - can lead to either initiation or fast progression of once induced scoliosis. 2. Aim of the study The aim of the study was clinical analysis of an influence of kinesitherapy method according to Dobosiewicz on thoracic kyphosis in children and youths suffering from progressive idiopathic scoliosis. 3. Material and method Study was carried out on the material of 392 scoliotic patients aged 6-19 years (353 girls aged 6-19, mean 14.3 ± 2.63 and 39 boys aged 6-16, mean 13.8 ± 3.67). Among assessed children 219 were single scoliosis cases and 173 double major scolioses. In single scoliosis mean Cobb angle [1] was 33.4 ° ± 17.7 °, in double major scoliosis mean Cobb angle in thoracic region was 34 ° ± 15.05 ° and in lumbar region 30 ° ± 12.1 °. 60% of children with single scoliosis (kyphosis range -6 ° to 27 °, mean 16.7 ° ± 7.7 °), and 64.3% children with double major scoliosis (kyphosis range -3 ° to 27 °, mean 18.1 ° ± 7.05 °) initially presented straight back.

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K. Dobosiewicz et al. /Influence of Method of Axvmmetric Trunk Mobilization

Fig. 2 and 3. Clinical measurement of thoracic kyphosis.

Patients were treated using Dobosiewicz method of asymmetric trunk mobilisation in strictly symmetric positions [3, 4]. Active exercises were supported by passive stretching of a spine in frontal and sagittal plane in Gasser-Smith net. Mean period of treatment was 21 days ± 3. Kyphosis was clinically evaluated using Rippstein plurimeter and SFTR method [7] (Fig. 2 and 3). Measurements were carried out in standardised conditions by always the same physician on the beginning and on the end of a treatment period. 4. Results In single scoliosis increase of a kyphosis was diagnosed in 54% of straight back cases, mean improvement was 6.8 ° ± 2.9 °. Decrease of thoracic kyphosis occurred in 2.5%, mean deterioration was 4.3 9 ± 1.23 °. In double major scoliosis increase of a kyphosis occurred in 61.2% of straight back cases, mean improvement was 5.1 ° ± 2.9 °. In this group decrease of a thoracic kyphosis was not stated (Tab. 1.). Despite of short time of observation of treated patients obtained results seem to be satisfying. Employed method of kinesitherapy of idiopathic scoliosis according to Dobosiewicz assumes maximum possible, extended during exercises kyphotisation of vertebral column. These rules are focused on efficient stretching of muscles, ligaments and Table 1. Changes of thoracic kyphosis after Dobosiewicz method of conservative treatment of IS.

single scoliosis double major scoliosis

increase of kyphosis % of study group [mean value and SD] 54.0% [6.8° ±2.9°] 61. 2% [5.1° ±2.9°]

no kyphosis change % of study group

43.5 % 38.8 %

decrease of kyphosis % of study group [mean value and SD] 2.5%[4.3U±1.23U] 0%

articular capsules constituting or adjacent to posterior column of a spine. Passive extension in Gasser-Smith net additionally enforces effects of essential treatment. Eventually contractile structures of back are being elongated effecting in rebuilt of physiological thoracic kyphosis.

K. Dobosiewicz et al. /Influence of Method of Asymmetric Trunk Mobilization

35 I

In view of reviewed scoliosis development principles restoration of thoracic kyphosis reduces or even arrests further progression of lateral scoliotic curvature [3,4]. 5. Conclusions 1. Dobosiewicz method of conservative treatment of a scoliosis in a short time period significantly increases thoracic kyphosis in children with progressive idiopathic scoliosis associated with straight back. 2. Presented method increases thoracic kyphosis in progressive idiopathic scoliosis associated with straight back and thus slows down progression of a lateral curvature. References 1. 2. 3. 4.

5. 6. 7. 8. 9. 10. 11. 12.

Borejko M., Dziak A.: Badanie radiologiczne w ortopedii. PZWL, Warszawa 1988, pp. 35-53. Burwell R. G. The aetiology and pathogenesis of idiopathic scoliosis (AIS). Eur. Spin. Resonances 1994, 3-6. Dobosiewicz K.: Boczne idiopatyczne skrzywienia kregos_upa. Slaska Akademia Medyczna, Katowice 1997. Dobosiewicz K., Durmala J., Kotwicki T., Jendrzejek H., Jedrzejewska A., Czernicki K., Bialon E.: Wplyw asymetrycznej mobilizacji tulowia na zachowanie sie kata Cobba i rotacji w przypadkach bocznych idiopatycznych skrzywien kregoslupa u dzieci i mlodziezy, Post_py Rehabilitacji, 2001, XV(3), 21-22. Dubousset J., Herring J. A., Shufflebarger H.: The crankshaft phenomenon, J. Pediatr. Orthop., 1989; 5: 541-550. Dubousset J.: Three-dimensional analysis of the scoliotic deformity. In: The Pediatric Spine, Weinstein S. L. (ed.), Raven Press, New York 1994, pp. 479-496. Gerhardt J. J., Rippstein J. R.: Gelenk und Bewegung. Verlag Hans Huber, Bern 1992. Kotwicki T.: Trojplaszczyznowa analiza skolioz idiopatycznych leczonych operacyjnie. Doktorate, Medical University of Poznan 1999, pp. 1-6. Perdriolle R.: La scoliose. Son etude tridimensionnelle. Maloine S. A. Editeur, Paris 1979. Roaf R.: The basic anatomy of scoliosis, J. Bone Joint Surg., 1966,48-B, 786-792. Sommerville E. W.: Rotation lordosis: the development of the single curve. J. Bone Joint Surg., 1952, 34-B, 421-427. Tylman D.: Patomechanika bocznych idiopatycznych skrzywien kregoslupa. Wydawnictwo Severus, Warszawa 1995.

ThB GrivaslEd.i Research into Spinal Deformities 4 IOS Press. 2
Curvature progression in patients treated with scoliosis in-patient rehabilitation - A sex and age matched controlled study Hans-Rudolf Weiss, Grita Weiss Asklepios Katharina-Schroth-Klinik, Korczakstr. 2, D-55566 Bad Sobernheim, Abstract. The aim of this study is to test the hypothesis that physiotherapy-based intervention can reduce incidence of progression in children with IS because progression of spinal curvature in patients with idiopathic scoliosis (IS) is of paramount concern in treatment strategies. Follow-up of the outcome of two prospective studies using the outcome parameter, incidence of progression (>5°), in treated and untreated patient groups matched by age, sex, and degree of curvature at diagnosis. A six-week scoliosis in-patient rehabilitation (SIR) program offering patient-specific physiotherapy including intensive therapist-assisted exercise in diagnosis-matched groups. A followup home therapy regime is designed for each patient. Incidence of progression in groups of untreated patients ranged from 1.5-fold (71.2% vs 46.7%) to 2.9-fold (55.8% vs 19.2%) higher than in groups of patients treated with SIR, even when SIR-treated groups included patients with more severe curvatures. Statistically, the differences were highly significant. Postural imbalance is a component of spinal curvature and can be a causative mechanism. However, efforts to test the hypothesis that physical therapies addressing postural imbalance can be used effectively in the treatment of IS have been limited. The results of this study indicate mat a supervised program of exercise-based therapies can reduce incidence of progression in children with IS.

1. Introduction In Europe, a conservative treatment approach is pursued actively from the time of diagnosis based on the rationale that postural imbalance is an integral component of scoliosis irrespective of its cause [1]; and therefore postural balancing treatment is a logical approach to ameliorate clinical aspects of spinal deformity [2, 3, 4, 5, 6]. In Germany, this approach includes outpatient physiotherapy beginning at 15°. Scoliosis intensive rehabilitation (SIR) is recommended for curvatures of 20 ° to 30 °, with or without bracing, depending on prognosis [7, 8, 9, 10, 11, 12]. For adult IS, outpatient physiotherapy is offered for curvatures of 30° to 40° with moderate pain. Physiotherapists in different regions are trained, so that patients have the option of outpatient treatment close to their residence. For adult patients with curves over 40° in association with cardiorespiratory functional impairment and pain, SIR is recommended. In-patient treatment offers structure for a daily six-hour intensive rehabilitation treatment. Following the criteria of Bloch [13] results from cohort studies and case follow-up studies are consistent with the conclusion that physiotherapy is effective in treating signs and symptoms of scoliosis [7, 8, 9, 10, 11, 12].

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353

The purpose of the current study was to compare incidence of curvature progression in two populations of patients, with and without an intensive in-patient physiotherapy regime.

2. Materials and Methods Study design Follow-up (of groups matched by sex, age, and degree of curvature) of the outcome of two different prospective studies using the outcome parameter 'incidence of progression1 in patients with idiopathic scoliosis, with and without SIR treatment. Subjects The goal of the current study was to analyse statistically the incidence of progression in the SIR-treated group with the incidence of progression in a control group. The data for this study are from a prospective follow-up of patients, who had SIR, without bracing (Study A) and from a prospective follow-up [14] of untreated patients from the same geographical region of Germany (Study B). Patients with prior treatment by lateral electrical surface stimulation [15] or surgery were excluded. Study A In a prospective follow-up study of 181 patients with idiopathic scoliosis we evaluated the incidence of progression in patients with SIR treatment. Of the 181 patients, 156 were female, 25 were male. The average Cobb angle was 27° before the study, the average Risser stage was 1.4 with an average follow-up period of 33 months. Curvature patterns included thoracic (35%), thoracic lumbar (7%), lumbar (28%), and double major (27%). Study B The prospective natural history study by Hopf et al. [14] which was done within the same geographical area of Germany (Rhineland-Palatinate), served as the control group (Table 1). In this study, 135 patients (111 girls and 24 boys) with an average age of 10 years, and a follow-up period of 52.4 months were included [14]. In 59% of the patients, Risser sign was 0; 13.2% had Risser 1; 12.3% had Risser 2; 6.6% had Risser 3; and 8.5% had Risser 4. The curvature was less than ten degrees in 18.5% of the population. Building of comparable groups out of Study A and B. As there was no essential progression in the group of the 15-year-old patients, only younger patients were included. Matching groups were formed from Study A and Study B based on age and sex, as described by Lonstein and Carlson [16] and Hopf et al. [14] and included Group I (up to 12 years of age); and Group II (12-14 years of age). Male patients were excluded. Group I: From Study A, thirty SIR-treated female patients met criteria for inclusion in Group I (Table 1). Their average age was 9.9666 ±0.85 years and mean curvature angle was 21 ±10.7 degrees, with a range from 6 to 52 degrees. The average follow-up was 35 months. The average Risser sign was 0.3 degrees. Group la was a subset of Group I (Study A), in which the patients' curvature range (6-27 degrees) closely matched that of the control Group I. The average age for Group la was 10.04 years, Risser 0.24, average Cobb angle 17.2 degrees. Group I from the untreated control Study B included 64 patients whose curvatures ranged from 5-30 degrees. Group II. Study A, Group II included fifty nine female patients with an average age of 13.4 ±0.71 years and an average curvature angle of 29.5 ±14.3 degrees, with a range from 8 to 68 degrees. The average follow-up was 34.3 months (Table 1). The average Risser sign was 2.3 degrees. Group Ha was a subset of Group n consisting of thirty three patients with an average age of 13.4 ±0.71 years and curvatures ranging from range 8-29 degrees;

354

average Risser sign 2.1, average curvature 19.42 degrees. Group lib was a subset of Group II including those patients with more severe curvatures, ranging from 30 to 68 degrees; Risser 2.8, average age 13.5 years. The mean follow-up period was 36 months. Study B, Group II included 43 patients with curvatures ranging from 5 to 30 degrees. Scoliosis in-patient rehabilitation SIR employs an individualized exercise program combining corrective behavioural patterns with physiotherapeutic methods, following principles described by LehnertSchroth [6]. The three-dimensional scoliosis treatment is based on sensomotor and kinesthetic principles and its goals are (1) to facilitate correction of the asymmetric posture, and (2) to teach the patient to maintain the corrected posture in daily activities. Data acquisition and analysis The test parameter used to measure progression was Cobb angle; all measurements were carried out blind, without reference to previous patient records, by a reader who is independent of this study [17, 18]. An increase of >5 degrees in angle of the most severe curvature was used to define 'progression.1 A onesided statistical test to compare two independent proportions was used to test the hypothesis that the proportion of patients with progression differed between the two study groups [19]. 3. Results Group I (<12 years of age): Within the untreated control Group I, curvatures of 71.2% of patients whose initial Cobb angles ranged from 5 to 30 degrees progressed by >5 degrees. Even though more severe curvatures (range 6-52 degrees) were included in the SIR Group I, the incidence of progression in the SIR test group was only 46.66%, and was statistically distinct at the 0.011 level of probability (Table 1). Within the SIR test subgroup la, whose range of curvatures was closely matched with that of the control group, only 40.0% of the cases progressed. The difference was statistically significant at the 0.0029 level of probability.

Table 1. Progression in matching subset of treated and control groups Source (a) Weiss I*

n** Ila***

Total

Aee

Curve

FoUowuo

Procression

30 59 26

10±P.85 13±0.71 13.6+0.5

21±10.7 29.5±14.3 42.3+10.9

35±23 34±37 36+34.1

14/30 (46.7%) 18/59(30.5%) 5/29 (19.2%)

64 43

<12 12-14

5-30 5-30

52.4 52.4

45/64 (71.2%) 24/43 (55.8%)

(b) Hopf

I*

n**

'Inclusion criteria: Female only; Age <12; Cobb angle <30) ""Inclusion criteria: Female only; Age 12-14; Cobb angle (<30) """Inclusion criteria: Female only; Age 12-14, Cobb angle >30 degrees

H.-R. Weiss and G. Weiss / Curvature Progression in Patients Treated with Scoliosis

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Group II (ages 12-14): Within the untreated control Group II, curvatures of 55.8% of patients whose initial Cobb angles ranged from 5 to 30 degrees progressed by >5 degrees (Table 1). Within the SIR test Group II, in contrast, curvatures of only eighteen of fifty nine patients (30.5%) progressed by >5 degrees, even though more severe curvatures (range 868 degrees) were included. These differences were statistically distinct at the p<0.0045 level of probability. In Group Ila, nearly-matched for curvature severity (8-30 degrees for SIR, 5-30 degrees for controls), incidence of progression for SIR treatment was 39.4% compared with 55.8% in the controls, but the values were not statistically distinct (Table 1). In Group lib, which included the most severe initial curvatures (30-68 degrees), incidence of progression was only 19.2%. This value was distinct from that of control Group II at the 0.0004 level of probability (Table 1). 4. Discussion The possibility that physical methods can be used to treat scoliosis was controversial by the time of Hippocrates, and remains so to this day [20, 21, 22]. Since no other vertebrate species suffers from a comparable spinal deformity, the use of experimental animals to translate principles into clinical approaches that reliably allow patients to avoid surgery have not been successful [23]. Testing treatment effectiveness in a controlled manner in humans is complicated by ethical issues. Because no human patient can be denied treatment that might be effective in the interest of proving that it is effective, establishing control samples to compare outcome is difficult for any disease or deformity. The fact that any given population of patients with IS includes cases with divergent and unknown etiologies, makes evaluation of treatment protocols especially problematical. The role of a specific treatment in improvement in an individual child is always questionable because curvatures can stabilize or improve spontaneously prior to skeletal maturity [24]. If the hypothesis that physiotherapy is an effective treatment for IS is correct, a prediction is that the incidence of progression will be higher in a population of untreated patients than in a comparable population of patients who received SIR. The results revealed that incidence of progression in untreated patients was higher than in patients treated with SIR, even when the prognosis of the SIR-treated group was substantially less benign than that of the control group, exhibited an incidence of progression that was lower than any other group. The results suggest that a supervised program of exercise-based therapy can significantly reduce the incidence of curvature progression in IS, and are consistent with a previous report of reduced progression in children treated with posture-balancing exercise [25]. In addition, improved curvature flexibility was achieved in response to a ten-day exercise program [26], and a recent case report documents dramatically improved chest wall mobility and function in moderately severe IS in response to physical methods in a previously untreated, middle aged adult [27]. Taken together, the results are consistent with the hypothesis that the signs and symptoms of IS can be positively influenced by physical therapies, and highlight the need for research to develop proactive methods to intervene in spinal deformity at early stages of development. References 1. 2.

PH. Harrington, Is scoliosis reversible? Clin Orthop Rel Res. 116 (1976) 103-11. GP. Dmitrieva, RD. Nazarova, AA. Peresetsky et al., Efficiency of the conservative treatment in idiopathic scoliosis. Mathematical models of the effect of the brace treatment in patients with

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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.

H.-R. Weiss and (i Weiss / Curvature Progression in Patients Treated \\'itli Scnli<>sis

adolescent idiopathic scoliosis. In: IAF Stokes (ed.), Technology and Informatics. Research into Spinal Deformities 2. IOS Press, Burlington, Vermont, 1999, pp. 325-328. P. Klisic, Z. Nikolic, Attitudes scoliotiques et scolioses idiopathiques: prevention a I'ecole. Personal communication. Journees Internationales sur la prevention des scolioses a I* age scolaire. Rome 1982. G. Motion, JC. Rodot, Scolioses structurales mineures et kinesitherapie. Etude statistique comparative et resultats. Kinesither Scient. 244 (1986) 47-56. M, Rigo, G. Quera-Salva, N. Puigdevall, Effect of the exclusive employment of physiotherapy in patients with idiopathic scoliosis. Retrospective study. In: Proceedings of the llth International Congress of the World Confederation For Physical Therapy. London, 28 July - 2 August, pp. 13191321,1991. Ch. Lehnert-Schroth, Dreidimensionale Skoliosebehandlung. 6. Auflage. Urban & Schwarzer, Stuttgart, 2000. HR. Weiss, K. Lohschmidt, N. El Obeidi, Ch. Verres, Preliminary results and worst-case analysis of in-patient scoliosis rehabilitation. Pediatric Rehabiliation 1 (1997) 35-40. HR. Weiss, Skolioserehabilitation. Qualita'tssicherung und Patientenmanagement. Thieme, Stuttgart, 2000. HR. Weiss, M .Rigo, Befundgerechte Physiotherapie bei Skoliose. Pflaum, MUnchen, 2001. HR. Weiss, Influence of an in-patient exercise program on scoliotic curve. Italian Journal of OrthQpaedics and Traumatology 3 (1992) 395-406. HR. Weiss, The effect of an exercise program on vital capacity and rib mobility in patients with idiopathic scoliosis. Spine 1 (1991) 89-93. HR. Weiss, Scoliosis-related pain in adults - treatment influences. European Journal of Physical Medicine and Rehabilitation 3 (1993) 91-94. R. Bloch, Methodology in clinical back pain trials. Spine 12 (1987) 430-432. Ch. Hopf, E. Sandt, J. Heine, Die Progredienz unbehandelter idiopathischer Skoliosen im Rdntgenbild. Fortschr. Rdntgenstr. 151,3 Thieme, Stuttgart, 1989, pp. 311-316. DE. Rowe et al., A meta-analysis of the efficiency of non-operative treatments for idiopathic scoliosis. J Bone Joint Surg. [Am} 79 (1997) 664-667. JE. Lonstein, JM Carlson, The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg. [Am] 66 (1984) 1061. JR. Cobb, Outlines for the study of scoliosis measurements from spinal roenlgenograms. Physical Therapy 59 (1948) 764-765. HR Weiss, N. El Obeidi, Relationship Between Vertebral Rotation and Cobb-Angle as Measured on Standard X-Rays. In: M. D'Amico et al. (eds). Technology and Informatics. Threedimensional Analysis of Spinal Deformities. IOS Press, Amsterdam, Oxford, Washington DC, 1995, pp. 155-159. M. Bland, An introduction to medical statistics. Oxford: Oxford University Press 1989. F. Adams, The Genuine Works of Hippocrates. Williams and Wilkins, Baltimore, 1939. RA. Dickson, SL. Weinstein, Bracing (and screening)-yes or no? J Bone Jt Surg 81-B (1999) 193198. KY. Moen, AL Nachemson, Treatment of scoliosis; an historical perspective. Spine 24 (1999) 25702475. E. Bleck, Adolescent idiopathic scoliosis. Dev Med ChildNeur. 33 (1991) 167-176. WP. Bunnell, An objective criterion for scoliosis screening. J. Bone Joint Surg (Ami 66A (1984) 1381. MH. Merita, Active auto-correction for early adolescent idiopathic scoliosis. J Bone Jt Surg. 68 (1986) 682. RA. Dickson, KD. Leatherman, Cotrel traction, exercises, casting in the treatment of idiopathic scoliosis: A pilot study and prospective randomized comparisonled clinical trial. Acta Orthop Scand, 49(1978)46-48. MC Hawes, WJ. Brooks, Improved chest expansion in idiopathic scoliosis after intensive, multiple modality, nonsurgical treatment in an adult. Chest 120: (2001) 672-674.

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Exercise efficiency of girls with idiopathic scoliosis based on the ventilatory anaerobic threshold Jacek Durmala, Krystyna Dobosiewicz, Hanna Jendrzejek, Wieslaw Pius Department of Rehabilitation, Medical University ofSilesiaa, Katowice, Poland 40-635 Katowice, Ul. Ziolowa 45/47 POLAND e-mail: durmalaiacek_poczta. onet.pl Department of Physiology, Academy of Physical Education, Katowice, Poland

Abstract. The aim of the study was to estimate the exercise efficiency in the group of girls with idiopathic scoliosis based on the ventilatory anaerobic threshold (VAT). Material and method. The investigation comprised 58 girls with idiopathic scoliosis, aged 10--6 years; 32 girls (55.20/0) with double major scolioSiS and 26 girls (44.8%) with single scoliosis. The girls were conservatively treated using Dobosiewicz method. The control group consisted of 3 1 healthy girls aged 10-1 6 years. The exercise test was performed using cycle ergometer. During the exercise the gas exchange parameters were recorded (minute expiratory ventilation, minute oxygen consumption, carbon dioxide production). On the basis of recorded parameters VAT has been computed, using V-slope method. Results. The following VAT values were obtained in the group with scoliosis: 20.7+3.05 ml 02/min/kg b.m.; in control group: 21.9+3.50 ml 02/minlkg b.m. The differences between girls with idiopathic scoliosis and control group were not statistically significant. Conclusions. I. The exercise efficiency of girls with idiopathic scoliosis conservatively treated using Dobosiewicz method is normal. 2. Such high level of the exercise efficiency of the studied group probably was due to intensive 3-D respiratory exercises of these girls.

1.

Introduction

In practice there are researched useful efficiency rates which on base of laboratory tests results, possible easy, without using of the relatively hard or long exercise tests, would give the better forsighting of the range of homeostasis disturbances and rapidity of increase of physical fatigue during varied workloads [1]. The best known rate of this kind is the maximal minute oxygen consumption [2,3,4,5]. During progressive physical effort minute oxygen consumption increases proportionally to workload. The reaching of real maximal minute oxygen consumption in time of progressive effort is indicated by minute oxygen consumption plateau [5,6]. This result is rarely registered in children. The progressive exercise test is most commonly used in children until physical exhaustion and the highest registered minute oxygen consumption is treated as maximal minute oxygen consumption or so-called symptomatic limited maximal minute oxygen consumption [6,7,8]. Some authors regard

35S

J. Purmala a at. IE\ercisc Efficiency of Guis with Idiopathic Scoliosis

value of minute oxygen consumption as maximal (in adults) without reaching plateau, when respiratory quotient (RQ) >1,0 and ratio minute expiratory ventilation/rn mute oxygen consumption (VE/VO2) >35 [5,6]. The level of workload where first time appears unproportionally high elevation of VE related to V02 is described as ventilatory anaerobic threshold (VAT). Many physiologists and clinicians count the anaerobic threshold as better exercise efficiency marker than maximal minute oxygen consumption [5,9,10]. Ventilatory anaerobic threshold was stated as authentic noninvasive exercise efficiency rate also in children [11,12]. The aim of the study' was to estimate the exercise efficiency in the group of girls with idiopathic scoliosis based on the ventilatory anaerobic threshold. 2.

Material

The investigation enveloped 58 girls with idiopathic scolios is, aged 10-16 years (mean age 13.1 ±1.90 years); 32 girls (55.2%) with double major scoliosis (thoracic segment -Cobb angle 12-76°, mean 35.4 °± 16.78; X-ray axial rotation angle 3-30 °, mean 13.6 °±9.05; lumbar segment - Cobb angle 20-59 °, mean 34.9° ±12.97; X-ray axial rotation angle 4-32°, mean 18.9°±10.34); thoracic kyphosis 5-39°, mean 22.4 ° ±8.02; lumbar lordosis 15-42°, mean 27.2 ° ±8.06) and 26 girls (44.8%) with single scoliosis (Cobb angle 11-55°, mean 29.3° ±16.96; X-ray axial rotation angle 3-20 °, mean 9.1 ° ±6.04; thoracic kyphosis 138 °, mean 21.4 ° +11 62 lumbar lordosis 14-42 °, mean 30.1° ±8.16). The girls were conservatively treated using Dobosiewicz method - treatment period ranged from 2 months to 2 years (mean 12, 3 months 16,18). The control group consisted of 31 healthy girls, aged 10-16 years (mean age 12.4+1.87 years). The examined girls participated in school only in scheduled physical education lessons and have not been enrolled in other sporting activity. 3.

Method

The exercise cycle ergometer test was performed in constant conditions (air temperature 18-22 ®C, relative humidity 50-60%, morning hours). The incremental exercise test has been applied. The workload was increased stepwise by 15 Waif every minute. The test had been continued until reflisal of the patient or exceeding the pulse limit. During the exercise the gas exchange parameters were recorded (minute expiratory ventilation, minute oxygen consumption, carbon dioxide production) by Jaeger device model Oxycon Alfa using direct breath-by-breath method (Fig. 1). On the basis of recorded parameters VAT has been individually computed for each girl, using V-slope method and was re-counted according to the body mass [5]. All girls of the studied group presented normal values in spirometry. 4.

Results and discussion

The following VAT values were obtained in the group -with scoliosis: 20.7+3.05 ml 02/min/kg b.m.; in the control group: 21.9±3.50 ml 02/min/kg b.m. The differences between girls suffering from idiopathic scoliosis and control group were not statistically significant. All girls from the study and control group have been classified among normal range of

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359

predicted values of VAT for age, height and weight [13].

Figure 1. Ergospirotnetry test.

In other study of 19 girls (treated with Dobosiewicz method) with right thoracic scoliosis, aged 12-16, the exercise efficiency estimated on the ground of the VAT value was normal [14]. In another publication the statistically significant increase of VAT value in the group intensively treated during short 15-18 days period using Dobosiewicz method was described [15]. The normal exercise efficiency of children treated by Dobosiewicz method has been confirmed also by studies using maximal oxygen consumption analysis [16]. 5. Conclusions 1. The exercise efficiency of girls with idiopathic scoliosis conservatively treated using Dobosiewicz method is normal. 2. Such high level of the exercise efficiency of the studied group was probably due to intensive 3-D respiratory exercises of these girls. References 1 2 3 4 5 6 7 8

J. Durmala, Wydolnose wysilkowa dzieci pO chirurgicznej korekeji prostych wad serca. Doctorate, Medical University of Silesia, Katowice, 1998. V. Bune, A simple method for estimating aerobic fitness, Ergonomics 37(1994) 159-165. S. Kozlowski, K. Nazar.Wprowadzenie do fizjoiogii klinic~nei. PZWL, Warszawa, 1984. R. Kuhica, Podstawy fizjoiogii pracy i -dolnos'ci fizycznej. AWF, Krakow, 1995. K. Wasseiman, J. F. Hansen, D. Y. Sue, B.J. Whipp, R. Casaburi. Pnnciples of exercise testing and interpretation. Williams & Wilkins, Philadelphia, 1994. P. A. Nixon, D. M. Orenstein, Exercise testing in children, Pediatric Puhnonology' 5 (1988)107-122. T. W. Rowland, Does peak V 02 reflect V C^max in children?: evidence from supramaximal testing, Med. Sci. Sports Exerc. 25 (1993) 689-693. T. W. Rowland, L.N. Cunnigharn, Oxygen uptake plateau during maximal treatmill exercise in children, Chest 101 (1992) 485-489.

360

9 10 11 12

13 14

15

16

J. Durmala ct til. /Exercise Efflciencv of Girls with Idiopathic Scoluisis

H. Haliezka-Ambroziak, R. Jusiak, A. Martyn, B. Opaszowski, J. Szarska, M. Tyszkiewicz, B. Wit, Wskazowki do ewiezen z fizjologii dia studentow wychowania fizycznego. AWE, Warszawa, 1993. W. Pius, R. Zarzeczny, M. Langfort, Pr6g przemiaii beztlenowych. AWE, Katowice, 1996. T. Reybrouck, M. Weymans, H. Stijns, J. Knops, L. Van der Hauwaert, Ventilatory anaerobic threshold in healthy children, EuropeS AppL Physiol. 54 (1985) 278-284. T. Reybrouck, M. Weymans, H. Stijns, (}.Van der Hauwaert, Ventilatory anaerobic threshold for evaluating exercise performance in children with congenital left-to-right intracardiac shunt, Ped. Cardioi. 7(1986)19-24. W. Tomalak, K. Pisiewicz, B. Baran, U. Jedrys-Klucjasz, Predicted values for ergospirometry test in children and adolescents aged 8-19 years3 Pediatria Poiska 75 (2000) 953-957. J. Durmala, K. Dobosiewicz3 W. Pius, H. Jendrzejekj I. Dyner-Jama, M. Plak, K. Czernicki, M. Szota, W. Krotki, A. Jedrzejewska, Wydolnosc wysilkowa nastolatek z bocznym3 piersiowym skrzywieniem kregoslupa3 Ada Pneumonologica et A/lergologica Pediatrica 4 (2001) 70. K. Dobosiewiez, J. Durmala, J. Dyner-Jama, H. Jendrzejek, J. Kohut, M. Flak, W. Pilis, Evaluation of the conservative treatment (asymmetric mobilisation of the trunk in strictly symmetric positions) of idiopathic progressive scoliosis by radiological and exercise efficiency testing, European Spine Journal 10(2001)58. J. Durmala, K. Dobosiewiez, W. Pilis3 B. Manowska, H. Jendrzejek, J. Kohutj I. Dyner-Jama, K. Czernicki, M. Flak, Ocena wydolnosci fizycznej dziewczat z bocznym idiopatycznym skrzywieniem kregoslupa na podstawie oznaczania maksymalnego minutowego pobierania tlenu metod4 bezpos'redmPosteoy Rehabilitacji 15 (2001) 22-23.

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Side Shift Exercise for Idiopathic Scoliosis after Skeletal Maturity Toni Mamyama', Tomoaki Kitagawal, Katsushi Takeshita^, Kozo Nakainura^ 1. DepL ofOrthopaedic Surgery, Teikyo University School ofMedicine 2-JJ-Jkaga, Itabashi-ku, Tokyo]?3-8605 JAPAN 2. Dept. ofOrthopaedic Surgery, Tokyo University School ofMedicine

Abstract. A total of 69 patients with idiopathic SCO1-OS-S who were treated only by side shift exercise after their skeletal maturity were reviewed. The average age at the beginning of the side shift was 16.3 years and the average follow-up period was 4.2 years. Size of the curve was 31.5°+11.2 at the beginning of the side shift and 3O.3-J12.3 at the final follow-up. The side shift exercise can be a useful treatment option for the management of idiopathic scoliosis after skeletal maturity.

1. Introduction Side shift exercise was originally described by Mehta [1]. The exercise consists of the lateral trunk shift to the concavity of the scoliotic curve. Lateral tilt at the inferior end vertebra is reduced or reversed, and the curve is corrected in the side shift position (Figure 1). Since 1986, we adopted the side shift exercise for the treatment of idiopathic scoliosis. Patients are instructed to shift their trunk to the concavity of the curve repetitively while they are standing and to maintain the side shift position while they are sitting. Magnitude of the shift is decided according to the direction of the patient's spinal list. If C7 plumb line lies to the convexity of the curve at the level of the sacrum, large shift is indicated, and if C7 plumb line lies to the concavity of the curve at the level of the sacrum, small shift is indicated. For a double major curve, the larger curve is the subject of the treatment. Our indications of the side shift exercise are: 1. Curves too small for brace treatment (e.g., Cobb angle <25°) 2. Combined with part-time brace treatment (e.g., Cobb angle > 25~, Risser grade 0 to IV) 3. Curves after skeletal maturity (e.g., Risser grade IV or V, postmenarche > 2 years) The purpose of this study is to evaluate the outcome of the side shift exercise for patients with idiopathic scoliosis after skeletal maturity.

Figure 1. A patient with idiopathic scoliosis, standing in neutral (a) and in the side shift position (b). X-ray of the same patient (c. d) showed that the curve is corrected in the side shift position.

2. Materials and Methods The subjects of the study were patients with idiopathic scoliosis, who started side shift exercise after skeletal maturity, who received no other treatment during the follow-up period, and whose follow-up period was more than one year. There were 69 patients (62 females, 7 males) with 32 single thoracic curves, 12 single thoracolumbar curves, and 25 double major curves. For a double major curve, the larger curve was included in the analysis. The average age at the beginning of the side shift was 16.3 years (range: 11-27) and the average follow-up period was 4.2 years (range: 1.2- 11 .5). Cobb angle at the beginning of the side shift and that at the final follow-up were compared. 3. Results Size of the curve was 3 1.5°±11.2 ° (range: 13-74 °) at the beginning of the side shift and 30.30±12.3° (range: 7-73 °) at the final follow-up. Ten curves increased 5 ° or more, while 15 curves decreased 5 ° or more; four of them decreased 10 ° or more (Figure 2 and 3). Changes of residual 44 curves were within 5 °. Table I and 2 show the results by curve pattern and by curve size. In the range of 3O ° 5O ° of which natural history was reported in a few long-term studies, there were 33 curves (17 thoracic, 3 thoracolumbar, and 13 double major curves) averaged 36.6 ° at the beginning of the side shift and 36.1 ° at the final followup. Table 1 . Results by curve pattern Curve pattern Number Follow-up Cobb angle Cobb angle of curves (years) at the beginning at the final follow-up 4.4 Thoracic 32 32.7±9.7 31.3±11.5 Thoracolumbar

12

3.8

24.5±10.1

22.9±11.5

Doublemajor

25

4.0

33.0±12.6

32.6±12.8

T. Mamyama et al. /Side Shift Exercise for Idiopathic Scoliosis

363

Table 2. Results by curve size Curve size (Cobb angle)

Number of curves

Follow-up (years)

Cobb angle at the beginning

Cobb angle at the final follow-up

10-19

7

4.2

15.6±2.1

13.1±3.6

20-29

24

4.2

23.8±2.7

22.8±6.O

30-39

22

3.6

33.6±2.9

32.6±4.9

40-49

11

5.8

42.5±2.1

42.9±6.5

50-59

4

2.6

52.0±2.4

48.O±5.6

60-

1

3.8

74

73

4. Discussion Most of the long-term follow-up studies reported that untreated idiopathic scoliosis progressed even after skeletal maturity. For thoracic and thoracolumbar curves of 30°-50°, Weinstein SL and Ponseti IV [2] reported O.25~ progression per year with 40.5 years followup, and Ascani E et al. [3] reported 0.36 ° progression per year with 33.5 years follow-up; However, in this study, 33 curves of 3O ° -5O ° showed 0.1 ° per year improvement during 4.3 years. Follow-up period of the present study may be too short to compare these results with those of the long-term follow-up studies. Some treatment, however, should be attempted for the patients with idiopathic scoliosis even after their skeletal maturity.

Figure 2. Case 1 . At the beginning of the side shift (14 years 9 months), Rt. T7-L2 curve was 38-. C7 plumb line was located 0.5 cm left to the center of the sacrum (a). At the final follow-up (16 years 2 months), curve decreased to 250. C7 plumb line was 1.5 cm left to the center of the sacrum (b).

Figure 3. Case 2. At the beginning of the side shift (17 years 5 months), Rt. T4-11 curve was 55Q C7 plumb line was 1~5 cm right to the center of the sacrum (a). At the final follow-up (19 years 8 months), curve decreased to 42-. C7 plumb line was 0.5 cm right to the Center of the sacrum (b).

}f>4

7 Muni\iini(i et al. /Side Shift Exercise for Idiopathic Scoliosis

5. Conclusion The side shift exercise can be a useful treatment option for the management of idiopathic scoliosis after skeletal maturity. References 1. 2. 3.

M.H.Mehta, Active Correction by Side-shift: An Alternative Treatment for Early Idiopathic Scoliosis. In: Scoliosis Prevention. Praeger, New York, 1985. pp.126-140. S.L. Weinstein and I.V. Ponseti, Curve Progression in Idiopathic Scoliosis, J Bone Joint Surg 65-A (1983) 447-455. E. Ascani et al., Natural History of Untreated Idiopathic Scoliosis after Skeletal Maturity, SPINE 11 (1986)784-789.

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Reversal of the Signs and Symptoms of Moderately Severe Idiopathic Scoliosis in Response to PhysicalMethods Martha C. Hawes, Ph.D.1 & William J. Brooks, D.O.2 1 Department of Plant Pathology, University of Arizona, Tucson AZ 8572 J U£A. ^Restorative Care Foundation, Kansas City, MO 64152 USA.

Abstract. This report describes improved signs and symptoms of previously untreated symptomatic spinal deformity in an adult female diagnosed with moderately severe thoracic scoliosis at the age of .7 years. Current treatment initiated at the age of forty included massage therapy, manual traction, ischemic pressure, and comprehensive manipulative medicine (CMM). A left-right chest circumference inequity was reduced by >10 cm, in correlation with improved appearance of the ribcage deformity and a 40% reduction in magnitude of Cobb angle, which had been stable for 30 years. The changes occurred gradually over an eight-year period, with the most rapid improvement occurring during two periods when CMM was employed.

1.

Introduction

Thoracic scoliosis is associated with restrictive lung disease occurring secondary to ribcage deformity and corresponding loss of chest wall compliance [1]. Chest wall compliance is reduced in inverse correlation with curvature severity down to a Cobb angle often degrees, and vital capacity is reduced in direct correlation with loss of chest wall compliance [1,2]. Exercise capacity also is inversely correlated with magnitude of Cobb angle, even in patients whose resting VC is within normal limits [3]. In severe curvatures death may occur due to right-sided heart failure [1]. The long-term effects of mild to moderate loss of pulmonary efficiency have not been examined, but a recent study has shown that in adults, reduced exercise capacity is a more reliable predictor of mortality than diabetes, heart disease, and smoking [4]. A previous study documented a substantial increase in chest excursion in a patient who presented with severe multiregional pain and respiratory symptoms [5]. The current objective is to report reduced magnitude of curvature, and near-elimination of torso asymmetry, which occurred in correlation with the improvement in pulmonary symptoms.

366

M.C. Hawes and W.J. Brooks /Reversal of the S/#/i.v and S\mptom*

2. Case History The patient is a female born in 195') prenatal complications developed in the first trimester and birth complications (at full term) included emergency breech delivery with anoxia. Parents were advised that neurological damage was likely, but early development was normal. At age two years (Figure 1A), posture was symmetrical and balanced; by age three (Figure 1 B) and age six (Figure 1 C) increasing forward rotation of the right shoulder was apparent in casual photographs. Referral to an orthopedic surgeon was made at age 11.7 years based on obvious torso deformity; the diagnosis was thoracic scoliosis with a Cobb magnitude of 45 degrees, with a smaller lumbar curve, thoracic lordosis, pectus excavatum and mitral valve prolapse also present. Surgery was recommended strongly but was declined by the patient. Torso strengthening exercises taught by a physical therapist during a six-week period of instruction were carried out daily from 1964-1992. An obvious torso deformity was present (Figure 1D).

3.

Materials and Methods

During 1991 deep tissue massage (Corrinne Kotch, LMT, Tucson AZ) was carried out eight times in response to psychological distress associated with personal and professional strife. In February 1992 outpatient psychological therapy was initiated in response to psychological decompensation concurrent with intensive multiregional pain; daily self-therapy (4-6 h daily) for relief of pain and psychological symptoms included screaming and other emotional catharsis as well as ischemic pressure and manual traction. Daily torso strengthening exercises were discontinued. In April 1992 a noticeable improvement in torso appearance developed suddenly in correlation with decreased discomfort. A relationship with the second author initiated at this time by the patient (the first author of this study) was maintained during the next decade and included support, guidance, monitoring and documentation of changes in signs and symptoms as they developed; intervention in the form of manipulative therapy also was provided as needed. This included CMM on three occasions between 1993-1995, and on seven occasions from 1999-2000. CMM refers to the use of a broad spectrum of (in this case, direct action) manipulative medicine

367

M.C. Hawes and W.J. Brooks / Reversal of the Signs and Symptoms

techniques employed for the purpose of restoring optimal available motion to the entire musculoskeletal system, including the cranium. Techniques employed were thrusting, post-isometric relaxation stretching, articulation, myofascial release, and counterstrain. The proportionately most limited movements were identified, to which, in turn, treatment was primarily directed (WJ Brooks, unpublished). This approach differs fundamentally from methods which employ either spinal alignment, postural balance, symmetrical active range of motion, and/or symmetrical passive motion testing as sufficient markers of musculo skeletal dysfunction [7]. Torso circumference was measured directly and Cobb angle measurements were made by independent readers (Radiology Department, University of Arizona) from serial radiographs taken at four-year intervals. 4. Results Magnitude of Cobb angle for thoracic and lumbar curvatures declined progressively during the period of treatment, from 47 to 28 degrees and from 26 to 13 degrees, respectively (Table 1). Vertebrae T4-T12

1990 47±1

1994 38±2

1998 34±2

2001 28±1

L1-L4

2(H-1

19+1

17-1-1

13+1

Table 1. Changes in Cobb angle magnitude in thoracic and lumbar curvatures.

Torso asymmetry at the beginning of treatment was reflected in a >12-cm difference between circumference of the left and right sides of the ribcage (Figure 2). By the end of treatment, the difference was less than 1 cm.

Figure 2. Relationship between improved chest expansion (solid line) and improved torso deformity (broken line). 'Chest expansion was measured directly based on the difference in total chest circumference at minimum and maximum inhalation [5]; 'torso deformity* reflects left-right torso asymmetry, measured directly based on the difference between left and right ribcage from anterior and posterior midiine. Each value represents mean and standard deviation from at least 30 measurements taken over a 48-h period.

368

Af C. Hawcs und W.J. Rrooks / Reversal t>t the Sign* and Svinpronis

5. Discussion Improved signs and symptoms in longstanding, previously untreated idiopathic scoliosis occurred in response to a combination of mobilization therapies applied daily over a sustained period. The forty-percent improvement in magnitude of Cobb angle achieved in this study is in the thirty- to forty-percent range of improvement that can be obtained using spinal fusion surgery in adult scoliosis [6]. The change in curvature was correlated with a 7.5-cm increase in chest expansion, a > 10-cm reduction in torso asymmetry, and a near-elimination of pain and respiratory symptoms [5]. The fastest rate of change occurred during 1992-1995, and 1999-2000, two periods when the patient was treated with CMM. During thefirst period a range of therapies including psychotherapy, massage therapy, CMM and daily self-therapy were employed. From 1995-1999 only daily self-therapy was used. From 1999-2000 seven sessions of CMM were used in addition to daily self-therapy. The results are consistent with the possibility that CMM significantly influenced outcome when mobilization therapies were used to treat signs and symptoms of longstanding thoracic spinal deformity. References 1.

2. 3. 4. 5. 6.

7.

Bowen, R. M. 1995 Respiratory Management in Scoliosis. In Lonstein J, Bradford D, Winter R, Ogilvie J (Eds.) Moe's Textbook of Scoliosis and Other Spinal Deformities, 3rd Edition, WB Saunders, Philadelphia: 1995, pp572-580. Szeinberg, A., Canny, C.J., Rashed, N., Veneruso, G., and Levison, H. Forced VC and maximal respiratory pressures in patients with mild and moderate scoliosis. PedPu/mo,? 4: 8-12.1988. Chong, K.C., Letts, R. M., and Gumming, C. R. Influence of spinal curvature on exercise capacity. JPe'l Orthop 1: 251-254.1981 Myers, J., Prakash, M., Froelicher, V., Dat, D., Partington, S., Atwood, J.E. Exercise capacity and mortality among men referred for exercise testing. NEngUAfed346: 793-801.2002. Hawes, M.C. and Brooks, W.J. Improved chest expansion in IS after intensive, multiple modality, non surgical treatment in an adult Chest 120: 672-674. 2001. Bradford, D. S. Adult Scoliosis, In Lonstein J, Bradford D, Winter R, Ogilvie J (Eds.) Moe's Textbook of Scoliosis and Other Spinal Deformities, 3rd Edition, W.B. Saunders, Philadelphia: 1995,369-386. Kappler, R. E., Jones, J.M., and Kuchera, W.A. Diagnosis and Plan for Manual Treatment - A Prescription. In Ward, R.C. (Ed.). Foundations for Osteopathic Medicine. Williams and Wilkins, Baltimore: 1997, 483-488.

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Long-term effects of scoliosis Marc Asher, Douglas Burton Kansas University Medical Center, Kansas City, Kansas USA The focus of this presentation is adolescent idiopathic scoliosis (AIS), which is by far the most common scoliosis. It is a lifetime, incurable, and usually mild condition of unknown cause or, more likely, causes. Its natural history is generally favorable in comparison to the general population. Mortality is not increased in comparison to the non-scoliotic control population.2'3'15'18 Mortality is increased for patients with scoliosis onset during their juvenile years.15 Risk of mortality appears to be limited to patients with thoracic curves whose vital capacity is less than 45% predicted and scoliosis greater than 110° by age 15.14 Shortness of breath symptomatology occurs not only in patients with thoracic but also those with double and even occasionally with thoracolumbar curves. Severe shortness of breath does not appear in patients with curves of less than 80° and vital capacity of more than 70% predicted.18 Acute and chronic back pain is increased in comparison with the control population. However, pain does not correlate with curve pattern, curve magnitude, or the presence of osteoarthritic changes.19 Pain management does not appear to be a problem except in occasional patients who have been operated.11 Work and social histories are generally similar.9 These findings have been confirmed in a recent study in which neither work nor activity levels were different between the control group and the scoliotic group of patients at an average age of 66 years and follow-up of 44 to 61 years.19 Fortunately, most curves are small enough (less than 30°) that treatment is never needed. For patients with larger curves the treatment is conceptually unsatisfactory. Bracing is poorly tolerated and its effectiveness debated.7'12'13'16 Surgery involves the trade-off of a stiff and less curved spine for a stable and curved spine. In addition, a patient's risk of subsequent surgery is 6% to 32% at a minimum follow-up of 5 to 12 years.4'5'6'10 The lifetime risk is unknown. Primary surgery in adults is infrequently indicated. In the Iowa series it would appear to be about 8 in 203 or 4%.19 Primary degenerative spondylosis is an important and little understood co-morbidity. Subsequent surgeries following primary deformity surgery in adulthood are necessary in at least 15% of patients at a minimum follow-up of 2 to 3 years.7'17 The lifetime risk is, again, unknown. When indicated, there are several advantages for surgery during adolescence. Among the reasons are a less fixed trunk deformity, better capacity for secondary curves to compensate, and achievement of anterior column load sharing through residual growth. However, there are a number of disadvantages, including the generally kind natural history of the condition, the fact that few adults present with symptoms severe enough to warrant surgery, and the reality that a patient's co-morbidities have yet to appear.

In conclusion, when managing patients with adolescent idiopathic scoliosis, it is important to remember that it is not a fatal condition. In addition, most curves are so small that they do not require any treatment. Selection of treatment requires considerable judgment as the generally accepted treatment options have substantial shortcomings. It is becoming increasingly clear that curve size alone is not the only important factor in selecting treatment.1 Acknowledgments The authors wish to thank Terry Orrick, academic secretary, and Barbara Funk, editor, for their assistance in the preparation of this manuscript. This study was supported in part by the Scoliosis Research Fund, Kansas University Surgical Association. CONFLICT OF INTEREST DISCLOSURE: See Asher et al: Trunk deformity correction stability... This volume. References 1.

2. 3. 4.

5.

6. 7. 8.

9. 10.

11. 12.

Asher, M.A.; Lai, S.M.; Burton, D.; and Manna, B.: Discrimination Validity of the Scoliosis Research Society-22 Patient Questionnaire: Relationship to idiopathic scoliosis curve pattern and curve size. Spine (Accepted) Branthwaite, M.A.: Cardiorespiratory consequences of unfused idiopathic scoliosis. Br J Dis Chest 80:360-369, 1986. Collis, O.K.; Ponseti, I.V.: Long-term follow up of patients with idiopathic scoliosis not treated surgically. J Bone Joint Surg 51-A:425-445, 1969 (12). Connolly, P.J.; Von Schroeder, H.P.; Johnson, G.E.; and Kostuik, J.P.: Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine. J Bone Joint Surg 77-A:1210-1216, 1995 (14). Danielsson, A.J.; Nachemson, A.L.: Radiographic findings and curve progression twenty-two years after treatment for adolescent idiopathic scoliosis-Comparison of brace and surgical treatment and with a matching control group of straight individuals. Spine 26:516-525,2001. Dickson, J.H.; Erwin, W.D.; Rossi, D.: Harrington instrumentation and arthrodesis for idiopathic scoliosis: A twenty-one year follow up. J Bone Joint Surg 72-A:678-683, 1990 (18). Dickson, J.H.; Mirkovic, S.; Noble, P.C.; Nalty, T.; and Erwin, W.: Results of operative treatment of idiopathic scoliosis in adults. J Bone Joint Surg 77-A: 513-523, 1995. Goldberg, C.J.; Dowling, F.E.; Hall, J.E.; and Emans, J.B.: A statistical comparison between natural history of idiopathic scoliosis and brace treatment in skeletally immature adolescent girls. Spine 18:902-908, 1993. Harol J: The clinical appearance of low back disorders in the city of Goteberg, Sweden. Acta Orthop Scand M8{Suppl}, 1969 Lenke, L.G.; Bridwell, K.H.; Blanke, K..; Baldus, C.; Weston, J.: Radiographic results of arthrodesis with Cotrel-Dubousset instrumentation for the treatment of adolescent idiopathic scoliosis: A five to ten year follow up study. J Bone Joint Surg 80A.-807-814,1998. Mayo, N.E.; Goldberg, M.S.; Poitras, B.; Scott, S.; Hanley, J.: The Ste-Justine Idiopathic Scoliosis Cohort Study. Part III: Back pain. Spine: 19:1573-1581, 1994. Nachemson, A.L.; Peterson, L-E.; and members of the brace study group of the scoliosis research society: Effectiveness of treatment with a brace in girls who had adolescent idiopathic scoliosis. J Bone Joint Surg 77-A: 815-822, 1995.

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13.

Noonan K.J.; Dolan, L.A. Jacobson, W.C.; and Weinstein, S.L.: Long-term psychosocial characteristics of patients treatment for idiopathic scoliosis. J Pediatr Orthop 17:712-717 1997.

14.

Pehrsson, K.; Blake, B.; Larsson, S.; Nachemson, A.: Lung function in adult idiopathic scoliosis: A 20 year follow up. Thorax 46:474-478,1991. Pehrsson, K.; Larsson, S.; Oden, A.; and Nachemson, A.: Long-term follow-up of patients treated with untreated scoliosis. A study of mortality, causes of death, and symptoms. Spine 17(9): 10911096,1992. Rowe, D.E.; Bernstein, S.M.; Riddick, M.F.; Adler, F.; Emans, J.B.; and Gardner-Bonneau, D.: A meta-analysis of the efficacy of non-operative treatment for idiopathic scoliosis. J Bone Joint Surg 19-A:664, 1997. Sponsellor, P.D.; Cohen, M.S.; Nachemson, A.L.; Hall, I.E.; Wohl, M.B.: Results of surgical treatment of adults with idiopathic scoliosis. J Bone Joint Surg 69A:667-675,1987 (78). Weinstein, S.L.; Zavala, D.C.; Ponseti, I.V.: Idiopathic scoliosis. Long term follow up and prognosis in untreated patients. J Bone Joint Surg 63A:702-712,1981. Weinstein, S.L.: Long term follow-up of pediatric orthopaedic conditions: Natural history and outcomes of treatment. J Bone Joint Surg 82-A: 980-990,2000.

15.

16.

17. 18. 19.

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Quantitative Measurement of Spinal Brace Use and Compliance in the Treatment of Adolescent Idiopathic Scoliosis G.P. Nicholson1; M.W. Ferguson-Pell1; K. Smith2; M. Edgar2; T. Morley2

1. Centre for Disability Research and Innovation, Institute of Orthopaedics and Musculo Skeletal Sciences, University College London, Brockley Hill, Stanmore, HA 7 4LP. 2. Royal National Orthopaedic Hospital Trust, Brockley Hill, Stanmore , UK, HA 7 4LP.

Sources of support: RNOH Board of Clinical Studies and ASPIRE

Abstract. The objective measurement of compliance with spinal bracing in adolescents with idiopathic scoliosis (AIS) is fundamental in the validation of clinical trials of bracing effectiveness, and in helping clinicians better understand reasons behind poor compliance. Current technology has been developed and tested for discrete, reliable and objective measurement of the times of day a brace is worn and consistency in its use. TLSOs were instrumented with data loggers measuring temperature at the skin/brace interface at 16 minutes intervals over a period of 88 days; between routine follow up and without patient interference. 10 female patients (age 14 years, sd 1.1) with AIS using spinal bracing as part of their treatment regime took part in the study over 15 months. Skin/brace interface temperature during periods of wear in the UK was >30°C, ambient 23°C, sd 4. Compliance ranged from 8-90%, average 65%. Patients tended to over estimate their compliance by ISO % (sd 50%). There was no significant difference between weekday and weekend compliance but wear patterns differed. Nightwear was significantly greater than daywear. Patients with very good compliance only removed their brace for washing or exercise periods but where poor compliance was evident, the brace was only worn sporadically during the day. Temperature provides a clear signal of brace use and can be used for long-term data logging using discrete instrumentation, providing a tool to help identify and understand the reasons behind poor compliance.

1. Introduction

Adolescent Idiopathic scoliosis (AIS) is a deformity of the spine, characterised by lateral curvature and vertebral rotation; cause still unknown. It is in danger of progressing during the years of greatest skeletal growth and if left untreated will cause increased symptoms, especially those involving the respiratory system. Conservative treatment consists of regular monitoring using observation and radiography to assess progression of the deformity, and if warranted spinal bracing to try and prevent it from

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worsening and so prevent surgery. Currently, clinicians specify that braces should be worn for 20-23 hours a day. However, there is little objective evidence to recommend the actual number of hours a brace should be worn. The accurate measurement of compliance with this treatment regime is fundamental in validating clinical trials of bracing effectiveness, and help clinicians understand reason's for non-compliance. Wearing a brace isn't fashionable, restricts movement and may be uncomfortable, especially as the patient grows out of the brace. Historically, the "time in brace" has been measured subjectively by questionnaire, interview, or for signs of brace wear and fatigue. This has suggested 38100% of patients in the studies complied with their prescribed regime1"2 and actual compliance ranged between 58-98%3' . From such information the clinician could only make subjective judgement upon whether compliance was adequate, realising this information may not be particularly accurate. It also made it extremely difficult to show any significance in trials on the effectiveness of bracing, especially when comparing full time and part time use. In recent years several quantitative techniques have been used to measure compliance. These included skin/brace interface temperature5, strap tension4 and skin/brace interface force6'7. This work has shown that actual time in brace is less than reported by the user and clinical judgment of brace use is not a reliable way to distinguish between compliant and non-compliant users. However, doubts have been expressed as to the validity of these quantitative methods. Point force measurement cannot reliably distinguish whether zero force indicates no brace use or the sensor is unloaded when the brace is being worn. These devices are generally too bulky for discrete long term monitoring or require permanent connection to a computer, limiting their use to laboratory devices or short-term (days) remote data loggers, requiring intervention by the patient. Temperature measurement at the skin/brace interface5 gave an unambiguous signal of time in brace but did not record information on daily use. As technology has evolved it is now possible to develop smaller discrete temperature data loggers with large memory capacity and high sampling frequency. This paper presents work on developing and testing these devices to measure the times of day the brace is worn and consistency in using the brace. 2. Methods The "time in brace" was determined by monitoring the skin/brace interface temperature. Bracing materials have poor thermal conductivity and the temperature will be similar to body temperature, and very different from ambient temperature, especially in the UK. Two data loggers were tested, each comprised sensor, real time clock, memory and power source. Their size did not affect the efficacy of the brace nor change its appearance, were acceptable to the patient and did not interfere with their daily routine. They also withstood harsh treatment such as washing and being dropped. A HOBO H8 temperature data logger (Onset Computer Corporation, MA, USA), modified to reduce its size to 70x45x6 mm, was placed in a hole cut in the back of the brace and sandwiched between two layers of closed cell foam, the inner one being

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perforated to allow air to circulate. The logger was wrapped in aluminium foil and a liquid proof/vapour permeable membrane to protect it from electromagnetic interference, static, and washing. 7920 date/time stamped points were logged at 16 minutes intervals over a period of 88 days. The data logger was fitted, launched and the data downloaded at normal routine visits to the orthotics department, not extending the visit by more than 15 minutes. 10 female subjects (average age 15 yrs, sd 1.2) with AIS (Thoraco-lumbar) took part in the study over a period of 14 months, sd 4.5. Actual logging time spread over this period was 3.4 months, sd 1.2. The subjects had a period of scoliosis 29 months, sd 22, and had been in bracing 16 months ± sd 9.5. The average number of braces was 3 (sd 1.3) and average period between braces 8 months, sd 7.3. IButton Thermochron data loggers (Dallas Semiconductors, CA, USA) were compared with the HOBO devices on a single patient and a trial is underway to assess suitability for long term monitoring in terms of reliability and patient acceptability. The iButtons are very small devices in environmentally sealed cans, 17mm diameter by 6-mm thick, and fitted to the brace in the same manner as a rivet. These loggers store up to 2048 date/time stamped values, but can be wired together to increase it, and can also store up to 65,536 temperature values as a histogram giving compliance only information. 3. Results Temperature at the skin/brace interface was 32.8°C (sd 1.6°C) and a clear threshold for time in brace was 30°C (e.g. Fig 1), unworn brace temperature was 23.3°C (sd 3.6°C). Compliance with the treatment regime was determined by dividing the measured hours worn with the time specified by the clinician for the brace to be worn. The average weekly compliance was 65% (sd 25%), range 8%-90% (Table 1). For all subjects there was no significant difference between weekday and weekend wear compliance (Student paired t-test, P>0.05). For all subject data there was a significant difference (Student paired t-test, P<0.005) between night and day time wear. 7 out 10 subjects said they wore their brace as prescribed and the average measured compliance was actually 70% (sd 18%) of the subject's estimated compliance; range 37%-90%. Time worn at each logged interval in a day (averaged over the recording period)

35

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j* \ ft > f \ d

)

V

V

* *n i 1 |W

Tim. (24 hn)

Figure 1. Daily use for a single subject

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was presented as the percentage of the total time worn, to show the distribution of a subject's brace use throughout the day. It was clear how daily use patterns vary between subjects. For example, subject 1 (Fig. 2) had good compliance (93%) removing their brace only for short periods in the mornings and evenings (for washing perhaps). Subject 2 had much poorer compliance (8%), only using their brace at night. For all subjects in this study it was clear there was very good brace use at night times. Where poor compliance was evident it was during the day that brace use varied. Table 1. Compliance data (*Monday 7am to Friday 10pm; **Friday 10pm to Monday 7am; *7am to 10pm; **10pm to 7am). (error 95% confidence limits) Use Week Actual/ Weekly Week Day Night Estimated/ hrs/day day* end** Estimated time* time** prescribed Avg 20-23 65% 66% 63% 80% 89% 70% 55% 14 20 19 21 24 18 20 95% 18-94 Range 8-90 11-90 37-90 2-91 1-91 22-100

iButton and HOBO data loggers both produced similar temperature profiles. The HOBO recorded time/date stamped values over a period four times longer than the iButton. However, the iButton stored ~8 times more temperature values without time/date stamps in a histogram, giving information on total compliance over a much longer period. The iButton was more easily fitted in a shorter time and was less obtrusive. There was no difference in launch and download times. The iButton did not cease logging if interrogated mid capture period whereas the HOBO did. The iButton was substantially cheaper than a HOBO H8 temperature logger. 4. Discussion Current temperature data logging technology was used to measure skin/brace temperature at regular date/time intervals providing information on daily use patterns and compliance between routine follow-ups. In the UK, ambient temperature rarely rises above 25°C and with a skin/brace temperature >30°C this clearly indicated the "time in brace". The average compliance measured in this paper was 65%, closely matching previous studies. The patient's estimated compliance was 89%, tending to overestimate by as much as 200%. However, it was apparent the patient was not deliberately misleading but attempted to judge compliance accurately, admitting poor compliance where applicable.

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There was no significant difference in average compliance between weekday and weekend wear. However, closer examination of the daily wear profiles showed there was an observed difference in use patterns. For example, it was clear that at weekends some patients had a greater lie in period in the morning and wore the brace less during the rest of the day. There was a significant difference between average daytime and night time wear, primarily due to the large differences for individuals with compliance <80%.

Time of day (hours)

Time of day (hours)

Figure 2. Average daily use patterns from midnight to midnight. Displayed as the % of time worn, at each logged interval in a day, of the total time worn.

Full time, 20-23 hours a day, wear regimes are being challenged, and part time (16 hrs/day) regimes are being prescribed. Clinical studies have suggested that night time only wearing using "specialist braces" is as good as part time brace wearing. However, there is little objective data on compliance in these studies to adequately assess what is part time and what is full time wear. If average compliance is 65% with full time use, then the patients on average can be considered to be part time wearers anyway. There was no obvious difference between the compliance of patients with 20 and 23 hrs/day regimes, with the limited patient numbers used in this trial. If a TLSO is intended for full time brace use then its biomechanics are designed for constant displacement when standing or moving erect. If there is poor compliance and night time wear is significantly greater than day time wear, this forms a large part of their treatment regime, and the efficacy of the brace may be compromised and not as intended. The measure of compliance gives a good indication of whether a patient accepts their treatment regime. Measuring daily brace use patterns over long periods can also be important in tracking an individual's bracing habits, i.e. when being introduced to a new brace or being weaned from it (Fig 1). When poor compliance is a problem, in combination with patient interviews, such information can help understand the reasons why. In this study it was apparent that where there was poor compliance the patient clearly took their brace off during the most socially important hours of the day, i.e. when fashion was most important. During school hours this was not such an issue as some

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patients said their uniform adequately hid their brace. Others suggested they had an understanding peer group and felt confident wearing their brace within it. As technology and hardware has advanced there is now the provision for all spinal braces to be cheaply and discretely instrumented with temperature data loggers for measuring compliance that does not require patient interference. These devices can now be communicated with using handheld personal digital assistants (PDAs) making them an ideal tool for making clinical judgements or for research purposes. References 1.

Climent JM and Sanchez J. Impact of the type of brace on the quality of life of Adolescents with Spine Deformities. Spine 24 (1999) 1903-1908.

2.

Gurnham RM. Adolescent compliance with spinal brace wear. Orthopedic Nursing2 (1983) 17.

3.

DiRaimondo CV and Green NE. Brace-wear compliance in patients with adolescent idiopathic scoliosis. J.Pediatr.Orthop.*(\WS) 143-146.

4.

Vandal S, Rivard CH, and Bradet R. Measuring the compliance behavior of adolescents wearing orthopedic braces. Issues Compr.Pediatr.Nurs. 22 (1999) 59-73.

5.

Lavelle J, Smith K, Platts R, Morley T, Ransford AO, and Edgar MA. An Assessment of Brace Compliance in Adolescent Idiopathic Scoliosis using a New Brace Timer. J.Bone Joint Surg.Br. 78-B (1996) 162.

6.

Houghton GR, Mclnerney A, and Tew A. Brace compliance in adolescent idiopathic scoliosis. Spine 14 (1989)42.

7.

Lou E et al. A Load Compliance Monitor System for the Treatment of Scoliosis. Proceedings of IEEE Canadian Conference on Electrical and Computer Engineering, Edmonton, Canada, 1999, pplSOl-1505

7/i.B Grivas lEti) Research into Spinal Deformities 4 1OS Press. 2002

Is The Boston Brace Mechanically Effective in AIS? VJ Raso, E. Lou, DL Hill, JK Mahood, MJ Moreau Capital Health Authority, Glenrose Site, 10230-111 Ave Edmonton AB, Canada T5G OB7 email: [email protected] Abstract The application of three-point loading is thought to be the essential basis for effective bracing of adolescent idiopathic scoliosis. Care is taken to ensure that active pressure pad is located to provide maximum support to the apex of the scoliosis while minimizing its lordosising effect. Paradoxically, while cited as an essential factor in the design of braces, there is no consensus as to the importance of such loading to the clinical effectiveness of braces. It may be that braces are effective but that they are effective for reasons unrelated to mechanics. There are few studies that link brace mechanics and change in spinal alignment. Optimal bracing for AIS requires a much better understanding of the role of the mechanical support of braces used to treat AIS. Sixteen subjects, 3 males and 13 females, were participated to this study to determine the correlation between quantity and quality of brace wear and treatment outcomes in AIS. This study showed that the target force levels set for the active pad in braces prescribed for the treatment of AIS vary considerably and that brace applies the desired load 25% of the prescribed time.

1. Introduction There are few non-surgical treatment options for children with potentially progressive spinal deformity. Bracing is the most commonly used treatment. However, the effectiveness of bracing is uncertain [1,2]. Opinion concerning the effectiveness of braces turns on two points: do patients wear the brace as prescribed and is the correction due to mechanical support. To determine how often a patient wears her brace, the most commonly accepted methods are to ask the family if the brace is being used and to visually inspect for signs of wear. In-lab studies have been done to determine the mechanical loads imposed by a brace, many. Willner [3] found that lateral forces are more important than elongation forces to the correction of spinal deformities. Dansereau et al [4] found that the biomechanical action of braces aggravates the deformity in the lateral plane by increasing thoracic hypokyphosis. The nature of the loads in terms of magnitude and direction generated by the brace is still not clear [5]. Jiang et al [6] measured the magnitude, location and direction of pressures as well as the forces imposed by the straps, and found that there was considerable variation in how braces are worn by patients. Some children secured the brace very aggressively and imposed high loads on their trunks; other children wore the brace loosely and imposed low pressures. However, all of these studies were done under laboratory environment. To determine the relation

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between quantity and quality of brace wear and treatment outcomes in AIS, load measurements outside laboratory environment must be done. 2. Objective The purpose of this study was to determine the temporal pattern offerees exerted by the main pressure pad in Boston braces prescribed for AIS. 3. Methods and Materials A portable, battery-powered data logger was developed to measure the force exerted by the primary brace pad during daily activities [7]. The device consisted of a data logger and a force transducer (FS01, SenSym Inc.) (Figure la & b). The operating force range of the transducer was 0 - 6.82N. The force transducer was embedded in the active pad under the lining of the brace. The data logger was 5.5cm x 8.0cm x 2cm and weighed about 25g. It was attached to the brace either with velcro or carried by the patient. The prescribed (target) pad load was set by his/her physician after the force transducer was installed, and recorded by the data logger. The data logger performed two functions: 1) stored the collected data and 2) provided feedback to the patients. It had a force level indicator consisting of one green and two red light emitted diodes (LED) that informed patients regarding how well they secured their braces: the high (H) red LED indicated pad load above 120% of the prescribed level, the green LED indicated load within 80 to 120% of the prescribed level, and the low (L) red LED indicated load was below 80% of the prescribed level. Forces were subdivided between daytime and nighttime of the day. Daytime was defined as 07:01 - 23:00, and nighttime was defined as 23:01-07:00. 4. Clinical Study Sixteen brace candidates who were prescribed Boston braces, 3 males and 13 females age 13.6±1.8 years, who have worn their braces from a few months up to 1 year were selected. The selection criteria were 1) diagnosis of idiopathic scoliosis, 2) ages between 9 - 1 5 years and 3) prescribed brace treatment. The exclusion criteria were anyone who 1) had other musculoskeletal or neurological disorders, 2) refused to wear the brace, 3) was being weaned from treatment, or 4) was a surgical candidate. The Cobb angles of the subjects with pre-brace and in-brace at time of monitoring were 35° ± 9° and 31° ± 13°respectively (4 subjects did not have Cobb angles recorded). Each subject used the indicator on the device to adjust the tightness of the brace to achieve the prescribed pad load. Loads were measured in the laboratory when each subject executed 8 movements: normal standing, bending forward and backward, bending to the left and to the right, sitting normally, sitting with support and holding breath (sample rate: 0.5 sample/second and 10 samples taken). These measurements verified the device was functioning properly, served as a training session for the subjects, and showed them how various postures and activities affected the amount of loads applied by their braces.

3X0

I•'../. Ra.w ct til. //.s the Ho^lon Brace Mcch
These subjects then carried on with his/her normal daily activities, returning in 1 to 16 days. One sample was taken every minute. The data were downloaded from the data logger and analyzed omn a PC.

Figure la. The data-logger with the force sensor. Figure Ib. The force transducer inside a boston Brace. 5. Results

Sixteen subjects were selected to study the quality and quantity of brace wear pattern during their treatment period. The average prescribed force was 1.2 ± 0.6N and the average prescribed time was 22.3 ± 1.3 hours. Figure 2 shows the variation of the prescribed pad force of each subject. The average recorded force and time were 1.3±0.7N and 14.7 ± 2.5 hours. The average force was 1.5 ± 0.23N during daytime and 0.37 ± 0.17N during nighttime. On average, brace was worn 68% of the prescribed time (22.3 ±1.3 hours) per day. When the brace was worn, the force level was below 80%, between 80 to 120%, and above 120% of the prescribed level 7.8 hours, 3.3 hours, and 3.6 hours, respectively. The percentages of the prescribed time that the forces level was below 80%, between 80 to 120%, and above 120% of the prescribed level were 35 ± 21%, 16 ± 17% and 17 ± 14%, respectively. Loads were always higher on the first 15 minutes when subject donned on her brace. The brace was worn 50% of the wear time with a force level below 80% of the prescribed level. Figure 3 summarized the quantity and quality of brace wear of the 16 subjects per day.

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Figure 2. The prescribed load level. versus brace load.

Figure 3. Average time wore

6. Discussion Although bracing is currently favored as a means to treat children with moderate scoliosis, it remains controversial despite 40 years of clinical experience. There are many reasons for this state. One may be due to the compliance of brace users. Adolescents with scoliosis usually wear their braces less than the prescribed time. But the chief among them is the ignorance that continues concerning the role of brace mechanics in the success of treatment. Successful bracing may not require significant interface forces; if so, novel less intrusive braces may be developed that are equally efficacious. If success is predicated on effective brace/trunk mechanics, then more comprehensive information on the mechanical action of braces is essential to the optimal prescription of this mode of treatment. 7. Conclusion Bracing may be an effective treatment for AIS but its mechanical basis needs to be better understood. This study showed that the target force levels set for the active pad in braces prescribed for the treatment of AIS vary considerably. 8. Acknowledgements Glenrose Rehabilitation Research Program Edmonton Orthopaedic Research Fund Dr. Scott Mubarak & Michelle Marks - Children's Hospital of San Diego

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References 1. 2. 3. 4.

5.

6. 7

R. G. Houghton et al., Monitoring True Brace Compliance. Proceedings of the 21st. Meeting of the Scoliosis Research Society, Hamilton, 21 -25 September 1986, 101. M. Ylikoski et al., Biological Factors and Predictability of Bracing in Adolescent Idiopathic Scoliosis. J Pediatric Orthopedics (9)1989,680-683. S. Willner, The effect of the Boston brace on the frontal and sagittal curves of the spine. Ada Orthop Scand, 55 (1984), 457-460. J. Dansereau et al., Boston Brace Treatment: 3-D Immediate Effect on the Thoracic Scoliotic Spine. Proceedings Int'l Symposium on 3-D Scoliotic Deformities, Montreal, 27-30 June 1992, 312-316. B. Cote et al., A method for the Measurement of the Boston Brace Biomechanical Action on Scoliotic Deformities. Proceedings Int'l Symposium on 3-D Scoliotic Deformities, Montreal, 2730 June 1992, 81-88. H. Jiang et al., Interface Pressures in the Boston Brace Treatment for Scoliosis. Proceedings Int'l Symposium on 3-D Scoliotic Deformities, Montreal, 27-30 June 1992, 395-399. E. Lou et al., The Daily Force Pattern of Spinal Orthoses in subject with Adolescent Idiopathic Scoliosis. Prosthetics andOrthotics International, 26, (2002) 59-63.

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A Wearable Networked Embedded System for the Treatment of Scoliosis Michael Bazzarelli1, Nelson Durdle1, Edmond Lou , James Raso , Doug Hill l

Dept. of Electrical Engineering, University of Alberta, Edmonton, Alberta, Canada ^Department of Rehabilitation Technology, CHA-Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada bazzar@ee. ualberta. ca Abstract. In order to study a physiotherapeutic approach to idiopathic scoliosis treatment a posture monitoring system is being built. The system is a small, lightweight, fully portable system capable of monitoring and providing feedback to a patient regarding their posture. Using the combination of accelerometer and electromagnetic technology, distance and angle measurements can be obtained for receivers placed strategically on the patient's back. This data is recorded for further analysis of the patient's progress and to provide immediate feedback to the patient on the status of their posture. Preliminary testing has shown that angular changes of one degree can be detected by the system and that the speed of the electromagnetic field detection has been increased ten times greater than the previous architecture.

1. Introduction Idiopathic scoliosis is a spinal deformity producing a characteristic 'S' shaped curve. The most common nonsurgical treatment is bracing. Some problems involved with spinal orthoses are their cosmetic appearance, possibility for incorrect usage, and physical irritation and annoyance. A therapeutic treatment of idiopathic scoliosis has been proposed that would imitate the active component of brace treatment, that being, the pressure exerted by the brace on the patient reminds him to move his body into the correct postural position. We are developing a system for this treatment method. It is a wearable computer that monitors the posture of the patient, provides feedback for correction, and monitors progress. It is less restrictive and more cosmetically appealing than the brace. Furthermore, defects in proprioceptive postural control have been suggested as a causative factor of spinal asymmetry. In this case, our system would aid in correcting the suggested misinterpretation of the body's posture. There have been other systems developed for tracking motion. Our system can track in more than one dimension, therefore, allowing us to obtain more useful information. In comparison to the more sophisticated six degrees of freedom (6DOF) and 3DOF systems, our system is fully portable and can be worn by the patient during his daily activities. The posture monitoring system introduces parallel processing, networking, and accelerometer technology to increase the system speed and resolution over our previous system. This paper presents an overview of a posture measurement system, nearing completion, for the treatment of idiopathic scoliosis and the theoretical issues involved with determining the posture of a person.

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2. Requirements A posture monitoring system has several important requirements. Idiopathic scoliosis effects adolescents so there is a range of torso sizes. The system must be light weight, small, and it must be able to measure the range of torso sizes. Reducing the system's power requirements allows for longer system operation and reduces battery weight. 3. Materials and Methods 3.1 System Overview The systems consists of a master control unit, one electromagnetic (EM) transmitter, and several receivers. The unit is worn by the patient in a configuration that best facilitates the optimal monitoring of their particular defective posture. The master control unit can be clipped to the patient's belt and the transmitter located at the base of their spine. A variable number of receivers are then placed at different points on the patient's back. The receivers are capable of measuring pitch and roll using accelerometers. The distance to the transmitter is determined using a coil for EM field detection. A software controlled gain circuit allows the system to be used over various torso size ranges without changes to hardware. Each receiver is on a communications network with the master control unit. A microcontroller allows the receivers to collect data in parallel removing the delays associated with a polling architecture and speeding up system performance. The network protocol facilitates a future change to a wireless system. The EM transmitter uses a microcontroller, analog circuit, and custom designed orthogonal coils to generate the EM field[2]. The microcontroller allows the transmitter to autonomously generate three different EM fields with the benefit of using software to change system variables. The master control unit orchestrates data collection and processes the obtained data for storage and for feedback to the patient. 3.2 Posture Measurement Once the measurements have been obtained, they can be used to determine the patient's posture. The algorithms to do this can be optimized by considering specifically the movements that the system will need to detect in our application. Further simplification can be obtained from the known geometry of the sensors positioned on the back. Tailoring the calculations to our application removes intermediate calculations such as determining polar coordinates which still have to be mapped to a predefined incorrect posture location. There are three sources that contribute to the possible motions of the torso. Those being shoulder motions, spine movements, and hip movements. In order to detect the patient's posture all of these movements must be detectable by the system. The positions are pictured in figures 1 and 2. When considering the scoliotic patient there are six topographical features of the trunk defined that can be used to assess the patient objectively: shoulder-height differences, decompensation, scapula asymmetry, waist asymmetry, pelvis asymmetry, and shoulder-angle asymmetry. These measures are used to predict the overall impression of trunk deformity and can be used to evaluate treatment outcomes.

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Top Shoulders

Spine Front Pelvis

Shoulder Elevation Shoulder Depression Figure 1: Shoulder movements to be detected for posture monitoring.

Figure 2: Spine movements to be detected for posture monitoring.

From the data obtained by the system's sensors each type of torso movement can be measured and the appropriate feedback provided to the patient. The six topographical features of a scoliotic patient can be calculated later since this data is stored for treatment monitoring and is not used for immediate feedback to the patient. The benefit of this approach is being able to obtain data that allows us to quickly inform the patient that their posture is incorrect and to store the data for future processing and clinical use. Depending on the amount of detail that is fed back to the patients, not all the sensor data has to be processed. For example, if a single discrete incorrect posture signal is used, all the shoulder and spine movements can be determined from the distance measurements alone. Angle measurements alone would detect everything except certain cases of scapular protraction and retraction, and decompensation. The particular postural correction the patient requires determines the receiver and transmitter placement and which measures of trunk distortion that can be calculated. In order to calculate the measures of trunk distortion, both the distance and angle measurements are used from different receiver and transmitter orientations. For example, shoulder-height differences can be measured using receivers mounted on the shoulders and a transmitter either at the base of the spine or at the top of the thoracic spine as illustrated in figure 3. The height (h) that the shoulder is below the horizontal can be calculated using the measured distance (r) from the transmitter (TX) by the receiver (RX), and the angle (i) from the receiver. The formula is h = r sin i. The angle also gives us the shoulder-angle asymmetry measurement.

Figure 3: Shoulder-height difference measurement shown with lateral flexion.

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4. Results Although the system is not complete some results have been obtained. The receivers EM signal acquisition occurs ten times faster than the previous system and the number of EM measurements has been reduced. The EM signal acquisition circuitry was verified to have less than 1 % error. The angle measurement circuit was able to measure changes of one degree. 5. Conclusion An accurate, fully portable, posture monitor is being built to both monitor and record the scoliotic patient's progress. It will provide feedback to the patient to allow them to use a physiotherapeutic treatment for idiopathic scoliosis. References 1. 2. 3. 4. 5. 6.

C.T. Price et al., Nighttime Bracing for Adolescent Idiopathic Scoliosis with the Charleston Bending Brace, Spine 15(12) (1990) 1294-1299. E. Lou, An EM Approach to the Treatment of Scoliosis, Ph.D. Dissertation. University of Alberta, 1998. W. Keessen, et al., Proprioceptive Accuracy in Idiopathic Scoliosis, Spine 17(2) (1992) 149-155. D.R. Huston, et al., Smart Structures Technology and Biomechanics Research. In: Proceedings of the SPIE The International Society for Optical Engineering, Bellingham, USA, 19%, pp. 523-529. B. Dworkin, et al.. Behavioral Method for the Treatment of Idiopathic Scoliosis. In: Proc. Natl. Acad. Science, USA, 1985, pp. 2493-2497. V.J. Raso, et al., Trunk Distortion in Adolescent Idiopathic Scoliosis, Journal of Pediairic Orthopaedics 8(2) (1998) 222-226.

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Curve Progression and Spinal Growth in Brace Treated Idiopathic Scoliosis DJ Wever KA Tonseth, AG Veldhuizen Department of Orthopaedics, University Hospital Groningen P.O. Box 30.001, 9700 RB Groningen The Netherlands Tel. +31 50-3612802, Fax. +31 50-3611737 [email protected]

1. Introduction The main concern in the patient with idiopathic scoliosis relates to curve progression and resulting cosmetic deformity. It is known that the risk of curve progression is correlated primarily to periods of rapid skeletal growth. Factors that are related to growth potential, such as patient age at the time of diagnosis, status of menarche, and Risser sign proved to be important predictors of the progression of scoliosis1>2. Bracing is currently the accepted nonoperative treatment to prevent curve progression in mild to moderate scoliosis during the growth period. Corresponding to the natural history of untreated curves, Lonstein and Winter3 found a relationship between the final outcome of brace treatment and curve factors and factors that predict future skeletal growth. Factors that predict potential remaining skeletal growth do not always predict spinal growth correctly. Only a few studies have concentrated on the correlation between direct radiologic measurements of spinal growth and the progression of the scoliotic curve4. The present study evaluated the velocity of spinal growth, measured with the length of the scoliotic spine on longitudinal series radiographs, and its relationship to the progression of the scoliotic curve. Progression is evaluated in terms of Cobb angle, lateral deviation, and axial rotation increase in the period before brace therapy and during the time the brace was worn.

2. Materials and methods Patient group The longitudinal study was based on measurements made on conventional standing anteroposterior (AP) radiographs of 54 girls with adolescent idiopathic scoliosis. In all patients, a Boston brace was prescribed during the followup period. This brace treatment was indicated in skeletally immature patients with a Cobb angle between 20°

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and 45°. Patients who underwent surgical procedures performed during the followup period were excluded from the study. Radiographs of the patients from their first visit to the clinic until skeletal growth was completed were used for the study. The mean age of the patients at diagnosis was 11.1 (standard deviation, 2.01 years). All had a major thoracic curve with the apex between T6 and T12. The mean Cobb angle on the first radiographs of the thoracic curves was 25.9° (standard deviation, 8.69°). Subsequent radiographs were taken at 4 to 6 month intervals with the patients in the standing position using the same standardized method. Radiological measurements For the radiographic measurements, six landmarks per vertebra on each AP radiograph were identified and marked with a fine white ink pen (point size: 0.4 mm). These landmarks were positioned at the corners of the vertebral bodies and the inner edges of both pedicles from Tl to L4. The corners of the vertebrae were determined by means of tangent lines through the upper and lower endplates and both lateral sides of the vertebrae. The landmarks were scanned with a MX5 CCD camera (Adimec, Eindhoven) and digitized with the Bioscan OPTIMAS* (V4.1, Bioscan Inc, Washington, Virginia) software package. The accuracy of identifying the anatomic landmarks was assessed in 20 radiographs taken at random during the study. The average variability of the digitized landmarks was 0.42 mm for the horizontal coordinates and 0.75 mm for the vertical coordinates. With the two-dimensional coordinates of the landmarks, the midpoints of the vertebral bodies and the lateral tilt of the upper and lower end plates of each vertebra were calculated by a computer algorithm. The lateral deviation for each vertebra was measured as the distance between the calculated midpoint of the vertebral bodies and the line passing through the centers of the upper end plate of Tl and the lower end plate of L4. The axial rotation was determined with a method adapted from Stokes et als. The length of the scoliotic spine was determined through the distance of the line through the midpoints of all vertebrae and discs between the upper end plate of Tl and the lower end plate of L4. All these measured dimensions on the AP radiographs have been corrected for the magnification. The spinal length measured on two consecutive radiographs, was used to calculate the growth velocity in millimeters per year. With these data, a spinal growth velocity curve was determined for each patient during the followup period. Subsequently, the followup period was divided into three phases, a phase of rapid spinal growth, a phase of moderate growth, and a phase of little or no spinal growth. On the basis of the mean spinal growth velocity values of all 54 female patients in the study, these three phases were quantified. In the various growth phases the mean increase of the Cobb angle, the mean increase of the lateral deviation, and the mean increase of the axial rotation were determined. A distinction was made between curve progression rate before brace treatment and curve progression during brace treatment.

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3. Results Spinal gowth velocity The median, fifth, twenty-fifth, seventy-fifth and ninety-fifth percentiles of the spinal growth velocity of the female patients, fitted with a third-grade polynomial (r2 = 0.93) are presented Figure 1. The maximum spinal growth velocity of the female patients was found to be between the ages of 11.5 and 12.5 years. The mean maximum growth velocity was 18.3 mm per year which extended from approximately 10 to 30 mm per year. The remaining growth of T1-L4 versus age, derived from the growth velocity rates of the patients in this study is presented in Figure 2. On the basis of the spinal growth velocity curve of the female patients, the period of the most rapid growth was defined as the period in which spinal growth exceeded 20 mm per year, the period with moderate growth as the period with a growth velocity between 10 and 20 mm per year, and the period with the least rapid growth as the period in which the growth velocity did not exceed 10 mm per year. Progression rate The mean progression rate of the Cobb angle, lateral deviation, and axial rotation of the thoracic curve of all patients in the three growth phases is presented in Table 1. A distinction has been made between the progression rate in the period before brace treatment and the progression rate during brace treatment. The mean progression rate in the phase of little growth was found to be significantly smaller compared with the mean progression rate in the phases with moderate and a large spinal growth velocity. This observation was valid for the Cobb angle, the lateral deviation, and the axial rotation increase. A significantly smaller mean progression rate of the Cobb angle was observed in the group which was treated with a brace than in the group which had not yet been treated with a brace. This brace effect could not be seen in the progression rate of the lateral deviation and axial rotation. 4. Discussion In this study, spinal growth was measured with the length increase of the scoliotic spine (T1-L4) on longitudinal standing AP radiographs. A significantly greater average progression rate of the scoliotic thoracic curve was found in the periods with rapid to moderate growth (> 10 mm per year) compared with the periods with small or no growth (< 10 mm per year). The difference in progression rates concerned the increase of the Cobb angle and the increase of the lateral deviation and axial rotation. Despite curve progression during the growth periods, the brace treatment had a significant effect on the Cobb angle increase. This brace effect, however, could not be seen for the progression rate of the lateral deviation and axial rotation. These results are in agreement with recent studies concerning the three dimensional analysis of the shortterm effects of the Boston brace system6.

D.J Wc\:er el al. / Curve Progression and Spinal Growth

asm.75m.2S0i.Mi

Fig l

The median, 95th, 75th, 25th and 5th percentiles of the spinal growth velocity at consecutive chronologic ages of the patients. The different percentiles of the growth velocity were fitted with a third grade polynomial (r2 = 0.93). ~l

Remaning '» Grow* T1-14

(mm)

too

I

t

10 11 12 11 14 is

ie

u

Chronologic*

Fig 2

The median, 95th, 75th, 25th and 5th percentiles of the remaining spinal growth at consecutive chronological ages of the patients. The different percentiles of the growth velocity were fitted with a third grade polynomial (r2 = 0.99).

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Growth charts were derived from the measured individual growth velocity values of the patients of the study. At the age of 10 years an average length increase of 10 cm of the T1-L4 segment is expected, which varies from 4.5 cm to 17 cm. This variation in growth speed per individual may be an explanation for the variation of expression of idiopathic scoliosis. After the age of 16.5 years the growth speed barely exceeds 10 mm per year, the growth speed under which only small progression should be expected on the basis of the data of the current study. In conclusion, it is clear that the length of the spine measured on subsequent radiographs is an excellent parameter to determine spinal growth and therefore an excellent predictor of scoliosis progression. The current advance of digital radiographs makes it possible to easily quantify various geometric variables of the scoliotic curve. In addition to the various three dimensional parameters, the length of spine is an important variable for the clinician to determine the growth of the patient with scoliosis.

References 1. 2.

3. 4. 5. 6.

Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg 66 A:106\-\Q71, 1984. Peterson LE, Nachemson AL: Prediction of progression of the curve in girls who have adolescent idiopathic scoliosis of moderate severity. Logistic regression analysis based on data from The Brace Study of the Scoliosis Research Society. J Bone Joint Surg 77A:823-827, 1995. Lonstein JE, Winter RB: The Milwaukee brace for the treatment of adolescent idiopathic scoliosis. A review of one thousand and twenty patients. J Bone Joint Surg 76:1207-1221,1994. Ylikoski M: Spinal growth and progression of adolescent idiopathic scoliosis. Eur Spine J 1:236-239, 1993. Stokes LAP, Bigalow LC, Moreland MS: Measurement of axial rotation of vertebrae in scoliosis. Spine 11:213-218,1986. Aubin CE, Dansereau J, de Guise JA, Labelle H: Rib cage-spine coupling patterns involved in brace treatment of adolescent idiopathic scoliosis. Spine 22:629-635, 1997.

Table 1

The mean progression rate of the thoracic curve of all patients, in the period before brace treatment, and during brace treatment, in the three growth phases.

Growth rate < 1 o mm/year

Progress! on rate

Growth rate >10, <20 mm/year

Mean

SEM

n

Mean

SEM

5.4

0.92

0.7**

0.6

36

3.2*

1.00

0.3**

084

35

01**

048

28

n

Growth rate > 20 mm/year Mean

SEM

n

8

6.8

1.34

12

33

3.3*

1.40

12

Cobb angle increase (degrees/year) No Brace Brace Lateral deviation increase (mm/year) No Brace Brace

4.6

1.41

8

5.7

1.48

12

4.0

0.94

33

5.1

2.17

12

3.6

0.98

8

4.4

1.31

12

3.3

0.67

25

4.1

2.07

10

Axial rotation increase (degrees/year) No Brace Brace SEM

standard error of the mean

*

Significant different from no brace group (Mann-Whitney U test; p < 0.05)

**

Significant different from other growth velocity groups (Kruskal Walls H test; p < 0.05)

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Personalized Biomechanical Modeling of Boston Brace Treatment in Idiopathic Scoliosis D. Perie D., C.E. Aubin Ph.D., M. Lacroix B.Eng., Y. Lafon B.Eng., J. Dansereau Ph.D., H. Labelle H. M.D. 1 - Canada Research Chair "CAD Innovations in Orthopedic Engineering ", Ecole Polytechnique, PO Box 6079, Downton St., Montreal (Quebec) Canada H3C 3A7 2 - Research Center, Sainte-Justine Mother-Child University Hospital, 3175 Cote-Sainte-Catherine Rd, Montreal (Quebec) Canada H3T1C5 Abstract. The aim of this study was to describe how the Boston brace modify the scoliotic curvatures using a finite element (FE) model and experimental measurements. The experimental protocol, applied on 12 scoliotic girls, was composed of the pressure measurement at the brace-torso interface followed by two radiographic acquisitions of the patient's torso with and without brace. A 3D FE model of the trunk was built for each unbraced patient. The brace treatment was represented by two different modeling approaches: 1) using equivalent forces calculated from the measured pressures; 2) by an explicit personalized FE model of the brace (hexahedral elements) and its interface with the torso (contact elements). In the first model, measured brace forces less than 40N and up to 113N induced respectively less than 21% and up to 87% of real correction. Thoracic forces induced the main correction, affecting partially both lumbar and thoracic curves, in agreement with the literature. In the second model, the brace closing reduced the curves up to 35% of real correction. Contact reaction forces (16-79N) were similar to real brace forces (11-72N). The results suggested that other mechanisms than brace pads contribute to the equilibrium of the patients. Postural control by the muscular system remains a problem to address in a future study. The second model represented more realistically the load transfer from the brace to the spine than external forces application. With such model, it is expected to predict the effect of a brace before its design and manufacturing, and also to improve its design.

1. Introduction and objectives In the literature few biomechanical studies were conducted to assess brace effectiveness in the treatment of idiopathic scoliosis. Strap tensions and pad pressure were measured within the Boston and Milwaukee braces. But the way these loads modify the 3D spine curvatures was not clearly described. Biomechanical models were developed to simulate and analyze brace biomechanics [1, 2, 3, 4, 5]. External forces representing brace pads were applied to specific scoliotic patient's geometry. This way of modeling is not truly realistic since brace loads are in fact reaction forces and are depending on the relative flexibility and geometry of the brace and trunk. Also, the complex mechanical action of the brace on the entire torso was not completely addressed. The aim of this study was to describe how the Boston brace modify the scoliotic curvatures using a finite element (FE) model and experimental measurements. Two different approaches of the brace treatment modeling were proposed and compared.

3^4

/). Peru1 ct til. / Pci'soiHiti-t'el Hioniecluintcal Modeling of Boston Brace Ii'ciitnirnt

2. Materials and Methods Eleven girls (13-14 years old) were recruited from the scoliosis clinic at Sainte-Justine Hospital on a volunteer basis. The subjects were having progressive adolescent idiopathic scoliosis. The average spine deformity was measured at 36/E±7JE and 27vfi±8/t of Cobb angle respectively for the thoracic and lumbar segments, with apical vertebrae in T7-T12 and L1-L4. They were all treated by a Boston brace system. Two radiographic acquisitions of the patient's torso geometry (standard posteroanterior (PA), PA with a 2(h€ angle down pitch, and lateral) were done, the first one without the brace and the second wearing the brace (Fig. 1-a). It was followed by the measurement of the pressure at the brace-toYso interface (Fig. 1-b). The entire protocol was performed at the brace delivery within the same hour, and was approved by the hospital

ethic committee. A FE model of the trunk [2, 6, 7] was built for each patient without brace (Fig. 2a). The thoracic and lumbar vertebrae, intervertebral discs, ribs, sternum and cartilages were represented by 3D elastic beam elements. A detailed modeling of costo-vertebral, costotransverse and zygapophyseal joints was developed using point-to-surface contact, shell and multilinear elements. The vertebral and intercostal ligaments were represented by 3D elastic spring elements. The mechanical properties were taken from experimental data [7J. The brace treatment was represented by two different modeling approaches: 1) using equivalent forces calculated from the measured pressures (Fig. 2-a); 2) by an explicit personalized FE model of the brace (hexahedral elements) and its interface with the torso (contact elements) (Fig. 2-b). The first brace treatment modeling was simulated in 3 successive load steps. The first one consisted in applying the lumbar forces, then in adding the thoracic forces and finally in applying the real in-brace displacement of Tl (which approximated the patient's righting reflex). The second brace treatment modeling was simulated in 3 successive (different) load steps: 1) the brace opening, 2) the brace translation onto the trunk (to include the patient's trunk); and 3) the brace closing. In both approaches, the lowest available vertebra or the pelvis was fixed. The deformed geometry of the patient's trunk was computed at each load step and compared to the real in-brace geometry by means of several computed geometric

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parameters. The reaction forces in contact elements were compared to equivalent forces calculated from the measured pressures. 3. Results Two Boston brace force patterns were identified. The first one consisted in high right thoracic forces of 56-113N and lumbar forces less than 47N. The second one consisted in low thoracic forces less than 20N and lumbar forces up to 70N. Using the first model (Fig. 3-a), these passive forces produced up to 9JE of Cobb angle correction and up to 20mm of vertebral displacements. Brace forces less than 40N entailed less than 21% of real correction. Brace forces up to 113N entailed up to 87% of real correction.

•40

-20

20

40

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I). Pcrw et cil. / Pcrson(ili:c(l Hiomecluinical Modeling t>t Koston Brace Treatment

Contact reaction forces of 16-79N were obtained form the second model, while measured forces were in the range 11-72N. The closed contact nodes of the model were located near the application node of the measured force (standard deviation of 6 cm). The brace closing reduced the spinal curvatures up to 35% of real correction.

4. Discussion The results of the first brace treatment model showed that high thoracic pads reduced more effectively both thoracic and lumbar scoliotic curves than lumbar pads. The response of this model to the application of the passive external forces should be interpreted with caution because of the boundary conditions (zero displacement applied to L5 and Tl). Also, the lumbar forces were applied directly on the spine while the effective loads could be different from pressure measurements. The second biomechanical model of the trunk used in this study is considered as an improvement over previous biomechanical models developed for orthotic treatment simulations because of the explicit patient-specific representation of the brace. This way of modeling is more appropriate that the traditional application of external loads because brace loads are in fact reaction forces and are depending on the relative flexibility and geometry of the brace and trunk.. This study showed the feasibility and the interest of such novel approach to analyze brace biomechanics. This model represents more realistically the load transfer from the brace to the spine than the external forces application. For both brace treatment models, the results suggested that other mechanisms than brace pads produce correction and contribute to the force equilibrium within the brace. Postural control by the muscular system remains a problem in this study. This phenomenon is difficult to quantify. An active representation of the muscles in the model should improve the simulations.

References 1. 2. 3. 4. 5. 6. 7.

Andriacchi et al. (1976) Milwaukee brace correction of idiopathic scoliosis. J. Bone and Joint Surg. 58A(6): 806-815. Aubin et al. (2002), Personalized Biomechanical Simulations of Orthotic Treatment in Idiopathic Scoliosis. J. Orthop. Research, in revision. Gignac et al. (2000), Optimization method for 3D bracing correction of scoliosis using a finite element model. Eur. Spine J. 9:185-190. Parwardan et al. (1986), A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis. J. Biomech. 19-2: 103-117. Wynarsky et ai. (1991) Optimization of skeletal configuration: studies of scoliosis correction biomechanics. J. Biomech. 24-8, 721-732. Aubin C.E. et al. (1995) Geometrical modeling of the spine and thorax for biomechanical analysis of scoliotic deformities using finite element method (in French). Ann. Chir. 49(8), 749-761. Descrimes J.L., Aubin C.E. et al.,, (1995): Introduction des facettes articulaires dans une modelisation par dements finis de la colonne vertebrale et du thorax scoliotique: aspects mecaniques, Rachis, 7:5, 301-314.

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Intelligent Brace System for the Treatment of Scoliosis E. Lou1, D. Benfield1, J. Raso1, D. Hill1, N. Durdle2 'Capital Health Authority, Glenrose Site, 10230-111 Ave Edmonton AB, Canada T5G OB7 2 University of Alberta, Edmonton, AB, Canada T6G 2G7 email: [email protected]

Abstract Measurement of the biomechanical effectiveness of a brace for the treatment of scoliosis has been hampered by the lack of compressive information about wear characteristics. Orthotists and orthopaedic surgeons believe that the effectiveness of bracing is correlated with the strap tensions. If the strap tensions can be maintained at the optimal level while patients wear their braces, a better treatment outcome may be obtained. However, strap tensions vary significantly during different activities. An intelligent brace system has been developed to control the strap tension so that the optimal prescribed level is maintained at all time. This system consists of an innovative strap tension transducer, a microcomputer unit and a motorized unit. The strap transducer has been developed with an accuracy ±1.0N in the range of 0 to 100N. An instrumented Boston brace was built to test the concept. When the strap tension was below 80% of the prescribed level for a 15 minutes interval, the microcomputer unit signaled the motor to tighten the strap. While the strap tension level was above 120% of the prescribed level for a IS minutes interval, the motor reversed the direction. Laboratory testing results showed that the strap tension could be maintained at the optimal prescribed level.

1. Introduction Scoliosis is an abnormal curvature of the spine with vertebral rotation. Brace treatment is the most commonly used in non-surgical treatment for patients who have potentially progressive spinal deformity. The primary purpose of brace treatment is to prevent further increase of spinal curvature. However, the effectiveness of bracing is uncertain [1,2]. The amount of support and corrective action provided by a brace depends on the location, magnitude and direction of the pressures exerted upon the spine [3]. Successful brace treatment is thought to require patients to wear braces as prescribed, including securing the straps to provide a level of pressure on the convexity of the curve. Opinion concerning the effectiveness of braces turns on two points: do patients wear the brace as prescribed and is the correction due to mechanical support. By examining in-brace curvatures, Willner [4] showed that lateral forces are more important than elongation forces to the correction of spinal deformities. Jiang et al [5] measured the magnitude, location and direction of pressure generated by the brace as well as the forces in the straps, and found that there was considerable variation in how braces are worn by patients. Some children secured the brace very aggressively and imposed high loads on their trunks; other children, who wore the brace loosely, imposed little pressures. Wong et al [6] found that the standing Cobb angle correlated with the pressure pad and the

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strap tension. If the strap tension of the brace can be adjusted automatically and maintained at the prescribed level, optimal treatment outcome may be obtained. 2. Objective The purpose of this study was to determine whether the strap tension was able to be controlled by a microcomputer system to maintain the strap tension at the optimal prescribed level. 3. Methods and Materials The intelligent brace system consists of a strap tension transducer, a microcomputer unit and a mechanical motor system (Figure 1). The strap tension transducer will be mounted at the top buckle position to measure the strap tension. The microcomputer unit will be carried while a subject wears her brace. The motor system is used to control the tightness of the strap tension. 3.1 The Strap Tension Transducer The instrumented strap tension transducer was built by the authors. The constraints were that it was small, consumed low power, sensitive over the load range, non-obtrusive and cost effective. The transducer consisted of an aluminum ring in the center with two brass rectangular loops at each end (Figure 2). Four strain gauges were mounted on the aluminum ring (2 on the outer surface and 2 on the inner surface) and formed a wheatstone bridge circuitry. Each pair of strain gauges provided temperature compensation and greater the sensitivity. The electronics with amplifier were mounted close to the transducer so that electronic noise picked up from the strain gauge fine wires to the amplifier was minimized. The voltage from the transducer was linearly proportional to the applied tension. ^ Motorized system J Microcomputer Unit Strap tension transducer

Figure 1. Block diagram of the brace system.

Figure 2. An instrumented strap tension transducer.

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3.2 The microcomputer unit The microcomputer unit consisted of a microcontroller and memory with associated circuitry, battery recharging circuit and rechargeable battery. The unit was packaged in a box with dimensions 55mm x 80mm x 20mm and its weight was only 60g. The system was easily to carry and hide under clothes. This unit has been used for measuring forces and compliance during daily activity [7]. Only the software was modified to control the motor. Patients use a belt clip or velco to carry the system while they wear their braces. The system requires recharging everyday for a maximum 2 hours. Data stored in memory can be downloaded for further analysis. 3.3 The motorized system The mechanical motor system consisted of a motor with a gearmotor mechanic. The selection of motor was very challenging. The motor was required to be small and consume low power, but at the same time it had to provide enough torque to adjust and hold the strap. Also, a safety release was necessary in case of the malfunction of the motor. If the strap tension was below 80% of the prescribed level for a 15 minute interval, the microcomputer unit caused the motor to tighten the strap tension level. When the strap tension level was above 120% of the prescribed level for a 15 minute interval, the motor reversed the direction. The motor with its gear mechanism can hold loading up to SON. The frequency of strap adjustment is software controllable and is a trade-off between power consumption, subject intrusiveness and effectiveness. When adjusting the strap tension, the motor was loosened or tightened a fixed amount. It is necessary to prevent the motor from tightening the strap too much. Excessive loosening although causing the brace to be less effective does not cause a safety risk. Having the brace too tight could impose excessive loads upon the body and also damage the mechanism. The limiting of the active motor was controlled by software. 4. Laboratory Experiments and Results An instrumented Boston brace (Figure 3) was developed to test the concept of controlling strap tension by using the microcomputer system. The strap tension transducer was calibrated by hanging weights on one side and fixing the other end. Three trials of loading and unloading experiments were performed. Calibration (Figure 4) showed that the system could calculate the forces accurately to within ±1N with resolution ±0.5N. 4 3.532.5-

21.510.50

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40

60

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Figure 3. Instrumented Boston Brace.

Figure 4. Calibration Results.

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£. Lou et (il. /Intelligent Hrace S\stem for the Treatment of Scoliosi.\

The instrumented Boston brace was tested after the buckle transducer was calibrated. An air bladder was put inside the brace and inflated to known pressure levels using a standard blood pressure measurement gauge. In practice, an orthotist will set the prescribed tightness of the brace. The microcomputer will "learn" and record the corresponding strap tension. In this test, the prescribed level was set at 18N. The trigger points were set at 80% and 120% of the target level. Tightening occurred when the pressure was below 80% of the target (14N) for 15 minutes (30 consecutive samples at 1 sample per 30 seconds). Loosening occurred when the pressure was above 120% of the target (22N) for 15 minutes. During tightening or loosening the sample rate was increased to 1 sample per 10 seconds. The air bladder was inflated and deflated to level below and above the trigger points to verify correct operation of the unit. 5. Conclusions and Future work A prototype intelligent brace had been developed to prove that the strap tension was able to be controlled and maintained at the optimal prescribed level. However, the actual design of the motorized system still requires improvement. A safe mechanism and a motor with higher loading specifications are required. Clinical trials will be conducted in future. References 1. 2. 3. 4. 5. 6. 7

M. A. Asher and W. H. Whitney, Orthotics for Spinal Deformity, Orthotics Etcetera, Baltimore, 1986. R. G. Houghton et al., Monitoring True Brace Compliance. Proceedings of the 21st. Meeting of the Scoliosis Research Society, Hamilton, 21-25 September 1986, 101. G. T. Wynarsky, A. B. Schultz, Trunk Muscle Activities in Braced Scoliosis Patients. Spine 14 (1989), 1283-1286. S. Willner, The effect of the Boston brace on the frontal and sagittal curves of the spine. Ada Orthop Scand, 55 (1984), 457-460. H. Jiang et al., Interface Pressures in the Boston Brace Treatment for Scoliosis. Proceedings Int'l Symposium on 3-D Scoliotic Deformities, Montreal, 27-30 June 1992,395-399. M. S. Wong et at., Effectiveness and biomechanics of spinal orthoses in the treatment of adolescent idiopathic scoliosis (AIS).' Prosthetics & Orthotics International, 24, (2000), 148-162. E. Lou et al., The Daily Force Pattern of Spinal Orthoses in subject with Adolescent Idiopathic Scoliosis. Prosthetics and Orthotics International, 26, (2002) 59-63.

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Spine-Straight Device for the Treatment of Kyphosis E. Lou1, J. Raso1, D. Hill1, N.Durdle2, M.Moreau2 'Capital Health Authority, Glenrose Site, 10230-111 Ave Edmonton AB, Canada T5G OBJ 2 University ofrfAlberta, Alberta, Edmonton, Edmonton, AB, Canada Cane T6G 2G7 email: edmond [email protected]

Abstract Kyphosis is an excessive rounding of the upper spine. Its treatment depends upon the severity, the age of the patient and the levels of the spine that are affected. Early diagnosis is a key to providing optimal treatment. In a skeletally immature patient, an exercise program or bracing is the most commonly used treatment. However, the compliance of bracing for adolescents is poor and exercise training is labor intensive. The purpose of this study is to determine whether a Spine-Straight device can help patients to correct their kyphosis themselves and there by reduce back pain without the biomechanical support of a brace. The Spine-Straight device consists of an accelerometer and a microcomputer unit. The accelerometer is used to measure the kyphotic angle and the microcomputer unit controls a pager vibrator to alert patients when their posture exceeds personalized thresholds. The system was tested in the laboratory before used by subjects. The results were compared to back data obtained from a laser scanner imaging system. The maximum angle deviation between the laser scanner and the Spine-Straight device was 1.5 degrees. Two volunteers tested the systems for 2 days. The accelerometer was placed at the T3 location and the microcomputer unit was carried during daily activities. The angle measurement was recorded at 1 minute intervals during daily activity over a period of 2 days. The preliminary trials demonstrate subjects can improve their posture when feedback signals were provided.

1. Introduction Kyphosis is defined as standing in a hunched over posture with shoulders drooped forward. Kyphosis results from a variety of causes. The most common cause for kyphosis is purely postural. Children stand in a hunched over position for a variety of non-physical reasons: it is easier, they may be lazy, they may have low self-esteem, or, in adolescent girls, they may slouch to hide developing breasts [1]. Poor posture usually worsens during the adolescent growth spurt, when a child may assume a more pronounced round back. Poor posture of this form, in which no underlying deformity or disease exists, is known as postural round back and usually is a correctable situation. The diagnosis of postural round back can be made in two ways. First, determination of the flexibility of the spine - during examination the roundness corrects with hyperextension (bending backwards) or improvement of posture by the patient. When the child bends forward, a smooth gentle curve is seen, as opposed to a sharp peak as seen in Scheuermann's disease. The second way to diagnose postural round back is by exclusion ruling out other causes through radiographs. The standard treatment for postural round back is education regarding proper sitting and standing. For children who continue to stand in a slouched position, an exercise program is the second line of treatment. Exercises can strengthen the scapular muscles and spine extensor muscles. Typically, a physical therapist teaches an exercise regimen to the child and

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sets up a program for the patient to do at home. The therapist is required to periodically meet with the child, to assure that the exercises continue to be done properly. The sooner physical therapy is started, the less likely the child will end up with a humpback deformity. Everyone has kyphosis to some extent, and curves as seen on radiographs of 20 to 40 degrees are considered normal. For curves over 40 degrees, an exercise program is beneficial. Surgery will not generally be performed unless the curve goes beyond 75 degrees. If exercises are not effective in reducing the kyphosis, then a brace may be used. Bracing can be effective for kyphosis in the growing child if patients are compliant. However, the exercise program is labor intensive and the compliance for bracing is poor. An un-obtrusive selfteaching device has been developed to provide an alternative treatment for kyphosis.

2. Objective The purpose of this study was to determine whether a Spine-Straight device could detect the postural changes during daily activities and help patients to correct their kyphosis. 3. Constraints 1. Spine-Straight device compliance must be higher than brace compliance. 1. Spine-Straight device reduces the overhead cost. 1. Subjects must be able to improve their kyphosis when feedback is given.

4. Methods and Materials An accelerometer, 1 .Ocm x 1 .Ocm x 0.6cm, was attached to the back of the patient at around T3 location (Figure 1). This accelerometer was selected because of the low power consumption, small size and high accuracy. The resolution of the accelerometer was 1.5 degrees over a full range (0 - 90 degrees). The microcomputer unit consists of a microcontroller, memory with associated circuitry and a battery pack. The whole unit was packaged into a box (Figure 2) with dimensions of 5.5cm x 8.0cm x 2cm and its weight was approximately 25g. Subjects carried the system with a belt clip during this study. The system requires recharging everyday for a maximum 2 hours. 0 is the angle measured from the accelerometer.

Figure 1. Sagital view of the accelerometer location.

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Figure 2. The microcomputer unit.

In laboratory testing, measurements were taken at 2 samples per second for 10 seconds in each of four postures (standing, forward and backward bending, and repeated standing). The repeated standing was used to detect any movement of the accelerometer after activites. Digital images were captured at each of the positions (Figure 3). To test the accuracy of the Spine-Straight device, an image with a laser scanner (Minolta 700) was taken with the accelerometer in place. Software written in MATLAB was used to calculate the kyphosis. Two volunteers used the system for 2 days trial during their normal daily activities. On the first day, no feedback was provided. Feedback was provided on the second day while the measured angle was more than the personalized threshold value. Feedback was in the form of buzzer (similar to a pager) emitting a vibration for two seconds. For this study, the threshold was set 5° higher than normal standing. The sample rate was set at one sample per minute. The sampling rate was adjustable under software control and was set at a level that was not too frequent as to cause annoyance but often enough to make the subjects aware of their posture. Both subjects used the system more than 6 hours per day. 5. Results The accuracy as measured during calibration in a laboratory setting of the laser scanner system and the accelerometer for the angle measurement were ±1° and ±1.5°, respectively. In laboratory measurements, the angles measured from the accelerometer on subject 2 at the three postures, standing, bend forward and bend backward, were 15±0.7°, 52±0.5° and 5±0.7°, respectively. The repeated standing measurement was 15±0.4°. The

Figure 3. The back images of the three postures.

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E. Lou et nl. /Spine-Straight Device for the Treatment of K\pho\is

angles from the laser scanner system at the same postures were 15.5°, 53.5° and 5°, respectively. The maximum angle deviation between the laser scanner system and the SpineStaight device was 1.5 degrees. On the 2 day trial, the average angle 0 on day 1 and day 2 during normal daily activities were 63116° and 72±15° for subject 1, and 68±21° and 76±14° for subject 2. Both subjects used the system while they did their routine work during the day. No specific activities or movements were recommended. Subjects were asked to respond to the feedback on the second day. Figure 4 (a) and (b) shows the frequency distribution of the angle measurements of subjects 1 and 2, respectively.

6. Discussion and Conclusions For the 2 day trial, subject 1 reported that he was standing more often than sitting during both days; however, subject 2 was sitting more often than standing. Also, they both reported that they tried to respond to the feedback as many as possible. The change of the angle 9 was more significant on subject 1 than subject 2. This might be due to the subject 1 has a bigger kyphotic angle than subject 2. Both subjects commented that the system was light, easy to carry and un-obtrusive. From both results, we found that the average value of angle 9 was smaller on the second day than on the first day. This might be due to both subjects straightening their spines more often. This preliminary study illustrated that the system was able to detect the change of subjects' postures, and may help subjects to improve their postures if they respond to the feedback. Reference Detroit Medical Center: Definition of Kyphosis. [Patient Information web site]. Available at http://www.dmc.org/health info/topics/bone3433.html Accessed since 1998.

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Study of vertebral morphology in Scheuermann's kyphosis before and after treatment E. Pola, S. Lupparelli*, A.G. Aulisa, G. Mastantuoni, O. Mazza, V. De Santis Clin. Orthop. Pol. A. Gemelli - Universit_ Cattolica del Sacro Cuore, Roma, ITALY * Centra Orthopedico Umbro, Perugia, ITALY Abstract Variation of vertebral morphology in Scheuermann's Kyphosis before and after orthopedic treatment is usually measured by the entity of the curve, using Cobb's method, and by vertebral wedging. But the lack of correlation between these parameters and the clinical evolution of the deformity , lead to the possibility of other alterations that can explain part of the kyphosis deformities before and after the treatment. In this group of alterations the inclination of anterior and posterior walls, that express the trapezoid deformity of vertebras, seem to be more reliable indicators of curve response to ortopedic treatment.

1. Introduction In 1920 Scheuermann [1] first described the association of developmental Kyphosis and wedging of thoracic vertebrae; he used the term "osteochondritis juvenilis dorsi" [2], but the condition is universally known today as Sheuermann's kyphosis. Sorenson [3], proposed a diagnosis based on the presence of three or more adjacent vertebrae wedged 5° or more and no evidence of congenital, infectious or traumatic disorders of the spine. These criteria are widely accepted and used today. Vertebral geometry alterations in Scheuermann's kyphosis and results of the orthopedic treatment have been measured by radiographic measure of both curve entity and vertebral wedging on longitudinal section [4,5,6,7,8]. Clinical evolution of the deformity is not always correlated to presently used radiographic parameters. On the other hand, it is possible that vertebal morphology alteration in kyphotic curve could be explained by a more complex theory model than the currently accepted one. In this case currently used radiographic parameters could be insufficient for the evaluation of entity, progression and response to medical treatment. We have made a revision of our cases in order to define present parameters limits and, at the same time, to determine new parameters, which could be useful for a better correlation between clinical and radiographical findings and a better description of vertebral alterations. 2. Materials and Methods We made a retrospective study on a specimen of 16 patients with Scheuermann's kyphosis, treated using anti-gravity brace between 1996 and 2000, at Agostino Gemelli Hospital, department of Orthopaedics, Rome, Italy. 90% of our patients is male, 10% female.

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E. Pola a til. / Sn«l\ nf Vcrrchral Mt>rplitilt>i>\ in Sclicueriiuinn's K\plutsis

The mean age at the beginning of the treatment was 13 years. All patients had the same bone maturity grade, determined by Bick's method [9,10]. The mean curve entity before treatment , measured by Cobb's method, was 54,5°, a value that, according to literature data, requires orthopaedic treatment [11]. Radiographical measurement were performed on radiographs taken from a focal distance of 2 meters, on radiographic film 36x91 cm, from a lateral projection, at the beginning and at the end of the treatment. Vertebral geometry modifications before and after treatment were analysed according to the following parameters, evaluated by three independent researchers: - Anterior wedging angle (ALFA) Anterior wall inclination (AANT) - Posterior wall inclination (APOS) Anterior wedging angle ALFA has been calculated by two methods (figure la and Ib). The first method, used in the measurement of small deformities, is the calculation of the convex angle obtained by the intersection of two lines, orthogonal to both of the two lines passing through the extremities of superior and inferior vertebral body limits. The second method, used in the measurement of severe deformities, is the calculation of the convex angle formed by both of the two lines passing through the vertebral plates. The degree of inclination of the anterior wall (AANT) and posterior wall APOS has been measured by the disk limit of every vertebral body (figure 2). Specifically, we measured the angles formed by the line orthogonal to the inferior plate and the line passing trough inferior and superior limits of the anterior and posterior wall. Study of the variation of these three parameters (ALFA, AANT, APOS) before and after orthopaedic treatment was conducted in two phases. During first phase modification of both parameters was analysed with the confrontation of pre- and post-treatment vertebral values, not considering the vertebra position in the kyphotic curve. During the second phase we analysed data dividing vertebras in sub-groups, or sectors, in relationship to their position in the curve. Inclusion of the vertebras in a defined sector followed these criteria: apex vertebra received, conventionally, value 4; upper vertebra received value 3, and lower vertebra value 5. Vertebras positioned at highest and lowest limits of the kyphotic curve received, respectively, value 2 and 6. We took L2 as control vertebra, and gave it value 1. 3. Statistics Measurement variability among observers has been analysed by the Bland-Altman test. The absence of a significant variability among measurements performed by three independent observers enabled us to use, in the statistic elaboration, the mean value of three measurements, taking into consideration every parameter. We used the Shapiro-Wilk test in the evaluation of the gaussian distribution of the pre-treatment ALFA, AANT and APOS values. This evaluation was necessary, as we were analysing a specimen not selected from general population through a random process, and because it could not satisfy central limit teorema. Test signification (P<0.05), showing normal distribution of parameters values, allowed us to use, in the statistical interference procedure, the t-test for paired data, i.e. a parametric test, appropriate when the data show normal distribution. Significative level has been fixed at P<0.05. 4. Results The results of the analysis are shown in tables !-6.

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Figure la and Ib Method for anterior wedging angle ALFA measure Top (figure la) method used for the measure of mild deformity: calculation of convex angle formed by two lines perpendicular to the lines passing through posterior and anterior limit, respectively of superior and inferior disk plates of vertebral body. Bottom (figure Ib) method used for the measure of severe deformity, calculation of the convex angle formed by two lines passing trough vertebral plates.

Figure 2 Measure of anterior wall inclination AANT and posterior wall inclination APOS , conducted using disk plate limits of every vertebra. More specifically, we have calculate the angles between the line perpendicular to inferior plate and the line passing trough superior and inferior limit of anterior and posterior wall, respectively.

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Table I shows data without making sector division, while tables II-VI show results with the vertebrae divided in sectors. Whole iperkyphotic curve. The pre- and post-treatment variation in ALFA, AANT and APOS parameters in all the kyphotic curve vertebrae shows a significant reduction in the wedging angle ALFA (P<0.01) and in the posterior wall inclination APOS (P<0.0002). There was no significant variation in the anterior wall inclination. Sector 2 . In this sector, before treatment, mean wedging was 5° Cobb, the posterior wall ventral inclination was 4° Cobb and the anterior wall dorsal inclination was 2° Cobb. After treatment the wedging decreased from 5° to 3° (P not significant), the anterior wall inclination did not show significant variation, and the posterior wall inclination decreased by about 50% in value (P<0.02). Sector 3 . In sector 3 we saw an increase, after treatment, of the wedging angle and the anterior wall inclination values. The posterior wall inclination decreased. Value variation, however, was not significant. Sector 4. At the apex vertebra level, body wedging, which is the highest among the vertebral wedging in all sectors, decreased by 50% in value after treatment (P<0.004). The anterior and posterior wall inclination decreased, even if the value variation was not significative. Sector 5. Wedging angle showed an increase, even if not significant, of about one grade, while the anterior wall inclination showed no significant variation. The posterior wall inclination decreased (PO.009). Sector 6. In sector 6 the wedging angle decrease was not significant and the increase in the anterior wall inclination was not significant, either. The posterior wall inclination recorded a significant decrease of about 2°(P<0.001). 5. Discussion Conservative treatment of vertebral deformity promotes the application, via appropriate geometry orthesis, of external forces to obtain, during skeletral growing, remodelling of the deformed vertebras. In the case of the specific treatment of Scheuermann kyphosis using an antigravity brace, the biomechanical action of the brace applies external forces related to the three points principle: one force is applied behind the curve apex and the other two forces are applied at the end of the vertebrae at the curve ends. Moreover, in according to the vector calculation principles, a force applied to a curve structure is divided in two components with direction and course determined by the application point and by the space orientation of the resultant. Therefore it is logical that forces applied by an antigravity brace could produce different effects on the vertebral remodelling, depending on vertebra position. Moreover, it's highly probable that vertebral body deformation caused by an alteration of biomechanical properties of the movement segment, due to the alteration of ossification nuclei in vertebral bodies, [12,13,6], consist of a complex variation of vertebral geometry. Therefore, the deformation of movement segments, as a consequence of the orthesis treatment action, could not be adequately evaluated with present parameters, such as the wedging angle and the curve entity. The results of our research seem to confirm both theses. Data analysis shows that spine remodelling in Sheuermann kyphosis is the resultant of two components: vertebral wedging, represented by the anterior wedging angle ALFA, and trapezoid deformation, shown by the anterior wall inclination angle AANT and the posterior wall inclination angle APOS. Before the treatment wedging was present in all vertebrae including the curve range, and it was most apparent in the apex vertebra and very high in the adjacent vertebrae, with a

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certain prevalence in the superior vertebra. After the treatment the wedging evolved differently in relation with the position of the studied vertebra. The restoration was very good in apex vertebra, good in sector 2 vertebrae and average in sector 6 vertebrae. It was zero in the vertebra inferior to apex, while deformation was even worse in the superior vertebra. As for the trapezoid deformity, at the beginning of the treatment this was most apparent in the vertebra superior to apex, very high in apex vertebra and rather high in the superior end of the curve, while it was not so evident in the inferior end. At the end of the treatment the variation in the inclination of both the anterior and the posterior wall shows, despite the variability of results, constant improvement, more evident in the distal sectors than in the apex vertebra. So our study data shows that, in a state-of-the-art corrective treatment of kyphosis, anterior vertebral wedging angle varied in a different way in the different spine sectors, and in some cases the wedging was even worse after treatment. The analysis of the variation of anterior and posterior wall inclination shows a constant improvement in the entire curve. Therefore it is probable that there are other alterations that could explain part of the kyphosis phenomena before and after treatment. We sustain that using new parameters to study vertebral remodelling enables us to reach a better comprehension of Sheuermann spine response to anti-gravity brace treatment. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Scheuermann HW: Kyphosis dorsal is juvenilis. Ugeskr Laeger 82:385-393, 1920 Scheuermann HW: Kyphosis juvenilis (Scheuermann Krankheit). Fortschr Geb Rontgenstr 53:1-16, 1936 Sorenson KH: Scheuermann's Juvenile Kyphosis. Cophenagen, Munksgaard, 1964 Ascani E, Montanaro A. Scheuermann's disease. In: Bradford D, Hensinger R (Eds): "The Pediatric Spine". Thieme Verlag, New York, 1985 Aufdermaur M. Juvenile kyphosis (Scheuermann's disease): radiography, histology and pathogenesis. ClinOrthop. 154, 166-174, 1981. Bradford DS, Moe JH. Scheuermann's juvenile kyphosis. A histologic study. Clin Orthop. 110, 45-53, 1975. Ferraro C, Fabris D, Ortolani M. Le deformita somatovertebrali nella malattia di Scheuermann. Studio radiologico e considerazioni biomeccaniche. Progress! in Patologia vertebrale. 5,23-37,1982. Fletcher GH. Anterior vertebral wedging. Frequency and significance. Am J Rheum. 57,232-238,1947. Bick EM, Copel JW. Longitudinal growth of the human vertebra: a contribution to human osteology. J Bone Joint Surg. 32-A, 803-814,1950 Bick EM, Copel JW. The ring apophysis of the human vertebra: contribution to human osteogeny. J Bone Joint Surg 33-A, 783-787, 1951 Aulisa L, Valassina A. La cifosi. In: Autori Vari "Argomenti di Ortopedia e Traumatologia, Verduci Editore, 1989. Ascani E, et al. Studio istologico, istochimico, ultrastrutturale. Progressi in Patologia Vertebrale. 5, 105109, 1982. Ippolito E, Ponseti IV. Juvenile kyphosis. Histological and histochemical studies. J Bone Joint Surg. 63A, 175-182,1981.

E. Pola et al. / Stnx\ in Schciicrmtinn 'v K\phn\i\

Table 1

ALFA AANT APOS

Avg ± DS pre-treat. 7,7115,79 2,22 ± 3,23 4,47 ± 4,23

Avg ± DS post-treat. 5,78 ± 5,02 2,1 7 ±2,77 2,74 ± 2,42

t-test

P

-2,44 -0,13 -3,86

0,01 0,89 0,0002

Table 1

Results of analysis on variations before and after anti-gravity brace treatment of: the anterior wedging angle (ALFA), the anterior wall inclination angle (AANT), the posterior wall inclination angle (APOS). It is evident that there gas an important reduction of wedging angle ALFA (P 0.01) and of the posterior wall inclination angle APOS (P<0.0002). Variation of the anterior wall inclination is not important. Confrontation with tables II-VI shows that statistic analysis on undifferentiated data is not able to study the effects of brace treatment on every single vertebra.

Table 2

ALFA AANT APOS

Avg ± DS pre-treat. 5,28 ± 4,87 1,91 ±2,14 4,06 ±3,78

Avg ± DS post-treat. 3,21 ±5,66 1.24 ±1,41 2,16±2,19

t-test

P

-1,34 -1,10 -2,36

0,17 0,27 0,02

Table 2 Results of analysis in sector 2 on variations of: the anterior wedging angle (ALFA), the anterior wall inclination angle (AANT) and the posterior wall inclination angle (APOS). In this sector, before treatment, the mean wedging angle is 5 ° Cobb, the posterior wall ventral inclination angle is 4° Cobb and the anterior wall dorsal inclination angle is about 2 °. After treatment the wedging angle decreases from 5 ° to 3 ° (P not significative), the anterior wall inclination does not record important variation, while the posterior wall inclination angle records a 50% decrease (P<0.02) Table 3

ALFA AANT APOS

Avg ± DS pre-treat. 7,88 ±5, 13 2,31 ±3,13 7,24 ± 5,24

Avg ± DS post-treat. 9,59 ±5, 12 3,01 ± 3,56 6,1 2 ±4,32

t-test

P

1,23 0,31 -0,67

0,28 0,69 0,51

Table 3 Results of analysis in sector 3 on variations of: anterior wedging angle (ALFA), anterior wall inclination angle (AANT) and posterior wall inclination angle (APOS). In this sector ,after treatment, wedging angle and anterior wall inclination angle increases. Posterior wall inclination angle decreases. Observed values variation isn't significative.

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Table 4 ALFA AANT APOS

Avg ± DS pre-treat. 15,32 ±6,12 3,84 ±2,75 6,34 ±3,71

Avg ± DS post-treat. 7,1 7 ±4,88 2,52 ± 3,29 4,23 + 3,12

t-test

P

-3,50 -1,52 -0,15

0,004 0,11 0,29

Table 4 Results of analysis in sector 4 on variations of: anterior wedging angle (ALFA), anterior wall inclination angle (AANT9 and posterior wall inclination angle (APOS). In apex vertebra wedging is higher than in all other vertebras in different sectors. Wedging angle decrease of 50% after treatment (P<0.004). Anterior wall inclination angle as well as posterior wall inclination angle decreases, even if the variation isn't important. Table 5 ALFA AANT APOS

Avg±DS pre-treat. 6,71 ±4, 11 2,21 ± 2,22 3,54 ±3, 10

Avg ± DS post-treat. 7,35 ±3,12 2,34 ±1,12 2,11 ±1,10

t-test

P

0,29 0,07 -3,09

0,77 0,93 0,009

Table 5 Results of analysis in sector 5 on variations of: anterior wedging angle (ALFA), anterior wall inclination angle (AANT) and posterior wall inclination angle (APOS). In this sector wedging angle increases, not significatively, of about 1°, while anterior wall inclination doesn't have important variations. Posterior wall inclination angle decreases significatively (P<0.009) Table 6

ALFA AANT APOS

Avg ± DS pre-treat. 6,07 ±4,25 1,20 ±0,09 3,22 ± 2,49

Avg ± DS post-treat. 4,67 ± 3,54 2,20 ±1,64 1,01 ±0,55

t-test

P

-1,23 0,95 -3,78

0,23 0,36 0,001

Table 6 Results of analysis in sector 6 on variations of: anterior wedging angle (ALFA), anterior wall inclination angle (AANT) and posterior wall inclination angle (APOS). In sector 6 wedging angle decreases not significatively and anterior wall inclination angle increases, as well not significatively. Posterior wall inclination angle decreases significatively of about 2M (P<0.001)

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Th.B.GrivasiEd.) Research into Spinal Deformities 4 IOS Press. 2002

Biomechanics of the conservative treatment in idiopathic scoliotic curves in surgical "Grey-Area" L. Aulisa, S. Lupparelli*, E. Pola, A.G. Aulisa, G. Mastantuoni, L. Pitta Clin. Orthop. Pol. A. Gemelli - Universit_ Cattolica del Sacro Cuore, Roma, ITALY * Centra Orthopedico Umbro, Perugia, ITALY

Abstract. The biomechanical behaviour of the spine significantly varies in relation to the age of the spine. Particularly, the elastic behaviour of the intervertebral discs has been proved to change during the spine growth, which changes the disc reaction to externally imparted forces. The biomechanical analysis of the G modulus of torsion rigidity of the intervertebral disc shows that the G values progressively increase through growth, which favours the progression of early scoliotic curves. At the same time, however, early structural scoliosis is more amenable to conservative treatment owing to the residual growth potential of the spine. Whereas indications to surgical treatment of scoliotic curves has been based upon the magnitude of the curves as measured according to the Cobb method, two additional factors affect the chance of correcting a scoliotic curve, The first is the residual growth potential of the vertebrae. In fact, a longer residual growth allows for external forces to be applied so as to change the growth model of the scoliotic spine, which ensures a stable correction of the deformity when these external forces are removed. The second is the magnitude of the elastic deformation of the intervertebral discs. It has been suggested that a deformation beyond the disc elastic behaviour, by producing hysteresis of the disc, renders the disc less susceptible to transferring the load to the neighbouring vertebral bodies, thus impairing remodelling. It ensues that both the age and the magnitude of rotation affects the success of conservative treatment and not only the magnitude in Cobb degrees. The curve localization adds to these two parameters, thoracic curves being stiffer than thoracolumbar and lumbar curves.

1.

Introduction

Evolution of spine deformities is determined not only by biological factors, but also by the mechanical behavior of abnormal system geometry. Previous biomechanical studies, analyzing scoliotic spine instability, allowed a partial biomechanical interpretation of scoliotic curves progression [1] [2] [3] [4]. These interpretations, according to clinical examinations, give us the material to set parameters and define limits of both orthopedic and surgical treatment. In this area, we want to extend our analysis to the determination of the elastic behavior of the scoliotic curves which are usually included in the surgical or orthopaedic "gray-area", considering their bend in Cobb grades. In particular our study aims to determine the mechanical and biological parameters, which go beyond the simple bend value expressed

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in Cobb grades, and which could be used as indicators of conservative treatment also in the cases that are usually included in the "gray area".

2. Mechanical Action of the orthesis The mechanical action of an orthesis for the conservative treatment of the scoliosis has two goals: - the stabilization of an unstable spine to transmit forces that, in a deformed spine, could restore the natural geometric configuration The stabilization is obtained by the reduction of the forces acting on the spine and by a redistribution of residual forces, and thereby avoiding their concentration in reduced areas. The different kind of orthesis used can obtain a good curve stabilization by reducing a great part of the forces acting on the spine and by limiting spine dynamics,. The restoration of the natural configuration is always obtained, despite the differences in methods, by applying traction, lateral deflection and derotation forces trough the sagittal, coronal and transverse planes of the spine. - The traction, obtained through the continuity of the skull-spine-pelvis system, is effective in severe scoliosis, while is less effective in mild curves correction. - The lateral deflection is obtained by pushes applied through appropriate lines and is effective in mild curves correction, while is not very effective in severe curves correction. White AA and Punjabi MM, in 1976, calculated that the effectiveness of traction and lateral deflection forces increases when the curve value in Cobb's grades is superior or inferior to 53° [5]. In the same study the Authors prove that the best correction is obtained by the combined use of traction and lateral deflection forces. The derotation is obtained by a posterior-anterior push on the gibbus with anterior chest push on the other side to produce a torsion couple . This produce a spine rotation trough the vertical axis, from the convexity side to the concavity side. The application of these forces depends on the right points of application, or vinculi. Without vinculi, the traction and the derotation and deflection pushes could not be applied to the spine. Moreover, forces effectiveness is determined by the type of anatomic structures interposed between application areas and spine. This means that: 1) The traction can be applied only if the spine is blocked at the two extremities, the inferior one being the pelvis and the superior one being the skull 2) The deflection can be obtained only applying the three points principle, i.e. the application of a lateral deflection push on the scoliotic segment necessitates an inferior application point in the pelvis and a superior application point in the area above the curve. Specifically, superior vinculus is: - the skull in cervical-thoracic and high thoracic curves - the superior ribs segments in the thoracic curves - the intermediate ribs segments in the thoracic-lumbar curves the inferior ribs segments in the lumbar curves The forces are transmitted by the thoracic cage and by the lumbar muscles.

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3) The derotation requires an inferior application point in the pelvis, to avoid the transmission of the torsion moment to the pelvic belt, and the application of a torsion couple: the pushes are applied to the gibbus, from the posterior to the anterior plane on the side of the convexity, and to the clavicula, the sternum and the ribs, from the anterior to the posterior plane on the side of the concavity. The analysis of the mechanical action of the orthesis shows, that the application of corrective forces supported by currently used braces presents limits that inevitably decrease their effectiveness [6] [7] [8] [9]. The first limit is represented by the relaxation phenomenon, that appears when a force is applied to a viscous-elastic structure like, the muscular-skeletal apparatus. "Relaxation" is the phenomenon observed when a force that causes a deformation is applied to a viscouselastic structure: the tension, faced with a constant deformation entity, decreases as time passes. This phenomenon means that the pushes would need to be reapplied almost everyday or that would be necessary to use braces which are able to adapt to the impact of their actions. The second limit is that the braces cannot transmit forces directly to the spine, but only through interposed organs and tissues. Their effectiveness is determined by the use of vinculi and pressure points, which do not always permit an effective transmission of the forces. More specifically, mechanical action is more effective when pushes are applied at the level of the thoracic cage, because the superior rigidity of this structure produce, unlike the abdominal cavity, a lesser dissipation of applied forces.

3.

Spine Biological response

It is impossible to explain the biomechanics of the orthopedic treatment of the scoliosis only from a mechanic point of view. Scoliotic spine response to the actions of the brace are determined, using the same treatment, by two factors: vertebrae remodelling capability ( in accordance with Huter-Volkman law) and the capability of the viscous-elastic structures to react to the imposed actions appropriately. Vertebrae remodelling is possible only during bone growth and remodelling capacity is linked to the residual growth percentage. No mechanical action can produce the remodelling process without an adequate response from the viscous-elastic structures involved. These structures, and in particular intervertebral disks, have the function of modifying the areas subject to tension concentration by adsorbing and by redistributing the actions of the brace on singular vertebrae. So the disks included in the scoliotic curve must act in the field of the linear elasticity. Disk istheresis could incapacitate the disk itself from transmitting effective actions to correct the deformity. As the intervertebral rotation and the torsion are the distinctive elements of a scoliotic curve, it is important the behavior of intervertebral disks during the torsion . Many studies show how this ability is a function of the G module of torsion rigidity of the disks [1] [2] [3] [4]. The G module of the disks presents great variations in relation to the rotation degree of the curve and with the initial phisiologic values of the disks involved.

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Experimental data define the elastic behavior of a disk model in an adult spine, in relation to the rotation angle produced by a torsion moment. A rotation angle of about 3° allows, after the ceasing of the torsion moment, a linear elastic return: an angle from 3 ° to about 12 ° produce a certain permanent deformation of the disk (plastic range). Over 20 °, because of the lesion of the anulus fibrosus tissue, the disk collapses. These values refer to the disk of a normal spine and to forces acting for brief periods. In scoliosis the intrinsic torsion of the vertebrae decreases again angle values capable in changing the elastic behavior, resulting in a permanent disk rotation. So we see a progressive increase in the torsion rigidity module G and, after this, disk istheresis. The istheresis is determined not only by the rotation entity but also by the initial value of G itself that changes in relation to the disk position in the spine and, moreover, to the patient's age. As for disk position, it shows that G values in the disks under vertebrae C2, T4 and LI are so high that one can say that, at those levels, the spine is almost "deaf to torsion. This explains the early structuration of the curves with the apex is situated at the levels previously described and their lack of response to derotating actions. As for the patient's age, the G module shows, from the early age of six to adulthood, a progressive increase, leading to a consequent increase of the torsion rigidity of the disk. This implies that disk capability of reaction to derotating actions decreases with age, from the age of six. 4.

Conclusions

The limits of the orthopedic treatment in idiophatic scoliosis are determined by an estimation of the severity of the curve that involves only the lateral component. The "areas" of therapeutic treatment refer to Cobb's method , with the determination of a "gray-area' and of a "surgical-area". This valutation method confirmed over time its usefulness in determinig which patients must be treated conservatively, in order to stop scoliosis evolution. In this contest it is fundamental to determine the problems correlated with the chronic instability of the adult spine and with the entity of the lateral deviation. Our biomechanical analysis, nevertheless, shows the limits of a valuation method which do not properly analyze the importance of elements such as the residual growth of the vertebrae and the elastic capabilities of the disks. Even if present studies are not capable to define , with adequate approximation, new areas based on the convergence of the different parameters which condition disease evolution, we think that the patient's age and the torsion degree are primary parameters in the decision for a conservative treatment, also in "gray area" curves (Case 1,2, 3).

References 1. 2. 3.

Fineschi G, Aulisa L, Vinciguerra A. La rigidezza del rachide alia torsione. Progr Patol Vert 11: 109-117, 1990 Vinciguerra A, Di Benedetto A, Aulisa L. Sulla determinazione delle caratteristiche elastiche del rachide toracolombare. Minerva Ortop Traumatol 35: 133-138, 1984 Aulisa L, Vinciguerra A, Tamburrelli F, Lupparelli S, Di Legge V. Biomechanical Analysis of the Elastic Behaviour of the Spine with Aging. In: Research into Spinal Deformities 1, J. A. SevastiK and K. M. Diab (Eds.) IOS Press: Amsterdam, 1997, pp. 229-231.

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4. 5. 6. 7. 8.

9.

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Vinciguerra A, Aulisa L, Ceccarelli M. Stabilita e comportamento elastico del rachide. Minerva Ortop Traumatol 37: 717-723, 1986 White AA, Panjabi MM. The clinical biomechanics of scoliosis. Clin Orthop 118: 100-112, 1976 Aulisa L, Di Benedetto A, Vinciguerra A. Un'analisi biomeccanica del sistema tutore-rachide nelle scoliosi idiopatiche. Arch Putti 31: 185-194, 1981 Aulisa L, Vinciguerra A, Valassina A, La Floresta P. II trattamento ortopedico mediante corsetto P.A.S.B. ProgrPatol Vert 12: 135-142, 1991 Di Benedetto A, Vinciguerra A, Pennestr_ E, Aulisa L. Biomechanics of scoliosis using a new type of brace. In: Proceedings of the 8th Canadian Congress of Applied Mechanics. Moncton, N-B, Canada, June 7-12, pp 785-786, 1981 Fineschi G, Aulisa L, Vinciguerra A, Valassina A. Aspetti biomeccanici dei corsetli per il trattamento incruento della scoliosi. Minerva Ortop Traumatol 44: 543-548, 1993

Fig.l G.E. female 11 years old at the beginning of the treatment: A: x-ray before treatment, B: after 2 years of treatment, C: after 5 years of treatment, D: at weaning E: 5 years after the end of the treatment. The favorable age and G modulus, due to the scarce initial rotation (5& Pedriolle), allowed a great improvement of the deformity

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C.A.B. female 12 years old at the beginning of the treatment A: x-ray before treatment, B: after cast correction, C: after 5 years of treatment, D: 10 years after the end of the treatment). The age (menarche 13y.) is favourable and the G modulus (\2JEP.) can still induce an elastic reaction to the corrective forces

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Fig 3 B.D. female, 11 years old at the beginning of the treatment; A: x-ray before the treatment, B: after 3 years of treatment, C: after 4 years of treatment, D: at weaning, E: 7 years after the end of the treatment. The age is favorable (menarche at 13 years of age), while the G modulus is adverse (17Jf. Pedriolle). The good correction, due to the residual growth, has been obtained by the inversion of the rotation in the distal area of the curve, where the elastic properties of the disks have been preserved.

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Cell viability and the physical environment in the scoliotic intervertebral disc Susan R. S. BIBBY, * Adam MEIR, * Jeremy C.T. FAIRBANK, Jill P.O. URBAN Physiology Laboratory and *Dept Orthopaedics, Oxford University, Oxford OX1 3PT, UK

1. Introduction The biomechanical responses of the intervertebral disc is governed by the organisation and composition of the disc's major macromolecules, collagen and proteoglycan. Changes in disc composition or matrix organisation can alter how the disc responds to changes in mechanical stress, and can affect other spinal structures such as ligaments and muscles. Since the disc cells produce and maintain the matrix, any change in their behaviour or viability will ultimately affect the properties of the matrix and thus the disc's composition and biomechanical behaviour. Many factors affect disc cellular activity. In particular, since the disc is avascular, disc cells are at low oxygen and glucose and high lactic acid concentrations; changes to the nutrient supply affects these concentrations and hence cellular activity. The cells also respond to applied loads: load-induced fluid loss and cell deformation, or a rise in hydrostatic pressure, can all affect the rate at which the cells turn over matrix macromolecules. 2. The scoliotic disc In scoliosis, the disc becomes wedged and distorted and is prone to degenerative changes [3]. Here we report on disturbances in cellular activity and viability which may contribute to these changes, and on the factors in the scoliotic disc which may alter cellular behaviour. 2.1. Cell viability in the scoliotic disc A recent study found that cell density was markedly decreased in scoliotic discs, particularly at the curve apex [4]. Cell viability has thus been assayed on both sides of the tissue wedge removed at surgery, using two fluorescent probes which label live and dead cells. A significantly lower number and percentage of live cells was found on the convex than on the concave side, in the apical disc and one above and below in both the inner and outer annulus (Figure 1). No significant differences in side or level were seen in scoliotic discs two or more levels above and below the apical disc, or in tissue removed for back pain or due to trauma. The average percentage of live cells was also lower in scoliotic than other tissue, despite the younger age of most scoliotic patients. These results imply that some aspect of the deformity is inducing this decrease in cell viability. This is further supported by finding that the greatest loss in viability on the convex side was seen in the apical disc, and that cell viability was lower in patients with neuromuscular than idiopathic scoliosis, in whom the curvature is usually more severe and progresses more quickly [1].

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2.2. Matrix macromolecule concentration From the significant decrease in live cells seen on the convex side of the scoliotic disc, one may expect to find a decrease in the concentration of matrix macromolecules here (as some have reported). However, we found that this was not the case, with no consistent or significant differences in proteoglycan or collagen concentration being seen between concave and convex sides in either the inner or outer annulus[l] (Figure 1), or at the curve apex despite the low cell density in the apical disc [4]. Discrepancies in results from different studies may be due to variations in the length of time between curve initiation and surgery, since remodelling of the disc is slow. Macromolecule breakdown may also be affected by cell death. Cells are responsible for the production of both macromolecules and the enzymes which degrade them, hence increased cell death could decrease rates of degradation as well as synthesis. Nevertheless, in the long-term, increased cell death will eventually lead to a compromised disc, as cells are responsible for producing and maintaining the matrix.

% live cells n=20 Figure 1. Comparison of measurements made on the more convex and more concave sides of the outer annulus of disc wedges removed from scoliotic discs during anterior surgery (mean + s.e.m: adapted from [1])

3. Factors which may be involved in loss of cell viability in the scoliotic disc 3.1. Nutrient supply. The nutrient supply to the scoliotic disc is impaired [5], possibly because the endplate which lies between the disc and blood supply can become calcified and thus impede nutrient transport [3]. Transport into the disc was most severely reduced at the disc apex and also at the convexity [5], areas where calcification of the endplate is most intense. In wedges of disc removed surgically during anterior surgery to correct the scoliotic deformity, glucose concentrations were significantly lower on the convex side of the wedge (Figure 1) [1]. Lactate concentrations measured in similar tissue samples showed a greater concentration in the apical disc than in discs 2 levels above and below it, while oxygen concentrations measured in vivo at surgery were lowest in the apical disc [1]. 3.2. Mechanical Stress. It has been shown that mechanical pressure influences calcification in cartilaginous tissues and affects matrix synthesis in disc cells, suggesting possible mechanisms by which abnormal disc pressures could have a role in disc deformity. Pressure profiles across scoliotic discs have been measured in scoliotic patients undergoing corrective surgery, using similar techniques to those used in non-scoliotic discs [2]. The profiles measured were very different from the idealised profiles measured previously in

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healthy discs [2], where pressure is hydrostatic across most of the disc. Some discs had no hydrostatic regions at all, which was surprising considering the age of the patients. The hydrostatic pressures recorded are shown in Table 1. Pressures measured in patients 1 and 3 were considerably higher than those measured in awake recumbent subjects [6], even though the patients were anaesthetized and had been given muscle relaxants. The pressure was zero in the discs of the 1 non-scoliotic anaesthetised patients undergoing discectomy and fusion for back pain. Tablel: Hydrostatic Pressure levels measured in anaesthetised patients during corrective anterior scoliotic surgery. Results are normalised to those measured in awake subjects lying prone [6] Cobb Disc levels Hydrostatic Pressure angle 1 N 3.0 2.7 IS 55° 16y T11/12T12/L1' Ll/2 N 0.2 N IS 78° TH/12T12/L1' Ll/2 2 17y NM 60° 2.6 1.7 N 2.6 13y 3 T12/L1 Ll/2* L2/3 L3/4 44° IS 0.8 0.9 1.0 23y 4 T10/11T11/12'T12/L1 NK 0.3 1.1 0.1 n/a 18y 5 T11/12T12/L1' Ll/2 *- apical disc N - no hydrostatic region IS - idiopathic, NM - neuromuscular, NK, neuromuscular kyphosis Patient no.

Age

Diagnosis

4. Conclusions.

It is generally assumed that scoliosis is caused by asymmetrical loads on the concave side of the curve; thus it may be expected that increased cell death would be seen on the concave side of the disc. However, the cells of the convex side are also exposed to abnormal stresses, being under continuous high tensile and shear loads, due to stretch on this side and the rotation of the spine. There also appears to be a decreased nutritional supply on the convex side of the disc, which may contribute to the loss of cell viability seen here. This may be related to a loss in endplate permeability, possibly resulting from pressure-induced calcification. This study does not allow us to differentiate between causes of cell death; however it does imply that both disc deformation and/or loading, and a decrease in nutrients and build-up of waste products, are involved. It may be a combination of factors that eventually lead to the deformed disc seen in the scoliotic spine. References S. R. S. Bibby, J. C. T. Fairbank, and J. P. G. Urban Cell viability in scoliotic discs in relation to load, Trans ORS (2001c) 76. D. S. McNally Biomechanics of the intervertebral disc- disc pressure measurements and significance, (1995e) 42-50. S. Roberts, J. Menage, and S. M. Eisenstein The cartilage end-plate and intervertebral disc in scoliosis: calcification and other sequelae, J.Orthop.Res. 11 (1993a) 747-757. M. R. Urban, J. C. Fairbank, S. R. Bibby, and J. P. Urban Intervertebral disc composition in neuromuscular scoliosis: changes in cell density and glycosaminoglycan concentration at the curve apex, Spine 26 (2001b) 610-617. M. R. Urban, J. C. Fairbank, P. J. Etherington, F. L. Loh, C. P. Winlove, and J. P. Urban Electrochemical measurement of transport into scoliotic intervertebral discs in vivo using nitrous oxide as a tracer, Spine 26 (2001d) 984-990. H. J. Wilke, P. Neef, M. Caimi, T. Hoogland, and L. E. Claes New in vivo measurements of pressures in the intervertebral disc in daily life, Spine 24 (1999f) 755-762.

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Brain-stem dysfunction and idiopathic scoliosis Emm. K. Dretakis Heraklion-Crete/ Greece The coexistence of scoliosis with neurologic disorders affecting different levels of the nervous system has been very often refered to in the literature [2,12,15,16,33,40,42]. During the last thirty years more than 30 cases of a clinical syndrome characterized by the coexistence of complete lateral gaze palsy and thoracic scoliosis have also been described (table 1). It is interesting that in all these patients the absence of lateral eye movements- on both sides- was noticed before the diagnosis of the spinal deformity. No congenital anomalies of the spine were found in any of these patients. In 1970 [9] we described our first three cases of the syndrome ( family I), in 1974 [10] we reported five cases ( families I and II) and in 1984 [12] we reported a total of eight casesseven boys and one girl - and reviewed the relevant literature (table 2 ). All these patients were Greeks in origin and permanent inhabitants of Greece. In all eight patients, absence of lateral eye movements and horizontal nystagmus were noticed soon after birth, while the spinal deformity became evident later, developing parallel to the evolution of the stato-kinetic function of the affected children. The age of the patients at the time of diagnosis of the spinal deformity varied from seven months to ten years, with a mean age of three years. It is possible that the scoliosis started developing during infancy in all eight patients and that its early diagnosis was missed in seven of the eight cases, as the curve has been initially very small and the parents not being aware could not recognize its presence. Thus, it could be said that scoliosis associated with lateral gaze palsy belongs to the infantile progressive type differing in that it is a right thoracic instead of being left thoracic, the location commonly seen in the usual type of infantile scoliosis [19,23,24]. Neurological examination of these 8 patients showed complete absence of the lateral eye movements on both sides. The pupils were round and equal in size, reacting to light and accommodation. Horizontal nystagmus was observed both spontaneously and on testing. In all three patients of the family I, slight tremor of the head was seen, often accompanying voluntary movements of the left arm. No evidence of cerebellar dysfunction was detected. The gait, tendon reflexes and motor power of the limps were normal in all 8 patients. The intelligence of all 8 patients seemed to be on the borderline of the normal. Based on the clinical neurological examination of the 3 siblings of the first family, we attributed their ocular problems to a congenital defect, located at the mid-brain and namely in the anterior gemina extending to the pons and discussed the possibility these lesions to*be closely associated with the coexisting scoliosis. Dretakis (1970 )[9J. EEG investigation in seven of the eight patients exhibited slow waves with bilateral paroxysmal subcortical discharges suggesting subcortical dysfunction. EMG of the external ocular muscles of the two patients of the family II indicated that ocular dysfunction was due to supranuclear abnormality.

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Computerized tomography of the brain in the five patients of the families I and II showed no abnormality, but recent MRI in one of the patients of the family I showed leveling of the anterior border of the medula oblongata at the pyramidal level with accompanying enlargement of the pre-bulbar sistern- in comparison with MRI of the brain of his normal sister (Fig. 1-2). In three of the five families more than one children presented the described syndrome. The familiar character of this entity indicated the presence of an autosomal recessive trait of inheritance and this was supported by the existence of parental consanguinity refered to in seven of the eight patients included in the current study and also stated by Tezuka (1971)[40] Rilley & Swift (1979) [31], Granat et al (1979) [19] and Hamanishi et al (1993) [20]. is also interesting that a girl with Golderhart's syndrome [is], associated with thoracic scoliosis, was cousin of the patients of the family II. Seven of the eight patients were fitted with Milwaukee braces and followed-up regularly. With the proper use of the brace the scoliosis was corrected in one case and improved in two cases. Carpenter (1977) [5] has shown that a lesion of the medial longitudinal fasciculus (MLF) at the pontine level produces paralysis or paresis of ocular adduction with horizontal nystagmus. Cohen et al (1968) [7] have also found that lesions in the paramedian zone of the reticular formation at the pontine level (PPRF) resulted in ipsilateral paresis of lateral movements of the eye, with spontaneous nystagmus to the contralateral side. All eight patients described by us had absence of lateral eye movements and spontaneous horizontal nystagmus. Therefore, the ocular dysfunction of our patients and of those described by other investigators may well have resulted from organic bilateral lesions at the brain-stem and that the coexisting scoliosis could be related to these lesions. Yamada et al (1970) [41] based on clinical observations and experimental studies suggested that the equilibrium dysfunction that is observed in most of the scoliotic patients is caused by a disturbance at the brain-stem level rather than in the spine. Yamada described two types of equilibrium dysfunction: 1. a functional disorder and 2. an organic lesion at the center regulating equilibrium in the brain-stem and stated that both types are closely related with the progress of scoliosis. Petersen et al (1979) [30] based on the aforementioned observations curried out an EEG study in patients with idiopathic scoliosis within the frame of a larger study of the equilibrium function in idiopathic scoliosis. The authors found that 30 per cent of the scoliotic children exhibited at least one of the patterns "increase of low frequency activity" and "paroxysmal activity" in comparison with 17 per cent of children used as controls. Interestingly an inverse relationship was observed between the severity of scoliosis and EEG findings. The authors concluded that centrally located subcortical structures are involved in the pathologic process in idiopathic scoliosis. We also investigated the possible pathologic EEG findings in children with idiopathic coliosis and their correlation to the magnitude and location of the spinal curve. Dretakis et al (1988). [13] In the group of scoliotics the percentage of pathologic electro-encephalograms found to be higher than that of the control group (33% to 14%) being much higher after activation (57% to 22%).

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In lumbar, thoracolumbar and double curves focal EEC changes predominated whereas in thoracic curves there was a higher incidence of bilateraly synchronous discharges. These data support the possibility idiopathic thoracic scoliosis to be associated with brain-stem dysfunction. Sahlstrand et al (1979) [34] working on the hypothesis that a functional asymmetry or disturbance at some level in the vestibulospinal reflex arc might be a factor contributing in the development of idiopathic scoliosis studied the effect of caloric stimulation of the labyrinth on the postural sway in scoliotic children. It was observed that scoliotic patients tended to have an increased postural sway during labyrinthine stimulation on the convex side. Compared to the effects on the concave side, these findings indicate according to the authors a dysfunction in the labyrinths or in the efficiency with which the scoliotic child succeeds in conteracting a vestibular imbalance with the postural control mechanism. Herman et al (1985) [22] attributed the abnormal postural reaction which is observed in patients with idiopathic scoliosis to asymmetric deficits in central nervous system centres concerned with visual-vestibular interactions. They proposed that disturbance at a higher level of the central nervous system may be responsible for the reported electroencephalographic abnormalities, visual-spacial impairement, motor adaptation and learning deficits. Barrack et al (1988) [4] considering vibratory response a sensitive indicator of posterior column function evaluated the vibratory sense of scoliotic children using a biothesiometer (Bio-medical instrument company Newbury Ohio USA). The authors found significant differences between scoliotic children and controls at all sites tested and concluded that these findings support the existence of a central aberration in posterior column function, which may be a primary cause of idiopathic scoliosis. Me Innes et al (1991) [25] using the bio-thesiometer found that the only reliable site for measurement was the metatarsophalangeal joint. At that site the vibratory thresholds were significantly higher (instead of being lower according to Barrack et al) in scoliotic children compared with normal controls. No significant asymmetry in vibratory thresholds was also found between concave and convex or right and left sides. The authors state that the bio-thesiometer is not sufficiently reliable to detect a possible difference in the vibratory thresholds in scoliotic patients. Using the same type of bio-thesiometer, we also studied the thresholds of vibratory sensitivity in children with idiopathic scoliosis. Dretakis et al ( unpublished data) [M] We found that the means of the thresholds measured at each bone prominence either on the right or on the left side were not significantly different between scoliotic children and normal controls. However, scoliotic patients showed significantly lower thresholds at the left toe. It was also found a significant asymmetry of the vibratory thresholds in the ulnar styloid process and in the medial malleolus when comparing between scoliotic and normal children. Geissele et al (1991) [17] using MRI investigated the anatomy of the brain in patients with idiopathic scoliosis. In 26% of the patients, they found asymmetry at the ventral pons or medulla in the area of corticospinal tracts. Cheng et al (1999) [6] found that 7,3% of the scoliotc patients who were studied by MRI had tonsillar ectopia, the degree of displacement ranging between o,5 mm and 4,4 mm below the foramen magnum. They also found that in cases of severe scoliosis the tonsillar ectopia was associated with abnormal somatosensory function in 33% of the patients.

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With the virtual elimination of poliomyelitis from the developed world, the vast majority of cases of scoliosis belong to the idiopathic type [l 1,21,29,37]. Although idiopathic scoliosis remains a pathologic condition of unknown etiology , a considerable number of factors, including genetic, mechanic, metabolic, neurologic and others have been implicated to contribute in the development of this deformity [1,3,13,27,28,35,42].

It is possible that in every case of idiopathic scoliosis different combination of causative factors is at work for the development of this deformity. It is also possible that asymmetry in maturation of the nuclei concerned may disturb the postural reflex mechanism resulting in development of scoliosis. Compensatory mechanisms that might be at work could possibly explain differences observed as regards the establishment and course of the deformity. It has been referred - for instance- that in the compensatory changes that follow asymmetric lesions the vestibular nuclei can take over some of the functions of the cerebellum and the cerebellum can alleviate the symptoms of unilateral labyrinthectomy. Roberts (1978) [32]. Based on the above mentioned clinical and experimental studies, we conclude that idiopathic scoliosis may be the consequence of a primary disturbance of the central mechanism, controlling the postural reflexes which is anatomically located in the brain-stem. Every child with idiopathic scoliosis- even with mild curve- should be submitted to a thorough neurophysiological investigation.

References 1. 2.

Bagnall KM., Raso V.J., Moreau M. et al, Melatonin levels in idiopathic scoliosis, Spine 21,1996, 197-1978. Barnes P.O., Brody J.D., Jaramillo D., Akbar J.B., Emans J.B., Atypical idiopathic scoliosis, MRI evaluation, Radiology 186, 1993,247-53.

3.

BarriosC., Arrotegui J.I., Experimental kyphoscoliosis induced in rats by selective brain-stem damage, mt. Orthop. 16, 1992, 146-51.

4.

Barrack RL., Wyaff M., Whitecloud T.S. et al, Vibratory hypersensitivity in idiopathic scoliosis, J~ Pediatric Orthop. 8,1998, 389-395.

5. Carpenter M.B., Human neuroanatomy, Williams and Wilkins, Baltimore, 1977. 6. Cheng I.C.Y, Quo X., Sher A.H.L. et al, Correlation between curve severity, somatosensory evoked

7.

potentials and Magnetic Resonance Imaging in adolescent idiopathic scoliosis, Spine 24, 1999, 1679-1684. [Cohen B., Komatzuzaki A~, Bender M., Electro-oculographic syndrome in monkeys after pontine reticular

8.

formation lesions, Arch. Neur. 18,1968, 78. Crisfield R.J., Scoliosis with progressive external ophthalmoplegia in four siblings, J.Bone Joint Surg. 56-

9.

B, 1974,484-487. Dretakis Emm. K., Familial scoliosis associated with encephalopathy in three children of the same family,

Acta Ortop. Hellenica 22, 1970,51-55. 10. Dretallis Emm. K., Kondoyannis P.N., Familial scoliosis associated with encephalopathy in five children of two families, J. Bone Joint Surg. 56-A, 1974, 1747-50. 11. Dretakis Emm. K., Apostolopoulos P., Zarkadoulas V. et al, Screening for scoliosis in school children in Athens, Proc. Irst Europ. Congress on scoliosis and kyphosis, Dubrovnic, Oct. 5-9., 1983, 86-87. 12. Dretakis Emm. K., Scoliosis associated with congenital brain-stem abnormalities. Report of eight cases,

426

E.K. I)rctciki.\ / Hrtiin-Srcm l)\-\fnncruin and Iclinputlin .SYf»//m/\

Tnt. Orthop. 8, 1984,37-46. 13. Dretallis Emm. K., Paraskevaidis C.H., Zarkadoulas V. and Clrristodoulou N., Electroencephalographic study of school children with adolescent idiopathic scoliosis, Spine 13, 1988, 143-145. 14. [Dretakis Emm. K., Unpublished data on vibratory sensitivity in children with idiopathic scoliosis, 2002. 15. Duvoisin R.S. and Mardsen C.D., Note on the scoliosis of Parkinsonism, J. Neural., Neurosurg., Psychiatr. 38, 1975,787-89. 16. Farley F.A., Song K.M., Birch J.G., Browne R., Syringomyelia and scoliosis in children, J. Pediatric. Orthop. 15, 1995, 187-192. 17. Geissele AB., Kransdorf M.J., Geyer C.A. et al, Magnetic resonance Imaging of the brain-stern in adolescent idiopathic scoliosis, Spine 16,199~, 761-763. 18. Goldenhar M, association malformative de I'oeil et de l~oreille en particuher le syndrome dermoide epibulbaire- Appendices Auriculaires- Fistula autis congenita, J, Gen Hum 1,,1952, 243. 19. Granat M., Friedman Z., Aloni T., Familial infantile scoliosis associated with bilateral paralysis of conjugate gaze, J. Med. Genet 16, 1979, 448-452. 20. Hamanishi C., Tanaka S., Kasahara Y., Shikata I., Progressive scoliosis associated with lateral gaze palsy. SpinelS, 1993,2545-48. 21. Harrington P.R., The etiology of idiopathic scoliosis, Clin. Orthop. 126, 1977, 17-25. 22. Herman R., Mixon J., Fisher A., Maulucci R. and Stuyck J., Idiopathic scoliosis and the central nervous system. A motor control problem, Spine 10, 1985, 1-14. 23. Hopper W.C., Lovell W., Progressive infantile idiopathic scoliosis. Clin.Orthop. 126, 1977, 26-32 24. James J.I.P., Infantile idiopathic scoliosis, Clin. Orthop. 77, 1971, 57. 25. Me Innes E., Hill D.L., Raso V.J. et al, Vibratory response in adolescents who have idiopathic scoliosis, J.Bone Joint Surg. 73-A, 1991, 1208-1212. 26. Miller N.H., Genetics of familial idiopathic scoliosis, Spine 25, 2000,2416-18. 27. Nachemson A., Sahlstrand T., Etiologic factors in ado-scent idiopathic scoliosis, Spine 3, 1977, 176-182. 28. Nachemson A., Poppe M.H., Concepts in mathematical modeling, Spine 16, 1991, 675-676. 29. Nordwall A., Studies in idiopathic scoliosis relevant to etiology, conservative and operativetreatment. Acta Orthop. Scand., 1973, Suppl. 150. 30. Petersen I., Sahistrand T. and Seilden U., Electroencephalographic investigation of patients with adolescent idiopathic scoliosis, Acta Orthop. Scand. 50, 1979, 283-293. 31. Rilley E., Swift M., Congenital horizontal gaze palsy and kyphoscoliosis in two brothers, J.Med. Genet. 16, 1979,314-316. 32. Roberts T.D.M., Neurophysiology of postural mechanisms, Butterworths, 1978. 33. Robin G.C., Scoliosis and neuurological disease. A. Haisted press Book, 1975. 34. Sahlstrand T., Petruson B.., Ortengren R., Vestibulospinal reflex activity in patients with adolescent idiopathic scoliosis, Acta Orthop. Scand. 50, 1979,275-281. 35. Sevastic J., Agadir M., Sevastic B., Effects of rib elongation on the spine I. Distortion of the vertebral alignment in the rabbit, Spine 15, 1990, 822-825. 36. Sharpe J.A., Silversides J.L., Blair R.D., Familial paralysis of horizontal gaze. Neurology 25, 1975, 1035-

40. 37. Smyrnis P., Valavanis J., Mexoppoulos A., Siderakis 0., Giannestras N., School screening for scoliosis in Athens, J. Bone Joint Surg. 61-B, 1979, 215. 38. Steffen H.,Rauterberg I. Et al, Familial congenital horizontal gaze paralysis and kyphoscoliosis, Neuropediatrics 29, 1998, 220-222. 39. Steindler A, Kinesiology of the human body, Charles Thomas, Sprinfieid, 1955, 241. [40] Tezuka A., Development of scoliosis in cases with congenital organic abnormalities of the brain-stem.Tokushima J.

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Exp. Med. 18,1971,49-62. 40. Yamada K., Yamamoto H., A neurological approach to the etiology and therapy of scoliosis. 4~ Scolios. Res. Soc. Meet., Toronto, 1970. 41. Yamada K., Yamamoto H., Nakagawa Y., Tezuka A., Tamura T. and Kawata S., Etiology of idiopathic scoliosis, Clin. Orthop. 184,1984, 50-57.

Table I. Lateral gaze palsy-scoliosis syndrom 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Dretakis Emm. Ada Orthop. Hellenica 22: 51-551 1970 Dretakis Emm., Kondoyannis N.J. Bone Joint Surg. 56-A: 1747-1750,1974 Dretakis Emm. Intern. Orthop. 8: 37-46,1984 Yamada K-3 YamamotoH.4~Scol. Rec. Soc. Meet. Toronto-) 1970 Crinsfield R. J. J. Bone Joint Surg. 56-B: 484-487, 1974 Sharpe J. A, Silversides J. L, Blair D. G. Neurology 25:1035-40,1975 Rilley E.-j Swift M. J. Med Genet. 16: 314-316,1979 Granat M^ Friedman Z.-j Aloni T^ J. Med. Genet. 16: 448-52, 1979 Hamanishi C. .Tanaka S.-jKasahara Y., Shikata J. J. Spine 18: 2545-8,1993 Steffen H., Rauterberg I. et al Neuropediatrics 29: 220-222, 1998

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Th.B.GrivaslEd.i Research into Spinal Deformities 4 IOS Press. 21102

Finite element simulation of various strategies for CD correction V. Lafage ', J. Dubousset2, F. Lavaste ', W. Skalli ' ' Laboratoire de BioMecanique, ENSAM-CNRS, Paris, FRANCE 2 Hopital Saint Vincent de Paul, Paris, FRANCE

Abstract. The scoliosis surgery using the Cotrei-Dubousset instrumentation ''"21 is a complex three dimensional correction. This surgery was first simulated for a given patient using a personalized finite element model'31 : the geometry was extracted from a 3D stereoradiographic reconstruction'41 and mechanical properties were personalized using lateral bending tests'51. Finally, three alternative surgical strategies were simulated in order to analyze their effects on spine postoperative configuration. First results are promising and should allow surgeons to objectively analyze various strategies or techniques.

1. Introduction Cotrei-Dubousset scoliosis surgery is a three dimensional correction161 which apply a combinaison of translation and rotation on the whole spine to correct the vertebral body line and the vertebrae orientations. The surgical strategy (hooks and screws localization, vertebrae instrumented) planning may depend on the surgeon know-how with difficulty to assess an objective decision. The aim of the study is to propose a finite element model which simulates the surgical act for a given patient, to validate it, then to simulate alternative possible strategies for correction and to analyze the predicted effects of those alternative strategies. 2. Material and methods 2. / Clinical Data One scoliotic patient of Saint Vincent de Paul hospital corrected by Cotrei-Dubousset instrumentation was considered. This patient presented a right T4/L1 idiopatic scoliosis with an apical disk in T9/T10 and a Cobb angle of 45°. As for the CD instrumentation, it was placed in T5/Llwith an upper claw in Tl and lower one in T12/L1. Intermediate hooks were in T7 and T10 on the convex side and on T9 on the concave one. 2.2 3D Geometry The general approach for model construction was the same as that previously described by Leborgne & al [3l The geometric model of the spine and pelvis was obtained from a 3D reconstruction from biplanar X-rays, markedly improved using NSCP technique [4 l This geometrical model, represented in figure la, constituted the base for the finite element mesh t7>8), as represented in figure Ib and Ic.

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2.3 Mechanical personalization In a first step material properties of vertebrae, disks and posterior elements were introduced from in vitro experiments ^. Preoperative clinical bending tests were used to assess specific mechanical characteristics of the patient. These tests were simulated in the following way: Tl and pelvis displacements (measured on Xrays) were introduced as boundary conditions in the model, and difference was quantified between spine configuration yielded by the model and that measured on Xrays in bending Mechanical characteristics of soft tissues were then adapted locally or regionally [sl until the error between simulation and radiographic measurement tend to 5° for the vertebrae orientation and 10 mm for the body line. 2.4 Simulation of surgical correction To mimic the surgical procedure of correction the five steps of surgery*21 were defined as follow: • Surgical preparation: Under anesthesia, in ventral decubitus, the patient is fixed under traction, vertebrae within the instrumented area were then exposed and the surgeon proceeded to an articular facets resection. To simulate this resection, contact elements and capsular ligaments of the instrumented area were deleted. The traction was simulated as a displacement of CO along the axis imposed by the table's geometry. • Hooks placement and rod geometry: This second step needed no calculation. Hooks of the concave side were modeled using an elastic beam. • Distraction: During the surgery, the first rod was firstly inserted in extreme hooks or screw, then the spine was pushed toward the rod until the rod was hooked. To simulate this step of distraction, for each intermediate hook (from bottom to top), its posterior node was displaced toward the rod. • Rod derotation: During the surgery, the first rod was rotated toward the concave side of about 90 °. For the simulation, the link between the rod and the hook or the screw was represented by a sliding pivot. A local axis was defined by the two end nodes of the rod, the concave rod was rotated of 90 ° around his local axis. • Hooking the second rod: finally, the second rod was hooked on the convex side of the scoliotic curve and transverse mechanisms of fixation were fixed.

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V7. La fage er at. / Finite Element Simulation i>f Various Strategies for CD Correction

2.5 Simulation of alternative surgical strategies To analyze the effects of the alternative surgical strategy, surgeon asked us to simulate the surgery correction with various choices of end vertebrae: • Case 2: lower claw in L1-L2 (figure 2) instead of Tl 2-L1 • Case 3: two hooks in L1 instead of a claw (figure 2) • Case 4: upper claw in T4 (figure 2) instead of T5 One may notice that case 3 represented the strategy used at the earlier times of the CD correction.

T5^

TS^5 &

£f

-

\ T12^«

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Ll^-

o Casel

\ Ll

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e ff T5 a^ \

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e £? T4 a^ %

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Figure 2 : The 4 Surgical strategies. Casel = The real surgery. Case2,3 and 4 = alternative strategies.

2.6 Validation The results of the bending test simulations were compared to the measurements extracted from the lateral bending films in terms of vertebral body line and vertebrae orientation. As for the surgery simulation, results were compared with the post-operative 3D reconstruction obtained using stereoradiography. 3. Results and discussion 3.1 Mechanical Personalization For the posterior ligaments and for the disk stiffness in torsion, we found no differences between this specific patient and a normal one. As for the stiffness in bending, we found 2 areas (T1-T7 and T12-L3) much stiffer than in the standard model. These qualitative results were in adequation with the surgeon analysis to appreciate the reducibility of the scoliotic curve. For the vertebra body line in the frontal plane, this mechanical personalization allowed to reduce mean errors from 11.3mm (max 25mm) to 4.3 mm (max 10mm). The same phenomena were obtained for the vertebrae orientations: mean errors of vertebrae axial rotations were reduced from 10.9° (max 25°) to 2.1° (max 5°) and mean errors of vertebrae lateral bending from 5.1° (max 15°) to 2.3° (max 5°).

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3.2 Surgical Simulation Simulation results were compared with the post-operative 3D reconstruction. For the vertebral body line (figure 3), mean errors were 3.9 mm (max 5mm) in the sagittal plane and 4.1 mm (max 8 mm) in the frontal plane. As for the vertebrae orientation (figure 4), mean errors were 2.3° (max 4.8°) for the axial rotation and 2.1° (max 4.9° )for the lateral bending. Differences between the simulated surgery and the real one may be due in part to an excessive simulated correction: the frontal balance was better in the simulated case as well as the correction of the vertebrae axial rotation. The maximal error in axial rotation (in T12) was localized on the lower claw (T12-L1) : the hook mechanical action may need to be better modeled. Axial Rotation Sagittal plane

-50

0

50

Lateral Bending

Frontal plane

-50

0

50

' • • • Post-operative reconstruction «•• Surgery Simulation -10 -

Figure 3 : Vertebral body line in frontal and sagittal plane. FF-M vs post-operative 3D reconstruction

5

0

5

10-20

-10

D Figure 4 : Vertebrae axial rotation and lateral bending. FEM vs post-operative 3D reconstruction.

3.3 Simulation of alternative surgical strategies In this preliminary study, results were analyze qualitatively. • Case 2 yielded excessive vertebrae axial rotation and frontal imbalance • Case 3 improved slightly the frontal balance • Case 4 yielded a slight frontal imbalance and a significant sagittal imbalance These first results allowed the expert surgeon to confirm his intuition and may indicate that either strategy corresponding to case 1 or to case 3 could have been considered. 4. Conclusion The results of this preliminary study are relevant for two reasons. First, it demonstrated that a finite element model can simulate the specifc mechanical behavior of a given patient. To do this, the model must be personalized not only geometrically but also mechanically. Secondly, the coherence between the simulations and the post-operative 3D

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V Ltifiifje e! al. / Finite Element Simulation of Various Strategies tor CD Correction

reconstruction proves the feasibility of this finite element modeling approach as a qualitative and quantitative predictive tool of correction. As for the alternatives strategies, we didn't found in literature any reference on the effect of the surgical strategy. Nevertheless the model prediction was coherent with surgeon feeling. After extensive validation, the model should constitute an invaluable predictive tool for surgery planning. 5. Acknowledgements The geometry of the model was developed in collaboration with the Laboratoire de recherche en Imagerie et Orthopedic (LIO) of Pr J. de Guise (ETS, Montreal, Canada). References 1. 2. 3. 4. 5. 6 7. 8 9.

Cotrel Y, Dubousset J, Guillaumat M. New universal instrumentation in spinal surgery. Clin Orthop 1988;227:10-23. Dubousset J, Cotrel Y. Application technique of Cotrel-Dubousset instrumentation for scoliosis deformities. Clin Orthop 1991:103-10. Le Borgne P, Skalli W, Lecire C, Dubousset J, Zeller R, Lavaste F. Simulation of CD Surgery on a personalized Finite Element Model : Preliminary results. 4th International Symposium on three dimensional scoliotic deformities. Vermont, USA, 1998. Mitton D, Landry C, Veron S, Skalli W, Lavaste F, De Guise JA. 3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes. Med Biol Eng Comput 2000:38:133-9. Le Borgne P, Skalli W, Dubousset J, Dansereau J, Zeller R, Lavaste, F. Finite Element Model of scoliotic spine: Mechanical Personalization. 4th International Symposium on three dimensional scoliotic deformities. Vermont, USA, 1998. Stokes IA, Bigalow LC, Moreland MS. Three-dimensional spinal curvature in idiopathic scoliosis. J Orthop Res 1987;5:102-13. Descrimes JL. Modelisation par elements finis du rachis et de la cage thoracique pour I'etude des deformations scoliotiques. PhD Thesis, 199S Ecole Nationale Supdrieure des Arts et Metiers Le Borgne P. Modelisation par elements finis de la correction chirurgicale de la scoliose par instrumention Cotrel-Dubousset. PhD Thesis, 1998 Ecole Nationale Superieure des Arts et Metiers Koubaa W. Modelisation geometrique et mecanique tridimensionnelle par elements finis du rachis thoracique. PhD Thesis, 1995 Ecole Nationale Superieure des Arts et Mftiers

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Idiopathic Scoliosis. Segmental Fusion With Transpedicular Screws A.Christodoulou2,A.Ploumis2,C.Zidrou1, J.Terzidis2, J.Pournaras1 1. A' Orthopaedic Department of Aristotelian University ofThessaloniki 2. Orthopaedic Department of Hippokration General Hospital ofThessaloniki Abstract. The purpose of this study is to evaluate whether the surgical correction of the scoliotic curve with the use of segmental pedicle screw fixation system is effective. We studied 20 patients (19 girls, 1 boy) with a mean age of 14,6 years (range from 13 to 22). The spinal deformities were evaluated by Cobb method with anteroposterior and lateral bending radiographs. There were 13 right thoracic curves and 7 left thoracolumbar curves. The width of the pedicles was estimated in all patients by computerized tomography of the thoracic and lumbar spine. Posterior instrumentation (Moss-Miami transpedicular system) was used and additional thoracoplasty was performed in 2 patients. The transpedicular screws were placed between T2 and L5. Intraoperatively the image intensification was indispensable and the wakeup test was always conducted. All the patients were assessed both clinically and radiographically at 3,6,9,12 months and annually until now. The average follow-up was two years. There was an average correction of 73% of the primary curve (pre-op standing average 59° (range from 42° to 87°), lateral bending average 33° (range from 10° to 75°), post-op average 13° (range from 6° to 30°), at last examination average 14° (range from 6° to 33°). Infection and neurological complications were not noted. No major complications were observed. Exact evaluation of the pedicles by CT scan is an essential prerequisite for transpedicular screw insertion. The correction of idiopathic curves with the use of segmental pedicle screw fixation system is a very effective method(correction > 70%) It seems that control of the three columns of the spine by the transpedicular screws offers sufficient apical translation and coronal realignment.

1. Introduction The surgical correction of scoliosis in adolescence remains a last resort treatment. This is usually performed when there is a significant curve (>40°) or a rapidly progressive curve. The aim of such surgical correction has many facets. The first one is to stop the irremediable progression of the angulation of scoliosis. The second one is to obtain through a surgical technique the reequilibrium of the curves in the frontal and sagittal planes and also to obtain derotations of the vertebrae. The final aim is to obtain the correction of the structural deformity. To obtain these results different surgical methods were developed in the 1950s. Until the 1980s the Harrington rod procedure was considered the gold standard. Through a simple posterior surgical approach, this instrumentation had advantages, like rapidity of application. The main disadvantages of the Harrington procedure are a fragile construction, neurologic risks by distraction, difficulties in restoration of the sagittal plane curves and the requirement of postoperative cast support for a significant period. Hook insertion techniques are standard, familiar and generally accepted. However, hook displacement may occur during curve reduction maneuvers. By definition all hooks intrude the spinal canal and may be associated with neurologic complications.

Pedicle screw fixation in the lumbar spine has received widespread acceptance in the treatment of fractures and degenerative conditions, but there has been less documentation of it for the treatment of AIS15. In theory, pedicle screw fixation offers more stable fixation in the lumbar spine with the possibility of better correction over a shorter segment9 while remaining completely external to the canal. Screws inserted through the three columns of the spine, are inherently stable and resist loads in all planes, thus offering a potential advantage in comparison with hooks. Although accurate pedicle screw insertion may present problems, numerous authors report a low complication rate and a better three-dimensional correction as well as a shorter fusion length and less loss of correction in comparison to hook fixation2'3'46'78'1112 Thoracic pedicle screw instrumentation , is sometimes regarded as having a higher risk of serious neurologic injury10. Suk et al12 published 15 cases of exclusively pedicle screw instrumented idiopathic scoliosis with fusion extending to the thoracic spine. Based on increasing experience with pedicle screw instrumentation in scoliosis surgery, the authors of the present study have extended its application from the lumbar to the thoracic spine. The purpose of this study is to evaluate whether the surgical correction of the scoliotic curve with the use of segmental pedicle screw fixation system is effective. 2. Material and Method Twenty patients with adolescent idiopathic scoliosis who were operated on by the senior author during the period 1998-2000 were included in this study. They were 19 females and one male with a mean age at the time of surgery of 14,6 years (range, 13-22). The curves appeared to be right thoracic in 13 patients and left thoracolumbar in 7. The preoperative assessment included apart from the routine blood tests and ECG studie^poster^anterior and lateral films with the patients standing as well as posteroanterior films in lateral bending positions for evaluation of the reducibility of the curves. The cobb method was used to measure the angles of the curves (fig.2). Evaluation of the vertebral rotation with the Perdiolle method was intended to be performed initially, but the frequent postoperative implant shadow covering of the pedicles made it impossible. The width of the pedicles was estimated in all patients by computerized tomography of the thoracic and lumbar spine (fig. 1). MRI was performed in all patients for diagnosis of spinal dysraphism. Posterior instrumentation (Moss-Miami transpedicular system) was used in all patients. An additional thoracoplasty was performed in 2 of them. The Moss-Miami is a universal spinal instrumentation system consisting of a titanium 5,5 mm solid rod, hooks and pedicle screws of different lengths and diameters. The screw rod interface is fixed by double (inner and outer) nuts. The principles of Cotrel et all5 were followed for curve correction by rod rotation and slight distraction on the concave side and compression when this was necessary on the concave side. Through a posterior approach, the chosen levels were prepared and visualized. The point of introduction of the pedicle screw was defined by the transaction between the horizontal line of the transverse process level and the vertical line passing through the articular facet. The convergence of the introduction pin was depended on the rotation of the scoliotic vertebra, and was parallel to the upper plateau of it. First, the pedicle was entered and widened with an awl, and the pedicular cavity was explored with a sounder to verify an intact medial, lateral.

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superior and inferior cortex. After screw insertion, the correct placement and length was confirmed with intraoperative fluoroscopy in both planes. Facet resections were performed to give mobility and enhance the fusion. Posterior element decortication was performed at the end of instrumentation to decrease blood loss, and then autologous bone grafts were inserted. Intraoperatively the wake-up test was conducted. Suction drain was used in none of the patients. A peridural catheter was placed through the ligamentum flavum of the first free intervertebral space. The peridural catheter was left in place for an average of two days after surgery. Pain control was obtained with morphine solutions. All blood transfusions were done by autotransfusions of predonated blood apart from two patients. The patients began walking without brace protection during the first 5 postoperative days. All the patients were assessed both clinically and radiologically at 3,6,9,12 months and annually until today. The results were analyzed by comparing the pre and post-operative radiographs regarding the curve measurements and the balance of the spine 3. Results The primary curves measured 42° - 87°, (average 59°) on the standing films and 10°75° (average 33°) on the lateral bending films preoperatively. These curves were corrected to 6° - 30° (average 13°) postoperatively (fig.3) (73,4% correction). At the last follow up (average two years) the average curve was 14° (range 6° - 33°). Screws of 5 mm diameter were inserted in the thoracic spine with exception at T4 T5 T6 levels in which the 4,35 mm screws were used (paediatric instrumentation set). 5mm or 6mm screw were inserted in the lumbar spine. Transpedicular screws were placed between T2 and L5 in this series of patients. No major complication such as abnormal neurologic signs or infection were noted. The patients were free of pain and fatigue and had satisfactory cosmetic result with balance spine. Cases of screw dislocation or rod breakage were not noted. Complications related to the pedicle screw placement were not observed either. All the patients were transfused with autologous blood except for two. In those patients two blood units for each of them were necessary in addition to the predonated three blood units. 4. Discussion Pedicle screws are used with increasing frequency for fixation in spinal fractures and instrumentation for degenerative spinal disorders. Their widespread use stems from the idea that pedicle screws provide better fixation and potential control of the coronal and sagittal planes than hooks and wires and require no reliance on distraction or compression. Screws achieve fixation by a means completely external to the spinal canal. Achievement of a solid spinal fusion continues to be the most important measure of success in spinal deformity surgery. Fixation for adolescent idiopathic scoliosis has continued

4?6

to evolve from cast fixation, to nonsegmental rods, to segmental sublaminar or spinous process wire fixation with nonsegmental hooks. The series by Suk et al12 and Hamill et al6 suggest the routine use of pedicle screws in the lumbar spine. The availability of pedicle screws begs the question of whether they become part of the standard instrumentation for adolescent idiopathic scoliosis. Evolution of prevalent instrumentation techniques for AIS has reflected not only the availability of these techniques but also the pursuit of a set of evolving goals. Solid fusion remains paramount, but enhanced correction of coronal and sagittal plane deformity has become a goal of spinal instrumentation. Better, more aggressive fixation, is also used in the name of instrumenting fewer levels, leaving potentially more mobility below the fusion mass. It is clear that segmental multihook contourable rod fixation has improved the attainment of these goals. Pedicle screw instrumentation of the lumbar curve may enhance the improvements achieved by multihook segmental fixation. Thus , it would seem clear that enhanced coronal plane correction can be attributed to the use of pedicle screws in the lumbar spine. Enhanced fixation is a presumed benefit of pedicle screws. Thus the theoretical benefit of enhanced fixation seems to be reflected in less loss of correction at follow-up which was observed in this series (average loss 1 °). Theoretically, enhanced fixation in the sagittal and coronal planes with pedicle screws would enable enhanced correction of rotational deformity in lumbar curves when pedicle screws are used at every pedicle and every level. The safety of pedicle screws has been questioned and discussed extensively. In theory, screws placed in the pedicle are safer than hooks or wires which must pass into the spinal canal. The most important features of the currently reported operative technique include application of forced translation to the apical vertebra into an overcorrected position. In addition, distinctive force is applied to the concave pedicle screw on the end vertebra. The current authors have not found pedicle screws in every vertebra necessary, nor have they found substantial compressive force along the rod on the convexity helpful. Measurement of the transverse pedicle width preoperatively is very essential when using traspendicular screw-rod systems for correction of idiopathic scoliosis. In the plain films these measurements are impossible. Weinstein et al13 and Whitecloud et al14 demonstrated that a roengenogram-based assessment using traditional anteroposterior and lateral views even for implanted pedicle screws resulted in an unacceptably high rate of false-positive and false-negative evaluations. As computed tomography scans have shown to provide a reliable assessment of pedicle screw placement. With the same method evaluation of the pedicles mainly of the apical and end vertebrae was carried out pre-operatively in this series. The results of this evaluation lead us to the use of paediatric screws (4,35mm) in certain thoracic levels. Pedicle screw instrumentation in scoliosis surgery is gaining in popularity because of its higher immediate rigidity , better correction and shorter fusion length. Several authors have reported on the neurologic hazards of pedicle screw instrumentation of the lumbar spine. Mulholland 10 attributed a greater risk of serious neural injury to thoracic pedicle screw placement than to lumbar pedicle screw instrumentation. Medial penetration is certainly the most feared screw misplacement because spinal canal encroachment may lead to spinal cord injury. Liljenqvist et al7 pointed out the direct contact between the pleural lining of the thoracic cavity and the inferolateral wall of the pedicle. A lateral screw penetration thus may endanger the lung or segmental vessels. Neither spinal cord injury nor segmental vessel trauma was noted in this.series.

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Predonation of autologous blood has been proved a safe method of intra and post operative blood transfusion in this series. All the disadvantages of homologous transfusion were avoided especially in the young population involved in spinal surgery. The correction of idiopathic curves with the use of segmental pedicle screw fixation system is a very effective method (correction>70%). Pedicle screws appear safe and are associated with a statistically greater curve correction, maintenance of correction, and improvement in the uninstrumented vertebral segments below the fusion. It seems that control of the three columns of the spine by the transpedicular screws offers better apical translation and coronal realignment. Despite of them, pedicle screw placement in the thoracic spine scoliosis surgery requires meticulous caution and considerable experience because of the limited applicability of the originally described landmarks of screw insertion to a scoliotic spine and because of the confined dimensions of the thoracic pedicles. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

14. 15.

Aebi M., Thalgoff J. S, Webb J.K. Scoliosis: Posterior correction and Stabilization. In AO ASIF principles in spine surgery p. 158 Springer Verlag 1998. Barr SJ, Schuette AM, Emans JB. Lumbar pedicle screws versus hooks. Spine 1997;22:1369-79 u66s N, Webb JK. Pedicle screw fixation in spinal disorders:a European view. Eur Spine J 1997;6:2-18. urown CA, Lenke LG, Bridwell KH, Geideman WM, Hasan SA, Blanke K. Complications of paediatric thoracolumbar and lumbar pedicle screws. Spine 1998;23:1566-71. Cortel Y, Dubousset J, Guillanmat M. New universal instrumentation in spinal surgery. Clin. Orthop 1988;229:10-23 Hamill CL, Lenke LG, Bridwell KH, Champan MP, Blanke K, Baldus C. The use of pedicle screw fixation to improve correction in the lumbar spine of patients with idiopathic scoliosis. Is it wanted? Spine 1996;21:1241-9. Liljenqvist U, Halm H, Link Th. Pedicle screw instrumentation of the thoracic spine in idiopathic scoliosis. Spine 1997;22:2239-45. Liljenqvist U. Vertebral morphology in idiopathic scoliosis. Didactic Session 1-7. Monney G. MD, Kaelin A. MD. Short posterior fusion for patients with thoracolumbar idiopathic scoliosis. Clin. Orthop. and Related Research, 364,32-39. Mulholland RC. Editorial:Pedic!e screw fixation in the spine. J. Bone Joint Surg [Br] 1994;76:517-9. Suk SI, Lee CK, Kim W, Chung Y, Park Y. Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis. Spine 1995;20:1399-1405. Suk SI, Lee CK, Min HI, Cho KH, Oh JH. Comparison of Cotrel-Dubousset pedicle screws and hooks in the treatment of idiopathic scoliosis. Int Orthop 1994;18:341-6. Weinstein JN, Spratt KF, Spengler D, Brick C, Reid S. Spinal pedicle fixation: Reliability and validity of roentgenogram-based assessment and surgical factors on successful screw placement. Spine 1998;13:1012-8. Whitecloud TS HI, Butler JC, Cohen JL, Candelora PD. Complications with variable spinal plating system. Spine 1989;14:472-6. Zindrick MR. Pedicle screw fixation. In Weinstein SL, ed. The Paediatric Spine: Principles and Practice. New York: Raven Press, 1994:1683-715.

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Spinal Surgery Procedure Discretization F. Verniest"23), D. Chopin (4), A-P.Godillon-Maquinghen <3), P. Drazetic ( 3 ) , C-E Aubin (l 2), F-X. Lepoutre(3> (l)

Res. Cent., S-Justine Hospital, 3175 Cote Ste-Catherine, H3T1C5, Montreal, Canada Biomed. Eng. Inst., Ecole Polytechnique de Montreal, Montreal H3C 3A7, Canada <3> LAMIH, Universite de Valenciennes, 59313 Valenciennes Cedex 9, France <4> Institut Calot, 62608 Berck sur Mer Cedex, France

I2>

Abstract: In the last decades, scientists developed analytic models of spinal surgery to assess surgical choices and instrumentation parameters. They noted the difficulty to represent the boundary conditions on their deterministic models and recognize the lack of knowledge in surgical procedures. This paper presents a formalization technique applied to spinal surgery to improve the formulation of biomechanical models. This technique consisted into two steps: knowledge extraction and knowledge representation. The protocol was established with an expert surgeon using Colorado2 instrumentation. Surgeon's knowledge acquisition has permitted to define eleven detailed independent data cards for the different steps of surgery like hook or screw insertion, rod installation, etc... The behaviour of the concerned elements on its neighbouring entity were specified using three matrices. The link between surgery and modelling becomes easier and permits to better define the boundary conditions on each entity during the simulation.

1.

Introduction

Over the past two decades, new advancing in surgical strategies to spinal deformities treatment and instrumentation systems have been realized [1]. To assess surgical choices and instrumentation parameters, scientists have developed 3D analytic models simulating surgical procedure [2-4] by simplifying it into two or three stages. Their representation of surgical acts is based on the general principles of the instrumentation technique, and is not personalized to the surgeon's experience and knowhow. Stokes et al. [5] note that the segmental instrumentation offers surgeons many variables and multistep maneuvers to adapt to individual patient's needs. But it conversely creates many unknowns for the biomechanical analyses (boundary conditions, number of stages, applied forces), and difficulties in validation of model predictions. They conclude that to help surgeon in the elaboration of his surgical planning, deterministic modeling of scoliosis surgery requires more information to formulate the models, better specifications of inputs and improved analysis tools. To this end, we propose to use techniques of artificial intelligence (AJ).The purpose of this paper is to present the mechanical formalization of surgical acts for scoliosis surgery from the know-how and knowledge of an expert surgeon using Colorado2 instrumentation. 2.

Methods

The surgeon expert technique is empirical and implies many conflicted variables and objectives that require an elaborate knowledge extraction. It is decomposed into two steps: knowledge extraction and knowledge representation.

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Knowledge Extraction It is based on IA techniques [6-10]. The first part of our protocol is to extract the expert's generalized knowledge. During interviews with the surgeon, a specific questionnaire related to specific cases is submitted. It permits to identify several variables that the surgeon is using during surgery and to evaluate their importance. To complete and refine the expert acquisition knowledge, the second part of the protocol was established during expert's activities. 20 surgical interventions of scoliosis were directly observed. These clinical cases were operated by the same expert surgeon. They were 18 females and 2 males. The mean age was 19 years. Each patient has idiopathic scoliosis pathology. All surgical procedures were applied by a posterior approach using Colorado2 instrumentation. Four stages were considered. Stage 1: Before beginning the surgery, the knowledge engineer with the surgeon analyse the clinical and geometrical data of the patient. The surgeon exposes his operative strategy and explains his choices. Stage 2: During surgery, the surgeon describes and explains each maneuver (implant insertion, deformation of rod, installation of rods,...). Stage 3: At the end of surgical intervention, the result of surgery is analyzed. Obscure points are discussed Stage 4: To validate expert's data collected during the other stages, and to finalize the knowledge extraction, it needs to confront the expert to his results. A few days later, using per-operative data, the specific strategy of the surgery is discussed and compared with operative strategy of similar cases operated by the same expert surgeon. Knowledge Representation The process is established from the decomposition of knowledge extraction analysis into two independents frames. The first steps consist to identify the different entities and surgical maneuvers of the surgery. Variables that appear clinically important to the surgeon and subjectively significant to the knowledge engineer, are classified and encoded. The scheme OBJECT-ATTRIBUTE-VALUE is affected to each variable and is inferred into IFTHEN rules[6]. This analysis permits to decompose the expert approach into standard leading facts. To each fact corresponds a card that contains a very detailed description of associated surgical act, geometrical and mechanical data of entities requested, representation analysis results [9]. The second frame consists to sequence the different surgical acts and associated variables to define the global procedure based on adapted constrained planning. Villeneuve et al. [11] propose to sequence the different tasks in tables, matrices or "deciding tree". Our choice is to organize different surgical acts through matrices. Each matrix specifies the behaviour of the concerned element on its neighbouring entity. 3.

Results

The different meeting between the expert surgeon and the knowledge engineer corresponded to eighty hours of interviews and analysis on two years. The expert's knowledge extraction permitted to define ten independent data cards : 1.- Patient Positioning ; 2.- Instrumented Zone Preparation ; 3.- Closed Laminar Hook Insertion ; 4.- Pedicular Hook Insertion ; 5.- Pedicle-Laminar clip ; 6.- Pedicular Screw Insertion ; 7.-Inter Pedicular Plate Positioning ; 8.- Fusion Preparation ; 9.- Rod Bending ; 10.- Clip insertion ; and one card corresponding to global surgical procedure: sequencing of surgical acts. To resume the sequence of activation and deactivation of joints or forces, the global surgical procedure was defined into three matrices: convex rod installation, concave rod

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installation, reduction by translation of the spine on the rods. Each matrix specifies the behaviour of the concerned element on its neighbouring entity. In application, the formalized data have been encoded into ADAMS software to formulate the mechanical model, using Poulin et al.[2] approach, to simulate the surgical procedure of a clinical case. The model is in respect with real surgical acts sequence and permitted to simulate independents actions like the translation of clip through rod, translation of clip to screw or hook, translation of nuts to mooring points, or rod adjustments. The figure 1 illustrates the configuration of the model at different steps.

Figure 1: Rods insertion on spine 4.

Discussion

The results of this study show the possibility to represent the link between the kinetics approach and the scoliosis surgery by the redaction of ten data cards describing the surgical actions and proposing associated biomechanical formalization and representation, and by three matrices sequencing all surgical actions. These results reflect a very detailed description and a more precise mechanical representation of different mechanical variables of scoliosis surgery as compared to precedent studies [2, 3]. The analysis of scoliosis surgery in our study is qualitative. But our method was allowed to identify most variables and steps of scoliosis surgery to improve the associated mechanical representation. In application a model using multi-body approach was generated and permitted to simulate all identified independent surgical acts of scoliosis surgery. Specific expert's information are not easily extracted because of the number and of the difficulty to analyze the interaction between them. To this end, we have proposed to use the IA techniques. This work was established about techniques of knowledge analysis, used in different domain like conception of aided process in fabrication or assembly to sequence machining operations [11] or in development of expert system flight monitor [12], and recently in scoliosis research [10]. The feasibility to use these techniques in scoliosis surgery modeling is now shown. However this protocol needs a large investment of the knowledge engineer and the surgeon. The small number of clinical cases and the planning of each associated surgery during the year is an important parameter to evaluate the expertise time. Quality of its analysis depends on many parameter: localization of protocol applications and meetings, personal investment of each actor, data treatment, number of clinical cases. The second stage of our protocol is in respect with the expectations defined by Fadier et al [13] who advise to realize the knowledge formalization from expert's work localization.

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This knowledge extraction is performed with only one expert surgeon, and the results are personalized to his know-how. We precise that a realization of a "universal" mechanical formalization of surgical acts could impose a muti-expert knowledge extraction that seems empirical in the scoliosis surgery domain using these formalization techniques. 5.

Conclusion

We have shown the feasibility to identify many surgical variables and parameters using the AI techniques. From these formalized data the biomechanical formulation of models is more complete and permits a great flexibility in the simulation of different surgical acts. The simulation of scoliosis surgery can now be personalized to patient's procedure and to the surgeon's know-how. The surgeon can now find in biomechanical model all surgical acts that they realized during surgery and can validate the modeling approach. 6. Acknowledgements CRNSG (Canada), FCAR (Canada), and MESR (France), Consulat de France (Quebec) References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

12.

13.

Chopin D., Advances in the Surgical Treatment of Scoliosis. European Instructional Course Lecture, 1997. 3: p. 173-180. Poulin F., et al., Modelisation Biomecanique de I'Instrumentation du rachis Scoliotique a I'aide de Mecanismes Flexibles: Etude de Faisabttite. Annales de Chirurgie, 1998. 52: p. 761-767. Aubin C-E., Finite Element Analysis for the Biomechanical Study of Scoliosis. Spine, 2000. 14(2): p. 489-504. Verniest F., et al., Biomechanical Simulation of Colorado Instrumentation of the Scoliotic Spine: Preliminary Results, in IRSSD 2000. 2000. Stokes I.A.F., et al., Biomechanical Simulations for Planning of Scoliosis Surgery, in Research into Spinal Deformities 2,1.A.F.S. Ed., Editor. 1999, IDS Press, p. 343-350. Olson J. R. and Rueter H. H., Extracting Expertise from Experts: Methods for Knowledge Acquisition. Expert Systems, 1987.4: p. 152-167. Boy G., Acquisition des connaissances, in Assistance a I'operateur : une approche de I'intelligence artiflcielle, Teknea, Editor. 1988. Benkirane M., et al. Aspects de la Psychologic Cognitive dans I'acquisition des connaissances. in Actes de la 2eme Conference Europeenne et les Applications de VIA en milieu industriel et de service. 1990. Anselmetti A. and Villeneuve F., Computer Aided Process Planning : two ways for inclunding a user's know-how. Manufacturing Systems, 1992.21: p. 167-172. Chusseau S., Systeme d'aide a la decision pre-operatoire en chimrgie orthopedique de la scoliose, in These en Automatique Industrielle et Humaine. 1999, Univerist£ de Valenciennes et du Hainaut Cambr&is: Valenciennes. Villeneuve F. and Sabourin L. Machining Features, Production Rules and Constraint Programming, Keys for a Capp System, in Proceedings of the 2nd International Conference on Industrial Automation. 1995. Disbrow J.D., Duke E.L., and Regenie V.A. Development of Knowledge Acquisition Tool for an Expert System Fligth Status Monitor, Technical Memorandum, in AIAA 24th Aerospace Sciences Meeting. 1986. Reno, Nevada. Fadier E., et al., Valorisation du Retour d'Experience - dossier Retour d'experience. Performances Humaines et Techniques, 1994. 69: p. 34-37.

Th.B. Gri\as(Ed.t Research into Spinal Deformities 4 IDS Press. 2<><>2

Surgical treatment of scoliosis in myelomeningocele Patrizio Parisini, Tiziana Greggi, Mario Di Silvestre, Federico Giardina, Georgios Bakaloudis Spine Surgery Dept., Rizzoli Orthopedic Institute, Via Pupilli, 1, 40136 Bologna, Italy

Abstract The high incidence and rapid progression of scoliosis in myelomeningocele make it one of the most disabling aspects of such disease. The choice of the surgical procedure to treat scoliosis in myelomeningocele is related to the peculiar features of this deformity. The purpose of this study is to review the results obtained by means of various surgical techniques and verify if posterior fusion with pedicle screws can improve results as compared to the single posterior approach. Patients were classified into three groups defined by treatment approach. The single posterior approach following either the Harrington or the Harrington-Luque technique yielded the least satisfactory results. The two-stage anterior-posterior spinal fusion provided good correction and stability. Correction and instrumented fusion through a single posterior approach with segmental fixation by means of pedicle screws proved to be valid and reliable, even when severe deformities had to be corrected and fused. In these latter cases pelvic fixation using ilio-sacral plates also made it possible to correct and stabilize pelvic obliquity.

1. Introduction Scoliosis is one of the most frequently (50-80%) encountered problems in myelomeningocele patients [1,2]. Since it progresses rapidly, very severe curves may develop early (Figure 1). Pelvic obliquity and deviations from the physiologic curves in the sagittal plane are the peculiar features. Trunk can really collapse on account of the thoraco-lumbar hyperkyphosis, or very severe lumbar hyperlordosis and pelvic obliquity can lead to lateral trunk shift. When the spinal deformity worsens, patients who cannot deambulate any more (or never could) may develop an imbalanced sitting position. Treatment with braces cannot generally decrease the high rate of progression of these deformities. Surgery therefore becomes mandatory to achieve, and above all maintain, adequate spinal balance and allow patients to tolerate pelvic obliquity. In most of the cases the aim of correction and fusion is to achieve at least a wellbalanced sitting position and preserve respiratory function [3]. Surgery for scoliosis in myelomeningocele is very demanding and often associated with complications [2,4]. The purpose of this study is to review and compare results obtained by means of various techniques. Above all, the present authors aim to verify if pedicle screws can improve the single posterior approach in terms of outcomes.

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Figure la. SA, A 1 yr-old boy affected with rapid evolving scoliosis secondary to myelomeningocele; Ib. at the age of 6 yrs ; Ic. at the age of 11 yrs ; Id. at the age of 14 yrs.

2. Materials and Methods A review of 33 patients surgically treated at our Department for scoliosis in myelomeningocele was undertaken. Subjects were divided into 3 groups of 10 fundamentally based on the different surgical approach used. Only three cases were excluded from the study since their follow-up was too short. Consequently, the study included 30 cases operated on from 1974 to 1997. There were 22 male and 8 female patients, aged 11.5 yrs on average (range, 2 to 22). The first group was made up of 7 male and 3 female patients, aged 12.6 yrs on average (range, 2 to 22). They were treated from 1974 to 1978 by single posterior approach using the Harrington technique in 3 cases and the same technique with sublaminar wiring fixation according to Luque in the remaining 7 cases. Distal fusion was extended to the sacrum in all cases. The second group was made up of 2 female and 8 male patients aged 11 yrs on average (range, 7 to 14 yrs). All the subjects received treatment during the 80s by combined anterior and posterior approach. The posterior approach was performed following the HarringtonLuque technique with fusion extended to SI in 4 cases, and following the Luque technique with Galveston fixation extended to SI in the remaining 6. Zielke and Dwyer instrumentation were used for the anterior procedure in 1 and 9 cases, respectively. Mean time interval between the anterior and posterior approach was 1 month. Treatment in one session was performed only in one case in which the double approach was carried out. The third group was made up of 3 female and 7 male patients always aged 11 yrs on average (range, 8 to 14 yrs). They were treated from 1995 to 1997 via a single posterior approach using segmental instrumentation with lumbar pedicular fixation, associated with laminar and pedicular hook fixation and sublaminar wiring in the thoracic region. Fusion was extended to L5 in the 2 cases who had good walking autonomy, whereas the remaining 8 cases with severe pelvic obliquity and complete paraplegia were fused to the sacrum and underwent pelvic fixation with ilio-sacral plates.

P. Parisini et ui / .Snn>icdl Treatment <>1 Scoliosts in Mveloineningoceli'

Figure 2a. Harrington instrumentation; 2b. Harrington-Luque instrumentation posteriorly and Dwyer system anteriorly ; 2c. Posterior pedicular instrumentation with ilio-sacral plates.

3. Results Results obtained in the various groups were assessed and compared. At a mean followup of 15 years, a mean correction of scoliosis of 17%, no correction of hyperlordosis, and a modest correction of hyperkyphosis of 12% were observed in the historical group (patients treated only by posterior approach using the Harrington or Harrington-Luque technique) (Table 1).

FIRST GROUP SCOUOSIS KYPHOSIS PELVIC OBLIQUITY

Preop" 88 51 16

Postop0 65 31 7

Final Follow-up0 Improvement 17 73 57 12 50 8

Table 1 Ten complications were encountered (100%): 3 pseudarthroses, 4 dislodged instrumentation and 3 deep infections. Reinterventions were 7 (70%). Three cases with deep wound infection observed postoperatively, required wound revision and positioning of drainages. The remaining 4 reinterventions were necessary to repair a pseudarthrosis (2 cases), fix a dislodged hook (1 case) and adjust the instrumentation rods that protruded under the skin proximally. At an average follow-up of 11 years the following mean values were registered for the second group (patients treated by double surgical approach): correction of scoliosis of 57%,

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correction of hyperkyphosis of 53%, correction of pelvic obliquity of 43%, and correction of hyperlordosis of 30% (Table 2). SECOND GROUP SCOLIOSIS KYPHOSIS PELVIC OBLIQUITY LORDOSIS

Preop0 101 93 37 95

Postop0 32 36 19 55

Follow-up0 43 44 21 67

Final lmprovement% 57 53 43 30

Table 2

The incidence of complications was equal to 70%: 2 pseudarthroses, 3 dislodged instrumentation and 2 deep infections. The total number of reinterventions in this group was 5 (50%). Three were carried out in the same patient: the onset of pseudarthrosis with loss of correction and recurrent severe pelvic obliquity made it necessary to perform a first revision of the posterior arthrodesis with removal of the Harrington-Luque instrumentation. Progressive traction was then exerted, and the Harrington-Luque system with compressor was subsequently applied surgically. Afterwards, two years after the first surgery, a deep infection with cutaneous fistula required a posterior surgical revision with partial removal of instrumentation and cutaneous plastic surgery. Another reintervention was carried out in a subject who showed severe worsening of the kyphosis above the fusion level that had been extended proximally. Finally, the remaining reintervention was performed in a case who had a distal subcutaneous protrusion secondary to dislodged posterior instrumentation with no loss of correction: the patient required posterior instrumentation removal. At an average follow-up of 3 years the following mean values were registered in the third group: correction of scoliosis of 47%, correction of hyperlordosis of 70%, correction of hyperkyphosis of 50%, and correction of pelvic obliquity of 40% (Table 3).

THIRD GROUP SCOLIOSIS KYPHOSIS PELVIC OBLIQUITY LORDOSIS

Preop0

85 71 25 117

Postop0 40 32 13 26

Final Follow-up0 lmprovement% 45 47 36 50 15 40 28 76

Table 3

Statistical analysis of the results (ANOVA) revealed a significant improvement (p<0.05) in lordosis of the 3rd group of patients as compared to the 2nd group. Three complications were encountered (30%): a cerebrospinal fluid fistula observed in the immediate postoperative period, a deep infection seen about 1 year after surgery with pseudarthrosis in the lumbosacral region and loss of correction, and a mechanical complication. These cases required a reintervention: surgical revision with repair of dural breach, surgical cleaning with instrumentation removal and fusion revision, and refusion. 4. Discussion Surgical treatment for scoliosis in myelomeningocele is well-known to be associated with a high rate of complications. Percentages often exceeding 50% are documented in the

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literature: Luque has reported a 61% incidence [5], Ward a 58% incidence [6], Geiger a 52.2% incidence [2] and Widmann a 70% incidence [7]. The surgical technique can obviously influence the amount of correction, the problems related to fusion stability, the onset of pseudarthroses and infections. The first group treated by means of a single posterior approach experienced the lowest correction of scoliosis and the highest loss of correction at follow-up (Table 1). When using the Harrington technique, the present authors observed a 40% incidence of dislodged posterior instrumentation, an equivalent percentage in terms of loss of correction and a 30% rate of pseudarthrosis. Mazur [8] has reported a 20% incidence of dislodged posterior instrumentation and a 33% incidence of pseudarthrosis using the same technique. Without any doubt the current findings cannot be compared to the data available in the literature on account of the low number of patients reviewed. However, the present authors soon abandoned the use of such a technique in the treatment of these deformities for the other procedures described in this paper, as did other Authors [2]. The second group presented a lower - but always very high - incidence of complications (70%), and better results at follow-up. When the double approach was used, the rate of dislodged posterior instrumentation was lower (30%) than in the first group. Such finding is consistent with the previous observations by Geiger [2] who has observed a 28% incidence. Results in terms of correction of the deformity at follow-up also showed evidence of stability (Table 2). The third group was made up of those cases treated only posteriorly by segmental and pedicular fixation and pelvic anchorage by ilio-sacral plates. The percentage correction of scoliosis was slightly lower than that observed when the double approach was used, whereas correction of hyperkyphosis, hyperlordosis and pelvic obliquity improved (Table 3). The choice of the surgical approach and technique is related not only to the type of instrumentation to be applied, but also and above all to the type of deformity and specific patient characteristics. If on the one hand the single anterior approach can avoid or minimize the risk of cutaneous problems in the lumbosacral tract, on the other hand it may be very risky in the myelomeningocele patients whose respiratory function is severely compromised. Moreover, according to some authors [9], it may be associated with the complication of hemodynamic instability. From a mechanical point of view, the anterior instrumentation alone is not sufficient to prevent progression of severe hyperlordosis and pelvic obliquity [4,10]. Fusion achieved by anterior approach, even if instrumented, can rarely be reliable from a mechanical point of view when managing scoliosis in myelomeningocele. In any case, it cannot be the treatment of choice when scoliosis exceeds 80° [11]. Regarding the upper level of fusion, Wild [12] has suggested leaving the lumbosacral tract uninstrumented and asserted that pelvic obliquity in scoliosis due to myelomeningocele is spontaneously corrected when the scoliotic deformity is adequately addressed with instrumented fusion without inclusion of the sacrum. In the current authors' opinion, the probability of such a phenomenon to occur is low in patients with a thoracic level of paralysis [13]. Although posterior spinal fusion with segmental instrumentation ensures a better incidence of fusion than with the Harrington rod, it does not match the fusion rates that can be obtained with combined anterior and posterior surgery [14,15]. Pedicle screw instrumentation is uniquely suited to the deficient spine in myelomeningocele [16]. Compared with the historical group, these devices have proven capable of correction of both scoliotic and kyphotic deformities. The reduction of pelvic obliquity, which is fundamental for the sitting ability, significantly improved in the third group as compared to the second one. A major issue to be addressed for each patient is if the higher fusion rates justify the added morbidity of an anterior procedure.

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5. Conclusions The two-stage anterior-posterior spinal fusion provides better and immediately stable correction in sagittal plane, in addition to good correction of pelvic obliquity. However, in the present authors' opinion, the single posterior approach with segmental fixation by very stable anchoring devices, such as pedicle screws, can be the treatment of choice for the rapidly progressive deformities when the patient can still walk with some autonomy. Pelvic anchorage by ilio-sacral plates ensures stable fixation. If associated with pedicular fixation at least of the lumbar tract, it also provides good posterior correction of the severest deformities, in spite of the risks related to the cutaneous problems at the site of the pre-existing myelomeningocele. The posterior approach allows spine surgeons to avoid the anterior approach when the respiratory function is compromised.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

E. B. Mueller et al., Progression of Scoliosis in Children with Myelomeningocele, Spine 19 (1994) 147150. F. Geiger et al., Complications of Scoliosis Surgery in Children with Myelomeningocele, Eur Spine J 8 (1999) 22-26. C. Carstens et al., Effect of Scoliosis Surgery in Pulmonary Function in Patients with Myelomeningocele, J Pediatr Orthop 11 (1991) 459-464. A. Stark and H. Saraste, Anterior Fusion Insufficient for Scoliosis in Myelomeningocele, Acta Orthop Scand 64 (1993) 22-24. E. R. Luque, Paralytic Scoliosis in Growing Children, Clin Orthop 163 (1982) 202. W. T. Ward et al., Surgical Correction of Myelomeningocele Scoliosis: a Critical Appraisal of Various Spinal Instrumentation Systems, J Pediatr Orthop 9 (1989) 262-268. R. F. Widmann et al., Lumbosacral Fusion in Children and Adolescents Using the Modified Sacral Bar Technique, Clin Orthop 364 (1999) 85-91. J. Mazur et al., Efficacy of Surgical Management for Scoliosis in Myelomeningocele: Correction of Deformity and Alteration of Functional Status, J Pediatr Orthop 6 (1986) 568-575. L. A. Karol et al., F. Safavi, Hemodynamic Instability of Myelomeningocle Patients during Anterior Spinal Surgery, Developmental Medicine and Child Neurology 35 (1993) 258-274. C. G. Hopf and P. Eysel, One-stage versus Two-stage Spinal Fusion in Neuromuscular Scoliosis, J Pediatr Orthop Part B 9 (2000) 234-243. P. D. Sponseller et al., Anterior Only Fusion for Scoliosis in Patients with Myelomeningocele, Clin Orthop 364(1999)117-124. A. Wild et al., Is Sacral Instrumentation Mandatory to Address Pelvic Obliquity in Neuromuscular Thoracolumbar Scoliosis Due to Myelomeningocele?, Spine 26 (2001) 325-329. D. Parsch et al., Surgical Management of Paralytic Scoliosis in Myelomeningocele, J Pediatr Orthop Part B 10(2001)10-17. D. M. Banit et al., Posterior Spinal Fusion in Paralytic Scoliosis and Myelomeningocele, J Pediatr Orthop 21(2001)117-125. J. V. Banta, Combined Anterior and Posterior Fusion for Spinal Deformity in Myelomeningocele Spine, Spine 15 (1990) 946-952. W.B. Rodgers et al., Spinal Deformity in Myelodysplasia. Correction With Posterior Pedicle Screw Instrumentation, Spine 22 (1997) 2435-2443.

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Use of a Transpedicular Drill Guide for Pedicle Screw Insertion in the Thoracic Spine Jean-Marc Mac-Thiong112, Hubert Labelle1*2, Marcel Rooze3, Veronique Feipel3 and Carl-Eric Aubin1'4 7 - Department of Surgery, University of Montreal, PO Box 6128, Station Centreville, Montreal (Quebec), Canada H3C 3J7 2 - Research Center, Sainte-Justine Mother-Child University Hospital, 3175 CoteSainte-Catherine, Montreal (Quebec), Canada H3T1C5 3 - Laboratory for Functional Anatomy and for Anatomy and Embryology, University of Brussels, PO Box 619, 808 route de Lennik, 1070 Brussels, Belgium 4 - Department of Mechanical Engineering, Ecole Poly technique, PO Box 6079, Station Centre-ville, Montreal (Quebec), Canada H3C 3A 7 Abstract. A transpedicular drill guide (TOG) was designed to assist in the safe placement of pedicle screws in the thoracic spine. In a preliminary study, pilot holes were drilled into the pedicles (Tl to T12) of eight anatomical models in order to compare the conventional anatomical technique to the TDG. Visual inspection of the drilled pedicles was performed. Subsequently in a cadaveric study, pilot holes were made using the TDG in the thoracic spine (Tl to Tl 1) of one human cadaver before inserting 4.5 mm diameter screws. CT scan followed by visual inspection of the cadaveric spine was performed to evaluate the position of the screws. With the anatomical models, 19 of 96 (19.8%) holes drilled using the TDG and 64 of 96 (66.7%) holes drilled using the anatomical technique violated the pedicle wall (p<0.001). The TDG reduced the rate of medial perforation. Ninety-nine percent of the pilot holes made with the TDG were within 2 mm from the pedicle wall compared to 79.2% for the anatomical technique. In the cadaveric study, one of the 22 (4.5%) screws violated the medial wall of the right Tl pedicle by less than 1 mm. No screw penetrated the anterior vertebral cortex, nor the lateral, superior or inferior pedicle wall. The TDG is easy to use and can decrease the incidence of misplaced thoracic pedicle screws. The TDG could be used alone as an alternative to navigation systems in certain applications or with fluoroscopy during thoracic pedicle screw placement, especially for training surgeons.

1. Introduction The use of pedicle screws is gaining increasing popularity for instrumentation of the thoracic spine. Biomechanically, thoracic pedicle screws have been shown to offer more strength and stiffness than pedicle hooks [1]. Potential applications of thoracic pedicle screw instrumentation include fracture, segmental instability, hyperkyphosis, scoliosis, infection and tumor [2-5]. However, insertion of pedicle screws in the thoracic spine is technically difficult and may lead to significant complications. Placement of thoracic pedicle screws based on anatomical knowledge and/or fluoroscopy is variable and can give a high failure rate [2-7]. This is why some surgeons use computer-assisted systems that have proved to be safe and accurate [2,8,9]. However, these systems are expensive, require pre-operative CT scans and

J.-M. Mac-Thiong el al. / Use of a Transpedicular Drill Guide

intra-operative registration, involve a marked learning curve and are not widely available. In search of an intermediate solution between the conventional anatomical and computer-assisted techniques, we designed a transpedicular drill guide (TDG) to assist in the safe placement of pedicle screws in the thoracic spine. The purpose of the current study is to describe the TDG and to assess its accuracy before clinical use. 2. Materials and Methods The TDG (patent pending) is composed of a sublaminar pedicle finder and a drill sleeve that can be moved along an arc of circle (Figure 1) The use of the TDG for pilot hole preparation is summarized in Figure 2. The insertion point was located at the intersection between the superior border of the transverse process and the lateral twothirds of the superior facet [6]. According to reported morphometric data [10], the sagittal drilling angle was kept between 15° and 20° for all thoracic levels. The angle of drilling in the transverse plane is set automatically by the TDG. It is always formed by the line joining the insertion point and the center of the pedicle section intersected by the pedicle finder (as viewed from the transverse plane). Image intensification is not required and was not used prior to or during pilot hole preparation in the present study, but may be used as an additional safety procedure in difficult situations.

Figure 1: Transpedicular drill guide for pedicle screw insertion in the thoracic spine.

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Figure 2: Steps required for pilot hole preparation with the TDG. A) Engage the pedicle finder under the lamina to firmly anchor the TDG to the pedicle (a partial laminectomy may be performed to facilitate this step). B) Adjust the TDG to obtain the desired insertion point for drilling. C) Adjust the TDG depending on the desired drilling angle in the sagittal plane. D) Drill the pilot hole.

In a preliminary validation of the TDG, eight anatomical models of the spine (Sawbones, Pacific Research Laboratories, USA) were placed into a commercial holder (Sawbones) designed for posterior spine approach. The spines were covered with opaque granules in order to reproduce as closely as possible the visibility of the spine during a standard posterior exposure. A total of 192 pilot holes were drilled from Tl to T12 vertebrae: 96 with the conventional anatomical technique and 96 with the TDG. For the conventional anatomical technique, the entrance point was also located at the intersection between the superior border of the transverse process and the lateral two-thirds of the superior facet [6]. Pilot holes were drilled using a powered 2.9 mm drill bit for both techniques without the aid of image intensification. After drilling the pilot holes, the vertebrae were disarticulated. A Kirschner wire (2.9 mm) was then inserted into each pilot hole. In the presence of a pedicle violation, the maximum distance between the pedicle wall and the surface of the Kirschner wire was measured with a digital caliper. The success rates for the conventional and TDG techniques were compared using a %2 (Chi-square) test and a level of significance set at 0.05. The cadaveric study was performed at the Laboratory for Functional Anatomy of the University of Brussels with one elderly female cadaver showing no signs of spinal deformity. The cadaver was positioned prone and the thoracic spine was exposed as for a posterior spine surgery. Pilot holes (total of 22) were made bilaterally from Tl to Tl 1 using the TDG and a 3.2 mm straight probe. No pilot holes were drilled into the T12 vertebra according to the results of the preliminary study (see Discussion section). AO cortical screws of 4.5 mm diameter (38 mm length) were inserted into all pilot holes. Pedicle instrumentation was performed by a senior

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orthopedic surgeon (H.L.), well trained in the routine use of pedicle screws in the thoracolumbar and lumbar areas, but with a more limited experience in the use of pedicle screws above T10. Following placement of the pedicle screws, spiral CT scan (CT Twin Flash, Elscint, Israel) were obtained for each specimen. Screw position was verified on overlapping CT scan slices (increment of 1.5 mm, thickness of 2.7 mm). After the CT scan, the spine was harvested and the posterior vertebral arch was removed in order to confirm by visual inspection any medial, inferior or superior pedicle wall violation. The rib head was not removed for visual examination of the lateral pedicle wall. 3. Results In the preliminary study, the overall success rate was statistically different between the anatomical technique and the TDG (p<0.001). With the conventional technique, 64 (66.7%) of the 96 pilot holes violated the pedicle wall ( Table I). Fifty holes (52.1%) were misplaced medially, 12 (12.5%) laterally and two (2.1%) inferiorly. Seventy-six holes (79.2%) were within 2 mm of the pedicle wall. Using the TDG in the preliminary study, 19 (19.8%) of the 96 pilot holes perforated the pedicle wall ( Table I). The misplaced holes especially occurred at T4, T5, T6 and T12. Eight holes (8.3%) were misplaced medially and 11 (11.5%) laterally. Ninety-five of 96 holes (99.0%) were within 2 mm of the pedicle wall. One hole perforated the medial wall of the T12 right pedicle by 4.7 mm. In the cadaveric study, only one (4.5%) of the 22 screws violated the medial wall of the right pedicle of Tl vertebra ( Table I). The perforation was within 1 mm of the pedicle wall, with only part of the screw threads outside the pedicle. No screw penetrated the anterior vertebral cortex, nor the lateral, superior or inferior pedicle wall. No evidence of injury to the dura mater and spinal cord was found during the visual examination made after removing the posterior vertebral arch. Table I: Occurrence of lateral (L), medial (M) and inferior (I) pedicle wall perforations for all vertebral levels

Vertebral level

Tl T2 T3 T4 T5 T6 T7 T8 T9 T10 Til T12 Perforation rate

Preliminary study Anatomical TDG < 2 mm > 2 mm < 2 mm > 2 mm — — 1L, 1M 1L — — 1L, 1M 2L 2L, 1M 1L 1L — — 3L,3M 3L — 1L.3M 1M 3L, 1M — 3M 4M 1L.2M — 5M 1M 1L, 1M — 5M 2M 2L — 4M, 11 1M — — 3M 1M 1M —

3M

3M

2M, 11 3M 66.7% (64 of 96)

— — 2M 1M 19.8% (19 of 96)

Cadaveric study

TDG < 1 mm

1M — — — — — — — — — — — 4.5% (1 of 22)

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4. Discussion The TDG was found to be simple and easy to use. It gave additional control and stability to the drilling process. Apart from the simple adjustments to the TDG, no modification to the surgical technique was required. The correct use of the TDG would be particularly easy for surgeons already familiar with pedicle hook systems, since it is mainly based on an adequate anchoring of the sublaminar pedicle finder to the pedicle. The preliminary study showed a statistically significant advantage of the TDG over the conventional anatomical technique (p<0.001). The results for the TDG were similar to those obtained by Amiot et al. [11] with a computer-assisted system. Using the same type of anatomical models and the same drill bit diameter, they reported a "safe" rate (pedicle violation < 2 mm) of 91.1% for vertebrae T4 to T12 using a computer-assisted technique, which is similar to the "safe" rate obtained with the TDG (97.2%) for T4 to T12. Amiot et al. [2] obtained a better success rate for in vivo applications using the same system ("safe" rate of 100%). This suggests that the error margin was not sufficient to drill a pilot hole without perforating the pedicle wall in some anatomical models, especially at T4 to T6 levels for which the diameter was sometimes smaller than 3.5 mm while the drill bit diameter was 2.9 mm in the preliminary study. The higher success rate in the cadaveric study using a 3.1 mm diameter probe and 4.5 mm screws indicates that the transverse diameter of the pedicles was larger for the cadavers. Furthermore, the anatomical models were made of brittle urethane foam that was more prone to pedicle fracture than human bone. The high failure rate at T12 level in the preliminary study was caused by an improper use of the pedicle finder. The more lateral pedicles at this level are transitional between thoracic and lumbar configurations, making it difficult to use the TDG unless an extensive laminectomy is performed. Based on these results, we do not recommend the use of the TDG at T12. Accordingly, we did not use the TDG for T12 in the cadaveric study. Some misplaced holes with the TDG were also possibly due to the drill bit that had been bent and manually corrected several times during the preliminary study. This drill bit was extended by welding a steel rod of the same diameter. This explains why we used a full length stainless steel probe in the second part of the study. In the cadaveric study, adequate anchoring of the pedicle finder to the pedicle was sometimes difficult to assess by the surgeon because the spine was much more stiffer and less mobile than normally, due to the effect of the preservation solution on the soft tissues. This may perhaps explain the misplaced screw. Correct engagement of the pedicle finder is easier in live patients with normal vertebral mobility. The overall pedicle violation rate (4.5%) was in the same range as those reported with computer-assisted pedicle screw insertion in the thoracic spine. Kim et al, [8] inserted 120 pedicle screws from Tl to T12 on five cadavers using a computerassisted technique. They obtained an overall pedicle violation rate of 19.2%, with 65.0% of the perforations being medial. From their case series, Youkilis et al. [9] reported 9.8% cortical violations for 183 image-guided thoracic pedicle screws (Tl to Til), while Amiot et al. [2] had only one misplaced screw (1.4%) for 74 screws inserted from Tl to Tl 1. As opposed to computer-assisted systems, the TDG is more affordable, is simpler to use and does not require pre-operative CT scan imaging. Furthermore, computer-assisted techniques require additional staff and equipment in the operating room and are associated with a considerable learning curve.

J.-M. Mac-Thiong et al. / Use of a Transpedicular Drill Guide

The transverse screw angle is a critical issue for safe insertion of pedicle screws in the thoracic spine [3]. Very slight discrepancy between the pedicle and screw medio-lateral inclinations can lead to pedicle wall perforation. The main advantage of the TDG is that it automatically sets the optimal transverse angle for pilot hole preparation. This is why the TDG especially decreased the incidence and extent of medial perforations, which is the most feared event because of the risk of spinal cord injury. Only one of 22 screws (4.5%) perforated the medial wall. Although the distance between the pedicle and the dural sac is absent or minimal [12], a minor perforation of the medial pedicle wall such as the one found in the current study is not at risk of causing neurological complications. It has been shown that a medial perforation of up to 4 mm does not create any neurological compromise [13]. The TDG is non invasive, easy to use and can decrease the incidence of misplaced thoracic pedicle screws from Tl to Til. Its accuracy is significantly superior to the anatomical-based technique [2-7] and similar to computer-assisted techniques [2,8,9]. It could be used as an alternative to navigation systems for certain applications, especially for training surgeons. The TDG could also be combined with fluoroscopy to increase its clinical accuracy.

References 1. 2. 3. 4. 5 6. 7. 8. 9. 10. 11. 12. 13

UR Liljenqvist et al., Pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine, Acta Orthop Belg 67 (2001) 157-163. LP Amiot et al., Comparative results between conventional and computer-assisted pedicle screw installation in the thoracic, lumbar, and sacral spine, Spine 25 (2000) 606-614. PJ Belmont Jr et al., In vivo accuracy of thoracic pedicle screws, Spine 26 (2001) 2340-2346. UR Liljenqvist et al., Pedicle screw instrumentation of the thoracic spine in idiopathic scoliosis, Spine 22 (1997) 2239-2245. S-I Suk et al., Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis, Spine 20 (1995) 1399-1405. G Cinotti et al., Pedicle instrumentation in the thoracic spine. A morphometric and cadaveric study for placement of screws, Spine 24 (1999) 114-119. AR Vaccaro et al., Placement of pedicle screws in the thoracic spine. Part II: an anatomical and radiographic assessment. J Bone Joint Surg Am 77 (1995) 1200-1206. KD Kim et al., Computer-assisted thoracic pedicle screw placement: an in vitro feasibility study, Spine 26 (2001) 360-364. AS Youkilis et al., Stereotactic navigation for placement of pedicle screws in the thoracic spine, Neurosurgery 48 (2001) 771-778. MR Zindrick et al., Analysis of the morphometric characteristics of the thoracic and lumbar pedicles, Spine 12 (1987) 160-166. LP Amiot et al., In vitro evaluation of computer-assisted pedicle screw system [in French], Ann Chir 51(1997) 854-860. HC Ugur et al., Thoracic pedicle: surgical anatomic evaluation and relations, J Spinal Disord 14 (2001) 39-45. SD Gertzbein and SE Robbins, Accuracy of pedicular screw placement in vivo. Spine 15 (1990) 11-14.

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Surgical Management of a Congenital Kyphotic Deformity in an Adolescent A. Christodoulou, A. Ploumis, J. Terzidis, K. Tapsis, P. Hantzidis Orthopaedic Department of Hippokration General Hospital ofThessaloniki Abstract This is a case of an adolescent with kyphoscoliosis due to congenital partially segmented vertebrae T12, LI, L2 who was treated operatively by a back-front-back, one stage operation. A 16 year old patient neurologically intact with a rounded gibbous in the lower thoracic region and a mild scoliotic element had no other congenital anomaly. His kyphotic deformity was 85° measured with the Cobb method. Preoperatively, a CT and MRI scan of the spine was performed and a three-level anterolateral failure of segmentation in the thoracic spine was diagnosed without spinal dysraphism. The operation lasted 8 hours and the Moss-Miami anterior and posterior fixation systems were used for fusion from T10 to T4. It included initially posterior approach for transpendicular screw insertion, wedge resection of the posterior elemens followed by anterior approach (thoracotomy), osteotomy of the defected vertebrae, anterior correction and fusion TI1 to LI and final correction with rod placement posteriorly. The wake-up test was performed twice. The follow-up was 3 years. The postoperative correction of the kyphosis was 45% (42°) and there was practically no loss of correction in the last follow-up. No complications were observed. Detailed preoperative assessment of the patients with congenital deformities is essential in order to establish the correct diagnosis and choose the proper treatment. Substantial kyphotic deformities require combined antero-posterior procedures.

1. Introduction Sagittal plane spinal deformities are rarely found compared to scoliotic ones. Nevertheless, they also contribute to poor cosmetic appearance, low functional ability, fatigue pain from neck and hip extensors and degenerative tendency of the adjacent spinal units. Congenital kyphosis is divided into three types, according to the basic defect: failure of formation, failure of segmentation, and mixed varieties1. Failure of segmentation produces a kyphotic deformity in one or multiple levels. When the defect is strictly anterior, a pure kyphotic deformity is appeared. But when the defect is anterolateral, then a kyphoscliosis will result. A one stage three procedure surgical correction and the postoperative followup of a congenital kyphoscoliosis in a 16 year-old patient is presented. 2. Case report A 16 year-old adolescent visited the spine unit clinics complaining for a gibbous deformity of his lower thoracic spine and pain due to compensatory lumbar hyperlordosis ( F i e . I). The deformity was known since childhood hut became more

A. Christodoulou et at. /Surgical Management of a Congenital Kyphotic Deformity

prominent the last two years. He used Milwakee brace intermittently but the deformity worsened. Clinical examination

Fig.l Patient with a rounded gibbous in the. lower thnrar.ir region

F|g 2 Preoperative radiograph

revealed a rounded gibbous, manifested when bending forward. The bending test was negative for rib prominence. There were no neurologic signs or other congenital defects. Plain radiographs (Fig.2) showed a block vertebrae consisting of T12, LI and L2 vertebral bodies without any rotation of the affected vertebrae. Using the Cobb method an 85° kyphotic and 15 ° scoliotic angle was estimated. Stress profile radiographs with flexion and extension of the spine did not alter the magnitude of the deformity at the affected level. CT and MRJ confirmed the diagnosis of anterolateral failure of segmentation of T12, LI, L2 vertebrae and intraspinal anomalies were excluded. The patient was admitted in the spinal unit of the Orthopaedic Department and the necessary preoperative exams including pulmonary functional tests were conducted. A same-day surgery was undertaken and the procedure took place under fluoroscopy. Under controlled hypotensive anesthesia along with a cell saver, a midline posterior incision in the thoracolumbar region was made. The spinous, transverse and articular processes and lamina of the T12 and LI were resected in the shape of a chevron. Transpendicular screws of 5mm were inserted from T10 through L4. Next, a left thoracotomy was performed, and anterior longitudinal ligament transection and excisional osteotomy of T12 and L1 vertebrae were carried out. The neural canal was under direct vision. A cylindrical titanium cage, filled with autologous rib and vertebral graft, was placed after distraction and correction of the kyphosis and supported the anterior column. An anterolateral lg rod with two screws provided extra stability. A chest. drain was ' .. ost°Peratlve . . _. . . cosmetic appearance inserted pnor to wound closure. Final correction with posterior rods, properly contoured to reduce the mild scoliotic curve, and compression of the transpendicular screws leaded to improved result. The wake-up test was performed Fig. 3 Postoperative radiograph at the last follow up

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twice during operation and the patient responded appropriately. The total operative time was eight hours. The Moss-Miami fixation systems were used. Postoperatively, the patient spent approximately 24 hours in the intensive care unit. Neurologic examination continued to be normal. The chest drain was removed 4 days later and the patient was ambulated on the sixth postoperative day. Remaining kyphosis of 42° with no scoliosis was measured on standing radiographs (Fig.3). The patient was discharged on day 13 and he was able to return to his classes three months later. Cosmetic appearance was improved considerably (Fig.4). Final postoperative follow-up was at three years and included standing x-rays and careful neurologic examination. No neurological abnormality was detected and X-rays films showed solid fusion. 3. Discussion The hallmark of treatment of congenital kyphosis is anterior and posterior spinal fusion spanning the kyphotic segments. Particularly, kyphosis of less than 55° in growing children can be stabilized by posterior fixation only, but kyphosis greater than 55° require anterior and posterior stabilization 2'3. Active correction of kyphosis with instrumentation is dangerous and should be avoided. Most patients are treated with in situ anterior and posterior instrumentation placed following postural reduction Surgeon should assess the three-dimensional spinal anatomy on the coronal and sagittal plane and take into consideration the sagittal balancing of the spine5. Preoperative CT and MRI scan are indispensable. Same day surgery is preferable to staged surgery6 because the correction is better and the rehabilitation faster. We osteotomized the posterior column first and then reduced the deformity by anterior vertebrectomy and cage insertion. Finally, we compressed the posterior elements providing additional reduction and stabilization. All these steps were undertaken under direct cord vision and subsequent wake-up tests. The aim of surgical treatment of congenital kyphosis is to prevent deterioration of the deformity and onset of progressive neurologic sequelae. Active correction of the deformity should be limited and done with great caution. References 1. 2.

3. 4. 5.

6.

Winter RB, Moe h, Wang JF. Congenital kyphosis: It's natural history and treatment as observed in a study of 130 patients. J Bone Joint Surg [Br] 1975;57:138-141 Winter RB, Moe JH, Lonstein JE The surgical treatment of congenital kyphosis. A review of 94 patients age 5 years or older, with 2 years or more follow-up in 77 patients. Spine 1985;10(3):224-31 Mayfield JK, Winter RB, Bradford DS, Moe JH. Congenital kyphosis due to defects of anterior segmentation. J Bone Joint Surg Am 1980 ;62(8): 1291-301 Lenke GL. The pediatric spine. In: Dee R, Hurst L, Gruber MA, Kottmeier SA (ed.), Principles of orthopaedic practice.McGraw-Hill publishers, New York, 1998: p 1444-1445 DeWald RL. Osteotomy of the thoracic and lumbar spine. In: Bradford DS (ed.), Master techniques in orhopaedic surgery-Spine. Lippincott-Raven publishers, Philadelphia, 1995: p 229-248 Leatherman KJD, Dickson RA. Two-stage corrective surgery for congenital deformities of the spine. J Bone Joint Surg [Br] 1979;61(3):324-8

Th.B. Grivas (Ed.) Research into Spinal Deformities 4 1OS Press, 2002

The Role of Rigid vs. Dynamic Instrumentation for Stabilization of the Degenerative Lumbosacral Spine Panagiotis Korovessis, Zisis Papazisis, Elias Lambiris Orthopaedic Department, General Hospital "Agios Andreas" Patras, Greece Fax -.0030-610-361596, E-mail: [email protected]

Abstract Purpose of the study. This is a prospective comparative randomised study to compare the immediately postoperative effects of a rigid versus dynamic instrumentation for degenerative spine disease and stenosis on the standing sagittal lumbar spine alignment and to investigate if a dynamic spine system can replace the commonly used rigid systems in order to avoid the above mentioned disadvantages of rigid fixation . Material & Methods: 15 randomly selected patients received the rigid instrumentation SCS and an equal number of randomly selected patients the dynamic TWINFLEX device for spinal stenosis associated degenerative lumbar disease. The age of the patients, who received rigid and dynamic instrumentation was 65j-9 years and 62±10 years respectively. All patients had standing spine radiographs preoperatively and three months postoperatively. The parameters that were measured and compared pre- to postoperatively were: lumbar lordosis (LI-SI), total lumbar lordosis (T12-S1), sacral tilt, distal lordosis (L4-S1), intervertebral angulation, vertebral inclination and disc index. Results. The instrumented levels in the spines that received rigid and dynamic instrumentation were 3.5±0.53 and 3±Q.7 respectively. The instrumented levels from L3 to L5 were 23, the lumbosacral junction was instrumented in 3 patients of group A and in 4 patients of group B. Lumbar lordosis did not significantly change postoperatively, while total lordosis was significantly (P=0.04) increased in the patients who received the rigid instrumentation, while it was significantly (P=0.012) decreased in the group B. Intervertebral angulation of the non-instrumented level L1-L2 was increased in the group A (P=0.01), while the dynamic instrumentation increased (P=0.02) the intervertebral inclination of the adjacent level L2-L3, immediately above the uppermost instrumented level. Distal lordosis and sacral tilt did not change in any patient in both groups. Both instrumentations did not change the lateral vertebral inclination of LI to LS vertebrae. Rigid instrumentation increased the lordotic inclination of LS (P=0.03) and of SI (P=0.03). Rigid instrumentation increased (P=0.04) the intervertebral angulation at the uppermost instrumented level L3-L4 The most significant change in vertebral angulation was achieved at the instrumented level L4-LS by the dynamic (P=0.007) and rigid (O.OS). The disc index at the level L2-L3 was increased by both instrumentation [dynamic P=0.007 and rigid (P=0.02)]. The index L3-L4 was increased following dynamic fixation (P=0.0007). The disc index L4-L5 was postoperatively increased by both types of instrumentation (rigid P=0.006, dynamic P=0.02). The disc index L5-S1 did not significantly change postoperatively by either system. Conclusion: Both rigid and dynamic instrumentations restored lumbar lordosis, sacral tilt, distal lordosis and increased the foraminal diameter at the level L4-LS resulting in an indirect decompression of the nerve roots at this level . Both rigid and dynamic instrumentations applied in the lumbosacral spine to treat degenerative disease secured L3 to S, sagittal spine profile close to preoperative levels, that should theoretically guarantee a pain-free postoperative course. This study supports the belief that the dynamic system can be used with the same indications with the rigid in degenerative lumbar spine because it can offer equally good short-term results regarding sagittal spine alignment while

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simultaneously it has the previously mentioned advantages (avoidance stress shielding etc).

1. Introduction It is the belief of many spine surgeons[l,2] that rigid fixation usually causes stress shielding with subsequent bone mass reduction that may result in fracture of the osteoporotic spine (pedicle, laminae) with subsequent failure of fixation. Most of the spine surgeons believe that lumbar fusions with internal fixation should be performed in an intraoperative position, which recreates physiologic lordosis and maintains sagittal plane balance. The purpose of this prospective randomised comparative study was to show if the dynamic fixation has the same immediate postoperative effects on the sagittal alignment of the lumbar spine as the rigid fixation, performed on the same intraoperative position.

2. Material and Methods The patients who were included in this study were randomly selected and were divided in two groups (A and B) according to the instrumentation they received for symptomatic spinal stenosis associated degenerative lumbar spine disease. Fifteen patients (Group A) received the rigid SCS from titanium alloy (Eurosurgical, Beaurains, France) device (Fig 1). Twinflex (Eurosurgical, Beaurains, France) which is made from two pairs stainless steel rods of 2.5 mm diameter (Fig. 2). The Twinflex device is designed to obtain a better similarity between the elasticity of the grafted spine and instrumentation. No patient had had any prior spine surgery. The age of the patients, who received rigid and dynamic instrumentation was 65+9 years and 62+10 years respectively. All patients had standing radiographs of the lumbar spine preoperatively as well as three months postoperatively. The following roentgenographic parameters [7,8] were measured and compared in all spines: (1) lumbar lordosis (LI-SI); (2) total lumbar lordosis (T12-S1),(3) Sacral Tilt (4) Distal Lordosis (L4-S1), (5) Intervertebral Angulation (Fig.3); (6) Vertebral Inclination (Fig. 3); and (7) Disc Index (Fig. 3). The paired t-test and the one-way ANOVA were used for analysis of the data.. Each procedure included formal decompression and stabilisation with pedicle screws and posterolateral autogenous iliac bone grafting. All operations were performed by the senior author (P.K.) with the patient on a prone position on the Acromed frame (Acromed, Amsterdam, Holland) with four supports; two for shoulders and two for the pelvis to avoid pressure on the abdomen and the great abdominal vessels and thus to decrease intraoperative bleeding and the hips flexed at about 40°. In this position the gravity forces the lumbar vertebrae to a lordosis. 3. Results The results are shown in Table 1.

P. Korovexsis et al. / The Role of Rigid vs. Dynamic Instrumentation

4. Discussion The use of posterior instrumentation for the management of degenerative spinal deformities offers many potential advantages, including the restoration of a more accurate and physiologic alignment of the lumbar spine. Much of the literature suggests , and many surgeons anecdotally believe, that a loss of lumbar lordosis [1-5] after fusion surgery is associated with increased likelihood of breakdown of the adjacent unfused segment. If sagittal balance is to be maintained after posterior spinal fusion with instrumentation, the physiologic lordosis must be obtained by intraoperative positioning. Any intraoperative position producing a decrease of physiologic lordosis will result in a positive sagittal plane balance postoperatively [6]. Therefore, when instrumentation is used, appropriate positions reproducing physiologic lordosis must be used.. The preoperative and postoperative lumbar lordosis in the patients in both A and B groups were within the measured limits in the Greek population [7,8] and this did not changed postoperatively. The results of the present study regarding restoration of lumbar lordosis are supported by the results of the most recent clinical study [4], which suggested that lumbar fusion should be performed in normal lordosis or even slight hyperlordosis to protect the remaining segments from posterior overloading , or to prevent the onset of cartilage degeneration at neighbouring levels. Both instrumentations did not change the tilt of the sacrum.. In addition, distal lordosis (L4-S1), which represents the 70% of the lumbar lordosis [4,7,8] was not change by any instrumentation. The significance of increasing the disc index following instrumentation is that it is followed by increase of the diameter of the intervertebral foraminae, resulting in decompression of the emerging nerve root. A flexible stabilisation of the lumbar spine with the Graft ligaments [1] was reported previously without fusion with some advantages The dynamic instrumentation (Twinflex) that used in this series showed none of the reported disadvantages of the Graft ligament fixation. Because of the advantages of the dynamic versus rigid instrumentation (reduction of stress shielding , protection of adjacent segments, and avoidance of fracture of osteoporotic pedicles) the authors support the use of dynamic instrumentation in some selected prospective cases (e.g. osteoporotic spine). However, further long-term studies including radiological, subjective and clinical evaluation are necessary to justify the early radiological results derived from this preliminary comparative study in favour of dynamic fixation of lumbar spine in adult degenerated and osteoporotic spine. 5. Acknowledgement The authors wish to express their appreciation to Mr Georgios Korovesis School of Computer Science University of loannina for assistance in statistical analysis. References 1.

Gardner ADH An Alternative Concept in the Surgical Management of Lumbar Degenerative Disc Disease_Flexible Stabilization. Lumbosacral and Spinopelvic Fixation 1996.

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3.

4.

5. 6. 7.

8.

Goel VK.Lim TH.Gwon Jchen J.Y, Winterbottom JM, Park JB, Weinstein JN, Ahn JY. Effects of rigidity of an internal fixation device. A comprehensive biomechanical investigation. Spine 16(1991)155-161. Guanciale AF, Dinsay JM, Watkins RG. Lumbar lordosis in spinal fusion, a comparison of intraoperative results of patient positioning on two different table frame types. Spine 21 (1996) 964-969. Ijumi Y, Kumano K. Analysis of sagittal lumbar alignment and after posterior instrumentation. Risk factor for adjacent unfused segment. Eur J Ortho Trauma Surg Traumatology 11 (2001) 913. Kumar MN, Andrei Baklanov A, Chopin D. Correlation between sagittal plane changes and adjacent segment degeneration following lumbar spine fusion. Eur.Spine J 10(2001) 314-319. Stephens GC, Yoo JU, Wilbur G. Comparison of lumbar sagittal Alignment produced by different operative positions 21 (19%) 1802-07. Korovessis P, Stamatakis M, Baikousis A. Segmental roentgenographic analysis of vertebral inclination on sagittal plane in asymptomatic versus chronic low back pain patients. J Spinal Disord. 12(1999)131-137. Korovessis P, Stamatakis M, Baikusis A. Reciprocal anguiation of vertebral bodies in sagittal plane in an asymptomatic Greek population. Spine 23 (1998) 700-705.

Figure 1 : Segmental Contouring System (SCS) shown from above. Note the three phases of insertion (from top right to top left) of the clip to lock finally with top tightening system of fixation with a screw on the longitudinal rod.

Figure 2 : The twin stainless steel rods of the Twinflex - dynamic system shown from above. The rods of 2.5 mm are connected together and with the pedicle screw with an eyebolt

Figure 3 : Schematic demonstration of several roentgenographic parameters on the lateral lumbar spine. V.I.=vertebraI inclination, IVA= intervertebral anguiation, b/a = disc index.

Table 1 : Commutative Data of 30 Patients with degenerative spine disease who received Rigid or Dynamic Spinal Instrumentation

Parameters Age

Rigid preoperatively 65 +.9

Rigid postoperatively 65 + 9 49,6+13,6 49.6 _± 13.6 48 ±14.7 29±9 44±7 16±9 14±10 5.2 + 10 (-2)+_8 (-12) ±10

46+12 Total Lordosis Lumbar lordosis 46 ±13 Distal Lordosis 28±7 48 i 5.5 Sacral tilt 16+10 VI-L1 14+ 10 VI-L2 6.6~± 10 VI-L3 0.7 + 15 VI-L4 VI-L5 (-8) + 15 IVA L1-L2 6±-3 6±3 10±3 IVA L2-L3 10±4 IVA L3-L4 7.8 ±.5 8.5 ± 5 IVA L4-L5 9.6 + 5 10±5 Dl L1-L2 0.47 ±0.1 3 0.48 ± 0.1 Dl L2-L3 0.41 ± 0.05 0.42 ±0.08 Dl L3-L4 0.38 ±0.1 0.40 ±0.1 Dl L4-L5 0.4 ± 0.1 0.46 ± 0.1 0.36 ±0.1 Dl L5-S1 0.4 ± 0.1 All data are shown as mean ± Standard deviation, Dl=disc index

Significance level (P) NS

Dynamic preoperatively 62±10

Dynamic postoperatively 62±10

Significance level (P)

0.04 0.06 NS NS NS NS NS NS NS 0.01 NS 0.04

48±11 46.5 ±1 1 32 ±8 45 + 3.5 16_±11

46.6 ± 10.8 45.6 ±11 31±8 45 ± 3.7 16±11 14±11 7.7 ±7.5 (-0.5) ±6.6 (-11.0)± 7 5± 3 8.5 * 4

0.012 NS NS NS NS NS NS NS NS NS 0.02 NS

14±11 7±7

NS

(-1.2) ±6 (-10.7) ±8.7 3.3 ± 5 7.5± 4 8±4 7.6 ±3.5 0.007 10± 5 0.005 11.51 5 0.4 ± 0.1 0.47 i 14 NS NS 0.007 0.02 0.38 ± 0.07 0.47 ±0.08 0.0007 0.37 ± 0.7 0.48 1 0.08 NS 0.02 0.37 ± 0.07 0.006 0.4 ± 0.06 NS 0.36 ± 0.06 0.34 ± 0.05 NS P-values paired t-test, VNvertebral inclination, IVA=intervertebral inclination

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Spine Deformity Correlates Better Than Trunk Deformity with Idiopathic Scoliosis Patients' Quality of Life Questionnaire Responses Marc Asher, Sue Min Lai, Doug Burton, Barbara Manna Kansas University Medical Center, Kansas City, Kansas USA Abstract. Aim : To determine whether either spine or trunk deformity measurements correlate with patients quality of life questionnaire responses. Materials and Methods: Forty five pre operative patients (5M, 40F), average age 15 years, 9 months (range, 10-20) met the inclusion criteria of age (£ 20 years), Posterior Trunk Symmetry Index (POTSI) and Suzuki Hump Sum (SHS) determination from surface topography, and Scoliosis Research Society -22 (SRS-22)patient questionnaire completion. Average measurement and measurement ranges were largest Cobb 62° (range, 40-137 °), POTSI 49 (range, 17-149), SHS 16 (5-32), and SRS-22 subtotal score 3.86 (range, 4.7-2.35). The individual SRS-22 domain scores were function 4.13 (4.80-2.20), pain 4.01 (51.60), self image 3.34 (4.4-1.80) and mental health 4.01 (5-1.80). (Scale 5 Best1 Worst). Correlations between deformity and questionnaire measurements were determined, p<0.01 considered significant. Results: Spine deformity (Cobb) correlated with the SRS-22 subtotal scores (cc04207, p<0.005) and with the function and self image SRS-22 domain scores: ccO.5182, p<0.001) and cc-0.3981, p<0.01 respectively. Neither trunk deformity score correlated with the SRS-22 Score: POTSI versus SRS-22 (cc 0.0449, ns) and SHS versus SRS-22 (cc-0.0311, ns) Conclusion: Spine deformity correlates well with quality of life questionnaire responses whereas trunk deformity magnitude does not. This is somewhat surprising as it is the trunk deformity that the patient can they themselves see. These findings illustrate the pitfalls of assuming what is important to the patient based on clinical measurements.

1. Aim

The relative importance of spine and trunk deformity to the patient with idiopathic scoliosis is unknown. The hypothesis of this study is that trunk deformity is more important to this patient than spine deformity. 2. Materials and Methods Patients operated from January 1, 1999 through July 31, 2001 were considered for inclusion. The inclusion criteria were diagnosis of idiopathic scoliosis; an age of twenty years or younger; pre-primary surgery whether posterior, combined, or anterior; one surgeon (MA); one hospital (KUMC); and one instrumentation (Isola).

M. Asher el a/. /Spine Deformitv Correlates Better than Trunk Deformity

These patients preoperatively had both surface topography (rasterostereography, Quantec) and the SRS-22 health-related quality of life questionnaire1'2'3 completed. The largest Cobb angle and curve pattern were determined by viewing coronal plane radiographs. The thoracic curves included King Moe HI, IV, and V curves. Double curves included King Moe I and II curves. It also included the triple curves. The thoracolumbar curves had an apex at T12, the T12-L1 disc, or LI. Some had a compensatory thoracic curve while others did not. The Posterior Symmetry Index (POTSI) 4>5 was the topographic variable for the coronal plane and in the transverse plane the Suzuki Hump Sum (SHS).6 The study group was described by descriptive statistics. The Fisher Exact Test was used to determine the difference between groups and the Pearson Correlation Coefficient to determine the relationship of radiographic and topographic variables with the SRS-22 health-related quality of life questionnaire. Findings were considered to be statistically significant at p< 0.01 and marginal at p<0.1.

3. Study Group Of the 59 patients operated in the study time interval, 50 (85%) met the inclusion criteria. Seven were males and 43 were females. Their average age was 15 years, 8 months (range, 10 years, 1 month-20 years, 10 months). The mean Cobb angle of these 50 patients was 63° (range, 40°-137°), POTSI 50 (range, 17-149), and SHS 15 (range, 4-33). POTSI component average asymmetry values were for medial lateral offset C7=6.2 (range, 0-18), axilla 15.8 (range, 12-165), and trunk 14.9 (range, 15-43). For vertical offset asymmetries they were shoulder 2.0 (range, 0-6), axilla 5.5 (3-12), and trunk 8.3 (0-25). The Hump Index 1 (HIX1) component of the Suzuki Hump Sum was 2.8 (range, 2-12), HIX3 6.5 (range, 6-16), and HIX 5 6.0 (range, 5-9). The SRS-22 scores for the 50 patients were function 4.1 (range, 2.2-4.8), pain 4.0 (range, 1.6-5), self-image 3.3 (range, 1.8-4.4), mental health 4.0 (range, 1.8-5), and subtotal 3.9 (range, 2.4-4.7). 4. Results Spine deformity (Cobb) correlated significantly with function (r -0.49, p 0.0003) and self-image (r -0.40, p 0.004). There were no correlations between POTSI or SHS and SRS-22. No single component of the POTSI correlated significantly or marginally with SRS-22. The HIX1 component of the Suzuki Hump Sum correlated significantly with function (r -0.47, p 0.0007) and self-image (r -0.39, p 0.005).

5. Discussion These results were surprising and unanticipated. Our explanation for them is that the posterior exposure surface topography is a poor measure of what patients actually see as they view themselves from the front.

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6. Conclusion The hypothesis was disproved. We learned instead that spine deformity is apparently more important to the patient than coronal or transverse plane trunk deformity. 7. Acknowledgments The authors wish to thank Terry Orrick, academic secretary, and Barbara Funk, editor, for their assistance in the preparation of this manuscript. This study was supported in part by the Scoliosis Research Fund, Kansas University Surgical Association.

CONFLICT OF INTEREST DISCLOSURE: correction stability... This volume.

See Asher et al: Trunk deformity

References 1. 2.

3.

4.

5.

6.

Asher M, Lai SM, Burton D, Manna B. The reliability and concurrent validity of the SRS-22 patient questionnaire for idiopathic scoliosis. Spine (accepted). Asher M, Lai SM, Burton D, Manna B. Discrimination validity of the Scoliosis Research Society-22 Patient Questionnaire: Relationship to Idiopathic Scoliosis (IS) Curve Pattern and Curve Size. Spine (accepted). Asher M, Lai SM, Burton D, Manna B. Scoliosis Research Society-22 patient questionnaire responsiveness to change associated with surgical treatment: Preliminary results. Spine (resubmitted). Inami K, Suzuki N, Ono T, Yamashita Y, Kohno K, Morisue H: Analysis of Posterior Trunk Symmetry Index (POTSI) in scoliosis. Part 2. ID Research into Spinal Deformities, edited by I.A.F. Stokes, IOS Press, Amsterdam, The Netherlands, 1999. Suzuki N, Inami K, Ono T, Kohno K, Asher MA. Analysis of Posterior Trunk Symmetry Index (POTSI) in scoliosis. Part 1. IQ Research into Spinal Deformities 2, edited by I.A.F. Stokes, IOS Press, Amsterdam, The Netherlands, 1999. Suzuki N, Ono T, Tezuka M, Kamiishi S. Moire Topography and Back Shape Analysis Clinical Analysis: International Symposium on 3-D Scoliotic Deformity. Edited by J Dansereau, Gustav Fisher Verlag, Montreal 1992; 124-130.

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The Rib Hump after Surgery for Early Onset Spinal Deformity CJ.Goldberg. D.P.Moore. E.E.Fogarty. F.E.Dowling. Children's Research Centre & Orthopaedic Department, Our Lady's Hospital for Sick Children, Crumlin. Dublin 12. Ireland e-mail: caroline.goldberg(a).ucd.ie/fax +353-1-455-0201 Abstract Spinal deformity presenting early in childhood has a poor prognosis, in that progression is probable and severe respiratory compromise is a real possibility. Treatment is difficult, since these patients frequently do not respond to bracing, and surgery is sometimes performed in childhood in an attempt to control relentless progression. This carries the risk of continued deformation during subsequent growth, and the surgical procedures have been adapted in an attempt to minimise this. 25 children undergoing spinal fusion for progressive and severe deformity have sequential topographic scans which show that, despite measures to control the rib hump, progression after surgery is the rule.

1. Introduction James in 1954 [5] wrote that he had "so far hesitated" to operate on the spine of a patient less than 10 years old, although he did not discuss his reasons. Subsequent experience with posterior spinal fusion, as described by Dohin and Dubousset [3], showed further deformity was the rule with this manoeuvre and proposed that this could be prevented by the addition of an anterior spinal fusion. This, it was argued, would prevent the growth of the anterior part of the spine which drove the rotational deformity (so-called crank-shaft phenomenon), resulting in a short but straight spine and a controlled minimal rib-hump. This study examined the topographic records of children whose spinal surgery was before the age of 10 years, asking if this prediction has been born out by experience. 2. Materials ad Methods Subjects for this study were patients with non-congenital spinal deformity, either idiopathic or syndromic, who underwent corrective spinal surgery before age 10 years and who have serial post-operative topographic scans to assess the status of the rib hump. The topography system used is Quantec Image Processing [2] and is routinely used for all deformity patients on all clinic visits as well as before and after surgery at this centre. The technique, as described elsewhere [4], entails the taking of four repositioned scans of the patient and subsequently averaging each result in order to minimise the error margins. For the purposes of this study, all criteria (Table) routinely measured were considered. For those patients who have pre-operative scans, change resulting from surgery was analysed. To these were added those whose surgery took place before the introduction of the surface topography system but who

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C.J. Goldhen; ct
have serial topographic images taken since then. These were analysed for change over time. 3. Results There were 25 patients, 15 male and 10 female, who had corrective spinal surgery before the age of 10 years. Diagnoses were infantile idiopathic scoliosis (IIS) N=12, juvenile idiopathic scoliosis (JIS) N=2 and syndromic scoliosis (2°S) N=l 1. Of these, 10 have pre- as well as postoperative surface topography. Deformity was in the sagittal plane for two: a girl with severe post-laminectomy at the thoraco-lumbar junction who underwent osteotomies and anterior and posterior fusion at age 8.2, is now 13.9, post-menarche and well balanced; a boy with ligamentous laxity and severe kyphosis who had 3-stage surgery, osteotomy, anterior and posterior spinal fusion at age 8.2. He suffered a fractured rod at age 10.7, necessitating replacement and refusion, and has suffered significant recurrence of his kyphosis. The remaining 8, 4 boys and 4 girls, with a diagnosis of IIS (N=3), JIS (N=l) and 2°S (N=4) 7 had anterior growth arrest and posterior instrumentation at a mean age of 6.8 years + 2.04, range 3.2 - 9.3. One had anterior growth arrest only. Although surgery produced an immediate improvement visible to the eye, the figures do not achieve statistical significance, perhaps due to the small sample size. Apparent improvements, i.e. of more than 10 units [4] were observed in spinal angles (15.5 for the upper and 18.85 for the middle angle) and the posterior trunk symmetry index (16.8 improvement). A further 12 children have serial topography post-operatively, although their surgery was before the introduction of the system and they have no pre-operative data. Their age at surgery was 4.8 years + 2.3, range 1.4 - 8.4. Topography was first performed at a mean age of 12.6 years ± 3.47, range 8.46 to 18.6, which was a mean of 7.8 years + 4, range 1.2 - 13.4 years after surgery. Many of these patients had their surgery over 15 years ago, and they show a variety of procedures: 3 had posterior instrumentation, either Luque trolley of subcutaneous Harrington rod, with anterior growth arrest only several years later, when its importance became known. 10 had anterior growth arrest as a primary procedure combined with either Luque segmental wiring, Harrington fusion or Cotrel Dubousset instrumentation. One had a Zielke anterior fusion followed by Cotrel Dubousset instrumentation. One patient, a male with cleido-cranial dysostosis and a primarily kyphotic deformity underwent subcutaneous Harrington rod at age 3.5, six subsequent adjustments of the rod and anterior growth arrest. His current cosmesis at age 19.7 is of significant deformity, but that has been stable over 5 years from age 14. There were 22 children, 9 girls and 13 boys, whose surgery for idiopathic or syndromic scoliosis took place before the age of 10 years and who have serial postoperative topographic scans. The first post-operative scan was at a mean age of 10.7 + 3.9 years, range 4.2 - 18.6, which was at a mean of 5.15+ 4.77 years after the first surgical procedure, range 0.053 - 13.4 years. The last post-operative scans were at a mean age of 14.3 + 4.4 years, range 5.2 - 22.9, after a mean interval of 6.6 + 1.6 years. The parameters considered (Table) showed a tendency to increase, except for the sagittal angles. However, this only reached statistical significance in the case of the Suzuki hump sum, which increased by a mean of 7.4 units + 14.9, p=0.03. Age at first surgery correlated with statistical significance with the most recent hump asymmetries (r=-0.527, p=0.03).

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4. Discussion This is a difficult class of patients to study, whether they are taken in precise diagnostic categories or in larger and more mixed groups. A major problem is the sheer length of time required before they reaches maturity in sufficient numbers, their sporadic and varied presentation and the ever-changing philosophy of treatment. The older patients in this group were treated by techniques that would not be considered now, and instrumentation and approach are significantly more sophisticated. Furthermore, those patients with pre-operative topographic records are still prepubertal, and so it cannot yet be stated that the more modern techniques will adequately control the rib hump, or whether costoplasty will be an effective remedy for failure. It is however opportune to consider that the prognosis for early onset scoliosis is for relentless progression in most cases, and that the purpose of early surgery is to prevent not only this continued deformation but also the consequent respiratory deficit, morbidity and early mortality described by Branthwaite [1]. The impression in the clinical field, particularly now that surface topography has led to much closer scrutiny of cosmetic result and visible deformity, that while early surgery balances the trunk and keeps the head square over the pelvis, the rib hump recurs and negates the cosmetic improvement caused by the surgical procedure.

5. Conclusion Because of small numbers and long time-frame, meaningful conclusions on treatment efficacy will be slow and tentative, yet this is the category of scoliosis that cause most difficulty in the clinical situation and is discussed the least. It is not even clear whether these patients can be saved from the pulmonary sequelae of their condition. Outcome studies are needed, so that at least ineffective treatments may be abandoned and realistic goals identified. References 1. 2. 3.

4. 5.

Branthwaite MA. (1986) Cardiorespiratory consequences of unfused idiopathic scoliosis. Br.J.Dis.Chest 80:360-369. Curran P. Groves D. (1990) Assessing spinal deformities. Image Processing, Capture, Management and Analysis. 2:14-16. Dohin B. Dubousset J.F. (1994) Prevention of the crankshaft phenomenon with anterior spinal epiphysiodesis in surgical treatment of severe scoliosis of die younger patient. European Spine Journal. 3(3):165-8. Goldberg CJ. Kaliszer M. Moore DP. Fogarty EE. Dowling FE. (2001) Surface topography, Cobb angles and cosmetic change in scoliosis. Spine. 26:E55-63. James JIP. (19S4) Idiopathic scoliosis: the prognosis, diagnosis and operative indications related to curve patterns and the age of onset J.Bone & Joint Surg. 36-B(l ):36-49.

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C.J. Goldberg el al. / The Rih Hump after Surgery for Eurl\ Onset Spinal Deformin

Table Surface topography parameters considered 1. Trunk balance T,S,O Displacement of first thoracic vertebra over sacrum. POTSI Posterior trunk symmetry index 2. Lateral spinal curve Ql A Upper spinal angle Q2A Middle spinal angle Q3A Lower spinal angle 3. Sagittal profile TK LL

Thoracic kyphosis Lumbar lordosis

4. Back asymmetry AS 1A AS2A AS3A SHS

Inclination at upper maximum asymmetry point (rib hump) Inclination at middle asymmetry point Inclination at lower asymmetry point Suzuki hump sum

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Trunk Deformity Correction Stability Following Posterior Instrumentation and Arthrodesis for Idiopathic Scoliosis Marc Asher, Sue Min Lai, Doug Burton, Barbara Manna Kansas University Medical Center, Kansas City, Kansas USA Abstract. Aim: To determine whether trunk deformity correction is stable over time. Materials and methods: Thirty - seven patients (5M, 32 F) average age 16 years, 3 months (range, 10 to 38) met inclusion crieteria of primary posterios instrumentation (ISOLA) and arthrodesis with x-ray and surface topography measurements [Posterior Trunk Symmetry Index (POTSI)] and [Suzuki Hump Sum (SHS)] pre-operatively and at 2 years follow up. For 30 patients measurements were also available post - operatively. Patient's average pre, post, and two- year measurements were: Largst Cobb 65 ° (±12), 21 ° (±8), and 21 ° (±17) ; POTSI 53 (±29), 28 (±12); and 22° (±10); and SHS 18 (±11), 12 (±7), and 12 (±7), and 12 (±6). Statistical analysis was done with the sign test, comparing only patients with data at the intervals studied. Surface topography measurements were considered to be unchanged/tied unless they increased or decreased by more than 8 for POTSI and 3.5 for SHS, Significance was set at p<0.05. Results: POTSI changes were pre-to post operative: 20 improved (I), 3 worsened (W), and 7 tied (T) (p<0.01): pre to two years: 30 (I), 4 (W), and 3 (T) (p<0.01): and from post to two years: 14 (I), 3 (W) and 13 (T) (p<0.01). SHS changes were pre to post to two years: 18 (I), 2 (W), and 11 (T) (p<0.01); pre to two years: 23 (I), 2 (W), and 11 (T) (p<0.01); ad post to two years: 4(1), 6 (W), and 20 T (ns). Conclusion : Trunk deformity improvement following surgery is stable or improved over time with surgical techniques utilized.

1. Aim

Limited transverse plane deformity correction has been reported following corrective surgery for adolescent idiopathic scoliosis.8 Furthermore, any transverse plane trunk deformity correction achieved has been reported to recur during follow up.7 Since 1985 we have pursued possible surgical solutions including torsional, countertorsional instrumentation; stable, strong and durable constructs; and ample arthrodesis.1'2 We have had promising results experimentally being able to block the crankshaft mechanism,6 and blocking the crankshaft phenomenon clinically in girls age 10 years and older4. We have also had promising trunk results utilizing the transverse plane major angle of trunk inclination.3 The hypothesis for this study is that transverse plane and coronal plane trunk asymmetry correction is achieved and maintained with the surgical technique utilized.

M. Asl\er el ul. / Trunk Defnrmitv Correction Stability

2. Materials and Methods Patients who had surgery between April 1, 1996, when we began using surface topography techniques, and December 31, 1999 were candidates for inclusion in this study. The inclusion criteria were primary posterior surgery with no supplemental anterior surgery, one surgeon (MA), one hospital (KUMC), one instrumentation (Isola), and pre- and 2-year follow-up surface topography. Spine deformity was measured by the Cobb method on 36" (91 cm) radiographs taken at a 72" (183-cm) tube film distance. The threshold for change was set at ±5°. Posterior coronal plane trunk symmetry was measured using the Posterior Trunk Symmetry Index (POTSI)5'9 Transverse plane trunk asymmetry was measured using the Suzuki Hump Sum (SHS).8 The threshold for change was set at ±8 and ±3.5, respectively.10 The study group was characterized by descriptive statistics. Change over time was determined with the Signed Rank test. Percent improvement between groups was determined by the Fisher Exact Test. Differences of p< 0.01 were considered significant and p<0.1 marginal. 3. Study Group Of the 60 candidates, 38 patients (63%) met inclusion criteria. The latest surface topography studies were done at a mean of 25 months postoperative (range, 20-48 months). Thirty-one patients also had early postoperative surface topography at a median of 1.5 months (range, 2 weeks-6 months) postoperative. Nineteen of the 22 patients not meeting inclusion criteria had either been operated early in the series when we were getting accustomed to surface topography or they were followed in a field clinic more than 100 miles (220 kilometers) from the medical center. One had moved to another state, one was lost to follow-up, and one had sustained a hip fracture at the time follow-up was due. The study group included 34 females and 4 males whose average age was 16.1 years (range, 10 years, 7 months-38 years, 2 months). Twenty-nine had thoracic curves, and 9 had double curves. There were marginally more thoracic curves in the study group than the 22 patients not eligible for study (p=0.02). There were no significant differences between the study group and non-study group in terms of preoperative and postoperative Cobb measurements. There were no serious complications such as death, paralysis, early or delayed deep wound infection, or pseudoarthrosis in either group. There have been no reoperations in either group to date. The mean pre-, early, and latest measurements for the 38 patients in this study were as follows: Cobb 64°, 20°, 23°; POTSI 54, 26, 20; and SHS 19, 13, 11. 4. Results All Cobb measurements were improved early and late, pO.OOOl. POTSI changes were pre- to early 25 improved, 4 same, and 2 worse (p<0.0001); pre- to

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latest 33 improved, 4 same, and 1 worse (pO.OOOl); and early to latest 13 improved, 16 same, and 2 worse (p<0.008). Suzuki Hump Sum scores were pre- to postoperative: pre- to early 20 improved, 9 same, and 2 worse (p<0.0001); pre- to latest 28 improved, 8 same, and 2 worse (p<0.0001); and early to latest 6 improved, 22 same, and 3 worse (ns).

5. Conclusion In this study population using the techniques described, transverse plane asymmetry was significantly decreased following surgery and remained stable at 20 to 48 months postoperative. In the coronal plane mere was also significant asymmetry decrease following surgery. In addition, there was further significant improvement at the 20 to 48 month follow-up. These findings support the surgical principles utilized in the treatment of these patients. 6. Acknowledgments The authors wish to thank Terry Orrick, academic secretary, and Barbara Funk, editor, for their assistance in the preparation of this manuscript. This study was supported in part by the Scoliosis Research Fund, Kansas University Surgical Association. CONFLICT OF INTEREST DISCLOSURE: Dr. Asher owns 30% of Isola Implant Inc., which has an exclusive license agreement with DePuy AcroMed. He is not a DePuy AcroMed officer, director or shareholder. Dr. Asher is reimbursed for some expenses related to DePuy AcroMed-sponsored medical meetings. In the past, Dr. Asher has provided paid consulting services to DePuy AcroMed, but he is not presently providing such services. Dr. Asher has voluntarily donated to public charity approximately 60 percent of his income from Isola Implants, Inc. and from consulting work he has performed for DePuy AcroMed. References 1. 2. 3. 4. 5.

6.

Asher M.A.: Isola spinal instrumentation system for scoliosis. In The Textbook of Spinal Surgery. Edited by Bridwell, K.H., and Dewald, R.L. Philadelphia, Lippincott, pp. 569-609, 1997. Asher MA and Burton DC. A concept of idiopathic scoliosis deformities as imperfect torsion(s). Clin. Orthop. 1999; 364:11-25. Burton DC, Asher MA, and Lai SM: The selection of fusion levels using torsional correction techniques in the surgical treatment of idiopathic scoliosis. Spine 1999; 24:1728-1739. Burton DC, Asher MA, and Lai SM. Scoliosis correction maintenance in skeletally immature patients with idiopathic scoliosis: Is anterior fusion really necessary? Spine 2000; 25:61-68. Inami K, Suzuki N, Ono Y, Yamashita Y, Kohno K, Morisue H. Analysis of posterior trunk symmetry (POTSI) in scoliosis. Part 2. In IAF Stokes (ed), Research into spinal deformities 2, IOS Press, Amsterdam, Netherlands, 1999. Kioschos HC, Asher MA, Lark RG, and Hamer EJ. Overpowering the crankshaft phenomenon: The effect of posterior spinal fusion with and without stiff internal fixation on anterior spinal column growth in immature canines. Spine 1996; 21:1168-1173.

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7.

8. 9. 10.

Pratt RK, Webb JK, Burwell G, and Cole AA. Changes in surface and radiographic deformity after universal spine system for right thoracic adolescent idiopathic scoliosis: Is rib hump reassertion a mechanical problem of the thoracic cage rather than an effect of relative anterior spinal overgrowth? Spine 2001; 16:1778-1787. Suzuki N, Ono T, Tezuka M, Kamiishi S. Moire topography and back shape analysis-clinical application, in J Dansereau (ed). International Symposium on 3-D Scoliotic Deformities, Gustav Fisher Verlag, Stuttgart, 1992; pp. 124-128. Suzuki, N, Inami K, Ono T, Kohno K, and Asher MA. Analysis of posterior trunk symmetry index (POTSI) in Scoliosis. Part 1. ]Q Research into Spinal Deformities 2. Edited by Stokes, I.A.F. Amsterdam, IOS Press, pp 81-84, 1999. Suzuki N, personal communication, 1998.

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Anterior Universal Spine System (US S) for Adolescent Idiopathic Scoliosis (AIS): a Follow-up Study using Scoliometer, Real-time Ultrasound and Radiographs R. G. Burwell', K. K. Aujla', A. A. Cole', A. S. Kirby', K. K. Pratt1, J. K. Webb' and A. Moulton2 'The Centre for Spinal Studies and Surgery#, Queen 'S Medical Centre, Nottingham & 2 Department of Orthopaedic Surgery, King's Mill Hospital, Mansfield, England. Abstract. Nine patients with AIS treated surgically with anterior USS instrumentation were examined by several methods pre-operatively and at each of 8 weeks, 1 year and 2 years after surgery (mean age 14.6 years, girls 7, boys 2, thoracolumbar 7, lumbar 1, thoracic 1, left 7, right 2). The methods used were (1) Scoliometer to measure angle of trunk inclinations (ATIs) in the standing forward bending position at each of 10 levels and converted to 18 levels by a computer program, (2) realtime ultrasound in the prone position of laminal rotations at each of 1 8 levels from TI-SI, and (3) anteroposterior radiographs in the standing erect position measured for each of Cobb angle, segmental vertebral rotation (Perdriolle) and segmental vertebral translation from the Ti-Si line (horizontal translation of each vertebral centroid from the T1-S1 line). The findings were plotted graphically and segmentally for each of Scoliometer ATJs, ultrasound laminal rotations, and radiographic vertebral rotations and translations. Findings. Graphical representation of the data shows that the improvement brought about by surgery is most clearly and consistently evident for segmental vertebral translation. The statistical analysis shows that the radiological parameters (Cobb angle, apical vertebral rotation and apical vertebral translation) and ultrasound spinal (laminal) rotation do not change detectably in followup. The Scoliometer ATI findings show an increase from 4 degrees (at 8 weeks) to 7 degrees (at 2 years) which is statistically significant. The evidence from this small sample of patients is consistent with the view that the compared with posterior USS, anterior USS surgery for AIS results in (1) similar initial rib hump correction, and (2) less rib hump reassertion during follow-up. More data are needed to evaluate these views. -Supported by AO/ASIF Research Commission Project 96-W21

1. Introduction Pratt et al F51 reported findings for the effects of the posterior Universal Spine System (USS) on the surface and radiological deformity of 27 patients with right thoracic adolescent idiopathic scoliosis (AIS). The patients were evaluated preoperatively and longitudinally at each of 8 weeks, one year and 2 years afier surgery both radiologically and for surface back shape using a Scoliometer to measure

R.C

angle of trunk inclinations (ATIs) at 10 levels on the back. Almost half the initial back surface correction is lost by 2 years. Rib-hump reassertion was explained by unwinding of the thoracic cage tensioned by surgery rather than through relative anterior spinal overgrowth. In this paper preliminary findings are reported of the effects of anterior USS on patients with adolescent idiopathic scoliosis (AIS) on each of back surface asymmetry, ultrasound spinal rotation and radiological features. 2. Material and Methods 2.1 The patients, spinal curves and examinations After informed consent from the parents/guardians nine patients having anterior USS were included in the study (7 girls and 2 boys, mean age 14.6 years). The spinal curves were thoracic 1, thoracolumbar 7, lumbar 1 with a mean Cobb angle of 45 degrees, left 7, right 2). Each patient was examined and measured preoperatively, and at each of 8 weeks, 1 year and 2 years after surgery. 2.2 Scoliometer surface angle of trunk inclinations (ATJs) Surface back shape was examined in the standing forward bending position [2,51 using the Scoliometer down the back from Ti-Si by one observer (RKP). The skin on the subject's back was marked at ten equally spaced points between the vertebra prominens and the mid-sacral point (half way between the dimple of Venus). Scoliometer angle of trunk inclinations (ATI) at each level were obtained. The maximal ATI was used in the evaluation of the findings [51. 2.3 Ultrasound spinal (lam inal) rotations In the prone position the patient lies on a hard couch with her forehead supported on a stand, the arms dependent and the anterior superior iliac spines in contact with the couch [1 ,3,41 The transducer is aligned with the laminae or ribs to produce a horizontal image on the display monitor and readings made directly from the Scoliometer attached to the probe. The child was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). The ultrasound equipment included an Aloka SSD 500 portable machine with a 3.5 MHZ wide field of view (172 mm) linear array transducer. A commercial Scoliometer was positioned on the transducer and used to read the angles of inclination relative to the horizontal to the nearest 0.5 degrees for the laminae and ribs at each level. The maximal spinal (laminal) rotation was used in the evaluation of the findings. 2.4 Radiological measurements Anteroposterior radiographs in the standing erect position obtained preoperatively and at each of 8 weeks, 1 year and 2 years after surgery were measured by one observer (KGB) for each of Cobb angle, segmental axial vertebral rotation (Perdriolle), and segmental vertebral translation of the centroid of each vertebra from the Ti-Si line [5],

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2.5 Right humps, rotations and vertebral translations are assigned positive values and left hump rotations and vertehral translations negative values In plotting the ATI, ultrasound and segmental radiological data for right humps, rotations and translations were assigned positive values and left humps, rotations and translations negative values. The maximal ATI, maximal vertebral rotations and maximal translations were established from visual examination of the plots. 2.6 Mean A TJ and spinal ('am inal) rotation corrected for side In calculating the mean maximal values of ATI, ultrasound spinal (lamina!) rotation and Perdriolle rotation the figures were made positive (corrected for side). 2.7 Statistical analyses The effects of surgery and changes in follow-up were evaluated using a paired ttest. 3. Results Graphical representation of the data shows the improvement brought about by surgery is most clearly and consistently evident for segmental vertebral translation. The findings for the mean figures after correction for side are shown in the Table for each of Cobb angle, apical vertebral rotation (AYR), apical vertebral translation (AVT), maximal Scoliometer ATI (Scol ATI), and maximal ultrasound laminal rotation (U/S LR). Table. Radiological, ultrasound and Scoliometer findings for patients having anterior USS (Means, n=9) Parameter Cobb angle

AYR AVT Scol ATI U/SLR

Preop

45° 29° 37mm

15° 18°

8 weeks PI

*** *** 14mm *** ** 4° * 9°

22° 19°

1 Year

21° 18°

P2 2 Years

NS NS 12mm NS 6° NS 7° NS

23° 15° llmm

7° 7°

P3/4/5 NS/***/NS NS/***/NS NS/***/NS NS/***/* NS/***/NS

The Table shows P values for paired t-tests on comparisons preop/8 weeks (PI), 8 weeks/i year (P2), 1 year/2years (P3), preop/2years (P4) and 8 weeks/2years (PS, * 0.01
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R G. Burwi-ll a al. / Anterior Universal Spine S\:
and 2 years -from the 16 patients in the study. Only one of the spinal curves is thoracic compared with all the curves in the posterior USS study [51. 4.2 Radiological and ultrasound parameters in follow-up All parameters are improved by anterior surgery at 8 weeks. In subsequent follow-up to 2 years most parameters do not change detectably. This includes Cobb angle, apical vertebral rotation, apical vertebral translation and ultrasound spinal (laminal) rotation. 4.3 ScoliometerA TI findings in follow-up The Scoliometer ATI findings show an increase in follow-up from 4 degrees at 8 weeks to 7 degrees at 2 years which is statistically significant (P--0.046). 4.4 Scoliometer A TI findings after posterior USS After posterior USS for thoracic AIS [5] the mean maximal ATIs were preoperatiyely 16.8 degrees, at 8 weeks 9.7 degrees, at 1 year 12.9 degrees and at 2 years 13.1 degrees; the rib hump reassertion during follow-up is statistically significant. 4.5 Comparison offindings after anterior and posterior USS The evidence from this small sample of patients is consistent with the view that the compared with posterior USS, anterior USS surgery for AIS results in (1) similar initial rib hump correction, and (2) less rib hump reassertion during follow-up. More data are needed to evaluate these views. References 1.

2.

3.

4.

5.

R.G. Burwell et ai, Evaluation of vertebral rotation by ultrasound for the early detection of adolescent idiopathic scoliosis. In, Research into Spinal Deformities 2. I.A.F. Stokes (ed.), pp 7376, Amsterdam:IOS Press, 1999. R.G.Burwell et al, Back shape assessment in each of three positions in preoperative patients with adolescent idiopathic scoliosis (AIS): evaluation of a 10-level Scoliometer method interpolated to 18-levels. In, Research into Spinal Deformities 4. T B Grivas (ed.), pp xx, Amsterdam:IOS Press, 2002. R.G.Burwell et al., Preliminary study of a new real-time ultrasound method for measuring spinal and rib rotation in preoperative patients with adolescent idiopathic scoliosis. In, Research into Spinal Deformities 4. T B Grivas (ed.). pp xx. AmsterdanrlOS Press, 2002. A.S. Kirby et al, Evaluation of a new real-time ultrasound method for measuring segmental rotation of vertebrae and ribs in scolisois. In, Research into Spinal Deformities 2. I.A.P. Stokes (ed.), pp 316-320, Amsterdam:!OS Press, 1999. R.K. Pratt et al. Changes in surface and radiographic deformity after Universal Spine System for right thoracic adolescent idiopathic scoliosis. Spine 26(16): 1778-1787,2001.

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Long-term Follow-up of Surgically Treated AIS Patients D. Hill(1), V.J. Raso(I), K. Moreau(l), M. Moreau(2), J. Mahood(2) 'Capital Health Authority, Glenrose Rehabilitation Hospital Site, Edmonton, AB Canada 2 Department of Surgery, University of Alberta, Edmonton, AB Canada dhill@cha. ab. ca Abstract. The aim of this study was to determine the long-term changes in spine and trunk alignment in patients who have undergone scoliosis surgery. Twenty-three (16F; 7M; at age of surgery 15.7+4.9 years) patients with adolescent idiopathic scoliosis agreed to participate and had posterior-anterior radiographs and surface topography prior to derotation surgery, within 6 months of surgery, at 2 years post-operatively and 5-10 years (mean follow-up period 6.11+ 1.6 years) after surgery. Cobb angles, surface trunk rotations, and cosmetic scores were measured at each visit. A questionnaire assessed back appearance and pain at the 5-10 year follow-up. The results of the questionnaire were compared to 25 patients with idiopathic scoliosis who had recently undergone surgery. A paired two-tailed Student's t-test with p=0.05 was used to compare the deformity between visits. The Cobb angle and cosmetic score improved after surgery while the change in trunk rotation was insignificant (p=0.37). Between the two-year and 5-10 year review, the Cobb angle, cosmetic score, and surface trunk rotation significantly increased. Selfperception of appearance and pain were similar to the control group. Surgical correction of scoliosis is not completely maintained during adulthood although the radiographic and surface deterioration does not appear to be clinically significant.

1. Introduction Patients who have surgery to treat their scoliosis are routinely followed until 18 years of age in pediatric scoliosis clinics. After this, they may be seen through the physician's offices at the request of the patient. This protocol is typical in many scoliosis programs, therefore little is known about the stability of the spine or trunk during adulthood [1]. Many of the patients in the scoliosis program ask how their condition will affect them during adulthood. The generally accepted belief is that the spine is rigidly fixed by the instrumentation and progression of the deformity is stopped. It is possible, though, for the spine to twist above and below the instrumentation causing further deformity. This twisting is due to the continued growth of the patient's body, both above and below the fusion, after surgery. Most studies represent the radiographic results of scoliosis surgery and less importance is placed on the external trunk deformity. Posterior-anterior (PA) and lateral radiography is the most common method used to determine spinal alignment. The spatial alignment of the spine is difficult to reliably establish radiographically after surgery for two reasons. Spinal instrumentation is radio

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D. Hill et ai /Long-term h'ollow-iip of Surgically Treated AIS Patients

opaque and blocks visualization of the spine. Also many of die anatomical landmarks used to estimate vertebral alignment in space are obliterated during surgery. Surface topography was used to supplement the information from the radiographs. Trunk rotation (twisting) and the cosmetic score were obtained from images of the external trunk. Surface topographies and radiographs were performed prior to surgery and postoperatively at regular intervals until the patients reach 18 years of age. The goal of this study was to determine the long-term changes in spine and trunk alignment after surgery for scoliosis.

2. Materials and Methods Fifty patients were identified as candidates for this study, twenty were lost to follow-up and seven declined to take part. Of the remaining twenty-three candidates (77% participation), 16 were females and 7 were males with a mean age at surgery of 15.7 + 4.9 years. These patients all had derotation surgery between 1990 and 1996 to treat adolescent idiopathic scoliosis. Surface topography measurements and radiographs were performed pre-operatively and during the follow-up period of at least two years. As part of the study, all study patients returned 5-10 years (mean follow-up period 6.9 + 1.5 years) after their original surgery for repeat surface topography and radiographs. At this time, patients completed a questionnaire that assessed back pain, opposite sex relations, back appearance, and effect of treatment [3,4]. Internal spinal deformity was assessed by measuring die Cobb angle on a posterior-anterior radiograph. A paired 2-tailed student's t-test was used to determine if the internal spinal deformity had changed by a statistically significant amount (p<0.05). Surface topography assessed the cosmetic features associated with scoliosis. Trunk rotations and the cosmetic score [2] were used to describe the cosmetic deformity. A paired 2-tailed Student's t-test was performed to determine whether the surface topography had changed by a statistically significant amount (p<0.05). A questionnaire regarding back appearance, opposite sex relations, back pain, and treatment was completed at this visit. Each question was marked on a scale from 1-6, where 1 was the most negative answer, and 6 was the most positive answer. Questions were placed in the four previously mentioned categories and the scale was remapped from 0 to 100 (0=worst; 100=optimum). These results were compared with a control group of 25 patients (24 female, 1 male; mean age 15.1 + 1.7 years) who had completed the questionnaire within two years of surgery. Both control and experimental groups underwent surgery at the same institution by the same surgeons.

3. Results The mean pre-operative Cbbb angle was 59° ± 11° and the mean immediate postoperative Cobb angle was 34° ±11°. The Cobb angle continued to increase postoperatively (Figure 1). Trunk rotation decreased from 14° ± 9° pre-operatively to 12° ± 7° post-operatively. The change was minimal after surgery, however it also increased in the follow-up period (Figure 2). Cosmetic score (Figure 3) decreased after surgery from 3.7 ± 2.5 to 2.0 ± 0.7, however it also followed the same pattern as the previous two examples. Figure 4 displays the categories of self-perception of pain, opposite sex relations, back pain, and treatment effects are similar to that of the control group.

D. Hill et al. /Long-term Follow-up of Surgically Treated AIS Patients

Figure 2. Trunk Rotation Pre/Post Surgery

Figure 1. Cobb Angle Pre/Post Surgery

Cosmetic Score

3 5 Years Post-op

Figure 3. Cosmetic Score Pre/Post Surgery

Figure 4. Questionnaire

Cobb angle and cosmetic score decreased significantly after surgery while changes in trunk rotation were insignificant. All three parameters increased significantly at each follow-up point (Table 1). Both internal and external spinal deformity measurement worsened between the two-year post-operative visit and the 5-10 year visit. Table 1: Statistical significance of the deformity related to scoliosis prior to surgery and following surgery at 6 months, 2 years and 5-10 years. PO.05 shown as * and p<0.01 shown as **. Parameter Cobb Angle Trunk Rotation Cosmetic Score

Pre- vs 6 mon

Pre- V8 2 vrs Pre- vs 5-10 vrs 2 vrs vs 5-10 vrs

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/) Hill cl til /Long-term Follow-up of Surgically Treated AIS Patients

4. Conclusion The cosmetic score and Cobb angle improved significantly following surgery. The trunk rotation, however, was not statistically different following surgery. All three scores showed deterioration 5-10 years after surgery. This implies that the trunk continues to deteriorate after the spine has presumably fused. The back appearance, opposite sex relations, back pain, and effect of treatment at 5-10 years following surgery were not statistically different from the control group. Although the changes in the three measurements were statistically significant, the lack of change noted from the questionnaire suggests that the changes after surgery may not be important to the patients.

References 1. 2. 3. 4.

Smucker JD, Miller F: Crankshaft Effect after Posterior Spinal Fusion and Unit Rod Instrumentation in Children with Cerebral Palsy. JPO 21 (2001) 108-112. Raso VJ, Lou E, Hill DL, Mahood JK, Moreau MJ, Durdle NG: Trunk Distortion in Adolescent Idiopathic Scoliosis. JPO 18 (1998) 222-226. Marsh, HW: Self-Description Questionnaire - II. University of Western Sydney, Macarthur, August 1990 Raso VJ, Hill DL, Magill-Evans J, Bering M, Mahood MK, Moreau MJ: Perception of Body Image in Children with Scoliosis. In: J.A. Sevastic, K.M. Diab, (eds.), Research into Spinal Deformities 1, ISBN: 90 5199 308 0. IOS Press, Oxford, 1997. pp. 397-399.

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Assessing the Impact of Pelvic Obliquity in Post-operative Neuromuscular Scoliosis M. Moreau(1), J. Mahood(1), K. Moreau(2), D. Berg(2), D. Hill (2) , J. Raso(2) 'University of Alberta, Edmonton, AB Canada Capital Health Authority, Glenrose Rehabilitation Hospital Site, Edmonton, AB Canada mmoreau@ualberta. ca

2

Abstract. The goal of this pilot study was to explore the relationship between pelvic obliquity and patient pain, sitting tolerance, pressure sores, and function. Five neuromuscular patients who underwent spinal surgery 6-26 weeks prior to assessment took part in this on-going study (4F; 1M); age at surgery (14.6 ± 2.6 years). Pelvic obliquity was measured from pre- and postoperative anterior-posterior radiographs. A force-sensing pad with a grid of sensors was placed on a flat surface and the weight distribution pattern was recorded. The pressures were divided into left and right sides and peak levels were noted on each side. The parents or caregivers completed a questionnaire on their child's pain, sitting tolerance, pressure sores, and functional abilities. Pelvic obliquity was reduced after surgery by approximately 50% depending on the method used to assess pelvic obliquity. The major curve was reduced from 64°(10°) to 39° (10 ). Post operatively, the average pressure (left/right side) ranged from 1.2 to 2.0 (average 1.6). The peak pressure ratio ranged from 1.1 to 1.9 (average 1.4). The ratio of left/right pressure correlated with improvement in pelvic obliquity (^=0.9). Pain was moderate/severe in the 2 patients with the least correction as measured with the Cobb angle from surgery; both improved following surgery. Two patients suffered pressure sores pre-operatively and one post-operatively. Only 3/5 felt sitting endurance had increased. All parents felt their child sat straighter after surgery. The outcome measures of pain, pressure sores, sitting tolerance, and function were not well related to the amount of pelvic obliquity. More candidates and a longer follow-up may shed light on die many relationships.

1. Introduction Pelvic obliquity generally refers to a pelvis that does not lie horizontal in the frontal plane and is usually associated with scoliosis in many neuromuscular conditions. The aim of scoliosis surgery is to correct or stabilize the deformity to achieve the best sagittal as Well as postural balance, equally distribute weight over the ischial tuberosities, and place the head over the trunk. Pelvic obliquity is generally only partially corrected in this process. The effect of partial correction is not well understood with most research in this area focused on assessing different surgical approaches in institutionalized patients with extreme deformity. The incidence of pelvic obliquity in the neuromuscular population has been shown to be quite variable [1-3]. Many approaches have been used to measure pelvic obliquity [2,4-11]; suggesting a lack of consensus on what pelvic obliquity truly is.

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M. Moreun ct til. /A\xi: the Impact nf Pelvic Ohliquit\

2. Objective The objective of this pilot study was to explore the relationship of residual (postoperative) pelvic obliquity to patient pain, sitting tolerance, pressure sores and function. 3. Methods and Materials 3.1 Subjects The inclusion criteria for this study were adolescent, non-ambulatory, cerebral palsy patients that previously had undergone surgery for the correction of scoliosis and pelvic obliquity with a post-operative follow-up visit of 6-26 weeks. Five consecutive patients (4 female, 1 male) with an average age of 14.6 + 2.6 years (range 11.2 - 17.4) met these criteria. All five underwent posterior instrumentation and fusion including screw fixation of the instrumentation to the sacrum. Institutionalized patients were excluded from this study. 3.2 Radiography Each patient obtained sitting, anterior-posterior scoliosis radiographs preoperatively as well as at the post-operative follow-up visits as part of the standard clinic assessment. Cobb angles and measurements of pelvic obliquity were obtained for each radiograph by two clinicians. Pelvic obliquity was measured using three commonly used methods. The first method [4,7] consisted of drawing a line across the superior margins of the iliac crests; the angle between this line and the horizontal was called the "Pelvic Obliquity Iliac Crest." The second method [7] involved drawing a line across the superior end plate of SI. The angle between this line and the horizontal was called the "Pelvic Obliquity SI." The third method [2,5,8-11] consisted of drawing a line across the superior margins of the iliac crests, and another line from the center of Tl to the center of S1. The angle between a perpendicular to T1-S1 and the iliac crest was called the "Pelvic Obliquity Trunk." 3.3 Questionnaire During the follow-up visit, a research assistant administered a questionnaire to the patient (or to the parent/caregiver on the patient's behalf)- Questions were related to their spinal deformity and were asked for the time period one year prior to their surgery and for their current follow-up visit. Questions included sections on the necessity for repeat hospital admission and treatment, pain, wheelchair use, modifications required for their chair, weight distribution in their chair, pressure sores, and changes in functional ability. 3.4 Weight Distribution A seating assessment was performed to determine weight balance by using the TEKSCAN [12] system. The TEKSCAN consisted of a force-sensing conductive inkpad with a grid of sensors; it was placed on an examination bed to measure the patient's weight distribution. The weight distribution pattern was recorded after two minutes of sitting and measurements were taken three times for a duration of twenty seconds at lOHz. These three repeated measures were averaged. The patterns were divided into left and right sides and peak levels were noted on each side. Repeatability testing with a 45kg test object and a normal subject showed that the TEKSCAN measures took more than a minute to stabilize.

M. Moreau et ai /Assessing the Impact of Pelvic Oblic/nitv

4. Results Due to the small sample size and the non-homogeneity of the patient population further group analysis was difficult and statistically insignificant. The outcome measures of pain, sitting tolerance, pressure sores, and function were not well related to the amount of pelvic obliquity. The ratio of left/right pressure correlated with improvement in pelvic obliquity (r2=0.9). The results shown in Table 1 are of note. Table 1. Radiographic and Pressure Measurements

Measure (PO = Pelvic Obliquity) Pre-Op PO Iliac Crest Post-Op PO Iliac Crest Change in PO Iliac Crest Pre-Op PO SI Post-Op PO SI Change in PO SI Pre-Op PO Trunk Post-Op PO Trunk Change in PO Trunk Pre-Op Cobb Post-Op Cobb Change in Cobb Percent Change in Cobb TEKSCAN: Mean Post-op sitting asymmetry Left / Right TEKSCAN: Peak Post-op sitting asymmetry Left / Right

Mean (SD) 10.3(6.1) 6.0(5.4) 4.3(2.2) 22.2(13.4) 14.2(12.2) 8.0(6.0) 15.8(8.8) 8.8(9.0) 7.0(4.6) 64(9) 43(14) 21(10) 33%(16) 1.6(0.4)

3-17 0-11 2-7 2-37 0-30 2-16 5-23 1-20 3-11 55-78 25-63 15-38 19-60 1.2-2.0

1.5(0.3)

1.1-1.9

Range

Two patients had less pain post-operatively than pre-operatively, while another two had no pain either pre- or post-operatively. Three of the five patients had never suffered pressure sores while one had pressure sores in the year before surgery and one post-operatively. All five patients felt that they sat straighter in their wheelchairs after surgery. Three felt that sitting balance had improved after surgery, while one thought it had worsened. Three felt that eating/feeding was easier after surgery. Two felt that they could sit in their wheelchair for longer periods of time post-operatively, while one felt that his/her ability to sit in place had decreased. All patients sat with more weight on their left side.

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M. Moreau er a/. / Axscsshm the Impact of Pelvic ()bli
5. Discussion Due to the non-homogeneous nature of this limited patient group, it is not yet possible to make any conclusive statements relating the degree of pelvic obliquity and its correction to changes in pain, seating requirements/ability, pressure sores, or function. The situation is complicated by the diverse measurements and corrections achieved for pelvic obliquity. Of the three measurements taken to assess pelvic obliquity radiologically, those done on the iliac crests were generally the smallest in magnitude, followed by "the trunk measurement", and then by "SI". The measurement error on picking out landmarks especially on the post-operative radiographs was relatively high compared to the size of the deformity measured (signal/noise ratio is low). Missing landmarks caused by coning of the radiographs to reduce radiation exposure added further difficulty to measuring. The percentage change was relatively consistent between techniques. Each measurement technique demonstrated further shortcomings: the iliac crest and the trunk measurements both relied on the pelvis being square to the x-ray film; however, rotation of the pelvis in the transverse plane shortens the lever arm, increasing the perceived angle. The SI measure is susceptible to a similar problem, as it is often difficult to find SI landmarks, particularly after instrumentation. The iliac crest measure and SI measure have strength as they are relative to the horizontal, whereas the trunk measure is not. The necessity for surgical correction is disputed for severely involved institutionalized patients. Our group included only those patients of sufficient neurological maturity who would benefit from the surgical procedure in a lifelong way with every chance of a good outcome. It is often difficult to completely correct the pelvic obliquity associated with neuromuscular scoliosis. Analyzing the effects of this residual deformity from a clinical point of view is important. Clinical outcomes need to be tied to measured clinical and radiological parameters. Despite the difficulties in accurately measuring pelvic obliquity on radiographs, the combination of pressure measurements, radiological findings and the responses of caregivers to a well-structured questionnaire offer the beginnings of some answers to the nature and degree of problems associated with residual pelvic obliquity.

6. Conclusion At present it is too early to come to a conclusive agreement in regards to how residual post-operative pelvic obliquity affects pain, sitting tolerance, pressure sores, and function, neither from the literature nor from the limited results of this study. There may be some indication that patients with residual pelvic obliquity after spinal surgery accommodate to the imbalance and the clinical outcome may be satisfactory; rigorous measures to correct pelvic obliquity may not be necessary.

References 1. 2. 3. 4.

D. Hart et al.. Spinal Deformity in Progressive Neuromuscular Disease. Rehabilitation of Neuromuscular Disease, 9(1) February 1998, 213-232. W. Bulman et al.. Posterior Spinal Fusion for Scoliosis in Patients with Cerebral Palsy: A Comparison of Luque Rod and Unit Rod Instrumentation. JPO, 16(3) (19%) 314-323 J. Lonstein et al.. Treatment of Spinal Deformities in Patients with Cerebral Palsy or Mental Retardation. JBJS, 65-A(l) (1983) 43-55. M. Yazici et al.. The Safety and Efficacy of Isola-Galveston Instrumentation and Arthrodesis in the Treatment of Neuromuscular Spinal Deformities. JBJS. 82-A(4) (2000) 524-543.

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5.

6. 7. 8. 9. 10.

11. 12.

485

C. Whitaker et al., Treatment of Selected Neuromuscular Patients with Posterior Instrumentation Ending with Lumbar Pedicle Screw Anchorage. Spine, 25(18) (2000) 23122318. S. Sprigle et al., Using Seat Contour Measurements During Seating Evaluations of Individuals with SCI. Assistive Technology, 5(1) (1993) 24-35. M. Sussman et al., Posterior Instrumentation and Fusion of the Thoracolumbar Spine for Treatment of Neuromuscular Scoliosis. JPO, 16(3) (1996) 304-313. C. Comstock et al., Scoliosis in Total-Body-Involvement Cerebral Palsy. Spine, 23(12) (1998) 1412-1425 R. Dias et al., Surgical Correction of spinal Deformity Using a Unit Rod in Children With Cerebral Palsy. JPO, 16(6) (1996) 734-740. W. Maloney et al., Simultaneous Correction of Pelvic Obliquity, Frontal Plane, and Sagittal Plane Deformities in Neuromuscular Scoliosis Using a Unit Rod with Segmental Sublaminar Wires: A Preliminary Report. JPO, 10(6) (1990) 742-749. L. Rinsky, Surgery of Spinal Deformity in Cerebral Palsy. Clinical Orthopaedics and Related Research, #253, April 1990, 100-109. M. Ferguson-Pell et al., Prototype Development and Comparative Evaluation of Wheelchair Pressure Mapping System. Assistive Technology, 5 (1993) 78-9.

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Is This As Good As It Gets? It May Be. Marc Asher Kansas University Medical Center, Kansas City, Kansas USA

The history of the development of spinal arthrodesis, beginning with the 1941 study of Shands et al reporting a pseudoarthrosis rate of 28% and 69% fair or poor results using the techniques of the time, was reviewed.9 By 1960, two major advances had occurred. First was the systematic and determined approach of John Moe, M.D., to perfect the techniques and performance of arthrodesis and casting.8 Second was the development of the first effective spinal instrumentation by Paul Harrington, M.D., whose work was stimulated by the polio epidemics in the years immediately following World War II. 710 Adopting these advances, Nachemson developed a series of 156 consecutive patients of whom 142 (91%) could be located for study at a minimum of 20 years' follow-up.3'4 Their curve (Cobb) average was 61.8° preoperative and 36.5° at latest follow-up, a 41% lasting correction. There were no deaths, paralysis, or either acute or delayed deep wound infections. The pseudarthrosis rate was 3 of 142 (2%) and the reoperation for instrument-related problems 8 of 142 (5.6%). Based on a health-related quality of life questionnaire (SF-36), the mental component summary score for the patients was not significantly different from controls, 50.9 patients versus 50.1 controls. The physical component summary (PCS) score was significantly lower for the patient group than the control, p<0.0001. However, the numerical differences were small, 49.2 for patients versus 53.1 for controls. The authors also reported a companion group of 116 brace-treated patients who also had a minimum 20-year follow-up. Their average curve (Cobb) was 33.2° pretreatment and 37.6° (-13%) at latest follow-up. There were no significant differences in the SF-36 scores between the brace and surgery groups. Is this as good as it gets? It may well be. To my knowledge, there are only two studies with follow-up approaching this length. Dickson et al reported on Harrington's patients at an average of 21 years' follow-up.5 Of 111 patients with radiographs taken at least 18 years postoperatively, 32 (29%) had had reoperation. Connolly et al, who were able to trace only 83 of 142 patients (58%) from 10 to 16 years postoperative, reported 18 of 81 (22%) had had reoperation.2 Based on responses to a patient questionnaire, 66% had achieved excellent or good results compared to 93% for controls. As reviewed in my keynote lecture, knowledge of the natural history of adolescent idiopathic scoliosis provides reassurance that the trade-offs between a curved and mobile spine versus a straighter but stiff spine do not seem favorable for the latter until approximately a 55-60° residual curve (Cobb) at maturity.1 Exact treatment guidelines are impossible to establish because of the many variables, including the patient's own perception of their condition.

M. Asher / Is This As Good Ax It Gets? It May Be.

In this regard it is useful to consider the statement of the late Robert Gillespie.6 "The medical community's perception of the significance of idiopathic scoliosis has altered with the developing history of medicine. In the preradiologic era the occasional very severe forms of the disease were assumed to be related to poliomyelitis or tuberculosis, at that time the well recognized causes of spinal deformity. The moderate or milder forms were known to be common in young girls, ignored in the lower social orders, and considered unfortunate hindrances to marriage among young ladies of the middle and upper classes of society. The latter group were treated according to the fashion of the time by everything from brine baths and elaborate exercises to complex spinal orthotics, differing in some cases very little from modern bracing except for the sophistication of the material." A small minority of adolescent idiopathic scoliosis patients may experience more problems, most of which will respond to behavioral modifications. Such changes include smokers ceasing to smoke; achieving proper nutrition, for those with BMI greater than 25 losing weight and those under 19 gaining weight; participating in aerobic conditioning, with various methods available but one of the best being pool walking, and trunk strength and flexibility maintenance through instruction in and occasional monitoring of a self-performed exercise program. Occasional use of pain medication may be needed, but continuance or escalation must be avoided. A few adult scoliosis patients will present with pain severe enough to consider surgery. Usually there is axial pain, but occasionally it may be extremity pain, more commonly due to subarticular or foraminal stenosis than central stenosis. The most important aspect of these patients' work-up is to rule out co-morbidities, including spondylolisthesis or spondylolysis; primary degenerative spondylosis; metabolic bone disease, such as idiopathic osteoporosis or hyperparathyroidism; and systemic arthropathy. Even though the deformity size and vital capacity support the prognosis that the patient is not at risk of premature death, surgical treatment may occasionally be justified. Self-image/appearance is another common reason for patients to present for consideration of surgery. It is very important for the patient and the surgeon to have realistic expectations as to what can be accomplished, realizing that trunk realignment becomes increasingly difficult with each decade of life. Very occasionally, shortness of breath will be the presenting symptom. If the patient has pulmonary function decrease to the point of threatening longevity, the diagnosis of adolescent idiopathic scoliosis should be questioned and other etiologies for the scoliosis and symptomatology sought. Occasionally an adult with adolescent idiopathic scoliosis may have enough shortness of breath to warrant surgical treatment even though the pulmonary function studies are not decreased enough to suggest a threatened life expectancy. Finally, it is inevitable that some patients previously operated will become symptomatic at some point. The most common pathology is secondary degeneration at the junction of the previous fusion. Due to continued evolution of the spine deformity surgery, including anterior discectomy and arthrodesis, posterior osteotomy, more complex posterior osteotomy reaching the anterior portion of the spine through one of several pedicle center oriented techniques, and improved instrumentation, salvage surgery is becoming more reliable. In conclusion, until there is a substantial breakthrough in our knowledge of the pathogenesis of idiopathic scoliosis, the generally accepted options for management available today seem adequate, and the answer to the rhetorical question "Is this as good as it gets?" seems to be "Yes." To avoid backsliding, careful

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application of available knowledge and techniques allows most patients with late onset juvenile or adolescent idiopathic scoliosis to function at normal or near normal levels throughout life. Acknowledgments The authors wish to thank Terry Orrick, academic secretary, and Barbara Funk, editor, for their assistance in the preparation of this manuscript. This study was supported in part by the Scoliosis Research Fund, Kansas University Surgical Association. CONFLICT OF INTEREST DISCLOSURE: See Asher et al: Trunk deformity correction stability... This volume.

References 1. 2.

3.

4.

5. 6. 7. 8. 9.

10.

Asher M. Long term effects of scoliosis. Keynote address, IRSSD 2002, Athens, Greece. Connolly, P.J.; Von Schroeder, H.P.; Johnson, G.E.; and Kostuik, J.P.: Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine. J Bone Joint Surg77-A: 1210-1216, 1995. Danielsson, A.; Wiklund, I.; Pehrsson, K..; Nachemson, A.: Health-related quality of life in patients with adolescent idiopathic scoliosis-A matched follow up at least 20 years after treatment with brace or surgery. Euro Spine J 10:278-288, 2001. Danielsson AJ, Nachemson AL. Radiologic findings and curve progression 22 years after treatment for adolescent idiopathic scoliosis: Comparison of brace and surgical treatment with matching control group of straight individuals. Spine 26:516-525, 2001. Dickson, J.H.; Erwin, W.D.; Rossi, D.: Harrington instrumentation and arthrodesis for idiopathic scoliosis: A twenty-one year follow up. J Bone Joint Surg 72-A:678-683, 1990. Gillespie, R.: Juvenile and Adolescent Idiopathic Scoiiosis. IQ The Pediatric Spine. Bradford, D.S. and Hensinger, R.M. eds. Thieme, Inc., New York, 1985. pp. 233-250. Harrington, P.R.: Treatment of scoliosis. Correction and internal fixation by spine instrumentation. J Bone Joint Surg 44-A:591-611, 1962. Moe, J.H. and Gustillo, R.B.: Treatment of scoliosis: Results in 1% patients treated by cast correction and fusion. J Bone Joint Surg 46A: 58-77, 1964. Shands, A.R., Jr.; Barr, J.S.; Colonna, P.C.; Noall, L.: End-result study of the treatment of idiopathic scoliosis: Report of the Research Committee of the American Orthopaedic Association. J Bone Joint Surg 22:963-977,1941. Tambornino, J.M.; Armbrust, E.N.; and Moe, J.H.: Harrington instrumentation in correction of scoliosis: A comparison with cast correction. J Bone Joint Surg 46A:78-88, 1964.

Th.B. Grivus (Ed.) Research into Spinal Deformities 4 1OS Prexx. 2002

Modification of the spinal peak growth velocity as a possible treatment for adult scoliosis Professor Andrew G. King, MD, Department of Orthopaedics, Pediatric Orthopaedics, Pediatric Spine Surgery, Children's Hospital, Louisiana State University Health Science Center, New Orleans, Louisiana USA. 1-800-299-9511, Office 504/896-9569, Fax 504/896-9849, e-mail: [email protected]

It is well known that there is a spurt of growth in early adolescence, a few years prior to full maturity. This has been termed the adolescent growth spurt (AGS). It is now known that this growth spurt occurs mainly in the spine. Characteristics of the adolescent growth spurt have been clearly described by J.M. Tanner in his landmark work "Growth at Adolescence" (1962). The increased rate of growth reaches a peak before falling off to zero when the person reaches maturity. This peak is called the peak growth velocity (PGV). The characteristics of growth during the adolescent growth spurt are fairly regular from one individual to another. However, there is considerable variability in the age of onset between individuals and between males and females. Studies looking at events occurring during the adolescent growth spurt (such as hormone levels) show widely varying results when based on chronologic age, since any one chronologic age could encompass those who had an early growth spurt and in whom growth has terminated, and those patients just entering into a late growth spurt. For this reason, Tanner suggested making comparisons by identifying the timing of the peak growth velocity and measuring growth by the months or years before and after mis peak. By plotting growth, not against chronologic age, but against "a measure which arranges the children according to how far they have progressed along their course of development" gives much more meaningful information. Boys and girls have very similar growth up until the time of the adolescent growth spurt. Girls enter the adolescent growth spurt at an average age of 11.6 years. Boys enter the growth spurt more than two years later, at an average age of 14. The difference in adult height is mainly based on this extra two years of growth for boys. The adolescent growth spurt itself is very similar between the sexes, with boys having an average peak growth of 7 to 12 cm and girls 6 to 11 cm. Children who have their peak early reach a higher peak than those who have it late. For many years, scoliosis has been thought to be a disorder of growth. It is most commonly seen during times of rapid growth, either at adolescence or in the infantile age group. Studies have shown that girls who develop scoliosis are taller than their peers prior to the onset of the adolescent growth spurt. The vertebral bodies of children with scoliosis have been shown to be taller than those without. Also, it had been proposed that children who develop scoliosis have different characteristics to their growth spurt than those who do not. For example, the onset may be at a greater rate and the peak height velocity at a higher level than those who do not develop scoliosis.

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However, the work of Duval-Beaupere showed the characteristics of the AGS and the amplitude of the peak are no different in those children with scoliosis compared with those who did not. While the AGS remains the most important factor in scoliosis progression, it is not in and of itself a cause of scoliosis. Identifying the timing of the AGS and in particular the peak growth velocity is important in treatment decisions for patients with scoliosis. Little showed that patients with curves 30 degrees or more prior to the peak growth velocity had an 83 percent chance of progressing to 45 degrees or more, whereas those who had a curve of less than 30 degrees at the time of peak growth velocity, only 4 percent progressed to 45 degrees or more. The timing of the peak growth velocity is a much more sensitive indicator of growth remaining than onset of menarche, Risser sign, chronologic age/ or even bone age. The hormonal control of the AGS has been debated for sometime. Early studies suggested growth hormone and androgens. Scoliosis has been reported to develop in patients treated with growth hormone, but the treatment is usually for a condition in which growth has been retarded and in whom there is a growth spurt after the onset of the treatment. This is not analogous to adolescent idiopathic scoliosis. It has now been clearly shown that estrogen in both boys and girls in relatively low doses is the principle mediator of the adolescent growth spurt. In males, most of the estrogen is derived from the effect of the hormone aromatase on testosterone and androstanedione. However, estrogen has a biphasic effect. While it stimulates the adolescent growth spurt, it is at the same time initiating the final maturation of the epiphysis, leading to the end of growth. A possible cause for the difference in scoliosis rates between girls and boys is that girls begin their adolescent growth spurt at the onset of puberty, whereas boys are in advanced puberty before entering the adolescent growth spurt. Therefore, the adolescent growth spurt in boys is superimposed on a more mature and presumably more stable spine. The medication Lupron is used for the treatment of precocious puberty. It works by blocking the release of follicle stimulating hormone, which in turn blocks the release of estrogen. Children who are identified as being at risk of developing severe scoliosis and are about to enter their adolescent growth spurt could have the onset of the AGS delayed by this medication. Delaying the onset of the AGS by one to two years would mean the AGS would then be superimposed on a more mature and presumably more stable spine. In addition, there is evidence that the peak height velocity would be less than it would have been at the earlier age. Theoretically, there would be little loss of height caused by this therapy since the children would have an extra year or two of growth. They would be at no greater risk of osteopenia than those who naturally have a delayed onset of the adolescent growth spurt. This treatment could be used in conjunction with a brace or independent of a brace. Other therapeutic interventions could possibly involve selective estrogen receptor, blocking gents, and for boys aromatase inhibitors. In summary, more is known about the adolescent growth spurt including its characteristics in males and females and its hormonal control. There is no dispute that the adolescent growth spurt may be a cause for rapid progression of a preexisting scoliosis, although it does not appear to be a primary cause of the scoliosis understanding of the hormonal regulation has led to medications such as Lupron, which can be used to delay the onset of the adolescent growth spurt This has possible

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applications in the treatment of children identified with scoliosis who have not yet reached their peak growth velocity. References 1. 2.

3.

4.

Tanner, J.M. 1962, Growth at Adolescence. 2nd Edition. Oxford: Biackwell. Little, D.G./ Song, K.M./ Catz, D./ Herring, J.A. "Relationship Peak Height Velocity to Other Maturity Indicators in Idiopathic Scoliosis in Girls". Journal of Bone and Joint Surgery, Vol. 82A ft5/ May 2000, page 685. Duval-Beaupere, G. "Pathogenic Relationship Between Scoliosis and Growth in Scoliosis and Growth". Proceedings of a Third Symposium Held at the Institute of Disease of the Chest, Brompton Hospital, London, November 1970. Ed. P.A. Zorab/ M.D./ M.R.C.P. Grumbach, Melvin M. Journal of Pediatric Endocrinology and Metabolism #13. Pages 14391455,2000.

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Th.B.GrivastEd.i Research into Spinal Deformities 4 IOS Press 2
Outcomes of Scoliosis Fusion Is Stiff and Straight Better? Morey S. Moreland, M.D. Children 'S Hospital of Pittsburgh, aizd Department of Orthopedic Surgery, University of Pittsburgh School ofMedicii- e, 3705 Fifth Avenue, Pittsburgh, PA J52J3, USA Management of spinal deformity in individuals with significant deformity due to adolescent idiopathic scoliosis has evolved over the last 40 years. Through the work of Dr. Paul Harrington [1], instrumentation of the spine at the time that an arthrodesis is performed has become the standard for both improving the degree of correction of the deformity as well as improving the rate of fusion and preventing the formation of a pseudarthrosis. The method of fixation of the instrumentation to the spine at the time of the arthrodesis has also evolved from a 1" generation use of a single rod Harrington rod that was attached at the proximal and at the caudal end of the fusion. Initial surgical attempts using this technique failed to appreciate the importance of the sagittal plane and often the rods were inserted as a straight rod, failing to allow for the normal kyphosis and lordosis of the spine. Later modification of the Harrington rod instrumentation and the and development of 2nd generation instrumentation allowed for contouring of the rods to accommodate the normal sagittal plane curvature. This segmental fixation nature allowed for more fixation points and thus created the potential for obtaining greater correction of the coronal plane deformity. It has been shown that even with newer instrumentation, transverse plane corrections are small compared to that attainable in the sagittal plane, and certainly less than that attainable in the coronal plane [2,3]. Initial corrections of the primary deformity with the Harrington rod approached 50%, but with multiple fixation points, correction of the coronal plane deformity can be as much as 70-75% in young flexible patients. The purpose of this discussion is to raise some questions regarding the possible negative effects on the un-fused portion of the spine following spinal instrumentation and fusion, and to see if there are indications of possible symptomatic or functional problems arising from the long-term effects of spine fusion. Are our efforts to obtain maximal correction of the frontal plane deformity leading to secondary problem in the future? 1. The Problem Currently, the four most common reasons given for performing an arthrodesis of the spine for scoliosis are: 1) The deformity will increase over time, 2) There will be pulmonary or cardiac de-compensation, 3) Degenerative arthritis of the spine will occur, 4) The back "looks bad"; there is a cosmetic concern. If we are to be effective in our treatment we should at least address these concerns. Aside from the known acute and chronic complications associated with the performance of the surgical procedure, which will not be addressed here, our concerns should address both

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inability of accomplishing the goals of surgery, and the potential secondary problems that could or would occur in the long term as a result of the procedure. In keeping with our stated goals of surgical intervention is there evidence that the deformity is increasing or is degenerative arthritis occurring in spite of fusion? And lastly, is the back straighter and does it maintain this appearance over time either from the patient's or the surgeons perspective? A successful arthrodesis of the spine straightens the spine and creates a stiff segment over the fused region of the spine. If successful, further progression over the fused segments should not occur. In most long term series there is only a small loss of the original correction postoperatively [6,15,18,19]. Since motion within the fused segment is eliminated, arthritis in that segmental portion of the spine should not occur. The correction should be greatest in the coronal plane, least in the transverse or axial plane, and moderate in the sagittal plane. These are the primary effects of a successful fusion What are the secondary effects? Because of the long lever arm flexibility is concentrated to the junctional areas at the cranial and caudal ends of the fusion mass, and increases the demands on the remaining segments to accommodate to the reduced flexibility. Kapandji [25] has shown that in the coronal plane the total lateral bending of 75 degrees is made up of equal flexibility of the thoracic and lumbar bends each accounting for approximately 20 degrees. The sagittal plane range of motion is more dramatic totaling 250 degrees, 40 degrees of which are made up of thoracic motion, and 115 degrees in the lumbar; 35 degrees in extension and 75 degrees of flexion. There for, if there are five motion segments within the lumbar spine and a spine fusion extends to L3, and each segment contributed equally to lumbar motion, there would be three-fifths or 60 percent reduction in motion for the lumbar region. In addition, it has been shown that the sequence in the normal flexion and extension of the spine proceed in an orderly fashion, and undoubtedly long spinal fusions to the lumbar regions disturb these relationships [8,26,27]. What effects theoretically could such increased stresses bring to the vertebrae? The demand of increased excursion could lead to facet arthropathy, to early degenerative changes to the annulus and nucleus propulsis. Foramina stenosis from osteophyte formation or true canal stenosis could lead to pain and limitation of function. Activity induced back pain, or leg pain with or without neurological symptoms could be the consequences of such pathological changes. What evidence in the literature exists today that would support the evidence that such changes are taking place? In addition, is there evidence that patients are unhappy with the degree of remaining motion of the spine following spine fusion? What evidence supports perceptions either of the patients or the parents, or the surgeons that there is evidence that the curve has increased in severity? 2. The Evidence Understandably, the longest follow up of instrumented spinal fusions for idiopathic adolescent scoliosis has been with the first generation Harrington rods [5,12,20,22]. Cochran and Nachemson [22] have shown that in a follow up study of patients undergoing Harrington rod fusion to the L2 or L3 level that there was retrolithesis in 14 of the 24 patients followed. One hundred per cent of the patients had complained of some form of back pain, and ten per cent had loss of lumbar lordosis. Looking at other aspects of the consequences of surgical intervention,

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Danieisson [11] reported of a comparison of two groups of patients who had undergone either brace treatment or surgery. The age of the patients at follow up was at least 40 years old. The study specifically studied the effects on childbearing curve progression, and sexual function. They found equal rates between the two groups, with respect to the number of children born, cesarean sections, and sexual dysfunction. Back pain was present in 35% of those fused, in 43% of those braced, and 28% a normal comparison group. The presence and location of back pain in patients previously treated with Harrington rods 21years ago were assessed by Dickson [12]. Eighty-three percent of 206 patients responded, and were compared to a control group. The incidence of lumbar back pain was equal in the two groups, where as in the thoracic region the incidence of pain was greater in the fusion group. In a study of 1st generation fusions in 83 patients followed for an average of 10 years duration who had had the fusion extended into the lumbar spine L3, L4, or L5, Connolly [7] showed that patient satisfaction was high, ranking 81 out of 99 possible points. As a result of a questionnaire, 35 patients were rated as excellent, 20 good, 13 fair, and 15 poor. However, 76% had back pain verses 50% back pain occurring in a control group. Analyzing the changes in trunk balance following posterior spine fusion with Harrington rod and segmental wiring in King type II curves with a long term follow up average of 10 years, Frez found that the spine moved towards the midline, the shoulders leveled, and most importantly there were no incidences of junctional kyphosis [28]. In a recently published study form Sweden, Danieisson and Nachemson [15] reported on a consecutive series of 156 patients treated with Harrington rods, and 127 treated with bracing. Both groups were followed for at least 22 years and compared to a matched control group of patients. The surgically treated group had less lumbar lordosis that the brace group. Both of the treated groups had more evidence of degenerative changes in the control patients, though no statistically significant difference was found in the evidence of degenerative discs in those fused above L3 to those fused below L3. Edgar and Mehta [9] compared the ten-year results in 77 patients with Harrington rod instrumentation, to a similar sized control group of unfused scoliosis patients, and found that there was less radiographic deterioration of the curve, and less severe backache, and equal ability to do heavy work. The incidence of low back pain and cosmetic complaints was about equal in the two groups. There is evidence that in a group of patients studied preoperatively and postoperatively for back pain that there was an increase in back pain from 35% to 66%, and the increased incidence was more common if the fusion extended below the L2 vertebra [24]. The length of follow up of the use of the so-called 2nd generation rods is shorter. Humke [18] compared a group of patients fused using the classic Harrington rod technique followed for an average of 14 years to a group of patients undergoing Cotrel Dubuosset (GDI) instrumentation and fusion followed for 5 years. There was increased correction in the GDI group as well as less loss of correction postoperatively. The number of complications and the changes in the rib hump were equal in the two groups. The patient assessment of the two techniques on questionnaire showed no differences, however, of note was the fact that 40% of the patients with Harrington fusion had flat back, but none of the patients had symptoms accountable to this result. A retrospective review of the lumbar spine 10 years following the use of GDI instrumentation, Perez-Grueso found no significant differences in the radiographic outcome including changes on magnetic resonance imaging (MRI) to that of normal control, or what would be expected in the normal aging population [17]. Of forty-two patients studied pre and post operatively, Koch

M.S. More/and / <)nic(>iiit'.s of Scoliosis Fusion - Is Stiff and Straight Belter':'

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[29] found that on questionnaire 73% of the patients were satisfied with their outcome. Of the 27% of patients that were either neutral or negative in their assessment, the study showed that patients a higher proportion with lower body mass, were younger at onset of menarche, had a greater number of King type II or III curves, had a greater number of psychological issues preoperatively, and had higher number of unmet needs than the satisfied group. Several studies have supported the overall satisfaction of patients with their operative results when evaluated on questionnaire [4,21,29]. In a six-year follow up of patients undergoing Cotrel Dubousset instrumentation, Lenke [23] found a 100% fusion in the 75 patients studied, and only one patient with junctional kyphosis. Seventy three percent of the patients were evaluated using the Scoliosis Research Society Outcomes Instrument, and 38% complained of back pain. In a 12 year follow up of patients treated with instrumentation and fusion into the lumbar, Luk [14] found that 50% of the patients had junctional kyphosis at the caudal end of the fusion, though none had symptoms. They did note, however, that the remaining unfused segments showed hyper-mobility suggesting early degeneration of the disc spaces. There was no correlation between the clinical outcome and the radiology findings. Evaluating radiographic outcomes as seen in short-term corrections, may not always be perceived as clinically important by the patients [16]. It was not the purpose of this workshop review to be exhaustive, since the literature is replete with reports of outcomes following spinal deformity surgery. Haher [3] has written the most complete analysis of this subject. In this extensive meta-analysis of nearly 11,000 patients reported in 139 studies in the English literature written over a 35 year period with an effective follow up period of 6.8 years, it was found in part that: (1) 87% of the studies were retrospective, (2) That the best correlation with patient satisfaction seemed to be the absolute amount of correction achieved by the surgical intervention, (3) There was no correlation with the percent correlation, the degree of the starting curve, the type of King curve, prevention of progression, or the pulmonary outcome. 3. Discussion The issue of potential mechanical and structural problems occurring in spines previously fused for spinal deformity has been raised in this paper. The suggestion was made that because of the presence of a long non-flexible segment interposed in the middle, there would be negative consequences in the form of stress related degenerative changes. The presumption is that if such changes were to occur they would produce symptoms in the form of either perceived limitation of function or pain in the patients when studied in the long term. A brief review of the literature on long term follow up has not supported the findings of evidence of a significant increased pain pattern or significant complaints of limitation in flexibility or function in patients as revealed in retrospective studies involving outcome questionnaires. On the surface this might seem somewhat surprising, but compared to the studies that are in the literature of the outcomes of patients with untreated scoliosis [1,2] that have shown that even in significant scoliosis pain may not always be a significant symptom there does not seem to be a significant problem to date. The real issue, however, is what constitutes long term. Currently, the longest-term follow up studies are approaching 40 years, with patients now in their late forties and early fifties. What will be the effect over the next 20 years, when more significant generalized

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degenerative changes may be expected to occur? Therefore, it would appear that for the most part "straight" is better as perceived by the patients, and "stiff1 does not yet seem to be a problem. But we recognize the responsibilities of surgeons and scientists to continue to look closely at the outcome of our therapeutic endeavors for the first sign that problems are arising since the lag time for correction if problems were to occur would be significant. Similarly, surgeons and scientists must continue to investigate means of stabilizing the spinal deformity or correcting it by maintaining a more physiological approach in the treatment. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

12.

13. 14. 15. 16. 17. 18. 19. 20. 21.

F. Montgomery and S. Wiliner, The Natural History of Idiopathic Scoliosis. A Study of the Incidence of Treatment. Spine. 1988 Apr;13(4):401-4. 5. Weinstein, Adolescent Idiopathic Scoliosis: Prevalence and Natural History. Instr Course Lect.-1989;38: 115-28. T. R. Haher etal., Meta-Analysis of Surgical Outcome in Adolescent Idiopathic Scoliosis. A 35Year English Literature Review of 11,000 Patients. Spine 1995 Jul 15;20(14): 1575-84. D. Parsed, et ai.The Effect of Spinal Fusion on the Long-Term Outcome of Idiopathic Scoliosis, A Case-Control Study. J Bone Joint Surg Br. 2001 Nov;83(8): 1133-6. A. J. Danielsson, et al., The Prevalence of Disc Aging and Back Pain After Fusion Extending into the Lower Lumbar Spine. A Matched MR Study Twenty-Five Years. Acta Radio). 2001 Mar;42(2): 187-97. G.Monticelli, E. Ascani, V. Salsano, Analysis of the End Results of the Surgical Treatment of Treatment of Idiopathic Scoliosis, Isr J Med Sci. 1973 Jun;9(6):823-36. P. J. Connolly, et al., Adolescent Idiopathic Scoliosis. Long-Term Effect of Instrumentation Extending to the Lumbar Spine. J Bone Joint Surg Am. 1995 Aug;77(8): 1210-6. M. Harada, et al., Cineradiographic Motion Analysis of Normal Lumbar Spine During Forward and Backward Flexion. Spine 2000 Aug I ;25(15):1932-7. M. A. Edgar and M. H. Mehta, Long-Term Foilow-Up of Fused and Unfused Idiopathic Scoliosis. J Bone Joint Surg Br. 1988 Nav;70(5):7l2-6. R. B. Winter, Treatment of the Adult with Scoliosis. Minn Med. 1984 Jan;67(l):25-9. [11] A. J. Danielsson, et al, Health-Related Quality of Life in Patients with Adolescent Idiopathic Scoliosis: a Matched Follow-Up at Least 20 Years After Treatment With Brace or Surgery. Eur Spine J. 2001 Aug;10(4):278-88. J. H. Dickson, W. D. Erwin, D. Rossi, Harrington Instrumentation and Arthrodesis for Idiopathic Scoliosis. A Twenty-One-Year Follow-Up. J Bone Joint Surg Am. 1990 Jun;72(5):678-83. J. H. Dickson, etal. Results of Operative Treatment of Idiopathic Scoliosis in Adults. J Bone Joint Surg Am. 1995 Apr;77(4):513-23. K. D. Luk, et al, The Effect on the Lumbosacral Spine of Long Spinal Fusion for Idiopathic Scoliosis. A Minimum 10-Year Follow-Up. Spine. 1987 Dec; 12(10):996-1000. A. j. Danielsson, A. L. Nachemson, Radiologic Findings and Curve Progression 22 Years After Treatment for Adolescent Idiopathic Scoliosis: Comparison of Brace and Surgical Treatment with Matching Controls of Straight Individuals. Spine 2001 Mar 1;26(5):516-25. L. P. D'Andrea et al, Do Radiographic Parameters Correlate with Clinical Outcomes in Adolescent Idiopathic Scoliosis? Spine 2000 Jul 15 ;25( 14): 1795-802. F. S. Perez-Grueso et al, The Low Lumbar Spine Below Cotrel-Dubousett Instrumentation: Long Term Findings. Spine 2000 Sep 15;25(18):2333-4. T. Humke etal, Cotrel-Dubousset and Harrington Instrumentation in Idiopathic Scoliosis: a Comparison of Long-Term Results. Eur Spine J. 1995;4{5):280-3. D. C. Bean, Patients Who Had Corrective Surgery for Idiopathic Scoliosis. J Rehabil. 1980 JanMar;46(l):38-41. I. Helenius, et al, Comparison of Long-Term Functional and Radiologic Outcomes after Harrington Instrumentation and Spondylodesis in Adolescent Idiopathic Scoliosis: a Review of 78 Patients. Spine. 2002 Jan 15 ;27(2): 176-80. 5. F. White et al, Patients' Perceptions of Overall Function, Pain, and Appearance After

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23.

24. 25.

27. 28. 29.

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499

Author Index Ahmed, E.-N. Apostolou, T. Aronsson, D.A. Arvaniti, A. Asher, M. Aubin, C.-É. Aujla, R.K. Aulisa, A.G. Aulisa, L. Badger, G. Bagnall, K.M. Bakaloudis, G. Bashiardes, S. Bazzarelli, M. Beausejour, M. Bellefleur, C. Benameur, S. Benfield, D. Berg, D.C. Bhargava, R. Bibby, S.R.S. Bonioio, A. Brooks, W.J. Burton, D. Burwell, R.G.

162,173 104

97 47 153,369,462,469,486 54,130,144,309, 393,438,448 119,246,262,473 405,412 81,412 167 1,229,235,300 442 86 383 130,272 257 281 397 178,481

229,235 419 123 365 153,369,462,469 12,15,32,119,246, 262,473 Chadziargiropoulos T. 20 267 Champain, N. 140 Charlebois, M. 257,272,296 Cheriet, F. 162,173 Chokalingam, N. 438 Chopin, D. 104,433,454 Christodoulou, A. 114 Chung, M.A. 178 Church, T. 167 Churchill, D. 130 Ciolofan, O.C. 162,173 Cochrane, T. 119,246,262,473 Cole, A.A. 300 Currah, R. 336,348 Czernicki, K. 149,156 D'Amico, M. 25 Dangas, S. 12,15,162,173,305 Dangerfield, P.H.

Dangilas, A. 7 Daniel, A. 1,229 Dansereau, J. 54,64,144,257,296,393 De Guise, J.A. 140,276,281,286,291 DeSantis, V. 81,405 Delorme, S. 272 Demianczuk, C. 1 Deschênes, S. 276 Di Silvestre, M. 442 Dimas, A. 325 Dimock, A. 97 Dmitrieva, G.P. 126 Dobosiewicz, K. 336,348,357 Dolynchuck, K. 1 Dove, J. 162,173 Dowling, F.E. 59,68,101,465 Drazetic, P. 438 Dretakis, E.K. 422 Dubousset, J. 267,428 Duke, K. 144 Dumas, R. 291 Duncan, N.A. 114 Dupuis, R. 267 Durdle, N.G. 194,383,397,401 Durmala, J. 336,348,357 Edgar, M. 372 Fairbank, J.C.T. 419 Feipel, V. 130,448 Fergadi, A. 47 Ferguson-Pell, M.W. 372 Fogarty, E.E. 59,68,101,465 Fomichev, N.G. 204,222 Gardner-Morse, M.G. 167,314 Ghanayem, A. 322 Giardina, F. 442 Giataganas, G. 318,320 Gibson, M.J. 190,199 Giourelis, B. 76 Godbout, B. 276 Godillon-Maquinghen, A.-P. 438 Goldberg, C.J. 59,68,101,465 Goutsaridou, F. 318,320 Greggi, T. 442 Griffiths, C.J. 190,199 Grimard, G. 54

500

Grivas, T.B. Grosso. C. Gwadera, J. Hackenberg, L. Hantzidis, P. Harder, J. Havey. R. Hawes. M.C. Hierholzer, E. Hilang. E.M. Hill.D.L.

20.25.47.71.76 123 97 184,241 454 64 322 365 184,241 235 178.194,378.383. 397.401.477.481 322 Hodges. S. 229 Huang, E.M. 140 Huot. M.-P. 90, 135 Inoue. M. 318.320 losofidis. M. 90, 135 Isobe, K. 64 Jaremko, J.L. 336.348.357 Jendrzejek. H. 229 Jiang. H. 144 Joncas. J. 25 Kandris, K. 7.10 Kapetanos. G. 126 Karganov. M.Y. 37 Karski. T. 211 Khanaev. A.L. 126 Khlebnikova, N.N. 10 Kimiskidis, V.K. 114 Kimm. M.H. 489 King. A.G. 1 19.246.262.473 Kirby. A.S. 361 Kitagawal. T. 90 Kitahara, H. 144.257 Koller. A. 109.325.457 Korovessis. P. 90, 135 Kotani. T. 251 Kotwicki. T. 71 Koukos. K. 71 Koukou. U.I. 109 Koureas. G. 126 Kovaleva. O.I. 126 Kozhevnikova. M.I. Labelle, H. 54.64, 130, 140, 144, 257, 272 .281.296,393,448 393 Lacroix. M. 428 Lafage, V. 393 Lafon. Y. 462.469 Lai. S.M. 229.235 Lambert. R. 325, 457 Lambiris. E.

Landa, S.B. 126 Laporte. S. 286 Lark, D. 153 Lavaste. F. 428 Le Bras. A. 286 Lepoutre, F.-X. 438 Liljenqvist, U. 241 Lou, E. 378.383.397.401 Lovett. M. 86 Lucas. B. 153 Lupparelli. S. 81,405,412 Macdonald, A.M. 190,199 Mac-Thiong, J.-M. 140.448 Maffulji, N. 162 Mahood, J. 1.229..235.300.378.477.481 Mamyama, T. 361 47 Manesioti. M. Manna, B. 462.469 7 Markou. K. Maruta. T. 90,135 Mastantuoni. G. 405,412 130 Mathieu. P. A. 114 Matyas. J.R. 25.47.71 Maziotou. C. 81,405 Mazza. O. McArdle. F.J. 190,199 153 Mclff. T 419 Meir. A. 318,320 Melidis. D. 281 Mignotte, M. 204,211,216 Mikhailovsky. M.V. 90,135 Minami. S. 286,291 Mitton, D. 59,68,101,465 Moore. D.P. 477.481 Moreau, K. 1.229.235.300.378. Moreau. M. 401.477.481 492 Moreland. M.S. 318,320 Morichovitou. A. 90,135 Moriya. H. 372 Morley. T. 267 Mouilleseaux. B. 119,246,262,473 Moulton, A. 361 Nakainura. K. 90,135 Nakata. Y. 123 Negrini. A.Æ. 123 Negrini. S. 1 Nette. F. 372 Nicholson. G.P. 135 Nishikawa. S. 126 Noskin. L.A.

501

216 Novikov, V.V. 272 Novosad, J. 90 Otsuka, Y. 318 Papastergiou, Ch. 457 Papazisis, Z. 281 Parent, S. 442 Parisini, P. 322 Patwardhan, A. 322 Paxinos, O. 296 Pazos, V. 393 Périé, D. 81,412 Pitta, L. 357 Pius, W. 433,454 Ploumis, A. 272 Poirier, S. 81,405,412 Pola, E. 20,71,76 Polyzois, B.D. 76 Polyzois, D. 267 Pomero, V. 64 Poncet, P. 7,10 Potoupnis, M. 7,433 Pournaras, J. 32,119,246,262,473 Pratt, R.K. 162,173 Rahmatalla, A. 229,235 Rajwani, T. Raso, J. 1 ,300,383,397,401,481 Raso, V.J. 178 ,194,229,235,378,477 257 Remaki, L. 109 Repanti, M. 149,156 Roncoletta, P. 64 Ronsky, J. 448 Rooze, M. 300 Salvador, S. 20,25,76 Samelis, P. 204,211,216,222 Sarnadskiy, V.N. 342 Schaar, H.J. 114 Seek, C.S.

Secretan, C. Simonds, J. Skalli, W. Smith, K. Soonawalla, T. Spanos, G.P. Steib, J.P. Stokes, LA. Stratilati, S. Symeonides, P.P. Szappanos, L. Takahashi, K. Takaso, M. Takeshita, K. Tamaki, T. Tapsis, K. Terzidis J. Terzidis, I. Tonseth, K.A. Tsitouridis, I. Urban, J.P.G. Veile, R. Veldhuizen, A.G. Verniest, F. Vilberger, S.Y. Villemure, I. Voronov, L. Wang, X. Webb, J.K. Weiss, G. Weiss, H.-R. Wever, D.J. Wise, C. A. Zernicke, R.F. Zidrou, C.

235 322 140,267,276,281, 286,291,428 372 194 332 291 97,167,314 318,320 10 86 135 90,135 361 135 454 433,454 104 387 318,320 419 86 387 438 222 54,114 322 1,229,300 32,119,246,262,473 342,352 342,352 387 86 64 433