Imaging of Pediatric Bone and Joint Trauma

Imaging ofPediatric Bone and Joint Trauma

Fabio Martino . Claudio Defilippi . Roberto Caudana (Eds.)

Imaging of Pediatric Bone and Joint Trauma

Foreword by Carlo Masciocchi

~ Springer

Editors Fabio Martino Radiology Department Policlinico - Giovanni XXI1I Hospital Bari, Italy

C laudio Defili ppi Pediatric Radiology Service Regina Margherita Children 's Hospital Turin, Italy

Roberto Caudana Medica l Imaging Service Milan, Italy

The contents of this book are based on : Imaging del trauma osteo-articolare in eta pediatrica. F. Martino, C. Defilippi, R. Caudana (Eds.) © Springer-Verlag Italia 2009

ISBN 978-88-470-1654-5

e-ISB N 978-88-470-1655-2

DOl 10.1007/978-88-470 -1655-2 Springer Milan Dordrecht Heidelberg London New York Library of Congress Control Number: 20 I0924122 © Springer-Verlag Italia 2011

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Foreword

The role of diagnostic imaging in the evaluation of fractures and soft-tissue injurie s in skeletally immature patients continues to evolve as the technique s increasingly enable detection and characterization of abnormalities and provide results that affect decisions about patient care. Written by the leaders in the fie ld, Imaging of Pediatric Bone and Joint Trauma answers the questions arising in the diagnosis of these cond itions, which are peculiar to patients who are still growing, and offers a valuable and comp rehensive tool to all those called to prevent the often disabling deformi ties that are secondary to these conditions, and may be observed in adults. The chapters are ideally divided into three parts, and offer an accurate, complete, and updated analysis of the different locations, mult iple lesions, and dramat ic consequences of these inj uries on other parts of the body. For its didactic value, the volume will certainly meet the requirements of the reader and will particularly appeal to radiologists who will turn to it during their daily work. My warmest congratulations go to the authors and co-authors for a book that will certainly be a great success.

Carlo Masciocchi Chief of the Departm ent of Radiology University of 1.,' Aquila Past-President of the European Society of Musculoskeletal Radiology (ESSR)

L'Aquila, October 2010

v

Preface

Acute and chronic orthopedic injuries in children are unique in term s of the mech anisms of inj ury, pathophysiology, and he aling. In fact , because of the dynamic state of growth and development, pattern s of skeletal injur y in children are frequently differen t in type and presentat ion from tho se in adults, and so oft en requ ire different diagnostic and treatm ent algorithms. The role of diagnostic imaging in the evaluation of fractures and soft-tissue injuries in skeletally immature patient s continues to evolve, as the techniques increasi ngly enable detect ion and characterization of abnormaliti es and provide result s that affect decision s about pati ent care. The aim of this volume is to use a practical approach to provide an up-to-date and comp rehensive text on the all important aspects of mu sculo skeletal trauma ima ging in childre n and adol escent s. Accide ntal trauma, chronic and sport-re lated injuries, birth fractures, and batt ered child are describ ed and illustrated, highl ighting corresponding features in ima gin g, and pro viding an overview of find ing s in the different anatom ical sites of the bod y. Rom e, Octob er 2010

Fabio Martino Claudio Defilippi Roberto Caudana

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Contents

Major Traumatic Bone and Joint Injuries: Overview F. Martino , L. Falcone , M. lndolfi, M. Matarazzo and G. Martino

.

1.1 1.2 1.3 1.4

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Development and Growth of Bones. . . . . . . . . . . . . . . . . . . . . . . . . . . Characteristics of the Growing Skeleton. . . . . . . . . . . . . . . . . . . . . . . Fractures and the Healing Process: Clinical and Radiological Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Typical Osteo-traumatie Lesions of the Immatur e Skeleton 1.5.1 Complete Fractures 1.5.2 Plastic Deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.3 "Torus"-type Fracture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.4 "Green-stick" Fracture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.5 Metaphyseal-epiphyseal Fractures (of the Physeal Plate) 1.5.6 Apophyseal Detachm ents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Imaging in the Follow-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 Fracture and/or Dislocation Reduction - Synthesis - Consolidation . I. 7.1 Growth Arrest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 The Role of Diagnostic Imaging 1.8.1 Conventional Radiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8.2 Ultrasonogra phy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8.3 Computed Tomography (CT) .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8.4 Magnetic Resonanc e Imaging Suggested Readings

2

Micro-traumatic Lesions Caused by Overuse: Overview C. Defil ippi, P. Pautasso and C. Faletti 2.1 2.1.1

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stress Fractures

I 3 6 7 9 10 12 13 14 14 21 24 24 27 28 28 29 30 31 32 35

35 37 ix

Contents

2.1.2 2.1.3 2.1.4 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.3 2.3.1

Osteochondro sis and Osteochondrit is Dissecans . . . . . . . . . . . . . . . . . Osteochondr itis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Chronic Lesions of the Physis The Upper Limb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Little League Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Osteochondro sis of the Humeral Condyle (panner Disease) . . . . . . . . Osteochondritis Dissecans of the Humeral Condyle . . . . . . . . . . . . . . Little League Elbow Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Osteochondritis of the Olecranon Apophysis . . . . . . . . . . . . . . . . . . . . The Lower Limb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Osteochondrosis of the Epiphyseal Nucleus of the Femur (Legg-Calve-Perthes Disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.3.2 Epiphysiolysis of the Epiphyseal Nucleus of the Femoral Head. . . . . 2.3.3 Osteochondritis Dissecans of the Femoral Condyle (Konig Syndrome) 2.3.4 Osteochondritis of the Inferior Pole of the Patella (Sinding-Larsen- Johansson Syndrome) 2.3.5 Osteochondritis of the Anterior Tibial Apophysis (Osgood- Schlatter Disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.3.6 Shin Splints 2.3.7 Osteochondritis Dissecans of the Talus . . . . .. . . .. . .. . . . . .. . .. .. 2.3.8 Osteochond ritis of the Calcaneal Apophysis (Sever Disease) .. . . .. . 2.3.9 Osteochondritis of the Apophysis of the Base of the Fifth Metatarsal (Iselin Disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.3.10 Osteochondro sis of the Head of the Second Metatarsal (Freiberg or Koehler II Disease) Suggested Readings

3

39 41 43 43 43 44 44 45 45 46 46 46 46 46 47 47 47 47 48 48 48

Osteoarticular Trauma in the Pediatric Age: Overview - Apophyseal Injuries M. Valle, A. Tagliafico, L. Oppezzi, N. Gandolfo, P. Toma and C. Martinoli

49

3.1 Introduction 3.2 Tendons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Pathophysiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3 Chronic Apophyseal Lesions Due to Tendon Traction . . . . . . . . . . . .. 3.2.4 Acute Apophyseal Lesions from Tendon Traction . . . . . . . . . . . . . . .. 3.3 Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Apophyseal Injuries Due to Ligament Traction . . . . . . . . . . . . . . . . .. Suggested Readings

49 50 50 52 53 56 64 65 67

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Contents 4

5

6

Major and Minor Pediatric Traumatic Musculotendinous Injuries E. Genovese, A. Leonardi, L. Callegari, M.G. Angeretti, M. Albrizio, E. Spano and C. Fugazzola

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Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.2 The Role of Imaging in Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Muscolar Lesions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 Muscular Distract ive Lesions . .. . ... . ... ... . ... . ... .. ... . ... . 4.3.2 Muscolar Contusions 4.3.3 Complications and Follow-up 4.4 Tendon Lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.1 Tendinop athy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.2 Insertion al Tendinop athies (Enthesopathies) 4.4.3 Bursitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.4 Tendinous Ruptures 4.5 Abnormalities of Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.1 Extra-articular Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.2 Intra-articular Ligaments Suggested Reading s

69 69 71 71 74 74 75 75 76 78 78 78 78 80 81

Traumatic Lesions of the Peripheral Nerves E. Paeeiani, F. Randisi, C. Orazi, M. Valle and C. Martinoli

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5.1 Introduction 5.2 Ultrasound Scanning 5.3 Magnet ic Resonance Imaging Suggested Readings

83 84 89 95

Imaging of Regional Injuries: The Axial Skeleton - the Skull, Vertebral Column, and Thoracic Cage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Fonda, M. Mortilla, C. Cesarini and M. Basile

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6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.2 6.2.1 6.2.2

The Skull Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Orbital and Nasoethmoid Fracture s . . . . . . . . . . . . . . . . . . . . . . . . . . . Maxillofacial Fractures Mandibul ar Fracture s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zygom atic and Maxillary Fracture s . . . . . . . . . . . . . . . . . . . . . . . . . .. The Vertebral Column Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiological Examination

97 97 103 105 107 108 108 108 109

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8

Contents

6.2.3 Evaluation of Spinal Trauma 6.2.4 Pathophysiology 6.2.5 Superior Cervical Spine Injuries 6.2.6 Occipito-atl anto-axiallnstability 6.2.7 Odontoid Process Fractures 6.2.8 Extension Fractures of the Atlas and Axis. . . . . . . . . . . . . . . . . . . . .. 6.2.9 Flexion Trauma of the Inferior Cervical Spine 6.2.10 Extension Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 I Fractures of the Thoracolumbar Spine. . . . . . . . . . . . . . . . . . . . . . . .. 6.3 The Thoracic Cage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.3.1 Chest Wall Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Suggested Readings

I 10 112 114 114 115 I 17 117 I 19 I 19 12 I 121 123

The Upper Limbs D. Barbuti, E. Pacciani , M. Cirillo, A. Magistrelli and L. Tanturri De Horatio

125

7. I The Shoulder and Arm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7.2 The Elbow and Forearm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7.3 The Wrist and Hand Suggested Readings

125 13 I 146 ISO

The Pelvis and Lower Limbs D. Barbuti, E. Pacciani, A. Magistrelli, M. Cirillo, F. Fassari and L. Tanturri De Horatio

lSI

8.1 The Pelvis, Hip, and Femur 8.1.1 Fractures of the Pelvis 8.1.2 Sacro-coc cygeal Fractures 8.1.3 Traumatic Luxation of the Hip in Children . . . . . . . . . . . . . . . . . . . .. 8.1.4 Fracture s of the Femur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8.2 The Knee and Leg 8.2.1 Fractures of the Distal Epiphysis of the Femur 8.2.2 Fractures of the Patella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8.2.3 Fracture s of the Tibia .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8.3 The Ankle and Foot 8.3.1 Lesions of the Ankle Region 8.3.2 Fractures of the Foot 8.3.3 Fractures of the Astragalus 8.3.4 Fractures of the Calcaneus 8.3.5 Fracture of the Scapho id 8.3.6 Lisfranc Fracture 8.3.7 Fractures of the Metatarsals and Phalanges Suggested Readings

lSI 152 158 159 160 164 164 166 166 169 169 173 174 174 175 175 176 177

Contents 9

10

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Birth Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 C. Defil ippi, B. Santoro and P. Pautasso Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 9.2 Obstetric Pseudo-paralysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 " Birth Fractures" Suggested Readings

179 179 180 182

Toddlers' Fractures C. Defil ippi, B. Santoro and P. Pautasso

183

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 10.2 The Concept of Toddlers' Fractures. . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 Imaging Suggested Readings

183 183 184 186

Bony Lesions from Non-accidental Trauma C. Defil ippi, B. Santoro and P. Pautasso

187

11 .1 11 .2 11.3 11.4

187 187 190

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The " Battered Child": Imaging Fractures in Specific Anatomic al Sites Fractures in Non-specific Anatomic al Sites, with Particular X-ray Characteristics for Dating of Fractures 11 .5 Fractures with Particular Radiographic Characteristics . . . . . . . . . . . . 11 .6 Differential Diagnosis 11 .6.1 Defective Osteogenesi s 11 .6.2 Infantile Cortic al Hyperosto sis (Illness of Roske-De ToneCaffey-Silverman) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 .6.3 Dysmetabolic Bone Disease of Premature Infants 11 .6.4 Menkes Disease 11 .6.5 Rickets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 .6.6 Congenit al Syphilis 11.6.7 Scurvy Suggested Readings 12

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191 193 196 197 198 199 200 200 20 I 202 202

The Battered Child: Guidelines and Medical-legal Implications . . . . . . . . . 203 M. Solarino and B. Solarino 12.1 Introduction 12.2 Current Regulations and Medical-legal Considerations 12.3 Conclusions References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Suggested Readings

203 206 207 208 208

Contributors

Maria Gloria Angeretti Departm ent of Radiolog y Circolo Hospital Macch i Foundation Varese, Italy

Claudio Defilippi Pediatric Radiology Service Regina Margherita Children's Hospital Turin, Italy

Domenico Barbuti Department of Diagnostic Imaging Pediatric Hospital " Bambino Gesu" Rome, Italy

Lorenzo Falcone Radiology Department Policlinico - Giovanni XXlll Hospital Bari, Italy

Massimo Basile Department of Pediatric Radiology Children's Hospit al Meyer Florence, Italy

Carlo Faletti Department of Radiology AOCTO Turin, Italy

Leonardo Callegari Department of Radiology Circolo Hospital Macchi Foundation Varese, Italy

Fausto Fassari Department of Diagnostic Imaging Pediatric Hospital "Bambino Gesu" Palidoro (RM) , Italy

Cecilia Cesarini Department of Pediatric Radiology Children's Hospit al Meyer Florence, Italy

Claudio Fonda Department of Pediatric Radiology Children's Hospital Meyer Florence , Italy

Marco Cirillo Departm ent of Diagno stic Imaging Pediatric Hospital "Bambino Gcsu" Rome, Italy

Carlo Fugazzola Departm ent of Radiolog y Circolo Hospital Macchi Foundation Varese, Italy

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Contributors

Nicola Gandolfo IM2S - Institut Monegasqu e de Medecine & Chirurgie Sportive Montecarlo , Monaco

Maurizio Matarazzo Orthop edic Departm ent Policlinico - Giovanni XXlII Hospital Bari, Italy

Eugenio Genovese Depar tment of Radiolog y Circolo Hospital Macchi Foundation Varese, Italy

Marzia Mortilla Departm ent of Pediatric Radiology Children's Hospital Meyer Florence, Italy

Mariantonietta Indolfi Complex Structure of Radiology "Valle d'Itria " Hospital Martina Franca (TA), Italy

Leila Oppezzl Department of Radiology University of Genoa Genoa, Italy

Anna Leonardi Depar tment of Radiolog y Circolo Hospital Macchi Foundation Varese, Italy

Cinzia Orazi Departm ent of Diagno stic Imaging Pediatric Hospital " Bambino Gesu" Palidoro (RM) , Italy

Andrea Magistrelli Department of Diagnostic Imaging Pediatric Hospital "Bambino Gesu" Rome, Italy

Enzo Pacciani Department of Diagnostic Imaging Pediatric Hospital " Bambino Gesu" Palidoro (RM), Italy

Davide Mariani Department of Radiology Circolo Hospital Macchi Foundation Varese, Italy

Patrick Pautasso Department of Radiolog y AO CTO Turin, Italy

Fabio Martino Radiolog y Department Policlinico - Giovanni XXlII Hospital Bari, Italy

Francesco Randisi Department of Diagnostic Imaging Pediatric Hospital " Bambino Gesu" Palidoro (RM) , Italy

Gianluigi Martino School of Medicine University of Bari Bari, Italy

Bianca Santoro Pediatric Radiology Service Regina Margher ita Children's Hospital Turin, Italy

Carlo Martinoli Radiology Department - DISC University of Genoa Genoa , Italy

Biagio Solarino Section of Legal Medicine University of Bari Bari, Italy

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Contributors Michele Solarino Secti on of Rad iology " Fallacara" Hospital Triggi ano - Bari, Italy

Paolo Toma Department of Rad iology Ped iatric Hospital " Bambino Gcsu" Rome, Italy

Alberto Tagliafico Radiology Departm ent - DISC University of Genoa Genoa, Italy

Maura Valle Department of Radiology Istituto Scientifico "Gi annina Gaslini" Geno a, Italy

Laura Tanturri Department of Diagno stic Imaging Pediatric Hospital "Bambino Gesu" Rome, Italy

Major Traumatic Bone and Joint Injuries: Overview F. ~ Iarli no. L. Falco ne.

~ 1.

lnd olfl, F. ~ 1.

~ Ia laral.lo

1

a nd G. Ma r tino

1.1

Introduction

Du ring ch ildhood and adol escenc e, urgent osteo- articul ar trauma tic pathology is a fr equ ent occurrenc e, and constitutes on e of the main ca uses of dem and fo r med ical care in the emergency dep artment of a pediatric ho sp ital (more than 15-20% of all vis its ). Injuri es cau sed by skeletal trauma dur ing ch ildhood occur more than in adulthood, although in most cas es the extent of anatomica l damage is mod est. Mal es ar e affected mo re often than female s. In a lmos t 50% of cas es traum a is due to a fall and , in these cases, elbow and wri st fractures are the mo st common injuries. Carpal fractures, however, are uncommon lesion s in ch ildren and, when present , almost always invol ve the sca phoi d. Traumat ic bon e and joint inj uries in ch ildren differ from those in the adults in the range of ana tomica l fe atures, as well as biomechanical and phy siological as pects that ar e related to skeleta l growth and are strong ly influenced by endocrine-metabolic fa ctors (growth hormone, th yro xin , es trogens, testo sterone) act ing particularly on the growth cartilage . In addition to their effect on how the ana tomic dam age occurs, the se features may affect the healing time and bone remodeling, and can le ad to deformities when inj uries are not promptly diagnosed and properly treated. It is also important to remember th at a fracture during the growing years can result in an overgrowth of the bone involved, res ulting in hype rmetria, mo st frequently at the expense of the femur and humerus, due to the increased blood flow in the inj ure d area re lated to the rep air process . Not only do traum at ic injuries of the immature skeleton vary when compared with an adult, but ther e are also differenc es related to the age of the child or adolescent,

F. Martino (C8J) Radiology Department, Policlinico - Giovanni XXIII Hospital, Sari, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag ItaJia 20II

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becau se of the continuo us ana to mica l and biom echanical cha nges during the growing period, and becau se of th e wide variati ons in lifestyle dur ing different stages of growth. For example, fractur es of th e cla vicle an d femoral diaph ysis are fre quent in early childhood, while th ey becom e unu sual in adolescence, when the mo st affecte d anatomical site is th e distal end of the rad ius. Fractur es of the upp er limb in chi ldre n are th ree times mor e frequent than tho se of the lower limb , but thei r re lative importance increases after adolescence, especially in mal es, and inj uries are oft en related to the pra ct ice of sports (especiall y footb all , skiin g, and rugby). The same consi de rations apply to dislo cat ions, whic h are generally far less frequent than fract ures in those of a developm ental age . The reas on is related to the presen ce of an area of weakness, re prese nte d by th e growth car tilage plate, which is mor e vulne rable than tendons and ligam ent s befo re a capsular- ligament inj ury may occur. Since clo sur e of the physis occurs at different ages in different bon e segments, it is not uncommon to detect a dislo cated elbow aft er th e age of 7 years, while a subluxati on of the hum eral physis will be detected abo ve th e age of 12 to 14 years, that is, aft er the corresponding hum eral physis is clo sed. As in adults, a traum atic injury in a developing chi ld may be link ed to a nonaccide nta l ca use ; suc h an occu rr en ce is pa rticularly important in th e pediatric pat ient as it can suggest the so-called "m altreatment syndrome" or battered chil d, with corr esponding specific medical-legal responsibilities that may invol ve the rad iologi st. Tra uma tic injuries in children unde r the age of 3 years should always be rega rded with suspicion and clo sel y ex amined by the rad iologist, as 5-10% of tr aumas in th is age group are not accidental, but are cau sed by malt re atment. Therefore, in cas es whe re the re is suspi cion of a non- accidental traum a, diagnostic inve stigation s should be address ed to sea rching for and repor ting inj uries that may be rel ated, with high speci f icity, to mistreatment (be at ing s and /or violent shaki ng). Multiple fractures on different skeleta l segments , often bilateral, with evidence of inj uri es in di fferent stages of repai r and with an intense and extensive perioste al rea ction, are among the lesion s that be st ch aracterize a typical radiographic example of battered chil d. The radiologi st mu st, howe ver, pay particular attention, to the differenti al diagnosis between malt re atment lesion s and injuries indu ced by intense osteopeni a, suc h as tho se oc curring in osteogenesis imperfecta, wh ich strongly predi spo se to pathological fra ctures, and, if not properly ass ess ed, can be con fused with a battered child case . Sometimes a pathological bone fracture can be an unexpected finding, shown by the radiological investigat ion as an occasional con sequence of a mino r traum a to a skeleta l segment that has been made fragile by the presence of a pre-ex isting foca l le sion (Fig. 1.1). Traum ati c inj ury of the skeleton in developmental age, therefore, can manifest itself in di fferent ways due to the man y possible cau ses, and also bec ause of the high vari ability of all fac tors that , taken together, influence the mode of onset , anatomica l features, and healing proc ess of a traumati c inj ury, as well as influencing the selection of diagnostic modaliti es and th erap eutic treatm ent.

1 Major Traumatic Bone and Joint Injuries:Overview

Fig.l .l Radiography of the right knee in frontal (a) and lateral (b) view. Pathologic fracture of the tibia on a large aneurysmal bone cyst. The injury resulted in a cortex expansion and thinning, which appears discontinuous on the antero-medial side and shows a pathologic fracture in the process of consolidation, associated with a fallen fragment sign

1.2 Development and Growth of Bones In the development and growth of bones, star ti ng in the womb, two types of ossification have been identified: indirect and membranous. Indirect ossification, which occurs in mo st bones of the skeleton and is typi cal of long bones, sta rts from a primitive cartilage outline developing in the embryo, progressing to a subsequent repl acement of the cartilage matrix with bone ti ssue , both superfi cially (p erichondral ossi fi cat ion) and int ern all y (endochondral ossifi cat ion). In membrano us ossification , bon es do not follow the patt ern of evolution and are creat ed dir ectl y from th e mesen chymal connect ive tissu e, without passing through a cartilage stage . An exce ption to th is pattern is the mandibl e, in which direct ossification tak es plac e near a cartilage support that do es not j oi n to the fin al bon e (man-

tle ossification). The long bones, as mentioned before, show an indirect ossification pattern, and are repres ented in the emb ryo by hyaline cartilage models cove red by per ichondrium, and confi gured in a diaph ysis with two end s, or epiphyses (Fig. 1.2) . During the seventh week of embryonic life , the chondrocytes, in the middle section of the di aphy si s,

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are rich in glycog en and ca lcif ied intercellular substance. Meanwh ile, at the surface , at the same level as the diaph ysis, the perichondrium acquires osteobl ast ic activity and depo sits th ick trab ecul ar bone tissue layers on the surface, thu s form ing a primitive diaph yseal bone pock et (Fig. 1.2a) ; therefo re, the per ichondrium becom es periosteum . Subs equ ently, around the tenth week, vascul ar infiltr at ions of the periosteum capillary networ k penetrat e and cross the bone sleeve, thu s creating the diaphyseal trophic foram en (Fig. 1.2b). The vesse ls penetrate the central part of the bone and then branch out , help ed by the erosive action on cart ilage calci fied by the chondroclasts (also derived, along with vess els, from perio steum) . At this stage, osteobl asts (also of perio steal orig in) place bone trabecul ae on the remai ning cartilag e, thus forming a medull ar y cavity in the central bone sleeve, containing blood vessels, some osteocart ilaginou s trab ecul ae, and hematopoi et ic stem cells. At this very early stag e, the epiphyses are still cartilaginous (Fig. 1.2c). In the later stages, due to the appositive osteoblast activity in the deep layer of the periosteum , the perichondral ossification increases the outer diameter of the primit ive diaphyseal pocket; on the other hand, the medullary cav ity osteocl asts erode the deeper layers of the sleeve, thus widening the cavity and maintain ing the thickn ess of the pock et. The activity of the osteobl asts and osteocla sts is different in different parts of the diaphysis and helps to determin e the shape and fin al depth of the medull ary cavity in each diaphy seal part. This then extends toward the epiphysis, along the long itud inal axi s of the bone , through the calcific ation and subsequent ero sion , created by chondrocla sts, which create long path s where vess els and cart ilaginou s trabecul ae run long itud inally. The development of the medull ary cavity toward the two extremes come s to an end near the growth plate , the so-ca lled physis, which thus defines the boundaries of the diaphysis (diaphysis literally means "between physis") and identifies the metaphy sis area (lite rally "close to the physis") . Throughout the growth phase of the bone , the physis, also known as conjugation cartil age , is where active prol iferation of cartil age on the oppo site side of the diaphysis occurs, along with endochondral ossification on the side facing the diaphysis, thereby providing furthe r growth in bone length . The two cartil aginous extremes of the bone growth , which lie beyond the physis, correspond to the epiph ysis (literally "a bove the physis") . During development, endochondral ossification nuclei appear in the epiphysis, follow ing the penetration of vascul ar chip s from the epiphyseal perichondrium, with subsequent depos ition of bone lamell ae, formation of spon gy bone , and exp ansion of the se nuclei toward the surfa ce of the epiphysis (Fig. 1.2d) . At the same time , a layer of subperichondra l cart ilage remain s on the epiph ysis surface, which proliferate s on one side and is graduall y replaced by bone tissue on the othe r side, contributing to the development of the epiphy seal growth nucleus. Once the bone is fully grown , the two ossifi cation fronts, diaphyseal and epiphyseal , invade the conjugation cartil age and merge , ending the growth in bone length . When ossific ation is complete, only a thin hyaline cartilage cap rema ins in the epiphysis, corre spond ing to the articular car tilage. It should be remembered, howeve r, that some epiph yses (for example, the hum eral distal epiphysis ) have more ossification nucl ei, which are separated from one another and remain separated for a long time by a thin layer of hyalin e car tilage, befor e they fuse completely. Ossifi cat ion of short bones occurs in a similar way to that of epiphyses .

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Fig. 1.2a-d Explanatory scheme of growth and indirect ossification of long bones

y.1 4·15 11·20

Fig. 1.3 Schematic illustration of the location of the epiphyseal and apophyseal growth nuclei of the appendicular skeleton. In black, the average age of onset, and in red the closure age of the corresponding physis

In flat bon es, direct ossi fi cation tak es place, where, in some area s of th e outline, the mesenchym e becom es rich in blood vessel s and cell s. Mesenchymal cells become ost eobl asts that synthesize bon e tissu e in whi ch min er al s ar e deposited. At th e sam e tim e, the perio steum shapes the fin al bon e with an appositional mechanism . It is crucial for the radiologi st to have knowledge of the different epiphyse al and apophys ea l ossi fic ation centers, their age of on set , and the clo sure time of the corresponding growth plate , in order to limit mistake s in diagnosi s and to avoid the need for radiographs of the contral ateral side (Fig . 1.3) .

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1.3 Characteristics of the Growing Skeleton Ana tomical and physiological characte ristics of the grow ing skeleton (which mainl y in fluence the biom echanics and cl inic al-p athologi cal expression of the typical traumatic lesion s in th e immature ske leton), concern both th e osteop erio steal pock et, and the cartilag inou s growth plat e, or physis, which are ab sent in adults (Fig. 1.4). In childr en, th e bone matrix has a lower den sity, becau se th e mesh in the spongy web is wide r and the compact bone has a greate r po rosity, with an incre ased pre sence and siz e of Haver sian channel s, and is richly vas culariz ed, resulting in lowe r elasticity but gr eater plasticity. Th is feature make s the bone yield mo re eas ily, so it is more likely to de form than to fra cture. The periosteal sheath is much thic ker (rel ative thickness) than in adults, but le ss ten acious, bec au se the surface of bone adhesi on has le ss-de veloped Sharpey 's fibers. The refo re, when the perio steum is exposed to traum a it easily di ssect s itself, but rar ely bre ak s. This feature results in a limit ation in both the propagation of the fracture (comminuted fractures are in fact le ss frequent) and the degree of its di splacement. This is also why some compound fractu res in a ch ild may be unr ecogni zed at an early stage, and a reparative bon e callus is onl y found some time lat er at th e site

Fig. 1.4 Anatomical scheme of the epiphyseal-metaphyseal portion of the growth bone

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of the earlie r trauma. Furthermore, as there is a very rich subp erio steal vascular network, a lesion invol ving the perio steum is usuall y accompanie d by an extensive hematom a. The cartilaginous growth plate, or physis, con sist s of a car tilaginous matri x located between the metaph ysis and the secondary oss ifica tion epiphyse al nucl ei, and is typ ical of childhood, as it is totall y absent in the mature skeleton . In relation to the biom ech anical prop erti es of cartilage, the physis repr esent s an area of weakness as it is mor e fragi le in the face of traum a, if compare d to the bon e, tendons and ligaments. This featur e mak es the presenc e of cart ilag e (both in the physis and in the tendon attachment to the apophysea l cartilag e) act as a shock-absorber for the musculoskelet al struc ture s, preserv ing them from harm , and focus ing the forc e of the trauma on itself. In fact , in childr en, and especially in adol escent s, an epiphyse al and/o r apoph yseal displacement is mor e likely to occur rather than a ligamentous injur y, as ligam ent s are much more resistant to tension or tor sion forces (2- 5 times) than the cartilag e. In the knee, for instance, epiphyse al displacement or apoph yseal avul sion (th at occur in adol escent s) may be cons idered, in some ways, to be the counterpart of inj ury to the cruciate ligament s that occurs in adults. For the same reason s, even a meniscal lesion is a rare event in pediatr ic knee trauma, and is generall y associated with the pre sence of a predi spo sing condition , such as a discoid meni scu s.

1.4 Fractures and the Healing Process: Clinical and Radiological Evaluation The pecul iar characteri stic s of the grow ing bone, and, ther efor e, the anatom ical and physiological differences between children's bon es and adults' bon es, mean that the prognostic assessment and choice of treatment for pedi atric fractures is often different from that for adults . Typically, pedi atric fractures rec over much mor e rapidly than in adults, which on one hand is an advantage, becau se of the lower time of immobiliza tion; but on the oth er hand it repr esent s a limit ation , because the time availabl e to correct an inadequate fracture reduction is shorter (8-10 days in adults, 3- 5 days in children). However, with skeletal trauma in a child there is a reasonable tol eranc e for misalignment s, as the activ e and continuous remod el ing of growing bon e enables rec overy from deformities that would be unacc ept able in adults. In fact , the younge r the patient is, the closer to the physis the frac ture is, and the mor e the frac ture angular deformity lies in the plane of mo tion of the near est art iculation , and so the great er the rec overy of defo rmities will be. The deformit ies that recover best from remod eling are angular ones; even deformities with part ial overlapping of the stumps, and tho se with shor tening of the skeletal segment can be repa ired by remod eling and compensated by the incre ase in length-growth activity of the bone, which usually take s place in the phy sis near the site of fractu re . In contrast, tor sion skeletal deformit ies are less well tole rated in a subj ect of developmental age than in an adult. The combination of the se characteris tics , of course, affects both the method used

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for the statement of diagnostic imaging, and the qual ity of information that must be derived from it. Clin ical and rad iological evaluation of each fracture in the pediatric patient must take into account the patient's age , fracture location and type, degree of displacement , and angle of the stumps. The child 50 age is one of the first and most important factors for assessing the type of treatment; reparative osteogenesis is, in fact , faster than in adults because of the thick periosteum layer, which has a strong osteogenic activity. As the periosteum gets thinn er and the subperiosteal vascular network decreases with advancing age , the speed of repair decreases as welI: in a newborn, fractures consolidate and re-ossify completely in about 3 to 4 weeks, while in an adolescent this takes about 12 weeks . Regarding the fracture location and its distance from the bone extremity, it must be remembered that as one approaches the conjugation cartilage, bone remodeling is more active , so that in children younger than 8-10 years , in the mid-di aphyseal area, it is important to minimize the misalignment and the angle between the stumps with the lesion, while in the metaphyseal area a certain degree of axial or angular deviation of the remaining stumps is also acceptable, since at that level bone remodeling is able to restore its own norm al alignment. The best tolerated angular deformities (and most eas ily recoverable from remodeling) are those in the same plane as the dominant motion of the nearest joint. The fracture type, degree ofdisplacement, and angle ofthe stumps should be evaluated with extreme care because on one hand it is true that the lateral or angular misalignment of the stumps (as we have already mentioned) is partly restored by the remodeling power of new bone growth (angul ar deformities of 15° to 25° in patients younger than 7 years , and up to 15° in patients under the age of 10 years are considered acceptable) ; it is also true , on the other hand, that any presence of torsional misalignment (not recoverable by remodeling) may result in significant developmental abnormalities of the joints where the site of fracture is interposed. The fracture type that is most vulnerable to a delayed fracture consolidation is a "green-stick" one, where the convex side of the bone is under tension and is thus less affected by the compaction pressure force of the fragments, which is an important stimulus to consolidation (Fig . 1.5). It should be noted, however, that consolidation delay and pseudoarthrosis are particularly rare events in children, apart from in cases of opened and infected fractures in older children. In the developmental years, re-fractures are also rare, as are cases of myositis ossificans and post-traumatic articular stiffness. Even in the case of apophyseal avulsions, it is important that imaging allows avulsion quantification, for its magnitude affects the therapeutic choice, which also depends on which apophyseal nucleus is involved. Avulsion of the apophyseal growth nucleus of the ischial tuberosity may, for example, be treated conservatively up to a displacement of 2 em, beyond which a surgical reduction with synthesis should be expected. In the case of avulsion of the growth nucleus of the medial epicondyle at the elbow, an indication for aggressive treatment is given by nucleus dislocation that is ~5 mm . From the above it is clear that the treatment of immature bone fractures (whose aim is obviously to achieve and maintain a satisfactory reduction avoiding complications and, in particular, growth arrest) is essentialIy conservative, since the young bone heals quickly and growth reshapes the majority of reduction defects.

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Fig. 1.5 Delay of consolidation of a "greenstick" fracture, in the middle third of the radius' diaphysis (arro w)

1.5 Typical Osteo-traumatic Lesions of the Immature Skeleton The anatomical peculi ar itie s of the immature skeleton, which make it different from the adult skeleton, are mo re pronounced in younger patient s, and gradu ally become less pronounced with the prog ression of skeleta l maturat ion . The increas ed bone plasticity (and elasticity) , which results in a gre ater absorption of the damaging force s responsible for the traum atic event , make complete rupture of the matrix bone in children a rar er event than in adults; therefore, different , incomplete fractu res type s are most commonly seen, and are typ ical of the developmental age but not of adults. Also, since ligaments are gene rally stronger than the opened physis, a low-energy traum a such as a distor tion that can cause a lig amen t injury in an adult, result s mo re frequentl y in a physeal fractu re in a skeleta lly imma ture indivi dual. Fina lly, as long as the physis is open , the presen ce of a relative lowresistance zone help s to ensure that disloc ations are extremel y rar e in children, particul arly in pre-adolescence. Childre n, therefore, present a wide variety of fractures, which no universall y recognized classi fi cation includes entire ly. In addition to comp lete fractures, which are also found in adults, there may be oth er types of fractures that are exclusive to and typical of childhood, such as (Fig . 1.6): plastic defor mation , "torus"- type compres-

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NORMAL

PLASTIC DEFORMATION

GREENSTICK FRACTURE

BUCKLE FRACTURE

Fig.1.6 Several types of incomplete fracture oflong bones, characteristic of the immature skeleton

sion fracture, "green-stic k" fract ure, and metaphyseal- ep iphyseal or apophysea l fractures, with or without deta chm ent.

1.5.1 Complete Fractures In children and adoles cents, complete fract ures are usually the result of high-energy traum atic event s, such as fall traum a or be ing run over by a car. Just as with adults , for complete ped iatri c fractu res the site should be described, as well as the possible displacement of the stumps, the numb er of fractures, and the progre ssion of the fracture line (which can be transver se, spira l, obl ique , lon gitud inal, or branched ). The or ient ation and the course of the fracture may sugg est the mech anism by which it took place . Complete fractures in children most frequently affect the diaphysis of long bon es. In transver se fractures , the fractu re line is perpendicular to the majo r axis of the bon e. Thi s type of fracture is typic al of adolescence and of stage II-Ill childhood, and may also involve the met aphysis. Transverse frac tures are usually the result of a direct impact or shear forces (Fig. 1.7). In obl ique fra ctures , the frac ture line is variously ang led (usually about 30° to 45 °) to the longitudinal axis of the bone. The fractu re is usuall y cau sed by axial overload ing forces or by shear forces simi lar to those determining a tra nsverse fractur e ( Fig. 1.8).

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Fig.l .7 Transverse complete fracture of the distal metaphysis of the radius, in frontal (a) and lateral (b) view; complete transverse fracture of the femoral shaft in frontal (c) and lateral (d) projection

Fig. 1.8 Anteroposterior (a), and lateral (b) radiograph of the radius, showing oblique fracture through the distal diaphysis; oblique fracture of the ulnar diaphysis, in anteroposterior (c) and lateral (d) view, with undisplaced fracture of the midshaft of the radius In spira l fracture s, the "spiral" fra cture line oc curs more freq uently in the di aphys is of th e long bone, and is caused by torsion forces rath er than direct forc es. These fr actures , though often du e to maltreatmen t, arc not un common in trauma caused by acc id ental fall with a blocked limb, as happen s, for exam ple, with spi ral tib ia fractures in toddl er s. On the oth er hand, humeral spira l fra ctures ar c highl y sus p ici o us for

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Fig. 1.9 Spiroid fracture of the femoral diaphyseal upper third, in frontal (a) and lateral (b) projection; tibia and fibula distal meta-diaphyseal spiroid fracture, in frontal (c) and lateral (d) projection

a non- accidental traum a cau sed by ill-t reatment, seconda ry to the application of torsiona l forces such as tho se occuring when a limb get s twi sted. It is not always possible on radiograms to distingui sh an oblique fracture from a spira l one , and the type of fracture that is detected may require additional projections (Fig . 1.9). In longitudinal fractures, the course of the fracture line follows the long axis of the bone. Thi s type of fracture, which can also prop ag ate in an oblique or spiral direction, occurs more frequently in adolescence and sta ge III childhood, when the bone diaphy sis undergoes a progressive maturation of its bone component. In comminuted fractures, the fracture line propagates in different directions, branching and cau sing multiple fragments of var iable siz e. The se fractures are rar e in ch ildren, but can occur during adolescence, part icul arly at the tibia.

1.5.2

Plastic Deformation Plastic deformation con sist of a stabl e bowing of the bon e, with no evide nt fracture, and occurs when the diaphy sis of an imm ature bone recei ves a bending stress from a longitudinal compress ion of such intensity and dur ation th at it exceeds the limit s of elasticity but is not suff icient to produce a frank fracture . This stable curvature is actua lly cau sed by micro-fractures that are not vi sible rad iogr aph ically, occurring on

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Fig. 1.10 Plastic deformation. a Schematic example; b plastic deformation of the radius with"torus"-type fracture (arrow)

th e concave side of the invol ved bon e. Plast ic deformation is mor e frequent at the for earm (uln a and radi us), where it restr ict s or even prevent s pronosupination movement s; it can also be seen (although to a lesser extent) at the level of the femur (in infants) or fibul a. It usuall y displ ays fracture at th e bon e adjacent to th e affected limb , and occasion all y it is associated with subluxation (di slo cation) of th e corresponding joint s. Som etim es it affect s both bon es of the skeletal segm ent involv ed. In some cases th ere is co- exi sting perio steum dissect ion with subpe riostea l hematoma form ation. If this occurs in a child und er the age of 4 years, or if the angle is less than 20 °, the deformity usuall y adjusts itself with growth . In oth er cases, pa rticularly when combined with a fracture or dislocation of the adjace nt bon e, the redu ction may be particularl y complicated or even impossible (Fig. 1.10).

1.5.3 "Torus" -type Fracture "Torus"-type frac tures are due to an exce ssive cur vature of the immature bone, produc ing a compression fracture on the side of the concavity . Usua lly they result from a fall on a hyperext end ed limb . They are determined more often at the level of the metaphysis, in the tran sitional region (from the metaphyseal bon e tissue to th e diaphyseal lam ell ar bon e), where th e compact bon e is th inner and the spongy bon e is bett er represented. Typicall y, th ey are manifested as a swelling of one or both sides

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Fig.l.ll "Torus"-type fracture a Schematic example. b, c Distal metaphyseal fractureof the radius, in frontal (b) and lateral (c) projection

of the cortex; hen ce the architec tura l comp arison with the "torus" is derived - that is, a compari son with the bul ge that separates the sha ft of a column from its capital. Such lesions mo st commonly affect the wrist and tibia metaph ysis (Fig . 1.11) .

1.5.4 "Green-stick" Fracture " Green-stick" fracture s, who se radio graph ic appearance resembles that of a green branch that is not fully broken , are dete rmined when bone flex ion exceeds its own endurance limits on the side of ten sion , namely the convex side. Typically the y result from indirect traum a such as a fall on an out stretched hand (on an extended arm) . These are incomplete fractures, with the fractu re line branching from the side of convexity with in the marrow, without reaching the cortex and the perio steum of the concave side, which , the refo re, remai ns intact although it may suffer a plastic deformation. The se fractures occur preferenti ally in the diaphyseal-metaphyseal forear m, although they can also be found at the clavicle level, in the leg and in other long bones. It is not unu sual to find a "green-sti ck" fracture in one of the fore arm bones and a complete fracture (or an incomplete "torus"-type fracture) on the other bone (Fig. 1.12) .

1.5.5 Metaphyseal-epiphyseal Fractures (of the Physeal Plate) Fractures of the metaphyseal-epiphyseal complex (incl uding the epiphysis, the growth cartil age plate , surrounded by the Ranvier osteo- fibrou s zone, and the met aphysis) are typica l in pedi atri c patients and are the equ ivalent of an adult ligament inj ury and/or (complex) met aphyseal-epiphyseal fractures. In the age of skeletal

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growth , es pecially in adoles cen ce, approxi mate ly 35 % of fractures invol ve th e ph ysi s mo re or less ex te nsively. In th ese les ions, involvem ent of th e cartilaginous growth plate can be pr eci sely ob ser ved, and can be divided, from a hi stological standpoint into four zones (Fig . 1.13). Sta rt ing from th e epi physis th es e are : I. th e germin al zone of res er ve cart ilage 2. th e zone of cartilage prolifer at ion 3 . th e zone of hyp er trophic ca rtilage 4 . th e zone of provi sional calc ifi cation.

Fig. 1.12 "Green-stick" fracture. a Schematic example. Radial distal metaphyseal "green-stick" fracture (arrow) and ulna "torus" (arrowhead) in frontal (h) and lateral (c) projection

Fig.l .B a Anteroposterior wri st radi ogr am , which indicates the radio-transpa rent bandwidthaspect corresponding to the physis of the radius (inset); b anatomical diagram of the carti lagin ous growth plate

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Zones I and 2, with the characteristic columnar arrange ment of chondrocytes, corres pond to germ inative activity of the physis, which indu ces cartilage prolife ration and ensure s the lengthening of the bone . Zone 3, with large swollen chondrocytes, corr esponds to the region where the chondrocyte s degene rate and meet the calcifi cation (zone 4) and ossific ation (metaphyseal bor der). The fi rst two areas, closer to the epiphysis, are ric h in car tilage mat rix and are therefor e mo re resis tant to mechan ical stress. The third zone, characterized by the presenc e of hypertroph ic chondrocytes, has less resis tance to both shear force s and flexion and traction . The fourth zone, closest to the met aphy sis (and made more durable by calcification) , is the reg ion with more resistance, between the cartil age on one side and the bone on the other, but it is weaker than the firs t two zones. Therefo re, the epiphysea l displacements concern zones 3 and 4 of the growth cartilage in particular. The traumatic mechan ism of this type of fracture also depend s on the child's age. In fact, as long as the epiphysis is cartilaginous, it works as a sort of shock-absorber, transmitting the forces directl y to the metaphysis, and involving only part of the physis. With advanci ng ossifi cation, the amortization characteri stics of the epiphysea l cartilage are gradually impaire d, and therefo re the forces are transmitted, in a concentrated manne r, to the physis, which , as already mentioned, is involved in almost 35% of immat ure skeletal trauma , with the incidence increasing with age (from 10% durin g childhood to 35% during adolesce nce). Over 75% of metaphyseal- epiphyseal fract ures present between the age of 10 and 16 years, with the exce ption of elbo w fracture s, which are more frequent between 3 and 6 years. The majo rity of fractures of the physis (over 80% of cases) are caused by cutting forces (tangenti al) or avulsion force s. Lesions of the physis by compre ssive forces are less frequent (less than 20%), becau se the porou s bone structure makes the metaphysis less resis tant than the growth plate to thi s kind of stress . In summa ry, in childhood, when the physis is thicker, cutting and avulsion forc es more frequently determine epiphyseal displacements, which in older children and adolescents are more often determined by a comb ination of shear and angular (torsion- distraction) forces . Near the end of growth , when part of the physis is more subtle or partially closed, intra-articular cutting forc es with or without angular forces most frequentl y cause metaphyseal- ep iphyseal ar ticular fractures. Instead, when a compressi on force is acting , it fir st results in a fracture of the metaphyseal region, and then prop agate s to the physis, damaging all layers. Although , as noted earl ier, the growth carti lage is weaker than the adjacent bone , fractures of the bone structures in children and adolescents are always more frequent than fracture s of the physis, due to the size and type of forces required to damage the physeal plate. Similarly, since children's tendons and ligaments are more resistant than the physeal plate, it is more likely that a tra uma will cau se an epiphyse al avulsion fracture (or a fracture of the apophysis) rat her than a rupture of the ligam ent (or tendon). The mo st vulnerable physcs, more often involved at the occurrence of a traumati c event, are those of the wrist and ankl e. The major complications of th is type of fractur e are arrested development and alterat ion of articular congruity.

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Fig.1.14 Schematic representation of Salter-Harris classification

If there is no damage at the germ in al layer of the carti lage cell s or at th e locoregion al vascularization , con solidation of a fracture of the growth plat e is ver y fast. A full restoration of the growth plat e occurs in about 3-4 weeks. The most commonl y used classification to encode metaphyseal- epiphyseal fractur es is that described by Salter and Harris (Fig. 1.14), which divides them into five types, and corr elates rad iological events, place, incidence and morbid ity, with each one. Type I follows an impact lesion of the physeal plat e, and is characterized by a tear of the growth cartil age along the horizont al plane , corresponding to the layer of hypertrophic or degenerated cell s, while the rest of the cartil age rem ain s supportive to the epiphysis, with a cross- slip of the epiphyseal nucleus. In the se fracture s, the per iosteum usually remai ns attached to the growth cartil age , thu s preventing a serious breakdown of the fractu re. If there is a minimal perio steal lesion , the only radiographic sign evident is a slight diastasis of the physis (Fig. 1.15). The se fracture s are more common in children youn ger than 5 years, when the physis is relat ively thick , with the exception of prox imal humerus fractures in which the peak age of incidence is between 10 and 12 years. The diagno sis is mainl y based on clini cal suspicion, eventually validated by the radiogr aphic demonstration of an epiphysis disloc ation (mo st often due to slipping, with or without physis diastasis). In doubtful cases, the diagno sis can be easily confi rmed by performing a magnetic res onance imaging (MRI) examination. Salter-H arr is type I le sion may also be minimal and take place without a recognizable epiphyseal displacement, thu s resulting in a negative radiogra phic inspection. In such cases, a new rad iographic evaluation, perform ed after an inter val of 8-10 days since the traum a, may have a positiv e result and may show the presence of a thin band of spongioscle rosis clo se to the physis, with irre gular appearance of the bord er of the physis (repairing side), orienting the diagno sis toward

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Fig.1.1S Salter-Harris type I fracture of the distal edgeof thetibia. a Schematic example; b contralateral healthy tibia; c, d physeal fracture, with mild epiphyseal separation, in frontal (c) and lateral (d) projection

th is type of fracture . The prognosis for the se fractures is good, even when they are displ aced, provided the re is a prompt reduction. Although thi s type of injury is not usually assoc iated with vascul ar di sorders, a complete det achment of the epi phy sis at the femora l proximal extreme may cause ischemic necrosis and growth arr est. Type II is character ized by the coexi stence of an incomplete fracture of the phy sis and a fracture of a met aphy seal edge (Fig. 1. 16). The injury mechanism generate s a viol ent bending stress in the metaphyseal-epiph yseal segm ent , resulting in perio steum inj ury on th e side subjecte d to traction forc es, with a tear in th e growth cartil age along the tran svers e plan e; the contextual angular displacement of the epiphysis, with rotation on th e point of flexion , induces an oblique deviation of the fracture plan e in the direction of the metaph ysis , inducing an angular detachm ent of the metaphyseal edge (Thurston -Holland sign). The perio steum is usuall y damaged on the involved sid e dur ing traction (site of lac eration and phy sis widening) , but it is intact on th e compression side, where the metaphyseal fragm ent is found (where the growth cartilage is intact). This type of fracture is mor e common at the di stal radius and phalanges, in chi ldren older than 10 years (Fig . 1. 17). In most cas es the reduction is not part icularly complicated and the prognosis is favor able . • In type III the re is incomplete growth carti lage plate injury combined with a vertic al and/or ob lique fra cture of the epiphyseal nucleus, with involvement of the cartilaginous lining of the articular surface (Fig . 1.18). On the side of the growth

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Fig. 1.16 Salter- Harris type II compo sed fracture. a Schem atic example ; b, c radial fracture (arrow) without stumps dislocation, in frontal (b) and lateral (c) projection

Fig. 1.17Salter- Harris type II displaced fracture. Fracture with dislocation of stumps of the base of the 4th toe proximal phalanx, in frontal (a) and oblique (b) projection

Fig. 1.18 Salter- Harris type III fracture. a Schematic example; b tibial distal epiphyseal fracture (arrows)

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Fig.l.19 Ten-year-oldpatient with angular varus deformity of the distal third of the lowerrightlimb, withshortening of the tibia, secondary to the formation of a transphyseal bone bridge (arrow) and focal growth arrest, resulting from Salter-H arris typeV misdiagnosed fracture

cartilag e tear, a metaph yseal- epiphyseal diasta sis is ob serv ed, as well as a dislocat ion (usu all y small) of the epiph yseal fragment, which is detach ed and mobilized from the metaphy seal surface, becau se of th e fracture. These qu ite rare lesion s are cau sed by int ra-articular shear force s (with or without the combination of angular forces) and they usually occur at the level of the prox imal and di stal tibia epiphysis. Arrest of growth and residu al bone deformities are rare event s, except in a case of non-reduced fractures. In type IV le sion s, the epiphyseal fracture line extends obliquely in a proximal direction, with a full-thickne ss growth cartil age lesion , reaching the met aphy sis, where it produces det achment of a bone 's edge . It is always rel ated to unstable fractures, which require appropriate tre atment. They are more common at the distal humerus and di stal tibi a level s. These are lesion s with the wor st prognosis, bec au se of involvement of the growth cartil age germinal layer, situated close to the metaphysis, and they may comprom ise the regul ar growth of the long bone . Typ e V le sions are the result of compression forces that affect the growth car tilage surface, more or less orthogonally, caus ing its destruction by crushing and/or cau sing serious damage to the loco-regional vascul atu re, but without invol vement of the ep iphyseal nucleus. These relatively rare lesion s are often loc ali zed at the femur, knee, and ankle level. As with type IV lesion s, phy sis imp act inj uries also constitute a high risk of a longitudinal foc al arr est of bone growth, with secondary de formity. Complete arr est of bone growth can result in a signif icant limb length di screpancy , with function al lim itations. Parti al arr est may cause an angular de formity (Fig . 1.19) or a progressive shortening. In the se cases, as in type I lesions, radiograph s may not be diagnostic, so if there is cl inical suspicion of a type V lesion , running an MRI survey is highly useful for both diagno sis and subsequent control s. The Salt er-Harris cla ssification was sub sequentl y extended by Ozonoff, Rang and Ogd en , with the assi stance of mor e careful study of lesion s using MRI , and four additiona l types were added (Fig. 1.20) :

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Fig. 1.20 Schematic representation of Salter- Harris additional fracture types (type VI, VII, VIII, and IX) according to Ozonoff, Rang, and Ogden

Type VI involves the perichondrium and the edge s of the physis, with reactive periostiti s loca ted out side the physeal plate . The secondary form ation of a bone bridge limit s and/or stops the physeal plate growth, resulting in a met aphy sealepiphyseal angulation. The se fractures are rare and are usually caused by a direct blow (direct traum a). Type VII only affects the epiphysis, without invol ving the physis. It is a rel atively frequent and important fracture, which , be ing a transcondral fracture, can affect the elbow, hip, knee , or ankle. Type VIII is an isolated fracture of the met aphy sis, which reduces the met aphysea l vascul arization and inte rfere s with the endochondral ossifi cation . Type IX affects the periosteum and the emergent membranou s bone.

1.5.6 Apophyseal Detachments The apophyses are bony outg rowth s onto which tendon s or ligament s inser t. In children and adolesce nts these apophyses are originally mad e up of cartilag e, which later become s the site of seconda ry ossification, until it reaches full development and fusion with the adjacent met aphy seal-epiphyseal bone . The apophyseal cart ilage side fac ing the teno chondral junction, con sists of growth cartilage, the so-called apophysea l physis (with a typ ical columnar arrangement of chondrocytes), on which tendons

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Fig.l.2l Schematic representation of the apophyseal tendon insertion in the growth skeleton

and ligament s insert via Sharpey 's fibers, which partl y continue in the perichondrium and are partl y anchore d directl y on it (Fig. 1.21). The apophyseal hyal ine cartil age is a weak point when traumatic insult occur s; therefo re, abru pt avul sion hyper- sol icitation , which usuall y spares tendons, lig aments , and bon e, can lead to cartilage fractures (a particularly weak area is between the growth nucl eus and the metaph yseal bon e) producing a detachm ent. Apophyseal det achments are more common in adoles cents engaging in sporting activiti es (or in oth er leisur e activi ties with inte nse phy sical stress, such as dancing) and mainly affect th e pelvis and the knee, since these are the most stressed part s in the most popular spor ts (football , tenn is, etc) as well as repre senting the locations with the highest numb er of apophyseal growth nucl ei compared to oth er ske letal sites (Fig. 1.22). In th e apophyseal detachment s, the instru menta l document ation uses both ultr asound and th e con ventional radiological examination in a comprehen sive way; in doubtful ca ses, MRI plays a definitiv e diagnostic role . As alr eady discu ssed, the pelvis and knee are the skele tal site s most commonly involved in apophysea l detachment s that, in ord er of frequ ency, affect : the ischi al tuberosity, the anterior superior ilia c spine (ASIS), the anterior inferior iliac spine (AilS), and the pubic symphysis at th e pelvic level, and the ante rior tibial tub ero sity and the tibi al spine at th e kne e level. Detachm ent of the ischia l tub eros ity is cau sed by a forc ed contracture (gymnastics, socce r, fencing, athl etics, etc) or by passi ve disten sion s (dance) of the ischial tibial mu scl es. Detachemnt of the ASIS , on which th e sartorius and tensor fasc iae latae mu scles insert, is caused by a forced hip extension, particularly in football players , sprinters, and jumpers. AilS det achment is secondary to a forced direct tendon hyperextension of the femur's stra ight muscle, as happens in the case of an "empty kick" with a posture of maximum hip flexion and knee extension (Fig . 1.23) .

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Fig.l.22 Integrated imaging depicting an apophyseal detachment of the growth nucleus distal portion from the left iliac crest (arrows ) in a 16-year-old injured football player. a Ultrasound; b conventional radiography; c CT

Fig.l.23 Sagittal ultrasound images (a) and CT (b) of AilS detachment (arrows) in an adolescent athlete

Pubi c sym phys is detachments ar e ca use d by sudden or rep eat ed fo rced adduction mo vements, involving the long and short adductor mu scles, which insert on the angular surfa ce of the pubis. Acute det achments of the anterior tibi al tuberosity (apophysea l fracture-detachments) ar e avuls ion of the anteri or tibi al apophyses, where the traum atic event is rep resented by a violent, active knee extension (football , rugby), or by its sudden passive flexion contrasted by a qu ad riceps mu scle contra ction (b asketball , volleyba ll, gym equipment). These det achments co rre spond to type I or III of the Salt er-Harr is cl assi fic ation, and are subj ect to a spec if ic thr ee-type cl assific ation sys tem as de scribed by Wat son-Jones and modified by Ogden. Det achments of the tibi al spine occur mo st frequently in children between the age of 8 and 14 years, and are the res ult of a knee hyperextension and extra rota tion trauma - an eve nt th at can ca use an ant erior cruciat e ligam ent rupture in adults . Bon e det achmen t alwa ys occurs in th e po sition of th e anteri or inte rcondy la r emi nenc e. Physical ac t ivities freq uently involve d in th is lesion are cycling and skii ng. Meyers and McK eever describ ed thr ee ma in types of intercondy lar fra cture.

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Physeal inj uries of the verte bra l bod y ca n also occur at the spine (at the gr owth cartilage/ring apophysis junction) , du e to the insertion of the anu lus periph eral f ibe rs (Sharpey's fi bers) in the apoph yseal sec ondary ossification point of the ver te bral soma.

1.6

Imaging in the Follow-up

The purpose of an imaging inve stigation at follow-up (immediate ly post-treatm ent) is to che ck the co rre ct fra cture reduct ion and/or disl oc ation, along with the co rrect po sitioning of the therapeutic material s. The goa ls of subseque nt im agings are to confirm that cons olida tion h as taken place and to veri fy the abs ence of any ass ociated unfavo rabl e evolution, the mo st important being di sturban ce of foc al growth, secondary to a circumscribed in sult that has dam aged the growth cartilage ; avas cular necrosi s; and septic complications.

1.7

Fracture and/or Dislocation Reduction - Synthesis - Consolidation

The reduction and synthesis of a fracture or di slocation usu all y need a radioscopic control , in orde r to gu ide the surgica l procedure during the intervention , and a radiogr aphic ass ess ment soon after the surgery, to veri fy th at the therapeutic treatm ent has been succ essful or that it needs fur ther correction s. After reduction , fra cture stabilization is ach ieve d by con servativ e treatment with cast immobili zation, or by me an s of surgica l procedure s of f ixa tion, depending on the stabi lity of the reduced frac ture (Figs. 1.24 and 1.25) .

Fig. 1.24 Femoral Salter- Harris type II distal diaphysis-metaphyseal fracture, in frontal (a) and lateral (b) view. c Radiographic postoperative control after fracture reduction and fixation through Kirschner wires. d Control after the removal of fixation devices, which allows visualization ofth e good fracture reduction in the process of consolidation

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Fig. 1.25 a Lateral radiograph of the knee, showing a Salter-Harris type II proximal metaphyseal displaced fracture of the tibia. b Image intensifier view of intra-operative control after fracture reduction by trans-skeletal traction. Radiographic control in A-P (c) and L-L (d) projection, in plaster with included tension wire. Radiographic control in A-P (e) and L-L (f) view, performed after removal of the plaster cast and traction wire, which allows visualization of the good reduction of the fracture in the process of consolidation

Th e con sol id ation and sta b iliz ati on process of th e fracture is ac hie ved with th e formati on of bon e ca llus . Initiall y, th e subpe rios teal fi brous callus sur rounds th e fracture, joining th e fragment s at th e top and th er eby pro vid ing th e best gu arantee for th eir immobil it y an d stabi liza ti on. Th e callus extensi on dep end s on th e exte nt of dislocation suffere d by th e stumps during traum a, becau se th e gr eat er th e d islocation, th e mo re exte nsive th e perio steum di ssect ion an d subsequen t hematoma will be. During th e growing age , th e per io steum is thi ck er an d more robust th an in adults, and rar ely br eak s. On th e con cave side of angulate d di spl aced fractures, the periosteum mo stly rem ain s int act (th is is useful for reduction maneuvers) , alth ough the pe rio ste al str ipping predominantly oc cu rs on thi s side . The radiological sign of a sta ble con solidat ion is given by the pre sence of a subperi ostea l calcified callus, which h as approx ima te ly the sa me den sity as the adjacent cor tica l bone (Fig . 1.26)

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Fig.l.26 Various stages of consolidation of a spiroid fracture in the middle third of the femoral diaphysis in a young patient aged 2 years. a Radiographic examination on the day of trauma; b the test performed after 18 days demonstrates the calcification ofth e subperiosteal callus; c the radiographic control 40 days after the trauma shows the initiated ossification of the perilesional callus

and is recogni zed in at least three out of four cortica l bone profile s represented in the A-P and L-L orthogonal projection s. Such a radiographic outline, combined with the absence of pain during palpation, can determine the success ful sta biliza tion of a fracture. The appearance of the callus below the lesion occurs later, and is manifested by the obliteration of the fracture line ; a "green-stick" type of fracture take s mo re time to rep air. The subs equent rep air is carried out through ossification of the calci fied callu s, whi ch requires a few months afte r the function al recovery, and later through remodeling, wh ich requires a few years. During growth, then, re sidu al deformitie s (tolerated stumps angle or callus exuberance) are reworked and remodeled to get clo ser to the or iginal morphological structure, helped by a reg ained phy siological function . A con solidation del ay is not common and usually occurs whe re there is little compression of the fragments, as may happen in insuffic iently reduced "green-stick" fractures, or in stumps angulation fractures with a le ss favorable orientation (an angular devi ation on the sagitta l plane is more recoverable than one on a co ron al plane , and generally a varu s devi ation is mo re favorable than a valgus one). The radiogr aphic control shows per sistence of the fracture line , on which the pre sence of a subperiostea l callus inte rruption is ob served (Fig. 1.27) . The se del ays in con sol idation represent weak points, and ca n induce a fracture recurrence within one year of the initial trauma. However, with the exce ption of tho se occurring at the elbow level, po st-traumatic pseudoarthro sis usually has a favor abl e prognosis in childhood and adoles ce nce .

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Fig. 1.27 Delay of consolidation in a proximal metaphyseal-diaphyseal fracture of the humerus with a mild valgus deviation and discontinuity of the subperiosteal callus on the medial side (arrows)

1.7.1 Growth Arrest Prem ature clo sure of the phy sis, with growth arrest and con sequent skeletal de formitie s, represents a feared and un favorable outcome of a trauma. Fortunately, thi s is a very uncommon event , which in most cases affects the knee and the ankle. In thi s situation, the physis is exception ally invo lved throu ghout its enti re extension , whereas a lesion usually only part ially affects the cartil age growth plate . The cartil age lesion may occur as a result of a cru shing destruct ion (Salter-H arr is type V) that is a te ar with a severe and irreparable loc ali zed vascul ar dam age (about 35% of cases in wh ich the re is stumps disloc ation) . Trauma -related severely damaged cartilage undergoes ossification, with form ation of a bone bridge between the epiphysis and the met aph ysis. In the place of inj ury, then, the bone has a foc al growth arre st where cart ilage dam age occurred, wh ile smooth growth take s pl ace , as usual , in the unharmed surr ounding bone. The res ult is an anomalous sha ping of the skeleta l segment, which lead s to an angular deformity in case s whe re the le sion is loc ated in a peripheral area . In mo st cases, con ventional radiography ca nnot detect the pre sen ce of the tran sphyseal bone bridge and, the refore, if there is th is diagno stic suspi cion, it is essential to complete the ass ess ment using either a CT, or, preferably, an MRI sca n conducted with appropriate sequences for the cart ilage study. Once the lesion has been diagnosed, treatment may incl ude tran sph yseal bone br idge resection, and the pro gno sis is good if the dam age invol ves less than 50% of the physis, and if there is sti ll a gro wth expe ctation of at least two years . Oth erwise, th e angul ar deformity can be correct ed by realignment osteotomy (Fig. 1.28) .

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Fig.1.28 a Varus angular deformity by growth arrest of the distal end of the left femur, secondary to fracture, subsequently subjected to metaphyseal osteotomy for corrective treatment of varus malalignment (b)

1.8

The Ro le of Diagnostic Imaging In the diagnostic pathway for pedi atric skeletal trauma, im aging plays a major role, th anks to the m any tool s ava ila ble today, although a conventional rad iograph ic appr oa ch is often suff icient and recommended. With re spect to ra diation protection for young patients, it is a good prem ise th at any radiographic ex amination shou ld be re served only for situa tions when it is abs o lutely essential for a proper di agno si s and/or it can influence the therapeutic stra tegy, or it is needed as a basic reference in the follow -up during tre atment. Th is obviously requires the radiologist to h ave a deep understanding not only of the use of diffe rent im ag ing modalities, but als o of the pathogen ic mechani sms and cl in ic al as pects of the di fferent patho logical patterns of pediatr ic tr auma, and po ssible interrelat ion ships with other coexi sting and predisposing pathologie s.

1.8.1

Conventional Radiology Conventio nal rad iology still represents th e fir st level of diagnost ic study of bone trauma, although it gives poor inform at ion about pe ri skeleta l soft ti ssue injury, espe ci ally if compared with ultrasound and MRI. A correctly performed radiologic study, however, allows an ove rall ev aluation of soft ti ssues, and ca n often show indirect signs of joint effu sion or hemarthro si s (such as the " sail sign" , an indirect si gn of an

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elbow occult fracture, determin ed by lift ing of th e hum eral coronoid fossa fat pad, due to ca psular distension cau sed by an intra-articul ar bleeding) . Recognition of fractures in childhood, more than in adults, requ ires at least two proj ections, usuall y in orthogonal plan es, allowing accurate determination of po ssible misal ignment and deformities that are liabl e to affect the therapeut ic treatm en t. It should be noted that standar d proj ect ion s are som etim es not abl e to show sma ll fracture lin es or fractu res localized in spe cific anatomical sites; so, where the doubl e A-P and L-L proj ect ion of th e radiologica l exami na tion is negative, but there rema ins suspicion of a lesion from th e pati ent 's clin ical evaluation, it is important to perform add itional proj ect ions, which will differ dependi ng on the ana tomi ca l region und er examination . It is also recommend ed that at least one of the two j oi nts corres ponding to the traumati zed bon e segme nt (p referabl y th e near est one and/or the mo st painful) are repr esent ed on the rad iogram. Wh ere trauma has occur red, th erefo re, the use of con vent ional radiology will be primarily directed to evaluating the major traum at ic injuries (fr ac tur es, epiphyse al and apophyse al displacem ent , d isloc ations) and their outcomes (dise ase of th e bon e callus, myositis ca lci f ication, etc ).

1.8.2 Ultrasonography Ultrasound invest igat ion is complem entary to con vent ional rad iology, and is eas ily avail abl e, at low cost, with th e ben efit of being free from ioniz ing rad iat ion . Ultrasonography pro vides a good repr esen tation of periskeleta l soft tissues, allowi ng clarification and/or conf irmation of suspec ted radiographically hidd en fractures ( Fig. 1.29), apophyseal det achm ents and th e apo physes (an exam ple is Osgood-Schl att er 's d isease) , which are mu ch mor e freque nt in a development al age than tendon or ligam ent injuries.

Fig. 1.29 a Negative confirmation of the radiographic control performed after blunt trauma to the skeleton rib. h On the basis of symptoms, an ultrasound check is performed focusing on the site of pain, which documents the rib fracture (arrowhead) , which was missed on radiological examination, and the corresponding parosteal hematoma (arrows)

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Furthermore, es peci ally in infants where the epiphyseal nuclei are not yet calcif ied, ult rason ograph y allows imme dia te and tho rou gh study of the carti lagi nous n ucle us and eva luation of any po st-traumatic dislo cat ion (for example, epiphyseal n ucle us av ulsi on) that conve ntional rad iographic inves tigati on may not be abl e to highli ght. Sup erfi cial hem atomas and intr a-arti cular depo sit are oth er pathological conditions that are easi ly diagnosed using ult rasonograph y. The use of color mod e and, in par ticular, power-Doppler, may also be advantage ous for bett er def inition of the events taki ng pla ce in the repa ir of ske let al mu scle injuries.

1.8.3

Computed Tomography (CT) Due to its large use of rad iat ion , th is is rare ly used in the eva luat ion of trauma in young pat ien ts, except in cases where the firs t-level investi gat ion s have not pro vided sufficient detailed in formation on the extent and seve rity of the injury (with exact definition of the number, size, and relation s between bon e fragme nts, and th e possible presence of loo se intra-artic ular bod ies) to enable prop er treatm ent to be und ertaken, such as during spina l injuries, complex pel vis and knee fractu res, or problematic osteo-arti cul ar circum stances (Fig . 1.30) . The advent of multi sl ice CT, with the po ssibil ity of multiplan ar and three-dimension al reconstruction s, has offered an additional perspec tive that is mo re helpful for the surgeon in the extensi on study and

Fig. 1.30 Salter-H arris type III proximal metaphyseal-epiphyseal fracture of the tibia and proximal diaphyseal, oblique and broken fracture of the fibula. a-c Radiographic control (a), CT in axial section (b) and in reconstruction in the coronal plane (c)

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the follow-up for complex traum atic lesion s, as it allows bett er planning of the therapeut ic inter vention, as well as early detect ion of development of possibl e defo rmities, or, in the case of extended growth cartil age fractures, premature clo sur e of the physis, res ulting in growth arr est. The ine vitability of CT in polytraum ati zed young pati ent s mu st be rememb ered, where the execution of a singl e examination, without add itional radiograph ic examination s, is less stress ful because th e pat ient does not have to change posit ion dur ing imag e acqu isition . It also allow s a compl ete assessment of both th e cran ial parenchymatous, visce ral thoraco- abdominal , and skele ta l components . ln fact , one of the advant ag es, part icul arl y with multislic e CT, is th e possib ilit y of retrospective rec onstruc tion of coll ected dat a (usuall y with 5-mm-thick layers) acco rd ing to different algo rithm s, using thinn er layers and a smalle r scan rang e.

1.8.4 Magnetic Resonance Imaging Like CT, this is a second-level exami na tion reserved for tho se ca ses that are not full y re solved with the pr imary methods. So far the use of MR[ has been lim ited by its co st, the fact it is not available in all dep artments, and its longer than average examination time . lt is inherently a multiplan ar and multiparametric examin ation, allowing direct acquis ition of informati on on di fferent space planes, and offering different ti ssue-t ype re prese ntations of th e same structure , high lighting th e evide nce of the ti ssue component in relation to the diagnostic probl em und er investigation . Tr-weightcd seque nces in part icul ar provid e gr eat anatomica l detail ; th ey highlight fat well and are particu larl y suitable for studies with intravenous injection of cont rast medium , wherea s Tz-weight ed sequences allow an accurate assessme nt of edema and flu id effusi on. In combination with algorithms for suppressi on from the fat signa l, and enhance me nt from the fluid , they are useful in assessi ng impac t bon e lesions, stress fractur es, and osteochondrit is dissecan s. Grad ient- echo sequences also allow an accur ate study of ligament s, tendons, meni scu s fibrocartilag e and art icular cartilag e, as th ey provid e precise evidence of hemo rrhage and labral lesion s. MR[ provides useful information and has valu abl e advant ages for demon strating some radiog raph icall y hidd en fractures, and in assessing impact bon e lesion s, balancing th e exte nt of di slo cation of ossification nucl ei (in ord er to addr ess a conse rvative or surgical therapeut ic approac h), in compl ex epiphyseal and apophyseal lesion s, and in subse que nt determination of a possibl e growth ar rest cause d by premature closure of the physis (partial or full), in stress fractures (tib ia, calc an eus, and cuboid), and in osteochondriti s dissecan s (knee , elbow hum eral condyle, talu s), as well as in demon strating meniscal , ligament , cartilag e and intra- and extra- articular tendon lesion s (Fig . 1.31). ln mon itor ing phy sis traum a, MR[ shows the extent and dire ction (tran sver se or longitudinal) of the le sion , and is also capable of recognizing the possible pre sence of a post-t raum atic transphy seal vascul arity th at pred ispo ses to the form ation of osteo-fibrous bridge prodromal growth disorde rs (g rowth arrest, angular defo rmities,

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Fig. 1.31 Sagitta l and corona l MR images of the left knee. The investigation documents the ACL lesion (a) , with evidence of artic ular effusion and hypointense focal area in T I (b) and hyperintense in T 2 sequences with fat signal suppression (c) at the lateral condyle, attributable to a bone lesion ca used by impact (asterisk)

shorteni ngs) if no t promptly tre ate d (r esect ion fo r bon e brid ge s invo lvi ng le ss th an

50% of th e physi s or e pi physio lysis for more ex te ns ive bone brid ge s) . In thi s regard, th e Shap ir o pathophy siological cl a ssif ic ation of fracture s inv olvi ng th e ph y sis, h a s become w id el y u sed, an d recog nizes th ree type s : • typ e A, in wh ich th e avascular ph y se al cart il ag e becomes a b arrier between the vascula r izati o n o f th e e pi physis and th at o f th e metaphy sis, prev enting the form ation o f trans physea l fi bro us o r bony b r idges type B, in wh ich the frac tur ed phy sis all ows a tr an sphy se al vascu lar commun ic at ion betwe en the epiphy sis an d met aphy sis (th is often occurs in Sal ter -H arris type I Y an d Y fr acture s) typ e C, in wh ich the fracture cause s an interruptio n of th e epi p hysea l vascu la rizat ion .

Suggested Readings Andrish JT (1990) Upper extre mity injuries in the skeletally immatu re athlete. In: Nic hols JA, Hershma rm E (eds) The upper extremity in sports medicine. CY Mosby, St. Louis, pp 673-688 Ecklund K, Jaramillo D (2002) Patterns of prema ture physeal arrest. MR imaging of I II patients. AJR Am J Roentgenol 178:967-972 Jaramillo D, Shapiro F (1998) Growth cartilage: normal appearance, variants and abnormalities. Magn Reson Imaging Clin N Am 6:455-47 1 Jaramillo D, Shapiro F (1998) Musculoskeletal trauma in children. Magn Reson Imaging Clin N Am 6:52 1-536 John son KJ, Bache E (2008) Imaging in pediatric skeletal trau ma. Springer Berlin Heidelberg Kuj ala U, Orava S (1993) Ischial apophysis injuries in athletes. Sports Med 16:290-294 Landin LA (1997) Epidemiology of children 's fractures . J Ped Orthop B 6:79-83 Light TR, Ogden DA, Ogden JA (1984) The anatomy of metaphyseal torus fractures. Clin Orthop 188:103-11

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Micheli LJ, Purcell L (200 7) The Adole scent Athlete. Spring er Scienc e, New York Ogden JA (2000) Skeletal injury in the child. Springer-Verlag, New York Ogd en JA, Gan ey TM , Ogden DA (1996) The biol ogical aspect s of children 's fractures. In: Rockwood CA, Wilkin s KE, Beaty JH (eds) Fractures in children , 4th edition. Lippi ncott-R aven Publisher s, Philadelphia, pp 19-52 Ozonoff MD (1991) Pediatric orthopaedic radi ology, 2nd edition. WB Saunders, Philadelphia Peter son HA, Madh ok R, Benson JT et al ( 1994) Physeal fractures : part I & 2 1979-1988. J Pediatr Orthop 14:423-438 Rang M (1983) Children 's fracture s. lB. Lipp incott Company, Philadel phi a Salter RB, Harri s WR (1963) Injuries involving the epiph yseal plate . J Bone Joint Surg 45 :587-622 Siffert RS ( 1997) The effect oftraum a to the epiphysis and gro wth plate. Skeletal Radiology 2:2130 Steve ns MA , EI-Khoury GY, Kathol MH et al (1999) Imag ing features of avulsion injurie s. Radio Graphics 19:655-672 Thornton A, Gyll A (1999) Childre n's fracture s. A radiologica l guide to safe practic e. WB Saunders Publishers, Londo n, UK Von Laer Lutz (200 I) Pediatric fracture s and dislocation , 4th editi on . Georg Thieme- Verlag, Germany Wilki ns KE (1996) The incidence of fractu res in children. In: Rockwo od CA, Wilkin s KE, Beaty JH (eds) Fractures in children, 4th edition . Lipp incott-Ra ven Publishers, Philad elphia Wootton JR , Cross MJ, Holt KW (1990) Avulsion of the ischial apophysis: the ca se for open reduction and internal fixation. J Bone Joint Surg Br 72:625 -627 Wulff RN, Schmidt TL (1998) Carpa l fracture s in children. J Pediatr Orth op 18(4):462-465

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2.1

Introduction

In recent years the incidence of traum atic mu sculoskeletal lesion s experienced by ind ividu als of pediatric age ha s been con stantly increasi ng; the majorit y of such traum a is linked to sporti ng activity. It is es timate d that in th e USA more than one-th ird of the total trauma in the 5-17 years age group is rela ted to sports, especially competitive sports . Although th ere is a lack of preci se epidemi ological data in Ital y, th e mo st recent studies sug ge st the inc idence is about the same. There are severa l reason s for thi s: inc rease d numbers of tho se participating in sports, and a greater avai lability of new spor ting activities a reduction in th e age at which ch ildr en firs t part icipate in competitive spo rts greater socia l pre ssure , espe cially the "mass medi a" portrayal of "winning sportsme n" pu shes young athl etes to go beyond th eir physiological limits in th eir de sire to emulate in competitive spo rts, and parents may also be pu shing their chi ldren to succeed . Regardless of the reas ons for th is increas e in incidence of ped iatric spor ts trau ma , it is important for the physici an to have a good knowl edg e of the num erous difference s that exi st between adults and children ; in the mu sculoske letal context it is particularl y important not to assum e that a ch ild is a small adult. In the subj ect of ped iatric age, it is important to understand the pathological pic ture in term s of the particular anatomy of the maturing skeleton (Fig. 2.1) especially the growth cart ilage (physis), the epiphyseal and apophyseal nuclei of ossification ,

C. Defilippi ( ~) Pediatric Radiology Service, Regina Margherita Children's Hospital, Turin, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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Fig. 2.1 Magnetic resonance image of the growth plate

and the tendons and jo int s. In young athle :es the se sites repre sent the centers of least resistance in the musculo skeletal app aratus, and are the sites of mo st frequent inj ury, wherea s in adult sportsmen when bony m. .turation is compl ete the struc tures that are least resis tant to mechanical inj ury are th» cap sular ligam ent s and tendon s. Thu s, similar mech anic al challenges c.m be the cau se of very different lesions, as for instance in the case of acute traum a 0 f the knee, which in an adult may result in lesion of the ligament s, while in a child tile same pathogenic mech anism will , in the majority of cases, instead cau ses a separa :ion-av ulsion of the tib ial apophysis. It should also be rememb ered that lesion s of the oth er structures ment ioned are also po ssible in children, although le ss common; the pathogenic mech ani sm described above is nearly always pre sent i ll chronic lesion s resulting from functional overlo ad or overu se. There are two separa te groups of traumatic lesion s rel ated to sporting activity: acute lesion s and tho se resulting from overu se. Acute lesion s are caused by situations of ten sion , load, or tor sion , and are characterized by immediate awareness of the damage and appearance of symptoms, with acute pain and function al immobility, and the damage is rea di ly apparent from rad iographic imag es. Thi s group includ es mai Illy fractures, as well as jo int disloc ation s and, in late adolescence, injuries to the j oints, tendons, and ligaments. In both the child and adolescent, " incomplete" fractu res are also found , at the level of the nucleus of ossific ation and the met aphy seal ca ·tilage, as well as apophyseal avulsion and osteochondral fractures.

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These types of lesion s, which are discu ssed in greater detail in oth er chapte rs, can usuall y be easi ly related back to the traumatic mechani sm, and, if co rrectl y treated, usuall y have an exce lle nt prognosis. Lesion s of overu se are instea d determ ined by microtr aumatic processes; the trauma may be endogenous, for example violent movement s that tend to excee d the physiolog ical limits of exc ursi on of a part icular joint, or forc e it to move in a plane that is not natural ; or it may be exogenous, cau sed for example by the ground the athlete is runni ng on, or by a particul ar piece of app aratus or sports equipment. Microtrauma repr esent s a mechani cal act ion that determ ines damage that is silent from the clinical point of view and is qu ickly repaired by the organism und er norma l cond itions; however, when the micro trauma is repea ted many times in a short space of time, as in cont inuous sporting pract ice, there is no time for structural recovery and the repeated sma ll lesion s summa te to result in anatomical alteration s that are ultimately present ed to the clinicia n. In the young athlete these types of lesions , which are less common in the adult, repr esent mor e than hal f of the tot al of spor ting trauma; th is is mainly becaus e during the growing phases, relatively sudden changes in body dim ension s caus e problems of motor coordination in the athletic man euv er, changing the type of stress and incre asing the likelihood of mic rot raum a. Thi s group , which forms the basis of discu ssion in thi s chapter, includes stress fractu res, osteochondrosis, osteochondriti s dissecans, variou s forms of osteochondritis and chron ic lesion s of the physis, and insertional tendonitis. It goe s without saying, particularly con sidering the age of the patient, that timely and correct identi fi cat ion of such lesion s is essent ial for suita ble treatment, in orde r to redu ce the long-term sequelae and allow rapid and optimal resumption of physical activi ty. In the diagno stic context of this traum a, diagno stic imaging has a role of fund amental importance, which, thank s to the tool s available tod ay, allow s early recognition from specific radiological images, which can be correlated to the pathological injuries and allow monitoring of the rep air processes over time .

2.1.1

Stress Fractures Stress fractures are defined as bone lesion s cau sed by re peated microtraumas that determ ine the physiological process of remodeling bony tissue, with the phenom enon of osteocl astic bon e resorption and a fai lure of cortical and cancellous bon e. The lower limb is most commonly involved in thi s type of lesion , particularly at the level of the diaph ysis of the tibia and fi bula, and especia lly in runn ers. These injuries are less common in the upper limb , where they occur particularly at the diaphy sis of the ulna and radiu s, primaril y in tenn is players, and of the olecr anon apophysis particul arly in gymn astics and throwing sports. They typic ally pre sent with swelling and pain that correlates to the physical activity, but without a preci se and reliable hi story for direct acute traum a.

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Fig. 2.2 A-P (a) and L-L (b) radiograph show a stress fracture of the right tibia. Note sclerosis and periosteal new bone deposition (red arrows ) through the upper tibia and the appearance of healing (white arrows) of the stress lesion

From the point of view of im aging, the se traum as are not easily identified by conventional radiogr aphy, particularly in the early stages when den se cortical th ickening is not yet apparent. (Fig. 2.2). In the initi al phase , the examination of cho ice is magn etic resonance imagi ng (MR/), whi ch is parti cul arly sensitive in detecting the physiological changes takin g place in the se fractu res, mainl y characteri zed by edema of the spongiosa, which is easily identifiable with the supressi on of fat sequences (Fig. 2.3) ; the ability to produc e a multiplan ar represe ntation ens ures optimal demonstration of the fractu re rim. However, th is doe s not result in a definitive diagno sis, and although ult rasonography is sens itive in the earl y phase it doe s not absolutely specify a diagno sis, whil e computed tomograph y (CT) is relatively specif ic but not suff iciently sens itive. The on set of low back pain in the adolescent athle te is not unu sual and in over 40 % of cases it is cau sed by the presen ce of a lumb ar spondy los is, with or without spondy lolisthesis . Therefore, when faced with such symptoms in a young athlete, th is will be the f irst hypothesis to be con f irmed or ruled out by diagnostic imaging. The spondy los is may be the result of a stress fractu re of the int erpeduncular line of the vertebral arch, and can have signif icant inc idence in particular sport ing specia lties, suc h as gy mnastics, swi mming butt erfly str oke, and diving. The conventi ona l radiological investigation should see k the "sign of the littl e dog" in obl ique proj ectio ns. CT or MRI can be used in case of doubt. A se parate cons ideration is a stress failure fracture, i.e. a fracture occurring in a

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Fig. 2.3 Tibial stress fracture. The early MRI shows the fracture line (a, black arrow) and bone marrow edema (b, white arrows)

bon e th at ha s become less resi stant to stress because of a deficit of bon e m in er al. Thi s is ob ser ved mo st commonly in femal es who tak e part in int en se sporting acti vites (p art icul arl y gymnastics an d long-distanc e run ning) , who show th e "female athl et e tr iad " sy ndr ome of re duce d pow er, ol igo-am enorrhoea, and osteoporo sis, often triggered by str ict d iet s couple d with in tense ph ysical act ivit y. This is a syn drom e with subtle on set , wh er e a stress fracture co uld repr esent th e first sy mptom, but it can be very dangerous for the health of th e young athl ete.

2.1.2

Osteochondrosis and Osteochondritis Dissecans Osteochondro si s and osteochondritis d issecan s def in e a nec rotic-deg ener ati ve typ e of pathology, relativel y common in adolesce nts, wh ich m ay affe ct epiphyseal growth of th e nu cl ei an d is gen erally se condary to re pe ate d compressive m ech an ic al ins ult. Th ese conditions are ch aracterized by mi cro vas cul ar lesions in th e ar ea subm itte d to mechan ical overload, re sulting in a locali zed deficien cy of blood supply leading to necrotic-degen erat ive ph enomen a, th e so-calle d osteochondro si s. In th e youn ges t subjects «11 -13 yea rs), in which th e nucleu s is sti ll in form at ion , the no rmal endochondral ossification is compromised, and th e nucl eu s becom es irr egul ar, frag il e,

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and liabl e to collapse. On the oth er hand, in mo st adult subjects (> 13-14 years), in whom the physis is settled and the epiphyse al nucl eus is fully develop ed, the avascular chall eng e can produ ce a circum scribed bony necro sis, which may develop fur ther to result in separation of a necrot ic fragment, so-called osteochondritis dissecans. Non-advance d cases of osteochondrosis and osteochondritis dissecans can be manag ed if the overload is rapidly reduced, avoiding the frag mentation and osteochondra l separation, and mo ve toward s reco ver y with res titutio in integ rum. Every nucle us of ossification can be the center of osteochondrosis, often with an early asy mptomatic cl inical cour se; however, there are some sites, linked to the repeated actions of a part icul ar athletic movement , where this has part icular clinical importance. In some cases, cor relation of the osteochondrosis with the overu se is int uit ive and now un iversall y acc ept ed, with repeated sporting microtraum as in which compression is dynamic; this is the case in Parmer disease, in which a lesion of the hum eral condyle is linked to the athletic throwing movement. In oth er cases (for instance Legg- Cal ve-Perth es disease of the proximal epiphysis of the femur, Scheuermann 's disease of the spine), the pathogeni c mechanism is att ributabl e to the physiological gravitational load, some times with endocr ine -metabolic influ enc es, to which compre ssion and overuse overlo ad, linked to the sporting practice are sometimes added. The pro cess of osteo chondritis dissecans begins with dissection of an osteochondr al fragment, typi cally at a convex artic ular surfa ce, with sub sequent appearance of subchondra l necro sis followed by formation of an osteo chondral sequestra tion formed by the nec rotic bone and overly ing cartil age . Conventional radiological investigation sometimes reveals the det ached fragment in mo re adva nced cas es ( Fig. 2.4) , but it is better documented by CT. Once agai n, the most acc ura te method is MRI , which cle arly underl ine s the lesion as a defect on the cortical surface, which appears as an area of depre ssion ; subsequently, the osteo chod ral fragment can be observed as an area of intermediate intensity on both T,- and Tz-weighted sequences.

Fig.2.4 Osteochondritis dissecans ofthe knee. X-ray appearance of the typical bony defect of the medial femoral condyle (arrows)

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Fig.2.5 Osteochondritis dissecans of the knee. The MRI shows a small condylar bony defect

In the intermediate stages, where the separation is sti ll adjacent to the cortex, a narrow zone of low intensi ty on T2 is see n, which reveals separation of th e lesion from health y bon e; conversely, when th ere is tot al separa tion of the necrotic fragment , a bord er of high-d en sity separati on is ob served in T2, which shows the presence of joint flu id (Fig. 2.5). It may be nec essary to perform an MRI evaluation of the joint for a mor e prec ise evaluation of the stability of the fragment, but onl y in cases where th e arthrographic effect, induc ed by th e intra-articular fluid .

2.1.3

Osteochondritis The term osteo chondriti s indicates a group of di sorders of growth of the apophysea l nuclei of ossific ation that are infl amm ato ry-degenerative in nature and secondar y to repe ated avulsion-type mechanic al insult . They are characterized by insertional chondral and tendon microlesion s, followed by inflamm ato ry and rep arative proce sses. The chondral microle sion s and infl amm atory hyperemia result in acc elerate d endochondral ossification of the apophysis , which is disorg an ized and multicentric. Therefore, the growth nuclei of the apophys is are lar ger, irregular, and multiple . However, the mo st characteristic pathological ch ange is inflammation of the ar ticular cart ilage , whi ch appears thickened and hype rem ic . The di sorder has a slow course, which is benign, in which the infl amm ator ydegenerative proce ss spontaneous ly regresses, with subse quent rep air and definitive ossifi cat ion of the nucle us; however, the re are residual hypertroph ic morphological alt erat ion s of the apophyseal nucl ei involved. Th e pelvi s and knee are th e sites with the great est numb er of apophyse al growth nucl ei, and are therefore also th e sites most frequently affe cte d by apophyseal

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detachment in situa tions of viol ent insults an d acute avuls ion, or of apophy seal osteochondriti s wh ere th er e is re pe ate d chr onic traction . From th e point of vie w of imagi ng, th ese pathologi es have a ve ry typ ical pres entat ion , wh ich is eas ily identified by th e different m ethods. On convent ion al radiograph y, scl ero sis and defo rmity in th e nu cleu s of ossification, whi ch often results in fragm entat ion an d diasta sis from th e adjacent bon y stru ctures (Fig 2.6), are ob ser ved . Th es e find ing s are also vi sibl e on ultrasound exami na ti on, wh ich also shows swe ll ing of th e apophyseal car tilage, signs of tendon dam ag e (th ick en ed and hypo echoic) , and th e po ssib ility of as sociate d bursitis (Fig. 2.7).

Fig 2.6 Osgood-Schlatter disease. X-ray appearance of the sclerosis, diastasis, and fragmentation of the tibial tubercle

Fig.2.7 Ultrasonographic pattern of Osgood-Schlatter disease. a Irregular appearance of the tibial tubercle; b color-Doppler scan shows a chondro-tendinous insertion with hyperemia of the infrapatellar tendon; c deep infrapatellar bursitis

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Fig.2.8 Osgood- Schlatter disease. Magnetic resonanceappearance of thetibial irregularity and the tendon involvement

Th ese find ing are bett er vis ualized on MRI ( Fig. 2. 8), but thi s should be reserved for rar e cases of sonographic-negative fir st-level exam inations in the presence of a suggestive clinica l hi story, and for osteochondritis.

2.1.4

Chronic Lesions of the Physis Chronic lesion s of the physis repr esent th e result of repea ted mechanical overload, again st the cartilage growth plat e, which can be impose d by vectors of stre ngth avulsion - tangent ial or tor sion al. Chronic anatomical damage, equivalent to a type I Salt er-Harris lesion (fo r example, little leagu e shoulder), or a mechani cal insult may be expresse d as vectors of forc e in compressi on, causing chronic cru shing injury of Salt er-Harris type V (e.g. crus hing and prevent ion of growth of the distal physis of th e radi us in gymn asts) . In th e next sections, we will revie w some of the mo st common bon e and joint diseases resulting from overuse, involvi ng th e app endicular skele ton, which are oft en correlated to specific sporting specialties.

2.2 The Upper limb 2.2.1

Little League Shoulder Thi s term refers to a type of lesion that mainl y affe cts athl etes who enga ge in throwing sports, particularly tho se involv ing "ove r the head " actions, or a mov ement where

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the limb is plac ed in an ant erior elevation of 90° and maximum exte rna l rotation . Sports parti cipant s falling into thi s category are prim arily pitch ers in baseball and light athl etic s, and secondarily volley ball and tenn is players and swimme rs. This pathology repr esent s a good example of how repeated stress at an osteoarticular structure can give rise to different clinical pictu res, according to the degr ee of maturation of the musculoskeletal app aratu s. In adults, the chronic microtrauma from tract ion leads to inj ury of the ca psular ligam ent , while in the adol escent it act s at the level of car ti lage growth of the proximal hum eru s, where it result s in a pathological chang e comparabl e to a Salt er-H ar ris type I lesion. The onset is typicall y between II and 14 years of age, with gradu al emerge nce of pa in at the lateral proximal hum eru s during athletic movement , which increases to prevent prop er use. It is therefo re a chronic avulsion-ty pe lesion of the physis, charac terized by a broadening of plate car tilage growth , which is easi ly recogni zed on radiograph s of the hum eru s, part icularly if perform ed with a bilat eral comparison, and especia lly evide nt on the lateral margin . The avul sion microtraum a respon sible for the carti lage injur y is typicall y accompan ied by an infl amm ato ry component , which mak es for a hyperint ense signal that loc ates the phy sical suffer ing as a result of damage in the early stag es, while Tzweighted MRI sequences also show fat suppressi on.

2.2.2

Osteochondrosis of the Humeral Condyle (Panner Disease) Pann er disease is an osteochondrosis of the hum eral cond yle that characteristicall y occurs in children who play baseball and oth er throwing discip lines, and less often in young gymna sts, and is due to repeated micro traum a from lateral compression of the hum eru s-radius articulation , cau sing alteration s in the cartilag e growth nucleus of the hum eral cond yle. It is clinicall y charac terized by latera l elbow pa in, with progressive funct ion al impotenc e, that begins befo re the age of 10 years; the early onset suggests a differential diagnosis in comp arison to osteochondritis dissecan s, als o confi rme d by diagno stic imaging, but which, by definition , only occur s after clo sur e of the physis, after the age of 13-14 years .

2.2.3

Osteochondritis Dissecans of the Humeral Condyle The distal hum eru s, and particularl y the hum eral cond yle, is one of the places where this pathology is frequently see n. The young athletes mo st affected are tho se practi cing activities that involve a valgu s stress of the elbow, subj ecting it to repeated lateral compression traum a, with particular side-impact on the hume ral condyle. Prompt

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diagnosis and sub sequ ent removal of the load will ena ble rec ove ry ; oth erw ise, the disord er will prog ress to dissection and se paration of th e osteochondral joint. Early diagnosis may require ultra sonography or MRI.

2.2.4 Little league Elbow Syndrome Thi s sy ndrome, whi ch is excl us ively observed in pitch ers (baseball and oth er throwing spe cialties ), is characte rize d by the involveme nt of different struc tures that form th e ar ticulation of th e elbow, and therefo re repr esent s a valid mod el for th e study of overload lesions in pediatri c age, due to mic rot raumas from both compressi on and traction. Th e complex biom echanics of th e athletic gesture mu st be tak en into acc ount. Th ese include a tor sional tw ist with a rapid rotation of th e shoulde r and elbow extension; this is followed by a violent stress in valgus extensi on at thi s joint , wh ich produc es injury from compression aga inst the lateral compartme nt and traction at th e medial and lat eral level. In adults this picture is usually transl ated into pathologies of the lig aments and tendons, in disorders such as late ral uln ar ligament lesions, due to valgus stress ; insertional enthesop athy of the olec ranon ; and medial epicondylitis. In contrast, in young athl etes, the tract ion is ins tea d load ed onto the corresponding ca rtilage growth plate, resulting in apophyse al endoc hondrosis of the corresponding medial epicondy le of the olec ranon. In additi on, the presenc e of osteochondrosis ca use d by compressi on of the hum eral condyle (Pann er di sease in the younges t athl etes and osteochondritis di ssecan s in late adoles ce nce ) is associat ed with a simi lar pro cess at the radi al head. Th e onset of symptoms is typ icall y bet ween 9 and 14 years, at fi rst with a reduction in the spee d and precision of throwing , and subse quently with th e app ear anc e of diffu se pa in in the whol e joint , wh ich is mor e inte nse in the medial epic ondy le .

2.2.5 Osteochondritis of the Olecranon Apophysis Unlike th e for me r case, this lesion is ob served part icul arl y in spor ting act iviti es where there is a re peated and viol ent contraction of th e tricep s mu scl e again st a resistan ce; typical exa mples are power laun ch ing , such as in weight tra ining and gymn astics. Th e mic rotrauma ac ts on the olec ranon inser tion of the tri ceps, provo king the typical osteochondritis of apophyseal traction , characterized clinicall y by pain and fun ctional limitation.

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2.3 The Lower Limb 2.3.1 Osteochondrosis of the Epiphyseal Nucleus of the Femur (legg-Calve-Perthes Disease) This rare disord er is found as a pathog enic osteochondrit ic cofacto r in mechan ical insult from overu se. [t particularly affects childr en aged between 5 and 8 years, although they may not be performing any strenuous overactiv ity. The disorde r is usually bilater al but may be unilater al. There is a possible link with overu se, but pathogene sis is very margin al.

2.3.2 Epiphysiolysis of the Epiphyseal Nucleus of the Femoral Head Thi s type of lesion may be the result of chronic overlo ading with combined shear and compressi on forces acting on the growth plate cartilage, lead ing to a complete or incomplete Salte r- Har ris type [ lesion. ln the case of a complete lesion of the physis, separation of the epiphysis and its slippage is verifie d. [f it is the result of a rela tive overlo ad (or insufficiency), a normal load can becom e excessi ve for a growth plate that has been weakened by previou s unfavorable hormonal influences (oft en hypogon adism) .

2.3.3 Osteochondritis Dissecans of the Femoral Condyle (Konig Syndrome) The convex articular surface of the femor al condyle (part icul arly the medi al part) represents the most frequent center of osteo chond rit is dissecans, and is apparently related to repe ated comp ression microtraum a in sport ing activites such as footb all , involving energetic stress in the knee jo int.

2.3.4

Osteochondritis of the Inferior Pole of the Patella (Sinding-larsen-Johansson Syndrome) Th is corre sponds to Osgood -Schlatter dise ase at the inferior growth plate of the pole of the patell a. lt is not frequent as an isolated lesion, but is often found in conj unction with patellar tendinits (jumper's knee).

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2.3.5

Osteochondritis of the Anterior Tibial Apophysis (Osgood-Schlatter Disease) Osgood-Schlatter disease perhaps represents the best known and studied form of osteochondr itis of the whole skeletal apparatus. It is found in young athletes who undertak e running and jumping sports, and is caused by repeated traction microtraumas that act at the anterior tibial apophysis and the site of insert ion of the patellar tendon. It man ifests bilat erall y in 20-30% of the cases in children aged between 10 and 15 years, with knee pain exacerbated by activi ty linked to swelling of the apophysis . From a diagnostic imaging point of view, the most usual examination is ultrasonography, which, in addition to rad iographic identif ication of ir regular fragmentation of the ossificat ion nucl eus of the apophysis , also gives evidence of the alteration s that are typi cal of th is pathology, such as patellar tendon itis, deep infrapatellar bur sitis, and, above all , swelling of the apophyse al cartilag e.

2.3.6

Shin Splints This is defined as damage to the periosteum of the anterior (or, more rarely, poster ior) tibi al cortex, due to cont inuous stress tract ion occurring as a result of running, at the posterior of the exte nsor digitorum longus (or, if posterior, the flexor digitorum longus and soleus) in children, where, because the perio steal acti vity is high er, thi s cl inical picture is mo st oft en found . The clini cal symptoms are typi call y pain with redness and swelling at the lesion . The pathological picture is characterized by disconnected perio steum (periosteal stri pping), which is recurrent and of low grade, but over time stimulates perio steal osteogenic activi ty and determ ines the app earance of a focal periostitis on the rad iographic or CT ima ge . MRI performed in the acut e pha se and sequences using high con trast can highl ight a characteristic hyperintense band.

2.3.7

Osteochondritis Dissecans of the Talus The talar dome is a relatively frequent center of pathology ca used by compr ession microtraumas, especia lly in running and j umping sports (landing phase). The evolution of the patholog y and diagno stic imaging is as usual for dissecting osteochond ritis.

2.3.8

Osteochondritis of the Calcaneal Apophysis (Sever Disease) Thi s is similar to the previou sly describ ed apoph yseal chondritis, and has been recognized since the early years of the last century to be a result of tract ion overlo ad on

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th e calc an eal apophysi s from th e Achill es ' tendon in yo un g runners. Th e clinic al and imagi n g pictures are si mi lar to those described ab ove, although th e ra d iog raphi c p icture can be confus ed by th e ph y siological d en sity of the nucl eus of o ssifi cation, whi ch is often ob ser ved . In cases of doubtful inte r p retati on it is th erefore useful to u se MRI.

2.3 .9

Osteochondritis of the Apophysis of the Base of the Fifth Metatarsal (Iselin Disease) This is caused by traction inj ury of th e ba se of th e f ifth m etatarsal , by th e tendon o f th e sho rt per in eal muscl e, and is es pec ia lly found in yo un g j um pers .

2.3.10

Osteochondrosis of the Head of the Second Metatarsal (Freiberg or Koehler II Disease) This is o steochondrosi s th at is prefe rent iall y lo cated at the ep iphyse al nucleus of the h ead of th e second m et atarsal , but can be found, le ss fre q ue n tly, at th e th ird m et ata rsal. The disea se prog ression an d im agi ng are th e same as usu al for o st eochondro si s. It is enc o unte re d most frequently in you ng runn er s .

Suggested Readings Abraham E (1992) Sports-related injurie s in children and young adults. Compr Ther 18(12) :33-7 Aoki Y, Yasuda K, Tohyama H et al (2004) Magnetic Resonance imaging in stress fractures and shin splints. Clin Orthop Relat Res (421):260-267 Bernhardt DT, Landry GL (1995) Sports injuries in young athletes. Adv Pediatr 42:465- 500 Cain EL Jr, Dugas JR, Wolf RS, Andrews JR (2003) Elbow inj uries in throwing athletes: a curre nt concepts review. Am J Sports Med 31(4):621-635 Cassas KJ, Cassettari-Wayhs A (2006) Childhood and adolescent sports-related overuse injuries. Am Fam Physician 73(6):1014-22 Hatem SF, Recht MP, Profitt B (2006) MRI of Little Leaguer 's shoulder. Skeletal Radiol 35: 103106 Maffulli N, Bruns W (2000) Injuries in young athletes. Eur J Pediatr 159(1-2) :59-63 Pommering TL, Kluchurosky L (2007) Overu se injuries in adolescents. Adolesc Med State Art Rev 18( I):95-120 Raissaki M, Apostolaki E, Karantanas AH (2007) Imaging of sports injuries in children and adolescents. Eur J Radiol 62( I):86-96 Wilder RP, Sethi S (2004) Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints. Clin Sports Med 23( I):55-8 1

Osteoarticular Trauma in the Pediatric Age: Overview - Apophyseal Injuries

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M. Valle, A. TaJ,:lial1co. L. Oppezzl, N. Gandolfo, P.Toma a nd C. i\lartinoli

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Introduction

From the anatomical point of view, apophyses are protuberances on bone (from Gr eek u1toqn<JlS, composed of apo "to bring forth " and physis "to grow") that make up specialized struc tures for the atta chment of tendons and ligaments. Among chi ldren and adolescents, lesion s on the apophysis are a common clinical probl em re lated to spor ting and recreat ion al activities . This is due to the fact that, between the age of 12 and 16 years, the structure of apophyses makes th em vuln erabl e: th e development of the ir ossific ation center is not yet complete, and the cartilage , under hormon al infl uence, loses elas ticity and is unabl e to give f irm sta bi lity to the osteo tendinous junction. Hence, rough application of shear or tor sion force s, exer ci sed upon th e apophyse s by tendons and lig am ent s, can overcome th e thr eshold of cartilage and bone resistance . Thi s may res ult in fragmentation or detachment, wh ich consequently impairs fun ction to an extent that can be mo re or less disabling for the pat ien t. The range of apophysea l injuries is extremely bro ad and is influenced by the following factors: degr ee of bon e and cartilag e maturation (and, therefore, age of the ch ild or adolescent at the time of trauma) ; anatomical loc ation of the apophysis; and the geometry and deg ree of th e forces appli ed to the myot endinous sys tem. Th is pathophysiologic complex ity may expl ain the large number of terms used to de fine thi s typ e of inj ury, oft en generating confus ion in descriptions of th e proc ess itself. Term s range from "apophyseal irritation ", to "traction apophys itis", "osteochondrosis", "c hron ic apophysitis" , "osteochondritis", and "apophysea l se paration" . Dur ing skeletal maturation , apophys eal injuries are cau sed by a traction mechan ism that produces traum at ic inj ury to the ca rtilage and bon e. Th en , there is a sequence of

C. Martinoli ([2;1) Radiology Department - DISC, University of Genoa, Genoa, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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overlapping damage-repair events . Unde r these circum stanc es, the diagno sis influence s the decision with respect to the treatment strategy and the resumption of sporting activity. In the diagno stic work-up, imaging plays an important role in confirming the clinical findings. In this chapter, we will first conside r apophysea l injur ies caused by tendon tract ion, then look at tho se deri ved from lig ament tract ion .

3.2 Tendons Substantial differences exist betw een the pathology of tendon s occurring in the pediatric age comp ared to that of the adult. Thi s is because in a child or an adolesc ent, a degenerative proce ss of the tendon substance is never pre sent , except in exceptional cases and in relation to systemic disord ers or to severe osteo-articular abnormalities . Tendons in the child are fibrillar structures , whos e image in radiolog y differs from that of an adult only by their sma ller size and the ir insertion, which at thi s age consists parti ally, if not tot ally, of cartil age on the apophysis.

3.2.1

Pathophysiology At the site of insertion into apoph yses, tvo main categor ies of tendon lesions may occur: chronic and acute. The first, which is more frequent, is caused by microtrauma from repeated tract ion , often in rel ation to a funct ional overlo ad (overu se) during sporting activities. These injur ies lead to abnormalit ies of the tendon-to-bone interface , with fragmentation of the apophysesI cartil age and fibroca rtilage and/or of the underlying imm atu re bone . The degree of avulsion of the apophy seal structures induced by traction trauma is minim al a id does not signif icantly compromise the biom echanics of the structure s attaching on it. When detachment involve s fragm ents of cartilage of an imm ature apophysis, the se can later become ossified, forming small foci of heterotrophic ossification in the so ft-tissues - in general the se are easily identifi ed by imaging modalities. These foci are separated from the apophysis and localized in cont inu ity with the tendon fiber:.. The distance intervening between these ossicles and the apophysis is short, and almost invar iably filled with fibroc artil age or with a fibrous bridg e. If the degr ee of displac ement of the oss icles is not much and they are in clo se contact with the apophyseal cartil age, they can be totally rea bsorbed inside the apophysis during the matur ati on proce ss of bone, as growth eventually encompasse s them . In these cases , a sub tle prominence (callu s) or deformity may develop with apophysea l enlargement : dit ferent ial diagnostic probl ems with aggressive lesions are unu sual in these cases. 011 the oth er hand, when the fragment is dislocated far away from the growing apophysis, it can be transform ed into a permanent ossicle, tot ally separated from the main bone, and may ass ume a spherica l or oval shape with a thin cortical cover. The typi cal location of the ossicle along the cou rse

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of a tendon or a ligament and near its insertion allows its identifi cation as differ ent from sesamoid bones. The faet that these lesion s are the con sequ ence of repeated injur ies over time - even if minimal - lead s to an intermittent eour se of symptoms, with alterna ting phases of exacerb ation and rem ission of pain . In contrast to chronic lesions, acute apophyseal inj uries derive from a unique indi rect major trauma. In these inj uries, the tendon applies an excess ive tract ion forc e with respect to the resis tance posed by an apoph ysis that has not yet reach ed full matur ation and biomechanic al con sol idation . The result is parti al or complete detachment of the apophysis on which the tendon is inserted or, more rarely, avulsi on of the tendon from its bony insertion. Acute apoph yseal injuries can be subdivided into major and minor types based on the degr ee of dislocation of the apoph yseal fragment. Majo r apophysea l lesion s cause dislocation of the apophysea l fragment, which is avulsed to such a gre at extent that it cannot any longer be reabsorbed. Growth may become comp rom ised or cease, and, in the case of complete avulsion, a significant biom echan ical deficit occur s. In general, and especially at the ischia l tuberosity, an injur y is con sidered major when the distan ce between the bone fragment and the nidu s of avulsion is gre ater than 2 em, or when the avulsed fragment is exceedingly large : in the se cases, the treatment is surgical and is based on reatta chment and anchoring of the apophysis onto the bone by means of a screw. When the applied force is not enough to cau se complete avul sion of the apophysis , the pattern of fragment ation can differ, involving variable amounts of car tilage and bone . This proce ss is modul ated by the method of applica tion of the force, the conformation of the apoph ysis, its degr ee of matur ation , and the physical activity. Generall y speaking, the se minor injuries can be easily distinguished from the mo st common chronic one s, based on their location and morphologic appeara nce, since detachment doe s not cau se loss of relat ion between the avulsed fragm ent and the nidu s of avulsion. In both major injuries and the minor form s, the detachm ent is related to the damage of one of the histological component s of the apoph ysis that are arranged "in series" to resist traction . The se structures are: the growth car tilage of the apophysis the secondary ossifi cation center (if present) a layer of fi brocar tilage or, less commonly, of perio steum on which the tendon fibers directly inser t. In most cases, the lesion occur s at the level of the apophyseal cartil age located above the secondar y ossific ation center. From the clinical point of view, chronic and acute apophysea l lesion s differ from each other in many respect s. Conce rni ng chron ic lesion s, the f irst occur renc e of symptoms is only vaguely remembered by the young athlete; symptoms are typically milde r and inte rmittent ; sporting or othe r phys ical activities are not hindered by pain ; and patients can be treated con servatively with rest, support, and symptomatic therapy. On the other hand, in patient s with acute lesion s, the functional disability and pain are typically related to a recent trauma that is easily remembered by the patient (who can describ e in detail the mechanism underlying it). There is a sudden onset of pain, immediately causing the subject experience a disablin g condition with difficulties in standing or walk ing . The sporting activity can eventu ally be resumed, upon the

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recovery of strength in the mu scl e group invol ved, and when movements can be execute d without rest rict ion and pain. The treatm ent , which depend s upon th e size of the avulsed fragment and the degr ee of dislocation , can , in extreme cases, include surgery. Th e prec ise tim ing to corr ectl y carry out this approach is still being debated, but in all cases the prognosis is exce lle nt.

3.2.2

Imaging In chronic apophyseal lesion s, plain film s are gen erall y suff icient to mak e the diagno sis by showing fragm ent ation of th e apophysis. Ultr asound can be used in the phases of re-ex acerbation of symptoms to check the status of the tendon insertion . Although magn etic reson anc e (MR) imaging can show marrow edema at th e level of apophyses, its use is not justified in typ ical cases. Th is is becau se the decision to res ume sporting activities by the child or th e adoles ce nt is esse ntially based on clinica l criteri a, and not on imaging findings. Instead, MR imaging can be helpful in ca ses with atypical present ation , when th ere is any doubt about wheth er oth er pathology may be present. An example of th is could be a patient with anterior knee pain, when patellar in st ability, bone mi salignments, or other os seous pathology (osteomyelitis) is suspected in the differential diagnosis list for an Osgood-Schlatter or a Sind ing-Larsen-Johansson disease. In acute apophyseal lesion s, the patt ern of avuls ion may be variabl e at imaging bas ed on the structure involved, especially in the pha ses immediately after the trauma, when the amount of detached bon e and/or cartilag e can vary greatl y. In general , the radiog raphic examination can demonstrate the apophysea l detachment, although inj uries with minimal dislocation and parti al apophyse al involvement may be hard to recognize. Side compar ison can be useful in case of mild apophyseal dislocation. In chronic avul sion s that have alr eady been stabilized, pla in film s can occ asionally depict a hypertrophied callus at the level of the apophysis (apophyseal hyperostosis), possibly mim icking an aggress ive lesion . In th ese ca ses, know ledg e of the exact anatomic sites of ten don insertion into bone may help to prevent misdi agnoses. In the acute sett ing , if radiography does not provide conclusive information (this especially happens in the event of minor dislocations), ultrasound and MR imag ing can playa dec isive role in confirm ing the apop hyseal inj ury. Ultrasound has the advantage of being a clinical examination, directed towa rds the pat ient 's symptoms and, with highreso lution small-parts transducers, it is able to identify even minimal abnorma litie s of cartilage and bone. MR imaging can recogni ze the pre sence of effus ion and edematou s chang es around th e apophyseal growth cart ilag e. Hemorrhage often extends alongs ide the tendons involved, in a location far from the bone insertion. In minor apophyse al injuries, ultr asound used as a part of a compl ement of radiographic examinations can be enough to diagnose and characterize the inj ury. However, for cost rel ated reasons, the use of MR imaging should be rese rved for the evalu ation of major apophysea l lesions and to make a preo perative evalu ation .

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3.2.3 Chronic Apophyseal Lesions Due to Tendon Traction In the pedi atric age group, the main exa mples of apophyseal lesion s that deriv e from chronic m icrotrauma occur at th e level of the kne e - with the so-calle d Osgood-Schlatt er and Sind ing-Larsen-Johan sson diseases ; and at the level of the ankl e - with Seve r's dis ease and acce ssory navicular syndrome . Osgood-Schlatt er di sease re fe rs to an apophysit is (although the term is used some what inappropriately) of th e tibial tub erosit y, which is oft en obs erv ed in infants and adoles ce nts, reac hing its peak betw een th e ages of 10 and 15 years . Th is condition occurs mo st frequentl y in boys who pract ice sporting activities that involve jumping (e.g. basketball , voll eyball) and apply repeated stress forc es on the extens or mech anism of the knee. Osgood-Schlatt er disease is typically secondary to repeated traction exe rted by th e pat ellar tendon on th e sec ondary nucl eu s of ossifi cation of the tibial tube ros ity. Th e lesion occurs when the chondral cell s of the apophysis are hypert roph ied, in th e so-ca lle d " pre-ossi f ication" phase. Once the trauma ha s occurred, the cartilage and bon e fragm ent s proceed with th e proc ess of oss ification and increase in volume until th ey becom e visible on pla in film s in the pretibi al area . The spa ce between the se fragments and the avulsion site is filled with fibrous ti ssue or fibroc artilage . In the late phases, ossification of the intervening space can occur if the ga p between the fragments and the tibi al tubero sity is of limited extension . On the other hand , if the di sloc at ion is greater in extent, the avulsion fragments tend to ossify inside the tendon, forming ossicles, which become perm anent after growth has completed. Clinica lly, Osgood-Schlatte r disease presents with a lump located superfici ally to the tibi al tube ro sity . The lump may be tot ally asy mptomatic or may be ass ociated with recurrent pain that is typ ically exacerbated by phy sic al activity. Plain film s demonstrate a fragmented tibi al tubero sity ; in early disease, however, the bone surface may appear normal. It should be taken into account th at the ossification center of the tuberosit y can be multicentric : thi s may cause problems in the different ial diagno sis between normal and pathological cases. Fragments are typ ically found in front of or crani al to the ossific ation center, and have a thin sclerotic rim which allows th is condition to be di stinguished from acute avulsiv e inj ures (Fig. 3.1a). Ultras onography ( US) can identify early abnor ma lities in the soft and chondral tissues, onto wh ich the patellar tendon inserts. The mo st typical signs are soft-tiss ue swe lling, tenderness, and fragmentation of the secondary ossific ation center, thi cken ing of the tendon ins er tion with ass ociated echotextural abnorma lities , and infra patellar edema (Fig . 3.2a, b). The se signs , however, do not correlate with clinical sy mptoms, disease severity, and patient outcome. In acute pha ses with intens e pain and functiona l disability, a distended deep or superf icial infrapa tellar bursa and int ra- and per i-tendinous hyperemia at color- and power-Doppler imag ing can be found . Compared with US, MR ima gi ng seems to be more sens itive for demonstrating early signs of d isease, allo wing identification of marrow edema at the level of the tibial tub ero sit y (Ti -hypo int ensit y and T2-hyp erinten sit y) in the ea rly phases oftrauma , when rad iography is sti ll nega tive ( Fig. 3.2c). Osgood-Schl att er disea se see ms to accel erate physeal ossification but is not assoc iat ed with an incre ase d ris k of

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Fig.3.1 Chronic traction injuries. a Standard lateral radiogram ofthe knee in a pati ent w it h O sgoodSchlatter disease reveal s bone fragments (arrow) at the level of the distal patellar tendon . b Bone fragmentation at the proximal (wh ite arrow ) and distal (open arrow) insertions of the patellar tendon reflecting Osgood- Schlatter and Sinding- Larsen- Johansson diseases

Fig. 3.2 Osgood-Schlatter disease. a Sagittal US image (17-5 MHz) of the normal tibial tuberosity shows the patellar tendo n (1) inserting into the tibial tubero sity (3). A thin layer of hypoechoic cartilage (2) that represents the residual of the growth cartilage of the tubero sity is observed . Note the bone notch (4) that separates the tuberosity from the tibial metaphysis (5) and the patellar tendon (arrowheads) that overlies the tuberosity to insert, with its most caudal fibers, on the latter. b Corresponding US image in a patient with Osgood-Schlatter disease. The tibial tuberosity has an irregular bony surface with detachment of some bone fragments (arrows). At the same time, the cartilage is not adherent to the underlying bone owing to the traction exerted by the patellar tendon. c Sagittal fat-suppre ssed turbo spin-echo (tSE) T2-weighted MR image of the knee in the same patient shows bone marrow edema (asterisk) at the level ofthe tuberosity and the most anterior part of the tibial epiphysis. Deep infrapatellar bursitis is also seen (arrowhead)

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fracture-avuls ion of the tub erosity. Treatm ent is cons er vative and requi res rest, nonsteroidal anti- inflammato ry drug s (NSAlDs), time and - for complete resolution full bone maturity. Sinding-L arsen-Johansson disease affects the origin of the patellar tendon from the infer ior pole of the patella. Thi s disord er is similar to but far less common than Osgood -Schlatt er disease. [t occurs in childre n who are slightl y older (10-12 years) than thos e affected by Osgood -Schlatt er disease and is oft en associated with this latter cond it ion, given that the ris k factors and the pathological mechanism are the same. Radiographic examinat ion shows fragmentation of the distal pole of the patella, a patt ern that may mimic a type I bipa rtite patella (Fig. 3. Ib). At some stages of maturation and in predisposed subjects, the traction exerted by the patellar tendon on the inferi or pole of the patella (wh ich is entirely chondral) can lead to an increa sed prom inence of bone instead of fragmentation patt ern s. In these patients , the protuberant bone can create a conflic t with the deep fib ers of the patellar tendon , especi ally during knee flexion , caus ing patellar tend inosis (jump ers' knee), a condition that can becom e symptomatic in adoles cents or in adulthood . In jumper 's knee, tendinop athy has a mor e chronic evolution compared with Osgood - Schlatter or Sinding-Larsen-Johansson disord ers. US is able to distinguish the apoph yseal involvement from prim ary tendon abnorma lities. Another typical site for chronic apophyseal injurie s is the posterio r heel apophysis . Thi s cond ition , which is also referred to as Sever s disease, occurs in pre-adole scent athletes who take part in sports activities such as racing and jumping (footb all, basketball , etc) . Similar to the other disorders described previously, calcane al apophysitis is related to chronic microtraum as and fragmentation of the secondary ossification center of the heel at the insertion of the Achilles tendon . Often bilater al, Sever 's disease causes local soft-tiss ue swelling and heel pain that is worsened by activity and movement. In pathogenetic terms, it must be remembered that the age of appeara nce and fusion of the poster ior ossification center of the calcaneus is variable and doe s not allow a clear identi fic ation of pathology based on the patterns of apophyseal developmen t. lt has been shown that Sever's disease occurs when the ossificat ion nucleus has already appeared but has not yet fused . Although calc aneal apophysitis has been related, in the past, with the sclerotic appeara nce of the ossific ation cente r, this sign doe s not seem to be pathologic in itself, as it may be encountered in normal children. On the other hand, a mult ifragmented nucleus at an extent gre ater than the contralateral side can be regarded as a diagno stic sign that correlate s well with clinic al symptom s. Sim ilar to Osgood-Schlatte r disease, US can show degenerative change s in the ret rocalcane al portion of the Achilles tendon . Intra- and peri-tendinous hyperemia can also be identified. Around the med ial aspect of the midfoot, apophysea l inju ries may occur at the insert ion of the posterior tibi al tendon into the tubercle of the navicul ar. Thi s lesion occurs when the secondary ossifi cation cente r of the tube rcle has not yet fused with the main body of the navicu lar and is j oined to this latter through a f ibrocart ilaginou s or fibrous bridg e, which is oriented transversely to the tendon axis. The result is formation of an ossicle, which is present in almost 10-15% of the normal popul ation in the first decade of life. This ossicle is commonly known as type 2 access ory navicular.

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Part of the superficial fibers of the posterior tibial tendon insert on the accessory ossicle , instead of the navicular. Espec ially in children who practice sporting activ ities or have flatfeet, the repeated tractions exerted by the posterior tibial tendon on the synchondrosis and some lack of stability of the ossicle can lead to a painful syndrome, the so-called accessory navi cular syndrome. With time and repeated mierotrauma, degenerative osteoarthritic changes can develop at the level of the synchondrosis, with areas of subchondral sclerosis, pseudoeystie changes, and an irregular surface of the ossicle. Plain films can display these bone changes. MR imaging is able to recognize signs of bone marrow edema in the subchondral bone , thus confirming the presence of a chronic traction injury. US can correlate the painful area with the locat ion of the synchondrosis and can exclude pathology affecting the distal posterior tibial tendon (which looks normal in accessory navicular syndrome) and the spring ligament. When symptoms become relevant, the ossicle can be removed surgically and the posterior tibial tendon can be reinserted directly into the navicular.

3.2.4

Acute Apophyseal lesions from Tendon Traction In the child and adolescent, one of the most common sites of acute apophyseal lesions is the pelvic ring , an area where several muscle-tendon structures find their attachment, thu s pred ispos ing the immature bone to a wide range of tract ion injuries. The apophyses of the pelvis, which are most frequently involved, arc : the secondary ossification center of the iliac crest, on which the muscles of the abdominal wall insert the anterior inferior iliac spine , from which the sartorius and the tensor fasc iae latae arise the anterior inferior iliac spine, which gives off the rectus femoris tendons the pubis , to which the adductors are attached the isch ial tuberosity, on which the hamstrings insert the lesser trochanter to which the iliopsoas tendon anchors. Avulsion injuries at the anterior superior iliac spine, at the origin of the sartorius and the tensor fasciae latae muscles are typically observed in adol escents and are usually secondary to a forced extension of the hip while the knee is flexed . In general, this kind of avulsion creates symptoms that are less severe and debilitating than those that occur at other pelvic sites. Anteroposterior radiograph of the pelvis shows a fleck of bone avulsed from the anterior inferior iliac spine: the fragment is usually small in size (normally <2 em) and has a triangular aspect. If the fragment is barely dislocated, the lesions can be difficult to recognize radiographically. With chronic lesions , hyperostosis and deformity of the anterior inferior iliac spine may occur. If the injury is quite old, the bone can assume a teardrop shape (teardrop sign) as a result of irregular reattachment of the fragment. US and MR imaging can show an avulsed fragment (that on occasion can be palpable), which is most often in continuity with the sartorius tendon rather that with the tensor fasciae latae. Avulsion injuries at the anterior inferior iliac spine are more common than those

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affect ing the ant erior supe rior ilia c spine . Th ese injuries occur at th e origin of the direct tendon of th e rectus femoris, a structure which is much more ex pose d biomech anicall y than th e sartorius . The traum a mech an ism is simi la r to that producing injuries around th e anteri or supe rior iliac spine, being du e to a forc ed exte nsi on of th e hip . Th is very common cond ition occurs not onl y in the adol escent but also in the child, and is oft en assoc iated with socce r and run ning ac tiv ities. In gen eral , pla in films demonstrate an area of cortical avul sion of less than 2 cm in size inferiorly to th e iliac spine, and exte rna l to the marg in of the acetabulum. Th e lat eral displ ac ement of th e fragm ent is related to th e ac tion of the ind irect tendon of the rectu s femoris, whi ch becomes prevalent when the di rect tendon is disin sert ed (Fig. 3.3). Th e avul sed bon e can be confuse d with the adjacent iliac bon e on ante roposterior radiog ram s: obl iqu e or axial view s can , therefore, be useful if thi s lesion is suspectcd on clinical grounds. For lesions in the pre-adol escent age (und er 10 years), US and MR imag ing can pla ya rol e in iden tify ing purely chondral fragm ent s without dislocation, whereas radiography may remai n negative (Figs. 3.4 and 3.5) . In doubtful cases, the same imagi ng mod alities can allow distinction betw een an apoph yseal dislocation of the ant erior inferio r iliac spine which ha s migrated inferiorly, and a dislocation of th e anter ior infe rior iliac spine . In mo st cases, the treatment is con servative, as the deg ree of dislocation is only mild, due to the re sistance offe red by the int act indirect and reflected tendon components. Avulsion inj uries ofthe apophysis ofthe iliac crest at the insertion of the mu scle s of the abdomina l wall are typically ob served in adoles cents pract icing sporting activitie s before the apophys ea l nucleus has fused . It should be taken into account th at the apophys is of the iliac cre st star ts to ossify at the age of 15 yea rs and is fused at the age of 18 years. Most avulsion tears of the apophys ea l nucleus of the ili ac cre st

Fig. 3.3 Avulsion fracture of the anterior inferior iliac spine. The anteroposterior radiogram demonstrates anomalous bone at the level of the anterior inferior iliac spine (arrow) as a result of previous traction trauma

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Fig.3.4 Avulsion of the anterior inferior iliac spine. a Sagittal US image (17-5MHz) of the normal anterior inferior iliac spine (AIlS) on the contralateral side of the lesion, shows the direct tendo n (arrowheads) of the rectus femoris muscle that arises from an apophyseal surface that is still cartilaginou s. The apophysis has a flattened ossification center (arrow). b On the symptom atic side, avulsion and rotation of the secondary ossification center is seen in continuity with the tendon of the rectus femoris. Between the avulsed nucleus and the base of the apophysis, heterogeneous cartilaginous tissue (curved arrow) due to hemor rhage and local edema is seen. c, d Axial fat-suppressed tSE Tz-weighted (c) and GRE Tz" (d) MR images show diffuse signal hyperintensity at the level of the anterior inferior iliac spine (arrow) and iliac bone adja cent to it (asterisk) . On the GR E sequence, note signs of bone fragmentation (white arrowheads) on the affected side, which are not visible on the contralateral side (open arrowhead)

Fig. 3.5 Avulsion of the anterior inferior iliac spine. a Sagittal fat-suppre ssed tSE Tz-weighted MR image over the anterior inferior iliac spine reveals a large piece of bone (arrow) avulsed from the anterior inferior iliac spine (open arrowheads), in continuity with the rectus femoris muscle (asterisk). b Note the perifascial and intramu scular reactive edema (white arrowheads). c US demonstrates deformity of the anterior inferior iliac spine (arrows), related to avulsion trauma, and signs of muscle edema in the rectus femoris (1) and the iliopsoas (2)

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deri ve from rep eated tr auma associate d with a n acute direct tr auma to the iliac cres t, or, eve n more commonly, a sudde n to rsion of th e body (tenn is, soccer). Th e dislocation typicall y occurs anteriorl y, n car th e ante rior in fer ior iliac spine, with lat eral slipping of an a pophyseal fragm ent of var iabl e size . Th e se gme nta ti on of th e apophyseal nucl eu s of th e iliac cres t is not a rel evant fi nd in g as it is obser ved in normal subjects . In some ca ses, th is condit ion is bil at eral an d ma y create probl ems in th e differ ential diagnosis between a normal state and a minimall y displaced lesion. MR imagi ng ca n show T2-sign al hyp erinten sit y in th e growth cart ilag e of th e iliac crest, and ede matous ch anges in th e soft-tissues located above and below th e avulse d fragm ent an d at th e lev el of th e mu scl e insertions (F ig. 3 .6) . Apophyseal avulsions f rom the symphysis pub is and th e inferior pub ic ramus at th e origin of th e adductors (adductor longus, adductor brevi s, adductor magnus, gracil is) an d th e rectus abdominis arc secondar y to e ithe r mi erotraum a or re peated traction with an exce ssive rot ation of th e bod y or during resi sted abduc ti on of th e th igh (e.g . two pla yers kick ing th e ball at th e same tim e) . Soccer and tennis a rc th e spo rt-

Fig.3.6Avulsion of the nucleus of ossification of the iliac crest. a Plain film shows sliding of the most anterior part (arrowheads) of the nucleus of ossification of the iliac crest, which appears lateralized and anteroinferior (arrow) in location relative to the rest of the same nucleus. b Coronal fat-suppressed tSE To-weight ed MR imaging shows the nucleus (arrowhead) dislocated laterally to the iliac bone (asterisk), in continuity with the external oblique (straight arrows) and transverse abdominis (curved arrow) cranially, and the tensor fasciae latae (TFL) caudally. The intense perifascial edema makes it possible to distinguish the profile of these muscles, which are dislocated externally by the avulsed nucleus. Note the spared internal oblique and the gluteus medius (Gill)' c Biomechanics of the avulsive lesions of the nucleus of the iliac crest. Observe the position of the aponeurotic insertions of the internal oblique (I), transverse abdominis (2), and external oblique muscle (3) on the ossification nucleus of the iliac crest. The schematic drawing on the right corresponds to the case shown in b

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ing activi t ies most commonly as sociated with thes e injuries. Dep end ing on the seve rity of trauma, di stingui shing adductor injuries from oth er caus es of pub algia, including ost eit is pub is, sacro-ili itis, hernias, and lesions around the hip and the ac etabular lip may be not strai ghtfor ward. In mo st ca ses, a true bon e avuls ion do es not occur, as the detachment sel ectively involves the tendon. Radiography can , th erefore, be negative in th e acute phas es; on th e oth er hand , in a chronic setting, sclerotic changes in the pub is can be identified at the level of the tendon inse rt ion. US and MR imaging are abl e to identify the retr act ed tendon end and to distinguish an is olated lesion of the adductor longus from extended traumas invo lving mor e than on e mu scl e. Avulsion injuries of the ischial tuberosity are re lative ly common. Th ey derive from an ex cessive ecce ntric contract ion applied from th e long head of the biceps femoris, the sem it end ino su s and the semim embranosu s, which arise from it. In general, these injuries are associated with int en se sport load as they occur during racing or activities involving forc ed flexion of the thighs on th e pelvis (e.g. gymn asti cs, dance) . The trauma is felt by the patient, with a sen sat ion lik e "a kick rec eived on the back" , which lead s to inte nse pain in th e glut eal region and the poster ior as pe ct of the thigh , mak ing walking difficult (Fig. 3. 7). In ca ses of mild apophyseal d isp lac ement , a thin elongated bony fragm ent which recalls the degr ee of curvatur e of the ischium (ischium ep iphy sio lysis) can be identifi ed. Thi s may be not easily recognized

Fig. 3.7 Ischial apophysitis. a Radiography and b coronal fat-suppressed tSE T2-weighted MR image show a lesion caused by chronic traction on the hamstring insertion (7) with swelling and deformity of the secondary ossification center (arrows) of the ischial tuberosity. The finding of subcondral sclerosis (arrowheads) demonstrates the chronic nature of the process, but the marrow edema of the tuberosity (asterisk) indicates that a recent trauma has also been superimposed

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on standard plain film s of the pelvis and may require an oblique view (ant eroposterior with 25-30° caudocrani al incl inat ion of the beam) to be seen . With major lesion s, radiography shows a large apophyseal fragm ent whi ch is avulsed and dislocated caudall y, far away from the ischium. In the chroni c pha se, and in pat ient s with per sistent dis ability, MR imaging can reveal a fibrous bridge inter vening betw een the avulsed fra gme nt and the ischi al tub ero sity (Fig. 3.8) . The form ation of a hypertrophied callus at th e level of the ischium and of the adjace nt heterotopic bon e should not be confused with an aggressive lesion such as osteom yelitis or Ewing 's sarc oma. In larg e avulsi on injuries , the clo se re lations hip betw een the origin of the ham str ing s and the sciati c ner ve can lead to a nerve-stretching inj ury in an acute pha se (hamstring sy ndrome) or in its entrapme nt by scarr ing tissue in th e chronic phase. In the instanc e of trauma about the ischial region , the occurrenc e of irr itating sy mptoms in the territory of the sciatic distribution requ ires furth er MR imaging examina tion to rul e out any nerve abnormality. Avulsion inj uries of the small trochant er at the inse rtion of the iliop soas tendon are rare, and can be mo st oft en found in adol escent s before th e clos ure of the apophyseal growth cart ilage. Th e bon e detachm ent , which is seconda ry to an ecce ntric contraction of the iliopsoas with exte nded thigh , can be see n rad iog raph icall y as a separation and crani al retraction of the apophysis of the sma ll trochanter, or as a widening of the growth cartilage layer. In doubtful cases, MR im aging ca n displ ay bone and chondral edema at the apophysis by me an s of heavily Tj-weighted sequences . A thin effusion can occ asion ally be seen track ing alongsi de the iliopsoas tendon. In the pedi atric age group, the knee is another area of the body th at is often involved by apophys ea l avulsions from tendon traction. Typical injuries are sleeve fracture of the patella and avulsi on of the tibi al tuberosity .

Fig. 3.8 Avulsion of the ischial tuberosity. a Radiography shows a large-sized bone fragment (arrow) detached from the ischial tuberosity. The fragment derives from chondral avulsion, which

was subsequently ossified. b Coronal ORE T2* MR image show the bone fragment embedded in the hamstring tendons (arrowheads)

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Sleeve fractures of the patella are avulsions of a thin bony edge (often difficult to see using x-rays) from the upper or lower pole of the patella attached to a more extended slab of articular cartilage. Clinically, this lesion presents with full knee disability, is observed with a peak incidence between 8 and 12 years of age, and is secondary to the traction exerted by the quadricipital or the patell ar tendon on the poles of the patella, which are not yet ossified. Such sleeve fractures occur as a result of specific biomechanics (both tendons insert on the anterior side of the patella) and on the basis of the fact that , during the maturation process, the growth cart ilage seems to be, at this stage , more vulnerable than the underlying bone. If the avulsion extends posteriorly to involve the articular cartilage, the fracture is intra-articular in locat ion and associated with hemarthrosis. US can confirm the lesion by showing the avulsed chondral component, which is predominant compared with the bony one, and the tendon inserted into the detached fragment instead of the patella. Similarly, MR imaging can reveal bone marrow edema in the patella, and is able to demonstrate the avulsed chondral component and to differentiate it from the effusion (owing to a lower Tz signal intensity) and the bony component (gradient recall ed echo [GRE] sequ enc e). The treatment for undisplaced fractures «4 mm) is conservative, with the knee blocked in extension with a brace or soft cast. If displaced (>4 mm), the sleeve fracture of the patella requires surgical reduction, re-alignment of the joint surfaces with or without internal anchoring, and reconstruction of the extensor mechanism. Avulsion injury of the tibial tuberos ity occurs when the traction applied to the extensor apparatus by the patellar tendon during rapid acceleration or deceleration phases exceeds the resistance offered by the physis and the perichondrium/ peri ostium. This injury can be considered the extreme of the spectrum of the class of lesions which include, at the other extreme, Osgood-Schlatter disease . The maturation of the tibial tuberosity can be divided into four successive stages: I. cartilagineous, in which the tibi al tuberosity is fully chondral 2. apophyseal, in which an ossification center appears in the tuberosity (in girls at approximately 8-12 years of age , in boys at 9-14 years) 3. epiphyseal, in which the secondary ossification centers of the tuberosity and the proximal tibial epiphysis join to form a continuous bony bridge 4. mature bone, in which there is bony closure between the tuberosity and the metaphysis of the tibia. Avulsion-fracture of the tibial tuberosity can be divided into three types based on the distance of the fracture edge from the top of the tuberosity (according to Watson-Jones): in type 1, the fracture line passes through the distal part of the physis of the tuberosity and involves the nucleus of ossification in type 2, the fracture line separates the ossification centers of the tuberosity and the tibial epiphysis in type 3, the fracture extends into the proximal tibial epiphysis and involves the knee joint.

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Sinc e the tub ercl e lies in a slightly lateral po sit ion relative to the midl ine, plain film s should be obt ained in slight intern al rotation . Type 2 and type 3 lesion s require surgica l reduction and stabilization . In the arm , the elbow is th e mo st common site of apophyseal avulsion by traction mech anism. The medial epicondye (epitrochl ea) , with its apophysea l nucl eu s, is particul arl y vuln erabl e to biom echanical stresses as it gives origin to multiple tendons (common flexor tendon origin and pron ator teres tendon) and ligam ent s (medi al collat eral ligament) . Avul sion of th e ossification cent er of the medi al epicondy le is mor e common in th e USA rather than in Europe, due to the common prac tic e of ba seball in school-aged boys (so-call ed " litt le league elbow" ). In th is sport, th e trauma occur s dur ing repetit ive overh ead throwing motion s (pitching) . This cau ses a valgus stress on th e elbow joint , which causes damage to structures at the medial epicondy le of the hum erus, par ticularly the growth plate. Of course, similar overload can be exerte d in oth er sports that involve laun ching obj ect s (e.g. javelin, handball) as well. The appl ied stress is parti cularly strong using techniqu es to pitch "cur ve" balls: this is the reason why the use of these techniqu es is forbidd en in the age range between 9 and 14 years, when the nucl eus of os sification has not yet fused. The repeated microtraum a can lead to acceleration of the epic ondy lar growth , tract ion apophysiti s with bon e fragmentation, and apophys ea l det achment (Fig . 3.9) . Tre atment is con serv at ive for undi spl aced «5 mm) lesion s; surgery is required for displ aced (>5 mm) injuries and involves reconstruction of the medial coll ateral lig ament and anchoring of the medi al ep icondyle.

Fig.3.9 Avulsion of the secondary ossification center of the medial epicondyle. a In the acute phases of trauma, anteroposterior radiography shows diastasis between the humerus and the secondary ossification center of the medial epicondyle (arrow). b Follow-up radiogram reveals an intense periosteal reaction (arrowheads) over the ossification center

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3.3 Ligaments From both an an atomic an d a fun cti ona l point of view, th e ligament s of ch ildren and adoles cen ts are int rinsically mo re lax than those of an adu lt, and thi s lead s to some j oint hyp erext en sib ilit y (Fig. 3.10). Upon reaching adulthood, th is lig am ent laxity, wh ich tend s to be particularl y acc entuated in females during pub ert y du e to ho rmonal influenc es, tend s to redu ce progressively with a corresponding incre ase of j oi nt stabi lity. In it self, the laxity protect s lig aments from po ssib le spra ins, but cannot be considered re ally protective for the joint, since it lead s to a ce rt ain degree of ins ta bility. Ap art from these cons idera ti ons, lig ament inj ur ies in chi ldren mo st often invol ve the atta chm ents into the immature bone , rather th an the ligament subs ta nce . US ex am ination of lig aments in ch ildren is only po ssible at ce rt ain body ar eas and, of course , only when the ligament is exposed to the US be am through adequa te acous tic w indows. US allows a dyn am ic study du ring lig ament ten sion ing or loo sening , thus identi fying injuries with lig ament elongation without rupture . MR ima ging is mandatory to evalu ate some deep-se ated intra-articul ar lig aments, such as the anteri or cruciate .

Fig.3.10 Bursitis of the medial collateral ligament of the knee. a Coronal ORE T 2* MR image, and h corresponding US image show prominent fluid distension (asterisk) of the medial collaterall igament bursa, with separation of the superficial component of this ligament from the meniscofemoral and meniscotibial components (arrowheads) that overlie the condylar cartilage and the meniscus (arrows). Such a high-degree separation in the components of the medial collateralligament is rarely encountered in the adult population and can be regarded as an indirect sign ofligament laxity in children and adolescents

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3.3.1

Apophyseal Injuries Due to Ligament Traction Although all ligament s can th eor etically be th e targ et of traumat ic injuri es in children , most lesion s invol ve the ankle ligam ents following inversion traumas, the medial collate ral ligam ent , and th e ante rior cruciat e ligam ent of th e knee in association with a fra cture of the int ercondylar emi nence . In th e school-age d child and adoles cent, th e ligament s of the lat eral compartment of the ankle are commonl y affected during inver sion sprains. In most cas es , th e pathologic mech an ism involves sudde n changes of dir ect ion wh ile runn ing , as happ ens in socc er, basketb all , or jumping sports . The anterior talofibula r liga ment is by far th e mo st commonly damaged ligam ent. US demonstrates th e avuls ion of an osteochondral fra gments of sma ll size at th e level of the insertion (fibular) of the ligament , rather than a defect of continu ity of the ligam ent f iber s (Fig . 3. l la, b). Oft en , th ese fragm ent s are entirely cartilag inous and cannot be seen on plain f ilms. Thi s is th e re ason why ligam ent lesion s can be confused with Salt er-Harris type I fra ctures. The fate of avulsed fragm ent s is twofold. If th eir size is small and th eir posit ion is adj ac ent to th e avuls ion site, newl y appose d bon e will fill th e distanc e between them and the bone, rea bsorbing the avuls ion . On the other hand, if the osteochondral fragment is displ aced far away from the nidu s of avulsion, thi s can lead to progressive ossification and g rowth of the fragment within the lig ament, to cre ate an ossicle ( Fig. 3.11 c-e) . In general , the le sion of the anter ior talo f ibul ar lig ament is isol ated and US is suff icient for the diagnostic work-up . Ultrasound is unable to evalu ate fra ctures of the intercondylar eminence of the tibia, at the di stal insertion of the anterior cruciate ligament. These fractures are normally encountered between 8 and 14 year s of age and are the consequence of a hyperextension mechan ism of the knee, with or without ass ociated later al stress force s or rot ational components. The se fractures often occur after the patient has fallen from a bicycle or ha s a knee sprain while ski ing, or they may be the consequence of direct traum a on the di stal femu r when the knee is flexed . The classification of fractures of the intercondylar eminence (according to Meyer s-McKeever) is based on the degree of di sloc at ion (Fig. 3.12 a): in type 1, the fracture line has a hori zont al course and occurs at the base of the anterior port ion of the osseou s eminence with slight rising of the anterior edge of the fra gment in typ e ll, the inte rcondyl ar em inence is raised and angled posteriorly relative to the tibi al plate au , but still in continuity with it in type lIlA , the eminence is completely avulsed by the tibi al surface but is not angled (Fig. 3.12b -d) in typ e IllB , the intercondy lar em inence has completely separated from the tibia, and is ra ised and rot ated posteriorl y. Although th ese fractures can be iden tif ied on standa rd ante roposterior or lateral vie ws, obliqu e proj ections for the intercondylar sulcus demonstr ate th e avul sed bon e much bett er. In doubtful cases, a useful indirect sign for the diagnosis of type 1 lesion s is detection of a distend ed supra-pate llar recess with a fluid-l evel app earance

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Fig.3.11 Anterior talofibular ligament sprai n. a, b , Recent tra uma. US image (a) and corresponding radiograp h (b) show avulsion of a thi n cortical layer (arrowheads) from the latera l malleolus, in continui ty with a swollen but continuous ligament (arrows). c-c Old trauma. US (c), radiogra phy (d) and T i-weighted MR imaging (c) demonstrate a large ossicle (arrow) with regular margins embed ded in the ligament (open arrows)

Type I

Type II

Type III

Type IIIB

Fig. 3.12 Fracture of the intercondylar eminence cause d by anter ior cruc iate ligament traction . a Class ification acco rding to Meyers-McKeever (see text). b-d Type ili A lesion. Standard lateral radiog ram (b) and CT scan with sagitta l reconstruction (c) and 3D rendering (d) show avulsion of a large intercondylar frag ment (arrow), with para llel orientation to the tibial plateau

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(lipohemarthrosis) . In children , th e av u lse d fragmen t can be a lm os t enti re ly made of ca rt ilage . MR im agi ng shou ld be used not onl y for bone and cru ciate ligament assessm ent but al so for the study of a sso c iated les ions, su ch as m eni sc al or m edial collat er al lig am ent tears, whi ch are frequently see n as asso ciated find ings in th e ad olesc en t. Surger y is indicat ed in typ e III les ions. Th e outcome is favo ar able . On th e other hand, avul sion fracture at th e tib ial in sertion of th e po st erior cruciat e ligament is exce ptio na l.

Suggested Readings Bates DG, Hresko MT, Jaramillo 0 ( 1994) Patellar sleeve fracture: demo nstration with MR imaging. Radiol 193:825- 827 Gottsegen CJ, Eyer BA, White EA et al (2008) Avulsion fractures ofthe knee: imaging findings and clinical significance. RadioGraphie s 28: 1755-1 770 Hirano A, Fukubayashi T, Ishii T et al (2002) Magnetic resonance imaging of Osgood-Schlatter disease: the course of the disease. Skeletal Radiol 31:334-342 Hogan KA, Gross RH (2003) Overu se injuries in pediatric athletes. Orthop Clin N Am 34:405--415 Pisacano RM, Miller TT (2003) Comparing sonography with MR imaging of apophyseal injuries of the pelvis in four boys. AJR Am J Roentgenol 181:223- 230 Rossi F, Dragoni S (200 I) Acute avulsion fracture s ofthe pelvis in adole scent competitive athletes: prevalence, location and sports distribution of 203 cases collected. Skeletal Radiol 30:127-131 Sanders TG, Zlatkin MB (2008) Avulsion injuries of the pelvis. Sem Musculoskel Radiol 12:42-53 Stevens MA, EI-Koury GY, Kathol MH et al (1999) Imaging feature s of avulsion injurie s. RadioGraphics 19:655-672 Volpon 18 , de Carvalho Filho G (2002) Calcanea l apophysitis: a quantitati ve radiographi c evaluation of a secondary ossification center. Arch Orthop Trauma Surg 122:338-341

Major and Minor Pediatric Traumatic Musculotendinous Injuries E. Cenovese.A. Leonardi, L. Callegari, I\I.G. Angcrclli. 1\1.Alhrizio, E. Spa no and C. Fugazzola

4.1

Introduction

Tendi no us insertions on apophyses, artieul ar surfaces and epiphyses are " weak po int s" in the mu sculoskel etal sys tem of childre n du e to th e presen ce of growth plates, and th ese areas are particularly vulne ra ble to traumatic lesion s. Although traum at ic lesion s of mu sculotend inou s and ligam entous soft tissu e are not common dur ing th e growing years, th eir inci dence has risen, probabl y as a result of an increase in sporti ng act ivit ies in th is ag e group. Some authors beli eve that, dur ing growth, mu scular development is slower than that of long bon es and that th is pred ispo ses to mu scul ar lesion s suc h as sprai ns and, though less likely, mu sculotend inou s strain lesions. Furthermore, during pedi at ric ag e, tendons are usually more resi stant to damage than th e car tilag e and bon e on wh ich th ey are inser ted. Th er efo re tendon tear s are not as fre que nt as in young athl et es wher e it is common to diagnose abnorma lities du e to overload (ins ertional tend inopath ies , bur sit is, tendonit is). Finall y, acute lig am entous lesions are rare in ch ildren because of the elas tici ty of articular stru ctures , whereas th ey ar e common in athletes .

4.2 The Role of Imaging in Detection The majority of the se lesions ar e di agnosed with ana mnes is and phy sical examination. Imag ing techniques are useful to confirm a working di agnosis, and to loc al ize

E. Genovese (C8J) Department of Radiology, Circolo Hospital Macchi Foundation, Varese, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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the damage, define its extension, detect comorbidities and, above all, for prognostic reasons. Ultrasound (US) is the gold stan dard in the study of musculotendinous disease. Ultras ound evaluatio n, usually using high-frequency (7- 15 MHz) linear probes, allows a high-r esolu tion ana lysis of the anatomical clements in their path. The idea l evaluation is comparative and in dynamic phase. Color/power-Doppler integrati on allows visualization of concomitant vasc ular lesion s and the presence of hyperemia, if any. Skel etal mu scle present s a regular "toothbrush" struc ture due to the regular alternation of type III fi bers (hypoec hogenic) and of the perimysium (hypere chogen ic). Every muscle is delimited by a thin hyperechog enic layer which is the epimysi um; superf icial fasc ia, between the subcutaneous layer and mu scle, has the appearance of a thin hyperechogenic interface , whereas the bone is represe nted by a strong ly echogenic line followed by high attenuation of the ultrason ic beam. The tendon has a hyperechogenic f ibri llar echostructure due to various interfaces between collagen fibers and endoten dinous septa. It is delimited by an echogenic thin line, the external sheath, which assum es the identity of peritenonium for anchor tendons (i.e. Achilles ' tendo n, patella r tendo n, etc) and a synovial peritend inou s sheath for slip tendons. It is important to emph asize that US scan, with the aid of stress maneu ver s of the area under examin ation, is the fir st-l ine investigation for the extr a-articul ar ligament s, which are commonly seen as a thin hype rechogenic, homogeneous str ucture adjacent to the bone profile. Magnetic resonance (MR) is usually the second-line investigation. Because MR examination s are mult iplanar and mult iparametric, MR is an important diagno stic tool where there is suspicion of lesion s involving contiguous skeletal structures (hidden fractures, apophyseal avulsi ons, osteochondral lesions, apophysitis, stress fractures), joints, blood vessels or ner ves, and in tho se cases where preope rative planning becomes nece ssary. Thank s to its wide range of view and high sensitivity, MR is indicated in all musculotendinou s and ligamentous lesions that are too deep to be seen with US. In detail , the ideal MR protocol for traumatic mu scul ar lesion s star ts with a coronal comparative high-re solution acquisition that is able to identify the abnormality in its exten sion [proton density (PO) , fat saturation (FAT SAT) or short tau invers ion recovery (STIR)] through the vis ualizati on of edem a and hemo rrh age . Then high- contrast axial acquisi tion (fas t spin echo (FSE) proton den sity (PD)/ T2) is carri ed out to identify the damaged muscle , the lesion exten sion , and its relation to the perimu scular and intermuscular fascia e. Axial T I acquisition enables the clinician to distingu ish between fibrosis and calcifi cations. In addition, in a subacute phase, hemoglobin degradation products can make the hemo rrh age hyperintense so that it can be distinguished from edem a which is hypointense. In elinical practice, x-ray is only indicated for the diagno sis of distortion traumas when an associated bony injury is suspected, or as a diagnostic aid where pathogenetic

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osteo-articular factors (bon e misalignments, dimorphi sms , anatom ical variant s) are suspected.

4.3 Muscular Lesions Traum atic mu scul ar lesion s can be div ided, according to the type of traum a, into distract ive lesion s (ind irect traum as) due to longitudinal force s that overcome the elastic resistance of the muscul ar fibers, and contusion lesion s (d irect traum as) due to external ca uses. The immediate effect of a traum atic lesion is dam age to muscle fibers, coll agen , and elastin , together with damage to capilla ry vessels, arterioles, and venules; the acute infl amm ation tr iggered by thi s proce ss lasts approximately 24-4 8 hou rs. The process of rep air could lead to "restitutio ad integrum" , or replacement of tissue with connective tissue , and fibrosis .

4.3.1

Muscular Distractive Lesions These involve the mu sculotendinous unit and can occur in the muscle belly or, mor e often, at the musculo tend inou s j unction. These lesions are parti cul arl y common in sports where mu scles are maximall y strai ned; they occur mor e often at the beginning of the sport sess ion and mor e frequentl y involve those muscles of the lower limb s that participate in the movement of two joints; in some cases, less frequ ently in pediatr ic age, these lesion s occur at the level of the adductors : these muscles have ecce ntr ic-ty pe contractions even though they are not involved in two joints. Three degrees of cl inical cl assification exist: a mild (elongation) lesion me ans rupture of few muscle fibers with stiffness and light swelling of the ent ire mu scle ; a moderate lesion (parti al rupture) con sists of tissue dam age in up to two-thirds of the muscle belly, and its symptoms and signs are acute pain that is sudden and well locali zed, with loss of function; a seve re lesion (complete rupture), typ ical at junction al level , involves the enti re mu scle thickness and the symptoms are severe pain with complete loss of function. In this case, when the mu scle is superfi cia l, palp ation can reveal a gap area due to retraction of muscle tissue in the rup ture zone; thi s is generall y ac companied by bleeding that may spread up to the surfac e and pre sent as ecch ymo sis. Ideally, US scan should be performed between 2 and 48 hours after the lesion . In fact, during the fi rst 2 hour s the hematom a is sti ll build ing up, whereas after the 48th hour the hemorrhage may have spread beyond the muscl e. The Peetrons class if ication divid es mu scul ar lesion into four grades from an echographic po int of view:

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grade 0: absenee of so nographically detectabl e lesi ons grade I (co rrespon ds to the elongati on) : hypoechogen ic im a ge, du e to pr e sen ce o f small ar ea s o f se rohe matic in fi lt ra ti on wi thi n th e muscl e, m easur in g mo re than

5% o f th e mu scl e volume (F ig . 4.1 a) gra de II: in ter ru pti on o f muscl e fi bers w ith a hypo-anechogenic gap which c orre sponds to dam ag e of 5-50% of th e muscular vo lume on the ax ia l plane; in th is ca se th e com p ressi on effe ct of th e probe could show flu ctu ant fib er fragments in a seroche m atic flu id (Fi g . 4 .1 b) gra de Ill: compl et e muscular lesion s w ith d istal e nd retract ions or le sions invo lv ing more than 50% o f th e muscl e , asso c iate d w ith flu id pool an d po ssibl e in termu scular ex te nsi on of th e h ematoma wh en th e lesion invol ve s th e apone urosis (F ig . 4.1 c) . Possible M R a ppearances o f mu scular lesions a re g rade d a s follows:

Fig.4.1 Echographic appearance of various grades

of muscular lesions. a Elongation or grade I distractive lesion. The longitudinal US scan of the pre-insertional region of the medial gemellus muscle shows abnormal echogenicity of the superficial muscle fascicles. At lesion level, an area of diffuse hypoechogenicity is due to the presence of edema and blood (arrow). The edema also involves the epimysial fascia, which appears hazy. b Partial muscular tear or grade II distractive lesion. Longitudinal US scan along femoral biceps muscle shows inhomogeneous abnormal echogenicity, mainly hypoechogenic, which corresponds to an area of fiber tear and hemorrhagic infiltration (arrowhead). c Complete muscle tear or grade III distractive lesion. Longitudinal scan on the rectus femoral muscle shows tear of the whole belly with retraction of the tear end (arrow) and a massive anechogenic fluid pool (curved arrow )

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grade / (corresponds to elongation an d sta ge I according to the ec hographic clas si f ica ti on): in long-RT (rep etition tim e) sequences it appe ars as a hyp erintens e foc al signa l with ha zy margin s du e to ede ma an d hemorrhage (Fig 4.2 a-c) grade II: partial mu scl e rupture, with hemorrhage and ede ma. Int errupted mu scl e fib er s can be see n in th e form of a cl ear hyp er int en se area in T2 sequenc es (Fig . 4.3a-c) grade 11/: compl ete rupture of mu scl e fib ers with ret raction ; it can be seen as a hyp er int ens it y in T2 du e to hemorrhage, oft en organi zed as hem atoma. It is associated with ed em a within and around th e muscl e, sometim es with perimuscular and int erfasci al flu id. Th e MR app earan ce of the hematom a changes as time passes: in th e hyp eracut e phase (w ithin 48 hours) , it app ears is oi ntense with respect to th e mu scl e in T) and hyp eri nt en se in T2 with or without fat suppress ion. In th e subac ute ph as e, th e hematoma pr es ents hyp erinten sit y in T) and T2 an d it is delimited by a hyp erint en se border; th ese signal changes are du e to th e pr es enc e of hemoglobin degradation products. In th e chronic phase, th e hem atoma becom es hypointen se in both T) an d T 2.

Fig.4.2 MR picture of a grade I distractive lesion of the left semitendinosus muscle. FAT SAT r, (a) and FAT SAT PD (b) sequences show a small hyperintense area with hazy edges within the belly of the muscle; this is due to edema and hemorrhage (arrowheads). This finding is not recognizable in the spin echo (SE) T) acquisition of the axial plane (e)

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Fig.4.3 MR appearance of a grade II distractive lesion of a left semimembranous muscle (partial musclc tear). FAT SAT PD (Proton Density) on coronal plane (a) and FAT SATT2 (b) on axial plane acquisitions reveal an irregular hyperdense area which corresponds to a small blood pool due to the rupture of a small amount of tertiary fibers (arrow), with association of interstitial edema (arrowhead) . SE T, sequence of the axial plane (c) shows a small area of hypointensity at the same level (curved arrow)

In a few cases (fo r example in pediat ric ag e when femoral perio ste al stripping is pre sent), par am agnetic contrast med ium can be use ful for differential diagnosi s of traumatic and neopl asti c lesions. In exception al circ umstanc es, the contrast medium ca n be used in young ath letes in cases of di ff iculty in gradi ng , in particul ar in low- gr ade lesion s. In fact in T I acq uis iti ons, contrast enhancement ca n show th e true extent of the mu scl e dam age , di fferenti ating it from the peril esion al ed em a .

4.3.2 Muscular Contusions Th ese lesions, the mo st co mm o n in pedi atric age, es pecially in con ta ct spo rts, usually inv olve muscl es of th e lower limb s (partic ularly the q ua dri ce ps and an terior tib ial m us cles) . Th ey present as swe ll ing , con tracture, j oi nt sti ffness, an d pai n, both spon tane ous an d palpat io n/mo vem ent ind uce d. Imaging of th ese lesion s is th e same as tha t describ ed fo r di stractive lesio n s, altho ug h th ey are deep er, du e to thei r m ech a ni sm (u p to the bo ne level) .

4.3.3 Complications and Follow-up In th e acute ph ase, compartment sy ndrom e is an important potenti al complication . It is cau sed by a ris e in inters ti tial pre ssure within a mu scular compartment bounded by an un st retchable common fas cia .

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Oth er poss ible compl icat ions could be lesion relapse, intermuscular effusion, muscula r pseudo cyst, post-tr aumatic fibro sis, and ossification. In particul ar, the complex picture of myositis ossificans is the result of an extensive ossificat ion process within the scar tissu e present in a non-compl etely absorbed hematom a. Imaging in thi s case can var y and can differentiate different lesions, including neopl asias. MR can show an aspec ific mass extended to different muscle group s; calcific ation s are not well visualize d, therefor e, in these cases, X-ray can clar ify the pictur e, whereas computed tomog raphy (CT) is for selected cases, particularly in relation to patient age. US is reliable for monitoring the heal ing process and early detection of compl ications. MR is a second-line investigation in compl ex cases; in young athl etes this investigation is indicat ed to predict the time cour se of rehabilitation and return to acti vity; MR is able to ident ify resi dual fluid within fasciae as this is not a good prognostic factor. Furth ermo re, in these case s MR can differenti ate fibrosis from granulation tissue.

4.4 Tendon Lesions In some young athletes, mechanical overload lesions are a possible finding. The pathogenesis of the se lesion s is rep resented by long standing microtraumas in an anatomical area, due to inten se training with overload on norm al structures subj ected to abnormal loads, sometimes as a result of congenital or postur al causes (devi ation of the exten sor appara tus alignment, abnorma l torsion, varu s or valgu s knee , pes planu s or cavus, etc). Even though the weak point at this age is the growth plate, the se lesions can occur at tendon level. All the different tendon components (tendon body and its external sheath, musculotendinous junction, enthesis, and bursae) are subj ect to different abnormalities of different inten sity.

4.4 .1

Tendinopathy The se abnorma lities pre sent with the same set of symptoms : pain, local peritendinou s swelling, antal gic limitation of function. Class if ication is difficult due to the different forms of tend inop athy. However, four abnorma lities can be iden tified : I. paratendinitis, which involves peritend inous tissues (peritendonit is and tenosynovitis); in these cases US can show a hypoechog enic thickening of the peritenon iurn at the enthesis and a hypo- anechog enic fluid distension of the externa l sheath

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at slip-tendon level ; this is well recognized on MR with Tz-wcightcd sequences, as a hyperintense lin e around the hypo intense tendon 2. parat endinitis with tendinosis, including inflammatory and degenerative alterations of peri tendinous tissu es and of the tendon body 3. tendinosis, which is typ ical of adult age , and characterized by degenerative phenom ena and intr atendinous involution processes. In these cases, US shows a general increase of tendon volume, which presents hypoechogenicity, abnormal echostructure, and metaplasic calcific areas 4. tendonitis: various degrees of inflammatory changes within the tendinous matrix .

4.4.2

Insertional Tendinopathies (Enthesopathies) Thi s group includes clin ical pictures related to flogistic-degenerative involvement of the tendon insertion zone on the bone. Enthesopathies are the clinical manifestation of conditions such as impingement syndromes, traction tendinopathies that are typical of young athletes, so that some abnorma lities are identified with the mo st common sporting activity in which they occur (jumper's knee , tennis elbow, etc). Whatever the involved tendon, the US picture is typical : the enthesis is thickened, hypoechogenic, and has irregular echostructure; it may be associated with bursal flogistic distension, and, in an advanced pha se, hyperechogenic calcification can be found within the tendon at insertional and pre-insertional level. In these cases , MR is useful for evaluating peri tendinous structures (bursae, fat pads, fibrous tunnels) and can reveal if the abnormality is limited to musculotendinous structures or extended to the bone tissue - i.e. reactive osteitis visible as hyperintensity with hazy marg ins at spongious level in T2 acquisitions with fat tissue saturation (Fig. 4.4). During teenage years , enthesopathies associated with apophysitis are rare. This is because the tendon insertion does not occur directly on the bone but is on the growth plate, which is not as resistant as the tendon to mechanical forces du e to overload or trauma. The most frequent apophysitis occurring during teenage years is OsgoodSchlatter disea se. This involves the growth cartilage of the anterior tibial apophysis where the patellar tendon is inserted . Imaging is not absolutely necessary to confirm the clinical suspicion but it is important to recogni ze pred isposing conditions (low or high patella, external deviation of the patellar tendon, valgus knee, torsional abnormalities of the foot) . At present, US is able to completely replac e X-ray in diagnosis. In fact it can show the irregular and fragmented cortical profile of the ossification nucleus, thickening of the growth plate, patellar tendon enthesopathy, and deep infrapatellar bursitis. Possible complications of this syndrome (tibial tubercle avulsion, patellar tendon rupture, early ossification of tibial growth plate) should be considered severe, as they could influence the regul ar skeletal development.

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Fig.4.4 Insertional tendi nopathy of the posterior tibial tendon caused by a osteotendinous impingement syndrome. a With MR, SE T j sequence on a sagittal plane shows a small sesamoid bone at the tendon inserti on site (arrow) and a hazy hyperintensity ofthe tendon structure at the same Icvel (arrowhead). b T2gradient echo sequence of the coronal plane confirm s loss of the typical tendon hypointe nsity (arrowhead) and shows a clear signal hyperintensity of the peritendi nous structures due to edema (curved arrow)

Fig.4.5 Sinding-Larsen- Johansen syndrome. At MR FAT SAT T2 sagittal acquisition allows highlighting of the fragmentation of the inferior patellar pole (arrow) together with a hazy and inhomogeneous signal hyperintensity at the insertional portion ofthe patellar tendon (arrowhead) and a light edema of the Hoffa's fat pad (curved arrow)

Sinding-Larsen-Johansen disease is an osteochondrosi s asso cia ted with in sertion al tendinopathy o f the patell ar tendon at the inferior pole o f the patell a where the growth nucl eus lies . Th e X-ray picture is a fra g m entati on of th e patell ar inferior pol e, and U S shows th e typi cal appearan c e of an in sertional tend inopathy. MR can be useful for differ ential di agnosis (patellar fracture, stress frac ture , bipart it e patella typ e I, jumper 's tendonitis) ( Fig. 4 .5).

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4.4.3

Bursitis During pediatric age, involvement of bursae is usualIy secondary to an acute or chronic abnormality involving the tendon. Bursitis assoc iated with apophysitis is typic al but bur siti s with hemo rrhagic effusion due to dir ect traum as may also be seen. UsualIy, after a first acute phase with edematous thickening and inflammatory effusion, fibrosis can occur and this is responsible for the local friction that causes chronicity. Both US and MR are able to identify these abnormalities and differentiate them from cystic lesions of the synovial waII which are in communication with articular space.

4.4.4

Tendinous Ruptures Th ese are rare in ped iatric age and are generalIy associa ted with bon e avulsion s. However, in some cases, pers istent mechanical overlo ad could caus e partial or complete rupture at the ost eot end inou s inser tion level or within the tendon bod y. US can show interruption of the continuity of tendon fibers, where the hem atic component lies with various degrees of diastasis in the case of complete ruptures. Comp lete ruptures are easily seen at MR, whic h shows flu id and hemorrh age within the lesion. The se are strongly hyperintense in T2. MR can also show the degree of retr act ion of both tendon ends in ord er to plan the best treatm ent.

4.5

Abnormalities of Ligaments Ligaments can be classified into intra- and ext ra-articular. Thi s distinct ion is useful for a correct diagno stic approach .

4.5.1

Extra-articular Ligaments Symptoms of distractive traum as involving these stru ctures are cha racterized by pain , local swelling, funct ion limit ation , and various degrees of instability. US can distinguish acute lesions in three degrees of distortion :

grade 1: moderate ligament thickening at lesion leve l with diffu se hypo echoge nicity due to ed ema grade 11: ligament thick ening with intern al inhomogeneous appearance and hypo echogenic area s repr esenting th e laceration point associa ted with a small hematic poo l

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Fig.4.6 Muscle vastus intermedius fibers injured from blunt trauma in the acute phase. Longitudinal ultrasound scan shows a retraction of fiber ends and the presence of a large hematoma interposed (hypo-anechogenic collection) (arrows)

grade ll/: complete lig ament rupture, generally in the medi al tract ; in th is case, US is an excellent tool for showing retra ction of both end s and the pre sence of a large hem atoma whi ch can f ill the cap sule (Fig . 4 .6) . If the rupture is at insertional level with oste al-perioste al det achment, US should be integrated with other im aging technique s (mainly standar d X-ray) . Ankle spra ins are tho se mo st commonly rel ated to spor ting ac tivities . Inver sion and ever sion traum as commonly invo lve ligaments from the lateral compartment (in particular the anterior talofibular ligament). In th is case, completing the inve stig ation with MR could allow evalu at ion of the subta lar joint, wh ich is not easily visible with US, to high light po ssible oste al avulsions with per i-in sertional spongious edema and talar-dome-associ ated bony lesion s. Collatera l ligaments of the kne e are also commonly involved in traum atic di sto rsive lesion s, particularly in the medi al compartment. In the se cases, MR shows the involvement of the bone at insertional level, and oste al imp act lesions, and could exclude the typic al physeal fra ctures . In add ition, in ca ses of joint effusi on with blood, MR can confirm or exc lude the presence of ant erio r cruciate ligam ent- or meni scal-associat ed lesion s.

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Fig.4.7 Acute distractive lesion of anterior cruciate ligament (ACL). With MR, FAT SAT T2sagittal acquisition shows diffuse and inhomogeneous signal hyperintensity at the ACL site, due to interstitial hemorrhage but without fiber strain of the ligament (arrow). This picture is associated with joint effusion (arrowhead)

4.5.2 Intra-articular Ligaments In ped iatric age, knee distortion traumas are usually rel ated to complex hyperextension mechani sm s, sudden torsions during direct traum a. They commonly involve the anterior cru ciate ligament, who se le sion al pattern varies in rel ation to skeleta l matu rity. In fact in adulthood, Sharpey 's f ibers att ach ligaments directly on the bone, whereas in childhood co llagen fibers of the anterior cruciate ligament are fused with the perichondrium of the epiphysial cartil age ; th is difference expl ain s why tibial em inence avulsions , typical of the immature bone, do not involve the ligament. In phy siologic conditions, the anterior cruci ate ligament appears as a hypointense stru cture at MR . When traum a occurs, it can determine a part ial or complete (di ffu se or loc ali zed) laceration or a sha pe deform ation of the ligament without fiber strain; the level of the lesion can be prox imal (w ith det achment of the condyl ar insertion, with intr asynovial le sion or, rarely, with avul sion of a bone fragment) , medial (with focal lesion along the ligament) , or dist al (with or without bone avul sion) . During the acute phase, edematous and hemorrhagic phenomena produce loc alized or di ffuse swelling of the lig ament, which appea rs tortuous, and its marg ins are difficult to di stinguish from the surrounding fluid and synovial infl amm ation . In thi s ph ase, the ligament appears hyperintense in T2-weighted sequences . Th is picture can be ass ociated with the classical direct or indi rect magnetic resonance (MR) signs of le sion as intraspongiou s contusion of the po sterior portion of the tibial late ral plate and of the corresponding femoral condyle, po sterio r dislocation of the lateral meniscu s, hypercurvature of th e po sterior cruciate lig ament, anter ior tibia l shift, involve ment of the ant ero lateral cap sular ligament, and Segond fracture (a typical avulsion of a cortical bon e fragm ent from the pro ximal tibial epiphys is) (Fig. 4.7) .

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For this reason , MR not only can identify correctly t he site and extent of the ligamentous damage b ut can also offer an accurate assesment of the degree of les ion t hanks to evalu ati o n of the status of the surro un ding structures .

Suggested Readings Azouz M, Oudjha ne K ( 1998) Disorders of the upper extremity in childre n. Magn Reson Imaging Clin N Am 6:677-695 Best T ( 1995) Muscle-tendon injurie s in young athletes. Clin Sport s Med 14:669 -686 Busch M (2000) Sport s Medicine in children and ado lescents . In: Lovell and Winter's Pediatric Orthopaedic s, 5th edition . Lippincott Williams and Wilkins, Philadelphia, pp 1273-1313 Clancy W ( 1990) Tendon tra uma and overuse injuries. In: Leadbetter WB, Buckwalter JA, Gordon JS (eds) Sport s induced inflamma tion : clinica l and basic science conce pt. Park Ridge, AAOS, pp 609-6 18 De Marc hi A, Robba T, Ferrar ese E et al (2005) Lo studio radio logico delle lesioni musco lari: stato dell'arte. Radiol Med 11 0: 11 5-131 Ecklund K (2002) Magnetic Resonance imaging ofpediatric muscu loskeletal trauma. Top Magn Res Imaging 13:203-218 Emery K (2006) Imaging ofsports injuries ofthe upper extremity in children. Clin Sports Med 25:543568 Gill TJ, Lyle JM ( 1996) The immature ath lete. Clin Sports Med 15:401-423 Long G, Coop er JR, Gibbo WW (1999) Magnetic Resona nce imag ing of injuries in the child athlete. Clin Radiol 54:78 1-79 1 Palmer WE, Kuong SJ, Elmadbo u HM ( 1999) MR imaging of myotendi nous strain. AJR Am J Roentgenol 173:703-709 Peetrons P (2002) Ultrasound of musc les. Eur Radio l 12:35-43 Prince JS, Laor T, Bean JA (2005) MR I of anter ior cruciate ligament injurie and associated findings in the pediatric knee: change s with skeletal maturation. AJR Am J Roentgenol 185:756762

Traumatic Lesions of the Peripheral Nerves

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E. Pacciani, F. Ran disi, C. Orazi, 1\1. Valle and C. Marti no ll

5.1

Introduction

Traumatic peripheral nerve lesions are relatively rare in the pediatric age group and are generally distinguished by a more rapid healing process and an improved prognosis compared to les ions obs erved in adults. The type of nerve injury varies according to age. Nerve lesions from sprains and accidental insult during treatment of peripheral nerves, as happens in particular with the sciatic nerve, generally occur during th e neonatal period; lacerations from cuts or compression of a nerve can occur in children over 3 years of age. In pre-adolescence, the most frequ ent causes of nerve lesion are intra-articular dislocation, and fractures of the elbow (especially supracondylar fractures) and knee, which are sometimes a secondary consequence of sports injuries. Supracondylar fractures of the elbow with severe dislocation of the bone fragments can lead to a nerve lesion of the median nerve and the ulna, whil e th e common lesion of the peroneal nerve is most frequently caused by spraining the knee during sports such as football and skiing. Nerve deficits resulting from elbow fractures generally have a positive evolution with a relatively rapid spontaneous recovery. In adolescents, peripheral nerve lesions are similar to those encountered in adults and are mainly caused by road accidents or by wounds from firearms or knives. A simplified classification of nerve lesions proposed by Seddon includes the fol lowing: traumatic nerve root avulsion of the spinal marrow neurotmesis, in which there is complete disruption of the nerve and the nerve sheath axonotmesis where the nerve sheath is intact but the axons are disrupted

E. Pacciani (C8I) Department of Diagnostic Imaging, Pediatric Hospital "Bambino Gesu", Palidoro (RM), Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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neurapraxia , where the damage involves the perineural sheathing while axonal continuity is preserved. Neurotmesic lesions represent the severest degree of nerve lesion, while neurapraxi al lesions correspond to a temporary nerve dysfunction without permanent damage. The clinical diagnosis of a peripheral nerve lesion in the pediatric age group is often difficult, especially in small children , and normally involves the examination of nerve conduction (neurography) and the spontaneous and voluntary activity of muscular regions, which is not always easy to do due to the lack of cooperation from small children. Diagnostic examinations to cre ate images, carried out on completion of electrophysiological studies, are being used increasingly frequently to identify the site of the lesion and to establish the cause and extent of the dam age. Imaging studies , generally used to identify the presence of hematomas in the seat of the lesion, or muscular alterations that are secondary to the nerve damage, can also allow identification of nerve structures and possible lesions of them . Ultrasound and magnetic resonance imaging (MRI) are the main imaging methods capable of meeting these requirements.

5.2 Ultrasound Scanning Th e identification of nerves using ultrasound scanning is based on precise knowledge of their locali zation and the course of the medical problem and on careful analysis of anatomical relationships with surrounding organs. Modern ultrasound scanning equipment with broadband transducers, which have high spatial resolution for the study of superficial structures , is capable of identifying the main nerves that run through the limbs and most of the secondary and terminal ramifications, even when the ir size is less than a millimeter. When evaluated along the long axis with a highfrequency transducer, the internal structure of the peripheral nerves displays an unusual arrangement , made up of a series of elongated hypoechoic areas with a fascicular appearance, which are parallel to each other and separated by hyperechoic bands. Hypoechoic areas are arranged in series and have a well-defined appearance; they are oriented along the longitudinal axis of the nerve. Using transverse scanning, the fascicles take on a rounded appearance and are embedded in a hyperechoic matrix (Fig . 5.1) . Comparison between ultrasound scans obtained in vitro and the corresponding histological sections has demonstrated that the hyperechoic areas correspond to the fascicles , while the hyperechoic matrix is related to the interfascicular epineurium. With entrapment syndromes, traumatic lesions of nerves constitute one of the most important applications of ultrasound in diagnosis of the peripheral nervous system, thanks to the quality of the diagnostic information provided, which has an important effect on the clinical handling of the patient.

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Fig 5.1 Echostructure of the peripheral nerves. a "Short axis" scanning of the ulnar nerve (arrows ) obtained using a 17-5 MHz transducer. b Schematic diagram of the internal structure of a peripheral nerve. In the scanning plane, the structure of the nerve is characterized by a "honeycomblike" appearance, due to the presence of rounded hypoechoic areas (arrowhead) which represent the fascicles

The amputation of a periph eral ner ve usuall y evolves int o a po st-traumati c neuroma. This can be vis ua lize d usin g ult rasound, as an elongate d hypoechoic mass tha t gro ws rel atively rapidly after th e traum a on the edges of the amputated nerve. Ultr asound diagno sis is based on visualization of the connect ion of the neu rom a with th e distal edge of the ner ve. Most of th e neuromas cau sed by amputati on have regula r edges , although in some cases they can have an irregular appearance when th ere are fi brous adhes ions an d ba nd s with th e sur roundi ng tissues. In lesion s cause d by deep traumas of th e periph eral ner ves of limb s, ultrasound has several significant adva ntages over MRI , mai nly in eva luation of the ne rve damage in an acute phase, where th e inte nse edema and hemorrhage of the soft ti ssues along the stab incisi on of the wo und cau se a wides pread inc rease of the sig nal in Tzweight ed seque nces , so that it becom es impossi ble to mak e a preci se identi f ication of the cho rdae and th e lesion s ca use d by them. Oth er sig nifi cant advantages of ultrasound cons ist of th e po ssibil ity of exami ni ng , in a sing le scan, lon g segme nts of nerves in limbs in a few seconds and, in th e presence of a continuous lesion , the ability to orient the tran sducer a long the longitudinal axis of the ner ve concerned, wh ich frequentl y runs obl iquely compared to the orthogonal plane s used in MRI. Thi s ca n prove part icul arly important in preoperat ive ass ess ment in the case of complete ne rve lesion s, wh en it is necessary to obt ain a preci se me asurement of the di stance between th e stumps and the caliber of the ner ve at th e level of the lesion , in order to plan a tran spo sition operation (grafts of se nsi tive nerves) or syntheti c tubul ization. In these cases, high -r esolution ult rasound provid es ex tre me ly acc ur ate resul ts fo r preoperative pl ann ing. In th is regard , it is use ful to rem ember tha t m ea su rem ent of the

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distance betw een th e stum ps mu st include not onl y th e end-to-e nd distanc e of th e n erv e stumps but also, in th e presenc e of termin al n euromas , th e en d-to-en d distanc e of th e neuromas, which must obviously be resected during surge ry (Fig. 5.2). In th is spe cif ic f ield, ultrasound ha s undoubted ad vantag es, mak ing it po ssibl e for th e sur geon to follow th e course of the nerve branch in real tim e an d to fix th e reference points on th e ski n re late d to localizat ion of th e lesion s. After re construct ive surgery, ultrasound allows reliabl e asse ssme nt of th e continu it y of th e ner ve at th e level of anastomos is and exclus ion of a per in eural flu id coll ection. A foc al increa se of th e volume of th e ner ve can be register ed, corresponding to th e suture lin es at th e lev el of both an astomoses. Thi s inc reas e mu st be con sid er ed within th e standard limits when it is relat ively small and fu siform. On th e oth er hand, th e pr es enc e of hyp ertrophic fibrous ti ssu e at th e ana stom osis can suggest inadequate fu sion of th e nerve heads, oft en resulting from ex cess ive tension or supra-i nfe ct ion . In th e autogenous gr aft s, th e interven ing tr act gen er all y corresponds to one or more segm ent s of a sur al nerve donor inserted in parallel to join th e proximal and distal fa scicular structures of th e damaged n erv e. In deep wound s th at cau se partial discontinuity of the fasc icl es without causing a complete int erruption of th e chorda, ult rasound can mak e it po ssibl e to qu ant ify th e perc entage involvement of the fascicles, comparing the number of fa scicl es embedded in the hypoechoic neuroma with re spect to those that maintain a regular mo rphology and are external to it. In other case s, the neuroma m ay affect the entire thickness of the nerve, even though the les ion is not complete, causing a fu siform increase in volume which take s on a globally hypoechoic echostructure with loss of the fas cicu lar appearance (Fig. 5.3) . However, the state of the sing le fascicles (interrupted or con-

Fig.5.2 Complete continuous lesion of the ulnar nerve at the third median of the arm of a 15-yearold girl following a deep wound caused by a glass splinter. The ultrasound image, performed with a 17-5MHz transducer and suitably aligned according to the longitudinal axis of the nerve, demonstrates the proximal stump (open arrows) and distal stump (white arrows) of the nerve, which tcrminate in hypoechoic ovoid areas that correspond to amputation neuromas (N). One can observe the larger size ofthe neuroma in continuity with the proximal stump. For correct pre-surgery mapping, the distance between the stumps must be calculated between the apices ofthe neuromas (dl) and between the junctions between neuromas and the nerve with a normal appearance (d2)

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t inuous) in the context of a ne ur om a that has developed in the pr esen ce of a partial nerve lesion cannot be defined using ultrasound, given the hypo echoic appe ar anc e of th e n er ve tissu e and th e scar t issue that surrounds it. Sp rain/traction lesio ns m ay be of a iat rog en ic nature, res ulti ng from surge ry (for ex ample, elongati on surgery of limbs, po sitioning of ost eo syn th etic devices to stabi lize fractures), or th ey may be se condary lesion s ca used by distortion traumas (p artly du e to th e gre ate r cap sulo-l igam entous laxi ty of artic ulati ons in pedi atric age ) or articular d islocation. If th ese frac tures involve dislo cat ed bon e stum ps , th ey can cause sprai ns of th e chordae, lead ing to a fun cti ona l deficit tha t is propo rtion al to th e exten t of th e sprai n. Th e n erves that are principally subject to sprain lesio n s in chi ldr en are the ra d ial ner ve (in fractures of the hum eral diaphysis) , uln ar nerve (in suprac on dy lar fractures of th e hum erus) (F ig. 5.4), and common f ibular nerv e (in distortion traum as of the knee ). In fractures of th e hum eral diaphysis, wh ere there is an on set of functi on al deficit of th e ra dial ner ve as an eve nt th at is both sy nc hronous with th e tr aum a and subsequ ent to th e re duc ti on surgery, ult ra sound can com pens ate for th e limitat io ns of M RI relat ed to th e inade quate contrast betw een loco-reg ion al soft tissues (du e to an inten se edema an d th e presenc e of granulation tissue th at alt ers th e sign al, mak ing it difficult to identi fy the nerve and qu anti fy the dam age) and the artifa cts ca us ed by osteosynthesis equipment. In thi s cl in ical sc ena rio, in wh ich ele ctrophysiological ex aminat ion s often m ake it impossib le to decide on the be st the rapeutic stra tegy, ult rasound can exclude a lesion-in-continu ity of the ra dial nerve , identify a confli ct

Fig.5ol Partial traumatic lesion of the median nerve in a 12-year-old boy with a cut wound on the volar side of the left wrist. a Longitudinal scan of the median nerve (arrows) obtained using a 12-5 MHz transducer at the level of the carpal tunnel. The median nerve appears to be widely thickened and hypoechoic (arrowheads), corresponding to the plane of lesion (cur ved arrow) in the absence of definite gaps. The flexor tendons of the fingers ttfl, see below) have a normal appearance. In the deepest part ofth e image, it possible to see the bones, still partly cartilaginous, which form the floor of the carpal tunnel; the radius with the secondary nucleus of ossification of the epiphysis (e), the semilunar valve (SL), and the capitate (Ca). h Corresponding clinical picture, highlighting the cutaneous scar (arrows) of the previous cut wound

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Fig 5.4 Neuropathy of the ulnar nerve at the elbow following a supracondylar fracture of the humerus with significant dislocation of the bone stumps. a X-ray examination of the elbow performed in anteroposterior projection. b "Short axis" echotomographic scan of the ulnar nerve (arrowheads), examined on the pathological side on a slightly cranial plane with respect to the cubital tunnel, highlights its marked increase in volume with respect to the contralateral nerve (c) as the outcome of the traction induced by a supracondylar fracture

betwe en th e ner ve and fra cture fragm ents, and differ ent iat e an entra pme nt by scar tissue fro m a sim ple spr ain le sion of th e n erv e, giving indi ca tions as to wh ether or not to revise th e surgi cal strategy. One of th e lesion s cau sed by nerve sprai n wh ich is commonly found in pediatric age involve s th e comm on fibular nerve in th e hamstring (F ig 5.5) . Th is nerve, which is "anchored " in its seat, between the bifurcation of th e sciati c ne rve and peroneal tunn el , is particularly susce pti ble to sprain traumas in the region of the kn ee due to di stortion s or po sit ion s that involve prolonged stre tching . Th e result is a function al deficit of var ying m agnitude in th e inn er vat ion terr itory, and demonstrat ion of an ex te nsi ve fu siform neuroma of the nerve in th e ham string, ext ended by bifurcation until it reaches distally a plan e passing betw een th e lateral gemellus and th e tendon of the biceps femo ri s tendon jerk reflex . More seri ous tr aumas, such as dislocation of the femor al -tibial junction with avu lsion of the bic ipita l groove, can le ad to lace ration of the fi b ula r ne rve . Fortunately, these tr aumas ar e ex ceptional in pediatric age .

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Fig.5.5 Neuropathy of the common fibular nerve in a patient with previous serious distractive tra uma of the knee . a Echotomographic examination of the hamstring, performed with a 12-5 MHz transducer of knee, highlights the widespread fusiform increase in volume of the commo n fibular nerve (arrows), which is fully hypoechoi c with loss of the fascicula r str ucture, with respect to the normal nerve of the contralateral limb (b). c MRI image, obtained with T i-weighted spin echo sequences, confirms the widespread increase in volume of the fibul ar nerve of the hamstring, in its co urse between the lateral gemellus (gl) and the bicep s femoris tendon je rk reflex tbf) . d Surgery confirms the conspicuous increase in volume of the fibul ar nerve (arrow), which is probably comp atible with a sprain trauma of the fibe rs

5.3 Magnetic Resonance Imaging In th e case o f a periphe ral nerve le sion caus ed by traum a, M R I is often u sed to identi fy the presence of po ssible hematoma s (F ig. 5 .6) o r hemarthro sis res p o ns ib le fo r n erve compre ssion : in this ev en t, the neuropathy ge n era lly presents a complete regre ssion , w ith res o luti o n of the cause of c o m pressi o n . M R I is abl e to d emon strate signal modif ications ca used by a ner ve les ion an d prov id es inform ati o n about the durat ion o f the les ion. In no rmal co nditi o ns th e muscl es pre sent an inte rme di ate signal in T i-wc ightc d sequences a nd a low intensi ty o f

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Fig.S.6 Neuropathy of the femoral nervecaused by a hematoma in a 12-year-old patient with avulsion of the anterior superior iliac spine. T i-weighted turbo spin echo axial MRI. performed with suppression of the adipose signal after administration of contrast agents, reveals the presence of a hematic cyst (arrows) lying between the iliac wing and the iliopsoas muscle. The cyst indirectly causes compression of the femoral nerve whichstarts in the muscular plasterapplied between the ileumand the psoas

signa l in Tj-weighted sequences . Chroni c mu scul ar denervation is characterized , in T j-we ighted sequences, by atrophy and adipose infi ltration of the mu scle ( Fig. 5.7a). In the cas e of suba cute lesion s, the denervated mu scle s do not displ ay significant modificat ion s of the signa l in T j-we ighted image s, while they displ ay an attenuated signa l in Tj-weighted sequences with saturation of the fat in rela tion to the edema (Fig. 5.7b) . Identification of the mu scle s involved in the denervation process can provide useful indications for identifying the per ipheral nerve that is affected and that therefore requires examination. In no rm al condition s, the peripheral nerves di spl ay a low intens ity of signal, in both T 1- and T2-weighted sequences, and are frequently surr ounded by adipose tissue a long the ir course ; thi s anatomica l ch aracteristic make s identification easier, in the T j-we ighted sequences as hypointens e form ations, with a typical fascicular structure, bounded by a high level of hyperintensity of the per ineural fat (Fig . 5.8). In the case of an acute ne rve lesion , the peripheral le sion s typically pre sent an increase in both caliber and intensity of signal in T 1- and T2-weighted sequences , with an extension that varies prox imally with the pre sence of an intraneura l edema and with Wallerian degenerat ion (Fig . 5.9) . In ch ronic lesions, however, usually only an increas e in th ickness of the nerve can be recognized (Fig. 5. 10). Loc ali zed thickening of the nerve ca n also be corr ela ted with the pre sence of an amputation neu roma or per ineural scar tissue . The se circumstances are di ff icult to di stingui sh even after administration of param agnetic contras t agents . The amputation neuroma is supported by a non-neop lastic reactive proliferation in th e seat of the nerve lesion (Fig. 5.11). The use of paramagn etic contrast agents also mak es it possible to recognize th e presenc e of scar tissue in the perin eural sea t respon sibl e for the neuropath y (Fig. 5.12).

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Fig 5.7 Chronic muscle denervation of the leg ca used by lesion of the common fibular nerve (a) and the subacu te nerve of the deltoid musc le caus ed by lesion of the axillary nerve (b) in two different patients, who are 15 and 16 years old respectively. a The T r-weigh ted turb o spin echo axia l MR I image displays extensive atrophy and adipos e infiltration of the mu scles of the anterior and anterior lateral cavities of the leg. b The T2-weighted spin echo cor onal MRI image with suppres sion of the adipose signal shows a widespread intensity of the deltoid muscle

Fig.5.ST i-weighted spin echo coronal MRI image of the right brachial plexus in a IO-year-old patient shows the cho rdae (black arrows) with a typical fascicular appeara nce, which are parallel to the co urse of the subclavian vesse ls (white arrows ). The T i-weightcd sequence also highlights the perineural adipose tissue and the relationships between the nerve structures and the subclavian muscles (sm) and the sma ll pectoral muscle (spm)

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Fig.S.9 Neuropathy of the radial muscle following a supracondylar fracture of the elbow in a 6-yearold patient. Tr-weighted turbo spin echo axial MRI images (a) and Ts-weighted turbo spin echo axial MRI images with suppression of the adipose signal (b) display an increase in volume and intensity of the signal of the radial nerve (arrow)

Fig.S.10 Neuropathy of the right sciatic nerve in a 4-year-old patient suffering from recur rent dislocation of the right hip. Tz-weighted spin echo axial MRI shows a moderate increase in volume of the right sciatic nerve (arrowhead) : there is also an alteration of the signal of the musculus quadratus of the right femur

More recently, evolution of MRI techniques has m ade it po ssib le to use a new method for studyi ng the peripheral nerve sys tem, ind ica ted using the term MRI neurog rap hy . Thi s technique m akes it po ssible to sh ow peripheral nerve s in a simi lar way to ang iograph ic im ages, with improved di fferenti ation of the nerve stru ctures of the muscles . The use o f MRI neurography in pediatric patients is particul arly interesting given th eir intol erance to needle e le ctromy og raphy. MRI neurography invol ves th e use of m agn et s with a high magnetic f ield (from 1.5 Tesla) and th e us e of sur face coils. Th e mo st wid el y used technique is based on th e use of Tz-w eighted sequences with sup pre ssi on of th e ad ipose s ig nal. Thin contiguous scanne rs are g en erally used

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Fig.S.11 Amputation neuroma of the median nerve caused by a cut lesion in a 13-year-old patient. a In the saggital spin eeho T i-weighted image, one can observe marked thickening of the median nerve (arrow), which displays a normal caliber proximal to the neuroma (arrowhead). b The Tl weighted spin echo axial MRI image with suppression ofthe adipose signal using admin istration of paramagnetic contrast agents shows intense potentiation of the amputation neuroma (arrows)

Fig.S.12 Neuropathy of the ulnar nerve in a 5-year-old patient with a previous supracondylar fracture of the elbow. Ti -weight ed turbo spin echo axial MRI images taken before (a) and after (b) administration ofparamagnetic contrast agents. The ulnar nerve (arrow) has increased in volume and is bounded by a thin hyperintense annulet after the admini stration of contrast agents (arrowhead) , which can be ascribed to perineural scar tissue (surgically confirmed)

and ar e or iented a long the m a in course of the nerve structures requiring ex aminat ion. Exam ination performed using thi s technique all ow s only parti al representation of the ne rves in sing le sca ns; subsequently, reformatting of the im age s using Multipl an ar Recon struction (MPR) or Max imum Intensity Projection (MIP), using coronal or ob lique planes, allows compl ete id entificat ion of the nerve structures und er exami nation . In peripheral nerve lesions, MRI neurography, performed a ft er completion of conventional MRI , is capabl e of provid ing a more pr ec is e a sse ssment of neural

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damage, making it possible to identify any possible breaks in the nerve structures. MR[ neurography is extremely us eful for studying traumatic lesions of the brachial plexus (Figs. 5.[3 and 5.[4). Brachial plexus injures du e to accidental trauma in children are relatively rare compared to obstetric lesions. Recently, Smith and colleagues have described the use of MR[ neurography in childbirth lesions of the brachial plexus.

Fig.S.H Lesion caused by wrenching of the right brachial plexus in a 16-year-old patient. MRI neurography using oblique-coronal planes reveals the presence of a nerve avulsion (arrowhead) and trauma-induced meningocele of the C7 root (arrow)

Fig. S.14 Neuropathy of the radial muscle in a simple supracondylar fracture of the elbow. a The X-ray shows a marked dislocation of the bone fragments. b MRI neurography using sagittal planes highlights an entrapment of the radial nerve (arrows) between fracture stumps. c In axial MRI in protonic density it is possible to identify an increase in the volume of the radial nerve between the fracture stumps (arrow)

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In the event of nerve lesions in pediatric age, the diagnostic approach using imaging is certain to involve the preliminary use of an ultrasound examination capable of defining, on the basis of the clinical and electrophysiological measurements, the site and extent of the lesion. MRI, performed in pediatric age generally involves sedation of the young patient, and will be used as a diagnostic technique exclusively in selected cases where ultrasound is not decisive. In n erve lesions of the limbs, the use of immobilization devices, such as thoraco-brachial plaster or air cushions, can allow MRI examination without resorting to sedation, wh ich will have to be used if th e aforementioned technique fails.

Suggested Readings Bacigalupo L, Bianchi S, Valle M, Martinoli C (2003) Ultrasonography of peripheral nerves. Radiologe 43:84 1-849 Carmel P (1982) Peripheral nerve lesions in pediatrics age group. Pediatr Neurosurg, New York, Grune & Stratton , pp 345-360 Filler AG, Maravilla KR, Tsuruda JS (2004) MR neurography and muscle MR imaging for image diagnosis of disorders affecting the peripheral nerves and musculature. Neurol Clin 22:643682 Fleckenstein JL, Watumull D, Conner R et al (1993) Denervated human skeletal muscle: MR imaging evaluation . Radiology 187:213-218 Howe FA, FillerAG, Bell BA et al (1992) Magnetic resonance neurography. Magn Reson Med 28:32838 Kline D, Hudson A (1995) Nerve Injuries. WB Saunders, Philadelphia Koltzenburg M, Bendszus M (2004) Imaging of periphereal nerve lesions . Curr Opin Neurol 17:621-626 Seddon H (1975) Surgical disorders of periphereal nerves, 2nd edition . Churchill Livingstone, Edinburgh-London Silvestri E, Martinoli C, Derchi LE et al (1995) Echotexture ofperipheral nerves : correlation of US with histologic findings and criteria for differentiation with tendons . Radiology 197:29 1-296 Smith AB, Gupta N, Strober J, Chin C (2008) Magnetic resonance neurography in children with birthrelated brachial plexus injury. Pediatr Radiol 38(2): 159-163 Weig SG, Waite RJ, McAvoy K (2000) MRI in unexplained mononeuropathy. Pediatr Neurol 22: 314-317

Imaging of Regional Injuries: The Axial Skeleton - the Skull, Vertebral Column, and Thoracic Cage C. Fonda. 1\ 1. l\lortilla. C. Ces arini and 1\1. Basi le

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The Skull In contrast to head inj ur ies in adults, th ere are thr ee distinct causes of skull and brain trauma in childr en: birth trauma, acci denta l trauma, and non-accident al trauma. Acci dental trauma includes impact injuries in children and adol escents. Static for ces slowly appli ed to the head can produce skull frac tures, contusi ons, and lac erations. Falls from low height s can cause linear fractures (2- 3% ) and are rarely acc ompanie d by intracranial lesion s. Mor e serious consequences are th e res ult of high-energ yimpa ct injur ies, which oft en involve multipl e trauma whereby severe skull and brain injuries form a part of the clinical present ation (19 %), oft en pro ving fatal or cau sing severe disabilit y.

6.1.1

Epidemiology Skull fractures are found in around 27% of ch ildren with he ad inju ries - in around 75% of major traum a pat ient s and 10% of minor traum a patients. The incidence reported in the literature is highl y var iable: some studies report only 2% of fractures in minor head inj uries. Most fractures are linear and involve the pariet al bones, with the pre sence of hem atoma overl ying the fra cture (Fig . 6.1) . These fractures spontaneously he al. The pre sen ce of a fracture cannot be ruled out by a negative rad iolog ical exam ination, and the simple visua liza tion of a fracture line says little in relation to the possible

C. Fonda (12=<:1) Department of Pediatric Radiology, Children's Hospital Meyer, Florence, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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Fig. 6.1 Three-year-old child. Accidental trauma. a Lateral view radiography. Right parietal thin horizontal fracture line (arrow). b CT with multiplanar coronal reconstruction and bone window. Swelling of the epicranial soft tissue and the underlying thin parietal fracture line can be identified (arrow)

Fig. 6.2Three-year-old child. Accidental trauma from a fall. a CT 3D rendering of the skull shows left parietal fracture line (arrows). b Axial scan with parenchymal window shows the small layer of epidural hematoma below the fracture line and swelling of the epicranial soft tissue (arrow). c Axial scan with bone window: left parietal fracture line can be identified, easily distinguishable from the hypoattenuation of the coronal and longitudinal sutures (arrow) a lte rat ion of th e intracrani al structures , an d in itse lf do es not modify tr eatment. Onl y 40% of ch ildren with epidur al hem atom a, and onl y 15% of those with subdural hematoma, ha ve a fr acture (Fig. 6.2). In ch ildre n, a pathologi cal clinical pr ese nta ti on with no sign of fracture but which non ethel ess requi res tr eatm ent, including ex tra-ax ial hem atom a, is not a rare eve nt. With computeri zed tomography (CT) vo lume tri c acq uis itions, it ha s become harder to miss even th in fracture lines, as occurred in ax ia l secti ons when the fracture line was par allel to the sca n pl ane . Demonst ration of the traumatic le sion in itself becomes importa nt in non-accident al injuries, even in the abs ence of bra in injurie s.

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Fig.6.3 Radiograph of a right parietal "ping-pong fracture". The depression of the skull is clearly evident, similar in appearance to a squashed ping pong ball

Fig. 6.4 CT of a right parietal depression fracture radiating superiorly (arrows). a 3D reconstruction. b Axial scan with bone window

Th e mo st common fractures are lin ear parietal fractures, which can be hori zontal or vertical. Short vertical fractures can be diff icult to di stinguish fro m accessory sutures. Th e f ind ing of a fracture may be fa ci lita ted by evide nce of swell ing of the overl ying epicran ial soft t issu e (Fig. 6. 1b) . Occipital or frontal fractures are more commonly ca use d by a direct blow . Th e swell ing of epicranial soft tissue in the area of th e blow can be associ at ed with leakag e of ce rebros pinal flu id th rough the fracture (th is occurs at the point of max imum deform ation of the skull as a result of the ene rgy of the blow) . The plast icity of the infant sk ull is such that de form at ion s ca n occur, g iv ing rise to depress ion s known as " ping pong fractures" (Figs. 6.3 and 6.4) . Growing skull fracture s, al so known as cranioc erebral ero sion s (F ig . 6.5) , are rare sequela e of skull

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Fig.6.S CT of seven-year-old child with "growing skull fracture". Lytic area in right posterior parietal location. a Coronal multiplanar reconstruction (MPR) with parenchyma window. h 3D volume rendering. In correspondence with the lytic lesion, involvement of the cerebral parenchyma can be seen through the foramen created by the fracture and in the presence of a dural tear. The parenchymal pressure causes progressive widening of the lytic area, hence the name "growing skull fracture"

fractures, where a skull defect progressively enl arge s following a tear in the dura mate r, as can occur for example in firearm inj uries in war zones . These injuries are ch aracterized by a soft, palp able swelling th at may be cystic , in the context of an osseous defect of the skull. In the absenc e of a dur al tear there will be no po st-t raumat ic deficit of the skull, although cases have been de scribed with the dur a int act. A fracture ass oc iated with hemorrhag ic contusi on of the unde rlying br ain, if accompanied by a dural te ar, can give rise to a growing skull fracture. Afte r having reached the ir max imum extent, the se fractu res stop growing and rem ain sta ble until ado lescence . A fra cture with diastasis greate r th an 4 mm can be con sidered at risk of developing into a growing skull fracture . The mo st common site for the se frac tures is the parietal reg ion . In the pre sence of an extensive and comminuted fra cture, the re may be parti al reabs orption of the bone fragments, leaving a lar ge gap in the skull with irregul ar margins and scattered fra gments in the dur a. Sku ll fractu re s ca n be ass oc iated with various int ra- and ext ra-axi al intr acr ani al lesion s. Th ese include foci of in tra pare nchyma l laceration s/contusion s, extra dura l hem atomas (Fig. 6.5), acut e subdura l hematomas ( Fig . 6.6) , m ixed subdura l hematomas, paratentorial hematomas, subarac hno id hemorrhages, and diffu se axonal injury. Th e clinical presentation can be complicate d by the presenc e of intracran ial involve men t syndromes , or vasc ular lesion s or frac tures to th e skull base, with po ssible cereb ro spinal flu id leak age. Ce rebral contusion s occur at the site of impac t and on th e opp osite side of the skull as a result of th e contrecoup effec t cause d by deceleration of the brain parench yma within the skull. They are characterized by hyperatte nuating foci at CT, indic ating th e presence of punctate hemorrhages. In th e hyperacute ph ases of the se foca l a ltera tions , the y may be visualiz ed at magnetic resonance (MR) as areas of marked parenchymal hype rintensit y in ima ges obt ained with T2*weighted gradient-echo (G E) acquis itions . Diffu se parenchymal edema is ass ocia ted, often alongsi de the fracture site.

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Fig.6.6 CT in five-year-old child. Road accident trauma. a, b Axial scans with parenchyma window. Extensive and prevalently hyperattenuating layer with biconvex shape indicative of hyperacute epidural hematoma with left parietal-temporal location. The fracture line is visible in correspondence with the middle meningeal artery, the rupture of which is responsible for the abundant hematoma (arrows)

Epidural hematoma is charac terized by its biconvex sha pe, is extra-ax ial, and app ear s prevalentl y hyperatt enu ating at CT in pro ximity to th e impac t site ( Fig. 6.6). It do es not ex tend beyond the sutures, unl ess a fracture is present. In 90% of cases it arises from ar terial rupture (most commonly the bran ch es of th e middl e men ing eal art ery) in proximity to th e frac ture; more rarely, th e origin is venous (10 %) du e to fra ctures in prox im ity to the venous sinuses . It can reach signifi cant d imen sion s and con stitutes a rea l emerge ncy in pediat ric pat ient s. Wh en its extens ion and depth are lim ited, a con servat ive approach can be adopted . Acute subdura l hematoma appears as a crescent-s hape d extra-ax ial collec tion in th e subdura l space (Fig . 6.6), extendi ng over the cerebral con vexit y. It can cro ss the sutures in re lation to its exte ns ion betw een th e arachnoid and th e interna l layer s of th e dur a mat er, and extend along the falx cerebri ( Fig. 6.7) and th e tentorium , in correspondenc e with the middl e, ante rior, and po sterio r crani al fossae. The hyp eracut e form (wi thin 6 hours from the trauma) can be visualized at CT as a mixed and inhomog enous hyperatt enu ation , or app ear hypoattenuating ; afte r 6 hours, some 60% of subdural hematomas app ear hyp eratt enu ating ( Fig. 6.8). ln th e con text of clotting disord ers or mark ed ane mia, hypo att enu ation may per sist. At MR the hyp eracut e hem atoma tend s to appear hyperint ense in T i-wcig htcd images to th en becom e progr essively mildl y hypo int en se. In T2-weighted images in th e hyp era cut e phase, it tend s to appe ar hyp er inten se and progress tow ard s hypo int ensit y. A head injury can be accompanie d by the presence of po st-traumatic suba rac hnoid hemorrhage , due to the pre sence of blood in the cortica l sulci and cisterns. [f it accompanies other br ain injuries, the prognosis is un favor able . lt can become compli cated with vasospasm , [ate infarction, and hydrocephalu s. At CT it appears as a hype rattenuating area within the cistern s prevalentl y in prox imity to the brain contusion

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Fig. 6.7 CT in an eight-year-old child. Serious road accident. a 3D volume rendering, and b axial scan with parenchyma window. Left parietal-occipital comminuted compound fracture extending inferiorly in the retromastoid area. Extensive hyperattenuating laceration-contu sion in left parietal location associated with abundant hypoattenuati ng perilesional edema and extensive interhemispheric subdural hematoma (arrows)

Fig. 6.8 Trauma from a non-accidental fall in a 26-day old infant. a Axial scan with parenchyma window; right fronto-parietal depression fracture (ar row) appearing more marked at the apex with associated hyperattenuating subdural hematoma and subgaleal hematoma . b 3D volume-rendering reconstruction. The broad fracture rim originating from the anterio r fontanelle can be identified

or sub dura l hematoma ; at MR it appears with signa l hyperintensity in FLAIR seq uences, which ar e the mo st sens itive in MR but le ss speci f ic th an C T. Head inj ur ies can al so ca use m echanical inju ry to th e bra in paren ch ym a known as diffu se axon al inj ury (O AI) . Th e fo cal damage is th e result o f a vi ole nt sw irl ing motion o f the cereb ra l co rtex wi th resp ect to th e d eep br ain structures. This cause s a stre tching of th e ax ons and th e vesse ls acco m panyi ng th em . Pun ctate hemorrhage s

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are thus form ed at the level of th e corticom edullar y j unction (67%) , the corpus callosum (20 %), the deep gray matt er, and th e mesencephalic structures . MR is the diagnostic ima ging modalit y of cho ice as it enables, in T2*-weighted G E images that are sensi tive to magnetic sus ce pti bi lity, amplif ication of the hypo intens ity of the microhemorrhages so they thus become easi ly identifi able thanks to the presenc e of hemo siderin depo sit s. DAI should be suspec ted in those cases of traum a when th ere is a discrepanc y betw een th e neurological presentation and th e neuroradiological imagmg.

6.1.2

Orbital and Nasoethmoid Fractures The orbital cavities and the nasoethmoid compone nts con stitut e important funct ional and aesth etic units of the face . Th e se verity of th e fractures can vary from minor fractur es to complex fractures involving the orb ital-zygomatico-malar complexes . CT is th e preferr ed examination for th e evaluati on of these frac tur es. Zy gomatico-ma xi lla ry fractures are uncommon in children, du e to the lack of pn eum atizat ion in the paranasal sinus es, the el asticity of the bone, and the protective effect of the higher crani al to facial skeleton siz e. Fractures of the orb ito- zygomati co-malar complexes in young children are frequently ass ociated with he ad injuries (Fig . 6.9); comminuted fract ures are uncommon.

Fig. 6.9 Fracture of the maxilla, the orbital floor, and the left zygomatic arch. a Axial CT, and h coronal MPR. The presence of blood-filled sinus and radio-opaque shadow over the nasal passages and the inferior orbital extraconal space can be identified (arrows)

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Orbital rim fractures are rare . When struc k abou t th e supra orbita l rim , the pressure is transferred to th e orbital roof, which can fractur e. In chi ldre n age d less than 7 years, fractur e of the orb ital roof is much more common. This is usuall y the resul t of a direct impact to th e eye and is known as blow-out. Much mo re uncommon are mul tipl e blow-in orbital fractures . With growth, th e frontal sinus becom es pneum atized and extends to the supraorb ital rim, thu s prevent ing direct tran smission of th e for ce of a blow to th e orbital roof (with a reduction in th e frequency of its frac ture) . As a res ult, fractures of the fronta l sinus prevail. Fractures of the orbital roof are cons idere d skull fractures . In general, they do no t require treatm ent , unl ess there is an extensive breach in th e bon e. Fractures of the orbital floor are mor e uncommon than tho se of the orb ital roof: the inci dence of these fractures parall els faci al development. Onl y child ren abo ve the age of 8 years have suff iciently develop ed paranasal sinuses to allow fracture of the orb ital floor and the parana sal sinuses . These fractures are the result of a direct blow to the inferior orbital rim: a dep ression of th e orbit al soft tissue is ge nerated toward s the maxillar y si nus, and the rectal and inferi or oblique mu scle may remai n entra pped in th e fracture line, causing ocul ar hypomotil ity (Fi g. 6.10) . Fracture of th e med ial wall of the orbit is the result of a direct blow to the orbi t. In younger children, it is a fracture result ing from the earl ier development of the ethmoid sinuses . Sub cut aneous emphysem a and intra orbita l air are often pre sent (Fig . 6.11) . The need for surgica l repair of orbital roo f fracture s is rar e, whe reas the need for rep air in orb ital floo r fractures is much mo re common . The vari ety of orbital fractures is best unde rstood with an ana lysis of the site, direction, and force of the blow.

Fig.6.10 l3-year-old girl. Direct coronal

CT. Fracture of the left orbital floor. Entrapment of the inferior rectus muscle in the fracture rim, accompanied by fat tissue dehiscence corresponding with the underlying maxillary sinus (arrow)

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Fig.6.11 Fronto-facial trauma in a child. a Coronal MIP and b axial section with bone window. Fronto-nasal and right ethmoid fracture with extension to the medial orbital walls. The fracture line extends to the right zygoma (arrowheads). Air and blood in the orbit and blood in the ethmoidmaxillary sinus are associated.

6.1.3

Maxillofacial Fractures Max illofacial fractures are less common in ch ildren than they are in adults . Treatme nt need s to take ske letal growth into ac count, to avoid deformit ies with compromised fun ct ion and app earanc e. In 42-55% of ca ses, ther e are ass ociated skull fra ctures, and in 15-24%, there are fractures of th e extre m ities (Tabl e 6.1). Th ese fractures are mo st commonly pro cured from fall s (30-43%), dur ing play and sport (22-23 %), and from car acc id ent s. Facial fractures in pedi atric pati ents acc ount fo r 5% of all craniofacial traumas, with mu ch lower frequ enc ies for children below the age of 5 years . Th e factors responsibl e for th e d iffer enc e with res pec t to th e adult population include th e mu ch high er cran iofac ial rati o, the great er elas ticity of infant bon es, the great er thickness of the soft tissu e which produces a shie ldin g effec t, and th e reduce d or abse nt pneumatizat ion of the und erd evelop ed par an asal sin uses. Th e mo st common fractures ar e nasal fra ctures (60%) , mandibul ar fractures (21 %), and maxill ar y fractures (6% ), wi th ass ocia ted al veol ar fractures. Th e mo st common frac tures requiri ng ho spital ization are tho se involvi ng th e mandibl e, pa rt icul arl y th e mandibular condy les (Fig. 6.12) . Fractures of th e med ial maxillofac ial stru ctures are rare, si nce these fractures require a high-energy impac t. Possible cau se s include majo r road acci dents or ch ild abuse. Th e pres enc e of tooth bud s in the mandibl e mak es the bon e mo re res istant to frac ture . A blow with the same force causes less- sign ificant lesions in a child than it do es in an adul t.

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Table 6.1 Pediatric fac ial trauma I.

Incid cn ce

Less frcqucnt in children than in adults 5-10% of facial fractures in children asal and mandibular fractures arc thc most common Falls. road acciden ts, sport. anima l attac ks. child abuse hili of thc fractures from superior to inferior with increasi ng agc 2. Differ en ces with respect I n adult s hortcr timc availab le in thc manageme nt of an emergency Facial hypodcvclopmcnt lixed stage of dentition Rapid healing ommon association with intracranial and spinal injuries urgical treatment a potentia l cause of deformity 3.

A na to my

raniofacial disproportion in favour of the former, olTering a protective clTect Broad interpu pillary distance and n at na .al dorsum Greater amount of fibroadiposc tissue Development of paranasal sinuses not yet prese nt tability facili tated by high tooth-to-bone ratio Pediatric facial bone with thin cortex

Fig. 6.12 a 3D volume rendering of a fracture with disarticulation of the left mandible (arrow). b Coronal MPR of a bilateral fracture of the mandibular condyles with dislocation of the fractured fragments and on the right fracture of the articular cavity (arrows)

Around 80% of the growth of the m ax illofaci al stru ctur es occurs in the first 2 yea rs of life , and the pro ce ss is almos t com plete at aro und 7 ye ars of age, a lthoug h it continues into the twent ies, w ith a cr aniofac ial rat io at birth of 8: I tha t at complete maturation becomes 0.5: I , The skull act s as a k ind of shi eld for the faci al bones.

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Chi ldre n tend to be mo re pron e to upp er-facial frac tures than lower-facial frac tures , which are more typical in adults . In add it ion, orbital and skull fractures tend to be more common. As the parana sal sinuses develop , lower maxillofaci al fractures becom e more fre quent. Th e usc of CT has becom e commonpl ace in both adults and chi ldren . In the past it was commonplace to perfo rm axial sca ns, and, where possibl e, coronal scans. With th e advent of mul tislice CT and volumetri c acquisit ion s with isotropic resolution, tog eth er with multi planar reconstruction s and the possibil ity of volumetric rec onstruc tions, a detail ed ana lysis of th e bony stru ctures , the cranio facial soft ti ssue, and th e cerebral parenchyma is now possibl e, all the while abiding by the ALARA ("as low as reasona bly achie vable" ) principl e of minimum radia tion exposure . For fractur es of the nasal bon es, plain film radiography in the app ropriat e lateral and axial vie ws is suff icient, as it is for the evaluation of dent al and mandibul ar fractures . Recentl y, the sys tema tic use of ult rasound in the evaluation of na sal fractures was proposed. Orthopantomography offers an adequate evaluation of th e alveolar and dent al struc ture s and is oft en enough for th e evaluation of mand ibul ar int egrit y. For evaluation of the mandibular cond yles, th e orb its, and th e petrous part of the temporal bon e, multisliee CT app ears to be the first-cho ice imag ing modality. Nasa l fractures in pedi atric patients di ffer from tho se in adults due to the prevalent cartilaginou s component and the reduced prominence of the facial profile . These elements expl ain the reduced presence of nasal fractures in children , in whom the prevalent lesion tend s to be diffuse facial edem a. If a fracture does occur, it gene rally involves the nasal septum, which can be fra ctured longitudinally in its anteri or portion , or di slo cated - a common finding in neonatal fractures.

6.1.4 Mandibular Fractures Isol ated dental or alveolar fractures arc common in child ren: the can ines or inc isor s are frequently avul sed due to their ant erior location . These fractures are cons idere d a dental emergency. Dec iduou s teeth do not need to be reimp lant ed, whereas permanent teeth mu st be rei mplante d, at best within an hou r. Mandibular frac tures in chi ldren arc oft en solita ry, unli ke in adu lts whe re they arc oft en multiple. Th e condy les arc commonly th e site of mand ibul ar fractures in children, given the ample medull ary core sur rounded by a thin cortica l rim. Condy lar fractures account for around 3 I% of mandibular frac tures, and midline frac tures of th e face around 17%, usuall y in old er chi ldre n. After the clini cal examina tion, radiological diagnosis is always requ ired and, based on standard radiogr aphy, pano ram ic radiography and CT. Th ere arc thr ee types of condy lar fractu res: int racap sul ar with fracture of the condylar he ad high condyl ar fractures, located at the mandibular neck above the sigmoid notch inferior subcondyla r fra ctures, ass ocia ted with gre en stic k fractures.

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Fractur es of the first type are tho se that mor e read ily produce growth deform ities. Mand ibul ar symphysea l and parasymph yseal fractures are not uncommon, with the ris k of lesion s to the tooth buds. These frac tures are most frequently encountered in orthop edic or head injur ies. Fractures of the bod y and angl e of mand ible tend to be incomplete in children.

6.1 .5

Zygomatic and Maxillary Fractures Zygomatic fractures are generall y caused by a direct blow to the chee kbone . Pneum atizat ion of the maxillary sinus is require d to allow dislocation of the bone, which explai ns why these fractures are uncommon in children. Zygoma tic fractur es are ass ociated with conj unctival hemorrhage, swelli ng of the soft tissues, depression of the pro file of the cheek, and osseou s asy mmetry at palpation of the orbital rim. The fracture is best visualize d with a submenta l vertex rad iograph or with CT. Le Fort fractures are characterized by mob ility of the maxilla with res pect to the skull base, and they present different symptoms and different degrees of severi ty. They all have a high-energy impact in common. The re are three type s: Le Fort I fra ctures: these are the result of a blow to the inferior segment of the maxill a. The fracture line extends horizont ally acr oss the maxillary sinuses. Orbital or nasal fractu res are not pre sent. The pte rygoid plate and the vomer are fractured in the ir lower port ion . Le Fort II fra ctures : more extensive frac tures result ing from a violent impact to the maxilla and nasal bones in a downw ard direct ion . The fracture run s inferiorly and later ally along the medi al wall and the floo r of the orbit, and continues along the later al wall s of the maxill ary sinuses. The pte rygoid plate is fractured at its middle third. Le Fort III fractures : the se correspond to a complete disassociation as a con sequence of a high-energy blow to the nasal bone s. The fracture run s across the nasal bones, the late ral wall s of the orbit , and the zygomatic arch. The nasal septum and the pte rygoid plate are fractured superi orly. The fracture may extend to the skull base.

6.2 The Vertebral Column 6.2 .1

Epidemiology Spinal trauma in pedi atr ic pati ent s can have catas trophic con sequ ences. Childre n have di fferent injury profil es to adults because of their different anatom y and physiolog y and exposure to different risk factors. Vert ebral and spinal cord injuri es are

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relatively uncommon in ped iatri c patients. This is due to the greater mobility and elasticity of the spine during growth, and the lower bod y mass of children, incomplete ossification , and gre ater compressibility of the bone with respect to adults. In In England, the frequency of spinal trauma, whether or not it is accompanied by vertebral disloc ation , without spinal cord injur y, is reported as 2.7-3% of all cases of ped iatri c trauma. Trauma associated with spina l cord inju ry instead accounts for 16-20% of all cases of spina l trauma, with a frequency of 0.6% of all pedi atric trauma cases. Spinal cord injur y without radiologica l abnormalit y (SCIWOR A) occurs in 0.1-0.2% of all pedi atric traum a patient s and in 4.5-6% of all ped iatric spinal trauma patients, with a greater incidence in children below the age of 8 years. Multiple trauma and thoracic traum a incr ease the ris k of both vertebral lesions and spinal cord injur y. Road trauma accounts for 50% of spinal traum a in childr en, followed by fall s from a height. Skull fractures are the most commonly associated lesion s. Road accidents constitute the mo st frequent cau se of spinal trauma , part icularly in infant s. Falls arc more frequent between 2 and 9 years of age, whereas sports-related trauma is more frequently associated with the I0-14-year age group . Head injur ies are associated in 37% of cases. The most frequently involved tract is the cervical spine (36-40%), follo wed by the thoracic spine (34 %), and lumbar spine (29 %). Mult ipl e contig uous lesion s occur in 34% of cases, and non-con tiguou s lesion s in 7% of cases . Younger childr en mor e frequently present a lesion of the superior cervic al spine. The apex of the cer vical curve in flex ion is located at a different level in children (C2-C3) than in adult s (C4- C6). Isolat ed disc lesions, radicular lesions of the caud a equina, or frac tures of the tra nsverse or spinous processes without further associations occur in 28.7% of cases. Thor acic lesion s are pre sent in 11.4% of patients with spina l traum a.

6.2.2 Radiological Examination Radiography of the spine maint ains its usefulness as a fir st-choice modalit y in the evaluation of spinal trauma, especi ally in the cervic al spine. The guidelines of the American Association of Neurologica l Surgeon s, however, state that radiological examin ation may not be necessary in children who are awake, able to speak, with no neu rologi cal deficit or muscul ar stiffness in the neck , and no pain resulting from the trauma , and who show no signs of intoxication . The application of the NEXUS study criteri a (Nation al Emergency X-ray Util ization Stud y) has reduced the need for imaging of the spine in 20% of the pedi atric popul ation . The lateral view is esse ntial in evaluating spinal trauma and alone has a sensit ivity of 79%. In traum a of the cerv ical spine, the th icken ing of the paravertebral soft tissue has a low predictive value in ped iatric patient s. The role of flexion and extension maneuvers is curr ently still controversial, and their application seems to be more useful in evaluation of the presence of ligamentous lesion s. For reasons of radioprotection , CT should be limited solely to the tract suspected of injury and should not be extended to the entire spine, as in adult s. A useful technique

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in th e stu dy of th e eervical spine is the use of bismuth shie lds to prot ect the thyroid, whi ch allow s a 30 % reduct ion in do se. The isotropic acqu isitions of volumetric multis lice CT enable mul tiplanar rec onst ru ctions , bon e maximum -int ensity proj ection s (MIPs), and thr ee-d im en sion al volume tr ic recon stru ction s. With the exce ption of severe multipl e trauma, where CT is indica ted as the fi rst-cho ice imaging mod alit y, the use of th e tec hnique in oth er cases should onl y follow clinic al-radiologic al evaluat ion . MR is ind icat ed in all cas es of spina l cord inj ury. The relative frequ ency of SC IWOR A in th e pediatric popul ation j ustifies its use in th e abse nce of rad iological abnor malities of th e spine. MR has th e ta sk of identify ing edema tous and ligam entous lesion s, spinal cord contus ions /lacerations, intra- and extra-ax ial hemo rrh age, subluxa tions/dis loc ations of the vertebral bod ies, occult fractures , or concomitant di sc lesion s. These alt erat ion s are found in 3 I% of patient s with norm al radiography.

6.2.3

Evaluation of Spinal Trauma One of the mo st impor tant requirements in the evalu ation of pedi atric traum a, parti cularly when the ce rvical spine is involved, is to establ ish whether the lesion is stable or un stable . Stab ility depends not only on the integrity of the radiologic ally visible osseou s struc tures , but also on the int egrity of th e po sterior mu scular, ligam entous, and cap sul ar struc tures . Th e rad iological study of a cervi cal spine inj ury is no simple matt er - it requ ires a good deal of exper ience . Clinical evaluation is always required, and may be abl e to rul e out the need for a radiological study. Of all the radiological views of th e spine , the lateral view is th e mo st impo rtant for eva luating its stability, particularly at the cervical spine. Th e radiological study di ffers on th e ba sis of th e degr ee of pat ient compl ianc e, if con sciou s, dro wsy, or unconscious. Wh en po ssibl e, radiog raph s in anter oposte rior and lat eral and odontoid op en-mouth views should be perfo rm ed, without mo ving the pati ent from th e tabl e. If th e op en-mouth vie w cannot be ach ieved (patient intubated) , then a CT study should be performed . In add it ion , in early infa ncy and in children up to 5 years of age, ac hievi ng the open-mouth view for the study of the odontoid pro cess can prov e di ff icu lt. Rad iog raph s in flexi on can be useful fo r ruling out or demonstr ating posteri or lig am entous and occult lesion s. CT is useful for the vis ua liz ation of intras pinal bon e fragmen ts and for evaluating th e stability of th e osseou s stru ctures . In th e study of the atl anto-occipital j oint, CT is useful in identi fying occult fractures of the occipital condy les . Many of the fract ures of th e odontoid process in ch ildren und er 2 yea rs of age occur at th e subdenta l synchondros is of th e axis and can be visuali zed in the lateral view. On e eleme nt for evaluating trauma at th e level of th e den s of axis is measur em ent of the predental width . The variations in pedi atric patient s are mu ch more important than in adults . In ch ildren, a dist ance of 3-4 mm can be con side red normal. Thi s can change significantly in po sit ion s of flex ion and extension, with vari ations usually of 2 mm. Th is fi nding should be evalu ated with care.

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Spec ific lesion s of the ax ial ske let on during growth include lesion s of the cartilaginous margins of th e vertebr al bod ies, and fractures at the level of the sy nchondrosis of the den s of the axis, atla nto-occipita l dislo cat ion typical among infants, and atl anto-axi s rot ational and tran slation al di slo cation s. Fractures of the odonto id pro ces s are ca use d by she ar forces, wh ich can occur in head-on ca r crashe s at spee ds of at least 40 km/h , ass ociated with sudden decelerat ion. In children , the verte bral bod ies have an oval appearance, and with growth th ey becom e cubo id and th en rectangular, and rare ly tak e on a flatte ne d appearance . The neur al arches and spinous proc esses show mark ed variability. Abe rrant bon e formatio ns in the skull base and cervi cal spine are frequ ent , which, unl ike frac ture fragment s, oft en present rounded marg ins. Th e verteb ral column in children, pa rticularl y th e ce rv ical spine, present s a number of physiological characteri stic s that should be well known and should not be erroneou sly interpreted as signs of traum a with dislo cation and /o r fracture (Table 6.2). Th e mu scl es of th e nec k are less developed, and compliance in th e bon es is gr eat er, which incre ases th e frequency of traumatic lesion s of th e soft tissue without assoc iated fractures . The anatom ical differenc es betw een the cerv ical spine of ch ildr en and adults are ma rked up to the age of 8 years, and th ey persist to a lesser extent unt il around 12 years of age. The development of the superior cer vic al spine is different from that of the inferior cerv ica l spine. The atlas (C I) develops from thr ee ossification centers (body and two neural arches). Abnormalities are pre sent when one of the se centers fail s to develop or there is fai led fusion . The po ste rior arch fuses normally at the ag e of 3 yea rs . The axis (C2) develops from fou r ossification centers (body, odontoid process, and two neural arches). The se are present at birth and they also fuse at the age of 3 years. The body and the odontoid proce ss are joined by the dentocent ral synchondrosis, and the body and the neu ral arche s are joined by two neurocentral synchondroses . The inferior cervical spine develops from three ossification Table 6.2 Cervical spine: physiological findings in pediatric patients Anterior arch of

I elevated in hyperextension

Increased interspinous distance between Increased distance between

I and

2 in flexion

I and the den ' of axis

Posterior vertebral body dislocation 2- 3 angle

Anterior dislocation of 2 on 3 (Hangman) Physiological wedging of 3 and 4 Epiphyseal ring Pseudo-widening of the spinal canal Pscudofractures due to erroneous placement of the superior cervica l spine Increase in the distance between lateral masses of infants <2 years

I and the dens of the axis in

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ce nters, on e central vertebra l, and two neural arches, also j oined by two neurocentr al synchondroses which fuse between the third and sixth year. The cervical and thoracic verte brae also have f ive secondary ossification cente rs (on e for the spinous process, two for the transve rse pro cesses, and two ring apophyses).

6.2.4

Pathophysiology Th e und erlying mechan isms of spinal trauma are flexion , lateral flexion , extensi on, rotati on, axial compressi on (Fig. 6.13) , and tear ing. Flexi on induces spina l lesion s more fre que ntly than extensi on (Fi g. 6. 14). The ana tomical characteristics of the various segme nts influence th e on set of various types of lesion s: th e hori zontal ori ent ation of the facet j oints of th e ce rvica l spine favor th e di slo cation and rupture of the inte rve rte bral disc without fracture. In cont rast, in the lumbar spine, th e prevalentl y vertical direct ion of the facets induces fra ctur es of the facet joint s th emselves and linear fractures of the vertebral bod ies. In the presence of seve re trauma, a di ssolution of the verte bral bod y may ensue ( Fig. 6. 15). In cases of child abuse, compression fractu re s ass ocia ted with hype rflex ion may be silent. If the verteb ral compres-

a

c

Fig. 6.13 Forces involved in the trauma mechanisms of the vertebral column. a Flexion (+%); b extension; c anterior (+%) and posterior rotation; d axial compression

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, avulsion

, ring-shape epiphysis ' compression

a

, distraction b

Fig. 6.14 Trauma mechanism. a Lesion resulting from flexion and anterior compression trauma ; b lesion resulting from trauma mechani sm in extension

Fig.6.1S Non-spinal cord injury in a 12-year-old girl obtained during karate training. Onset of pain . CT study performed 2 months after the trauma. a Sagittal MPR; h Ti -weighted sagittal MR; c T 2weighted sagittal MR. Dissolution of T8 vertebral body and alteration of the posterior wall (arrow) . The trauma has caused collapse of the vertebra affected by Lange rhans histiocytosis. Note the presence of pathological epidural tissue at the level of the posterior wall of the collapsed vertebra

sion is very marked, the differential diagno sis may includ e tho se alter ations result ing from mu eopol ysaecharido sis, Lang erhans ce ll histioc yto sis, or oth er condition s that favor vertebral fractures. Later al dislocation of the vertebral bod ies is usuall y associat ed with severe fractures . Radiological findings includ e alteration s of the inte rver tebral space width , an abno rmal confi guration of the facet jo ints, a wide ning of Luschk a's joints, a wid ening of the interspinous distance, a lateral shift of the spinous processes, and a widening of the interpedicular space . Establishing the pre sence of instability of the cervic al spine is based on the identification of specific radiological signs (Table 6.3), some of which are easily recognizable , wh ile for others, conventional radiology may not be enough and CT can play an important role .

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Table 6.3 Signs of cervical instability Anterior. posterior or lateral dislocation of the vertebral body Widening or narrowing of the intervertebral space Widened narrowed or dislocated facet joints Localized widening of the Luschka joints Bilateral or unilateral facet joint block cparation of the . pinous processes. sometimes associated with avulsion fracture Avulsion fracture in flexion or extension ompression fracture of the anterior border with posterior dislocation of the vertebral body involved Widening of the prcdcntal space: external dislocation of the lateral masses of (Jefferson fracture) nterior dislocation of one of the lateral masses of

I (rotatory di.location)

Fracture of the den . with or without di location Blow-out fracture of the vertebral body

6.2.5

SuperiorCervica l Spine Injuries The spine of neonates and childr en is part icularly vuln erable to distraet ion injurie s seeondary to lig amentous lesions of th e sup erior eer vical spin e. In child ren below 9 years of age, 78% of cerv ical spine inj uries are located in the superi or tract , and 68% are cha ract eri zed by sub luxation without fracture or SCIWORA. Atlanto-occ ipital di sloc ation is mo st common between 5 and 9 years of age . Spinal distract ions/d isjunction s are rare in children and often fatal du e to concomitant brain stem inj uries . Survi vors of such lesion s present severe tetrapl eg ia. There are certain pathological conditions that favor th ese lesions , including Klippel-Feil syndrome, Gri sel syndrome, and Down syndrome. Radiogr aphy of atlanto-occipital disjunctions/disassociations , done in the lateral view, should evaluate the BC:OA ratio by measur ing the basion and the posterior arch of C I (BC) divid ed by the distanc e between the opisth ion and the anterior arch of C I (OA). A ratio greater than 1.0 is con sidered diagno stic (normal value 0.77). CT is considered the imaging modal ity of choic e. MR provides an evaluation of the soft tissue and ligaments, and in particular can evaluate the presence of a tectorial membrane lesion .

6.2.6 Occipito-atlanto-axial Instability Th e atl anto -occipital joints enable the man euvers of extension and flexion and the con sequ ent tran slation of C I and C2. Movement s gr eater than 5 mm and 3 mm in

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Fig.6.16Sport injury in 14-year-old child. Axial CT scan. Jefferson fracture. Fracture of the left anterior arch of CI (long arrow), anterior to the transverse process, and disjunction of the bone fragments. Concomitant median fracture of the posterior arch of CI (short arrow). Lateral dislocation of the dens of axis due to the rotation of C I (round arrow) . Highly unstable lesion

ch ildren below and above 8 years of age, res pectiv ely, indicate th e pre sence of atlanto-a xial instability and lig amentous laxity, and/or a te ar of the tran sve rse ligament. Radiograph s in flex ion can be useful if done with care . Eva luating the pre sen ce of a rotatory subluxa tion ca n be done with dyn am ic CT to veri fy th e mo vem ent of the anteri or arch of atlas with respect to the den s of axis, with scans perform ed in any po sit ion and subse quent rot ation from both sides of the head on the neck. Jefferson frac tures of C I, th e res ult of an excessive load from above or a contrecoup of th e head secondary to a dive, are rare in pedi at ric age. Unlike in adults , where th e fracture tends to be ant erio r and po ster ior, in childr en it is more commonly a single fracture with pivot on th e sy nchondrosis (Fig. 6. 16).

6.2.7 Odontoid Process Fractures Frac tures of the den s in ac ute trauma are less common in children than in adults. The an terior angle of th e odontoid pro cess is highl y suggestive of a fracture in an ac ute trauma. MR is mor e sensi tive in iden tifyi ng bon e mar row edema acc ompany ing the frac ture line, particul arl y at th e level of the dentocen tral sy nchondrosis . (Fig. 6.17). CT provid es a detail ed evaluation of th e typ e of fracture and offers an evaluation of how chronic th e condit ion is. Ande rson and D' Alonz o have classified odon toid fractur es into three types: typ e I: avulsi on fracture secondary to a tear of the alar lig am ent. The presenc e of an os odontoideum can make th e diagnosis diff icult typ e II: tran sver se frac ture exte ndi ng to th e odontoid base, oft en with a d isjunction ( Fig. 6.18). Sag ittal and corona l reconstruct ion can be useful , given that the fracture may be missed in the axial plan e typ e Ill: the fracture exten ds to the bod y of C2 and is relati vely fre quen t in children below the age of 7 years . Oft en th e frac ture crosses th e dentocent ral synchondrosis. The synchondrosis stays open unt il lat e infa ncy.

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Fig. 6.17 Median (a) and paramedian (b) sagittal MPR. At the level ofC2 the normal appearance of the synchondrosis between the dens and the body of the axis can be identified, which should not be confused with a fracture line. Pseudo-anterolisthesis of C2 on C3, fi nding within normal limits. Normal atlanto-occipital relations

Fig.6.18 Non-spinal cord injury resulting from a road acc ident with hyperflexion of the head on the neck in a 5-year-old child. a Radiograph in lateral view. b Median sagittal MPR. c Axial scan at the level of the dens of the axis. An increase in the distance between the posterior profile of the anterior arch of Cl (arrow in a and double-headed arrow in c) and the anterior cortical profile of the dens ofaxis are visible, with integrity of the anterior columns ofC2, due to rupture ofthe transverse ligament of the odontoid process. Increase in the distance between the posterior arch ofC I and the spinous process of C2 (double-headed arrow in a) due to interruption of the posterior aponeurotic and ligamentou s complex subsequent to hyperflexion. Reduction in the transverse dimensions of the spinal cana l with sufficient dimensions to not exert compression on the spinal cord. Synchondrosis between the dens and the body of the axis is not yet completely fused (arrows in a and b); not signs offracture s at this level. Highly unstable lesion which requires fixation

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CT is diagno stic in difficult cases. Most of these lesions are the result of a posterior dislocation of the dens and can be highl y unstabl e and cause spinal cord compression . Widening of the synchondrosis and its anteri or angle are indicat ive of a lesion .

6.2.8

Extension Fractures of the Atlas and Axis The mo st common is fracture of the posterior arch of C I , follow ed by frac tures of the dens of the axi s and the classical Hangm an 's fractu re of C2 . Fractures of the poster ior arc h of C I may be unil ateral or bilateral , and can be isolated or associated with oth er fractur es. They can produce stenosis -induced lesion s as a res ult of the angle of the dens. CT is extreme ly useful in their evaluation. Hangm an 's fractures are characterized by bilateral frac tures cro ssing the neural arch es and the ver tebra l peduncles, tog eth er with ant erior ligam entou s disruption. Unilateral fracture of the arch can be mor e difficult to diagno se since there is usually no ass ociated instability of the posterior ce rvi cal spine . A Hangm an 's fracture in sma ller children may be silent.

6.2.9 Flexion Trauma of the Inferior Cervical Spine Thi s traum a cau ses lesion s of the vert ebr al bod ies and their respectiv e ligament s, the facet joints and their respective ligaments, and the spinous proc esses and their respectiv e ligam ent s. These lesion s are mor e common in old er child ren. The compression forces are located anteriorl y and the distraction forces posteriorl y. In many cases, a triangular avulsion lesion is present , most commonly at the level of the anterio r-po sterior edge of the avulsed vertebral bod y. Poster ior distrac tion forces, ass ociated with hyperfl exion-induced lesion s, produce ligamentous lesion s across the fac et joint s and between the neural arch es and the spinous processes. The dislocation of the vertebral bod y can be minim al, and dislocation of around 3 mm can be con sidere d abnormal. On the oth er hand, an anteri or angle great er than 12-15 ° should als o be considered abnormal. At the level of the neural arch and the spinous processes, the ligamentous lesi on produces a separation of the spinous proc esses involved and a wid ening of the inters pinous distanc e (Fig. 6. 19), and, mor e rarely, avulsion fractures of the posterior ele ments. If there is an altera tion of the ant eropo sterior long itud inal ligament s, the ligam ent s of the fac et j oints, the neural arch , and the spinous proc esses, then the res ult will be instabil ity (Figs. 6.20 and 6.21). MR is part icularl y useful in ide ntify ing osteo-Iigamentous alte rations .

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Fig.6.19 Trauma mechanism in flexion of the cer vical spine

Fig. 6.20 Complete disjunction between C5 and C6 (double arrows) in a 6-year-old child, with resulting acute tetraplegia, subsequent to a road accident. a Pre-fixation anteroposterior view, and b post-fixation lateral view radiograph s. Reduced-height of C6 (arrow)

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Fig.6.21 Sagittal MR of the same patient as Fig. 6.20. The vertebral disjunction between C5 and C6 can be identified (arrows). Extensive posterior fascial and ligamentous lesion (double arrows). Extensive spinal cord inj ury with focus of hemorrhagic laceration-contusion, and marked bone marrow edema extending for around seven segments (red arrows)

6.2.10

Extension Trauma In extension fra ctures, the tear involves the anteros uperior edge. If, instead, the re is evidence of a teardrop fra cture, it is corr ect to suspect an un stable lesion induced by hyperflexion. In ch ildren , the equivalent of the fracture con sists of slipping of the normal vertebral epiphyseal ring. Extension lesion s are characterized by the presen ce of po ste rior compression forces and anterior distraction force s, with fractu res prevalently invo lving the facet joints, the columns, and the posterior elements . Widening of the interverteb ral spa ce occurs as a re sult of rupture of the anterior longitudinal ligament induced by extension , with invo lveme nt of the super ior edge of the vertebral body. The prevertebral tissue swells only in the presence of rupture of the anterior longitudin al ligamen t. If the frac tures of the po ste rior arch are un ilate ral, the fracture is not particularly un stable ; in cont rast, it will be if the fractures are bil ater al.

6.2.11

Fractures of the Thoracolumbar Spine Frac ture -dis locations of th e thoracolumbar spine are usually cause d by high- energ y trauma. They are uncommon (2.5 % of al1 spina l injuries) and invol ve multipl e verte brae in 50- 70% of cases . In trauma pati ent s age d over 8 years, th e rad iological presentati on is si mi lar to that in adults, wher eas below 8 yea rs of ag e, th e finding of

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SC[WORA is not uncommon even in this tract. They are frequently caused by a fall from a height, for example from a trampoline (Fig. 6.22). An angle of less than [0 ° of the spinal axis simply requires bed rest , whereas a greater angle requires immobilization in extension for 2 months. A vertebral compression greater than 50% requires surgical stabilization. The fractures can involve each of the three columns described by Denis. Instability also needs to be evaluated at these levels (Fig. 6.23). The finding of a fracture is more common than a dislocation of the vertebral bodies or the presence of a compromised disc, since the ligamentous structures offer greater resistance than bone. In seat-belt injuries (most commonly at L I-L3), an anterior compression of the vertebra can be observed, tog ether with associated lesions of internal organs. Radiological study, done with CT, should identify the presence of free bone fragments dispersed in the spinal canal, and the presence of fractures if the neural arch and the facet join block. Vertebral compression is the most common finding. The presenc e of a lesion at the level of the thoracolumbar joint in patients aged less than 2 years suggests the presence of a non-accidental injury. In cases of minor compression, a lesion can be identified at the edges of the vertebral body, which appear squashed, and the vertebral end plates have a concave appearance . [n cases of intermediate compression, the anterior wedge shape of the vertebral body or loss of the concavity of the posterior wall can be identified. In cases of severe compression, collapse of the vertebral body is evident, appearing flattened with an alteration of the posterior wall and possible spinal-cord compression . Growth plate fractures (Salter-Harris I or 11), with or without associated protrusion of the intervertebral disc , are encountered in adolescent patients. Avulsions with fragments of lumbar processes and fractures of the transverse processes may be

Fig. 6.22 CT of the thoracolumbarspine in multiple trauma with no spinal cord involvement in l2-year-old child. a Bone MIP. b Coronal MPR. Fracture of L2 due to hyperflexion and vertical compression Depression of the vertebral plate with anterior wedge and blow-out fragments in lateroanterior location (arrows). There are no signs of alteration of the posterior arch. Stable fracture

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Fig. 6.23 Fracture in hyperflexion with fulcrum on L2. a-c Sagittal MPR. Posterior instability. Small antcrosuperior displacement of the vertebral border (arrowhead in b), transverse fracture with diastasis of the neural arch and vertebral peduncles with posterior opening due to avulsion with laceration of the corresponding soft tissue (small arrow in h and arrowhead in c). Widening of the Ll -L2 posterior intervetebral space (double arrow in a). Transverse fracture of the upper vertebral plate and the posterior apophyseal complex (double arrow in b)

found . Even in minor traum at ic lesions, th er e may be severe lesions of th e inte rn al organ s (60 % involvi ng the kidneys, 35 % the live r) . A specia l type of lesion is the Cha nce fra cture, which is cha ra cterized by a bil ater al di slocat ion of the fac et joint s, fracture of the ver tebra l peduncles or the laminae of the neural arc h, and extension of the fracture line a long the vertebral body (Fig . 6.23) . These lesion s, which may be di ff icult to diagnose both with con ventional radiography and CT, ar e not uncommon in sea t-belt injuries. Case s of traum atic spondylos is ar e rare .

6.3 The Thoracic Cage 6.3.1

Chest Wall Injury Ches t wall inj uries are particularly important since they usuall y occur as a result of trauma that ca uses severe asso ciat ed lesion s. Gi ven that th e ri bcage in children is mo re elas tic than in adul ts, less ene rgy from a blow is absorbe d by the ches t wall , and proportionally mo re energy is tran sferred to th e intrathoracic organ s (which ca n cause, for exam ple, pulmonary contusion s). Int ernal lesion s ar e oft en present in the ab sen ce of vis ible damage to the ch est wall itse lf. A ri b fracture sec on dary to close d thoracic tr auma is an im portant ind icator of the seri ousness of the trauma itsel f. Th e greater the number of fra ctured ribs, the mo re seri ous the complicat ion s ar e. The mo st common cau se s of chest wall injuries are roa d acci dents, although the se lesions ar e frequently pre sent in victims of child abuse. Mortality is usuall y the re sult of ass ociated traum a, particularly he ad injurie s. In the vari ous studi es publi shed in

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the literature, the mortality resulting from chest wall inj uries alone vari es between 4% and 14%, whereas in cases with associated head inj ur ies the percent ag e rises to 28-37%. Chest wall inj uries in children differ from tho se in adults, given the great er flexibility of th e structures of th e ribcage . Flail chest, which is the result of multipl e fractures of a rib producing a fre e segment , is rare in children. An early diagnosis is requ ired to avoid con sequ ent pulmonar y compl ications. The proportion of patients treated con servatively is around 97% in rib fractures. Rib fractures are associated, in decreasing order, with injuries to the extremities, skull , spl een , and liver, sternal and scapular fractures, rupture of th e thoracic aorta, and, rarel y card iac lesion s. Stern al fractures are rare in children and can be th e result of dir ect or indirect trauma. Th ey gen erally arise as the result of clos ed trauma of not excessive kin etic energy. Special att ention ne ed s to be paid, in cases of high-impact sternal fractures, to concomitant spina l inj uries . Ant erior cortical fractures are common, whereas fractur es of the manubrio sternal joint are rare (Fig . 6.24) . Stern al fractures are not uncommonly as sociated with spinal inj ur ies in hyperflexion of the thoracic spine , with forc e lin es being transferred to the sternum by the cla vicl es as a result of muscle action in hyperextension of the chest. In healthy children, fra ctured ribs are highly speci fic for child abuse. Acute rib fractures can be difficult to identify at chest radiography. Bone scintigraphy or CT may be needed to evaluate acute-phase fractures. However, the se techniques are not indicated unless it is necessary to identify associated lesions of the pulmonary parenchyma or vertebral column. Most fractures can be identified two weeks after the trauma th anks to the form ation of fibroc artil age callus. In the first 3 years of life , rib fractures constitute a positive predictive value for child abuse. Fractures resulting

Fig. 6.24 Multiple traumafollowing a roadaccidentina 14-year-oldchild. a Lateral view radiograph, and h sagittal CT MPR. Fracture-luxation of the sternal manubrium is visible. No pulmonary lesions belowthe fracture can be identified. No clavicularlesions

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from abuse are most commonly located at the level of the posterior arches, in proximity to the transverse processes. In infants in their first year of life, around 80% of cases are the result of child abuse , while the remaining 20% are due to direct trauma or metabolic disease . These fractures are very rare in neonates. They may also be the result of resuscitation maneuvers (0 .6%). Radiographically, they are recognizable as lucent lines at the level of the costal arch; oblique views are useful for their identification .

Suggested Readings Anderson LD, D' Alonzo RT (1974) Fractures of the odontoid process ofthe axis. J Bone Joint Surg 56A:1663-1674 Chapman VM, Fenton LZ, Gao D, Strain JD (2009) Facial fractures in children : unique patterns of injury observed by Computed Tomography. J Comput Assist Tomogr 33(1):70-72 de P Djientcheu V, Njamnshi AK, Ongolo -Zogo Pet al (2006) Growing skull fractures. Childs Nerv Syst 22(7) :721 Ersoy G, Karciog?lu 0 , Enginbas , Y et al (1995) Are cervical spine X-rays mandatory in all blunt trauma patients? Eur J Emerg Med 2(4):191-195 Grotboom MJ, Governer S (1993) Acute injuries of upper dorsal spine. Injury 24(6):389-392 Leone A, Martino F (eds) (2008) Imaging del rachide. Springer-Verlag Italia, Milano Losee JE, Afifi A, Jiang S et al (2008) Pediatric orbital fractures : classification, management, and early follow-up. Plast Recostr Surg 122(3):886-897 Martin BW, E Dykes, Lecky FE (2004) Patterns and risks in spinal trauma, archives of disease. Childhood 89:860-865 Mehta S (2007) Neuroimaging for paediatric minor closed head injuries. Paediatr Child Health 12(6):482-484 Moore MA, Wallace EC, Westra SJ (2009) The imaging of paediatric thoracic trauma . Pediatr RadioI39(5):485-496 Quayle KS, Jaffe DM, Kuppermann N et al (1997) Diagnostic testing for acute head injury in children : when are head Computed Tomography and skull radiographs indicated? Pediatrics 99(5) :EII Shane SA, Fuchs SM (1997) Skull fractures in infants and predictors of associated intracranial injury. Pediatr Emerg Care 13(3):198-203 Struffert T, Grunwald I, Reith W (2003) Craniocerebral trauma in childhood . Radiologe 43( II ):967976 Thornton A, Gyll C (eds) (1999) Spine in children 's fractures . WB Saunders, Harcourt Publishers Limited UK pp 90-105 Tung GA, Kumar M, Richardson RC et al (2006) Comparison ofaccidental and non accidental traumatic head injury in children on noncontrast Computed Tomography. Pediatrics 118(2):626233 Tiiredi S, Hasanbasoglu A, Gunduz A, Yandi M (2008) Clinical decision instruments for CT scan in minor head trauma . J Emerg Med 34(3) :253-259

7.1 The Shoulder and Arm In children, the clavicle (coll arbone) is one of the bone s that is most susceptible to fracture . In most cases, immobilization is the preferr ed cho ice of tre atment; onl y in exceptional cases does surgery prove necessar y, and thi s is con fined to cases where there is a simple frac ture with exposure of the bone. Fractures in neonates may be caused by natural deliver y, especi ally in macro somi c children weigh ing more than 4 kg, or by comp ression traum a of the shoulders in the cou rse of dystocic deli ver y. In old er childr en, the traum a most commonly res ponsible for fracture is a fall on the shoulde r with direct trauma, or with an out stretch ed arm. Most fractures involve the middl e third of the clavicular diaph ysis, making A-P X-ray proj ection suff icient for diagnosis. However, in neonates and very sma ll children, incompl ete lesion s with a thin frac ture rima and normal bon e alignm ent are common, and are sometimes mistak en dur ing X-ray diagno sis due to their small size or to their position , which is not tang ent ial to the rad iog raph ic beam. In these cases, where the symptoms (tum efact ion , immobility, pa in on mob il izat ion) do not corre spond to the negative fi ndings from X-ray, ult rasound may identi fy sma ll breaks without the need to res ort to additiona l X-ray projection s (Fig. 7.1a, b). In these cases, the fracture can then be vis ualized by X-ray through furth er check-ups that can identify the presence of a reparative callu s (Fig . 7.1c, d). In neonates, discovery of a fracture of the acromial extre mity of the clavicle rai ses suspici ons of non-accident al lesion s caused by abu se. In old er children and adolescent s, fractures are mor e frequ entl y simple fractures, with lowering of the shoulder on the affected side, loco-regional tum efactio n, and pain; treatm ent is based on immobilization through "fi gure-of-e ight" bandage.

D. Barbuti (C8J) Depa rtment of Diagnostic Imaging, Pediatric Hospital " Bambino Gesu", Rome, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20 I I

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Fig.7.1 Fracture of the clavicle. 3-year-old girl with a suspected fracture of the clavicle which did not emerge in X-ray (a), while ultrasound (b) reveals a slight interruption of the bone cortex at the level of middle-outerthird. X-ray of the clavicle of an II-month-old baby boy in which there is clear angulation of the clavicle without clear visibility ofthe fracture rima (c), while at a checkup performed after 20 days (d), the fracture rima and the osseous callus for osteoreparative phenomena can be clearly identified

Dislocation of the clavicle is rare in pediatric age. Fractures of the lateral portion of the clavicle are more frequently observed in connection with the acromioclavicular articulation, while fractures at the level of the sternoclavicular articulation are extremely rare and involve the physis (type I or 1\ Salter-Harris fractures). Avulsion of the middle physis with posterior dislocation of the fragment may cause compression of the trachea, the subclavian vessels, or the brachial plexus. Assessment of this type of lesion can be made by computed tomography (CT) blurring, which makes it possible to record the position of the dislocated fragment from behind and to identify further complications that provide useful indications for surgery. Scapular fractures arc rare and generally caused by high-energy traumas; they arc often associated with traumatic lesions of adjoining skeletal structures (clavicle, ribs, dorsal vertebrae, humerus) or with pulmonary lesions (lacerations/contusions, aeropleura). Traumatic lesions most frequently involve the coracoid (Fig. 7.2) , the acromion, and the glenoid, and may be associated with lesions of the acromioclavicular articulation and glenohumeral articulation. The numerous nuclei of ossification of the scapula may resemble fracture lesions. Fractures of the neck and body of the scapula are rarer in pediatric age compared to adults and arc generally caused by a direct trauma of significant extent (Fig. 7.3) . A-P and L-L X-ray projections of the scapula are generally diagnostic; CT can provides further information, especially for fractures of the neck of the scapula, highlighting the extension of the rim fracture to the glenoid. Traumatic lesions of the proximal extremity of the humerus are more frequently represented by epiphyseal separation and by fractures of the proximal metaphysis of

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Fig. 7.2a, b Avulsion of the coracoid. The comparative X-ray examination of the shoulders in axial projection shows a detachment of the left coracoid (arrow in h)

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,~

,

.

-, A,

4 I "/

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-,

Fig. 7.3 Fracture of scapula. CT axial scan which shows a slight fracture rima of the body of the scapula (arrow) in a 16-year-old polytraumatized patient

the humerus; the latter are more frequent in stage I and II childhood (Fig. 7.4) . X-ray assessment of this type of lesion must be performed in the transthoracic frontal and lateral projection, in order to check the alignment of the bones in orthogonal planes. The presence of dislocation of the humeral head provides indications for surgery; in these cases, it is advisable to perform a CT examination, complete with 3D reconstructions, in order to assess the position of the bones more precisely (Fig. 7.5) .

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Fig. 7.4 Fracture of the proximal metaphysis of the humerus. a A-P X-ray of a seven-year-old patient with a proximal metaphysis of the humerus with interlocked fragments and minimal varus angulation. b, c A-P and axial projection of an eight-year-old patient with a compound fracture of the surgical neck of the humerus

Fig.7.5 Fracture-dislocation of the humeral head. a A-P projection (scout-view) shows the presence of the fracture-dislocation of the humeral head (IO-year-old child). b CT, complete with 3D reconstructions, shows with more precision the position of the bone heads and the type of dislocation for surgical purposes. c In the X-ray check-up, in plastered immobilization after surgical synthesis with two metal wires, good alignment of the bone heads and a reduction of the dislocation can be observed

Factures of th e proximal epiphyseal nuel eus of the hum erus are more rarely ob ser ved . Traumatic detachm ent/separation of the proximal e piphysis of the humerus, almost exclusively of types I and 1\ according to the Salter-H arri s cl assi fi cation, can sometimes be mo re difficult to detect using X-ray, especially in case s where the epiphysis is still completely cartilaginous; when the di agnosis is uncertain (p articu larly in case s of Salter-H arris type I sepa ration, without bre ak s, cau sed either by acute lesions or ch ronic trauma as in the case of " litt le le ague shoulder" , the lat ter be ing particularly common between the age of 12 and 15 years), ult rasound, and particularly magnetic resonance imaging (MRI), can be helpful in making the diagno si s (F ig. 7.6) . Pro xim al e piphyse al sep ar ations of the hum erus are more fr equent in adole sce nts, generall y du e to falls on the abducted limb or as a re sult of direct trauma. Compl ications are rar e, an d it is more common to ob serve sho rt ening of th e

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Fig. 7.6 Proximal epiphyseal separation of the humeru s ("little league shoulder"). A-P projections and gradient-echo coronal MRI scans, performed for comparative purposes on a 12-year-old boy. a, b Definite lesions of the physis cannot be recognized with X-ray. c, d MRI shows a widening of the left proximal physis on the internal side (arrow ) in relation to a type I Salter-Harris fracture

humerus as a result of damage to the growth cartil age . Dysmet rias can be a signifi cant and inc apac itat ing con sequence of le sion s of the physis, and the ir extent is propo rtional to the growth potential of the carti lage concerned. In the upp er limb , the proximal phy sis of the humerus cont ributes about 80% to the growth of thi s long bone while the distal phy sis contr ibutes only about 20 % by its di stal physis, wh ich is why lesion s of the prox imal physis are mo re frequently ass ociated with dysmet rias, including tho se of a serious natu re . In the forearm , mo st of the bone growth involves blurring of the distal physis (about 75% for the radius and 80% for the uln a). In the case of fra ctures of the proximal humerus with a case hi stor y of a slight traum a, it is also nece ssary to exclude the pre sence of pathological fracture s since the humerus is the mo st frequent site of benign bone lesion s, part icul arly solitary bon e cysts. Tra umatic dislocat ion s of the glenohumeral articulation are generally ca used by indirect traum as; in mo re than 90% of cases, thi s invol ves anterior disloc ations, while poste rio r and inferio r di slo cations are less frequent. In the case of anterior dislocation, the pat ient keep s the limb abducted and rotated inwar ds . Although the diagno sis of di slo cation is cl inical, an X-r ay examination is important for identifying the pre sence of po ssible fractures ass ocia ted w ith the glenoid or hume ral head (H ill-Sach s lesion) ( Fig. 7.7), and to che ck for correct articular relationship s following th e reduc tion man euv er (Fig . 7.8) . As in adults, MRI is bett er for record ing bon e lesions and lesion s of the circumfe rentia l cartilage . One of the possibl e complic atio ns of shoulder dislo cation is lesion of the ascell ar nerve, osteon ecrosis of the hum eral head, and previou s shoulde r dislocations.

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Fig. 7.7 Hill-Sachs fracture . Gradient-echo coronal MRI scan (a) and axial Tr-weighted scan (b), which show the presence of an impact lesion (arrows) of the humeral epiphysis in relation to a Hill-Sachs fractur e in a previous dislocation of the shoulder

Fig.7.8 Scapular-hume ral dislocation in a 15-year-old patient. A-P projection (a) and tran sthoracic projection (b) which show the presence of an inferior dislocation of the humeral head. eX-ray check -up after reduction shows restoration of the joint relation s and also shows the presence of a Hill-Sachs impact lesion

Fr acture s of the humeral di aphysi s are more commonly ob served in neonates fol lowing tr auma during delivery an d req u ir e clinical assessm ent to exclude a le sion of the brachial plexus . In older children, an attendant tr aum atic le sion of the radial n erve is qu it e fr equent in th e long course of th e humeral groove .

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7.2 The Elbow and Forearm The elbow of a chi ld is a highl y complex ana tomica l reg ion linked to the presen ce of num erou s growth nuclei which appear at different ages, with an interval of about 2 years between eac h one, although th ere is wid espr ead variabili ty. Girls also display earlier app earance of ossif ication nuc lei by about I or 2 years comp ared to boys. Th e acronym CR[TOE and identifi cation of this with th e "ru le of odd numb ers" ([ ,3,5 , 7, 9, I l ) represent useful methods for memorizing the chronological order of appearance of the different secondary nuclei of ossif ication and, for each one , the avera ge age of appea rance : capitellum (humeral cond yle - [2 months), radiu s (radial head - 3 years), internal (internal epicondyle - 5 years), trochlea (7 years), olec ranon (9 years), extern al (external ep icondyle - [I year s) (Fig. 7.9).

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Fig.7.9 Diagram (a, b) and X-rays (c, d) which illustrate the nuclei of ossification of the elbow of a 10year-old girl

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Due to th e difficulties linked to th e ra diological assessme nt of traum atic lesions of the elbow, oth er lin es of referen ce, o r indirect ra diographic lines, ha ve been prop osed, whi ch can help the radi ologist to interpre t X- ray im ages. Th e anterior humer al line is a straight line that is tangential to th e anter ior cortic al surface of the humerus in the lat eral proj ection and whi ch, in normal conditi o ns , inte rsects th e rad ial ca pite ll um at the level of th e m iddle th ird ; in th e case of suprac ondy lar frac ture w ith po ster io r dislocat ion, th is line cro sses th e anterior thi rd of the capitellum or is po sition ed ant eriorly to it (Fi g . 7. 10) . In orthogonal proj ectio n s, th e rad io- condylar line is a line tha t pa sses throug h th e axis of th e distal di aphysis, wh ich sho uld intersect th e hum eral condy le; if th is is not th e case , th is is a sign of d islocation of th e radia l epiphys is (F ig . 7. 1Ob). A "teardro p" is represent ed, in the lat eral proj ect ion of th e elbow, by th e cortical profile insi de th e coronoid fossa (ventrall y) or th e olecran ic fo ssa (dorsall y) and by th e humeral condyl e whi ch represents th e inferi or por tion ; if th ere is a suprac o ndy lar frac ture of th e humerus, thi s leads to deformation of th e ima ge of th e "teardr op" . Ob viou sly, the reliab ility of indi rec t radiologica l signs dep end s entirely on the techn ical precisio n with wh ich th e elbow X- rays are perform ed .

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Fig. 7.10 Frontal schematic representation (a) and lateral schematic representation (b) of the elbow durin g growth. c, Radiographic projection (lateral) of the elbow: clear articular effusi on without recognizable fracture; d presence of supracondylar fracture with articular effusion. The anterior humeralline (red and black dotted line in the X-rays), normally intersects the intermediate portion of the humeral condyle. In the case of a supracondylar fracture with angulated distal fr agm ent , t he hum e ral condyle is posterior to this line (d). The radiocondylar line (continuous red line in h) centrally intersects the humeral condyle nucleus. The "teardrop" can be seen in pink in b

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Suprac ondy lar fractures re present th e mo st frequent type of elbow fract ure in pediatric age (about 50%) and constit ute rou ghl y on e-th ird of limb fractures in th is age band . In general , th ey occur in ch ildr en aged 3- 10 years, with a peak rat e between 5 and 7 years of age. In 96-98% of cases, suprac ondy lar frac tures are cau sed by a fall on an outstretch ed hand with an extended elbow (hyperext ension fractures ) (Fi g. 7. 11a, b); this traumatic mechan ism ens ures that the uln a and tric ipital mu scl e exer t an opposite for ce on th e d istal hum erus, with po sterio r dislo cation of the distal fra gme nt of th e fract ure . Mor e rarely, in 2-4% of cases, supracondylar fra ctures occur following direct traum a to the dor sal part of the flexed elbow, with ant eriorlat eral d islo cation of the distal fragme nt (fl exion fractures ) (Fig. 7. I Ic, d) . In the case of supracondy la r fracture , th e exami nati on mu st be aimed at assessing the tum efacti on and the vasc ular and ner ve struc tures . Anter ior dislo cat ion of th e pro ximal bon e fragme nt can lacerate the brachial vessels or cau se dam age to the med ian ner ve. Conspic uous tum efact ion mu st rai se th e suspici on of a po ssibl e compar tme nt syndrom e. In th e ca se of a defect or weakn ess in the ar terial pul se, it is necessar y to perform a Doppl er exami na tion of the vessels distal to the frac ture site . Supracondylar fractures in hyperexten sion of the elbow can be cla ssifi ed into thr ee types according to Gartl and ( Fig. 7. 12) :

Fig.7.11 Supracondylar fractures of the elbow. They can be divided into extension fractures (a, h; frequency 96-98%), and flexion fractures (c, d; 2--4%)

Fig.7.12 Classification of supracondylar fractures according to Gartland. a Type I; b type II; c type III

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type I: undi spl ac ed type II: displaced, with angulated fragments and intact poster ior cortex type III: compl etel y displ aced with posterior dislo cation of th e distal bon e fragment and no cortica l contact. The main aim of this cla ssification is to distingu ish sta ble fractur es (ty pe I and II), for which con ser vative treatment may be sufficie nt, from unstabl e fractures (type III) where surgery is necessary. In si mple fractures, it is not always possibl e to obtain clear vis ualizati on of th e fract ure using X-rays, so care ful att ent ion should be paid to assessment of indirect signs tha t are useful for diagno sing concealed fractures . The fat pad sign is a specific report of hem arth rosis, or mor e generally of art icular effusi on, and is represented by a rad io-tran sparent image with triangular wedges, which can be visualize d in the latera l proj ection of the elbow, both in front of the anteri or pro file of the distal po rtion of the hum eru s, above th e coronoid fossa, and behind the posterior cortic al pro fil e of the hum eru s above th e olecran ic fossa. A mod est dislo cat ion of the anterior fat pad may be no rmal ; on th e oth er hand , a con spi cuous dislo cation with the app earanc e of the sail sign indicates distensio n of the joint capsule and, the refore , in th e absence of cle ar evidence of a fra cture in a traum at ized elbow, can be taken as an indir ect sign of a con cealed fracture. Visualiza tion of the posterior fat pad is never a normal report and even in the cas e of no direct visua liza tion of the fra cture, immobiliza tion of the elbow and a cl inical and radiographic follow-up is required, as if it were a simple supra condy lar fracture (Fig. 7. 13) . Fracture of the humeral condyle (Fig. 7. 14a ) is generally the consequence of a fall on an outstretched hand and repre sent s the mo st commonly ob served traum atic le sion in the pediatric elbow, after supracondylar fractures, representing about 20 %; fra cture of the trochlea is a rare event and should not be con fused with a det achment of its growth nucleus. The X-ray image of a fracture of the lateral condyle is generally

Fig. 7.13 Concealed supracondylar fracture. a Diagram illustrating the tumefaction of the soft tissues with displacement of the fat pad signs. b L-L projection which does not show signs of fracture, but dislocation of the fat pad signs of the elbow (ar rows). c L-L projection carried out 15 days later, which shows the appearance of reparative periosteal apposition (arrow)

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represe nte d by the presence of a metaph yseal bon e frag ment with poster ior dislo cation (Thurston -Holl and fra gmen t) . In th e case of a fractur e with minimal dislo cat ion of the bon e fragme nt ( Fig. 7.14 b), the diagno sis may prove probl emat ic and it is useful to perform obl ique proj ection s of the elbow; in th e event of a slight dislocation, th e bon e fragme nt may be confused with a centr e of ossification . MRI and ultra sound can be used to assess the exte nsi on of th e fractur e of the lateral cond yle to the distal epiphyseal car ti lage of the hum eru s. Fractures of the lat eral hum eral condy le have an obliqu e course (from the out side inwards) and gen erall y affect the hum eral distal metaphysis; th ey run through th e physis and the epiphysis, and distall y reac h th e joint surface of the elbow. Although rarer, it is also possibl e that th ere are fractures that do not involve the distal hum eral metaphysis. According to the Milch classification , th ese fra ctur es can be distinguished on the basis of the poi nt at which they reac h the joint surface : typ e I: these reach the j oint at the condy lar groove lateral to the trochlea . In th is type of fracture the fragments are generall y angled but the fractures are sta ble typ e ll: th ese reach th e joint surface mo re med iall y, involving th e apex and the externa l third of the trochl ea. In th is second type of fracture, the head of the rad ius and the olecranon can be dislo cat ed laterall y and th e elbow j oint proves unstable (subluxed or late rally di slo cated) . Both type s of fractures require " open sky" reduction and internal f ixation in case s whe re the re is diastasis of the distal fragment that is ~ 2 mm , due to the risk of unsuccessful con solidation of the fracture or subsequent disloc ation of the bone 's head s.

Fig. 7.14 Fracture of the humeralcondyle with(a) and without (b) dislocation of the bone fragment (different patient in b)

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Distal humeral epi physeal fract ure -se par at ions are normall y Salt er-H ar ris ty pe I av ulsi ons, more fre quen tly ob served in childre n age d und er 2 years, and gen erall y cause d by rot ato ry or she aring for ces. In old er childre n, they ma y be the consequ en ce of a fall with an outstr etch ed hand. In radiological term s, d istal humeral epiph yseal fracture-separa ti ons with com pletely car ti lagi nous nucl eu s may be diff icul t to distingui sh from dislo cation of th e elbow. In th ese cases, ult rasound is useful for a correct diagno sis ( Fig . 7 .15). Avulsi on of th e epit roc hlea re presents m ore th an 12% of tr aumatic lesio n s of the elbow in ped iatri c age , and is very freq uently asso ciat ed (in 50 % of cases) with d islocat ion of th e elbow. Th e lesion is mo st comm on in chi ldre n ag ed between 7 an d IS years, an d is fre que ntly ob ser ved in sports activi ties in re lat ion to valgus stress. Th e epitrochlea is th e se at of inserti on of the m ed ial colla ter al ligam ent and th e flexor mu scl es of th e for earm. In chi ldren ag ed over 6-7 ye ars , avulsi on of the epit roc hlea can easi ly be iden tified on X-ray since it is ossified (Fig . 7 .16) . In th e case of violent av ulsive lesion s, th e se parate d nucl eu s can be d istally di slo cat ed in th e hum eroulna r ar ticulati on, wh er e it can rem ain incarcerated betw een th e join t head s, with conse que nt d iasta sis of th e j oi nt head s. In smalle r chi ldre n, wh er e th e epitrochle a is sti ll not ossifi ed, in th e case of clinical sus pici on, a compar ative radiog raphic study of the elbows is requ ired, since demonstr at ion of the indirect sig n of enl argement of the medial articular spa ce may be the onl y sign of an avuls ion of the cart ilaginou s

Fig.7.15 Distal epiphyseal se parati on of th e humerus. a The A-P proje ction shows a medial dislocation of the bone of the forearm with respect to the humerus. b Ultrasound of the affected side shows a misalignment of the cartilaginous distal epiphyseal nucleus of the humerus with respect to the metaphysis in relation to the epiphyseal separation. c The ultrasound examination of the healthy side highlights a normal alignment of the distal cartilaginous nucleus of the humerus with respect to the metaphysis

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Fig. 7.16Avulsion of the nucleus of the epitrochlea in two patients of different ages: ossified (a) and cartilaginous (c, d). a Avulsion of the nucleus of ossification with separation of a small block of bone of the trochlea (arrow) in a IO-year-old boy. b In a seven-year-old boy, the X-ray examination shows a small osseous formation (arrow) including the cartilaginous epitrochlear nucleus (asterisk) detached from the humeral margin with diastasis ofthe humerus. d Normal position of the cartilaginous epitrochlear nucleus (asterisk)

ep itrochlear nucleus and its incarcera tion between the joint head s. In the se case s, con f irm at ion with ultrasound is cle arl y ve ry useful. Asse ssment of the extent of disloc ation of the det ach ed nucleus is funda menta l for the cho ice of tre atment. Indeed, avuls ion of the ep itrochlear nucleus require s surgical reduction if the extent of the dislocation is 2': 5 mm . MRI is useful for demonstr ating the presen ce of a part ial lesion of the medial collateral ligament, generally cau sed by function al overload in young athletes, in the abse nce of radiograph ic signs of avulsi on of the epitrochlear nucl eu s (Fig. 7. 17). In the case of fra ctures with con sp icuous dislocation of the fra gment, there may be ass ociated lesions of the uln ar ner ve whi ch star ts in th e epitrochlearolecran ic groove . Other fai rly frequent complicat ion s th at ar e also worth noting are joint rigidity and un successful con solidation of the fragment. A frequently ob ser ved traum at ic event, wh ich doe s not require a radiogra phic examina tion, is pain ful pron ation; thi s consists of di straction of the annular ligament and is generally found in sma ll chi ldren up to the age of 4 years : unt il th is age, the di ameter of the radia l capitellum and th at of the radia l neck are the same . Th is ana tomic condition pred ispo se s the patient to di straction of the lig ament following traction of the elbow with the ar m pron ated and out stretched . Dislocat ion of the elbow, which is rare in pedi at ric age, is mo re common among adolesce nts and is mo st commonly ass oc iated with bon e fractures. Poster ior dislocations, which ar e mo re frequent, are generall y caused by fall s with the arm outstretche d or parti ally flexed and supine, whereas anter ior dislocations occur as a re sult of direct traum a such as a fall on the olecranon. Medi al or late ral dislocat ion s ar e the conse que nce of a d irect or rotat ory trauma. Th e cl in ical pictu re is dom inat ed by intense pain at any attempt to mo ve th e joint ; a careful periph eral and vasc ular neurologi cal cl in ical ex ami na tion is important to h ighl igh t po ssibl e ass ociated lesion s of the adjoin ing vasc ular- nerve struc tures (brac hial art ery, med ian ner ve, and

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Fig. 7.17 Partial lesion of the ulnar collateral ligamentof the elbow.T2-weighted gradientechocoronalMRIimagewhichhighlights an alteration in the signal of the proximal portion (arrow) of the ligament due to distractive results without diastasis of the nucleus of the epitrochlea

ulnar nerve) . Besides identifying the type of dislocation, the radiographic study should be aim ed at identifying the associated bone fracture lesions; if performed after reduction, CT will be able to ensure better identification and definition of the site of detachments (Fig. 7.18) . Elbow dislocations are often associated with avulsion of the epitrochlear nucleus which, during reduction, can remain trapped between the humero-ulnar joint heads. Fractures of the olecranon are infrequent (5-7 % of elbow fractures in pediatric age), because the olecranon of small ch ildren is cartilaginous and in older children it is protected by an extremely thick peri ostium; in general, these are incomplete fractures without significant displacement. In nearly half of cases, they are associated with fractures of other bones of the elbow (Fig. 7.19) . Traumatic lesions of the prox imal extremity of the radius consist more commonly of fractures of the radial neck, since the epiphysis is cartilaginous until the age of 3-6 years, and is therefore more resistant to traumatic lesions. Prox imal fractures of the radius are caused by a fall on an outstretched hand with the elbow extended and deviated in the valgus position , and are associated, in 50% of cases, with other fracture lesions of the elbow that involve the same traumatic mechanism . Fractures of the radial neck vary widely in radiographic terms, and are sometimes scarcely perceptible and lack any displacement (Fig. 7.20) , or are characterized by a different angulation of the proximal metaphysis of the radius .

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Fig.7.18 Dislocation of the elbow. a L-L anterior projection of the elbow with osseous detachm ent of the trochlea and the nucleus of the epitrochlea (arrow). b-d Posterior dislocation of the elbow. Lateral projection (b) identifie s the type of dislocation and the presence of a small detachment of bone. The CT performed in plaster shows, in the saggital recon struction s (c), restoration of the articul ar relation ships following a reduction procedure, and highlight s the posterior lamellar osseous detachment of the condyle (arrow in d)

Fig.7.19 Fracture of the olecranon in a five-year-old girl. X-rays of the elbow in A-P projection (a) and L-L projection (h) show the fracture of the olecranon (arrows), which is associated with the fracture of the radial neck. cAT2-weighted saggital MRI image with suppression ofthe signal of the adipose tissue shows the compl ete extent of the fracture rima (arrow) and the presence of hemarthrosis

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Fig. 7.20 Fracture of the neck of the radius in a five-year-old boy. a The X-ray of the elbow in A-P projection highlights a small irregularity in the cortical profile of the neck of the radius (ar row) . h Ultrasound confirm s the presence of an irregularity of the osseous cortex (arrow)

Fig.7.21 Fracture of the neck of the radius in two different patient s with different degrees of angulation . a Fracture with angulation <300 associated with a fracture of the proximal ulna; b fracture with angulation >300

According to Judet and Judet 's classification, these fractures are distinguished on the basi s of the degree of ang ula tion (Fig. 7 .21) : level I: no dislocation level II: angulation <30 0 level Ill: angulation 30-60 0 level IV : angul ation >60 0 •

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Diaph yseal fraet ures of th e radius and th e ulna represent 10-45 % of ped iatr ie frae tures, and can involve one or both bon es of th e forearm; in th e case of complete fracture, the bon e fragm ent s may have varyi ng degr ees of shift, ang ulation, or superimpo sition (Fi g. 7.22) . Follow ing a trauma, generally du e to a fa ll with an outstre tched hand , the re may be other pla stic defo rm ities of the bon e of the forea rm (bowing fract ures ) involv ing both th e rad ius and th e ulna , an d possibl e association with a complete or "green stick " fracture (Fig. 7.23 ). In the case of a fract ure of onl y th e bon e of the forearm, the radiogr aphic examination should include a study of the elbow and th e wrist in order to exclude th e possibility of an atte ndant Mont egg ia or Galeazzi fracture . The Monteggia fra cture- dis loca tion (Fig . 7.24) consists of an ant erior dislo cation of th e pro ximal radius associated with a fracture of th e proximal th ird of the uln a. In pedi atric age, th e plastici ty of the bon e structures may, however, lead to dislo cation of th e proximal extre mity of the rad iu s in the abse nce of a fracture of th e ulna. In Monte ggia frac ture -dis location , th e annular ligament of th e proximal radius is lacerated or dislo cated with res pect to the radia l capitellum, and may be lodg ed in radiohumeral art iculation, thu s prevent ing, especially in the ca se of dela yed diagnosis, compl ete reduction of the radia l head; in these cases, MRI is useful (Fi g. 7.25). In cases of lat eral dislocation of the rad ial head, a nerv e lesion is re latively frequent, part icul arly a lesion of the po sterior inte rosseou s nerve, a branch of the radia l nerve .

Fig. 7.22a, b Compound fracture of the diaphysis of the radius and the ulna

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Fig.7.23 Fracture of the ulna (arrow) with angulation ofthe bone fragment s associated with plastic incurvation of the radiu s and ulna

Fig.7.24a,b Monteggia fracturedisloc ation in three -year-old boy. Lateral and anterior subluxion of the radiu s (dott ed lines) associated with a fracture of the proximal ulna (arrows)

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Fig.7.25 Dislocation of the radius in a I O-year-old girl. a X-ray image. b Tr-weighted axial MRI image shows structural irregularity of the annular ligament (arrow). To-weigh ted gradient-echo MRI images confirm the dislocation of the radius in the saggital plane (c) and the intra-articular dislocation of the annular ligament in the axial plane (arrow in d)

Fractures of the distal extremity of the forearm are the mo st frequently obse rved lesion s in ped iatric age . In relation to the extent of the traum a, gen erally cau sed by a fall with outstretched arm and hand, there may be "torus" -type fractures (Fig. 7.26a, b), "greenstick" fra ctures (Fig . 7.26c, d) , or complete fra ctures . "Torus"-type fractures of the distal met aph ysis of the radi us may be so minute that the y are not recogn ized and are ass ociated to varying degrees with fra ctures of the di stal por tion of the uln a. Fractures of the di stal met aph ysis of the forear m, espe cially of the radius, may also invol ve the physis with res ulting epiphys ea l separation; in the se case s, the di stal fragment may be disloc ated or dorsally angulated. Indeed, epiphyseal separations of the distal extremi ty of the radi us are common (Fig s. 7.27 and 7.28). Fractures of the distal ext rem ity of the radius and uln a also include Co lles ' fractures, generally cau sed by a fall with out stretched hand and with the forear m prone in dorsi flexion ; the y are ch aracterized by a po sterior disloc ation of the stump of the distal fra ct ure, which is sometimes also dislo cated laterall y on th e front plan e, accordi ng to the mechanism of the trauma (F ig. 7.29). In contrast, th e Smi th fracture (also known as th e Goyrand fracture or inverted Colles' fractur e) is char acterize d by a volar angulat ion of th e d istal frag me nt and is ca use d by direct traum as or fa lls on th e hand with

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Fig. 7.26 Incomplete distal forearm fractures. a, h "Torus"-type subperiosteal fracture of the distal metaphysis of the radius (arrows). c, d "Greenstick" fracture of the diaphysis of the radius and the ulna

Fig.7.27a,b Epiphyseal-metaphyseal avulsion ofthe radius with small metaphyseal bone detachment on the palmar side (Salter-Harris type II)

palmar flexion . Whil e in ad ults th e th reshold of ac ce ptabi lity of ang ula tion of th e fragments is ab out 10° and is conditioned by ar ti cular invol vement, the se fracture s do not involv e joints in pediat ric ca se s, and the gre ater capacity for osseous rem odel ing in children m akes a greate r ang ula tion tolerable be fo re h aving to res or t to surgery. The Gale azzi fra cture, rare in pediatric age, cons is ts of a fracture of the distal

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Fig.7.28 Distal epiphyseal-metaphysea l avulsion of the radiu s in two different patients with type I (a) and type II (b) Salter-Harris dorsal dislocation of the epiphysis

Fig. 7.29a,b Colles' fracture with dorsal dislocation of the distal bone fragments of the radius and the ulna

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diaphysis of the radius with distal dislocation of the ulna . This fracture may sometimes not be recognized, espec ially in the case of subluxation of the distal radio-ulnar art iculation; in these cases , CT, performed with scans in a neut ral position and in maximum prono sup ination , can be used for correct diagno sis of the lesion .

7.3 The Wrist and Hand The wri st is a complex region, made up of the distal epiphyses of the radius and ulna, eig ht carp al bones, metacarp al bases, and radioulnar, radioulnocarpal, med iocarpal , and carpo-metacarpal articulations . In cont rast to what happen s in the elbow, the radial volum e is bigg er than the ulnar one at the level of the wrist. The carp al bones are completely car tilaginous at birth and have an abundant car tilagi nous component until adolescence; for this reason, a trauma that in an adult would cause fracture of a carpal bone, instead cau ses a fract ure of the distal radius and/or ulna in pediatric age . The fi rst nucleus of carp al ossification is that of the capitate, already present at 2-3 months, followed , aft er abo ut a month , by that of the uncinate. Ossifi cation of the pyramidal bone begins at the age of about 2 years, of the smilunar bone at 3 years, of the scaphoid bone at 5 years, of the trapezi um and trap ezoid bones at 6 years, and the last nucleus of ossification to appe ar is that of the pisiform bone at the age of 9-10 years ; also at the level of the car pus (wrist joint), ossification always occur s at a younger age in girls. Carpal fractures, which are rare in pediatric age, are normall y associated with other fractures; as for adults, the most frequent is fracture of the scaphoid (Fig. 7.30), which is extrem ely rare prior to 7 years of age and generally observed in adolescents due to a fall or trauma to a hyperabdu cted limb. These fractures may be associated with ligament lesion s. In addition to the use of standard orthogon al projections, diagnosis of a suspected fracture of the scaphoid makes use of the projection with the hand in ulnar deviation , which allows more complete visualization of the scaphoid. Part icula r attention should be paid to the structure and profil es of the bone but also to the radio -tra nsparent fat plane adjacent to the scaphoid, in order to highlight possible dislocation , ideally to be compared with the oppo site side. Demon stration of its dislocati on may be represented by the indirect sign of a post-t raumatic hematoma. In a case where the patient compl ains of pain on palpation and function al restriction, and a para-o stal tumefac tion is evident in the X-ray, with dislocation of the adjacent fat plan e, even in the absence of X-ray signs of fracture, it is advisa ble to perform followup examin ation s, ideally MRI, in order to identi fy a conce aled fracture. If there is limited availability of equipment, it is necessary to repeat the X-ray examination after 10-15 days, following immobili zation of the limb in a plaster cast; indeed, X-ray check-ups carried out some time after the traumatic event frequentl y identify a fracture rima that was previously igno red. Simpl e fractures are treated with immobilization for 4-8 weeks. In the case of compound fractures of the scaphoid, especi ally in adolescent athletes, surgical reduction should be carried out to prevent car pa l instabil-

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Fig. 7.30 Single transverse fracture of the scaphoid in 14-year-old patient

ity and to enable a more rap id recover y. Given the unu sual arterial supply of term inal type of the bon e, a fract ure of the proximal pole of the scaphoid should, as for adults, lead to sus picion for the presence of a possibl e compl ication of avascul ar osteonecrosis; for thi s reas on, the patient should be mon ito red with X-rays and, in the case of dubious repo rt s, should also undergo an MRI exami nation . In chi ldre n, fractures of other car pal bon es arc eve n rarer ; these fra ctures mainly con cern the uncinate, the pyram idal (Fig. 7.3 I), and th e cap itate bon es. The diagnosis is frequently onl y mad e after X-ra ys carri ed out to check for other ass ociated fractures (such as distal radio-ulnar fract ures ) where the presence of thickening of car pal bon es is highli ghted in relation to th e app earan ce of osteo reparative phenom ena. As in adults, in th e case of a suspected fracture of a car pal bone which is not evi den t in th e X-ray, it may prove useful to compl ete th e diagno sis using CT. Dislocations of the wrist arc pract icall y non-existent in chi ldren . Fractur es of th e bon es in the hand are mo re freque nt than tho se of the carpus in pediatric age, and occur more frequently as a res ult of falls or being hit by a ball during vari ous sporti ng activi ties, or as a res ult of compressi on traum a; this latt er mechanis m may cau se transverse longitud inal or commi nute d fractures, espe cially in the ungual phalan x (Fig. 7.32). For the fi rst metaca rpal bon e, the X-ray should be performe d with the thumb supported dor sall y (A -P projection) and in lateral proj ect ion ; for th e other metacarpal bones, X-ray examination should be performed with P-A proj ect ion in palmar support an d with obliqu e projection, ideally with a fluoro scopic guide to ensure optimum vis ualization of the metaca rpu s; lateral proj ect ion is not useful for th e study of metacarpal bon es due to their superi mposi tion. X-ray exam ination of the fingers requir es perfect A-P and lateral projections, the latter being particularly import ant for visualization of possible dislocation of bone fragments. Fractures of the hand gene rally require immobilization for about a month , in either plaster or aluminium splints according to the site of the fracture. Surgical synthesis with thin Kirschne r wires may be nece ssary if correct reduction of the fracture is not obt ained.

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Fig.7.31a, b SmalI osseous detachmentof the right pyramidal bone in l3-year-old patient (arrow in b)

Fig.7.32a,b Longitudinalcompression fracture of the intermediary phalanx of the fourth finger with diastasis of the fragments

Some lesions of the hand are specially rel ated to specif ic sports . Violent imp act from a ball may le ad to met ac arpal -phal angeal dislocation of the thumb ( Fig . 7.33) , ch ar acterized by dor sal di slocation of the proximal ph alanx and by a marked angulation with respect to the diaphyseal axis of the met acarpus; in these lesions, the col lateral ligaments of the met ac arp al -ph al angeal articulation may be comprehensively dam aged. Detachment of a fragment of the ba se of the prox im al phalanx of the fir st fing er may frequ ent ly occur, as in the cas e of "game kee pe r's thumb", or "goalkeeper 's thumb"; this may extend to the growth cartilage, leading to a type III lesion or, more rar ely, to a typ e II Salt er-Harris les ion , cau sed by traction by part of the collateral lig am ent of the met acarpal -phalangeal articulation of the thumb.

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Fig. 7.33 Complete dislocation of the metacarpalphalangeal articulation of the first finger

Fig . 7.34a, b Type II Salter-Ha rris fracture of the base of th e f ifth metacarpus with angulation of the distal fragment

Fractures of the met acarp al bones are rarer in pedi at ric age than in adults . Frac ture of the base of the fir st me tac ar pal bon e is oft en ca use d by a traum a in hyperexten sion from a blow with a ball ; known as a Bennett's fra cture, th is is frequently a compound fracture and may require surgica l synthes is with Kirschner wi re. Fracture of the distal po rt ion of the fi fth met acarp al bone is characteristic of a traum a to a fis t ("boxer's fra cture" ). At th e level of the phalan ges, epiphyse al separation is mor e frequent, es pec ially among volley ball pla yers when form ing a "wall" to defend ag ainst smas hes at th e net (Fi g. 7.34). The mall et fi nger lesion occur s due to a mechanism of forced flexion of the distal portion of the fi nger (generally the th ird phalanx) with a stretched extensor

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tendon , wh ich is c haracteristic of the catch in baseball. In children , this type of lesion causes a type I or " Salter-Harris lesion at th e base of the distal phalanx, or even a type III lesion in ad ole sce n ts .

Suggested Readings Bishop JY (2005) Pediat ric shou lder trauma. Clin Orthop 432:41 -8 Carson S, Woolridge Dp, Colletti J, Kilgore K (2006) Pediatric upper extremity injuries. Pediatr Clin N Am 53:41-67 Cekanauskas E, Degliute R, Kalesi nskas RJ (2003) Treatment of supraco ndylar humerus fractures in childr en, accordi ng to Gartland Classification. Medicina (Kau nas) 39(4) :379-83 Chung KC, Spilson SV (2001) The frequency and epidemiology ofhand and forearm fracture s in the United States. J Hand Surg Am 26(5) :908-15 Gartland JJ (1959) Manageme nt of supracondylar fractur es of the humerus in child ren. Surg Gynecol Obstet 109:145-54 Johari AN (1999) Remode lling of forearm fracture s. J Pediatr Orthop 8:84-7 Judet H, Judet J (1974) Fracture s et orthopedie de I'enfant. Maloine, Paris, pp 31-39 Kay RM, Skagg s DL (1998) The pediat ric Monteggia fracture . Am J Orthop 27(9):606-9 Kubiak R, Slongo T (2002) Operative treatment ofclavicle fractures in children: a review of2 1 years. J Pediatr Orthop 22:736-9 Heal J, Bould M, Livingstone J et al (2007) Reproducibil ity of the Gartland classification for supracondylar humeral fractures in children . J Ortho p Surg 15( I):12-4 Heras J, Duran 0 , de la Cerda J et al (2005) Supracondylar fracture s of the humeru s in children . Clin Orthop 432:57 -64 Hovelius L, Augustini G, Fredin 0 et al (1996) Primary anterior dislocation ofthe shoulder in young patient s. J Bone Joint SurgAm 78A :1677-86 Lee SS, Maha r AT, Miesen 0 , Newton PO (2002) Displaced pediatric supracondylar humeru s fractures: Biomechanical analysis of percutaneou s pinning techniques. J Pediatr Orthop 22(4):440443 Magra M, Caine 0 , Maffulli N (2007) A review ofepidemiology ofpaediatric elbow injuries in sports. Sport s Med 37(8) :7 17-35 Murray OW, Wilson-MacDo nald J, Morscher E et al ( 1996) Bone growt h and remodeli ng after fracture. J Bone Joint Surg Br 78B:42 -50 Shim JS, Lee YS (2002) Treatment of completely displaced supracondylar fracture of the humerus in childre n by cro ss-fixation with three Kirschner wire s. J Pediatr Orthop 22( I): 12-6 Vioreanu M, Sheehan E, Glynn A et al (2007) A new type of pediatr ic injury. Pediatric s 119:12941298 Vorlat P, De Boeck H (2003) Bowing fracture s of the forearm in children : a long-term followup . Clin Orthop 4 13:233-7 Wilkes JA, Hoffer MM ( 1987) Clavicle fracture s in head-inj ured children. J Orthop Trauma 1:55-8 Wu J, Perron AD, Miller MD et al (2002) Orthopedic pitfalls in the ED: pediatric supracondylar humeru s fracture s. Am J Emerg Med 20:544-9 Wuff RN, Schmidt TL (1988) Car pal fracture s in children . J Pediatr Orthop 18:462-465

8.1 The Pelvis, Hip, and Femur The pelvi s is ring sha ped and is made up of the ili ac bone s, with the ir apophyses, the ischium with its apophyses, the pubic bones with the synchondrosis inser ted, the sacru m, and the sacroiliac art iculation s, of which two-th irds are an amph iarthrosis since an articular f ibroc artilaginous disc is inserted betw een the two j oint surfaces, and one-third a synovia l articulation. The sta bility of the pel vic ring is maint ained by the iliolumbar, sac roiliac, sacrotuberous, and sacropinous lig aments. The pel vis is highly vascular ized: the hematic contribution is mainly provided by the hypogastric vessels, or inte rna l iliac vessels, which star t clo se to th e pelvic arch; oth er important vessel s include the upp er glut eal arteri es, often damaged in posterior fractures, and the interna l obturator and pudendal vess els, often damaged in fractures of the pubic branch es. Inner vation is provided by the ner ves from the lumbar and sacral plexus, which pass through the posterior part of the pelvic ring. The site of the fracture is generally pred ictive of the type of vascular, neurological, and visceral lesion s that may be ass ociated. Th e fundam ental differenc es between th e ped iatr ic and adult pel vis include the following : the greater malleability of the bones, the capac ity of the cartilage to absorb more energy, and the gre ater elasticity of the joints; tr iradiate cartil age is present and th e periostium is thi cker : an app arent dislo cation may have a she ll of periostium and heal like a fracture . The acetabular bone has three centers of ossificat ion : the ilium, the ischium, and the pubi s; each has its own phy sis wh ich determine s circumferential growth ; at the level of the ace tabular bon e th e thr ee ce nters fuse in the trirad iat e cart ilag e whic h,

D. Barbuti (C8J) Department of Diagnostic Imaging, Pediatric Hospital "Bambino Gesu", Rome, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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on average, ossifi es between the ages of 13 and 16 years. In the course of pubert y, various centers of secondary ossification app ear; it is important to know abou t these to avoid con fusing them wit h fract ures : os acetabuli: th is for ms the ante rior ace tabular wall; it app ears at 12 years of age and fuses at 18 years acetabular epiphysis (epiphysis of the ilium): this for ms the main part of the upper acetabular wall secondary center of ossifi catio n of the ischium iliac cres t: thi s app ears at the age of 13-15 years, in the antero-l ateral portion ; it advances in a postero-medial direction and fuses at the age of 16-1 8 years, beginning inve rse ly from the postero-medial part. The Risser test, the index of skeletal maturity, is based on its app earance and ossifi cation ischiatic apophysis: th is appears at the age of 15-1 7 years and j oins at the age of 19-25 years anterior-superior iliac spi ne (ASIS) : this app ears at the age of 15 years and fuses at the age of 20-25 years anterior-inferior iliac spine (A IlS ): this app ears at the age of 13-15 years and jo ins at the age of 16-1 8 years pubic spine angle of the pub es ischiatic spine lateral wing of the sacrum.

8.1.1

Fractures of the Pelvis Frac tur es of the pelvis are not very frequ ent, representing 2.4- 7.5% of pediatric fractures ; indeed, their incid enc e is 10 tim es lower than in adults. They are due to road acciden ts (espec ially pedestrians who have been run over) in 98% of cases, a much higher percent age than in adults for whom acci dents are the cau se in 50% of cases; seri ous falls and abu se are rarer causes. In most cases they are not serious lesion s but there may be ser ious ass ociated lesion s. Apophyse al avulsion fractur es of the pel vis occur in old er children and adolesce nts, and ge nerally provide few probl ems. We shall only mak e bri ef mention of them because they are dealt with elsewhere (Chapter 3). Avulsion of the isch ial tub erosity (inse rtion of the ham string muscl es) is caused mainly by sports such as hurdling , football, gymnasti cs, fenc ing , and tenni s. Detachm ent of the ASIS (insertion of the sartoria l mu scle) occurs mainly in football, gymn astics, and fenc ing. Detachm ent of the AIlS (insertion of the rectu s femori s musc le) occurs ma inly in football, athletic s, tenn is, and sprinting. Detachm ent of the iliac crest (inse rtion of the abdom inal muscles) occur s mainly in football , gymnastics, and tenni s. The most serious lesion s derive from fractures caused by road accidents. The traum atic mech ani sms are the same as in adults. Generally, in order to cause a frac-

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ture of the pelvic ring or the acet abular bone, high- energy impacts are requ ired, which oft en caus e associa ted lesion s of a traumatic osteo-articular natur e, such as fractures of the long bones or the spine, lesions of a vascular nature (less frequ ent in adult s), urologi cal lesion s, such as injur y of the bladd er or the urethra (th e latt er mainl y in men), or neurological lesion s. In these types of trauma, a general physical examination and a local object ive examination are important in ord er to highl ight areas of bru ising , abrasi on, laceration s, ecchymosis, or hematomas of the pel viperineal region. It is important to pay parti cular atte ntion to assessing the "critica l areas", like the iliac crest, the sacro-iliac articulations, the pubic symphysis, the ASIS, and the AilS . It is necessary to examine the articular movement of the hips and it is important to perform a vascular and neurological examination as well. In the case of comp ression trauma s, even in the absence of clear fractur es, there may be damage to the trir ad iate cartil age (type V Salte r- Har ris lesions), which may result in arr ested growth , acetabular dyspla sia, subluxation of the femor al head, and dysmetria of the lower limbs. Fractures of the femoral neck are extreme ly rare, but when they occur they are associated with a high percentage of complication s. Fractures of the acetabular bone through triradiate cart ilag e only require minor- energy trauma comp ared to acetabular fractures in adult s. X-ray assessment is performed with A-P projection of the pelvi s and with inlet/outlet projections, ideally with oblique projections, although computed tomography (CT) is often nece ssary (associ ated with 3D recon structions). In the case of suspected lesions of the urinary tract , it may be important to per form a cystogr aphy using a catheter, or a urogr aphy (the latter is only nece ssary when the CT examin ation is not per formed and uses contrast agents inje cted intravenously). In the case of significant traum as, careful assessment of the whole body mu st be made to search for signs of cranial and/or spina l trauma. For unstable compound fractures of the pelvis, with lowering of the hem atocrit, it may be advisable, aft er assess ment with mult islice CT, to perfo rm an angiography and, if there are hem atom as, embol ization of the bleeding vessel. Magnetic reson ance imaging (MRI) can be used as a follow-up examin ation and may be useful for highl ight ing damage of the triradiate cart ilage or, earl ier than the X-ray, may show signs of avasc ular nec rosis of the femo ral he ad. There are various type s of classification of pelvic fractures. The Watts classification, modified by Torode and Zieg , distinguishes pelvic fracture s into the following type s: type I: avulsion fracture s type ll: fracture of the iliac wings type llI: stable fractures of the pelvic ring type IV : unstable fracture s of the pelvic ring with free bone fragmen t. The Tile classifi cation distinguishe s between the follow ing type s: type A: stable (Fig. 8. 1) type B: vertically stable, but with rotatory instability (Fig. 8.2) type C: both vertical and rotator y instabilit y (Fig. 8.3).

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Fig. 8.1 Stable Tile fracture s type A. a X-ray image of the fracture of the iliopubic branch, easily recognizable using CT (b) , where it is also possible to observe fracture of the iliac wing (c), which is not visible with X-ray. d In another patient, fracture of the iliopubic branch with slight diastasis of the pubis and the left sacroiliac (arrows). e Good situation at the check-up after 2 months

Fig. 8.2 Unstable Tile fractures. a Diastasis of the pubis, an unstable Tile lesion type B. b Postoperative check-up . c Unstable Tile lesion type B, with distasis of the pubis (arrow) and the right sacroiliac joint (black arrow). d Unstable Tile fracture type C with distasis of the pubis (black arrow) and the right sacroiliac joint (red arrow) with vertical and rotatory instability

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Fig.S.3 Five-year-old boy. Unstable Tile fracture type C with associated lesion of the urethra. a The X-ray shows a fracture of the left ilial and ischiopubic branch (arrows), associated with a fracture of the sacrum with diastasis of the right sacroiliac joint, more clearly visible with CT (b). c Lesion of the urethra at CT cystography. d Clinical appearance (d) and intra-operative view (c). f Checkup after synthesis (images kindly provided by Prof M. Oranski)

The Kane classification dist inguishes fiv e typ es: typ e I (58 %): avuls ion or fracture of a segm ent , without br eak of th e ring; there ar e gen erally no ass ociations typ e II (20%): br eak ofa singl e ring clo se to th e pubic sy m phys is or to th e sac roiliac arti culati on; th er e m ay be associat ion with abdom in al an d gen ito-urin ary lesions typ e III (7%): un stabl e fracture with doubl e bre ak of the pelvic ring . Th is includes straddle -ty pe fracture, bilateral ischio-pubic fracture, Malgaigne fracture (double ve rti cal or double un ilater al branch plu s th e ileum) ; bleeding and abdom inal and /or gen ito-urinary lesions are frequ ent typ e IV (10%) : ace ta bular fractures; th er e are freque nt associati on w ith intraabdominal or gen ito-urinar y lesions du e to th e high energy of th e trauma typ e V (5%): multipl e fra ctur es typ e" + IV or typ e III + IV. The Young and Burgess cla ssific at ion identifies fractures accord ing to th e tr aumatic m ech anism and th e di rection of th e force , distingui shing betw een th e followmg: form s cau sed by lateral compression (50 %) form s cau sed by " open book" anter oposterior compre ssion (25 %) form s cau sed by vertical shears, as happens in the case of a serious fall (5%) mixed form s (20 %) .

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The mo st widely used classification, especially in ped iatr ic context s, is the Tile classifi cat ion . Stabl e fractures include isolated fractures of unilateral or bilateral isc hiati c bran ches (Duverny frac ture ) and isolate d sacr al fractures. Unstable fractur es inc lude th e Malgaigne f racture (vertical fract ure which involves both arches) ; the soca lled "straddle " fracture, a bilateral fracture of the ilium and ischio-pubic branches, usuall y with raise d fra gment and assoc iat ed in 20 % of cases with vesic o-urethral lesion s; pelvic dislo cation with distr action of th e sacro-iliac art iculati on (normal width 1-4 mm) and the pub is (ma ximum distance between the pub ic bon es 5 mm) , oft en associat ed with genito-urinar y lesions; and th e rare "bucket handl e" fracture in which the anterior arc h is damaged on on e side and the posterio r arch is damag ed on the opposit e side. Acetabular fractures ( Fig. 8.4) occur in about 10% of traum as and are frequ ently ass ociated with abdom inal or genito-urinary lesions, since high ene rgy is required to cause them. They are class if ied into th e following types: type A: detachment of the poster ior wall with posterior luxation of th e hip type B: compound linea r fract ures ass ociated with fractures of th e pelvic rin g generall y stable type C: lin ear fractures with ins tability of the hip typ e D: med ial frac ture-dis locati ons. Particularly in type 8 fra ctures, the re is a possib ility of a lesion of the triradi ate cartilage. These le sion s may occur due to two mechanisms: direct impac t (type V Salte r-H arri s lesion) or shearing force s (type I-II Salte r-H arri s lesion) . They may be ass ociated with bone fractures with or without min imal dislo cat ion of the fragments. Possible sequelae include: progressive acetabular dy spl asia, due to thicken ing of the

Fig. 8.4 Acetabular ischio-pubic fracture in a sixteen-year-old patient. a, b X-ray; c axial CT; d coronal CT and e 3D CT provide a better view of the displacement of the fractures. f Check-up after ORIF synthesis (images kindly provided by Prof M. Oranski)

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med ial ac et abular wall and consequent su bluxa tion of th e femo ral head ; or a hypoplasi a of th e hem ip elvis due to vascular dam ag e of th e tri radiate cart ilag e which causes pr ecocious fu sion. Obviousl y, th e youn ger th e ag e of th e child, th e more ser ious th is eve nt will be. In th e case of tr aumas wh er e th er e is sus pe cte d damage of th e tr iradiate cartilag e, it is advisable to perform a prolonged follow-up exam inat io n with MRI (in th e abse nce of sy nthe ti c metal materi als) or CT, in ord er to ide nti fy s ig ns of pr ecocious ossif ication of th e cartilage its el f ( Figs. 8.5-8.7).

Fig.8.S Fracture of the sacrum and of the iliac wing and diastasis of the pubis in an eleven-yearold girl. a On x-ray, only left iliac wing fracture (black arrow) and diastasis of the pubis (red arrow) are visible. b At the CT examination, besides the fracture of the left iliac wing (white arrow) fractures of the sacrum are also visible (black arrows). c Postoperative check-up (image kindly provided by Prof M. Oranski). After one year, T2-weighted coronal MRI shows the normal appearance of the right triradiate cartilage (d), while on the left, in coronal section (e) and sagittal section (I), an ossification bridge has appeared (arrow)

Fig.8.6 Fracture of the anterior acetabular column associated with femoral diaphyseal fracture in a seven-year-old boy. a, h X-ray. c Postoperative check-up (image kindly provided by Prof M. Oranski). d CT with coronal reconstructions shows initial closure of the left triradiate cartilage (cont.7)

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Fig.8.6 (cont.) e, f The MRI shows thin hypointense areas caused by ossification of the left triradiate cartilage (I). g The X-ray performed 5 years afterwards demonstrates complete closure of the cartilage to the left (ar row)

Fig.8.7 Ten-year-old boy, a year before pelvic trauma with negative X-ray. a, b Coronal CT shows advanced ossification of the left triradiate cartilage. cAt T2-weighted coronal MRI, islands of ossification are visible in the context of the triradiate cartilage (type V Salter-Harris lesion)

8.1.2

Sacro-coccygeal Fractures These are rare and are generally caused by direct tr auma; they are usu ally tre ated with rest and painkillers . Stabl e fractur es are tr eated with immobi lization in a ca st for 4-6 weeks. Unstable fra ctur es can be treated with traction and subseque nt immobil ization, with a n ex ternal fixative or surgical synthesis (open reduction inte rn al fixat ion (ORIF)) . In general , th e fracture heal s aft er about 8 week s, wh ile in adults a longer period is neces-

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sary. The child should be kept under surv eillance for a long time after the fracture to exclude blocks to growth caus ed by prematur e ossification of the triradiate cart ilage with disturbance of the axis or dysmetri as of the limb s. Indicat ions that suggest the need for surgery include a shift in the sacro-il iac art iculations greater than I em, a diastasis of the pubis greater than 4 em, acetabular fractur es with a shift of the load-bearing area of more than 5 mm, instability of the coxo-femor al artic ulation, and fractur es of the posterior acetabular column of mor e than 50%. Traum a mechani sms , pathological pictures, and compl icat ion s vary according to skeletal matur ation. Dislo cation of the sacro-iliac art iculation s is more frequent in patient s with immature skeletons. Failure to treat unstabl e fractures can lead to pelvic asymmetri es with con sequ ences in the futur e. Surg ical treatm ent of pelvi-acetabular fractur es has few compli cat ion s when it achieves the greatest possible anatomical reduction. Complications frequently aris e from associated lesion s such as con cussion , and thoracic and visce ral injur ies. On the basis of an analysis of 120 fractur es, Reichard and coll eagu es recorded retrop eritoneal hematom a in 46 % of cases, but in only 3% of cases was surgery required to tampon the vesse l or for embolization using angiogr aphy ; transfusion s were nece ssary in 11-32 .6% of cases, more frequently in multiple rather than single frac tures (15 as oppo sed to 9) . Vesico-urethral lesion s are less frequent than in adults, about 6- 8%, and con sist of extr aperitoneal bladde r rupture in 80% of cases, with hematuri a, suprapubic pain, and hypoten sion . Diagno sis uses CT or CT cystography. Urethra l lesion s, which are more frequent in males, generally occur in fractures of the pubic branche s. They are typic ally associated with the clinical tri ad of the presence of blood in the urethral meatus, vesical disten sion , and the impo ssibil ity of urin ating . Diagno sis involves CT cystogr aphy (Fig. 8.3c). Thi s may lead to sexual dysfunctions in male s. Abdominal lesion s are found in 11-20.4% of cases of pelv ic fractures in pedi atric age, with the following percentage s: hep atic lesion s 8.4%, splenic lesion s 3.2%, urogen ital lesion s 3.2%, colon 2.1%, small bowel 1.1% (Ismail and coli) . Neurological lesion s, the cause of a cert ain degree of morbidity, are much rarer in pedi atric age than in adults (21 %). They con sist of lesions of the lumb ar root s in the case of lesion of the sacr o-i liac articulation, with deficit of the anteri or tibiali s and dorsal hypoe sthes ia of the foot in the case of lesion of L5; in the case of sacra l fracture and lesions of the S I-S2 roots there is weakne ss of the extens ion of the hip and plantar flexion , posterior hypoesth esia of the leg, the sole of the foot , and the genitals; and in the case of lesion of S2-S5, or cauda equina syndrom e, there may be hypoesthesia of the perineum , and intestinal and bladd er dysfunctions.

8.1.3

Traumatic Luxation of the Hip in Children Much less frequent than in adults, thi s may occur in children under 6 years old, due to fairly minor traum as such as a fall backw ard s while the child is bending. In the se

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cases, th e redu ction takes pla ce wit hout probl em s and without sequelae . Onl y in 15-20% of cases are these fractures assoc iat ed with acetabular fract ures or fract ures of th e femora l head, in contrast to adul ts whe re th e ass ociation occurs in more than 50% of cases . In ad ults this tak es plac e due to mo re ser ious traum as, such as sports inj uries, falls, or road acci dents . Diagnosis is performed with X-ra ys. CT may pro ve useful du e to its greater sensi tiv ity in detecting small bon e detachm ent s that may ob struct redu ction. The prognosis is link ed to the exte nt of the initi al trauma, es pec ially if associa ted with an ace tabula r fra cture of the femoral head. In children, the inci dence of avasc ular necro sis or arthrosis follow ing traumatic luxat ion is much less than in adul ts, but rap id and accurate cor rection (whic h ma y require surgery) is necessary, es pecially in the case of an assoc iat ed fracture. A delay of over 24 hours in the reduction increases the po ssibil ity of avascular necro sis. Immobilization and proscri pti on from putting weigh t on the limb are also impor tant; putting weigh t on the limb earlie r than two month s aft er th e fracture increases th e percentage of these complication s.

8.1.4 Fractures of the Femur Fractures of the femora l neck are rare ; only 1.1 % occur in pedi at ric age, but with a high percentag e of complicati ons , so they th erefo re always con stitute an emer gency. " Hip fractures in child ren are of int erest becau se of th e frequ enc y of complicat ion s rather than the frequency of frac tures " (Ca na le and Bourland). Wh ile in adults a tor sion mech anism is mo re common, in children the ca use is di rect traum a, such as a coll ision with a vehicle or a se rious fall with direct traum a of th e hip . Tran s-c ervical and ba sal fract ures are more frequ ent. There are also possibi lities of pathologi cal frac tures of the femoral neck on cystic lesion s (frequ ent in this location ) or histio cyto sis, tumors, mal ignant hemol ymph nod es, or in the case of sy ndromes with osteoporosis (imper fec t osteog enesis, ar throgryposis , etc) . The mo st common complications of these lesion s are avasc ular necro sis (13 % in the ser ies of 108 cases analyze d by Az our and coli but with aver ages in th e literatur e of up to 50%) , preco ciou s clo sur e of the ca rtilagi nous plate (12 %), var ism (8.3 %), and un successfu l con sol idation (3.7%). In ord er to explain the freq uent complications of avascular necro sis in the seque lae of these fractures, mention should be mad e of th e vasc ularization of th e fe moral head and femoral neck. It should be reme mbered that the art eri al cir cle of th e femoral head is delicate. At birth th e cartilag e of th e physis is extrasy novial. At the age of 3 years, the neck lengthen s, growing more rapidly medi all y than laterall y, and the physis becomes mai nly intracap sular. Th e med ial cir cum flex femo ral artery supplies blood to the femoral head, while th e lateral cir cumfl ex ar te ry supplies blood to the large tro chante r. This transition from the neon ate-nursling system with small multiple vessel s, to the subs equent stage with two large systems (po stero-superior and po ste roinfe rior) predi spo se s the patient for all hi s/her life to vascu lar insult of the femoral neck due to fra ctures with di spl acement.

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For diagnosis , X-ra y with A-P and lat eral proj ection (frog-leg or Dunlap) is neeess ary. CT can be useful in compound fractures for a mor e preci se measur em ent of th e dislocation for surgica l purpo ses. Fractures of the femoral neck in children follow Delbet and Chung s classifi cation (five types) : typ e I: tran s-epiphyseal fracture (12%) ( Fig. 8.8b). Thi s may be cau sed by delivery trauma which man ifes ts itself with a pseudo-paralysis of the lower limb. Diagnosis is also difficult due to the lack of ossification of the nucl eu s. In old er children, it should bc dist inguished from ac ute epiphys iolys is which generall y affect s chi ldre n over 9 years old, who oft en have endocri ne diso rders that caus e pain in the growth cartilag e and in whom the traum a that provokes th e probl em may be trivi al. Treatm ent involv es immobil ization, in the ab sence of d isloc ation, and cautious reduction and surgica l synth esis in the case of a compound frac ture . Avascular necrosis is a frequent complicat ion typ e Il: tran s-cervical or mcdio-ccr vical fractu re (Fig. 8.8d, c). This is the mo st frequent type (2 7-50%) and is oft en complicat ed by avascular necro sis (up to 50%) (Fig. 8.8g) typ e Ill: ba sal or cervi co-trochant eric fracture (Fig. 8.9) . This is th e sec ond mo st common type of fracture of the femoral neck (22-35 %) and also the second in terms of frequency of avas cular nec ro sis. It is di sloc ated in two-thirds of cas es typ e IV: inte rtrochanteric fracture, which is not very frequent (10 -19 .5%) . Complica tions are rarer; avas cula r necrosis, in particular, is possible though infrequent ( Fig. 8. 1Oa, b) typ e V: subtroc hanteric fracture (19 .5%) , wh ich many authors do not classify among the femoral ne ck fractures and th at generally is not as complicated as the other form s.

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1

C

Fig. 8.8 Pediatric femoral neck fractures. a Schematic classification according to Debelt- Chung. b Type I trans-epiphyseal fracture; c postoperative check-up. d Type II trans-cervical fracture at X-ray (arrow ); e CT clearly shows the displacement; f postoperative X-ray; g after I year, the screws were removed; there are signs of avascular osteonecrosis of the femoral head

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Fig. 8.9Type III fracture of the femoral neck. a X-ray; b postoperative check-up; c after I year, the screws were removed; irregularity of the head and neck and coxa vara is visible

Fig.8.10Type IV and V fractures of the femoral neck. a Type IV; b postoperative check-up. c Type V trochanteric fracture; d, e successful outcome with conservative treatment

Surgery is norm all y n ecessa ry an d is performed using fixat ion of one or two thi n tr ans -cer v ica l na il s or screws . One-third o f ca se s ar e ass ocia ted with pel vi c fr acture s or concussion, wh ich is wh y d iagnosi s is del ayed. Detachment of the small trochanter (i ns er ti on o f the iliopso a s muscle) is mo re rare and oc curs due to har sh contract ions aga inst resista nce o f this mu scle, l inked to

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sports activities. In general , the fracture is onl y a few mill im eters because the insertion of th e iliopsoas is prolonged in th e diaph ysis; ult rasound, and occa sion all y MRI , may be useful for det ect ing as sociated musculotendinous lesion s. Treatm ent is generally con serv ative. These fractures som etim es lead to coar se ossification. Detachment of the large trochanter (in sert ion of the medi al and small glut eal muscl es, pirifo rm muscl es, and intern al obturato r mu scles) occurs especially in chi ldren who tak e part in athl etics, as in the case of forc ed hyperabduction ("th e splits" ). Fracture of the femo ral diaph ysis may occur in young children due to ob stetric trauma or abuse; in old er childr en it may be due to a fall, sports lesion s with tors ion mech anism, or serious direct traumas. The viol enc e that is required for th is type of fracture is less than that requ ired for an adult, which also explai ns why there is less bleeding . X-ra y examination with doubl e proj ect ion is suffi cient for diagnosis. The simples t treatm ent , in very small children , is traction in ord er to achi eve good alignment and, subse quently, immobilization in a cast. It may be adv isabl e, especially in multipl e traumas, to appl y an exte rna l splint du e to th e difficulty of immobil ization using a cast. In old er childr en, generall y over 8 yea rs of age, and especially if th ey are well-built or overw eight, synthesis is oft en necess ar y, which may invol ve intramedull ary synthesis with a Kunt scher nail or elastic nail s, or with a nail-plate (Fig . 8.11) . In preparing the cast, it is important to avoid hyperextension of the knee , wh ich may lead to damage of the popliteal vessel s. Under the age of 10 years, it is acceptable to use shortening by superimposi tion of 1-2 cm (obviously gre ater the younger the ch ild) , whi ch will compensate future bone hypergrowth due to regional hyperemia linked to healing of the fracture . Over the ag e of 10 year s, shortening of 2 cm is not acceptable bec au se it would not be regained by growth. Other rare complic ations include dy smet rias, mo st frequently hypergrowth (Fig . 8. 12); and di sturbance s of the axis in valgus, in varu s, procurved or recurved. The re are other complic ations that are almost non-existent in pedi atric age, such as pseudoarthrosis, consolidation defects, and fat emb ol ism ; the latte r, though rare, should be avoided at all co sts and prevented in older children , especi ally if they have to unde rgo surgery.

Fig.8.ll Treatment of diaphyseal fractures of the femur. a Trans-skeletal traction and immobilization; b Kuntcher-type intramedullary nail; c plate with screws; d intramedullary elastic nails; e external fixative

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Fig.8.12Spiroid diaphyseal fracture of the femur. a X-ray in a plaster cast. b Hypermetria at the follow-up after I year

8.2 The Knee and Leg 8.2.1

Fractures of the Distal Epiphysis of the Femur These may derive from deli ver y trauma, in th e case of dystocic delivery, and in this case diagno sis is easier becau se th e nucleu s is alre ady ossif ied at birth, in contrast to what happ ens in th e case of deta chm ent of th e ce pha lic nucl eu s whic h is not ossif ied unt il 3- 5 month s. They arc generally type I Salt er-H arris traumas and usuall y involve posterior fract ures . The progno sis is usuall y good . They are more fre quent in childre n age d over 7 years, as a res ult of violent traumas; th ese frac tures are agg ravate d by a high percentage of shorten ing or an gular deform ity (about 40 %). It should be remembere d that distal carti lage is respon sibl e for 70% of the gr owth of the femur and 40 % of growth of the entire lower limb. In traumas in hyperextensio n, it is possible to determ ine damage to the popl iteal vasc ular ner ve sheath and, if th e symptoms do not improve afte r reduction, surgi ca l exploration is necessary. In children , sports traum as with mechan ism in valgus, which can cau se ligament lesion s in adults, can lead to ep iphyseal det achment. Sometime s only stress radiography can distingui sh ep iphyseal det achment from a ligament lesion .

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Type I Salter-Harris fractures in old er ch ildren gen er all y cau se anter ior dislocation . Ca reful as sessment of th e d istal c ircl e is nec es sary. In gen eral , bloodl ess re duction is required, pr eceded by arthro centes is in th e ca se of abundant hem arthro sis. Typ e" and III Salter-Har ris lesions occur with a valgus trauma and may not be recogni zed , inste ad being m ist ak en for ligam entous lesion. If th er e is no fracture, no reduction is requir ed . ( Fig . 8. I3a, b). Typ e IV Sa lter- Harr is lesion s (Fi g. 8. I 3c) must

Fig.8.B Fractures of the distal epiphysis of the femur through the growth plate (arrows). a Type II Salter-Harris fracture with metaphyseal triangular fragment; b type III Salter-Harris lesion with epiphyseal but not metaphyseal fracture; c type IV Salter- Harris lesion with fracture of both the metaphysis and the epiphysis

Fig.8.14 Early physeal fusion. a Shortening and partial fusion of the distal physis of the femur following a type V Salter-Harris fracture. b Multiple fracture of the femoral diaphysis with involvement of the physis, treated with synthesis in the distal part and with immobilization in a cast (c). d After a year, the comparative X-ray shows hypometria and deviation in valgus from the previous setting of the lateral part of the distal physis of the right femur

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be redu ced with anatom ical sy nthes is, whic h is oft en onl y po ssibl e with surgery, in order to avoid frequent complicat ion s (Fig . 8. 14) . The se are un stable fractures: surve illance of the young pat ient s is necessary with X-r ay check-ups on at least an annual basis until compl ete matura tion has occurred . For ty per cen t of shortenings and angulations require surgi ca l corre ction . Parcel detachm ent s in th e lat eral area of th e distal growth car tilage may repr esen t a type VI Salte r-H arri s fra cture accordi ng to Ogden, and may dam age the Ranvie r sulcus, cau sing partial growth arrest of the area concern ed, with po ssible angular deformit y, which is mor e seri ous th e younge r the child.

8.2.2

Fractures of the Patella The se are le ss frequent than in adults , representing about 1.1% of fractures. The mechanism may be direct trauma or an av ulsi on, es peci ally in the case of luxat ion or lateral sublux ation . Th e treatment is th e same as for adults and is th erefore designed to re-establ ish the artic ular sur face and exte ns or mechanism of the knee. Th e socalle d pat ellar "s leeve" fractu re re presents the typical case of frac ture of th e patell a in chi ldre n, in whic h a small blo ck of bon e is detach ed, tak ing with it a wide car tilag inous she ll. The mo st vulnerable age is between 8 and 12 years; displ acement of the cartil age of the inferior polus is po ssible and the det ached bone fragment may be very small. Treatme nt should be con servative with d ispla cem en t of less than 2 mm and the exte nsor apparatus in tact. X-ray examinat ion in double projection, supplemented with axia l projection of the patella, is generally suff ici ent for the diagno sis. In some cases it may be necessary to carr y out further examination s with CT or MR I. Differential diagno sis may involve the var iants re presented by the num erou s accesso ry nuclei of th e patella or Sinding-Larse n- Johansson disease.

8.2.3

Fractures of the Tibia Fractures of the tibia mainly affect children aged between 8 and 13 years, with trauma in extensi on and sudden intra rot ation, es peci ally cau sed by cycli ng . They are cause d by traumas of less power tha n tho se that affect adults . Th e traum at ic mechanism , whi ch in adults ca us es lesion of the anterior cru ciate ligament, cau ses thi s type of le sion . Meyer s and McK eever classify the se fra ctures into three typ es: type I: with minimal displacem ent of th e detached fragme nt from th e res t of the tibial spine. Clinically, pain is reported without significant restriction of the flexionextension artic ulation. Treatment involves arthrocentesis and a cast in hyperextension type ll: with displ ac em ent , in ge neral raised with angul ation, of one-thi rd or th e anterior half of the fragment of the spine with a "bea k-like" appearance in the

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X-r ay examination. Clinically, the patient feels pain and has function al restriction typ e 1I1: complete detachment of the spine . In type 1\ and III reduction, surgical synthes is is necessary but the prognosis is generall y good. The diagnosis is performed with X-ra y in double projection, which may be suppleme nte d by proj ect ion of th e inter condy lar tunn el. CT may sometimes be useful for precis e identi fi cation of th e posit ion of the dislocated fragm ent , or alt ern ati vely MRI may be used to as sess the state of the ant erior cru ciate ligament , which is generall y intact in th ese types of fracture. Proximal epiphyseal detachments of the tibia are rarer du e to the abse nce of ligament apparatus for inse rtion in this region. The traum a generall y occurs with a mech anism of hyperexten sion . They may rese mble ligament lesion s, and stress rad iography may be nec essar y for the diagnosis. Type III and IV Salt er-Harris lesions may require redu ct ion with bloodl ess synthes is. Fractu res of the ant erior tibial tub erosity are cau sed by a violent contra ction of th e quadric ep s mu scl e with a flexed knee. Wat son and Jon es classify thr ee types ( Fig . 8.15): typ e I: raising of the tub ercl e typ e 1I: fractured base with di spl acement typ e Ill : avulsion and raising , equ ivalent to a type III Salter-H arris fracture.

Fig.S.1S Fractures of the anterior tibial tuberosity. Schematic classification (a), X-ray (b), sagittal CT (c), and 3D CT (d) of a case of type III fracture. e Postoperative check-up

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The type I fracture may be treated with immobilizat ion in a cast, but th is oft en lead s to sy mptomatic Osgo od-Schl att er di sease. For typ es II-III , surgical reduction is generall y require d. Fractures of the proximal metaphysis of the tibi a are not freque nt; they are genera lly tre ated conservatively and hav e a good prognosis. Th e proximal fracture of the ti bia can lead to valgis m of th e knee in 15% of cases (Fig. 8.16) . The mechani sm s res pons ible for thi s complication hav e not yet been complete ly cla rified . It has been suggested that there is par tial dam ag e of the cartila ge of th e physis (typ e V Salter- Harris mechan ism) with preco ciou s asy mmetric knitting of th e lateral part , or mainl y lat eral traction for ces, or medi al inter posi tion of the soft tissues. Diaphy seal frac tures of the tibi a are frequent however. A fre quen t type of fracture is the so-calle d "toddl er 's" frac ture, wh ich affect s small child ren tak ing their fi rst falt ering steps . Th eir falls easi ly lead to d iaph yseal spir oid frac ture of the tibia with a tors ion mechan ism ( Fig. 8.17) . It is generall y a simple fractu re and eas ily treated, oft en with a delayed d iagnosis, when it is already in the healing pha se.

Fig.8 .16 Proximal metaphyseal tibial fracture without displacement. a X-ray; b appearance of valgism of the right knee after one year

Fig. 8.17 a, b "Toddler fractures" of the tibia (arrows). This is a simple spiroid fracture rima, with torsion mechanism, at times the subject of delayed diagnosis

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8.3 The Ankle and Foot 8.3.1 Lesions of the Ankle Region

The ankle is one of the mo st frequent sites of trauma and, although inj uries are often ligament lesion s, the radiologi st oft en has an important role to play in diagnosis. The distal tibia has a wide artieular surface, a large med ial mall eolu s, and a sma ller posterior mall eolu s; the astragalar dom e is a wedg e that is wider anter iorly. The dist al peron eal extre mity, or peroneal mall eolus, is linked to the tibi a by means of the ant erior and postero- inferior tibiofibular ligam ent s, by an inferior tran sverse ligament , and by a syndes mosis . The peron eal malleolus is linked to the astragalus by the ant erior and posterior talofibular ligaments and to the ca lcane us by the calcaneofibular ligament. The tibial mall eolu s is linked to the astragalus, to the calcaneus, and to the scaphoid, by mean s of the superf icial and deep parts of the delto id ligam ent. In the case of lesions, there is tumefaction and pain and it is impossible to put weight on the limb. Clinical reports are similar both in the presence of a ligament lesion and in the presence of a fracture. It is there fore essential to carry out an X-ray, which must be performed in A-P, L-L projection and with intrarotated oblique projection of about 20° ( "mortar" projection) . In rare cases, other examination s such as CT are useful for making a better spatial assessment of the position of a fragment of dislocated fracture , or alternatively ultrasound with a dynamic technique during maneuve r of the anterior "cassette" if there is a suspected lesion of the lateral ligament s (Fig. 8.18). In the case of complex ligament lesions or osteochondral lesions, MRI may be useful. Ankle lesion s may occur with four mech ani sms (Weber s classification) : supinatio n-abductio n (Webe r A) init ially cause s a lesion of the later al ligaments, the calc aneo fibul ar ligament at fir st, with transverse fractu re of the perone al malleolus; secondly, because of the imp act , the abducted astragalus causes an obl ique fracture of the tibi al malleolus supination-extrarotation (Weber B) is the most frequent mechanism, which causes four sequential lesions: lesion of the anterior-inferior tibiofibular ligaments; secondly, oblique fracture of the fibula and fracture of the posterior malleolus; and lastly, transverse fracture of the tibial malleolu s and lesion of the deltoid ligament. These may be assoc iated (in 38% of cases) with lateral lesion of the astragalar dome pronation-abduction (Weber C I) causes three sequelae of lesion s: ten sion of the profound portion of the deltoid liga ment and transver se fracture of the tibial malleolus; lesion of the tibiofibular lig ament; and lastly, obl ique fracture of the fibul ar malleolus; a distance gre ater than 5 mm between the tibi a and fibu la, in the A-P projection or the mortar suggests a lesion of the syndesmosis pronatio n-extrarotation (Weber C2) cau ses four lesion s in sequence : the fi rst two are the same as the previou s fracture of the tibi al mall eolu s and the lesion of the syndes mosis; next is obliqu e or spiroid fracture of the f ibula , on average 6-8 em above the syndesmosis; and lastly, fracture of the posterior malleolus

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ATREST

-' TALUS

~ ANTERIOR

DRAWER SIGN

Fig.8.18 Lesion of the lateral ligaments of the ankle. a Stress X-ray shows abnormal opening of the lateral jo int rima (arrow). b During maneuver of the "anterior cassette", the X-ray shows abnormal anterior translation of the astragalus with respect to the tibia. c, d Ultrasound shows the loose appearance of the ligament, which is invaginated towards the capsule in the anterior cassette (arrow). e Diagram of the procedure for dynamic ultrasound

the Maisonneu ve frac ture (Web er C3 ) is a spi roi d fract ure of th e proximal third of the f ibul a, ass oc iate d wit h a lesion of the t ib iof ibul ar sy ndes mosis and a lesion of th e inter osseous memb rane. It is ass ociated with a frac ture of the tib ial mall eolu s or a lesion of th e deep portion of the delto id ligam ent. The mechani sm is not exactly cl ear ; probabl y th e start of the sequence is fracture of the intern al mall eolu s. Diff icul t to dia gno se, it has th e same sig nifica nce that Gale azzi and Monteggia fractures have in th e upp er limb .

Fracture of the tibial p illion is often comminuted and involves the tibi al , medial , and po sterior mall eo li but without involvement of the articular surfa ce. Among the va rious type s of tibi al epiphyseal det achment, di stal ep iph yseal det achment is the mo st common in the lower lim b. It is generall y cau sed by entra pment of the foot in the spokes of a bicycle wheel or occurs as a result of a ska ting accident. The mechan ism invol ves ext ernal rot at ion with a supine foot, whi ch lea ds to type I and II Salter-H arri s lesion s, but all type s of Salter-Harr is lesion s may be encountered (F igs. 8. 19 and 8.20). Medi al fra ctures are the ones with high est ris k of deform ity; the y are often diagnosed as type I or II Sa lter-H arr is lesion s but ar e act ually type IV lesion s with th e risk of arrest of med ial growt h an d subse quent an gul ar defo rm it y (Fig. 8.2 1). For th is reason, a fractur e of the inte rnal tibial mall eolus should be accuratel y studie d ( Fig. 8.22) an d, in the case of involve me nt of the growt h carti lage, undergo surgical tre atme nt.

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Fig.S.19Type I Salter-Harris distal fracture of the tibia in an I I -year-old girl. a, b Widening of the distal growth cartilage of the tibia without dislocation of the nucleus (arrow). c, d Healthy side for compari son

Fig.S.20 Salter-Harri s fractures of the ankle. a Type I Salter-Harri s fracture of the distal epiphy sis of the tibia with nucleus positioned ju st behind ; b comparison with the healthy side. c Type II Salter-Harris fracture, detached distal epiphyseal nucleus (white arrow) and oblique vertical fracture of the metaphysis (black arrow). d Type IV Salter- Harris fracture which involves the distal metaphysis, the growth cartilage, and the epiphyseal nucleu s (arrow)

Fig.S.21 Early physeal fusion following Salter-Harris ankle fractures. a Healthy side; b results of the fracture with lesion ofthe growth cartilage: asymmetric fusion of the physis several years after a trauma, resulting in serious varism of the talocru ral joint. c Partial fusion of the growth cartilage in another patient after a trauma with negative X-ray report. d Healthy side for comparison; e after 4 years and osteotomy perform ed to correct the axis, a clear hypometria is visible. Lengthening for growth purpo ses is planned

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Tillaux frac ture is a typ e III Sa lter- Harris le sion wh ich affects th e lateral half o f the ti bi al epi p hysea l nu cl eu s in p re-adole scen ce, the phase in wh ich ce ntral c los ure o f th e carti lage begin s (Fig . 8 .23 a, b) .

Fig.8.22 Pediatric internal " malleolar" fractures. a Fracture rima of the tibial malleolus extended to the physis; axial CT scan (h) and coronal CT reconstruction (c) show how, in reality, it is a type III Salter- Harris fracture. d Apparent detachment of the tibial malleolus; coronal CT reconstruction (e) and 3D reconstruction (t) show the extension of the fracture rima to the phsyis and the distal metaphysis of the tibia: in reality, it is therefore a type IV Salter- Harris fracture

Fig. 8.23 Tillaux and triplane fractures. a X-ray of Tillaux fracture; b CT shows the level of diastasis of the detached fragment; corona l (c), sagittal (d), and 3D (e) reconstruction of the triplane fracture

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The tr iplane fracture is a typ e IV Salter-Harris lesion and also appea rs in preadol esc enc e with a mechanism of exte rna l rota tion, po stero-lateral displacem ent of the lateral portion of the epiphyseal plate, or forc ed plantar flex ion and ax ial compression of the metaph yseal region (Fig . 8.23c- e) .

8.3.2

Fracturesof the Foot At birth, th e calca ne us and th e astrag alus are th e onl y tar sal bon es to be ossified. Th e cuboid ossi fi es afte r a few months and, at the end of the fi rst yea r, so do es th e lat eral cunei form . Th e scaphoi d is the last tarsal bon e to ossify and th e tarsal nucl ei are all pres ent between 3 and 4 yea rs, but th e conformation similar to that of an adult onl y beg ins at the start of the sec ond dec ad e. At th e sta rt of development , the bon es are more oval and less multifac et ed ; the calcaneu s sti ll lac ks Bohl er 's angle and th e sinus tar si ha s not developed . Th e gr eat er elas tici ty and abundan ce of ca rti lage mak es fractures of the tarsal bon es rar er ; th ey ar e gen erally onl y caused by viol ent traumas on the road , fa lls of shar p obj ect s, or obj ect s from a great height, onto th e foot. Th e foot repres ents the ana tomica l site with the large st number of access ory bones; it is essenti al to have knowledge of all the se to avoi d mi staken diagnosi s of a parcel bone det achment (Fig. 8.24) and als o bec au se the same access ory bone may be symptomatic and th e site of a pathology.

22

0--

-

-1-- 15

Fig. 8.24 Supernumary bones that are more frequent in the foot: 1 tibiale externum; 2 scaphocuneiform; 3 intercuneiform; 4 second cuneo-metatarsal; 5 first cuneo-metatarsal; 6 intermetatarsal; 7 tarso-metatarsal; 8 os vesalium; 9 cuboideum secundarium; 10 subfibula; II talotibial; 12 supratalar; 13 supra-scaphoid; 14 sub-scaphoid; 15 trochlea of the calcaneus; 16 os trigonum; 17 subtibial bone; 18 talus accessorius; 19 sustentaculum tali; 20 talus secundarius; 21 intercalary fibula; 22 os retinaculi

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8.3.3 Fractures of the Astragalus The se are rare and are due to falls in forced dorsiflexion. Diagno sis should be carried out with X-r ay, but sometimes CT may prove necessary, for complex fractures or for a better assessment of the displacement of fragments . Four type s can be distinguished according to the Hawkins classificatio n: type 1: without or with minimal disloc ation . These are treated with reduction, if nece ssary, and immobilization type 2: posterior disloc ation of the body and area of medi al fragmentation . Reduc tion is generally obtained using surgery; it is impo rtant to re-es tablish the congruency of the subas tragalar articulation typ e 3: posterio r dislocation of the body, often with internal rotation of 90° and entr apment of the posterior tibial tendon typ e 4: with dislocation of the neck and the astraga lar-scaphoid articulation. In the abse nce of fractu re, or if displ acement is minim al, treatment should be con servative. In the case of greate r displacement or unstable reduct ion, it may be necessary to create interna l fi xation with a thin screw. A possibl e complicati on is isc hemic nec rosis, especi ally in children over 10 years old ; this generally occur s 6 months after the trauma . The "S hepherd's " fracture affects the lateral tuber cle of the posterior process and may simulate an os trigonum. Osteocondrial detachm ent of the astragalar dom e may be medial, gene rally larger in size, but less symptomatic , or lateral. Diagno sis requires an X-ray with A-P, L-L proj ections and obliqu e int rarotated projec tion (mortar projection). MRI is useful in these forms of fracture, for assessing cartilage damage and the pain of the adjoining osseou s spongi osa. Treatment should generally be conse rvative but surge ry may be necessary if there is no res ponse within 6 mo nths.

8.3.4

Fractures of the Calcaneus These are more frequent, linked to seri ous falls (e.g. from a tree) and, because of the violence of the impact, may be associated with fract ures of the rach is and/or the other foot. The main types of frac ture of the calcane us are the followi ng: fractures of the tuberos ity, of the sustentac ulum tal i, and of the body, without involvement of the subastraga lar region, and fract ures caused by compressi on of the body, involving the subastragalar region. There may be "t oddler's" frac tures in sma ll children under 3 years old, due to modest trauma, and these are difficult to diagnose. In older children, stress fractur es are possible, thou gh rare. Patholo gical fract ures are possi ble on preexisting focal osseou s lesions of a lytic type or in the case of osteopen ia-rel ated diseases, such as imperfect osteogene sis or in cer ebropathic children. Wiley's classification is the most commonl y applied in pediatrics. It distinguishes two types :

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Fig.8.25 Calcanear fracture with thalamic depression in a seven-year-old boy. a X-ray; h, c CT shows more clearly the displacement; d follow-up after synthesis with screws and cast

typ e I : without invol vement of the subastraga lar articul ation ; it includ es A, a beak; B, vert ical; C, hor izontal ; D, avuls ion of the medial rim ; E, fracture of the ant erior process typ e 2: with involve ment of the subastragalar articulation ; it includes A, simpl e; B, "tongue" fracture with op ening up to the calc an eal apophysis; C, centrolateral with displ acement; D, of the sustenta culum tali (Fig . 8.25); E, comminuted. In non-compound fractures, treatment involves immobilization with the foot raised, which is suff icient; heal ing take s place in 6 week s, but with proh ibition of weight-bearing on the limb for a further 4-6 week s. In compound fractures, especi ally in adolescents and if accompa nied by depression of Bohler 's angle, surgical osteo synthesis is necessary.

8.3.5

Fracture of the Scaphoid This is a rare and generall y not a compound fracture. "Toddler's" fracture of the cubo id may occur in children und er 3 year s old du e to relatively mod est traum a, and is difficult to diagnose.

8.3.6

Lisfranc Fracture This is a fracture with luxation of th e midfoot, first described by Dr Lisfr anc , a doctor who served in Napoleon Bonaparte 's army, in a horseman who fell from his hor se with his foot trapped in the stirrups. It may occur du e to tors ion of th e foot in a hol e or in sports injuries , and may app ear in young people as a navicul ar- astr agal ar luxation without fracture (Fig. 8.26) . X-ra y exa mi nation in the dorso-plantar, lateral , and obliqu e proj ect ions shows lateral luxat ion of metatars als II -V, which dev iat e from metatar sal I with possibl e fractures of the cunei forms or th e metatar sal bases .

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Fig.8.26Scapho-talar dislocationin a l3-year-old boy due to a fall during a basketball match. a, b First X-ray. c Follow-up after reduction Treatme nt of th is fr acture, if the di slo cat ion is le ss th an 2 mm , involves imm obi lization and rest for 6 weeks. In the case of greater di spl acement, int ern al surg ica l fi xa tion is nec essary.

8.3.7

Fractures of the Metatarsals and Phalanges Thes e are linked to a di rec t tra uma (Fig . 8.27) or a we igh t fall ing onto the foo t. Marching f racture of the second met atar sal is one of the mo st freq uent str ess fractur es ; in th e foot, th is m ay also occur in th e cuboid and the ca lcaneus . Fra ct ur e of the b ase of the fi fth metatarsal (Jones f racture) occurs due to a trauma in inversion of th e for efoot, often ca us ed by avuls ion of the sh ort fi bu la, and m ay be ass ociated with a le sion of the lat eral ligaments of the ank le . In th ese event s, it is necessary to make a di fferenti al di agnosis w ith the access ory nucleus of the base of the fift h metatarsal , a frequent variant (Fig . 8.28). Be side s cl in ical tre atment and loc al tumefacti on, it is necessar y to take ac count of the fact th at the avu lsi on fract ur e is of a tr an sverse type , while the nucleu s is placed longitudinall y.

Fig.8.27Type 1\ Salter- Harris fracture of the base of the distal phalanx of the big toe during karate training in a nine-year-old boy. One can observe the fracture of the distal epiphysis of the proximal phalanges 2nd and 3rd ray

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Fig.8 .28 Fracture of the V metatarsal base in comparison with secondary nucleus of growth . a Fracture of t he base of t he fift h metatarsal. The fracture has a transverse course (red ar row) and is associat ed with tumefaction of the soft tissues (white arrow) ; b the seco ndary nuc leus of growth of the base of the fifth metatarsal has a longitudin al course (arrow)

Suggested Readings Azour EM, Karamitsos C, Reed MH et al (1993) Types and comp lications of femora l neck fractures in children. Pediatr Radiol 23:4 15-420 Canale ST, Bourland WL ( 1977) Fracture of the neck and intertrocanteric region of the femur in chil dren. J Bone Joint Surg 59:43 1-443 Chia JP, Holland AJ, Little D, Cass DT (2004) Pelvic fractures and associated injuries in childre n. J Trauma 56(1):83-88 Connolly JK ( 1988) Fratture e lussazioni. Verduci editore, Roma Heeg M, Visser JD, Oostvoge l HJM (1988) Inju ries ofthe aceta bular triradiate carti lage and sacro iliac j oint. J Bone Joint Surg Br 1:34-37 Holden CP, Holman J, Herman MJ (2007) Pediatric pelvic fractures. J Am Acad Orthop Surg 15(3):172- 177 Ismail N, Bellemare JF, Mollitt DL et al (1996) Death from pelvic fracture : children are different. J Pediatr Surg 31( I):82-85 Letourne l E, Judet R, Elson R ( 1981) Fractures of the acetabulum . Springer-Verlag, New York Ogden JA (1990) Skeletal injury in the child. WB Saunders Company, Philadelphia Reichard SA, Helikson MA, Shorter N ( 1980) Pelvic fractures in childre n - review of 120 patients with a new look at general manageme nt. J Pediatr Surg 15(6):727-34 Salter RB ( 1974) Injuries of the ankle in children. Orthop Clin North Am 5(1) :147-52 Schlickewei W, Keck T (2005) Pelvic and acetabular fractures in childhood. Injury 36 [Suppl 1]:57-63 Spiguel L, Glynn L, Liu D, Statter M (2006) Pediatr ic pelvic fract ures: a marker for injury severity. Am Surg 72(6) :481 -4 Swischuk LE (1994) Emergency imag ing of the acute ly ill or inj ured child, 3th edition . Williams & Wilkins, Baltimore Tile M (1995) Fractures ofthe pelvis and acetab ulum, 2nd editio n. Williams & Wilkins, Baltimore, pp 4 1-52

9.1 Introduction It is rar e to detect a traum atic bon y le sion in a very sma ll child. In the f irs t two or three years of life, children are constantly chec ked by a re sponsible adult, and the incidence of skeleta l traum a is low. Instances of traum a incl ude: ob stetri c pseudo-paral ysis " bir th fractures " acci dents that often occur in the nursin g infant , such as fall s from the changi ng table, which are oft en the cau se of cra nial fract ure events th at also involve the person caring for the child, such as accidenta l fall s or, in particular, ro ad accidents non- accidental lesion s, which incl ude the condition of "ba ttered child syndrome" "toddler's fracture s" , or fracture s that occur when the child is walking with an unc ertain gait.

9.2

Obstetric Pseudo-paralysis Ob stetric pseudo-paralysis includes traumati c lesion s of the ca rtilage of conj ugation of the long bones of the limb s, with chondro-epiphyse al separation, that is Sa lter- Harr is type I fractures, which are cause d by the maneuvers of delivery and birth.

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Fig.9.1 Anterior longitudinal ultrasound scan of the hip. a Normal position of a non-ossified femoral epiphysis (arrows); b epiphyseal displacement (Salter- Harris type I fracture)

The diagno stic value of ultr asonography in incomplete separations (Fig. 9. 1) is particul arly impor tant in the uppe r limb, where the absence of signs of ossifi cat ion of the gr owth nucl ei of the humerus mean that x-r ay exam ination is of limited value, and may only give positive signs of fractu re after a week, when signs of calci fication of the reparative callu s appear. Proximal chondro-epiphyseal separation of the humerus is the most frequent form of obstetric pseudo-paralysis, and is likel y to occur in any birth where it is necessary to subje ct the limb to an axial tract ion of 60 kg or mor e. Distal chon dro-epiphyseal separation of the humerus, on the other hand, is very rare, and can easil y be confused clin ically with a paralysis of the brachi al plexu s and, at x-r ay examin ation , with a disloc ation of the elbow. The lesion is the result of a violent movement of hyper extension of the elbow. Manu al breech extraction can be linked with the appeara nce of a proximal chondroepiphyse al separation of the (incomplete or complete) f emur, with or without periostal laceration. The knee is rar ely involved during obstet ric maneuvers, with dista l chondroepiphyseal sepa ration ofthe fe mur; all the described cases refer to shoulder or breech present ations.

9.3 "Birth Fractures" " Birth fractu res" frequently occu r in cases of breech present ation, shoulder dystoci a, macro somi a, or rapid deli ver y bec ause of fetal distre ss. They can also occur during cesa rian section.

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The clavi cle is the bon e mo st affect ed, usual1y th e middle th ird (Fig 9.2). Fractur es of th e distal clavicl e are occa sional described but are more freque nt in ca ses of non-acciden tal trauma. Birth fracture of the clavicl e may be complete or incompl et e, and is oft en an oc cas ion al find ing dur ing a ch est rad iograph y perfo rm ed for oth er reasons (Fig. 9.3) . Ultrasonography can replace radiogra phy, avoiding ionizing radiation (Fig. 9.4). Th e differential diagnosis includes conge ni tal peudoarthritis and non-acc idental frac ture but birth fracture is always ch ara cterized by an ex ube rant cal1us. In al1 birth frac tures the cal1us form s ea rly and is volum inous.

Fig. 9.2 Newborn (11 days of age) birth fracture. Radiograph of the clavicle shows an exuberant callus

Fig. 9.3 Newborn. Chest radiography. Occasional finding of birth fracture by the right clavicle

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9

_~~_,.~ .-;iT'~ ~ -~ ,;.~:.?"_ -.~~/;::;;i-~.'O' -c::.. ....... ,~""'"'-. -..

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Fig.9.4 Newbo rn . Ultras onography of the clavicle. a Birth frac ture (arrows) ; b exuberant callus (ar rows)

Th e rep air proce sse s are cl earl y vis ible radiographi call y 7- 12 da ys after birth. A fract ure without si g ns of bone re pair in a chi ld o ld er than II days of a ge is sus pi cious o f non-accid ental injury. Salter -H ar ri s typ e I and II fr actures arc characteristi c of femur an d hum erus birth fractures . Sometimes there ar e multiple rib fr acture s th at can re sult in severe re spiratory sym ptoms.

Suggested Readings Behrman RE, Kliegman RM, Jenson HB, eds. (2000 ) Nelson textbook of paediatrics 16th ed, Philadelphia, Pa: Saunders; 455-456 Glass RBJ, Fernbach SK, Norton KI et al (2004) The Infant Skull: A Vault of Information. Radiographi es March 24:507-522; doi: I 0.1 I48/rg.242035 I 05 Radkowski MA, Merten OF, Leonida JC (1983) The abused child: Criteria for the radiologic diagnosis. Radiographies June 3:262-297

10.1

Introduction

The incl usive age between 10 month s and 3 years is denom inated "toddler age", because of th e ty pical hopp ing and uncertain mann er in which th e child wal ks, moving autonomously without the direct contr ol of an adult. In th is period, speci fic fractures of th e inferior extre m ities arc common, as a result of fall s that submit th e bon es of th e limb to to rsion al , hyperexten sion , or imp act traum a.

10.2

The Concept of Toddlers' Fractures The original de scription of "toddler's fracture" (Dunbar et aI., 1964) concerned a part icul ar type of spiroid fra cture of the tibi a, which is difficult to detect on the basis of a medical hi story comparing a clinical and phy sic al evalu ation with the event s leading to the pre sentation . An objective picture th at is almost exclusively rep resented by a moderate limp or re fusal to walk often occurs in the pre sence of other bone le sion s of the infe rio r limb , wh ich can be included in a wider con cept of "toddlers' fractures" and include part ial fra ctures from imp act (cuboid and calc aneus) and hype rextension fra ctures ("buckle" fractures of the base of the fir st met atarsal prox imal tibi a, or di stal segment of the fi bula and tibi a).

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10.3 Imaging Radiographic chara cterization of these fr ictur es is not oft en easy, especially in the acute phase immed iately after the traum a, although lat er on (aft er about a week) , the appearance of phenom ena indicating hea ing, oft en exuberant, facilit ate definition of the frac ture . However, thi s may present probl ems with different ial diagno sis, particularly in the case of non-a ccid ental inj uries, and lead to delays in diagnosis and treatm ent becau se of the non -spec ific ity I ,f the medical histor y. The presentation is dom inat ed by symptoms of pain , spon taneous or provok ed, that is invariabl y referred to the ank le region. This is fund unentally sign if icant and is at the root of the probl em of clin ical identification of 1he possibl e locat ion of the fra ctur e. Nonspecifi c radiography of the ankle j oi nt wi II not necessarily give a corr ect diagno sis unl ess the projections are specifi cally ada otcd to the type and location of the lesion. It is ad visable to put in plac e a protoco l of cli nical evaluation to adequately dir ect the radiog raphi c investigation, taking account of a series of fundam ental evaluation s: submitti ng the limb to an accurate inspect ion, looking for pain ful swellings of the soft tissue s, which are gene rally pre sent in fractures of the base of the first met atarsal gr asping the knee and ank le, imp arting a tor sion al force on the leg to indic ate the presence of a spiroid fracture of the tib ia submitti ng the knee to hype rextension to assess any suspicion of a "buck le" fracture of the proximal tibi a compressing the ankle, tarsus at the cuboid, under the first met atarsal and the heel , in an attempt to evoke a specific pain ful reaction that is characte ristic of "toddlers' frac tures" . The clinical evalu ation is fundamenta l, not only to ident ify the area of radiogr aphic intere st but also to address the choice of technique for the investig ation . Certai n specific radiogr aph s are essent ial to underline part icul ar lesion s, such as tang ent ial projections for imp act fra ctures of the heel. Spiroid fra cture of the tibia is generally represented by a thin hyperlucent line (Fig. 10.1), which may extend to include the whole skeletal segment but is always visible at the level of the distal thi rd of the bone . Late radiogr aph s of "toddler's fracture" can determine the onset of a violent perioste al reaction (Fig. 10.2) that can cause problems of differenti al diagno sis with both non- accidental injuries and infl amm atory pathologies such as osteiti s and osteomyeliti s, as well as Ewing's sar coma and leukem ia. "Buckle fractures" are characterized in the acute phase by a light imp rint of the skeletal pro file from dep ression of the cort ical border on the vent ral side of the bone sufferi ng con sequ ent hyperextension traum a (Fig. 10.3) . A radial line of fracture becom es evident later, on the oppo site side, becau se of the low density of the fra cture and its margins, with the appearance of porous canc ellou s bon e adj acent to the widespread perio steal reaction.

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Fig. 10.1 The radiograph shows a spiroid fract ure of the tibia (ar row)

Fig. 10.3 Buckle fracture of the distal tibia (arrow) . The oblique radiograp h shows a

light imprint of the skeletal profi le from depression of the cortic al border

Fig. 10.2 Toddler's fract ure of the tibia. The radiograp h, performed 19 days after injury, showed a diffu se diaphyseal perio stea l reaction

Fig. 10.4 Toddler's fracture of the cuboid. The area of the trauma looks slightly flattened and sclerotic (arrows)

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In contrast , "toddler's f ractu re cuboid" , is ins te ad re pre se nte d by a subc hon dral fracture of th e dorsal slope of th e cuboid, wh ich is difficult to identify and appe ars as a light depress ion of th e profil e; at a lat er stage, a condition of marg in al scle rosis in th e imm ed iat e area of th e trauma is al so appa re nt. Th is is a subc ort ical fra cture resulting from calcaneal-c ubo ida l impact , wh ich will heal spont ane ous ly and so do es not requ ire specific dia gnost ic investigation s. Th e use of spec ific ima g ing techniques such as sc intig raph y or magn etic reson ance ima g ing is reserved for ex ce pti ona l cases (Fig. IDA) . It is int eresting to note that ost eochondrosis affects not th e cuboi d, and th e area of ost eitic processes and osteo arthrit is is lo cat ed at th e ventral surface at th e joint with th e meta tar sal base .

Suggested Readings Dunbar JS, Owen HF, Nogrady MB et al (1964) Obscure tibial fracture of infants - the toddler's fracture. J Can Assoc Radiol 15:136-144 John SO, Moorthy CS, Swischuk LE (1997) Expanding the concept of the toddler's fracture. Radio-Graphics 17:367-376 Swischuk LE, John SO, Tschoepe EJ (1999) Upper tibial hyperextension fractures in infants: another occult toddler's fracture. Pediatr Radiol 29:6-9

11.1 Introduction First of all a fir st fundamental di stinction mu st be made between lesions resulting from a single act of phy sical violence and tho se occurring as a result of phy sical maltreatment. We are better able to clarify the di stinction using the definitions propo sed by the Itali an Penal Code: physical violence (art.572 c.p): "harm ful action that immediately produces an acute physical effect and requires an urgent int erv ention" physical maltreatment: "r epeated behav ior lead ing to suffering in the victim, and resulting in a relation ship with th e person re spons ible that is characterized by pain". The definition of phy sical violence also includes the condition termed "shaken baby " syndrome, characteri zed by serious lesion s of the central nervous system induced by a maneuver of violent sha king and abrupt decelerat ion cau sed by imp act of the bod y of the baby on a soft surface such as a mattr ess or pillow.

11.2 The "Battered Child": Imag ing In 1860, Ambroi se Tard ieu de scribed a series of traum atic lesion s in very small ch ildren from an anatomical-pathologica l and phy sic ian-legal point of view; the se lesion s had common characteri stic s, resulting from phy sical maltreatment, and were

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often accompanied by signs of lack of material care . Fifty-five per cent of the cases describ ed involved subjects younger than 5 years and 30% of these were in children aged under one year. In over 70% of cases, the lesion s were intentionally caused by the parents (by both parent s in about 35%), and rapid improvement was obser ved after removal of the child from the hou sehold . In 1946, Caffey not iced in children of a very young age the frequent associati on of chroni c subdural hematomas with traumatic lesion s of the long bones of the limb s that had been ignored or were not adequate ly explaine d by their parents or the person res ponsible for their care. Kemp e, in 1962, propo sed definition s for these cases , which are widely used today: "batte red child syndrome" otherwise known as "sy ndrome of Ambroise Tardieu", or "sy ndrome of Caffey-S ilverman" . A definition that perhaps mor e closely reflects the real ity of the situation is that given by the acronym PITS ("p arent- infant trauma syndrome"), while the anatomical-pathologica l product of th is specific form of physical malt reatm ent is mor e correctly defined by the term " non-accidental traum atic lesions". The clinical presentation is dominated by mult iple and compl ex man ifestation s of signs that are obser ved in addition to the skeletal lesions: brui sing, scratches, burn s, scorching from cigarette s, and other cutaneou s lesions; contu sive defo rmit ies such as the so-called "boxer nose" a general state of lack of physical care lesions of the nervou s system lesions of the thoracic and abdominal organs. Skelet al damage cannot always be confirmed, but when it can , extreme care must be exercised in reaching a diagno sis. In only 50% of cases doe s the subj ect present for clin ical obser vation in relation to the pre sence of a fractu re, but the suspici on of physical maltre atment is nevertheless indic ated by potenti ally non- accident al skeletal inj ury. For child-protection reasons, in cases where reliable clini cal-phy sical information is not avai lable, the use of bone scintigraphy can be ju stified, balancing the panoramic view it offers agai nst the dose of ionizing radiation. Although very sensitive, scintigra phy is neverthele ss non- spec ific and provides little detail of morphology, which, if damage is confirmed, can be obt ained by conventional radiology directed at the area(s) of clinical inte rest. Recogn ition of met aphy seal frac tures is compl icated by the intense uptake of radioactive indicator by the actively grow ing metaphysis; however, the se represent the most typi cal type of injur y. It is reasonable to ass ume that if there is suspicion of physical maltre atment in subj ects aged under two years, a radiograph ic examin ation of the whole skeleton is always necessary. Between two and five years of age, the choice to assess the whole skeleton by x-ray depend s on the indiv idual case, while in children aged over f ive years, whole-body x-ray is only used in exce ptional circum stanc es There are sever al reasons for this:

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one-th ird of subj ects are aged less than one year metaph yseal lesion s, which are often difficult to diagno se, usually involve the youngest children in infant s and toddl ers, lesions are oft en not readily apparent and can be underestimated or undetected by parents and relatives children aged fi ve years can effectively defend themselves and can give deta iled descriptions of lesion s, as well as being able to accurately point to the center of pain. Limiting the dose of ionization is a major con sideration , and can be achieved by util izat ion of investigative proc edur es that maxim ize the rad iograph ic field of view. It is recomm end ed to use large-fo rmat or wide-proj ection radiog raph s (labeled "b abygrarn s") , becau se tho se of lower quality are of littl e use for diagno stic purpo ses; further more, in mo st cases, becau se of the inadequacy of the find ings, they res ult in an unjustifi ed increase in rad iation dose. A high-quality image is esse ntia l in these cases, to avoid false-negative res ults, which are extre mely dang erou s as they may prevent removal of the child from the fam ily, thu s promoting the recurre nce of crime with potentially tragic con sequ ences. The f irst-level imaging is therefor e represented by conventiona l radiog raphy, supplemented later by additional methods such as ultr asonography to assess the soft tissues and mon itor developmental processes in the form ation of bony callu s or to study cert ain type s of fracture s such as tho se of the epiphy ses. Magnet ic resonan ce imaging (MRl) investigations constitute second-level imaging for the evaluation of articulations and soft tissues, and to search for poss ible hidden frac tures (not identifiable with convent ional radiology alone, although they may be suspected on the basis of the scintigra phy), or, in particular, for mon itor ing and evaluating possible disabling sequelae. Complex fracture s in particul ar location s (such as the face and skull base) instead requ ire the use of computerized tomog raphy. Finally, the importance of post-mo rtem imaging must not be overlooked, parti cularly conventional radiogra phy of the whole skeleton. The fir st fundamental task, represented by the detection of lesions, requires the radiologist to address a seri es of issues that are basic to corre ct organization of the case : identi fic ation of fractures at sites that are considered to be character istic search for particul ar anatomical-radiological characteri stic s in fractures that are othe rwi se non- specific assessing the date of occurrence of each individua l lesion that is verified description of the possible rel ationship between characteri stic s of the lesion and the type of prec ipitating traumatic event pred ictive assessment of possible disabling con sequences differential diagno ses. This is, of course , a complex task, and one that the rad iologist can only achi eve by full collaborat ion with all oth er pro fessional s involve d: th e clini cal patho logist/anatomi st, the psychiatr ist, the coron er, and the j udge .

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11.3 Fractures in Specific Anatomical Sites In ver y small ch ild re n, some typ es of fracture a re highl y unlik el y to be accidental , th is includes fract ures of th e: shoulde r blade and acromion distal th ird of th e clavicl e branches of th e ilium , is chi um, an d pubis (Fig. 11.1 a) femoral ne ck (Fig . Il.l b) tubul ar bones of the super ior and inferior extremities vertebra l bodies (Fig . 11.2) .

Fig.11.1 a Fracture of the branches of the ischium and pubis (arrow). b Femoral neck fracture

Fig. 11.2 Newborn. Fracture of a lumbar vertebral body (arrows)

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Corre ct visualiz ation and inte rpre tation of th ese lesion s it is esse ntial to address th e suspici ons raised when th e type of impro bable justification proposed by the relativ es is highl y indi cat ive of a cond ition of physical maltreatm ent.

11.4

Fractures in Non-specific Anatomical Sites,with Particular X-ray Characteristics for Dating of Fractures

A diaphyseal fracture , generally of the humerus or femur, is often present, but has no specific characteristics as it is relatively common in children of this age (for example injury from the bars of a cot). This type offracture is, however, also frequent in cases of maltreatment, while evidence of repair processes is also indicative of a lack of care (Fig. 11 .3). It should be noted that diaphy seal fractu re, along with crani al traum a is one of the mo st frequent reas ons for ho spit al ization of young ch ildren , and is often acc ompanied by other more specif ic lesion s, often from a different time , and not always declared or adequately justi f ied by the family. Mult iple lesion s of different date , inco rr ectly interp reted on th e basis and source of explanat ions of acc idental injury, form th e basis of most ca ses of suspected abuse . Th e dating of the lesion th erefore ass umes a fundamental importance and is esse nt ially based on th e findings of a relatively typical pattern of evolut ion: bevel ing of th e bord ers afte r a week increase in den sity beginning from two weeks app ea ranc e of new periosteal reaction spec ifically with in four week s initi al signs of ossification aft er around one mon th remod eli ng of the traumatic area beginn ing from about ten week s.

Fig.11.3 Untreated and not recent fracture of the humeral diaphysis (arrows). Exuberant and irregularcallus. Angled and overlapping fragments

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Salt er-H arr is fractures (lesion s of the grow th plat e with epiphysea l separation) of appendic ular bon es are oft en found , es peci ally in infants; these are generally Salte r- Har ris type I (without direct involv ement of th e metaph yseal or epiphyseal compone nt) . This type of lesion , which has a pr eferen ce for the hum erus and the pro ximal femur is, nevertheless, also non- specific and is commonly present in accidental fo rm, as "birth fracture" or as a result of man euv ers of incorre ct nur sing. The separation, which in th e initi al stages is a short distance from th e traum a, is clinic ally suspected, but is diff icult to prove without radiographic evide nce of ossif ication at the epiphyse al growth nucleu s. Under these cond ition s, ultrasonographic exa mi nation has a cru cial rol e, facil itati ng a safe and tim ely diagnosis (Fig. 11.4) . In thi s particul ar type of fracture, perio steal and reparative calcium depo sition only lead to a signif icant radiogr aph fi nding 10-14 days after the tim e of inju ry. In a suspici ous contex t, a find ing of an exaggerate d osteocalc ification rea ct ion can be indicative of neglect. Frac tur es of the skull are also very frequent in these ca ses, but are of littl e use in confi rma tion of sus pecte d "batte red child " as they lack specifi city. Cranial fractur es are very common in all chi ldren aged und er two yea rs, but , in the absence of neurolog ical con sequences, are frequentl y und erestimated. Comparison of chroni c subdura l hem atomas, in ass ocia tion with recent int racranial bleeding and bon y lesion s (even if from a different date) gives significant info rm ation in the suspicion of "Caffey- Silverman" syndrome.

Fig.11.4 a Ultrasonographyof the distal femoral metaphysis in infants with chondro-epiphyseal separation (Salter-Harris type 1\ fracture). b Corresponding diagram

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The cond ition of "s haken baby" , the result of a single violent action, is not includ ed in this type of investigation, although it ca n fit into a broader contex t of physical abuse . Corre ct dat ing of a linear fracture of the skull is undert aken meticulously; the hyperlucent line identifi ed by convent ional rad iog raph y may still be identifiable 6 or 12 months after the traum atic event, although the oth er radiog raphic signs are nonspecific: pseudo-diastasis of the fracture, by rea bsorption of the edges exaggera tion of the bord ers in relation to the phenom enon of ossificat ion of the callu s prog ressive grad ient of hyperluc enc y. The use of mor e sophistica ted methods such as MRI add s littl e to the possibility of dat ing this type of frac ture .

11.5 Fractures with Particular Radiographic Characteristics Some form s of traumatic lesion of the child skeleton assum e a funda mental importanc e in the rad iog raph ic diagnosis of physical maltr eatm ent , and they are always sought and car efull y evaluated since they are very useful for defining a presumed link betw een the type of lesion and a definite cause . Metaphyse al fragmenta tion, cort ical hypero stosis, and "cup'l-type deformation of the metaph ysis are highl y specif ic result s, particularly in childr en who are younge r than 3 years of age. Thi s generall y con cern s lesion s that do not have broad clin ical-ph ysical man ifestat ion s, and as such they are often not recognize d by the parents or care rs, who , when con front ed with their presence, either propo se improbabl e explanations or confess what happ ened. The ca use is generall y a con cussion or compression trauma, which is exacerbated by the insti nctive reaction of the child facilitated by the particul ar anatomi cal conform ation of the child's perio steum . In childre n, and particularly in infants, the periostium covers the metaph ysis and is intimately connect ed to the physis where it merges with the perichondrium. Thi s favors verif ication of specific metaph yseal fractures, such as the so-called "corne r lesion s" (Fig. 11 .5) and "bucket-handle" fractures (Fig . 11.6). These traum atic metaph yseal fragmentations can be dated with some precision , because, as they are already evide nt immediately after the trauma, they follow a specifi c patt ern of repa ir charact erized by progr essive cortical perio steal reaction which , in less than 20 days, lead s to fusion of the fragme nts with subsequent coalescence (Fig. 11.7). The extent and repetitiveness of the traum a, as well as the abs ence of suitable care , facil itate the persistence of gro ss rep arative features and the appea rance of a met aphyseal cupping (Fig. 11.8).

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Fig.11.S Radiograph ofthe knee. Newborn with metaphyseal lesion s by non-accidental trauma. Metaphyseal "corner lesions" (arrow). Femora l and tibial met aphyseal fragmentation

Fig. 11 .7 Battered chi ld . Radiograph of the tibia performed 13 days after the traum a shows metap hyseal fragmentation sequelae with progre ssive coa lescing (arrows)

Fig.11.6 Radiograph of the knee. Newborn with metaphy seal lesions by non-accidental trauma. Femora l and tibi al metaphyseal "bucket-handle" fracture s (arrows)

Fig.11 .8 Radiograph ofthe tibia shows cupping deformation of the tibial distal metaphysi s (arrows)

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Deformation of th e metaph ysis develops slowly over weeks and months, and favors th e persistence of perman ent and disabl ing side effec ts such as bend ing and asymm etry of th e limb s. Th e perio steum of a child is characteri zed by stong osteog enic activity in th e cortex and an exuberant germ ination layer, whos e fun ction is to ass ure rapid axial growth of the skeleta l segment. It is not infrequent , especially in premature subje cts, and particul arly dur ing the second and third month of life, to see radiog raph ic ev ide nce of so-ca lled "pe rioste al lin es" at the level of th e diaph ysis of the femur, hum eru s, and tibia , which are the physiological express ion of poor adhe rence and exube rance of perio steal proliferation; these tend to progressively coalesce with th e und erlying cortical sur fac e and mu st not be con fus ed with pathologi cal man ifestation s of perio steum. A perio steum with these anatomical-function al characte ristics is par ticularly fragil e and ea sily detach es. Dissect ion of the hypervascul arized osteogen ic layer of cortical bon e from the surface of the cortical bon e results in freq uent subpe riosteal hemorrhag es. This detachm ent and subpe rioste al hemo rrh age follow ed by agg ressive osteogen esis can , with re peated episodes of traum a, lead to establis hment of form s of extern al cortical hyperosto sis, which are sometimes so marked they form large calci fied diaph yseal "sleeves" ( Fig. 11.9) . The form ation of co arse and voluminou s "sleeves" take s severa l week s. Rib fra ctures (Fig. 11.10) , which are very frequent , should be ana lyzed with special attention to sea rching for highly specif ic aspects : multipl icity bilate rality location different dating .

Fig. 11 .9 "Battered child syndrome". Widespread periosteal newbone depos itio n a round th e femoral diaphysis (black arrows) and metaphyseal irregularit y and fragmentation of the distal metaphysis (w hite arrows)

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Fig.11.10 Chest x-rays of the battered childs. a Scattered and multiple rib fractures date differently. b Another case. The oblique projection shows a recent fractures located near the posterior rib articulations (arrows)

The child frequently presents in a situation of cris is , with inconsolable cr ying ass ociated with respiratory di fficulty. The presenc e of multipl e fractures, of different dat e, in different regions of th e thoracic ribs determines the on set of pain with eve ry breath , assoc iat ed with a redu ction in the elas ticity of th e tho racic wall. The frequency and depth of the respiratory actions progressively reduces , resulting in stagnation of sec retions and th e app earance of dysventilatory events, infectiou s phenomena, and ultimately dyspn ea and serious respiratory insuff iciency. Specific fractures are located at th e posterior co stal arch, since the energy of shaking trauma is di scharged near the co stal- ver tebral junction, i.e. at the point of gr eatest rigidity. However, characte ristic frac tures are also located along a lin e at mid- axill ar y level of the front and rib cart ilage, ma inl y in associ ation with crushing traum as. Non-rece nt fractures are invariabl y characteri zed by coarse and volum inou s bon y calluses that extend to formation of mult inodular "bea ds" .

11.6

Differential Diagnosis

The contribution of the radiologi st is essenti al to avoid hasty judgments or incorrect diagnosis, which can have serious con sequence s in such a del icate context as that of child phy sic al maltreatment. The non-radiographic diagnosis of accidental bony lesion s is lar gel y a diagnosis of exclusi on, and as such as ks for a suitable colla bora tion among th e variou s involved exper ts, in light of a careful evaluation of th e attitude and the state ments of their par ent s, of family memb ers, and of tho se accompanying the child.

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The principal differenti al diagnoses are repr esent ed by the following pathologies: defect ive osteogenesis infantile cortic al hypero stos is dysmetabol ic bone disease of premature infants Menk es disease rick ets associated with vitamin D defici enc y rick et s not ass ociated with vita min D defi ciency cong enit al syphilis scurvy cong enit al insensitivity to pain.

11.6.1

Defective Osteogenesis Defect ive osteogenesis is manifested by qualitative and quantitativ e alte ration of collag en with involvement of different gene loci , and is characterized on the basis of pattern s of expressi on, of varying gravity. These may be subdivided acco rding to a variety of classifications, one of wh ich is the four-stage classification proposed by Sillence. Leth al (type II to lib), severe (type III and some expression s of type II), and regr essive (type la, Ib, IV) form s are described . The probl ems of differenti al diagno sis hardly concern the lethal forms, which are often diagno sed in utero on the basis of ultrasonog raph ic evidence of spontaneous fractures before birth , or shortening or deformation of the limb s, and related to possible isolat ion by amniocentesis of the respon sible gene or related bioch emical alteration. In subjects who are affected, the generali zed struc tura l rarefaction is very evident , as skeletal deformation s and mult ipl e fractures, charac ter ized by exuberant calluses, which determ ine a "b amboo-reed" feature of the long bon es of the limb s. Some var iable cha ract eristics of the illness may, however, lead to incorrect inter pretations: cerebral hemorrhages, hematomas, hemarthrosis, and ecchymosi s of the soft parts, cap illa ry fragi lity, and platelet abnorma lities areas of circum scribed cutan eous aplasia, with app earanc e that is simi lar to sma ll ulcerations or foci of scar tissue joint dislocations as a result of capsulo-ligame ntous laxity diffuse hypotonia. The following can creat e great diffi culti es for interpretation of skeletal lesions in some non-l ethal form s: mult ipl e costal fractures of different dating diaph yseal fractures from different dates with exubera nt callu s and signs of inadequate car e fractures of the vertebra l bodie s. The disorder also includes lesion s that are occ asionally found, which are underestim ated, for which the dyn ami cs and traum a are uncle ar, and for which an unconvinc ing expl anation is given.

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Fig.11.11 Newborn. Defective osteogenesis. Babygram front (a) and lateral (b) projection. Scattered and multiple rib fractures date differently, fractures of the vertebral bodies, "bell aspect" of the thorax, thin ribs and horizontal cotyloid roofs

Som e clinical signs , which are oth erwi se typical, are not always present : blu e sclera characteri stic facies he aring problem s. The same genetic diagno sis pre sent s problems of interpretation and is obt ained with difficulty. Bone loss, with reduction in cortical thickness, hypo-ossification of the skull and the pre sen ce of wormian bones are frequent radiographic ob ser vat ion s. In a signif ica nt number of cases, the radiograph ic examination of the skeleton gives eviden ce of a narrow che st, thin rib s, stumpy ili ac wings, and hori zontal cotyloids (Fig. 11.11). In abs olute term s, the defective osteogenesis represent s the mo st common differenti al diagnosti c ques tion in cases of suspicion for "battered child" .

11.6.2

Infantile Cortical Hyperostosis (Illness of Roske-De Tone-Caffey-Silverman) Infanti le co rtical hyperosto sis is a form of del ayed chondro-perio stal hyp ero steoge nesis that is alread y present in utero, for wh ich an early d iagno sis is po ssibl e around th e fi fth month of pregnancy, by ant enatal ultrasonograph y. The syndrome , is however, usuall y d iagnosed later, within th e f irst two years of life.

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Fig. 11.12 Newborn. Infantile cortical hyperostosis. Hyperostosis of the tibial diaphysis

Clinically the illness causes swelling and deformation of the limb s, edema, and pain of th e soft part s, vari able degr ees of impai red general health , fever, and incr eased erythrocy te sedime ntation rate and alka line pho sphatase. Th e illn ess has a slow but ben ign evolution, with regressi on of bon e lesion s without sign ificant sequelae . Identific ation of events of hyperostosis of the long bones of the limbs (Fig. 11.12), but also of some flat bon es such as th e shoulder blad es and the j aw, is esse ntial for diagnosis.

11.6.3

Dysmetabolic Bone Disease of Premature Infants Dysmet aboli c bone disease of prem ature infant s lead s to many radiographic man ifestation s th at can lead to problems of diffe rent ial diagnosis: angular fractu res of the met aphy seal cortex subperiosteal hem atom as calci fied "s leeves" diaph yseal fractures epiphyseal detachment rib fractures defo rmations of th e "cup " of the chondro-costal junction .

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The illn ess is cla ssified into four stages (0 to 3, based on incr easing levels of severi ty) and fractures onl y appear in the mo re seve re forms , cor respond ing to stage 3, while in all oth er stages the condi tion is clin icall y silent. All subjec ts are, however, preterm infants and have low weight for ges tationa l age . Radiog raph ic evide nce shows diffuse loss of bon e, which has a spongy trabecular app earanc e, and there is characteristic invol vement of the bon es of the skull. There is also invol vement at metaph yseal level, with height ened irre gularity of the area of prov isional ca lcific ation and the fi nding of typical "si ckle-shaped spurs" . Ultras onogra phic assessment of the level of bon e mineral ization may be useful for a defin itive diagno sis. The disease is determin ed by an insuffici ent supply of minerals, parti cul arl y phosphorus, result ing in a calcium defici enc y of bon e. However, high levels in the blood ca lcium and alkaline pho sphatase, and insufficient levels of pho sphorus in the blood are not con stant.

11.6.4 Menkes Disease

In Menke s disease, loss of structural bone den sity, ass oci ated with met aphy seal and cortical hyperoste al alterations and associated genetic characte ristic s (sex-linked recessive tran smission) , are man ifested as: a defi cit of copp er absorption alterat ions of the ar teries microcephal y wormi an bon es abnormaliti es of the hai r hypoton ia, convulsions statural and ment al retardation.

11.6.5 Rickets

In the variou s form s of ricket s, which are characterized by blood chemistry and from particular genetic evaluations , the main obser vation is of fragmentation of the metaphyseal car ti lage of the long bones of the limb s in comparison to lesion s that involv e the metaph yseal cortex. In rickets the diaph yses are bent and curve d and undergo angular fractures, oft en "gree nstick", which never completely break. The reparative callus is usually extuberant, but littl e ca lcifie d, and it ossifi es slowly. Perio stoti c "sl eeves" and " shells" develop late and are mildly calcified.

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11.6.6

Congenital Syphilis Congeni tal sy phi lis is also a pathology that is con stantl y increasi ng in industri alize d countries (0 .5/10 cases in eve ry 100,000 live births), and is determ ined by th e tran smission of Trepon ema pallidum from th e infect ed moth er to the fetu s through the placenta dur ing the period of inc ubation (from 10 to 90 days), or dur ing the pr imary and secondary stage of infec tion. Th e illness is rarel y already app arent at birth; the symptoms mor e oft en appear aft er some month s and are determ ined by involve me nt of a large proportion of org an s, part icul arl y the liver, splee n, kidneys, pancreas, and skele ta l apparatus. Osteol ytic areas with blurred margins appe ar in th e flat bon es and skull. Th e epiphyses of the appendicular bon es are typ icall y spare d, while at diaphyseal level th ere is ev ide nce of perio sto sis, cor res pondi ng to variou s struc tural modificat ion s of the metaphyses, which can be ob served in conjunction with alterations of trop ism with transverse rad iotr an sparent band s, and erosi on and fra gm en tation of thick ened pro cesses. Th e destructive lesion s are painful and acc ompanie d by hypomobilit y of all the affected limb s (particul arly the uppe r limbs) , within a picture known as pseudoparalysis of Parrot. Al so characteri stic is the appearance of de structive change s loc ated at the symmetrical level of both tib ias, on the metaphyseal med ial side, known as the sign of Wimberger (Fig. 11.13) .

Fig. 11.13 Infant with congenital syphilis. Radiograph of the lower limbs showstypical erosivechangesat the metaphyseal proximal tibia (Wimbcrger sign) (arrows)

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Ce rta in di agnosis is a lm o st ex cl usi vely obtained from serologi cal inv estigations, th at allow m ea surem ent of spe c if ic an ti bod ies, such as Trepon ema pallidum hem agglutin ation (TPHA), fluore sc ent treponem al antibody-absorb ed ( FTA-ASS), and particularly th e immunoglobul in (Ig) FTA-ASS IgM , wh ich det ect s an ti bo dies produced exc lusively by th e fetus. Th e exami na ti ons that ar e more wid ely avai lable such as Ven er eal Disease Research Laboratory (VORL) and rapi d plasm a reagin (RPR) do not exc lude fal se-posit ive results (although values ra ised fourfold in comparison to mat ernal value s are very indi ca tive), sin ce positive results can re fle ct transplacental pass age o f maternal Ig G.

11.6.7

Scurvy Scurvy is a ve ry rare d isease caused by a defici ency of v ita mi n C, which can occasi on ally pr esent in th e n eon at e or very youn g ch ild . It induces a lte rations in ske le ta l feature s, suc h a s met aphyseal den se lin es of Frankel and ra di o luce n t ar ea s (sites o f pathological fracture) , or angular spur s (spurs of Pelkan) in th e re cove ry ph a se. Th ere is assoc ia ted diffuse subperios tea l hemorrhage, and appear ance of periosteal sleeves .

Suggested Readings Augarten A, Laufer J, Szeinberg Act al (1993) Child abuse, osteogenesis imperfecta and the grey zone between them. J Med 24:171-175 Caffey J (1946) Multiple fractures in the long bones of infants suffering from chronic subdural haematoma. AJR Am J Roentgenol 56:163-173 Carty H, Pierce A (2002) Non-accidental injury: a retrospective analysis of a large cohort. Eur Radiol 12:2919-2925 Kempe CH, Silverman FN, Steele BF et al (1962) The Battered Child Syndrome. J Am Med Assoc 181:17-24 Mendelson KL (2005) Critical review of temporary brittle bone disease. Pediatr Radiol 35: I0361040 Miller ME, Hangartner TN (1999) Temporary brittle bone disease: association with decresed fetal movement and osteopenia. CalcifT issue Int 54:137-143 Paterson CR, Burns J, McAllion SJ (1993) Osteogenesis imperfecta: the distinction from child abuse and recognition of a variant form. Am J Med Genet 45: 187-192 Ruess L, O' Connor SC, Quinn WJ et al (2003) An animal model for the classic metaphyseal lesion of child abuse. Pediatr Radiol 33:s I 12 Tardieu A ( 1860) Etude medico-legale sur les sevices et mauvais traitement exerces sur des enfants. Annales d'hygiene publique et de medecine legale, Paris, 13:361-398 Williams RL, Connolly PT (2004) In children undergoing chest radiography what is the specificity of rib fractures for non-accidental injury? Arch Dis Child 89:490-492 Zimmerman S, Makaroff K, Care M et al (2005) Utility of follow-up skeletal surveys in suspected child physical abuse evaluations. Child Abuse Negl 29: I075-1083

12.1

Introduction

Child abuse is a top ical issue in modern society and has socia l and medic al implic ations that directl y conce rn the doctor, both as a private citizen and as a health professional. The varie ty and the pecul iarit y of abuse inj uries, as the World Health Organization decl ares [I] , requires a multidisciplinary and multispe cialty approac h, wh ich mu st beg in with an accura te med ical examination whe re diagno stic imaging becom es esse ntia l. The radio log ist, by identifyi ng the chi ld abuse , has great responsibility in conn ect ion with thr ee basics: identificat ion of traum at ic injuries differential diagnosis between accidenta l inj ury and abuse use of the opt imum investigationa l ima ging method to prove th e exis ten ce of inj ury. Aside from cases of sexual violence and abandonment/negligence of a ch ild, whe re the radiologi st can make complementary inquiries for diagno sis, batte red child syndrome repr esent s one of the mo st typical for ms of ill-treatme nt of child ren , characteri zed by micro - and macro-traumas inflic ted using natural means (such as the hand s, feet, elbows, and so on) or other objects (sticks, belts, chain s, etc) . The se traum as result in different kinds of injuries (ecchymoses, lace rated and contused wounds, luxations, fractures) to the mu sculoskel etal sys tem, which clearl y show the presence of abuse . As long ago as 1946, the Radio logist Caffey was th e first who found and de scribed new types of fracture and osseou s lesion s ob ser ved in batte red ch ildren, especi ally among younger children [2] . Later , in 1962 , Kempe and cowo rk-

M. Solarino ( ~) Section of Radiology, "Fallacara" Hospital, Triggiano - Sari, Italy Imaging of Pediatric Bone and Joint Trauma. Fabio Martino et al. (Eds.) © Springer-Verlag Italia 20II

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ers coined the expressi on "battere d child syndrome" by revea ling in adva nce the future guidelines [3-5]. With th is definit ion they grouped together the clinical and radiologica l signs that characterize the phenom enon of beaten children. Since then, many other reports in intern ational scie ntific journal s have shown different aspects and model s of this kind of abuse, to draw the atte ntion of the medical community to the problem, which, althou gh stea dily escalating, had been totall y disregarded [6-10]. Today there are some internati onal examples of gu idelines and standards of procedure relating to the radiologis t's role in the presence of a suspected "b attered child syndrome" . The American College of Radiology drew up some guidel ines to categorize radiologic al inquires according to the age of the child « 2 years, >5 years) and to the presence or abse nce of physical or neurological symptopatology (Box 12.1) [II]. Magnetic resonance (MR) is a useful method for investig ating a child under the age of 2 years, becau se at that age it is easy to detect the presence of a direct traumatic brain injury (by blows or by a fall). On the other hand, the use of the computed tomog raphy (CT) of the skull in a "b attered child" older than 5 years is a valuable method for revealing subdural interhemispheric hemorrhages as a consequence of shaking inj ury. A preliminar y objective exami nation of the child mu st ant icipate a radiodiagnostic surv ey. The rating used to evaluate the relev ance of the radiological investig ation performed in relation to the clinical pictu re and to the age of the child, shows that the survey of diagno stic investigation must be carried out on a case-by-c ase basis, if child physical abuse is suspected. If there are suspici ous non- accident al inj uries to children, the Brit ish Society of Pediatric Radiologi sts recommends adopting standard procedures [12] : there are several investigations, all of which need an initial clini cal evaluation of the child. It is important to focu s attention on the qualit y of the radiod iagno stic instr ument used (such as digital radiology, with extreme caut ion regarding techn ical paramete rs relating to the radiobiological danger), and the importance of involving competent health per sonne l. The main characte ristics of the se procedures are: attention to the importance of a pano ramic radiologica l investigation, if there is suspicion of abuse, by focu sing attention on specifi c anatomical areas a "real" collaborat ion between radiology technicians and the radiologis t during this kind of investigation, for radiological procedures the possibil ity of using control investigat ion some week s later, if there are suspiciou s abuse inj uries (such as costal fracture s). The protocol s propo sed by the Section of Radiology of the Americ an Academy of Pediatrics [13] are ver y interesting for two reason s. On one hand they show the utility of panor amic radiology of the skeleton, in cases of suspicious violence to children unde r the age of 2 years; on the other hand, they decl are the importance of a good evaluation of possible thoracic-abdominal injur y: this kind of localization could be linked to an abu se inj ury. In additi on to the useful different ial diagnosis between accidental inj ury and abuse, the protocol s provide for the performanc e, in the first ins tance , of a CT exami nation (tho rax and abdomen) and a subsequent control through ultrasonography of the abdom en.

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Box 12.1 ollege of Radiology: physical child-abuse [II]

R appropiatcncss criteria.

uspcctcd

Fir 'I scenario: child 2 years of age. or younger: with clinical suspicion ofabuse, bill without any evident focal signs or symptoms The most basic imaging examination is the skeletal survey. characterized by frontal and lateral views of the skull and a single frontal view of the long bones of the lateral vertebral column. and thoracic and abdominal frontal view. Oblique radiographs of the ribs. by detecting fractures as a consequence of abuse. are part of the initial skeletal survey. A 1R of the skull could be a valid instrument for a legal documentation of the abuse. Second scenario: child 2 year ofage, or YOl/I/ga, with cranial trauma, bill without anyevident 'igll of neurotogicul abnormallty A skeletal survey is recommended in the event of a clinical suspicion of abuse. Ifit appear ' negative. but there is a high suspicion of abu sc. a IR of the encephalon could be appropriate for the legal documentation of abuse. MR is more sensitive than T in detecting and dating brain parenchyma trauma ' without radiation exposure. Third scenario: child 1/1' 10 5 y ears old with neurological signs and symptoms, and a suspicion ofabuse with or without any other injuries A careful clinical assessment is essential. A non-contrast T scan of the brain should be performed if the child presents neurological traumas . If the scan does not show significant lesions needing a neurological intervention. the child should be stabilized and. if necessary. an urgent MR study of the brain with sequences in T I and T 2. in addition to an inver 'io n recovery should be required by the neurologist. If thc child's clinical condition i. constant but there are neurological symptoms (transient loss of consciousnc 's which conditions the alteration of mental statu '. retinal hemorrhage), IR represents the first diagnostic investigation for evaluation . Fourth scenario: child ofany age with iuspicious visceral injuries tha) are inconsistent with the clinical hi .tory and/or a clinical examination ora laboratory .1'1111(1' and without lilly satisfactory explanation Thi: requires an abdominal and pelvic T with contrast medium (or an echography) and a TI IR of the encephalon. ome vi .ccral injuries would include: pancreatic pscudocysts. hemorrhage of the suprarenal capsules. bowel perforation (after blunt trauma). contusions or laceration of viscera. or traumatic bladder perforation. In this selling. all of these injuries should be considcred signs of abuse. ome radiologists prefer not to usc oral contrast for the T study: however, there is no clear documcntation of the superiority of either technique: therefore. the issue of oral contrast should be left to the discretion of the radiologist.

What was stated earlier is only one example of the main directions the radiologist follow s during diagno sis of child abuse. It stands to reason that, in "battered child syndrome" , a traum atic action of mu ch gre ater gravi ty could include every anatomi-

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cal region. As well as the age of the child, the site of trauma and clinical confirmation of possible pre-existent or concomitant pathologies would condition the cho ice of appropriate radiodiagnostic tests, with the exception of panoramic radiography of the skeleton (known as "best inquiry") . As result, the use or not of contrast medium for the execution of a CT will depend not only on diagnostic suspicion, but also on its real purpose. In any event, the person who exercises parental authority or guardianship, in the event of a suspicious intrafamilial abuse, should give informed consent. It follows that such tests could lead to therapeutic treatment procedures and also have legal implications, in the event of tests for abuse.

12.2

Current Regulations and Medical-legal Considerations In 1990, the United Nations approved the Convention on the Rights of the Child. A paragraph of the text titled " Protection from abuse and neglect" established that "The State shall protect the child from all forms of maltreatment by par ents or others responsible for the care of the child and establish appropriate social programs for the prevention of abuse and the treatment of victims" . In 2002 , the " Optional Protocol to the Convention on the Rights of the Child on the sale of children, child prostitution and child pornography" was approved which demanded (article 8) that all Stat e Parties adopt appropriate measures against child abuse. In 2008 the main rights of the child resolution was approved: in the third paragraph of the text titled "Elimination of violence against children" it was specified that the United Nations "Condemns all forms of violence against children, including physical, mental , psychological and sexual violence, torture and other cruel , inhuman or degrading treatment, child abuse and exploitation , hostage-taking, dom estic violence, trafficking in or sal e of children and their organs, paedophilia, child prostitution, child pornography, child sex tourism, gang-related violence, bullying and harmful traditional practices" and urges States to strengthen efforts to prevent and protect children from all such violence through a comprehensive approach and to develop a multifaceted and systematic framework and strengthen legislation to prohibit and eliminate all forms of violence against children . In Italy, as well as in many other west ern countries , legislation against child abuse and every kind of violence are already incorporated in the penal code. The role preventing against this crime as demand by the United Nations is oft en attributed to physicians who are sometimes involved in such cases. The entire medical profession, including radiologists, is bound by Italian law to cooperate with police authorities to prevent and combat crime. The protection of health and the full respect of personal liberty are fundamental values guaranteed by the Italian Constitution (art. 13,32). The medical profession must safeguard all citizens and, in particular, minors, against "intrafamilial childhood maltreatments" or "corrective measures abuse", as also stated in article 571 and 572 of the Penal Code (PC) as well as in articles 581 ("beating") and 582-583 ("personal injury") . In the

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event of maltr eatm ent , viol enc e and abu se, the physici ans have a fundam ent al role in identi fying such crim es and, as a consequence, avoid children still being the victim of their perpetrators. Art icle 32 of the Medical Deontology Code (2006) states that the doctor must protect child ren in cases of physical or psychological maltreatm ent or sexual abu se, and in the event of oppo sition from the legal guardian s, the doctor must report to the appropriate legal authorities. Also, article 365 of the PC obliges all medi cal workers to notify the judicial autho rities whenever they have provid ed "assistance" or "care" in cases present ing the characteri stics of an officiall y pros ecu table crim e. Thi s appl ies, for example, to a radiologist who identi fies signs of child abus e in his or her private or publ ic practice. Thi s obligation is even mor e comp elling if the specialis t works within the National Health Service, where he or she act s as a public officer (ar t. 357 and 358 PC) and has a dut y to report any instanc e of crime that has been brought to his or her attention (art. 361-362 , PC) . Violation or neglect of this obligation is an offenc e against the administra tion of ju stice. Failure to compl y with this dut y is malfeasanc e in office when it is asce rtain ed that the health professional wilfull y and knowingl y fail ed to repor t or delayed reporting the crime.

12.3

Conclusions

The phenom enon of child abuse represents one of the most top ical and, at the same tim e, controversial subjects in mod ern soci ety. Too often we hear of presum ed physical , psychological , or sexual child abuse based on psychological evaluations without any reference to the medical follow-up or specialist investigation s that could unequ ivocall y con firm or exclude this suspicion. The compl exity of child abuse requ ires a multidi scip linar y, mult ispecialty appro ach in which the pediatr ic radiologist plays a key role. Pediatr icians or orthopedic surgeons are unabl e to interpr et the injur ies identifie d on imaging studie s. Only pediatr ic radiologists possess the competenc e to distingui sh between accide ntal and abu sive injur ies. In fact, they have the knowl edg e to determine the time of mineralization of skeletal segments, recon struct the mech anism of injuri es in relation to the osteoarticul ar system, and interp ret imaging findings. Reporting child abuse is invariably a very delicate question , especially becau se it always involves the families. Although a mere suspicion of abus e is sufficient for current regulat ions, the professional must be aware of the consequenc es of a misdiagno sis for the famil y and the victim. Therefore, the radiologi st is required to additionally make an educated social judgement in evaluating the case in terms of collecting a compl ete clinical history and carefully interpreting the imaging findings. Implementation of guidelines and proto col s, together with cooperation between several specialists, will help produce a methodologically flawless evaluation of the true extent of this serious problem, which has been neglected and under- reported for too long .

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

10.

II. 12. 13.

World Health Organization (2002) World report on violence and health. World Health Organizatio n, Geneva. Caffey J (1946) Multiple fractures in the long bones of infants suffering from chronic subdural hematoma. AJR Am J RoentgenoI 56:163-1 73. Kempe CH, Silverman FN, Stee le BF et al ( 1962) The battered-child syndrome. JAM A 181:17-24. Caffey J (1972 ) The parent-infant traumatic stress syndrome (battered baby syndrome). AJR Am J Roentgenol 114:217-225 . Silverman F ( 1972) Unrecognized trauma in infant s, the battered child syndrome. Radiology 104:337-339. Loder RT, Bookout C ( 199 1) Fracture pattern s in battered children. J Orthop Trauma; 5:428433 . Kleinman PK, Marks SC ( 1995) Relationship of the subperiostea l bone collar to metaphyseal lesions in abused infant s. J Bone Joint Surg Am 77:1471-1476. Strouse PJ, Owings CL (1995) Fractures ofthe first rib in child abuse. Radiology 197:763- 765 Mandelstam SA, Cook D, Fitzge rald M, Ditchfi eld MR (2003 ) Complementary use ofradiological skeletal survey and bone scintigra phy in detection of bony injuries in suspected child abuse. Arch Dis Child 88:387-390. Tung GA, Kumar M, Richard son RC, Jenny C, Brown WD (2006) Comparison of accid ental and nonaccidental traumatic head injur y in children on noncontrast computed tomography. Pediatrics 118:626-633. Slovis TL, Smith WL, Strain JD et al (2005) Expert panel on pediatr ic imaging. Suspected physical child-abuse. American College of Radiology (ACR), Reston (VA). Bristish Society of Paediatric Radiol ogy. Stan dard for skeletal surveys in suspected non-accidental injury (NAI) in children. http://www.bspr.org.uk/nai.htm (accessed 19 January 20 I0). American Academy of Paediat rics (2000) Section on radiology: diagnostic imaging of child abuse. Pediatrics 105:1345- 1348.

Suggested Readings Akduman EI, Launis GD, Luisiri A (2005) Skeletal and viscera l radiological imaging. In: Giardino Ap,Alexander R (eds) Maltreatment: a clinical guide and reference, 3 edn. GW Medical Publishing, St Louis, pp 13-3 6. Case ME, Graham MA, Handy TC et al (200 I) National Association of Medica l Examiners ad hoc Committee on Shaken Baby Synd rome: position paper on fatal abusive head injuries in infants and young child ren. Am J Forensic Med Patho l 22:I 12-122. Drvaric DM, Morrell SM, Wyly 18 et al (1992) Fracture patterns in the battered child syndrome. J South Orthop Assoc 1:20-25. Introna F (2005) Gli obblighi giuridici del pediatra di fronte al bambino maltrattato, al minore abusato, all'i ncesto e altro. Zacchia 78:1-20. Kleinman PK, Marks SC, Blackbourn e B (1986) The metaphyseal lesion in abused infants: a radiologic-histopathologic study. AJR Am J Roentgenol 146:895- 905. Kleinm an PK, Mark s SC Jr, Nimkin K et al (1996) Rib fracture s in 31 abused infants: postmortem radiologic-histopathologic study. Radiology 200 :807-810.

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Macchiarelli L, Albarello P, Di Luca NM, Feola T (2005) Medicina legale. Miner va Medica, Torino, pp 1215-1219. Tenenbein M, Reed MH, Black OB (1990) The toddler's fractur e revisited. Am J Emerg Med 8:208- 214.