3251 Riverport Lane Maryland Heights, Missouri 63043 SKELETAL IMAGING: ATLAS OF THE SPINE AND EXTREMITIES, SECOND EDITION ISBN 978-1-4160-5623-2 Copyright © 2010, 2000 by Saunders, an imprint of Elsevier Inc All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher Permissions may be sought directly from Elsevier’s Rights Department: phone: (+1) 215 239 3804 (US) or (+44) 1865 843830 (UK); fax: (+44) 1865 853333; e-mail: healthpermissions@elsevier.com You may also complete your request on-line via the Elsevier website at http://www.elsevier.com/permissions Notice Neither the Publisher nor the Authors assume any responsibility for any loss or injury and/or damage to persons or property arising out of or related to any use of the material contained in this book It is the responsibility of the treating practitioner, relying on independent expertise and knowledge of the patient, to determine the best treatment and method of application for the patient The Publisher Library of Congress Control Number: 2009935763 Vice President and Publisher: Linda Duncan Senior Acquisitions Editor: Kellie White Associate Developmental Editor: Kelly Milford Publishing Services Manager: Catherine Jackson Senior Project Manager: Karen M Rehwinkel Design Direction: Jessica Williams Working together to grow libraries in developing countries www.elsevier.com | www.bookaid.org | www.sabre.org Printed in the United States of America Last digit is the print number: To my parents and siblings, who taught me the importance of hard work and persistence; to my mentors who taught me the importance of lifelong learning; to my students who provide continuous motivation; and to my co-authors, Tudor Hughes and Donald Resnick JAMT To my coauthor, John, who is clearly the first author And to my always-supportive family: my loving wife Kelly; my three wonderful boys, Geraint, Griffith, and Rhett; and my learned parents, Dorothy and Fred THH It was a great pleasure and a distinct honor for me to work with two skilled colleagues and friends, John Taylor and Tudor Hughes, whose efforts far overshadow my contributions to this text They brought organization, dedication, and enthusiasm to the project, sprinkled with good old-fashioned energy DR v PREFACE BACKGROUND We initially intended the Second Edition of Skeletal Imaging to be merely a modification of the First Edition We planned only on updating the original and adding new case material that illustrates the more recent advances in the imaging diagnosis of musculoskeletal disorders After all, only years had elapsed between publication of the first edition, and the beginning of research for this edition However, our survey of the literature published since 2000 persuaded us that a wealth of new information deserved synthesis and recognition Our major dilemma was not so much to decide what to include, but what to exclude, and still meet our two principal objectives—to limit the atlas to a single volume and to address the most important musculoskeletal disorders Accordingly, we have focused on disorders most frequently encountered in practice and on how those disorders appear on conventional radiography, CT scans, MR images, and to a lesser extent, radionuclide imaging and diagnostic ultrasonography WHO WILL BENEFIT FROM THIS BOOK? Radiologists, chiropractors, and other clinicians who routinely interpret images of the musculoskeletal system will find the second edition an indispensable everyday reference Radiology residents, chiropractic students, and other clinicians-in-training who are preparing for certification examinations can use it in the classroom, at the viewbox or monitor, and as a helpful study guide ORGANIZATION The second edition retains the same organizational strategy: arranging musculoskeletal disorders according to anatomic region This organization enhances the book’s value as a reference tool for practitioners and is a practical way for students to learn a logical and methodical approach to patient assessment Each chapter includes a description of the appearance of normal developmental anatomy and major anomalies and anatomic variants It also demonstrates the full range of the most frequently encountered pathologic conditions, including dysplasias, physical injuries, internal derangements of joints, articular disorders, and bone tumors, as well as metabolic, hematologic, and infectious diseases Specifically, Chapter 1, “Introduction to Skeletal Disorders: General Concepts,” consists of 19 tables summarizing the general characteristics of the most common disorders discussed and illustrated throughout the text These tables offer an overview of information, such as age of onset, sites of involvement, clinical features, and general imaging features This chapter was developed to avoid repetition of background material about disorders that affect several anatomic regions Chapters to 17 represent stand-alone monographs, each dealing with a specific anatomic site The tables in these chapters emphasize only the site-specific manifestations of each entity, and they provide a sense of the range of disorders that characteristically affect that site Furthermore, in each of these regional chapters, most of the important conditions are illustrated with routine radiographs, some of which are supplemented with conventional tomograms, CT or bone scans, MR images, or combinations of these In addition, the chapters dealing with spinal regions and joints contain tables and illustrations of the normal developmental anatomy of that region through infancy, childhood, and adolescence When reading these chapters, it may be useful, or even necessary, to refer to Chapter for a more detailed discussion of the general features of a particular disorder The major emphasis of this work, however, is on the illustrations that the authors believe represent the most characteristic or typical presentations of disease entities For the most part, the cases include commonly encountered disorders, although some disorders that are seen less commonly also are included because they are important to consider with regard to differential diagnosis Purposely, the illustrations are as large as possible to best display the imaging findings Each is accompanied by a detailed legend beginning with the primary diagnosis followed by a discussion of the imaging findings and any available and important clinical data When MR imaging is displayed, detailed imaging parameters are included in the legend At least one useful reference for each condition has been included The references are cited not only in the tables but also in the figure legends These reference citations indicate the major sources of material and serve to direct the reader to further discussion In Chapter 1, a bibliography of recommended readings includes many textbooks dealing with various aspects of skeletal radiology that served as sources for information It is our hope that by retaining the successful features and format of the First Edition, updating the text to reflect new information, and adding more case material that this edition will be as favorably received by readers and reviewers John A M Taylor Tudor H Hughes Donald Resnick vii ACKNOWLEDGMENTS For the Second Edition Many colleagues and friends who generously contributed so much to the first edition have done so again, in a variety of ways, for this revised second edition of Skeletal Imaging We are enormously indebted to Dr Brian Howard for contributing many more excellent case studies from his teaching files; to Stephanie Brown, DC, for compiling research material in the formative stages of revision; and to Gary Smith, DC, DACBR, Matthew Richardson, DC, and Laurie Rocco, DC, for carefully and thoroughly proofreading every chapter, word by word We thank Pete Broomhall for editorial advice and assistance and Karen Rehwinkel and the other professionals of the Elsevier team and Saunders for providing encouragement, advice, and assistance at every turn We are particularly indebted to our editors, Kellie White and Kelly Milford, for patiently and gently guiding us through every stage of production and for attempting to keep us on task and on schedule The original two authors of Skeletal Imaging are enormously indebted to Dr Tudor Hughes, a well-respected musculoskeletal radiologist and educator at the University of California, San Diego, and the second edition’s recently recruited third author His extensive knowledge and understanding of musculoskeletal disorders is matched by equally impressive skills in researching, factchecking, writing, and editing In addition to contributing hundreds of fascinating cases from his vast digital teaching files, he improved every chapter of Skeletal Imaging by making them more accessible to and productive for the reader John A M Taylor Donald Resnick John A M Taylor Tudor H Hughes Donald Resnick ix CHAPTER Cervical Spine 75 5 B A FIGURE 2–34 Congenital spondylolisthesis A, An anteroposterior radiograph reveals spina bifida occulta at C6 (arrow) B, Lateral radiograph shows minimal anterior displacement of C6 in relation to C7 and a neural arch defect consisting of incomplete ossification of the pedicles and articular processes of C6 (arrow) In addition, the C6 vertebral body is hypoplastic (Courtesy E.E Bonic, DC, St Louis, Missouri.) 25 B A FIGURE 2–35 Persistent (ununited) secondary ossification centers A, An anomalous ossicle is present adjacent to the tip of the T1 trans7 verse process and first rib (arrow) This probably represents failure of fusion of the secondary ossification center at the tip of the transverse process, a structure that usually fuses by the age of 25 years B, In this 40-year-old man, two small triangular opacities are evident adjacent to the anterior corners of the C6 vertebral body (arrows) These ossification centers, which usually fuse to the vertebral body by the age of 17 or 18 years, may fail to fuse and persist into adulthood These “limbus vertebrae” are variations of normal that may simulate a fracture 76 CHAPTER Cervical Spine C7 A B FIGURE 2–36 Cervical rib and elongated C7 transverse process.26 A, The left C7 transverse process is elongated and has a tapered, sharpened appearance (curved arrow) A small, articulating cervical rib is evident on the right (arrow) B, In another patient, the right C7 transverse process is elongated and tapered (open arrow), and a cervical rib with two articulations (arrows) is present on the left CHAPTER Cervical Spine 77 FIGURE 2–38 Hair artifact.5 Streaky, vertically oriented opacities are seen over the cervical spine and soft tissues of the neck This commonly encountered artifact results from overlying strands of hair (Courtesy E.E Bonic, DC, Portland, Ore.) FIGURE 2–37 Tracheal ring calcification.6 Prominent ringlike calcification of the tracheal cartilage is evident on a lateral radiograph of this 50-year-old woman Such calcification is common in the elderly, is clinically asymptomatic, and is of no significance (Courtesy E.E Bonic, DC, St Louis, Missouri.) A B FIGURE 2–39 Cervical lymph node calcification Lobulated accumulations of calcification (A-B) are evident within the paraspinal soft tissues of the neck These calcifications are consistent with lymph node calcification and should not be confused with the periarticular calcifications seen in connective tissue and crystal deposition diseases (Courtesy S Maskall, DC, Grand Forks, B.C., Canada.) 6,27 78 CHAPTER Cervical Spine FIGURE 2–40 Ossification of the stylohyoid ligament.28 In this lateral radiograph obtained in flexion, observe the vertical, linear ossified structure (arrows) overlying the prevertebral structures superior to the hyoid bone (open arrow) This represents ossification and elongation of the stylohyoid ligament, which usually is an incidental finding This structure may possess one or more articulations, it may fracture, and, in a condition termed Eagle syndrome, it may cause symptoms of pain, dysphagia, and a sensation of a lump in the throat The prevalence of ossified stylohyoid ligaments is higher in patients with mucopolysaccharidoses and diffuse idiopathic skeletal hyperostosis (DISH) TAB L E 2- Skeletal Dysplasias and Other Congenital Diseases Affecting the Cervical Spine* Entity Figure(s) 29 Achondroplasia Characteristics in the Cervical Spine Brain stem compression by narrow foramen magnum Spinal stenosis with posterior scalloping of vertebral bodies Vertebral bodies may be flattened Spondyloepiphyseal dysplasia congenita30 2-41 Hypoplasia of the odontoid with atlantoaxial instability Platyspondyly Mucopolysaccharidoses (MPS)31,32 2-42 MPS I-H (Hurler syndrome) Atlantoaxial instability may be present Rounded anterior vertebral margins with inferior beaking Posterior scalloping of vertebral bodies MPS IV (Morquio syndrome) Hypoplastic or absent odontoid with atlantoaxial instability Platyspondyly Posterior scalloping of vertebral bodies Fibrodysplasia ossificans progressiva33 Osteopetrosis34,35,141 Sheetlike ossification within soft tissues of neck Hypoplastic vertebral bodies and intervertebral discs Apophyseal joint ankylosis 2-43 Patterns of osteosclerosis: diffuse osteosclerosis, bone-within-bone appearance, sandwich vertebrae Osteopoikilosis36 Infrequently affects the spine Multiple punctate circular foci of osteosclerosis Marfan syndrome37 Scoliosis in 40%-60% of persons Posterior vertebral body scalloping from dural ectasia Atlantoaxial instability may be present * See also Table 1-2 CHAPTER Cervical Spine 79 FIGURE 2–41 Spondyloepiphyseal dysplasia congenita.30 This 5-year-old boy has platyspondyly, a hypoplastic odontoid process with atlantoaxial subluxation, instability, and craniocervical canal stenosis Respiratory and visual complications may be severe, and a rare lethal form exists termed hypochondrogenesis A B FIGURE 2–42 Mucopolysaccharidoses: MPS IV (Morquio syndrome).31,32 A, Sagittal reformatted CT image of the upper cervical region of a young child reveals agenesis of the odontoid, an important cause of atlantoaxial instability in patients with MPS IV B, Flexion radiograph of a 28-year-old man with MPS IV demonstrating the typical platyspondyly configuration of the vertebral bodies 80 CHAPTER Cervical Spine FIGURE 2–43 Osteopetrosis.34,35,141 Diffuse sclerosis predominates at the vertebral endplates of the cervical spine in this 15-year-old boy with osteopetrosis The radiographic pattern in the spine may be diffusely sclerotic, or osteopetrosis may be manifest as “sandwich vertebrae” or as a “bone-within-bone” appearance Generalized osteosclerosis in osteopetrosis results from an increased amount of bone, not from an increase in the percentage of mineralized bone per unit volume of tissue TAB L E 2- Cervical Spine Injuries: The Canadian C-Spine Rule A Decision Rule to Determine Which Patients Require Diagnostic Imaging After Sustaining Cervical Spine Trauma158 Discussion The Canadian C-spine rule can be applied to determine the need for diagnostic imaging in alert and stable patients sustaining cervical spine trauma and who are in stable condition Criteria are listed as follows: High-Risk Criteria Requiring Imaging • Age ≥ 65 • Dangerous mechanism of injury • Fall from meter (5 stairs) • Axial load to the head (i.e., diving) • Motor vehicle collision at high speed ≥ 60 miles (100 km) per hour • Rollover or ejection • Motorized recreational vehicles • Bicycle collision • Presence of paresthesia in extremities Low-Risk Criteria Presence of any one of these in the absence of a high-risk criterion allows clinical assessment of active range of motion: • Simple rear-end motor vehicle collision (this excludes being pushed into oncoming traffic, being hit by a bus or large truck, rollover, hit by a high-speed vehicle) • Sitting position in the emergency department • Ambulatory at any time • Delayed onset of neck pain (i.e., not immediate onset of neck pain) • Absence of midline cervical spine tenderness CHAPTER TA B L E -8 Cervical Spine Canadian C-Spine Rule Algorithm* Any high-risk factor that mandates radiography? Age Ն 65 years or dangerous mechanism or paresthesias in extremities No Any low-risk factor that allows safe assessment of range of motion? Simple rear-end motor vehicle collision or sitting position in the emergency department or ambulatory at any time or delayed (not immediate) onset of neck pain or absence of midline cervical-spine tenderness Yes No Radiography Unable Yes Able to rotate neck actively? 45° left and right Yes No radiography * Reprinted with permission from Stiell IG, Clement CM, McKnight D, et al: The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma N Engl J Med 349:2512, 2003 TA B L E -9 Cervical Spine Injuries With Stratification Based on Stability* Fracture Stability Ruptured transverse ligament of the atlas Least Type II odontoid fracture Burst fracture with posterior ligamentous disruption Bilateral facet dislocation Burst fracture without posterior ligamentous disruption Hyperextension fracture dislocation C2 hangman’s fracture Extension teardrop fracture (stable in flexion) Compression fracture of C1 (Jefferson burst fracture) Unilateral facet dislocation Anterior subluxation Simple wedge compression fracture without posterior disruption Pillar fracture Fracture of the posterior arch of C1 Isolated spinous process fracture not involving the lamina (clay shoveler’s fracture) * Modified from Trafton PG: Spinal cord injuries Surg Clin North Am 62:61, 1982 Most 81 2-44 2-45 2-46 Table 2-11 2-47 Table 2-11 2-48 Traumatic transverse ligament disruption40,160,166 Rotatory atlantoaxial fixation41-43,147,154,155 Burst (Jefferson) fracture44,147 Posterior arch fracture45,147 Figure(s), Table(s) Stable Variable Deemed unstable when the transverse ligament is ruptured or avulsed Variable Compressive hyperextension Axial compression Hyper-rotation Poorly understood mechanism Hyperextension-shearing and distraction Mechanism Most common fracture of the atlas Results from compression of the atlas between the basiocciput and the posterior arch of C2 during hyperextension injury 90% are bilateral; 10% are unilateral Heals slowly, pseudarthroses are common May be unilateral or bilateral Axial compressive loading causes compression of the lateral masses of C1 between the occipital condyles and the C2 articular processes, resulting in two, three, or four fracture fragments of the atlas ring (classic Jefferson fracture is four-part) Unilateral or bilateral displacement of lateral masses on open mouth view Normal lateral offset (pseudospread) of the atlas is common in normal children and may measure 4-6 mm Jefferson fracture should be suspected in patients with mm or more of total lateral displacement, and transverse ligament damage should be suspected in patients with more than mm of total lateral displacement seen on the anteroposterior view Permanent neurologic injury is uncommon with classic four-part Jefferson fractures Persistent pathologic fixation of the atlantoaxial joints in a rotated position such that the atlas and axis move as a unit rather than independently Patient typically has a persistent painful torticollis Occurs after rotational trauma, but also may occur after an inflammatory condition of the pharynx or upper respiratory tract, such as in Grisel syndrome Dynamic or functional CT is useful in identifying the presence and precise type of atlantoaxial rotatory fixation Rupture of the transverse ligament with or without associated fractures Atlantoaxial instability invariable: atlantodental interspace more than mm in adults and mm in children Rare: only 1% of all cervical injuries Transverse ligament damage (partial tears) from whiplash trauma can be detected on high-resolution proton-weighted MR images, but the reliability still needs improvement Nontraumatic causes of transverse ligament rupture much more frequent and include inflammatory arthritis, Down syndrome, anomalies, and infection Rare injury; almost always fatal Occurs with or without associated fracture Cranium usually is displaced anteriorly relative to the cervical spine Distance between the odontoid and basion is increased Characteristics CHAPTER Unstable Unstable Stability† Upper Cervical Spine Injuries* Atlanto-occipital dislocation38,39 Atlas Injuries Entity TABLE 2-10 82 Cervical Spine 2-50 2-51 Type II Type III Stable Unstable Stable Horizontal or oblique fracture line extends from the base of the odontoid into the cancellous bone of the vertebral body, typically exiting through the articular process of C2 into the C1-C2 articulation Anterior displacement occurs in 58% of cases and lateral tilting of the odontoid greater than degrees is present in about 66% of cases Nonunion occurs in less than 13% of cases Most common type Fracture occurs through the base of the odontoid at its junction with the C2 body; frequently disrupts the blood supply Nonunion occurs in more than 25% of cases Displacement (more than 60% of cases) and angulation (more than 25%) increase likelihood of nonunion Popular theory holds that os odontoideum actually represents a chronic nonunion type II odontoid fracture rather than a developmental anomaly Least common type: believed to be caused by alar ligament avulsion Unilateral oblique fracture through the tip of the odontoid above the transverse ligament Nonunion and displacement rare Most common axis fracture: 55% of C2 fractures; 7%-13% of all cervical spine injuries Up to 90% of affected patients are intact neurologically at time of injury but may develop late-onset neurologic deficit Fracture-dislocation may complicate odontoid fractures Anterior odontoid displacement from flexion forces Lateral odontoid displacement from lateral flexion or rotational forces Three types of odontoid fracture based on fracture location Extremely rare injury at C1 level Potential vertebral artery injury Extremely rare injury Fracture of the medial aspect of the lateral mass may result from avulsion by the transverse ligament Horizontal fracture seen on lateral radiograph produced by avulsion of the tubercle of the anterior arch by the superior oblique portion of the longus colli muscle and the anterior longitudinal ligament Often associated with fractures of C1 posterior arch and odontoid Continued * From references 46, 50, 51, 147, 158, 159 † Clinical instability here is defined as the inability to maintain vertebral relationships in such a way that spinal cord and nerve root damage are avoided and subsequent deformity and excessive pain not develop From White AA, Southwick WO, Panjabi MM: Clinical instability in the lower cervical spine Clin Orthop 109:85, 1975 2-49 Type I Complex and poorly understood mechanism including combinations of extreme flexion, extension, rotation, and shearing Lateral hyperflexion Usually stable Isolated transverse process fracture46,147 Axis Injuries Odontoid fracture47,48,147 Axial compression or lateral hyperflexion Usually stable Isolated lateral mass fracture46,147 Disruptive hyperextension Usually stable Anterior arch fracture46,147 CHAPTER Cervical Spine 83 2-53 Hangman’s fracture47-49 Stable Unstable Unstable Unstable Unstable Variable Usually stable Type I Type II Type III Extension teardrop fracture46 Avulsion fracture of C2 body from hyperextension dislocation46 Oblique fracture of body46 Isolated process fracture46 Varies according to type Highly unstable Stability† Hyperextension, rotation, hyperflexion, or direct trauma Combinations of axial compression and rotation Disruptive hyperextension Disruptive hyperextension Hyperflexion Hyperextension or flexion-distraction Hyperextension Varies according to type Distraction Mechanism Unilateral pedicle, lateral mass, or lamina Spinous process Oblique fracture through the C2 vertebral body below the odontoid and articular processes Results in widened anteroposterior diameter of the C2 vertebral body: “fat C2 sign” Severe injury: avulsion fracture of anteroinferior corner of vertebral body mediated through Sharpey fibers Usually occurs in lower cervical spine, but also seen at C2-C3 Frequently associated with acute cervical central cord syndrome Avulsion fracture of a triangular fragment of the anteroinferior margin of the body by the anterior longitudinal ligament Most common at C2, but may occur at any level Fragment may be displaced, distracted, or rotated More common in elderly persons with osteoporosis and spondylosis Usually not associated with neurologic deficit Anterior displacement or angulation with bilateral facet dislocation Anterior displacement or angulation with C2-C3 disc injury Nonangulated, nondisplaced (