Imaging of the Musculoskeletal System

2183 Pages·2008·174.788 MB·English

by  Thomas Pope, Hans L. Bloem, Javier Beltran

Imaging of the
Musculoskeletal System
Volume 1
Thomas Lee Pope, Jr, MD, FACR
Professor of Radiology and Orthopaedics
Medical University of South Carolina
Charleston, South Carolina
Hans L. Bloem, MD, PhD
Chairman and Professor of Radiology
Leiden University Medical Center
Leiden, The Netherlands
Javier Beltran, MD, FACR
Clinical Professor of Radiology
Mount Sinai School of Medicine
Chairman, Department of Radiology
Maimonides Medical Center
New York, New York
Director of Medical Education
Franklin & Seidelmann, Inc., Subspecialty Radiology
Beachwood, Ohio
William Brian Morrison, MD
Associate Professor of Radiology
Thomas Jefferson University
Director, Division of Musculoskeletal and General Diagnostic Radiology
Thomas Jefferson University Hospital
Philadelphia, Pennsylvania
David John Wilson, MBBS, FRCP, FRCR, MFSEM
Consultant Musculoskeletal Radiologist
Nuffield Orthopaedic Centre
and Oxford Radcliffe Hospital
Senior Clinical Lecturer
University of Oxford
Oxford, United Kingdom
FM Vol-I-X2963.indd iii 2/20/2008 1:06:57 PM
1600 John F. Kennedy Blvd.
Ste 1800
Philadelphia, PA 19103-2899
Imaging of the Musculoskeletal System ISBN: 978-1-4160-2963-2
Copyright © 2008 by Saunders, an imprint of Elsevier Inc.
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Knowledge and best practice in this field are constantly changing. As new research and experience
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priate. Readers are advised to check the most current information provided (i) on procedures featured or
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The Publisher
Library of Congress Cataloging-in-Publication Data
Imaging of the musculoskeletal system / [edited by] Thomas Lee Pope Jr., [et al.]. 1st ed.
p. ; cm.
ISBN 978-1-4160-2963-2
1. Musculoskeletal system—Imaging. I. Pope, Thomas Lee.
[DNLM: 1. Musculoskeletal Diseases—diagnosis. 2. Diagnostic Imaging—methods.
3. Musculoskeletal System—injuries. WE 141 I305 2008]
RC925.7.I4356 2008
616.70754—dc22 2007000890
Acquisitions Editor: Judith Fletcher
Developmental Editor: Jennifer Shreiner
Publishing Services Manager: Tina Rebane
Project Manager: Norm Stellander
Design Direction: Steve Stave
Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1
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1
C H A P T E R C H A P T E R
Introduction and General
Principles
John H. Harris, Jr.
In this chapter concepts are identified and described whether the injury should be considered emergent or
that are intrinsic to musculoskeletal trauma, such as the urgent based on the findings of the examination and rea-
purpose of the imaging report, vector forces causing sonable medical judgment.
musculoskeletal injury, musculoskeletal injury terminol- Follow-up musculoskeletal injury examination informa-
ogy, and fractures and dislocations in which the associ- tion may be considered as “routine” and the information
ated soft tissue component—not routinely delineated by transmitted by written report. Should the follow-up study
conventional radiography—is the principal element of show related but unexpected findings, such as infection
the injury. Because most of the musculoskeletal injuries or change in position of fragments, the radiologist should
described in this chapter are discussed and illustrated transmit the findings directly to the attending physician or
in greater detail in the chapters on specific anatomic designee.
regions, this chapter can also serve as a quick synoptic In every instance, all deviations from normal, including
reference. artifacts, recorded on the examination must be included in
the report. All appropriate negative observations must be
PURPOSE OF THE IMAGING REPORT included as well.
With respect to CT and MRI, the technical factors and
The imaging report is not only the formal transmittal of imaging sequences, respectively, must be appropriate to
the findings of the examination but also serves as the the indications for the examination and should be included
basis of patient management, the source of comparison in the body of the report.
with subsequent examinations, a historic record, and
a source of possible research data. For all these reasons,
all musculoskeletal injury imaging reports must be as
accurate and thorough as possible. The report must be
dictated after critical observation, analysis, and synthesis
KEY POINTS
of the data present on the examination.
Timely transmission of information derived from the !Timely transfer of information obtained on a
musculoskeletal injury imaging examination to the attend- musculoskeletal imaging study to the appropriate
ing physician is essential for proper patient management. referring physician is the primary responsibility of the
interpreting radiologist.
The initial examination (conventional radiography, CT,
!Emergent or serious unsuspected findings should be
or MRI) may be requested in acute or emergent circum-
transmitted immediately and directly to the referring
stances, in which event the radiologist should communi-
physician.
cate the findings directly to the attending physician or
!General knowledge of the fundamental principles
designated representative. In less acute or urgent circum- of trauma imaging as outlined in this chapter are of
stances, the information may be transmitted in the form of utmost importance for the adequate interpretation of
a written report. When the attending physician does not musculoskeletal imaging studies.
request a “stat” report, the radiologist should determine
3
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4 PART ONE " Injury
Digital imaging and electronic communication should and projections constituting the examination and always
preclude informal, “curb-side” verbal communication include the phrase, “In comparison with the previous
between the radiologist and attending physician. Informal examination of the (part or anatomic area) dated____,
verbal communication may lead to misinterpretation, mis- etc.” All changes between the previous and current exam-
understanding of the transmitted information, or even mis- ination must be carefully and accurately described.
diagnosis, with resultant patient mismanagement and the
potential for medical liability. When the radiologist and
BONE TYPES
attending physician do consult directly, the consultation
must be supported by a formal written report.
The different types of bone include the following2:
The Practice Guidelines of the American College
of Radiology recommend that the radiologist’s initial Long: length greater than width (e.g., femur, phalanx)
report consist of two parts: a heading called “Impression,” Short: cuboid shape (e.g., carpal and tarsal bones)
“Diagnosis,” or “Conclusion” and a descriptive portion Flat: two layers of compact bone separated by a thin
(body) frequently designated as “Comment.”1 The body of marrow space; usually preformed in a membrane (e.g.,
the report should describe the findings that prompted the sternum, ribs, scapula)
impression, diagnosis, or conclusion. Irregular: mixed shape (e.g., vertebra, pelvis)
If a single diagnosis is not possible, the impression, diag- Sesamoid: small, usually round or oval bones that develop
nosis, or conclusion should be expanded to include a rea- in tendons. Sesamoid bones are usually flat on the side
sonable differential diagnosis with the possibilities listed adjacent to the neighboring bone (Fig. 1-1).
in the order of likely probability. Accessory (supernumerary): arise from separate centers
The body or “comment” portion of the study should of ossification located adjacent to a parent bone and
indicate the part or anatomic region examined and the found most frequently in the foot (e.g., os intermetatar-
views (projections) obtained (e.g., “the cervical spine seum (Fig. 1-2).
was examined in anteroposterior, lateral, and open-mouth
projections”).
Follow-up examinations need not contain a “Diagnosis”
or “Impression”; however, they should indicate the views
! FIGURE 1-1 Sesamoid bones. The sesamoid bones on the plantar
surface of the head of the first metatarsal (arrows) are located in the
tendons of the adductor hallucis and the lateral head of the flexor
hallucis brevis and the abductor hallucis and medial head of the flexor
hallucis brevis muscles. Other sesamoid bones include the patella and the ! FIGURE 1-2 Os intermetatarseum (arrow) between the base of the
pisiform bone of the wrist. first and second metatarsal bones.
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CHAPTER 1 " Introduction and General Principles 5
GEOGRAPHIC ANATOMY OF LONG AND
SHORT BONES
Long and short bones have their origin from primary and sec-
ondary ossification centers (Fig. 1-3). The primary ossification
originates in the mid shaft of the bone, with ossification pro-
gressing proximally and distally from that center. Secondary
ossification centers develop in the proximal and distal epiph-
yses, which unite with the metaphysis of the shaft at the
physis to provide longitudinal growth of the bone (Fig. 1-4).
Other secondary centers arise in cartilage and form apophy-
ses, which develop into tuberosities or exostoses from, or to
which, tendons and ligaments arise or insert (see Fig. 1-4).
Portions of long and short bones are designated as
“diaphysis” (shaft), “metaphysis” (transitional area between
the diaphysis and the epiphysis), and “epiphysis,” which is
the proximal and distal fused growth center (see Fig. 1-4).
TYPES OF MUSCULOSKELETAL INJURIES
Ligamentous Injuries (Selected Examples)
" Anterior subluxation (hyperflexion sprain) of the
cervical spine. This is caused by a primary hyper-
flexion mechanism of injury of the cervical spine
resulting in the disruption of the posterior ligament
complex (Fig. 1-5).
" Soft tissue Chance injury. This is a hyperflexion injury
of the thoracolumbar (T10-L2) spine in which the
vertebra at the level of the injury remains intact but
! FIGURE 1-3 Endochondral ossification. all ligamentous structures including the intervertebral
disk and the anterior and posterior longitudinal
ligaments are disrupted (Fig. 1-6). This injury, like the
! FIGURE 1-5 Disruption of the posterior ligament complex. Anterior
subluxation of C4 on C5 is characterized by widening of the interspinous
space (arrowhead), subluxation of the C4-C5 interfacetal joints (arrows),
! FIGURE 1-4 Geographic anatomy, humerus. and anterior rotation of the C4 vertebra relative to C5.
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6 PART ONE " Injury
A B
! FIGURE 1-6 A to F, Soft tissue
Chance injury of T12. A, Anteroposterior
radiograph of the thoracolumbar spine
shows rotation of T12 to the patient’s left
side. B, Lateral radiograph shows anterior
rotation of T12 with subluxation of the
T12-L1 apophyseal joints (arrow). C, Axial
CT images of T12-L1 show subluxation of
the right T12-L1 apophyseal joint (arrow)
and the “naked” left T12 facet (open
arrow).
(Continued)
C
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CHAPTER 1 " Introduction and General Principles 7
! FIGURE 1-6—Cont’d D, Axial CT of the T12-L1 area
shows the complete left T12-L1 interfacetal dislocation
(open arrow). E, Sagittal reformatted CT image shows
T12-L1 right interfacetal joint subluxation (arrow).
F, Sagittal reformatted CT image shows left interfacetal
joint dislocation (open arrow).
D
E F
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8 PART ONE " Injury
! FIGURE 1-7 Pelvic ring disruption with separation of the pubic symphysis (arrow) and each sacroiliac joint (open
arrow) without associated fracture.
Chance fracture, is associated with an approximate
20% incidence of intra-abdominal injury, such as to the
pancreas.
" Pelvic ring disruption. The pubic symphysis and one
or both of the sacroiliac joints are disrupted without
associated fracture (Fig. 1-7).
" Rupture of the Achilles tendon.
Skeletal Injuries
" Subluxation: partial disruption of a joint (Fig. 1-8).
" Dislocation (luxation): complete disruption of a joint
(Fig. 1-9).
" Fracture: break in the continuity of a bone (Fig. 1-10).
" Fracture-dislocation: a musculoskeletal injury in which
both disruption of a bone and complete dislocation of a
joint occur simultaneously (Fig. 1-11).
SKELETAL INJURY
Skeletal injuries are the result of the effect of the major
injury vector force on the involved bone. The major injury
vectors include axial load (compression), distraction,
bending, torsion, and traction (avulsion). The effect of each
major injury vector on a long or short bone is schemati-
cally illustrated in Figure 1-12. ! FIGURE 1-8 Subluxation of the radial head. The frontal radiograph
of the right elbow shows lateral subluxation (arrow) of the radial head
The same vector forces may be applied to the pediatric
with respect to the capitellum as one component of a Bado type III
skeleton. Injuries peculiar to the pediatric age group Monteggia fracture-dislocation of the elbow.
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CHAPTER 1 " Introduction and General Principles 9
! FIGURE 1-9 Posterior dislocation of the right femoral head with ! FIGURE 1-10 Comminuted fracture of the os calcis.
respect to the acetabulum.
! FIGURE 1-11 Fracture-dislocation. The lateral radiograph of the foot and ankle shows
a complete fracture through the neck of the talus (arrows) with posterior dislocation of the
separate proximal fragment (asterisk).
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