Systematic Checklist Approach to the Radiographic Interpretation of the Injured Wrist to Avoid Common Diagnostic Errors

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1 This issue of CDR will qualify for 2 ABR Self-Assessment Module SAM (SA-CME) credits. See page 8 for more information. Volume 38 Number 20 September 30, 2015 Systematic Checklist Approach to the Radiographic Interpretation of the Injured Wrist to Avoid Common Diagnostic Errors MAJ Matthew R. Minor, MD, COL (Ret) Liem T. Bui-Mansfield, MD, and MAJ (S) Bradley J. Carra, MD This module meets the American Board of Radiology s (ABR s) criteria for self-assessment toward the purpose of fulfilling requirements in the ABR Maintenance of Certification (MOC) program. Please note that in addition to the SA-CME credits, subscribers completing the activity will receive the usual ACCME credits. After participating in this activity, the diagnostic radiologist should be better able to identify the anatomic landmarks of the wrist on radiography and become familiar with a systematic checklist approach to the radiographic interpretation of the injured wrist. CME Category: Emergency Radiology Subcategory: Musculoskeletal Modality: Radiography Key Words: Radiographic Evaluation of the Injured Wrist, Systematic Approach, Traumatic Wrist Injury Radiography is the first-line imaging modality for the evaluation of traumatic wrist injury, which is encountered commonly in the daily practice of a diagnostic radiologist. Because Dr. Minor and Dr. Carra are Radiology Residents, Diagnostic Radiology Residency Program, SAUSHEC, Fort Sam Houston, Texas; and Dr. Bui- Mansfield is Adjunct Professor, Department of Radiology, USUHS, Bethesda, Maryland and Musculoskeletal Radiology Section, Department of Radiology, Brooke Army Medical Center, 3851 Roger Brooke Dr, Fort Sam Houston, TX 78234; liem.mansfield@gmail.com. The authors and all staff in a position to control the content of this CME activity and their spouses/life partners (if any) have disclosed that they have no relationships with, or financial interests in, any commercial organizations pertaining to this educational activity. The opinions and assertions contained herein are those of the authors and should not be construed as official or as representing the opinions of the Department of the Army, Department of the Air Force, or the Department of Defense. of the complex anatomy and overlapping structures of the wrist on standard radiographic projections, abnormalities of the wrist can be subtle and easily overlooked. Therefore, it is essential for radiologists to be proficient at the interpretation of wrist radiographs. The use of a checklist approach, and recognition of common injury patterns, potentially can increase radiologists accuracy when interpreting standard wrist radiographs. The objective of this article is to present a simple but thorough method for accurate radiographic evaluation of the wrist and to review some common injury patterns of the wrist. Introduction Radiographs usually are sufficient for the diagnosis of common wrist injuries. A systematic approach to the evaluation of wrist radiographs is essential to avoid missing wrist fractures and ligamentous injuries, which can result in significant long-term morbidity, including carpal instability, late carpal collapse, and severe degenerative arthritis. Radiographic Evaluation of the Wrist Common views of the wrist include posteroanterior (PA), lateral, and oblique projections. With the PA view, the wrist Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Lippincott Continuing Medical Education Institute, Inc., designates this enduring material for a maximum of 2 AMA PRA Category 1 Credits. Physicians should only claim credit commensurate with the extent of their participation in the activity. To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. This continuing medical education activity expires on September 29,

2 A B Figure 1. A: The normal PA view of the wrist shows the lazy M (round dotted line and black arro w head) and the carpal arcs of Gilula: arc 1 (#1 dashed line); arc 2 (#2 dashed line); and arc 3 (#3 dashed line). The cortical white line of the hook of the hamate (arrow) and the scaphoid fat stripe (white arrowhead) also are shown. B: Normal lateral view of the wrist shows a straight line through the axes of the radius, lunate, capitate, and third metacarpal. The normal pronator quadratus fat stripe is seen (arrow). should be in a neutral position, and half or more of the proximal cortex of the lunate should articulate with the distal radial articular surface 1 (Figure 1A). On the lateral view, a straight line should be able to be drawn through the axes of the distal radius, lunate, capitate, and third metacarpal, or the axes should be within 10 degrees of that straight line 1 (Figure 1B). For the oblique view, the wrist is pronated 45 degrees from the lateral, which improves evaluation of the radial corner of the wrist, the base of the thumb, the triscaphe joint (i.e., scaphotrapeziotrapezoid joint), and the dorsal triquetral margin. 2 More specific views include the PA projection with ulnar or radial deviation, carpal boss or off-lateral, dynamic anteroposterior (AP) clenched fist, specialized scaphoid carpal tunnel, and bridge. 3 These specialized views serve as problem-solving projections for indeterminate cases, and each view has its advantages for viewing the complex anatomy of the wrist. For example, in the setting of a suspected scaphoid fracture, the clenched-fist AP and PA ulnar-deviated views allow for better visualization of the scaphoid and for the evaluation of scapholunate instability. 1-3 In the PA view of the wrist, half or more of the proximal lunate cortical surface should articulate with the distal radial articular surface. For better visualization of a suspected scaphoid fracture, the clenched-fist AP and PA ulnar-deviated views are performed. Radiographic Anatomy of the Wrist The complex anatomy of the wrist derives from the two rows of four carpal bones, extrinsic ligaments, and intrinsic ligaments. This article reviews key osseous anatomy and key ligamentous injuries that are implied by radiographic abnormalities. However, a thorough review of ligamentous anatomy is beyond the scope of this article. The carpal bones and intrinsic ligaments form some of the most complex anatomy of the wrist, both on radiographs and cross-sectional images. Radiographic evaluation was somewhat simplified by Gilula in 1979 with the description of three normal carpal arcs on the PA view of the wrist. 4 The proximal arc, or arc 1, silhouettes the proximal articular surfaces of the scaphoid, lunate, and triquetrum. The middle arc, or arc 2, silhouettes the distal concave surfaces of the scaphoid, lunate, and triquetrum. The distal arc, or arc 3, silhouettes the proximal articular surfaces of the capitate and hamate. These arcs, as illustrated in Figure 1A, always should be The continuing education activity in Contemporary Diagnostic Radiology is intended for radiologists. Contemporary Diagnostic Radiology (ISSN ) is published bi-weekly by Lippincott Williams & Wilkins, Inc., Hunters Green Parkway, Hagerstown, MD Customer Service: Phone (800) ; Fax (301) ; customerservice@lww.com. Visit our website at LWW.com. Publisher, Randi Davis. Copyright 2015 Wolters Kluwer Health, Inc. All rights reserved. Priority Postage paid at Hagerstown, MD, and at additional mailing offices. POSTMASTER: Send address changes to Contemporary Diagnostic Radiology, Subscription Dept., Lippincott Williams & Wilkins, P.O. Box 1600, Hunters Green Parkway, Hagerstown, MD PAID SUBSCRIBERS: Current issue and archives (from 1999) are available FREE online at Subscription rates: Individual: US $ with CME, $ with no CME; international $ with CME, $ with no CME. Institutional: US $ , international $ In-training: US resident $ with no CME, international $ GST Registration Number: Send bulk pricing requests to Publisher. Single copies: $ COPYING: Contents of Contemporary Diagnostic Radiology are protected by copyright. Reproduction, photocopying, and storage or transmission by magnetic or electronic means are strictly prohibited. Violation of copyright will result in legal action, including civil and/or criminal penalties. Permission to reproduce in any way must be secured in writing; go to the journal website ( select the article, and click Request Permissions under Article Tools, or customercare@copyright.com. Reprints: For commercial reprints and all quantities of 500 or more, reprintsolutions@wolterskluwer.com. For quantities of 500 or under, reprints@lww.com, call , or fax EDITOR: Robert E. Campbell, MD, Clinical Professor of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania EDITORIAL BOARD: Teresita L. Angtuaco, MD George S. Bisset III, MD William G. Bradley Jr., MD, PhD Liem T. Bui-Mansfield, MD Valerie P. Jackson, MD Bruce L. McClennan, MD Johnny U. V. Monu, MBBS, Msc Pablo R. Ros, MD, MPH, PhD William M. Thompson, MD Opinions expressed do not necessarily reflect the views of the Publisher, Editor, or Editorial Board. A mention of products or services does not constitute endorsement. All comments are for general guidance only; professional counsel should be sought for specific situations. Indexed by Bio-Science Information Services.

3 concave, smooth, and intact. Disruption may imply fracture or abnormal alignment from ligamentous injury and always should prompt further careful evaluation. Although much attention is given to the carpal bones, the distal radius and ulna and the soft tissues are key components of the wrist, and they must be evaluated during interpretation of radiographs of the wrist. Evaluation of the distal radius includes the radial inclination angle, radial length, and dorsal or volar tilt. The radial inclination angle is the relationship between the radial articular surface and a line perpendicular to the long axis of the radius on the PA view. Normal radial inclination angles range between 13 and 30 degrees, with an average of 22 degrees. The radial length is the distance on the PA view between a line perpendicular to the long axis of the radius intersecting the tip of the radial styloid and a line perpendicular to the long axis of the radius intersecting the articular surface of the ulnar head. Normal measurements range between 11 and 22 mm. On the lateral view, the dorsal or volar tilt is the angle between the articular surface of the distal radius and a line drawn perpendicular to the long axis of the radius. It should range from 11 degrees volar to 4 degrees dorsal tilt. 1,5 These relationships may be disrupted with distal radius fractures, and alterations can result in abnormal loads across the wrist, leading to further long-term morbidity if not corrected. Key soft tissue fat planes include the scaphoid fat stripe (Figure 1A), which is bounded by the radial collateral ligament, abductor pollicis longus tendon, and extensor pollicis brevis tendon; and the pronator quadratus fat stripe (Figure 1B), which is located volar to the pronator quadratus muscle. 1 Displacement of either fat stripe suggests underlying hematoma attributable to a radiographically occult fracture, which is discussed in further detail later. Injury Patterns of the Wrist Predictable injury patterns of the wrist have been derived from cadaver studies through a zone of vulnerability Figure 3. Oblique view of the wrist in a trauma patient reveals a small osseous fragment next to the ulnar styloid process with an associated lunate dislocation (arrowhead) and a proximal hamate fracture (arrow) (confirmed on additional views and CT, not shown), indicating a greater arc injury pattern. delineated by greater and lesser arcs 6,7 (Figure 2). Greater arc injuries typically involve a perilunate dislocation and carpal fracture, the most common being a scaphoid fracture with perilunate instability. More severe injury can result in capitate, hamate, or triquetral fractures along the greater arc (Figure 3). Conversely, lesser arc injuries describe progressive stages of ligamentous injury, which result in rotatory subluxation of the scaphoid and eventually perilunate/ lunate dislocations. 6 Familiarity with injury patterns of the wrist can prompt a search for associated injuries, which are often subtle, can be missed easily, and are clinically important to prevent progressive instability of the wrist. Greater arc wrist injuries typically involve a perilunate dislocation and carpal fracture, usually the scaphoid. Figure 2. PA view of the wrist shows the greater arc (dotted line) and lesser arc (solid line) of injury and the zone of vulnerability (blue shaded area). Systematic Checklist Approach to Evaluation of Wrist Radiographs In our opinion, a systematic checklist approach is essential to avoid errors when interpreting wrist radiographs. We provide a simple yet thorough checklist for use and review each component subsequently (Table 1). Frontal View White Cortical Line Outlining All Bones. On every wrist radiograph, the white cortical margins of the carpal bones, proximal metacarpals, and distal radius and ulna should be scrutinized for evidence of disruption. Disruption of the cortical white line is due most commonly to fracture, followed by erosions from arthritis (Figure 4). Less common causes include neoplasm and infection. Loss of the cortical white line also may indicate carpal coalition. The most common 3

4 Table 1. Radiographic Evaluation of the Wrist Assessment Characteristics PA or AP view Joints Distal radioulnar joint Radiocarpal joint Carpometacarpal joint (lazy M ) Carpal arcs are smooth and concave Contour of the ulna parallels the contour of the radius Cortical rim of hook of hamate should be visible Ulnar variance Positive ulnar impaction syndrome Negative Kienbock disease Lateral view Metacarpal alignment Capitate, lunate, radius align Capitolunate and scapholunate angles Contour of the ulna parallels the contour of the radius Soft tissue assessment Fat stripes (i.e., scaphoid and pronator quadratus) Masses Cortical white line outlining all bones type of isolated carpal coalition is lunotriquetral, which is seen in 0.1% to 1.6% of the population. 8 Carpal coalitions are commonly bilateral, and osseous fusions are much more common than fibrous fusions, which can be symptomatic. Typically, congenital fusions (e.g., arthrogryposis) involve bones from the same carpal row, and syndrome-related fusions (e.g., Ellis-van Creveld syndrome, Holt-Oram syndrome, and Turner syndrome) affect bones from different rows (proximal and distal). 8 On radiographs, loss of the cortical white line of a wrist bone most commonly is attributable to fracture, followed by erosions from arthritis. Joints. The frontal view of the wrist allows for the best evaluation of the wrist articulations, including the distal radioulnar joint, the radiocarpal joint, and the carpometacarpal joints. Assessment of all joints should include alignment and the preservation of joint spaces and smooth articular surfaces. The carpal arcs of Gilula should be intact, and the normal lazy M contour of the carpometacarpal joints should be present (Figure 1A). Disruption of the arcs of Gilula or the lazy M can occur from fracture, dislocation, or both (Figures 5A and 5B). Contour of Ulna Parallels Contour of Radius. On PA and lateral radiographs, the contour of the ulna should parallel the contour of the radius. Disruption of this relationship can signify fracture or dislocation. This is especially important in the pediatric population, as subtle cortical irregularity may indicate a buckle fracture (Figure 6). Cortical Rim of Hook of Hamate Should Be Visible.The white cortical rim of the hook of the hamate deserves special attention. It always should be visible on the frontal view Figure 4. PA view of the wrist demonstrates disruption of the cortical white line (arrow) of the radial articular surface, indicating an intra-articular fracture of the distal radius. (Figure 1A), and disruption implies fracture (most common) or destruction from infection or tumor (uncommon). Hook of hamate fractures occur with a fall on a dorsiflexed wrist, which results in force transmitted through the transverse carpal and pisohamate ligaments 9 (Figure 7). These hook of hamate fractures also are associated with sports that use golf clubs, racquets, or bats. Complications include nonunion, osteonecrosis, injury to ulnar or median nerve, tenosynovitis, tendon rupture, or chronic pain. An important differential diagnosis is a bipartite hook of hamate (i.e., os hamuli proprium), which may mimic a fracture. 9 Hook of hamate fractures occur with a fall on the dorsiflexed wrist; and they also are associated with sports that use golf clubs, racquets, or bats. Ulnar Variance. The last osseous evaluation on the checklist for PA or AP views of the wrist is ulnar variance. The ulna and radius should align when the wrist is in the neutral position; however, some anatomic variation occurs, and the ulna may be longer or shorter than the radius. When the discrepancy between the lengths is greater than 2 mm, there is a predisposition to pathologic processes. 10 Positive ulnar variance occurs when the ulna is longer than the radius, and negative ulnar variance occurs when the ulna is shorter than the radius. Positive ulnar variance may result in ulnar impaction of the lunate and can lead to early degenerative or cystic change in the lunate, termed ulnar abutment syndrome 8 (Figure 8A). Positive ulnar variance also may be associated with triangular fibrocartilage tear. In the setting of negative 4

5 A B Figure 5. A: PA view of the wrist reveals disruption of the lazy M (dotted line) secondary to acute traumatic dorsal carpometacarpal dislocations. Also note the fi fth metacarpal fracture (arrowhead). B: Lateral view of the wrist confirms the dorsal carpo meta carpal dislocation (arrow). ulnar variance, the lunate is predisposed to avascular necrosis or Kienbock disease 11 (Figure 8B). Positive ulnar variance occurs when the ulna is longer than the radius; negative variance when the ulna is shorter. Capitolunate and Scapholunate Angles. As part of the lateral wrist radiographic analysis, the capitolunate and scapholunate angles should be evaluated. The capitolunate angle is formed by two lines drawn along the long axis and Lateral View. Evaluation of the lateral wrist radiograph can be technically challenging secondary to multiple overlying osseous structures; however, a few key points need to be evaluated on every lateral wrist radiograph. Metacarpals, Carpals, and Radius Alignment. On the lateral radiograph, the third metacarpal, capitate, lunate, and radius all should align. Disruption of the alignment of these key components is indicative of an underlying dislocation and possible carpal instability. Figure 6. PA view of the wrist of a skeletally immature patient with arm pain after a fall shows buckle fractures of the distal radius and ulnar metadiaphysis (arrows). Note the loss of parallelism between the ulna and radius. Figure 7. PA view of the wrist shows disruption of the cortical white line of the hook of the hamate (arrow) in this patient who fell on an outstretched hand. A hook of hamate fracture was confi rmed on CT (not shown). 5

6 A B Figure 8. A: PA view of the wrist shows positive ulnar variance (dashed line) with cystic change in the ulnar base of the lunate (dashed arrow), suggesting ulnar abutment syndrome because of impaction on the lunate. B: PA view of the wrist shows negative ulnar variance (straight line) and sclerosis of the lunate (arrow), consistent with avascular necrosis or Kienbock disease. through the center of the capitate and lunate. Similarly, the scapholunate angle is formed by two lines drawn along the long axis and through the center of the scaphoid and lunate. The normal capitolunate angle measures 0 to 30 degrees, and the normal scapholunate angle measures 30 to 60 degrees. 1 Abnormal angles are important secondary signs for intercarpal ligamentous injury and intercalated segment instability, which can lead to advanced instability and destruction of the wrist (Figure 9). The lunate is attached to the scaphoid and triquetrum by the scapholunate and lunotriquetral ligaments, respectively. Tilting of the lunate is determined by the intrinsic ligaments, with the tendency of the scaphoid for volar tilt and the triquetrum for dorsal tilt. If both scapholunate and lunotriquetral ligaments are intact, the lunate is in neutral position because the scaphoid and triquetral actions counteract each other. When there is a scapholunate ligament tear, the scaphoid rotates volarly, causing rotatory subluxation of the scaphoid. Eventually, the lunate tilts dorsally because of the action of the triquetrum, resulting in dorsal intercalated segmental instability. Conversely, when the lunotriquetral ligament is torn, the lunate tilts volarly after the scaphoid, resulting in volar intercalated segmental instability. When both intrinsic ligaments are torn, the lunate becomes unstable, leading to lunate dislocation. Table 2 provides a summary of the most common patterns and associated ligamentous injuries. 1,9 Contour of Ulna Parallels Contour of Radius. As seen on the frontal view, the contours of the radius and ulna should parallel each other. Proper alignment on the lateral view is crucial, and disruption of this relationship can signify fracture or dislocation (Figure 10). Fat Stripes. The last check of every wrist radiograph should be a soft tissue assessment to include evaluation of the scaphoid and pronator quadratus fat stripes. Obliteration, displacement, or irregularity of normal fat stripes is an important 6 secondary sign of a potentially radiographically occult wrist fracture Mass. Hand masses are common, and radiography frequently is performed as an early step in assessment. Although radiographs are often negative in this setting, important information can be gained from radiography. Therefore, systematic Figure 9. Lateral view of the wrist demonstrates an increased capitolunate angle (CLA, 40 degrees) and volar tilt of the lunate in a patient with volar intercalated segmental instability.

7 Table 2. Patterns of Carpal Instability Type SLA, Degrees CLA, Degrees Ligament Normal RSS >60 <30 SLL tear DISI >60 >30 SLL tear VISI <30 >30 LTL tear CLA, capitolunate angle; DISI, dorsal intercalated segmental instability; LTL, lunotriquetral ligament; RSS, rotary subluxation of the scaphoid; SLA, scapholunate angle; SLL, scapholunate ligament; VISI, volar intercalated segmental instability. evaluation of the soft tissues should include soft tissue density, mass effect, calcifications, and pressure erosion on adjacent bone (Figure 11). The presence of any one of these may prompt further analysis with MRI, as the differential diagnosis for a hand mass is broad and includes but is not limited to giant cell tumors of tendon sheath; fibromatosis; lipomas; benign nerve sheath tumors; and pseudotumors such as ganglions, De Quervain tenosynovitis, tophaceous gout or pseudogout, and hydroxyapatite deposition. 15 Conclusion The anatomy of the wrist is complex; therefore, a systematic approach to radiographic interpretation is essential. This Figure 11. PA view of the wrist shows a punctate calcifi cation (arrow) adjacent to the base of the first phalanx, with surrounding increased soft tissue density. A vascular malformation was confi rmed on MRI (not shown). article provides a simple yet thorough checklist for radiographic evaluation of the wrist. This CME activity emphasizes that use of a checklist approach and familiarity with injury patterns may aid in detecting direct and indirect radiographic signs of wrist injury, which can otherwise be difficult to diagnose. Figure 10. Lateral view of the wrist shows dorsal dislocation of the ulna as seen in Essex-Lopresti fracture dislocation. See Figure 1B for normal lateral appearance of the wrist. References 1. Weisman BN, Sledge CB. The wrist. Orthopedic Radiology. Philadelphia, PA: Saunders; 1986: Yin Y, Mann FA, Gilula LA. Positions and techniques. In: Gilula LA, Yin Y, eds. Imaging of the Wrist and Hand. Philadelphia, PA: WB Saunders Co; 1996: Sartoris D, Resnick D. Plain film radiography: routine and specialized techniques and projections. In: Resnick D, ed. Diagnosis of Bone and Joint Disorders, Vol 1. 4th ed. Philadelphia, PA: Saunders; 2002: Gilula LA. Carpal injuries: analytic approach and case exercises. AJR Am J Roentgenol. 1979;133: Novotny SR, Lichtman DM. Distal radius malunion. In: Lichtman DM, Alexander AH, eds. The Wrist and Its Disorders. 2nd ed. Philadelphia, PA: Saunders; 1997: Yeager BA, Dalinka MK. Radiology of trauma to the wrist: dislocations, fracture dislocations, and instability patterns. Skeletal Radiol. 1985;13: Johnson RP. The acutely injured wrist and its residuals. Clin Orthop. 1980;149: Resnick D. Additional congenital or heritable anomalies and syndromes. In: Resnick D, ed. Diagnosis of Bone and Joint Disorders, Vol 5. 4th ed. Philadelphia, PA: Saunders; 2002: Resnick D. Physical injury: extraspinal sites. In: Resnick D, ed. Diagnosis of Bone and Joint Disorders, Vol 3. 4th ed. Philadelphia, PA: Saunders; 2002: Cerezal L, del Pinal F, Abascal F, et al. Imaging findings in ulnar-sided wrist impaction syndromes. Radiographics. 2002;22: Kienböck R. Concerning traumatic malacia of the lunate and its consequences: degeneration and compression fractures. Clin Orthop. 1980;149: Curtis DJ. Injuries of the wrist: an approach to diagnosis. Radiol Clin North Am. 1981;19: Terry DW, Ramin JE. The navicular fat stripe: a useful Roentgen feature for evaluating wrist trauma. Am J Roentgenol Radium Ther Nucl Med. 1975; 124: Moosikasuwan JB. The pronator quadratus sign. Radiology. 2007;244: Teh J, Whiteley G. MRI of soft tissue masses of the hand and wrist. Br J Radiol. 2007;80:

8 CME QUIZ: VOLUME 38, NUMBER 20 To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. Select the best answer and use a blue or black pen to completely fill in the corresponding box on the enclosed answer form. Please indicate any name and address changes directly on the answer form. If your name and address do not appear on the answer form, please print that information in the blank space at the top left of the page. Make a photocopy of the completed answer form for your own files and mail the original answer form in the enclosed postage-paid business reply envelope. Only two entries will be considered for credit. Your answer form must be received by Lippincott CME Institute, Inc., by September 29, At the end of each quarter, all CME participants will receive individual issue certificates for their CME participation in that quarter. These individual certificates will include your name, the publication title, the volume number, the issue number, the article title, your participation date, the AMA credit awarded, and any subcategory credit earned (if applicable). For more information, call (800) All CME credit earned via Contemporary Diagnostic Radiology will apply toward continuous certification requirements. ABR continuous certification requires 75 CME credits every 3 years, at least 25 of which must be self-assessment CME (SA-CME) credits. All SAM credits earned via Contemporary Diagnostic Radiology are now equivalent to SA-CME credits ( Online quiz instructions: To take the quiz online, log on to your account at and click on the CME tab at the top of the page. Then click on Access the CME activity for this newsletter, which will take you to the log-in page for Enter your username and password. Follow the instructions on the site. You may print your official certificate immediately. Please note: Lippincott CME Institute will not mail certificates to online participants. Online quizzes expire on the due date. All questions are ABR Self-Assessment Module (SAM) questions. Participants can claim credit for the SAM regardless of the test outcome. Notify the ABR of the SAM completion, or visit the ABR website at to set up or log in to your personal database to record the number of SAMs you completed. Because CDR has been granted Deemed Status by the ABR, there will no longer be SAM ID numbers printed on the CME certificate. You may contact a MOC specialist at the ABR office by calling A fracture of which one of the following carpal bones is associated most often with a traumatic perilunate dislocation? A. Lunate B. Pisiform C. Hamate D. Scaphoid E. Triquetrum See Reference No. 6 for further study 2. Fractures of the hook of the hamate are least likely to occur in which one of the following athletes? A. Baseball hitter B. Recreational swimmer C. Golfer D. Tennis player E. Cricketer See Reference No. 9 for further study 3. Which one of the following carpal bones is at risk for ulnar impaction in the presence of positive ulnar variance? A. Pisiform B. Scaphoid C. Lunate D. Triquetrum E. Capitate See Reference No. 8 for further study 4. Which of the following carpal bones are involved in the most common carpal coalition in the wrist? A. Lunate, scaphoid B. Lunate, capitate C. Triquetrum, pisiform D. Lunate, triquetrum E. Capitate, hamate See Reference No. 8 for further study 5. All of the following carpal bones at the wrist articulate with the triquetrum, except A. pisiform B. capitate C. lunate D. hamate See Reference No. 4 for further study 6. Which one of the following carpal bones is involved with Kienbock disease? A. Hamate B. Capitate C. Scaphoid D. Trapezium E. Lunate See Reference No. 11 for further study 7. Which one of the following ligaments is torn in a DISI pattern of instability? A. Scaphocapitate B. Lunotriquetral C. Scapholunate D. Ulnolunate E. Radiotriquetral See Reference No. 1 for further study 8. The PA radiograph of a young boy with a painful wrist after a fall reveals loss of parallelism and irregular metadiaphyseal cortical bulging of the distal ulna and radius. The most likely diagnosis is A. buckle fractures of the radius and ulna B. plastic bowing fractures of the radius and ulna C. physeal fractures of the radius and ulna D. complete, undisplaced fractures of the radius and ulna E. normal distal radius and ulna See Reference No. 7 for further study 9. Initial imaging of the traumatized wrist comprises A. CT B. radiography C. MRI D. ultrasound E. bone scintigraphy See Reference No. 3 for further study 10. All of the following are part of systemic checklist radiographic evaluation of the injured wrist, except A. intact cortical white line outlining all bones B. contour of distal ulna parallels contour of distal radius C. capitate, lunate, and distal radius align on the lateral view D. scaphoid and pronator quadratus fat stripes E. normal convexity of the carpal arcs See Reference No. 12 for further study 8