Abstracts

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E1316. The Enduring Utility of Radiographs: Clues to Diagnosing Soft Tissue Injuries
Authors
  1. Daniel Schneider; University of Michigan
  2. Corrie Yablon; University of Michigan
  3. Kara Gaetke-Udager; University of Michigan
Background
Radiographs are commonly ordered in the setting of injury owing to their accessibility and short examination time. Despite their advantages, radiographs are insensitive for many soft tissue injuries, which comprise a large percentage of musculoskeletal complaints. Soft tissue injuries that are difficult to diagnose or occur infrequently may be overlooked, leading to delayed care and poor outcomes. Fortunately, many radiographic findings can suggest the presence of soft tissue injuries that may otherwise go untreated.

Educational Goals / Teaching Points
This exhibit presents radiographic findings that are associated with specific soft tissue injuries and details the importance of accurate and timely diagnosis of these injuries. We review the correlative cross-sectional imaging for each injury and highlight how radiologists can use knowledge of these radiographic findings to recommend further testing and guide diagnostic work-up.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Cortical irregularity or periarticular avulsion can signal injury to origins and attachments of ligaments and tendons. For example, fragmentation of the medial epicondyle apophysis may occur in adolescents due to repetitive flexor pronator muscle contraction during throwing. Magnetic resonance imaging may be used in these cases to evaluate for flexor pronator and ulnar collateral ligament (UCL) injuries.1 Osseous irregularity at the ulnar base of the thumb proximal phalanx can indicate injury to the UCL, which may occur after falling onto the thumb while holding an object such as a ski pole (“skier’s thumb”).2 We also review the “arcuate sign” (posterolateral corner injury), reverse Segond fracture (posteromedial corner injury), “sliver sign” (lateral patellar dislocation and medial patellofemoral ligament tear), “trough sign” (posterior shoulder dislocation), and triquetrum avulsion (carpal ligament avulsion).3-7 Subtle abnormalities in joint alignment may portend substantial soft tissue injury. The “light bulb sign” denotes a persistently internally rotated humeral head on external rotation and Grashey views of the shoulder in the setting of posterior glenohumeral joint dislocation.8 Narrowing of the subacromial space may be seen with full-thickness rotator cuff tear. Lateral patellar subluxation or tilt may be seen following lateral patellar dislocation. Close scrutiny of common incidental findings is essential. Os peroneum, an accessory ossicle in the distal peroneus longus tendon present in up to 26% of patients, may fracture or retract posteriorly in the setting of peroneus longus tear.9 Attention to muscles within the field of view may also be helpful. In the case of distal biceps tendon rupture, the “Popeye sign” describes the prominent retracted muscle belly sometimes apparent on radiographs.10

Conclusion
While radiography lacks the soft tissue characterization of ultrasound and magnetic resonance imaging, the radiographic findings listed above may indicate specific underlying soft tissue injuries. Understanding the significance of these findings can help radiologists make appropriate recommendations, thereby improving diagnostic accuracy and patient outcomes.