ARRS 2022 Abstracts

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E1385. Carpal Dislocations and Fracture-Dislocations: An Anatomic and Diagnostic Review
Authors
  1. John Shields; University at Buffalo
  2. Jacob Chenez; University at Buffalo
  3. Jason Ciotola-Koch; University at Buffalo
  4. Thomas Bevilacqua; University at Buffalo
Background
Carpal dislocations, while a relatively uncommon diagnosis, are missed either clinically or radiographically on initial presentation in up to 25% of cases. The diagnosis is usually made with radiography, and CT plays a complimentary role and often identifies radiographically occult associated fractures. These injuries most commonly affect young male adults secondary to high-energy trauma involving a fall on an outstretched hand with axial loading. Early identification and proper management are essential, and delayed treatment can lead to poorer outcomes including secondary osteoarthritis, median nerve injury, and carpal instability. Therefore, it is crucial for the radiologist to be familiar with the underlying normal osseous and ligamentous anatomy including zones of vulnerability along the carpal arcs and the unique nomenclature of carpal fracture-dislocations to ensure accurate and timely diagnosis of these injuries.

Educational Goals / Teaching Points
The initial goal is to review the normal osseous and ligamentous anatomy of the wrist, focusing primarily on the ligaments that provide support to the lunate. Next, a discussion of the “zones of vulnerability” along the lesser and greater arcs as well as the stepwise progression of carpal dislocations will provide further foundation. Using this framework as a guide, the next goal is a clear demonstration of the classic radiologic findings of carpal dislocation and fracture-dislocations. Clinical examples and multimodality imaging with an emphasis on radiography and CT will elucidate the mechanism and progression of these injuries as described by the Mayfield classification system. Finally, the routine management of these injuries will be reviewed to highlight the importance of prompt diagnosis and treatment.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Carpal dislocations predominately involve the lunate and occur secondary to disruption of the surrounding intrinsic and extrinsic ligaments in a progressive, stepwise manner. Understanding the underlying anatomy is paramount to understanding the mechanism of injury and radiographic findings. The Mayfield Classification will be outlined to describe the four stages of ligamentous injury that lead to scapholunate ligament injury, perilunate dislocation, midcarpal dislocation, and lunate dislocation. A brief review of the unique nomenclature of perilunate fracture-dislocations, such as a trans-scaphoid perilunate dislocation, will be included. Plain radiographs can be used to diagnose carpal dislocations and most associated fractures. CT imaging can help characterize these fractures and can identify additional radiographically occult fractures.

Conclusion
Carpal dislocations are often missed injuries that require timely diagnosis and treatment. These injuries exist on a spectrum, occurring in a progressive manner depending on which ligament is disrupted. Familiarity with the underlying anatomy and radiographic findings is crucial for the radiologist to improve patient care. This exhibit will provide an anatomic review and multimodality approach to the diagnosis these injuries.