Imaging of Carpal Instabilities

Abstract

Background The term “carpal instability” describes different debilitating wrist conditions, in which the carpus is unable to maintain its physiological range of motion and load transfer. Depending on the cause and location of the dysfunction, four groups can be defined: dissociative, non-dissociative, complex, and adaptive carpal instability. As the most common form by far, dissociative carpal instability can further be categorized as dorsal or palmar intercalated segment instability, contingent on the afflicted interosseous ligament. Method This review article outlines the different entities of carpal instability, their pathophysiology, and their clinical presentation. It further discusses the diagnostic significance of different imaging methods as well as the established treatment options for each form of instability in context with the current literature. Results and Conclusion Early detection and treatment of carpal instability are essential for preventing carpal osteoarthritis. Traumatic lesions of the scapholunate interosseous ligament are the most frequent cause of instability. They can occur in an isolated fashion or in context with other carpal injuries. While stress imaging and fluoroscopy facilitate the differentiation between dynamic and static forms of carpal instability, only MRI and CT/MR arthrography can directly reveal the extent of ligament discontinuity. Key Points: Citation Format

Carpal Instability: I. Pathoanatomy

“…It leads to malalignment of the proximal carpal row either during motion ("dynamic") or at rest ("static"). 4,19,35,36…”

“…Displacement of the proximal carpal row can become apparent either during movement (dynamic CIND) or at rest (static CIND). 35,36,44…”

“…It is marked by dislocation of the capitate head from the articular cavity of the lunate during motion while the other carpal bones maintain a normal movement pattern. 36,54 The Complex and Axial Forms of Carpal Instability…”

“…The most common cause of dorsal wrist dislocation is the dorsally angulated articular surface of the radius, found in dorsal rim fractures (Barton's fractures) or malunited radius fractures. 36,47,48 Such a radiocarpal joint deformity can cause two forms of carpal instability. In the first case (►Fig.…”

Extrinsic and Intrinsic Ligaments of the Wrist

“…It can be categorized as dorsal intercalated segment instability (DISI) or palmar/volar (PISI/VISI), depending on the affected interosseous SL or LT ligament; VISI and LT dissociation are more rarely encountered. 2,9,10 Nondissociative carpal instability (CIND) is defined as articular dysfunction between the proximal carpal row and the forearm (RC instability) or between the proximal row and the distal row (midcarpal instability). The proximal carpal row remains intact but is either incorrectly aligned with the distal carpal row or dislocated from the forearm.…”