Wrist instability

Abstract

Hidden in the diagnosis of ‘the sprained wrist’ is the missed ligament tear. A resultant carpal instability pattern can cause persistent pain and late osteoarthritis. The carpal bones act as a link system of two rows between the forearm and hand, held together by both an intrinsic and an extrinsic ligament system. Two common patterns of carpal collapse occur, the first at the scapho-lunate joint, where a tear results in scaphoid flexion and lunate extension (dorsal intercalated segment instability - DISI). The second occurs at the luno-triquetral joint, and results in lunate flexion (volar flexed intercalated segment instability - VISI). Further instability patterns are now emerging; those at the triquetro-hamate joint producing ulnar-sided wrist pain and midcarpal laxity, and complex dislocations, with or without fracture. Careful clinical examination, plain X-rays, magnetic resonance imaging (MRI) scan and wrist arthroscopy can enable a clear diagnosis to be made for most instability patterns. Treatment consists of acute open repair, soft tissue stabilization procedures or limited intercarpal fusion, depending on the time from injury.