Midcarpal Instability

Midcarpal instability (MCI) was first recognized as a distinct clinical entity toward the end of the twentieth century, long after most other carpal instabilities had been described. As opposed to a longitudinal rent between two carpal bones, MCI is caused by lax intrinsic and extrinsic ligaments crossing the radiocarpal joint. Clinically, this laxity leads to volar capitate subluxation and results in a painful “catch-up” clunk as the wrist is brought from radial into ulnar deviation due to reduction of the volar capitate subluxation. The diagnosis may be confirmed by physical examination utilizing the midcarpal shift test or with live fluoroscopy. In almost all patients, initial management is nonsurgical consisting of anti-inflammatory medications, splinting, and proprioceptive training. In those failing to improve, surgical options include dorsal wrist capsular reefing, thermal capsular shrinkage, or partial wrist arthrodeses. The prognosis for return to sports is good in most cases.