Radial sesamoid displacement of the thumb metacarpophalangeal joint

摘要

We present a case of a 24-year-old man with right thumb metacarpophalangeal (MCP joint locking due to radial sesamoid displacement. The patient presented 5 days following a sports related injury caused by a blow to the palmar aspect of the joint. Examination showed a hyperextension posture of the joint. Both active and passive joint motions were limited and painful. Radiography showed ulnar subluxa-tion of the thumb MCP joint under an interposed radial sesamoid (Figure 1). An attempt at closed reduction of the displaced sesamoid with a digital block failed.