Palmar dislocation in the metacarpophalangeal joint of the thumb--a case report.

A 19-year-old male sustained forced hyperflexion of his right thumb in a motorcycle accident which resulted in a palmar dislocation of the metacarpophalangeal joint. Open reduction was performed which confirmed the rupture of the palmar plate. Dislocation recurred post-operatively. A second operation was carried out, at which time rupture of the radial collateral ligament and dorsal capsule was recognised. Postoperative joint movement was within an acceptable range. However, radiographic examination revealed persistent subluxation. This result was thought to be related to the shape of the head of the first metacarpal bone.