[Irreducible dislocation of the metacarpophalangeal joint of the index finger].

Complete dorsal dislocation of the metacarpophalangeal joint of the index finger is rare and closed reduction of this peculiar dislocation is usually impossible. The injury is produced by striking of the outstretched index against a resistant object, usually in a fall on the hand. The base of the proximal phalanx is displaced over the dorsum of the metacarpal head. The fibrocartilaginous palmar plate remaining attached to the phalanx, is folded into the joint where it becomes wedged between the metacarpal head and the base of the proximal phalanx. In this type of dislocation closed reduction is unsuccessful. Open reduction should be performed through a palmar incision. Description of a typical case.