Chronic, complex volar dislocation of the metacarpophalangeal joint.

Three cases of traumatic volar dislocation of the metacarpophalangeal (MP) joint of a finger had a common pathologic condition, interposition of the dorsal capsule within the joint space. Late treatment included open reduction. MP joints arthrodesis, or arthroplasty. We reproduced volar dislocation of the MP joint in cadaver specimens by a hyperflexion, proximal translational force applied to the dorsum of the proximal phalanx. In all dislocations, the dorsal capsule of the joint was avulsed proximally and drawn into the joint. Dorsal capsule entrapment may be an important pathologic feature militating against successful closed management in a significant percentage of these injuries. A dorsal surgical approach with reduction and repair is recommended when the injury is seen before onset of gross degenerative changes within the MP joint.