Late presentation of a complete complex thumb metacarpophalangeal joint dislocation: A case report.

Metacarpophalangeal (MP) joint injuries and dislocations of the fingers and thumb are not uncommon. They can be classified directionally as either being volar or dorsal, and are further categorized as incomplete, simple complete or complex complete. Complex dislocations are described as dislocations that are irreducible and often require surgical intervention. This is often because tissue has become entrapped within the MP joint, precluding its anatomical reduction. For the thumb MP joint, anatomical structures that may become trapped include the volar plate, sesamoid bones, bony fracture fragments or the flexor pollicis longus tendon. Both dorsal and volar surgical approaches have been described, and their relative merits will be discussed. The unusual case of a late presentation (two months postinjury) of a complex complete dorsal dislocation of the thumb MP joint approached from a dorsal incision is presented.