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Division of Plastic and Reconstructive Surgery, University of Toronto, St Joseph’s Health Centre, Toronto, Ontario Correspondence: Dr Kyle Wanzel, Division of Plastic and Reconstructive Surgery, St Joseph’s Health Centre, Suite 707, 1243 Islington Avenue, Etobicoke, Ontario M8X 1Y9. Telephone 416 236-2571, fax 416-236-4591, e-mail [email protected] Metacarpophalangeal (MP) joint injuries and dislocations of the fingers and thumb are not uncommon (1-8). They can be classified directionally as either being volar or dorsal, although volar dislocations of the thumb MP joint are exceedingly rare (4). Dorsal dislocations are commonly classified with respect to their ease of reduction into three different categories: incomplete, simple complete and complex (4,6). Incomplete dislocations are better described as subluxations because a portion of the joint remains congruous. The collateral ligaments remain intact, the joint is easily reduced and it is stable on postreduction testing. Complete dislocations describe complete disassociation of the joint, and indicate a significant injury or rupture to the volar plate, joint capsule and at least part of the collateral ligaments. In simple complete dislocations, a closed reduction is expected to be relatively easy. In comparison, complex complete dislocations are described as dislocations that are not easily reducible and often require surgical intervention. Failure to achieve a closed reduction is usually due to the interposition of the volar plate, sesamoid bones, bony fracture fragments or the flexor pollicis longus tendon within the MP joint space, precluding its reduction. In a complex complete, irreducible thumb MP joint dislocation, the most common culprit is an entrapped volar plate. It usually ruptures from its weakest proximal attachments to the metacarpal bone, remains attached to the base of the proximal phalanx, and then resides within the joint space trapped between the base of the proximal phalanx and the head of the metacarpal. This hinders the reduction of dislocated joint and necessitates an operative approach (8-19). We present a case of a complex complete, dorsal, thumb MP joint dislocation in a patient presenting two months postinjury. To our knowledge, this is the only case of chronic complex thumb MP joint dislocation that is described in the literature. Case presentation A 48-year-old right-hand-dominant construction worker presented to the plastic surgery outpatient clinic two months after his initial injury. He presented with pain, swelling and essentially no range of motion in his right thumb following a fall on his outstretched hand two months earlier. Initially, he was assessed 24 h postinjury in the emergency department. The initial x-ray at the time of presentation showed a complete dorsal dislocation of the thumb MP joint. At that time, he refused to undergo a closed reduction and a timely referral was then sent to the plastic surgery clinic. He missed multiple scheduled appointments, had no intervention or further investigation, and finally presented at the clinic two months postinjury. At the time of presentation to the clinic, examination revealed the right thumb MP joint to be in slight hyperextension and the interphalangeal joint joint held in mild flexion. There was residual swelling and tenderness mainly involving the MP joint. He had essentially no range of motion in the thumb MP joint. A new x-ray was taken at this time in the clinic, confirming a persistent complete dorsal dislocation of the thumb MP joint (Figure 1). Detailed inspection of the x-ray revealed possible signs of entrapped structures within the joint. The joint space was significantly widened, and it appeared on the lateral x-ray that a sesamoid bone was trapped within the joint space. A single attempt at closed reduction under local anesthesia was attempted but was unsuccessful. Informed consent was obtained and arrangements were then made for an open reduction in the operating room. Under a general anesthetic and muscle relaxation, a final attempt at closed reduction was attempted, but once again, was unsuccessful. Then, under tourniquet control, a dorsal approach to the MP joint was undertaken. A dorsal curvilinear incision was made over the thumb MP joint. The extensor apparatus was split longitudinally, between the cAse report