Middle PhaLanx

We report a patient with an irreducible d s ocation of the proximal interphalangeal joint which was due to entrapment of the head of the proximal phalanx in the opening of the flexor digitorum superficialis tendon just proximal to its chiasma. Journal of Hand Surgery (British and European Volume, 1998) 23B::252 Dislocations of the proximal interphalangeal joint of the hand are relatively common injuries and can usually be reduced in a closed fashion. Occasionally, however, a closed reduction may be unsuccessful due to soft tissue interposi-tion. The structures which have been implicated are: ten-dons (Selig and Schein, 1940); the palmar plate (Oni, 1985); the lateral band (Johnson and Greene, 1966); the head of the proximal phalanx (Moberg, 1960); and the articular cartilage (Whipple et al, 1980). This case report describes yet another possible cause of failure of reduction: button-hole entrapment of the proximal phalangeal head in the opening of the flexor digitorum superficialis tendon. Case report A 30-year-old man fell and sustained a hyperextension injury to the right index finger. On clinical examination, a 2.5 cm palmar laceration was found, extending from the radial aspect of the PIP joint to the ulnar aspect of the MCP joint. The head of the proximal phalanx pro-truded from the wound. Radiographs revealed a dorsal dislocation of the PIP joint without fracture. At operation, the wound was extended, rbrided, and copiously irrigated. Reduction was attempted next but this was unsuccessful. It was then noted that the head of the proximal phalanx had buttonholed through the open-ing in the FDS tendon (Fig 1). The palmar plate was also noted to have been avulsed from the proximal phalanx. The proximal phalangeal head was pushed back through the FDS tendon and reduced. The palmar plate was then repaired. After reduction, a dorsal splint was applied. Range of motion exercises were started after 3 weeks. Three months postoperatively, the active range of motion of the PIP joint was 10 ° to 80 ° and the jointwas table