Palmar Dislocation of the Trapezoid with Associated Carpometacarpal Injuries: Two Case Reports and Literature Review.

PURPOSE: Palmar dislocation of the trapezoid is an exceptionally rare injury, typically resulting from high-energy wrist trauma, and is frequently associated with complex carpal or carpometacarpal fractures.

MATERIALS AND METHODS: We report 2 cases of palmar trapezoid dislocation following motorcycle accidents. In both patients, the injury was associated with multiple fractures and carpometacarpal dislocations. Open reduction via a dorsal approach with temporary Kirschner-wire fixation and ligamentous repair was performed.

RESULTS: At final follow-up, anatomical reduction was maintained in both cases without radiological signs suggestive of trapezoid avascular necrosis on radiographs and computed tomography. Functional outcomes were influenced by the severity of associated injuries. A review of the literature identified eight previously reported cases, most treated with open reduction via a dorsal approach. Trapezoid excision, described in earlier reports, was associated with less favorable outcomes due to secondary dorsal migration of the second metacarpal.

CONCLUSIONS: Palmar trapezoid dislocation remains difficult to diagnose because of its rarity and frequent association with complex carpometacarpal injuries. Early recognition and open reduction via a dorsal approach allow stabilization of the central column and ligament repair. Trapezoid avascular necrosis is theoretically possible; however, available anatomical and clinical data suggest that it appears to be uncommon. Functional outcomes appear to depend more on the severity of associated carpal and carpometacarpal injuries than on the trapezoid dislocation itself.

TYPE OF STUDY/LEVEL OF EVIDENCE: Case report, level IV.