Retrograde intramedullary K-wire fixation of trapezoid dislocation: a case report

Trapezoid dislocations are extremely uncommon injuries because of the strong intercarpal and carpometacarpal ligaments that provide greater stability to the trapezoid-metacarpal joint compared with the more ulnar carpometacarpal joints. We report a case of trapezoid dislocation, emphasizing the radiographic features essential for diagnosis and the fixation strategy used for management. A 50-year-old woman sustained a sliding fall while riding a scooter, resulting in a trapezoid dislocation from the carpometacarpal joint accompanied by a fracture at the base of the right third metacarpal. The injury was managed with retrograde intramedullary K-wire transfixation of the second metacarpal-trapezoid joint combined with a spanning plate across the thrid metacarpal-capitate joint. The spanning plate maintained the length of the third metacarpal relative to the capitate, thereby indirectly restoring the anatomical alignment of the second metacarpal and stabilizing the reduced trapezoid. The retrograde intramedullary K-wire was easily positioned so that its tip did not extend beyond the trapezoid, thus preventing potential irritation of surrounding vital structures that might result from an obliquely placed K-wire. The 'missing carpal sign' serves as an important radiographic clue suggestive of trapezoid dislocation. Given the strong surrounding interosseous ligaments, it is important to recognize the possible occurrence of trapezoid dislocation in association with fractures or dislocations involving structures adjacent to the trapezoid. We present a retrograde intramedullary K-wire fixation technique for stabilizing the trapezoid-metacarpal joint, which can be easily and effectively applied after anatomical reduction of the trapezoid.