Injuries to the ulnar carpometacarpal region: are they being underdiagnosed?

Thirteen cases with radiographic evidence of injury to the ulnar side of the hand are reviewed. These injuries included intraarticular fractures and/or dislocations of the fourth and fifth carpometacarpal joints and associated bones collectively discussed here as the ulnar carpometacarpal region. In nine the extent of the injury was not appreciated on first presentation. Injuries to this region are often difficult to assess clinically and radiographically even in experienced hands. In our experience computerized tomography (CT) scans in the longitudinal and longitudinal oblique axis best display the ulnar carpometacarpal joint surfaces and their relationship to each other. We recommend CT of the ulnar carpometacarpal region where clinical evidence of an injury to this region is not in keeping with the plain radiographic findings, and when planning surgery on a complex injury in this region.