Fractures of the hook of the hamate--a failure of clinical diagnosis.

Two cases of a fracture of the hook of the hamate are described in which the diagnosis was clinically missed even though a fracture of the hook was considered. In one patient, the clinical diagnosis was thought to be ulnar wrist instability, and in the other, a pisiotriquetral injury. In one case, the diagnosis was confirmed only by a computerized tomography scan even though lateral tomograms were negative.