Divergent fracture-dislocation of the hamatometacarpal joint: case report.

Hamatometacarpal fracture-dislocation is a rare injury that consists of a fourth metacarpal fracture and a fifth carpometacarpal joint injury. We present the case of a 21-year-old man with a divergent hamatometacarpal fracture-dislocation that consisted of a combination of dorsal intra-articular fracture-dislocation of the fourth carpometacarpal joint, palmar dislocation of the fifth carpometacarpal joint, and fracture of the hook of the hamate. The mechanism of palmar dislocation of the fifth metacarpal base and fracture of the hook of the hamate involved extension of the fifth metacarpal and ulnopalmar load transmission.