Dislocation and fracture-dislocation of the carpometacarpal joint

Dislocations and fracture-dislocations of the carpometacarpal (CMC) joint often show dorsal dislocation of one or multiple metacarpal bases.

The dislocations are classified by the AO/OTA as 70D2–5[5], where 2–5 indicates the metacarpal involved in the dislocation.

CMC dislocations may be associated with soft-tissue injuries and fractures of the carpal and/or metacarpal bones.

A frequent fracture-dislocation involves a fracture of the 5th metacarpal base, as the extensor carpi ulnaris causes deformity and dislocation of the articular fragment.

X-rays in AP, lateral and oblique views are required.

This case shows a dislocated 5th CMC joint.

Lateral x-rays

CT scans help evaluate the size, shape, and pattern of an associated fracture.