Dislocation and fracture-dislocation of the carpometacarpal joints

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 injury is a coronal hamate fracture with dislocation of the 4th and/or 5th CMC joint.

If the 3rd CMC joint is involved too, then usually the capitate is also fractured.

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

CT scans are helpful to evaluate the size, shape, and pattern of an associated fracture.

This case shows a dislocation of the 5th CMC joint before and after reduction.