The 'mirrored' Bennett fracture of the base of the fifth metacarpal.

Fractures of the base of the metacarpals are usually treated conservatively. The intra-articular fracture of the base of the first metacarpal ('Bennett fracture') is an exception to this rule because inadequate repositioning and fixation of the dislocated radial fragment lead to permanent deformity of the joint and subsequent degenerative joint disease. The dislocated intra-articular fracture of the base of the fifth metacarpal is similar to a Bennett fracture in many aspects. Repositioning of this 'mirrored' Bennett fracture cannot be guaranteed by a plaster cast. Inadequate repositioning will lead to pain, reduced strength and early degenerative joint disease. We present six patients with dislocated intra-articular fractures of the base of the fifth metacarpal to illustrate the necessity of surgical reduction and fixation.