Isolated fracture-dislocation of the fourth carpometacarpal joint. A report of two cases.

Dislocations and fracture-dislocations of isolated and multiple carpometacarpal (CMC) joints are rare injuries that usually result from the impact of a clenched hand on an immobile object. Various authors have presented combinations of dislocations of any or all of the CMC joints. Isolated fracture-dislocation of the fourth CMC joint, however, is either exceedingly rare or highly underreported. Two cases of isolated fracture-dislocation of the fourth CMC joint are presented here: in both, the appearance of the hand suggested a fracture-dislocation of the CMC joint, and the isolated lesion was confirmed at the time of surgery. Both patients were treated with open reduction and internal fixation and had good results at 2 years.