Dorsal carpometacarpal dislocation of the fifth finger: discussion of diagnosis and therapy on two cases

Abstract

Dorsal dislocation of the fifth carpometacarpal joint after injury is rare. Only five cases are reported in the literature. We report on two cases of dorsal dislocation of the fifth carpometacarpal joint after injury and we give a review of related literature. There are two interesting aspects concerning diagnostic and therapy of dorsal dislocation of the fifth carpometacarpal joint. Anterior-posterior and lateral radiographs do not always provide adequate visualisation of this joint so a dislocation may be misdiagnosed. A radiograph taken with the forearm pronated 45 degrees from the routine anterior-posterior position better shows the dislocation. The adequate therapy consists in closed reduction, Kirschner wire fixation and cast immobilisation. A reduction without following Kirschner wire fixation - even in those dislocations that were found to be stable after closed reduction - is not recommended because of the risk of persisting pain after heavy manual work. In our two cases an instability of the fifth carpometacarpal joint existed after closed reduction. After Kirschner wire fixation and cast immobilisation for 6 weeks both patients showed 3 months after operative therapy a full range of movement and a powerful grip without any pain in the fifth carpometacarpal joint.