Congenital unilateral dislocation of the radial head.

Congenital dislocation of the radial head is a well-recognized entity occurring either as an isolated abnormality or in association with multiple syndromes. Bilaterality has been a criterion for diagnosis of an isolated congenital dislocation of the radial head, with unilaterality regarded as an acquired lesion. A retrospective review of isolated unilateral dislocations of the radial head was undertaken. Six patients were identified with histories that dated back to early infancy in five of the six patients. We believe that this series, coupled with results of previous embryologic studies, confirms the existence of a unilateral congenital dislocation of the radial head.