Idiopathic distal radioulnar synostosis.

Radioulnar synostosis is rare, and exists in two forms: congenital and post-traumatic. The congenital form presents only in the proximal forearm, and the post-traumatic form may present anywhere along the radius and ulna. The only known aetiology for distal radioulnar synostosis is post-traumatic. We present a rare case of distal radioulnar synostosis with no previous history of trauma.