Radioulnar synostosis

Radioulnar synostosis is a rare condition where there is an abnormal connection (synostosis) between the radius and ulna bones of the forearm. This can be present at birth (congenital), when it is a result of a failure of the bones to form separately, or following an injury (post-traumatic).

It typically causes restricted movement of the forearm, in particular rotation (pronation and supination), though is usually not painful unless it causes subluxation of the radial head. It can be associated with dislocation of the radial head which leads to limited elbow extension.