Congenital pseudoarthrosis of the ulna

A rare bone development disorder characterized by abnormal bowing of the ulna and subsequent non-healing fracture with formation of a false joint (pseudoarthrosis), instability and angulation at the pseudoarthrosis site, and shortening of the forearm. Additional signs and symptoms include concomitant bowing of the radius, abnormalities of the humeroulnar joint, and limited pronation or supination of the forearm. Neurofibromatosis type 1 and osteofibrous dysplasia are frequently associated.