Injury (1985) zyxwvutsrqpo 16.307-308 Printed in Great Britain 307 Isolated traumatic posterior dislocation of the radial head-a case report J. FL Jones and S. G. T. Smith Northwick Park Hospital and Clinical Research Centre, Harrow, Middlesex INTRODUCTION ISOLATED dislocation of the radial head in an adult is extremely rare, and some authorities doubt that this injury can occur without an associated fracture of the ulna (Watson-Jones, 1982). Only one previous case of an isolated posterior dislocation of the radial head in an adult has been reported in the literature (Heidt and Stern, 1982). CASE REPORT A 26-year-old Caucasian male injured his left arm playing rugby. He received a blow on the forearm while tackling an opponent around the legs. His left elbow was almost fully extended, with the forearm in about mid-rotation at the time of the injury. He experienced pain in the forearm and elbow following the tackle, with reduction of elbow movements. On examination in the Accident Department, there was an obvious swelling on the posterolateral aspect of the elbow. There was no tenderness in the remainder of the elbow or forearm. The elbow was held in about 60” of Hexion and 10” of supination. There was no sign of damage to nerves. X-ray films of the elbow (Fig. 1) and whole forearm (Fig. 2) showed a h Fig. 2. Anteroposterior (a) and lateral (b) radiographs of the whole forearm demonstrating that the shaft of the ulna is intact. a b Fig. 1. Anteroposterior (a) and lateral (b) radiographs of the left elbow showing posterior dislocation of the radial head. an isolated posterior dislocation of the radial head, which was normal in appearance. Spontaneous reduction of this dislocation occurred as the patient’s elbow was lifted, producing increased pronation. Further X-ray films (Fig. 3) confirmed reduction and demon- strated an avulsion fracture at the site of attachment of the annular ligament to the coronoid process of the ulna. A plaster-of-Paris backsplint was applied with the elbow at W and the forearm in mid-rotation. This splintage was continued for 3 weeks. At 2% months, a full range of painless movement had been regained, and there was no instability.