Habitual volar dislocation of the ulnar head with a locked distal radioulnar joint after distal radius fracture: A case report.

RATIONALE Habitual volar dislocation of the ulnar head with a locked distal radioulnar joint (DRUJ) is a rare complication after distal radius fracture. We present a case of habitual volar dislocation of the ulnar head in a woman with a dorsally displaced malunited distal radius fracture. PATIENT CONCERNS A 72-year-old woman presented with occasional painful locking of the forearm in full supination. She had fractured the left distal radius in a fall 6 months previously. The fracture had been treated non-surgically with wrist immobilization in a long and short arm cast for 6 weeks. Physical examination showed no swelling of the left hand. The wrist locked when the forearm was fully supinated, and the patient was not able to pronate her forearm without reducing the ulna by pressing the left ulna down toward the DRUJ. She experienced sharp pain during the reduction procedure and pronation of the left forearm. The affected wrist had 91% motion compared with the contralateral wrist. DIAGNOSIS Radiography and computed tomography showed 28° dorsally angulated malunion of the distal radius and ulnar head subluxation with respect to the radius. Magnetic resonance imaging revealed disruption of the ulnar-side triangular fibrocartilage complex (TFCC) from the ulna fovea. INTERVENTIONS The patient desired surgery to address the painful click during full supination of her left wrist and the limitations in her activities of daily living. Corrective osteotomy of the distal radius and arthroscopic repair of the ulnar-side tear of the TFCC were performed. The TFCC was arthroscopically repaired to the ulnar fovea to stabilize the DRUJ. OUTCOMES At 1 year postoperatively, radiography showed complete union of the radius. The affected side had 97% wrist motion compared with the contralateral wrist and a full range of forearm rotation without pain or clicking. The grasp strength was 100% compared with the normal wrist. LESSONS Malunited distal radius fracture with concomitant TFCC injury can result in habitual volar dislocation of the ulnar head due to severely dorsally angulated malunion of the radius and avulsion of the ulnar-side TFCC from the ulna fovea. This condition required corrective osteotomy plus TFCC repair.