An anomalous bifid distal ulna: A case report.

We report a case of an osteochondroma in the form of an anomalous bifid distal ulna following mal-union of an epiphyseal injury. There has been no previous case of this reported in the medical literature.A 19-year-old man presented with wrist stiffness and complete loss of pronation and supination twelve months after having undergone open reduction and internal fixation for a volarly displaced distal radius fracture. Further investigation with a CT scan showed a bifid distal ulna. As this was not present on plain radiographs one year prior, it was proposed that this was an osteochrondromatous growth caused by injury to the distal ulnar epiphysis. An operation was performed to excise one of the distal ulna heads, and reconstruct the TFCC to allow improved rotational movements. At one year follow-up, the patient has made an almost full recovery without complication.We postulate that the patient sustained an occult physeal injury resulting in an osteochondromatous lesion that grew towards the joint effectively forming a second ulna head.This is a unique case of the development of a bifid distal ulna due to physeal injury one year prior. Such a lesion has not previously been described in the distal ulna.