Irreducible epiphyseal plate fracture of the distal ulna due to interposition of the extensor carpi ulnaris tendon. A case report.

It is well known that tendon or muscle interposition can cause fractures to be irreducible by closed means. A rare tendon interposition of extensor carpi ulnaris occurred in an 11-year-old boy. The isolated displaced distal ulnar physeal injury was the result of a motor vehicle accident. Attempts to perform a closed reduction failed. At operation, an interposed extensor carpi ulnaris tendon was found. After repositioning the tendon, a near anatomic reduction was easily accomplished. Only two cases seem to have been reported in the literature on the need for open reduction of distal ulnar physeal injury, none with an interposed tendon. Interposed extensor carpi ulnaris tendon should be considered as a cause of irreducible displaced distal ulna epiphyseal fracture.