Closed ruptures of the extensor pollicis longus tendon usually appear as a consequence of fractures of the wrist joint or ensue from polyarthritic changes or result from a process of degeneration. Mechanical injury of the tendon is quite rare but can be observed after direct trauma or rotational injury.
The patient in the case described was a 19-year-old woman who had not been injured. A slight pain in her right wrist persisted for two weeks and then she was unable to extend her thumb interphalangeal joint. Clinically distinct signs of a rupture of the extensor pollicis longus could be seen.
During the operation a tear of the muscular portion of the extensor pollicis longus was found. The muscle was severely degenerated. It was enclosed in the muscular sheath which was also degenerated. The sheath originated from the same as the extensor pollicis longus and inserted into the dorsal transverse carpal ligament.
The function of extension was restored by transfer of the extensor indicis proprius tendon.
