Traumatic rupture of the extensor pollicis longus tendon.

Rupture of the extensor pollicis longus tendon is rather rare, attributable in about half of all cases to rheumatoid arthritis affecting the wrist or to a Colles' fracture. In the remainder of cases, either a direct closed injury to the wrist or a hyperextension injury of the wrist is most often responsible. Far more unusual is a rotational injury which can cause complete avulsion of the EPL tendon at the musculotendinous junction. A delayed rupture is most probably caused by an avascular necrosis secondary to traumatic disruption of the mesotendon. Surgical correction of the injury is best accomplished by tendon transfer, using the extensor indicis proprius. Postoperative immobilization, hyperextension of the thumb, and adequate resting tension are all necessary to assure good return of function. Postoperatively, the patient may experience a slight decrease in extensor strength of the index finger which may or may not be accompanied by a minimal loss in extensor range.