Three rare causes of extensor tendon rupture.

Three unusual cases of rupture of finger extensor tendons by attrition are reported. In one instance it was associated with long-standing nonunion of a scaphoid fracture, with a posttraumatic dorsal subluxation of the lower end of the ulna in another, and with a Madelung's deformity in the third. Extensor tendon rupture has not been previously recorded in the English-language literature after the first two conditions.