[Closed injuries of the extensor hood of the metacarpophalangeal joint].

Closed traumatic lesions of the extensor tendon hood of a longfinger at the metacarpophalangeal joint are rare. Surgical treatment was done in 6 cases during the last 10 years in our department; in 5 cases the dorsoradial part, in one case the dorsoulnar part of the hood was injured. The tear extended longitudinal or diagonal through the transverse fibers of the hood. Respecting the accident mechanism there have been reported tangential forces at the extensor tendon hood and forced ulnar deviation in the bended metacarpophalangeal joint. A jerky dislocation of the extensor tendon to the ulnar side of the metacarpophalangeal head during increased bending of the metacarpophalangeal joint, sometimes with ulnar abduction of the longfinger, leads usually to the diagnosis. Misdiagnoses of cases sent to our department were: "trigger finger" and "recurrent dislocation of the metacarpophalangeal joint". Once the presurgical diagnosis was "rupture of the extensor tendon" because of a permanent extension deficit in 30 degree position of the metacarpophalangeal joint. Treatment is always surgical with suture of the hood and immobilization of the metacarpophalangeal joint in extension position for 4 weeks. Conservative treatment can not heal up a tear of the extensor tendon hood.