Closed Rupture of the Flexor Profundus Tendon of Ring Finger: Case Report and Treatment Recommendations.

Zone III midsubstance flexor tendon rupture without underlying pathology is rare. The most common mechanism of injury for a spontaneous rupture is forced extension of an actively flexed distal interphalangeal joint. We describe a patient who experienced closed midsubstance zone III rupture of the flexor digitorum profundus (FDP) tendon of the ring finger at the lumbrical origin in the palm while lifting a heavy object. On exploration, there was no evidence of underlying tendon pathology, and primary end-to-end repair of the FDP was possible. This case highlights the importance of correct preoperative clinical localization of the rupture level, as well as a suggested surgical plan in equivocal cases.