Biomechanical explanation of a simultaneous closed rupture of both flexor tendons in the same digit.

Closed ruptures of both normal flexor tendons in the same finger are extremely rare, only nine cases having been reported in the literature. The authors describe the case of a patient who sustained a closed rupture of both flexor digitorum profundus and flexor digitorum superficialis of the ring finger, following a forced hyperextension injury. The present paper highlights the importance of the mechanism of injury and explains biomechanical basis. The patient was treated by a two-stage reconstruction of the flexor digitorum profundus and regained full flexion and extension of the finger.