Rupture of the flexor digitorum profundus tendon to the small finger within the carpal tunnel.

We report three patients who sustained a rupture of the flexor digitorum profundus tendon to the small finger within the carpal tunnel. There was a common mechanism of injury, each rupture occurred during resisted flexion of the digit with the metacarpophalangeal joint in extension. All the patients were male, one patient had an asymptomatic undiagnosed fracture of the hook of hamate, one patient had radiological evidence of piso-triquetral osteoarthritis. In each case, an attrition rupture was confirmed at surgery.