Spontaneous Zone III Flexor Tendon Rupture of the Little Finger: A Case Report

Abstract

Closed flexor tendon ruptures are uncommon, and most are avulsion ruptures from the tendon insertion. Such intratendinous ruptures are generally associated with an underlying pathological process such as inflammatory disease; purely spontaneous ruptures are very rare. A 66-year-old male patient presented with sudden loss of flexion in the left little finger distal interphalangeal joint (DIPJ) while rotating a steering wheel. Preoperative ultrasonography and magnetic resonance imaging (MRI) suggested a closed flexor digitorum profundus (FDP) injury in the substance of the tendon. Surgical exploration revealed a zone III rupture in the FDP tendon. After tenorrhaphy, early postoperative exercise using a dynamic splint was initiated. At 8 months’ follow-up, he had regained flexion of the DIPJ and was free of pain. We recommend that patients with suspected closed flexor tendon injuries promptly undergo preoperative imaging studies such as ultrasonography or MRI to determine the rupture site, facilitating preoperative planning and reducing surgical morbidity.