Spontaneous Zone III rupture of the flexor tendons of the ulnar three digits in elderly Korean farmers.

Spontaneous flexor tendon rupture is a rare condition and the aetiology is not clear. We report 12 elderly Korean farmers with spontaneous flexor tendon ruptures. We found the rupture in the dominant hand in ten patients. A rupture in the little finger was found in all 12 patients (seven with both flexor tendons ruptured and five with only the profundus ruptured), in the ring finger in four patients (the profundus ruptured in all and both flexor tendons in two patients), and in the middle finger a partial rupture of the profundus in one patient. The tendons were ruptured close to the hook of the hamate. Repetitive friction between the flexor tendons and the hamate hook may cause the ruptures. The hamate hook was excised and the ruptured profundus tendons were reconstructed with tendon transfers with quite favourable functional recovery at follow-up of 1 to 2 years. The ruptured superficialis tendons were not reconstructed. Level of Evidence IV.