Effects of tendon transfer to restore index finger abduction for severe cubital tunnel syndrome

BACKGROUND Severe cases of cubital tunnel syndrome do not always result in functional recovery after surgical decompression of the ulnar nerve. A combined operation of tendon transfer to restore index finger abduction and decompression of the ulnar nerve was performed for patients with severe cubital tunnel syndrome who required powerful pinch strength and whose preoperative compound muscle action potential of the abductor digiti minimi muscle was not recordable or almost non-recordable. The purpose of this study was to assess the efficacy of tendon transfer to restore index finger abduction for severe cubital tunnel syndrome. METHODS Sixteen hands in 15 patients with severe cubital tunnel syndrome were operated on with extensor pollicis brevis tendon transfer to the first dorsal interosseous muscle to restore index finger abduction and ulnar nerve decompression. They were reviewed after a mean follow-up of 16 months. All 16 hands had preoperatively severe lesions with paralysis of ulnar intrinsics, marked anaesthesia, or hypaesthesia. RESULTS Postoperative results were excellent in 2 hands, good in 10, fair in 4, and no cases with poor results according to Akahori's criteria. Four hands with fair results had a residual Froment sign or annoying hypaesthesia in the ring and little fingers. All patients were relieved of preoperative discomfort and showed recovery of motor and sensory function. The mean pre- and postoperative pinch strength was 3.3 kg and 5.6 kg, respectively, which showed a significant difference (P<0.01). Mean time of showing a negative Froment sign after surgery was 5 months in 13 cases. CONCLUSIONS The extensor pollicis brevis tendon transfer is simple and useful to restore index finger abduction and pinch strength for severe cubital tunnel syndrome.