ObjectiveTo study the effectiveness of anterior subcutaneous transposition of ulnar nerve with reconstruction of hand intrinsic muscle in the treatment of severe cubital tunnel syndrome. MethodsBetween March 2006 and May 2015, 22 cases (23 hands) of severe cubital tunnel syndrome were treated by use of anterior subcutaneous transposition of ulnar nerve with reconstruction of hand intrinsic muscle. There were 15 males and 7 females, aged 45-60 years (mean, 55 years). The causes were valgus deformity of elbow joint in 12 cases, ulnar nerve subluxation in 4 cases, and osteoarthritis in 6 cases. The disease duration was 10 months to 3 years (mean, 17 months). According to Akahori classification, 14 cases were rated as type 4 and 9 cases as type 5. The ring/little finger's numbness, hand intrinsic muscle atrophy, recovery of thumb adduction function, and improvement of claw hand deformity were observed after operation. Thumb and index finger's pinch strength was measured by use of pinch device; postoperative hand function was evaluated by the standards of Chinese Medical Society of Hand Surgery of upper limb assessment protocol. ResultsAll incisions healed well and all cases were successfully followed up 8 to 24 months (mean, 14 months). Numbness of ring/little finger was significantly reduced at 1 day after operation in 10 hands; numbness disappeared completely at 1 month after operation in 12 hands; mild numbness remained at 14 months after operation in 11 hands. At last follow-up, hand intrinsic muscle atrophy partially improved (+++) in 1 hand, no improvement in 22 hands; improvement of claw hand deformity was achieved in 17 hands, no improvement in 6 hands; pinch strength of thumb and index finger was significantly improved to (5.07±1.11) kg from preoperative (2.91±0.63) kg (t=-12.340, P=0.032). At last follow-up, the results were excellent in 11 hands, good in 8 hands, fair in 3 hands, and poor in 1 hand, and the excellent and good rate was 82.6%. ConclusionAnterior subcutaneous transposition of ulnar nerve with reconstruction of hand intrinsic muscle is a simple, effective, and reliable surgical treatment for severe cubital tunnel syndrome.