ObjectiveTo explore the effectiveness of the side island flap coinciding dorsal branch of the digital nerve for repairing thumb pulp defects. MethodsBetween May 2008 and July 2012,36 cases of thumb pulp defects were treated with the side island flap coinciding dorsal branch of the digital nerve.There were 26 males and 10 females,aged 21-51 years (mean,32.4 years).The injury causes included electric saw injury in 14 cases,punch press injury in 8 cases,machine twist injury in 5 cases,door crushing injury in 5 cases,and glass cutting injury in 4 cases.The left hand was involved in 12 cases and the right hand in 24 cases.Combined injuries included tendon and bone exposure in all cases,fracture of the distal phalanx in 3 cases,and nail bed lacerations in 2 cases.The defect size ranged from 1.4 cm×1.2 cm to 2.5 cm×2.1 cm;and the flap size ranged from 1.8 cm×1.4 cm to 3.0 cm×2.5 cm. ResultsTwo flaps with distal skin flap tension blisters and skin scabbing,which were cured after dressing changes;the wound healed by first intension in the other 34 cases.The skin grafts at donor site survived,and primary healing of incision was obtained.The patients were followed up 3-15 months (mean,8 months).The appearance and function restored well.Two-point discrimination of the flap was 5.2 mm on average (range,4-8 mm) at last follow-up.The finger joint had no stiff.According to the upper extremity function evaluation criteria issued by the Hand Surgery Society of Chinese Medical Association,the sensation was S4 in 33 and S3+ in 3 cases.No ectopic feeling was observed.The extension and flexion activity of fingers at donor site was normal,the sensation reached S4 with no atrophy of the finger. ConclusionWith constant anatomy,reliable blood supply,and safe operation,the anastomoses of the finger side island flap with dorsal branch of digital nerve is a better method to repair thumb pulp defects because it also effectively overcome the ectopic feeling with traditional methods and protect feel function of the fingers at donor site.