ObjectiveTo explore a new improved technique and its effectiveness to repair dorsal thumb composite tissue defects including interphalangeal joint by transplantation of modified hallux toe-nail composite tissue flap. MethodsThe hallux toe-nail composite tissue flap carrying distal half hallux proximal phalanx, extensor hallucis longus, and interphalangeal joint capsule were designed and applied to repair the dorsal skin, nails, and interphalangeal joint defect of thumb in 14 cases between January 2007 and June 2013. They were all males, aged from 19 to 52 years (mean, 30 years). The time from injury to hospital was 0.5-2.0 hours (mean, 1.2 hours). The area of the thumb nail and dorsal skin defects ranged from 2.5 cm×1.5 cm to 5.0 cm×2.5 cm. The dorsal interphalangeal joint had different degrees of bone defect, with residual bone and joint capsule at the palm side. The length of bone defect ranged from 2.5 to 4.0 cm (mean, 3.4 cm). The hallux nail flap size ranged from 3.0 cm×2.0 cm to 6.0 cm×3.0 cm. The donor sites were repaired by skin grafting in 5 cases, and retrograde second dorsal metatarsal artery island flap in 9 cases. ResultsAfter operation, arterial crisis occurred in 1 case and the flap survived after relieving pressure; the other flaps survived, and wounds healed by first intention. Liquefaction necrosis of the skin grafting at donor site occurred in 3 cases, and the other skin grafting and all retrograde second dorsal metatarsal artery island flaps survived. The follow-up ranged from 9 months to 3 years and 6 months (mean, 23 months). The secondary plastic operation was performed in 4 cases at 6 months after operation because of slightly bulky composite tissue flaps. The other composite tissue flaps had good appearance, color, and texture. The growth of the nail was good in 12 cases, and slightly thickened in 2 cases. At last follow-up, X-ray examination showed that bone graft and proximal phalanx of the thumb had good bone healing in 12 cases. Good bone healing was obtained at the donor site. According to the Hand Surgical Branch of Chinese Medical Association standard for thumb and finger reconstruction function, the results were excellent in 12 cases and good in 2 cases, and the excellent and good rate was 100%. No pain at donor site was observed, with normal gait. ConclusionTransplantation of modified hallux toe-nail composite tissue flap to repair dorsal thumb composite tissue defects including interphalangeal joint can effectively improve the appearance and function of the impaired thumb.