Fig. 1

a The reverse dorsoradial flap of the thumb was designed on the radial dorsal area of the thumb according to the size of the skin defect on the dorsal side of the thumb. The rotation point is located on the radial side of the thumb interphalangeal joint. The axis aligned the radial side of the carpal joint with the radial side of the interphalangeal joint. The flap and pedicle included the superficial branch of radial nerve of dorsal thumb. b The middle finger proper digital arterial island flap was then designed according to the injury size of the palmar thumb. The flap contains dorsal branches of the proper digital nerve. The pedicle of the flap was designed as a narrow shape encompassing the proper palmar digital artery of the ulnar side of the middle finger. The radial proper digital artery of the ring finger was cut off and ligated at the beginning. c Under the microscope, the dorsal branch of the digital proper nerve was anastomosed with the ulnar proper nerve of the thumb. The reverse dorsoradial flap of the thumb and the middle finger proper digital arterial island flap were used to repair the degloving injury of the distal thumb