Hypothenar flap based on a cutaneous perforator branch of the ulnar artery: an anatomic study.

This study describes a constant cutaneous perforator branch of the ulnar artery of the hand and a hypothenar arterial flap based on it. Eighteen amputated hands of 10 fresh cadavers were used for the study. Red latex was injected into the axillary arteries of nine specimens and radiopaque lead oxide-gelatin mixture into the remaining nine. Then, the cutaneous perforator branch of the ulnar artery was identified by marginal dissection and radiographed. The cutaneous perforator branch was found constantly in all 18 specimens and was named the "hypothenar perforator" (HP). On radiograph, a coordinate was set up with an origin (pisiform), a transverse x (through the pisiform and hamate of the carpal bones), and a proximal to distal y (through the pisiform and 4th interdigital web) axes. The HP was situated at 10.1 +/- 3.6 mm lateral to the pisiform (on the x axis) and 20.0 +/- 7.0 mm distal (on the y axis). A hypothenar flap based on the HP is suitable for covering small defects of the fingers, and the donor site can be closed primarily.