The invention relates to medicine, in particular to traumatology and plastic surgery and can be used for vascularized flap grafting of the patellar tendon septic defect.Summary of the invention consists in that it is performed the dopplerographic examination to identify the projections of perforated vessels of the posterior tibial artery, is detected the projection of the closest to the defect perforated artery, are determined the sizes of the expected flap depending on the size of the defect, is performed a longitudinal ellipsoidal incision with the convex side up to 1 cm from the selected perforated vessel, is continued the incision in the distal direction with the formation of a flap, which includes the skin, the covering fascia and a 1x5 cm fragment of gastrocnemius muscle tendon, the formed flap is applied on the selected perforated vessel without traumatizing from the anterior side the subcutaneous neurovascular fascicle, after which the flap is rotated by 170°…180°, so that the tendon fragment included in the flap may cover the defect between the ends of the patellar tendon and are sutured to the ends of the tendon fragment the ends of the patellar tendon, and then the wound is sutured in layers.