Objective To understand the clinical effect of peroneal nerve trophic vascular retrograde flap to repair tissue defects in the lower calf and foot. Methods From June 1997 to August 2007, the author used peroneal neurotrophic vascular retrograde island flap (46 cases) or myocutaneous flap ( 10 cases) for repair. The area of the flap was 5 cm×4 cm and 22 cm×16 cm, and the donor area was closed by direct pulling together or free implantation. In 55 patients, the flap was completely viable and the wound healed after surgery. There was no complication in 3-6 months of follow-up, and the flap had good texture and satisfactory appearance. The patients walked normally, but the recovery of the sensory function of the flap was not good. l patient did not remove part of the necrotic tibia in order to preserve the length of the lower limb during the treatment. One month after the operation, the skin broke down, and the wound healed after reoperation. Conclusion Peroneal nerve trophic vascular retrograde island flap or myocutaneous flap transplantation is a better method to repair soft tissue defects in the lower calf and foot. Lower calf and foot are difficult to repair once damaged due to little subcutaneous soft tissue and poor blood supply. Since the first case of superficial branch of radial nerve free flap transplantation with anastomotic vessels was reported in 1976, a large number of domestic and foreign studies on the blood supply of the human cutaneous nerve have been carried out in a systematic manner, and a class of flaps based on the blood supply of the cutaneous nerve has appeared, such as retrograde island flap with cutaneous nerve and its trophic vessels, and retrograde island flap with peroneal nerve and its trophic vessels, which is often used for repairing limb wounds. From June 1997 to August 2007, the author used peroneal nerve trophic vascular retrograde island flap or myocutaneous flap supplied by peroneal artery perforating branch to repair the soft tissue defect wounds in the lower calf and foot of 56 patients, and the therapeutic effect was satisfactory. 1, data and methods 1.1 Clinical data The patients in this group were 49 male and 7 female, aged 6-78 years old. All of them were transferred to the Burns Department of Jishuitan Hospital after early debridement and suturing in other medical units, or after internal fixation, or inan existence of deep trauma repair}l=l difficult and so on. Among the patients, 48 cases of trauma-induced soft tissue defects and 8 cases of electrical burns were reported. Among them, there were 10 cases of simple soft tissue defects in the lower part of the calf; 38 cases of traumatic infection, tibial and fibular fracture exposure, and osteonecrosis; 8 cases of tissue defects in the foot (including the heel), affixed bone scarring, and osteomyelitis. 1.2 For traumas with large skin defects, the infected and necrotic soft tissues were thoroughly excised during the operation. For wounds with small skin defects or sinus tracts, inject methylene blue solution into the sinus tracts 24-48 h before surgery, and thoroughly remove the blue-stained necrotic tissues during surgery; or remove the lesions according to the lesions suggested by sinus imaging, scrape off the dead bone and surrounding inflammatory tissues, chisel the sclerotic foci around the sinus tracts to the healthy bone tissues, and excise the scar around the sinus tracts. For the part of necrotic tibia that had been exposed or immersed in pus for a long time, the diseased tissue was completely removed according to the x-ray film prompting to reach the normal bone. The wound was flushed with isotonic saline, 3% hydrogen peroxide by volume, and povidone-iodine solution. The internal fixation of the infected wound was removed. Switch to unilateral external fixation bracket fixation. 1.3 The flap design was examined with ultrasound Doppler flow detector before surgery to determine the lowest part of the peroneal artery at the point where the posterior superior perforating branch of the external ankle emanated (3-5 cm above the external ankle), which was used as the rotation point. The line from the midpoint of the carcass fossa to the midpoint of the Achilles tendon and the outer ankle was used as the axis of the flap, and the flap could be extended to the midline of the medial and lateral calf on both sides of the flap, to the lower part of the carcass fossa on the upper side, and to the peroneal artery perforating branch on the lower side. According to the size and shape of the trauma, island flap or myocutaneous flap is designed to ¨lead. 1.4 The flap was cut by retrograde method. First, a transverse incision is made above the flap to reveal the small saphenous vein and the medial peroneal cutaneous nerve to determine its passage into the flap, and the position of the flap is adjusted according to the direction of the nerve and nutrient vessels. The nerve was severed above the flap, the blood vessels were ligated, and the skin around the flap was incised to reach the deep subfascia. The flap and the neurovascular tip were lifted retrogradely from the deep subfascia, and the tip contained only the saphenous vein, peroneal nerve, and trophic vessels in the fascial tissue. The flap is wide at the top and narrow at the bottom, with a rotation point of 2 cm, and the flap is supplied with blood from the peroneal artery. In the upper middle calf, the cutaneous nerve travels within the medial and lateral head of the gastrocnemius muscle or within the muscle, and the nerve and muscle (muscle cuff) should be brought into the flap when it is cut in order to improve blood flow. When cutting the musculocutaneous flap, attention should be paid to the gastrocnemius muscle and the neurovascular tip and flap can not be separated. According to the size of the flap, the amount of tissue in the tip and the skin between the point of rotation and the recipient area, it is determined that the flap is displaced by a bright channel or subcutaneous tunnel. Do not distort, compress, or pull the tips. In this group of patients, 46 cases of island flap and 1 case of myocutaneous flap were cut, and the area of the flap was 5 cm×4 cm and 22 cm×16 cm. 13 cases of the flap area were directly pulled together and sutured, and the remaining 43 cases of the flap area were free skin grafting. 1.5 Postoperative treatment after surgery. Rubber drainage strips or negative pressure suction tubes were placed under the flap, which could be removed 48 h after surgery if there was not much exudation. Apply low molecular dextran and prostaglandin (prostaglandin El, Kaiser, Beijing Ted Pharmaceuticals) for 3-5 d to improve the microcirculation of the flap. The temperature of the skin flap was maintained and could be irradiated with a 60 w baking lamp. Sensitive antibiotics were selected according to the results of drug sensitivity test for 5-7 d. 2. Results 2.1 Overall situation 2.1 The flaps of 55 patients were fully viable and the planar surfaces were healed after surgery. Follow-up 3-6 months without any complications, the appearance of the flap is satisfactory, the patient walks normally, but the graft local sensory recovery is poor. l patient was treated to retain the length of the lower limb, did not remove part of the necrotic tibia, the skin broke down 1 month after the operation, and the wound surface was healed after removing the dead bone by another operation. 2.2 Typical cases The patient was a male, 35 years old, with a chronic sinus tract formed in his right calf for 4 years after being smashed by a coal truck. On examination after admission, extensive scarring of the distal right calf was seen, and there were 2 soybean-sized chronic sinus openings about 2 cm above the outer ankle (Figure 1). Surgical excision of part of the scar tissue revealed a large amount of coal ash powder and inflammatory granulation on the anterolateral aspect of the Achilles tendon, which was removed to form a 4-cm × 2-cm-sized cavity at the entrance, the depth of which was almost up to the contralateral subcutis (Figure 2). A 15 cm × 7 cm peroneal neurotrophic vascular retrograde island flap was designed in the posterior aspect of the patient’s calf, and part of the gastrocnemius muscle was excised. The flap was transplanted into the trauma, the gastrocnemius muscle was filled in the surgical cavity, and the donor area was closed with a skin graft. The stitches were removed 2 weeks after surgery, and the flap and graft were well viable. The patient’s right foot and ankle were traumatized and formed a chronic sinus tract for 4 years.2 The patient’s right foot and ankle were cleared and planed. The patient’s right foot and ankle formed a deeper cavity with a population of 4 cm×2 cm.3 Discussing the soft tissue of the lower part of the lower leg and the foot is thin, and the subcutaneous tissue and fat are very little, trauma, infection, etc., are easy to cause tissue defects, deep tissue exposure and bone infection; on the other hand, since the blood supply of this part is mainly composed of the terminal branches of the anterior tibial artery, posterior tibial artery and peroneal artery and their traffic branches and anastomotic network, it is very easy to cause insufficient blood supply or bone It is very easy to cause insufficient blood supply or bone nonunion and osteonecrosis, and how to repair and reconstruct it is a clinical problem. In the past, for exposed bone, the treatment method of bone drilling, waiting for the growth of granulation tissue and then skin grafting was often used, which was time-consuming and prone to ischemic necrosis due to prolonged bone exposure and secondary infections; and the indications for the surgery were limited by the complexity and limitations of the cross leg flap and the free tissue flap. As the anatomical study of local blood supply arteries and their anastomotic network structure continues to deepen, the distal calf tip tissue flap transplantation without damaging the main artery has little damage to the donor area, good coverage of the recipient area, simple operation, and easy to survive, and in recent years it has been widely used in the clinic, becoming the first choice for repairing tissue defects in the lower part of the lower calf and the foot. The peroneal artery perforating branch-supplied peroneal nerve trophic vascular retrograde island flap or myocutaneous flap is one of them. In this group of patients, the primary injury was severe, mostly accompanied by comminuted fracture, in addition, they were all transferred from other medical units, and there were cases of early mismanagement, such as: tibial and fibular fracture after calf swelling is obvious, obvious, but did not carry out the incision to reduce the tension. This resulted in osteofascial compartment syndrome, leading to necrosis of nerves and muscle tissues; skin exfoliation injuries after only a simple debridement suture, did not carry out reverse skin grafting. This causes skin necrosis in the exfoliation area; open or even closed fracture postoperative infection, etc., which ultimately leads to large soft tissue defects in the calf and foot, tendons, ligaments, osteoarthritis, and large exposed fracture segments, and comminuted fractures are also more often developed into infected dead bones. Intraoperatively, it is common that a large number of muscles in the calf area are necrotic or interstitial, and even months after the injury, edema is still obvious, and it is not possible to perform local muscle flap transfer to repair the wound; and extensive soft tissue loss in the foot leads to the impossibility of local repair, and peroneal artery perforating branch of the peroneal nerve trophic vascular retrograde island flap has become one of the preferred methods of repair. Necrotic tissue is a source of infection that is difficult to control. Thorough debridement is an important guarantee of surgical success. The extent of necrotic tissue in this group of patients can be determined with the help of x-rays, injection of methylene blue into the sinus opening, sinusography and other methods according to the size of their traumatic defects and the presence or absence of sinus tracts. The internal fixation of infected wounds is easily loosened and often surrounded by inflammatory tissue, which can lead to long-term infection of the wound, and should be changed to a unilateral external fixation frame.