Clinical application of lateral femoral perforator flap With the gradual promotion of perforator flap in clinical practice, the anterolateral femoral perforator flap supplied by the spinolateral femoral artery system reported by koshima [1-3] is familiar to the majority of clinical workers, and the human lateral femoral region is rich in perforators, which can be used as an ideal flap donor area but is less valued by clinical workers. from January 2009 to October 2011, we used From January 2009 to October 2011, we used lateral femoral flaps to repair soft tissue defects in the extremities, and achieved good results, which are reported below. 1, clinical data The group of 13 cases, male, age 19 to 70 years old, average 35.3 years old. The flap area was from 3cm×3cm to 19cm×8cm, 1 case with tip inversion, 12 cases of free graft, including 2 cases of lobulated flap and 2 cases of combined graft with anterolateral femoral flap. 10 cases of direct vascular anastomosis and 2 cases of tandem vascular anastomosis. The donor area was directly sutured in 11 cases and partially closed with skin graft in 2 cases. 2.Surgical method Preoperatively, the lateral femoral condyle and the greater trochanter were positioned by Doppler penetration, and the flap was designed with the penetration point as the center. The patient was placed in a supine position, with the hip and knee flexed and the buttocks padded underneath, and the assistant fixed the heel and supported the knee so that the thigh was internally rotated and assisted in the lateral dissection. The flap is first incised anteriorly to the lax tissue on the superficial surface of the broad fascia (or iliotibial bundle) and dissected from anterior to posterior to the lateral femoral septum. In the upper and middle thighs, the broad fascia on the surface of the septum is tightly attached and needs to be sharply dissected, while the middle and lower septum is looser and can be bluntly dissected. After separation, one or several penetrating branches can be clearly seen from the lateral septum into the flap. Sometimes two or more dermal branches (Y-shaped branches) can be encountered from a single penetrating branch, which should be dissected along its course to the point of fusion with the main penetrating branch. After entering the septum, the lateral femoral muscle is drawn forward and the vessels are dissected toward the femur, where a thick vessel (depending on the individual, it may be the 3rd or 4th penetrating artery of the deep femoral artery or the superior external knee artery) can be seen penetrating below the thick line of the femur, giving rise vertically outward to the biceps femoris musculocutaneous penetrating branch, an upward lateral femoral muscle branch, and a trunk that continues distally along the femur. The lateral femoral branch is ligated to protect the biceps femoris musculocutaneous penetration branch before separating proximally. The biceps femoris is loosened from its attachment on the thick line into the posterior thigh space, at which point a sufficient length of vascular tip can be freed. A certain length of the distal arterial trunk can be reserved for flow through after the myocutaneous penetration of the penetrating artery. After complete separation of the vascular tip, the posterior aspect of the flap is incised, again in the superficial fascial layer, to the lateral femoral septum, and finally to the penetrating branch into the flap. At this point, only the flap remains connected to the vascular tip, and after adequate hemostasis, the blood circulation of the flap is examined and the tip is broken. If a lateral femoral sensory flap is made, the lateral femoral cutaneous nerve should be included when the flap is cut. The subcutaneous fat beneath the flap can be cut together to protect the nerve branches, and the trunk can be left as a nerve anastomosis. 3. Results In this group of 13 flaps, all of them were successfully revived. 1 case of partial necrosis of the donor skin implant and 2 cases of direct suture of the donor area showed small necrosis of the wound skin due to greater skin tension, which healed after drug exchange. The flap was not bloated, soft and elastic, with good color, hardy and not afraid of cold, and no frostbite or ulceration occurred, and the sensation of the flap was restored to s2, and that of the anastomotic nerve was restored to s3 in one case. none of the cases had muscle adhesions or scar contracture deformity in the donor area, and only linear scars were left in the cases with direct pulling together of the donor area and sutures, and the implant area was full and without The implant area is full without depression. 4. Typical case The patient, male, 45 years old, was admitted to the hospital as an emergency with a 4-hour trauma to the left foot. The examination revealed a 14×11 cm trauma to the medial ankle, a defect of the medial ankle and medial collateral ligament, an open and exposed ankle joint (Figure 1), a defect of the joint capsule, and a fracture of the lateral ankle bone. The trauma was cleared, the external ankle fracture was fixed with hollow screws, and the right thigh broad fascia was cut to repair the joint and medial collateral ligament. A 15-cm×12-cm flap was designed with the left fibular tuberosity-femoral greater trochanter line as the axis and 13.8±1.5 cm on the fibular tuberosity as the center point (Figure 2). The flap was free and the wound was repaired (Figure 3). The donor area was partially repaired with a skin graft. The wound healed and stitches were removed 15 days after surgery. 6 months follow-up, the flap was in good shape (Figure 4), the donor area was not bloated, and the knee function was not affected (Figure 5). 5, Discussion 5, 1 Advantages of the lateral femoral perforator flap 1) This flap is a development based on the myofascial flap with little damage to the donor area and good repair of the recipient area. 1983 Baek [4] first reported the clinical application of the lateral femoral perforator flap. Subsequently, Maruyama Y , Angrigiani C [5-6] reported the tipped transfer of the lateral femoral fasciocutaneous flap.Miller, Hayden RE, Baek CH [7-9] applied the free lateral femoral (muscle) fasciocutaneous flap in oral and maxillofacial surgery. Their isolated lateral femoral flaps (lateral thigh flaps) are myofascial flaps because they contain broad fascia in the isolated flap and sometimes have a muscle sleeve to protect the vascular tip. Because the broad fascia and part of the biceps femoris are removed, the donor area is more damaged, and the flap is obviously bloated. In our group, the Baek method has been improved by removing the flap without the deep fascia, containing only the skin, subcutaneous fat and the perforator tip. Most of the free flap grafts in clinical practice are intended for surface skin soft tissue coverage, and only a few are intended to fill in dead spaces or deep defects. Therefore, the lateral femoral perforator flap is more in line with the reconstruction principle of “fill what is missing” [10]. In a study by Tang Juyu [11], the donor area located in the lateral lower thigh (9.21±2.31) mm was the thinnest of all flap donor areas. Thus, this donor area has a better flap repair profile and does not require re-surgical reshaping at a later stage. In contrast to the anterolateral femoral penetration flap, the descending branch of the lateral spinous femoral artery is accompanied by the lateral femoral muscle branch of the femoral nerve, and the vascular nerves are interspersed, often forcing the nerve branch to be cut in order to dissect the vessels, and the lateral femoral muscle to be cut when dissecting the musculocutaneous penetration, all of which can result in reduced knee extension strength. In this group, the separation of the flap is performed in the septum, without the neuromuscular branch, without cutting the broad fascia, preserving the integrity of the broad fascia, without causing quadriceps adhesions, without carrying the muscle, and with less functional impairment of the knee joint. 2) The “T” shaped vascular tip of the flap has some clinical value. After the deep femoral artery penetrates the artery vertically to the lateral side, the main trunk continues to travel distally, and the distal section of the vascular tip is dissected out to form a “T” shaped vascular tip. This anatomical feature allows the lateral femoral perforator flap to be tandemly anastomosed with the anterior external femoral perforator flap or other flaps to form a combined graft flap to repair particularly large and irregularly shaped wounds. When the flap width is too large, the donor area cannot be directly sutured if it is designed to be cut in one block, and direct skin grafting on the broad fascia is not easy to survive; if the broad fascia is removed, skin grafting on the quadriceps or biceps will result in muscle-skin adhesions, which will affect muscle gliding and cause discomfort to the patient, and large defects of the broad fascia will also cause reduced knee extension strength. In this group of 2 cases, a large wound was separated into two flaps for repair, so that the width of both flaps did not exceed 9 cm (the optimal width was 5-7 cm), and the donor wound could be directly sutured by reducing the width and increasing the length of the donor area in the same area. This reduces the number of skin grafts, preserves the integrity of the broad fascia, and reduces functional impairment of the donor area. When the donor area requires both soft tissue coverage and long segmental vascular bridging, the “flow through” procedure not only reconstructs the surface soft tissue coverage but also reconstructs the distal blood flow of the limb, and the “T” shaped vascular tip is particularly valuable. 3) Lateral femoral The lateral femoral flap can be a useful complement to the anterolateral femoral flap. Currently, the most clinically used anterolateral femoral perforator flap is the anterolateral femoral perforator flap [12]. About 20% of clinically rotated lateral femoral artery descending branches have vascular variants, no intermuscular skin branches or musculocutaneous perforators, or the perforators are small and variants. Luo Lixiang [13] et al. reported 2.7% of descending branches without myocutaneous perforations. In some patients with small perforations, it is difficult to identify them during surgery, which may lead to surgical failure, especially for less experienced surgeons. Following the principle of “pressure balance”, if the anterolateral femoral perforator is small, the lateral femoral perforator is usually compensatory thicker, and the two flaps are adjacent to each other, so there is a certain commonality when cutting, which can be used as a remedial measure. 4) The flap can carry the dermal nerve and reconstruct the sensation of the recipient area. It is advantageous in repairing the sensation of the affected area compared with the inferior abdominal wall artery penetrating flap (DIEP) and the thoracodorsal artery penetrating flap (TAP) [14].5) The flap can also be made into lobed and multi-lobed flaps. In our group, we found that the same penetrating artery can sometimes find multiple skin penetrating branches, while the 3rd and 4th penetrating arteries co-truncate with the deep femoral artery and communicate with the lateral superior knee artery, so these features were used to create two cases of one-tip, two-lobe flaps to repair two unconnected wounds of the fingers (toes) successfully. 5.2 Disadvantages of the lateral femoral perforator flap 1) The flap has a limited maximum excision width. Because the circumference of the lower lateral femoral segment is smaller than that of the middle and upper segments, although successful cases of 16×30 cm flaps have been reported, the lateral femoral donor area is relatively small compared with the 22×32 cm excisional area of the anterior femur, especially when the flap width exceeds 9 cm, the donor area is difficult to suture, and the skin implants on the broad fascia are not easily survivable. Therefore, when the flap area is particularly large, consider the combination of perforator flap grafting, and for small and medium areas, when the flap is cut within 5-7 cm in width, the lateral femoral perforator flap is more valuable. 2) The location of the perforator shallow exit point still has variation, a common defect of all perforator flaps. Preoperative localization using Doppler ultrasound helps to locate the vascular penetrating branch during surgery. 3) There are difficulties in identifying the source of the penetrating artery during surgery. It is customary to identify the penetrating artery of the deep femoral artery by identifying the inferior border of the pubococcygeus muscle as the 1st penetrating artery, the inferior border of the short retractor muscle as the 2nd penetrating artery, the inferior border of the greater retractor muscle as the 3rd penetrating artery, and the terminal branch of the deep femoral artery as the 4th penetrating artery. Because it is generally not possible to reveal the full length of the deep femoral artery intraoperatively, it is also not possible to reveal all of the greater trochanter and short trochanter within the limited operative field. In addition, individuals with vascular variants may have more than one penetrating artery at the inferior border of the greater trochanter. Therefore, it is often not possible to determine the specific perforator of the flap from which artery it originates. 5.3 Naming of the lateral femoral perforator flap There has been no fixed pattern for naming the perforator flap, and there are several ways to name the flap, which are to prefix the name of the perforator flap with a modifying limiting term, such as donor site, trunk vessel, deep muscle, etc., i.e., “anatomic site + perforator flap”, “deep trunk vessel + perforator flap”, and “deep trunk vessel + perforator flap”. deep trunk vessels + perforator flap,” “deep muscle + perforator flap,” and so on. In 2003, Geddes [15] proposed a more accurate nomenclature for all flaps based on the source artery, i.e., the initials of the blood supplying artery of the flap, followed by P (perforator) to indicate the perforator, followed by the name of the source muscle. According to Geddes’ naming system for myocutaneous vascular perforator flaps, both the source artery and muscle should be specified. The source vessel of the present flap was mainly the 3rd perforator artery of the deep femoral artery, and the myocutaneous branch of the 3rd perforator artery penetrated the biceps femoris and lateral femoral muscle gap to form a dermal branch to re-nourish the flap. Accordingly, the flap should be named “deep femoral artery 3rd perforating artery biceps femoris perforator flap”, but the lateral middle and lower femoral perforators are multi-source, and there are 2nd and 4th perforating arteries, N artery skin branch and superior lateral knee artery in addition to the 3rd perforating artery of deep femoral artery, and more importantly, the operator could not determine the specific source artery of the perforator during the operation, so this name is obviously inaccurate. This name is obviously inaccurate. If we follow the nomenclature of “deep muscle + perforator flap”, this group of flaps should be called “biceps femoris perforator flap”. However, this name is not comprehensive for some flaps that do not penetrate the biceps femoris muscle but are formed by the direct branch of the first penetrating artery, and the nomenclature is not accurate enough to describe only the flaps located in the lateral region of the lower and middle thighs, because the skin covered by the penetrating branch of the biceps femoris muscle is so extensive. The authors tentatively adopted the nomenclature of “anatomic site + perforator flap” and tentatively referred to this group of flaps as “lateral femoral perforator flap”, which is defined as a flap located in the lateral region of the lower and middle thighs, supplied with blood and nutrients by the perforator, including only the skin and superficial fascial layer of subcutaneous tissue and vascular tips. The lateral femoral perforator flap has a reliable blood supply, a thin and soft flap, and the perforators are mostly septal perforators, which are relatively simple in anatomy and can carry sensory nerves to reconstruct the sensation of the flap.