Lateral Thigh and Anterolateral Thigh Free Tissue Transfer Treatment & Management

Monitor and anesthetize the patient as indicated for a long procedure. For the lateral thigh flap, when the patient is positioned, secure the foot and leg in a padded stirrup, shown below. The knee is flexed and the leg rotated externally to expose the posterolateral aspect of the thigh. No tourniquet is used. The entire thigh is prepped and draped.

The leg is placed in a padded support. The knee is rotated inwardly to expose the posterolateral aspect of the thigh, including the intermuscular septum.

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Anterolateral thigh flap

No special positioning is necessary for the anterolateral thigh flap. Angiographic and Doppler identification of perforating vessels may be helpful but is not critical to the success of the flap. ^[11] Multidetector row computed tomography has been found to indicate a sizable perforator with the shortest intramuscular course, which would lead to a shorter and safer operation. ^[12]

Lateral thigh free flap

Palpate the vastus lateralis and biceps femoris muscles. The intermuscular septum between these muscles is where the perforating vessels are found. The fasciocutaneous flap is designed in an off-centered fusiform shape around the midpoint of the thigh. The vessel used for anastomosis is most commonly found within 2.5 cm of the midpoint of the thigh; thus, the midpoint is a useful landmark. Measuring the distance between the greater trochanter and the lateral femoral condyle and dividing this distance by 2 determines the midpoint.

• Fasciocutaneous flap

  • Although the size of the flap is dictated by the needs of the head and neck defect, certain principles apply. Extend the superior margin of the flap to the border of the gluteus maximus to include the second perforator. Typically, a donor defect 8-10 cm wide is the maximum that can be closed without significant tension. Larger donor defects probably require a skin graft for closure.

  • Since the flap is thinner anteriorly, and the septocutaneous perforators predominately pass anteriorly over the iliotibial tract, most of the flap should lie over the iliotibial tract. This position accounts for the off-centered design of the flap. Two thirds of the flap width is designed to lie anterior to the intermuscular septum, with the remaining third lying posteriorly. A skin incision is made anteriorly, and the subcutaneous tissue is dissected from the iliotibial fascia itself as the skin and fat are retracted posteriorly. Bleeding is minimal in this plane.

  • The perforating vessels are identified and preserved in the flap fascia as the dissection is carried down to the intermuscular septum, as shown below. Care is taken to adhere to the iliotibial tract as the dissection proceeds in order to avoid damage to the vessels. The intermuscular septum is easy to enter inferiorly, but a bridge of fascia lata forms a roof over the septum superiorly. This bridge must be transected. At this point, the septum opens up widely. The long head of the biceps femoris falls posteriorly as the vastus is retracted anteriorly. Retraction of the vastus lateralis is best accomplished with 1 or 2 multiprong rakes that are suspended from a covered surgical stand, obviating the need for an additional assistant to retract. The rake or rakes are repositioned medially as the dissection proceeds proximally. See the image below.

    Initial dissection involves suspension of a rake from a surgical stand to grasp the tough fascia overlying the vastus lateralis. As dissection proceeds medially, the short head of the biceps femoris falls inferiorly. The hemostat indicates the third perforating vessels.

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  • To visualize the second perforator, separating the gluteus maximus from the iliotibial tract may be necessary. The third perforator is traced as it passes superiorly through, or posterior to, the short head of the biceps femoris. The fourth perforator is usually continuous with the third perforator via the PFA or a communicating branch. The adductor magnus and the short head of the biceps femoris must be detached extensively from the femur at the linea aspera so that the PFA and branching vasculature may be revealed, as shown below. See the image below.

    Schematic view of the completed dissection shows that the posterior skin incision has yet to be made. Harvest of the vessels usually is made where the PFA joins with the second perforator (not shown).

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  • At the point where the third perforator pierces the adductor magnus, some difficulty may be encountered. At this point, a number of vessels branching from the main pedicle are often encountered passing anteriorly into the iliotibial tract and posteriorly into the adductor magnus and short head of the biceps femoris. These branches may be confused with the main pedicle; therefore, ligate and transect them so that the more proximal portion of the pedicle can be observed. In the distal pedicle, 2 venae comitantes usually surround the artery, but they often combine proximally into 1 vein just prior to entering the PFV. Since the artery and veins have a convoluted relationship at this point, a wiser approach is to complete the vessel separation with the microscope after pedicle division. This difficult separation is unnecessary if the PFA and PFV can be dissected sufficiently proximal to this confluence of vessels.

  • When the profunda vessels are dissected proximally and circumferentially, the vessels are transected just distal to the second perforator. Since the PFA is used in continuity with the third and fourth perforators, pedicle length and vessel diameter are improved. Occasionally, the flap must be based on the fourth or second perforators instead of the third. Usually, the fourth perforator is too small to use alone. After finishing the dissection, the vessels may be left intact, and the flap may be stapled back into place until it is needed.

  • After the vessels have been isolated, the posterior skin incision is made. Preserving the posterior skin attachment supports the flap, prevents excess traction on the vessels, and also preserves a secondary blood supply to the skin if the vessels are inadvertently transected too early. When the recipient bed is prepared, the vessels are clamped, transected, and suture ligated. The flap is then prepared for anastomosis and inset.

• Fascial flap: The free lateral thigh fascial flap is elevated in much the same way as the fasciocutaneous flap. Since a skin paddle does not need to be designed, the flap is raised through a 16- to 24-cm incision lying over the intermuscular septum and centered over the midportion of the thigh. Anteriorly and posteriorly, fat is peeled from the undersurface of the skin, taking care to leave a 5-mm layer of adipose adherent to the dermis. Exposing bare dermis may cause necrosis of the overlying skin. The fat is then dissected from the vastus lateralis fascia, and the muscle is retracted as described above. The vessels are identified and traced in the usual fashion. The flap is harvested, and the incision is closed over a large suction drain.

• Sensate flap: The nerve supply to the flap is derived from the lateral femoral cutaneous nerve. This nerve divides into anterior and posterior branches. The posterior branch enters the flap from its superior and anterior aspects in the subdermal fat. Since locating the nerve is difficult, the recommendation is to make a separate longitudinal incision over the sartorius muscle in the anteromedial thigh. All the intervening subcutaneous fat is harvested along with the nerve to the flap.

Anterolateral thigh free flap

See the list below:

• Fasciocutaneous flap

  • A line is drawn from the anterior superior iliac spine to the superolateral border of the patella to approximate the anatomic position of the intermuscular septum between the rectus femoris and the vastus lateralis muscles. The perforating vessels of the flap can be identified with aid of Doppler probe within a 3-cm radius circle located at the midpoint of this line. The flap may be designed in such a way so as to be centered over the LCFA using a Doppler device.

  • The first incision is made medially, about 10 cm long and in a vertical direction over the rectus femoris muscle. The incision is deepened down through the subcutaneous fat and fascia. The fascia is dissected off the rectus femoris, and the thigh skin is raised and retracted laterally by subfascial dissection. At this point in the operation, one may visualize the LCFA in the intermuscular septum by retracting the rectus femoris muscle medially.

  • As discussed above, depending on the anatomy, either the transverse or descending branch of the lateral circumflex femoral is harvested. The surgeon should make two determinations at this point—whether to harvest the descending or transverse branch of the LCFA and whether septocutaneous or musculocutaneous perforators are present. If a large septocutaneous perforator is seen, the vastus lateralis muscle may be left alone. This perforator traverses the intermuscular septum between the rectus femoris and vastus lateralis muscles proximally. If more than one perforator is present, the most proximal one is the preferable choice for harvest because it has a relatively larger diameter.

  • More commonly, one will encounter musculocutaneous rather than septocutaneous perforators. The easiest way to preserve these vessels in the dissection is to include a cuff of vastus lateralis muscle with the main pedicle. This maneuver obviates the need to skeletonize specific perforators.

  • In roughly 2% of cases, no perforator is present. ^[13] One must then decide to either explore anteromedial thigh territory to look for perforators through the rectus femoris or sartorius muscles or to use the other leg.

  • After the main pedicle has been visualized through the medial incision, an incision is made laterally through the skin and fascia lata. The location of the lateral incision, of course, will depend on how wide the skin paddle needs to be for reconstructive purposes. Undermining is carried deep to the fascia lata laterally onto the vastus lateralis muscle. The musculocutaneous perforators are then elevated along with a 0.5- to 2.0-cm cuff of vastus lateralis muscle attached to the pedicle. Careful division and ligation of several muscular branches are important at this point. These vessels will frequently go into spasm, and the muscle may bleed excessively after revascularization.

  • After carefully dividing and ligating the remaining muscular branches to the rectus femoris and vastus lateralis muscles, the descending branch or transverse branch of the lateral circumflex femoral artery is then isolated. The motor branches of the femoral nerve that innervate the vastus lateralis muscle generally accompany the descending branch of the LCFA. It is no longer clear that these branches must be carefully preserved. In a large series of anterolateral free flaps, the nerve was transected in 22% of cases, and no postoperative sequelae were noted. ^[14] Depending on how large the flap is, the defect may be either closed primarily or skin grafted. Flap elevation generally takes about 60-90 minutes.

• Fascial flap

  • In those situations requiring only soft tissue bulk and no epithelial lining, an anterolateral free fascial flap may be raised. This includes the vasculature, the subcutaneous fat, the fascia lata, and a portion of the aponeuroses of the rectus femoris and vastus lateralis muscles. This flap is raised via the medial skin incision only.

  • After the vessels are visualized and dissected out, the subcutaneous fat is peeled off the undersurface of the lateral thigh skin. As the skin is retracted laterally, a lateral incision is made through the fascia lata, and the dissection proceeds in the usual fashion. Both fascial and fasciocutaneous flaps have been used to restore soft tissue deficits in patients undergoing radical parotidectomy. ^[15]

  • Through the same donor incision, fascia lata has been harvested for simultaneous temporalis tendon transfer. Attached fascia lata has also been useful in recreating the mylohyoid sling in oral floor reconstruction ^[16] and nasal lining in complex nasal defects. ^[17]

• Musculocutaneous flap: If greater amounts of bulk are needed, a larger cuff of vastus lateralis muscle may be incorporated with the anterolateral thigh flap.

• Osteofasciocutaneous flap: The lateral femoral circumflex system may be used to incorporate not only the soft tissue of the anterolateral thigh but also the lateral iliac crest bone. ^[18] The bone is supplied by an ascending branch off the lateral femoral circumflex system. The mean length of bone harvested has been 7 cm.

• Sensate flap: The anterolateral thigh flap may be made sensate by incorporating branches that derive from the lateral femoral cutaneous nerve. These branches enter the skin paddle from a superior lateral direction and must be dissected out in the subcutaneous tissue prior to incising the fascia lata.

• Thinning the flap: Primary thinning may not be advisable in Western patients. ^[19] In these situations, thinning may interrupt the connection between subdermal and suprafascial vessels and cause necrosis of the skin, particularly peripherally.

Lateral thigh free flap

As with any free tissue transfer, take measures in the immediate postoperative period to monitor flap viability and maximize chances of flap success. Two closed suction drains are typically placed in the neck but distant to the anastomosis. Different practitioners use various special antithrombotic agents and different forms of postoperative monitoring. The free lateral thigh flap requires no specific modifications of these practices. The flap is monitored closely for signs of venous congestion or arterial insufficiency; the flap should be pale pink.

Infection, hematoma, and fistula are possibilities with procedures involving the upper aerodigestive tract. Take appropriate measures to monitor and treat the patient for these entities. Encourage the patient to walk within a few days of surgery. The drains are left in place until output falls to less than 30 mL per drain per day. Occasionally, a patient is sent home with the drains still in place. In other cases, a seroma may develop after the drains are removed, and the patient must return for serial aspirations of the seroma. Although the patient is initially sore at the donor site, no long-term limitations of function should exist. Normal leg motion is encouraged as soon as the patient is able to walk postoperatively.

When the flap is used to replace skin on the face, neck, or scalp, the paler skin of the thigh usually stands out in sharp contrast to the redder skin of the head, as seen below. The shape of the flap could change postoperatively, particularly when a planned tissue protrusion is performed to fashion a neotongue. Regardless of how well designed the flap is, these folds of skin always flatten significantly.

Appearance of a healthy flap is shown after anastomosis and inset. Note the pale color in comparison to the surrounding skin.

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Anterolateral thigh free flap

Generally, no dressing is used over the donor site, although a drain is placed. The drain is removed after output falls below 30 mL per day and has turned a serosanguineous color. Antibiotic ointment is applied twice daily to the suture line. The patient is encouraged to walk by the third postoperative day.

When using the anterolateral thigh flap for restoration of tissue bulk, volume loss on the order of 8% has been noted after radiation therapy. ^[20] This would imply that some overcorrection at the reconstructive site is indicated if adjuvant radiotherapy is planned.

Lateral thigh free flap

Flap death is always a possibility with free tissue transfer. Nevertheless, success with the lateral thigh flap approaches 90-95%. At times, the PFA is unusable because of arteriosclerotic plaque. In these cases, the perforating artery may be used. Regardless, use of the PFA is generally preferable because of its large caliber and length. Greater vessel length is particularly important in positioning the flap for anastomosis in cases with large bulky flaps. If the vessels are accidentally transected during dissection but are long enough to be used for the flap, the posterior skin attachment may be left intact until the time of anastomosis. During this interval, the posterior subdermal and dermal vessels provide adequate blood flow to the skin flap.

Although the donor site is grafted with skin only on occasion, skin grafts may be lost because seromas have a tendency to develop in this area. To avoid this possibility, an anterior relaxing incision can be made, the thigh skin can be shifted posteriorly, and the skin of the secondary area can be grafted.

Anterolateral thigh free flap

As with other free flaps used in the head and neck, complications of fistula and complete or partial necrosis of the flap has been reported. Nevertheless, the flap viability rate has been reported as 97-100%. Complications at the donor site may include partial wound dehiscence, incomplete skin graft take and wound infection. Some patients may report postoperative numbness over the anterolateral thigh. Pain and weakness in the thigh may result if the deep fascia of the thigh is harvested along with the flap.

Partial necrosis of the foot and calf caused by the interruption of the descending branch of the lateral circumflex femoral artery has been reported. ^[21] In this patient, the flap vessel acted as a critical collateral for an obstructed superficial femoral artery. The authors recommend preoperative angiography of the donor leg in patients in whom a popliteal pulse is not palpable. If lower leg circulation is noted to be decreased after clamping the flap's pedicle, immediate intraoperative arterial reconstruction with a venous graft is recommended.

Lateral thigh free flap

Bulk, large surface area, and pliability make the lateral thigh flap an attractive option in head and neck reconstruction. Donor site morbidity is minimal and usually consists of a linear scar and mild-to-moderate depression in the posterolateral aspect of the leg. Very large amounts of tissue may be replaced with this flap. Nevertheless, the lateral thigh free flap is not recommended for large lateral mandibular defects or for defects of the anterior mandibular arch.

Anterolateral thigh free flap

The anterolateral thigh free flap has been associated with minimal long-term donor site complications. Typically, patients are allowed to walk after 3 days. They may experience slightly more weakness climbing stairs, but this should not be bothersome or affect daily functioning. Even when the bulk of the vastus lateralis muscle is harvested, no significant decrease in strength or range of motion (when compared to the nonoperated leg) has been found.

Similar to the above statements, a study by Nokovitch et al indicated that donor site morbidity from harvesting an anterolateral thigh free flap is low. One or more donor site sequelae were found in 39% of the study’s patients, with the patient-reported impact of these sequelae on sports activities, daily living, and work being mild or absent in 94%, 98%, and 100% of cases, respectively. The appearance of the scar was considered to be discreet or very discreet by 61% and 58.5% of surveyed patients and surgeons, respectively. ^[22]

Lateral thigh free flap

Some controversy exists as to whether the PFA itself or the third perforator is preferable to use for anastomosis. As discussed above, pedicle length is found to be too short when the third perforator is used instead of the PFA. Another debate involves the harvesting of the PFA proximal to the second perforator. Although the idea that dividing the PFA proximal to the second perforator may cause muscular weakness has been suggested, this result does not occur universally.

One report discusses a patient who had a large skin paddle (30 X 16 cm). The surgical approach involved harvesting the entire PFA proximal to the second perforator and using the second and third perforators; this was thought to give the flap the best chance for survival. The flap survived without incident, and the patient had no muscular sequelae.

Anterolateral thigh free flap

One controversy that involves the anterolateral thigh flap involves the preoperative identification of vessels. Part of the reason for the slow acceptance of the flap in the West has been the perception that the anatomy is unpredictable and dissection is difficult. Identification of a perforating vessel is problematic with a Doppler device because signals from the descending branch may be confused for a signal from a perforator. Some surgeons have advocated preoperative arteriography because of the variability of the vessel anatomy, while others feel this is unnecessary.

The acoustic Doppler has been demonstrated to not be as good as color Doppler in identifying perforators. The former has only a 40% concordance rate with anatomic dissection. ^[23]  A study by Lethaus et al reported that when anterolateral thigh flaps are being created, the precision and reliability of color Doppler ultrasonography surpasses those of a handheld Doppler device in identifying the anatomical position of the perforating arteries. With regard to locating the perforators, color Doppler ultrasonography was found to have a sensitivity and positive predictive value of 97.9% and 100%, respectively, compared with 90.5% and 80.4%, respectively, for the handheld Doppler device. ^[24]

Magnetic resonance arteriography (MRA) and conventional arteriography have their advantages and drawbacks. Unfortunately, MRA cannot reliably detect vessels less than 2 mm in diameter, and most thigh perforators fall into that category.

Intraoperative identification of perforators using an endoscope has been reported. ^[25] This has the potential of avoiding a long scar in those approximately 2% of patients that have no viable perforators.

As mentioned above, anterolateral thigh flaps may be combined with other free flaps using the chimeric or mosaic principle. This concept involves anastomosing the vessels of a second flap to a branch of the lateral circumflex femoral system. The technique is useful for large, complex wounds. The anterolateral thigh flap has been combined with fibula, radial forearm, iliac crest, groin, anteromedial thigh, and latissimus dorsi flaps. Because of its size, ease of harvest, vessel quality, and low donor site morbidity, the anterolateral thigh flap is aptly suited and has emerged the "workhorse" flap for soft tissue head and neck reconstruction.