Versatility of the Pedicled Anterolateral Thigh Flap - The Clinics

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678 Neligan & Lannon Fig. 1. The lateral circumflex artery (A), a branch of the profunda femoris, has a lateral (ascending) branch (B) that supplies the tensor fasciae lata muscle (TFL) and a descending branch (C) that supplies the anterolateral thigh flap. This vessels runs under rectus femoris (RF) and then in the septum, between rectus femoris and vastus lateralis (VL). recognizing that this method may not always be accurate. 15 The flap can be raised to include any of the elements supplied by the vasculature. It can incorporate muscle (vastus lateralis), fascia, and skin. The choice of which tissues to include will be dictated by the reconstructive requirements. The technique may be modified accordingly. For many of the reconstructive applications that a pedicled anterolateral thigh flap can address in the lower abdomen, the fascial element of the Fig. 2. A line drawn between the anterior superior iliac spine and the lateral border of the patella is the surface marking of the septum between rectus femoris and vastus lateralis. The midportion of this line is where perforators will be found. flap can be important, which is particularly the case when reconstructing through abdominal wall defects. Often, the amount of fascia required is larger than the amount of skin required. If this is the case, an excess of fascia over skin can easily be harvested (Fig. 3). Vascularized fascia lata in abdominal wall reconstruction is said to have the advantage of preventing adhes between the fascia and the abdominal viscera. 16 If no fascia is required for the reconstruction, then a skin-only flap can be designed and the fascia simply incised around the perforators (Fig. 4). Furthermore, if muscle is a required element of the reconstruction, the flap can be raised as a myocutaneous flap incorporating the vastus lateralis muscle. The technique of dissection will depend on what elements are being included with the flap. The dimensions of the flap will obviously be dictated by the size of the defect to be reconstructed. However, the vascular pedicle of the anterolateral thigh can carry a large flap (up to 30 cm). To perfuse such a large skin paddle, however, more than 1 perforator may need to be harvested with the flap. If multiple perforators are available, it is judicious to sequentially clamp them so as to ensure that the selected perforators will perfuse the flap (see Fig. 4). Pedicle length can also be particularly important when the flap is being designed as a pedicled flap; the longer the pedicle, the greater the arc of rotation. Preoperative imaging may be particularly helpful when planning a pedicled anterolateral thigh flap because the location of the perforator has a bearing on pedicle length and, therefore, on the arc of rotation of the flap. A distally placed perforator, the C perforator according to Yu’s classification, can add considerable length and can be chosen if it is of appropriate size. The more distal perforators, however, tend to Fig. 3. The amount of fascia harvested with this flap exceeds the amount of skin. This picture shows the excess thigh fascia being sutured to the abdominal wall fascia.
Fig. 4. In this suprafascial flap dissection, 2 perforators have been isolated. A microvascular clamp has been placed on the proximal perforator to ensure that the distal perforator can perfuse the whole flap. have a longer intramuscular course. Although the extra pedicle length gained from dissecting these perforators may be desirable, the amount of intramuscular dissection can be an important issue. Regardless of the position of the perforator, size is important and the perforator needs clinical evaluation to ensure that it can adequately perfuse the flap. As already mentioned, if ever there is any doubt, sequentially clamping the perforators (see Fig. 4) can be a good way to determine which perforator offers the best perfusion. The width of the flap is also important because it will determine whether or not the donor site will need a skin graft or whether it can be closed by direct approximation. Direct closure is desirable because a skin graft in this area is unsightly and not always well tolerated by patients. Although it is generally accepted that a width of 8 cm can usually be closed directly, it has been the authors’ experience that much wider defects can be closed directly. If the flap does not contain fascia, it is generally much easier to close the donor defect than when the fascia has been harvested with the flap because the fascia contains and constrains the thigh musculature, which, when fascia has been harvested with the flap, tends to bulge and make closure more difficult. Regardless of whether or not fascia has been harvested with the flap, penetrating towel clamps can be used to temporarily approximate the wound edges (Fig. 5) allowing sufficient tissue creep to facilitate closure. Care must be exercised, however, in situations where patients are unable to report symptoms that might indicate too tight a closure. The authors have encountered 2 cases of compartment syndrome, in the presence of epidural anesthesia, that was caused by a closure that was too tight. 17 Pedicled Anterolateral Thigh Flap 679 Fig. 5. Penetrating towel clamps are used to temporarily approximate the wound edges to facilitate closure. If closure is this tight, it is important to ensure that patients are in a fit condition to report symptoms of compartment syndrome. ARC OF ROTATION The proximally pedicled anterolateral thigh flap will easily reach the lower abdomen and perineum. 2,18e20 As already mentioned, choosing a more distal perforator increases the length of the pedicle and, therefore, the arc of rotation. However, size is important when choosing an appropriate perforator. Choosing a distal perforator simply because of position and not because of size is not advised. The arc of rotation is also determined by the method by which the flap is transferred. The lateral circumflex femoral artery is a branch of the profunda femoris. The artery comes off the lateral aspect of the profunda at a point that is medial to the proximal segment of the rectus femoris muscle. It runs under that muscle and eventually runs between the rectus femoris and vastus lateralis muscles. To dissect the pedicle to its origin, the rectus femoris must be retracted. Tunneling the flap under the rectus femoris (Fig. 6) increases its arc of rotation and allows the flap to reach the perineum and lower abdomen. For more lateral defects of the lower abdomen or thigh, tunneling under rectus femoris offers no advantage. In fact it may shorten the arc of rotation in that direction. Sometimes dividing the main pedicle to rectus femoris, as the flap is tunneled under this muscle, will significantly increase the arc of rotation. However, caution is required in relation to these maneuvers because ischemic damage to the rectus femoris muscle may result from division of its main pedicle, 21 and denervation may result from tunneling under its proximal third because it is innervated by 2 to 4 nerve branches entering posteromedially in this region. 22 In addition, the saphenous vein is at risk during medial subcutaneous tunnelling. 23 If rectus femoris pedicle ligation is being considered intraoperatively, it is prudent to clamp the pedicle and observe for muscle vascularity before pedicle division. The donor site is closed primarily in layers or
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Versatility of the Pedicled Anterolateral Thigh Flap - The Clinics

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