Anatomic variations and technical problems of the anterolateral thigh flap: a report of 74 cases.

We have transferred 74 free or pedicled anterolateral thigh flaps, including those combined with other flaps, for reconstruction of various types of defects. We report several anatomic variations of the lateral circumflex arterial system and discuss some technical problems with this flap. Septocutaneous perforators were found in 28 of 74 cases (37.8 percent), and no perforators were found in 4 cases (5.4 percent). In the 70 cases with perforators, 171 tiny cutaneous perforators (an average of 2.31 per case) were found. Musculocutaneous perforators (81.9 percent) were much more common than septocutaneous perforators (18.1 percent). Perforators were concentrated near the midpoint of the lateral thigh, and the selection of perforators as nutrient vessels for the anterolateral thigh flap was related to the length of the pedicle and the thickness of the skin flap. Anatomic variations of the branching pattern of perforators were classified into eight types. Flaps with perforators that arise directly from the profunda femoris artery are difficult to combine with other free flaps. Because the perforators are extremely small and tend to thrombose soon after congestion develops, these flaps are difficult to salvage with recirculation surgery. Therefore, several perforators should be included with the flap, if possible. The descending artery of the lateral circumflex femoral artery was always accompanied by two veins with different back-flow strengths. Therefore, veins for microsurgical anastomosis must be chosen carefully. Because it is nourished by several perforators arising from the descending artery, the vastus lateralis muscle can be combined with the anterolateral thigh flap. However, splitting the muscle longitudinally without harvesting its blood supply is complicated because its fibers are oblique. The rectus femoris muscle can also be combined with the anterolateral thigh flap, but its pedicle is short and its origin is very near the site of anastomosis. When the anterolateral thigh flap is combined with the tensor fasciae latae musculocutaneous flap, the large skin area of the lateral part of thigh can be transferred to repair the massive defects. The anterolateral thigh flap has many advantages and can be used to reconstruct many types of defect. However, anatomic variations must be considered if the flap is to be used safely and reliably.