Vastus lateralis motor nerve can adversely affect anterolateral thigh flap harvest

BACKGROUND: The vascular anatomy of the anterolateral thigh flap has been well studied, but no study has evaluated the effect of the vastus lateralis motor nerve anatomy on anterolateral thigh flap harvest. METHODS: A retrospective review was performed of all anterolateral thigh flaps from January of 2003 through December of 2004. Information regarding the motor nerve to the vastus lateralis muscle was recorded, along with its influence on anterolateral thigh flap harvest. RESULTS: Forty-three anterolateral thigh flap procedures were performed over a 2-year period. In three cases (7 percent), the course of the motor nerve to the vastus lateralis resulted in a significant modification in anterolateral thigh flap harvest. In one case, the motor nerve passed between the venae comitantes of the descending branch of the lateral femoral circumflex artery just proximal to the midperforator origin. In two cases, large skin islands were raised with two perforators included in each flap. The motor nerve passed between the two perforators in these cases. CONCLUSIONS: Two patterns of vastus lateralis motor nerve anatomy can adversely influence anterolateral thigh flap elevation. One involves the motor nerve passing through the main vascular pedicle. The other occurs when multiple perforators are required to support large flaps with the motor nerve passing between these perforators. In some cases, the course of the nerve may require transection of the nerve, with a subsequent deficit in vastus lateralis function. In similar cases, if the nerve is preserved, the vascular pedicle may require significant modification, which may possibly compromise flap perfusion.