Segmental anatomy of the vastus lateralis: Guidelines for muscle-sparing flap harvest

Background: The vastus lateralis muscle is a versatile donor site for pedicled and free flaps that, despite great potential, remains unpopular. Although the muscle is classically described as a single belly, evidence exists for a more complex morphology. The aim of this study was to investigate the segmental anatomy of the vastus lateralis muscle and the feasibility of selective flap harvest. Methods: Ten cadaveric lower limbs were investigated. Muscular partitions were identified according to morphologic architecture, vascular supply, and nerve supply; guidelines for selective flap harvest were described. Twenty-three segmental vastus lateralis (n = 14) or chimeric anterolateral thigh-vastus lateralis flaps (n = 9) were raised based on neurovascular segmental supply, and used as noninnervated free flaps for reconstruction of moderate and large defects of the head and neck, trunk, or lower limbs. Intraoperative electrostimulation was used to confirm segmental innervation. Lower limb function was evaluated through the Lower Extremity Functional Scale. Results: The authors clearly identified three anatomical partitions, which receive a constant segmental neurovascular supply, and two aponeuroses. The authors successfully applied the proposed guidelines for flap harvesting to all 23 patients. Intraoperative electrostimulation confirmed functional integrity of both the flap and the spared partitions. All muscle flaps survived. Donor-site morbidity was negligible, with comparable mean preoperative and postoperative Lower Extremity Functional Scale values (67.7 versus 67.4; p > 0.05). Conclusions: This study provides detailed knowledge on the morphologic and neurovascular anatomy of the vastus lateralis muscle, which supports the authors' guidelines for selective flap harvesting. The technique described is safe and minimizes surgical damage.