Study of the neural and vascular anatomy of the anterolateral thigh flap

The purpose of this study was to perform a detailed investigation of the vascular and neural structures of the anterolateral thigh (ALT) flap, with emphasis on the peripheral neurovascular system of the subcutaneous adipofascial layer. Methods: Ten cadavers were examined after injection of latex into the bilateral external iliac arterial system. The nutrient vessels of the femoral cutaneous nerves and the relationship between these vessels and the adjacent tissue were studied. Results: The intrinsic and extrinsic neurocutaneous vascular systems surrounding the cutaneous nerves in the deep adipofascial layer were explored. The extrinsic neurocutaneous vascular system consisted of chain-like anastomoses formed by segmental arteries derived from perforators and revealed a distinct axial course along the nerves. The first segmental artery of the extrinsic neurocutaneous system was found to be the longest and to have the greatest diameter. The three-dimensional vascular structure of the ALT flap resembled a tree, in that the nutrient vessels arborised in each layer with their length and diameter decreasing from the deep adipofascial layer to the superficial adipofascial layer. Two categories of branch vessels connect the suprafascial plexus and subdermal plexus in the ALT flap: (1) large branches derived directly from the perforator ascend obliquely or vertically to the skin and (2) small branches arise from the nerve's nutrient artery and ascend to the skin. Conclusions: The ALT flap is ideal for soft-tissue reconstruction in the Asian population. Preservation of the large branch vessels ensures flap survival during primary defatting, allowing for improved contour in single-stage reconstructions. It is also possible to design a proximally pedicled neurocutaneous flap based on the cutaneous nerve in the thigh and its corresponding vascular system. This neurocutaneous flap may offer a novel advantage for sensate reconstruction of the perineum.