Revisiting the variants of the Anterolateral Thigh Flap based on 3D Microscopic Vascular Investigations

INTRODUCTION The anterolateral thigh (AL) is a versatile donor site for reconstructive surgery, well-known to be supplied by perforators from the lateral circumflex femoral artery (LCFA). However, a more detailed understanding of its microvascular architecture throughout the different tissue layers, from the deep fascia (FL) to the skin could lead to the description of useful surgical variants. This study provides a comprehensive and quantitative 3D-assessment of the vascular microarchitecture of the full-thickness flap and explores its potential implications. MATERIALS AND METHODS Twenty-two FL-to-skin flaps were harvested from fresh frozen cadaver limbs. The investigations encompassed LCFA distribution (N=11), vascular microarchitecture (N=5), and perforasomes (N=6). Using Angiofil-latex injection and X-ray microfocus computed tomography (microCT), perforator origin and distribution were evaluated, alongside quantification of vascular volume in each tissue layer and branching patterns at a microscopic level. RESULTS After confirming the predominance of LCFA-derived perforators in the ALT, microCT revealed four distinct interconnected vascular networks in the subfascial, intrafascial, suprafascial and subdermal planes. Strikingly, perforator vessels give rise to a dense network inside the FL, featuring arterioles with a mean radius of 55.4 ± 28.5µm and a volumetric density of 0.031 ± 0.032mm³/mm². This often neglected intrinsic plexus complements the well-known suprafascial and subdermal plexuses. Quantitative evaluations demonstrated a microvascular density of 67.5 ± 23.2% in the deep FL and suprafascial fat, with the most abundant vessels in the intrafascial and subdermal plexuses. The fascia superficialis (FS) was consistently localized between the territories supplied by suprafascial and subdermal plexuses, respectively. CONCLUSION This refined understanding of the 3D-microvascular architecture of the ALT donor site supports the potential design of adiposofascial flaps with a preserved perfusion of the FL and deep fat layer. This latter vascular carrier, including both a thick mechanical supportive tissue (FL) and filling fatty tissues, has potential applications for tissue engineering, with minimal donor site morbidity.