Cross-sectional Vascularization Pattern of the Adipofascial Anterolateral Thigh Flap for Application in Tissue-engineered Bone Grafts

Abstract

Background: As part of the engineering of bone grafts, wrapping constructs in well-vascularized tissue, such as fascial flaps, improves bone formation. Our aim was to understand the cross-sectional vascularization pattern of human adipofascial flaps for this application. Methods: Seven adipofascial anterolateral thigh (ALT) flaps were harvested from five human cadaveric specimens. Axial vessel density was analyzed by immunohistochemistry and quantitative histology. Results: We found a high density of blood vessels directly superficial to and close to the fascia. A secondary plexus in between this first suprafascial plexus and the subdermal plexus was also identified. In all specimens, this second plexus showed less vascular density, and appeared to be at a constant level within the suprafascial fat throughout the flaps. The peak measurements for this secondary plexus varied between 1.2 and 2 mm above the deep fascia, depending on the donor’s body mass index. Conclusions: Quantitative immunohistochemistry is a reliable method to quantify and locate vessel density in an adipofascial flap. This is vital information before wrapping nonvascularized material into such a flap to estimate the inosculation potential of these vessels and likelihood of survival of the tissue. To profit from both suprafascial vascular plexuses, a correlation between subcutaneous tissue thickness and distance of the second plexus to the fascia should be further investigated. For the moment, we recommend maintaining at least 2–3 mm of subcutaneous fatty tissue on the fascia, to profit from both plexuses. Engineered constructs should be wrapped on the superficial medial side of the fascial flap to enhance vascularization.