Improving the outcome of distally based anterolateral thigh flap reconstruction: New classification and surgical guidelines

The distally based anterolateral thigh (dALT) flap is associated with a high incidence of venous congestion. This study aimed to investigate factors associated with vascular compromise to improve the outcomes.We retrospectively analyzed 41 dALT flap reconstructions performed between November 2010 and February 2023. The dALT flap was classified into type I, II, or III based on the origin (the descending, oblique, or transverse branch) of the chosen perforator. The distance from the pivot point to the superolateral patella, pedicle length, flap reach, complications, and loss rates were analyzed to identify different dALT flap characteristics.The type Ⅰ flap had a shorter pedicle length (type Ⅰ vs. type Ⅱ, p = 0.000; type Ⅰ vs. type Ⅲ, p = 0.000) that primarily reached closer regions (distal third of the thigh anterior/lateral knee). Pedicle lengths were similar between type Ⅱ and Ⅲ flaps (p = 1.000), most of which reached more distal regions (medial/posterior knee or proximal third of the leg). However, the type Ⅲ flaps had a higher complication rate and flap loss rate, although no significant differences were observed (complication rate, p = 0.094; flap loss rate, p = 0.071).To achieve more desirable outcomes using the dALT flap, preoperative assessment of flap pedicle length and proper intraoperative maneuvers that avoid compromising the reverse blood circulation are necessary.