Factors Associated With Venous Complications in Lower Extremity Free Flap Reconstruction: A Multivariate Analysis

Due to their dependent location, lower extremity (LE) free flaps (FFs) are at increased risk for venous complications. This study analyzes risk factors of venous complications in LE FFs.

A single-center retrospective review was conducted of adult patients undergoing LE FF reconstruction from 2016 to 2025. Variables included demographics, wound and operative characteristics, and the number of venous anastomoses. The primary outcome was venous complications, defined as a composite variable encompassing venous congestion, flap loss due to venous causes, and flap hematoma.

The cohort consisted of 370 patients undergoing LE FF reconstructions. Single venous anastomosis was used in 123 (33.2%) patients, and dual venous anastomoses were used in 247 (66.8%). The overall venous complication rate was 7.3%. In the multivariate model, the only independent predictor for venous complication was the use of the superficial venous system as the sole drainage route (odds ratio, 14.5; P = 0.013). Age, sex, comorbidities, flap type, use of a vein inside versus outside of the zone of injury, and dual versus single venous anastomosis were not significantly associated with the venous complication rate.

Compared with anastomoses to deep veins, the use of the superficial venous system as the sole venous drainage may lead to an increased risk of venous complications. On the other hand, routine performance of a second venous anastomosis does not decrease the risk of venous congestion. It may be safe to use veins within the zone of injury when necessary.