Analysis of Anastomotic Venous Factors in Traumatic Lower Extremity Injuries Reconstructed by Free Flap.

Background Venous thrombosis has been shown to be the most frequent cause of free flap failure in traumatic lower extremity injuries. However, the roles of various anastomotic venous factors, including venous anastomosis (end-to-end (ETE) or end-to-side (ETS)), venous outflow (one vein or two veins), and recipient venous selection (deep or superficial vein), remain unclear. This retrospective study aims to investigate factors contributing to microvascular complications in patients with lower extremity Gustilo type IIIB/IIIC injuries reconstructed by free flap with a focus on the three abovementioned venous factors. Methods A total of 44 flap treatment outcomes of 41 patients with these injuries from 2015 to 2020 were assessed according to the three venous factors (type of anastomosis, venous outflow, and vein selection). Results The average patient age was 52 years, with the majority (75.6%) being male. Eight patients (18.2%) returned to the operating room due to venous thrombosis, and five patients (11.4%) experienced total flap failure. The following factors were suspected to have contributed to venous thrombosis: vein size mismatch (n = 2) and recipient vein insufficiency possibly due to post-traumatic vessel disease (PTVD) (n = 6). End-to-side (ETS) anastomoses showed lower venous thrombosis rates than end-to-end (ETE) anastomoses (6.3% versus 25%, p = 0.22), two-vein outflows had lower rates than one (8.3% versus 30%, p = 0.07), and deep veins had the lowest thrombosis rates (7.7%), whereas superficial veins had the highest (38.5%). Conclusion The key venous factors in preventing venous thrombosis include using as many two-vein ETS anastomoses as possible to deep recipient veins.