Optimizing Venous Outflow in Lower Extremity Free Flaps: Are Two Veins Better Than One?
John T. Stranix, MD, Lavinia Anzai, BS, Z-Hye Lee, MD, Adam Jacoby, MD, Pierre B. Saadeh, MD, Vishal D. Thanik, MD, Jamie P. Levine, MD.
Wyss Department of Plastic Surgery, NYU Langone Medical Center, New York, NY, USA.
Purpose: Venous compromise is the most common reason for perioperative free flap complications. The dependent nature of the lower extremity likely increases this risk, especially following significant lower extremity trauma with superficial or deep venous injury and immobilization of the soleal muscle venous pump. The benefit of a second venous anastomosis, however, remains unclear in lower extremity trauma free flap reconstruction and warrants further investigation.
Methods: Retrospective institutional registry review of 2,898 free flaps performed between 1979-2016 identified 806 lower extremity reconstructions; 361 soft tissue flaps performed for Gustilo IIIB/C coverage met inclusion criteria. Patient demographics, flap characteristics, and outcomes were examined using Chi-square, t-tests, and logistic regression.
Results: Muscle flaps predominated (n=287, 79.9%) compared to fasciocutaneous (n=72, 20.1%). Single-vein outflow was more common (76%) than dual-vein (24%). Majority of recipients were in deep venous system (89%) vs. superficial (6.0%) or both (3.6%). Anastomoses were primarily end-to-end (92%); venous coupler used for 19%; 3.6% required vein grafting. Fasciocutaneous flaps were more likely to have two veins performed (p<0.001). Complications occurred in 143 flaps (39.8%) with 37 partial flap losses (10.3%), and 31 complete flap losses (8.6%). Emergent return to the operating room for vascular compromise occurred in 45 flaps (12.4%); most commonly for venous insufficiency (n=26, 57.8%), arterial (n=14, 31.0%), or undetermined (n=5, 11.1%). Compared to single vein flaps, two venous anastomoses were associated with reduced complications (p=0.007), partial flap failures (p=0.006), and any flap failure (p=0.048). Multivariable regression analysis controlling for age, sex, flap type, vein size mismatch >1mm, bone gap presence, and time since injury demonstrated two veins to be protective against complications (RR=2.58, p=0.009). Subset regression analysis by flap type demonstrated no significant association between 1 vs. 2 vein outflow and complications among fascoicutaneous flaps, however, muscle flaps with two veins demonstrated even more significant reduction in complications (RR=3.92, p=0.005). Regression analysis also found an increased total failure rate among flaps with a >1 mm vein size mismatch (RR=3.02, p=0.038). No statistically significant association was found between recipient vein size (larger or smaller) relative to flap vein size and complication rates (p=0.324), takeback rates (p=0.771), or flap failure (p=0.693).
Conclusion: Flaps with two venous anastomoses demonstrated reduced complication rates compared to single-vein flaps. Venous size mismatch >1mm was also associated with increased complication rates. While fasciocutaneous flaps more commonly had second veins performed, the protective effect was primarily driven by improved outcomes among muscle flaps with two veins. These results suggest beneficial effects of both two-vein outflow and matched vessel diameter, particularly among muscle-based flaps, providing evidence for preferential use of two matched venous anastomoses when possible for free flap reconstruction of lower extremity trauma.
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