Two Veins Reduce Muscle Free Flap Complications in Lower Extremity Reconstruction
John T Stranix, MD1; Z-Hye Lee, MD1; Lavinia Anzai, MD1; Adam Jacoby, MD1; Josh Mirrer, MD1;
Tomer Avraham, MD2; Pierre B. Saadeh, MD1; Jamie P. Levine, MD1; Vishal D Thanik, MD1
1 NYU Langone Medical Center, New York, NY; 2Yale School of Medicine, New Haven, CT
Background: Venous insufficiency is the most common culprit behind free flap failure. Considering that the dependent position of the lower extremity predisposes to venous congestion at baseline, we investigated the effect of a second venous anastomosis on free flap outcomes in lower extremity trauma reconstruction.
Methods: Retrospective review of 806 lower extremity free flap reconstructions (1979-2016); 481 soft tissue flaps performed for below knee trauma reconstruction met inclusion criteria. Primary outcome measures were perioperative complications. Multivariable regression analysis controlled for: age, sex, time to coverage (<7 days, 8-90 days, >90 days), and flap type (muscle vs. fasciocutaneous).
Results: Lower leg injuries (n=361) were more frequent than foot/ankle (n=165), and muscle flaps predominated (n=362) compared to fasciocutaneous (n=119). Time from injury to coverage was divided into acute (<7 days, 29%), subacute (8-90 days, 40%), and chronic (>90 days, 32%). Single-vein outflow was more common (n=354) than two-vein (n=127). Two-veins were associated with fasciocutaneous flaps (p<0.001), foot/ankle injuries (p=0.023), and the subacute time period (p=0.002). Complications occurred in 191 flaps (39.7%): 71 takebacks (15%), 45 partial losses (9%), 37 complete losses (8%). Takeback indications were most commonly for venous congestion (48%), followed by arterial compromise (31%), unknown (10%), and hematoma (10%). Overall, regression analysis demonstrated two veins to be protective against complications (RR=0.628,p=0.042) and partial flap failures (RR=0.281,p=0.019). Interestingly, subgroup analysis by flap type demonstrated no effect of venous outflow type on fasciocutaneous flap outcomes. Among muscle flaps, however, two-vein flaps had fewer complications (p<0.001), takebacks (p=0.047), partial flap failures (p=0.001), and any flap failure (p=0.012). On regression analysis, muscle flaps with a second venous anastomosis were protected against complications (RR=0.366,p=0.001), partial flap failure (RR=0.078,p=0.013), and any flap failure (RR=0.361,p=0.017).
Conclusion: While two venous anastomoses reduced the overall risk of complications among lower extremity free flaps in our cohort, this finding was driven by the strong protective effect of two-vein outflow among muscle-based flaps. One-vein muscle flaps had 2.7 times higher risk of complications overall and a 12.8 times higher risk of partial flap failure. These results provide evidence for performing a second venous anastomosis when feasible, particularly among muscle flaps, for lower extremity trauma reconstruction.
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