Lessons Learned From 40 Years of Traumatic Lower Extremity Free Flaps: Inflow, Outflow, Takebacks, and Failures
John T. Stranix, MD1, Z-Hye Lee, MD1, Adam Jacoby, MD1, Lavinia Anzai, MD1, Joseph Ricci, MD1, William J. Rifkin, BA1, Tomer Avraham, MD2, Vishal D. Thanik, MD1, Pierre B. Saadeh, MD1, Jamie P. Levine, MD1.
1NYU Langone Health, New York, NY, USA, 2Yale University School of Medicine, New Haven, CT, USA.
PURPOSE: Despite advances in microsurgery, higher free flap complication rates in lower extremity trauma reconstruction have persisted. We evaluated our experience to identify factors associated with microsurgical outcomes.
METHODS: Retrospective review of 806 lower extremity flaps (1976-2016); 481 soft tissue flaps for below knee trauma met inclusion criteria. Primary outcome measures were perioperative flap complications (takebacks, partial failures, and total failures). Univariate and multivariate regression analysis was performed.
RESULTS: Muscle flaps predominated (75%) over fasciocutaneous (25%). Major perioperative complications occurred in 111 flaps (23%): 71 takebacks (15%); 45 partial losses (9%); 37 complete losses (8%). Time from injury to coverage was divided into acute, subacute, and chronic subgroups for analysis: <10 days (33%), 11-90 days (35%), and >90 days (32%). The acute period demonstrated higher flap failure rates (p=0.007) compared to the subacute and chronic groups. Comparing our early, middle, and most recent flaps, a learning curve was observed with more takebacks (p=0.033) and failures (p=0.038) among our first 160 flaps. Decreasing arterial runoff directly correlated with increased complications (p=0.048): compared to 3-vessel legs, 2-vessel had increased flap failures (RR=2.08,p=0.041), and 1-vessel had even higher failure risk (RR=3.67,p=0.001). Two veins reduced complications (p=0.042), but subgroup analysis showed no effect on fasciocutaneous flap outcomes. Two-vein muscle flaps, however, had fewer complications (RR=0.37,p=0.001) and flap failures (RR=0.36,p=0.017). Vein size mismatch >1mm was also associated with increased total failure risk (RR=2.28,p=0.041). Fasciocutaneous flaps had higher takeback rates than muscle (p=0.004) and more frequently occurred within 48 hours postoperatively (p=0.012). Despite higher takeback rates, however, fasciocutaneous flaps were much more likely to be successfully salvaged than muscle-based flaps (RR=9.42,p=0.001). A similar effect was observed among muscle flaps with skin paddles: musculocutaneous flaps were taken back earlier (p=0.036) and salvaged more often (p=0.024) than muscle-only flaps.
CONCLUSION: Lower extremity trauma reconstruction remains challenging and should be tailored to each individual patient. Our experience highlights multiple microsurgical factors associated with perioperative outcomes. In contrast to traditional dogma, our acute time period demonstrated higher free flap complication rates. The degree of arterial injury provided a surrogate marker for injury severity and correlated with increased free flap complications. A second venous anastomosis was protective against flap complications, particularly among muscle flaps. Flap type and design were also found to be important as fasciocutaneous flaps had higher salvage rates compared to muscle after takeback, and this was also true among muscle flaps with skin paddles versus those without. The demonstrated prognostic value of these findings warrants reconstructive consideration when planning free flap coverage of lower extremity trauma.
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