The Effect of Positive Post-Debridement Cultures on Local Muscle Flap Reconstruction of the Lower Extremity

Purpose

 Local muscle flaps are a powerful reconstructive option for wound coverage in the distal lower extremity, particularly in high-risk patients who are poor candidates for free tissue transfer.¹ At our institution, chronic and infected wounds are managed with serial debridement prior to definitive reconstruction.²This study investigates the relationship of positive post-debridement cultures and flap closure rates at 90 days. 

 Methods and Materials

 A retrospective review of patients undergoing local muscle flap coverage of chronic distal lower extremity wounds between 2006 and 2012 was performed. Prior to flap coverage, all patients were managed with serial debridements until negative post-debridement cultures were obtained. In some cases, post-debridement cultures remained positive or exhibit delayed culture growth in the day(s) following closure. Data recorded includes demographics, flap type/location, culture data, and closure at 90 day follow-up. Statistical analysis was performed via univariate and multivariate linear regression.

 Results

 Of 76 patients, 60 patients met the inclusion criteria with minimum 90 day follow-up. Flaps performed included flexor digitorum brevis (n=10), abductor digit minimi (n=14), extensor digitorum brevis (n=2), abductor hallucis brevis (n=14), extensor hallucis longus (n=1), gastrocnemius (n=16), and peroneus longus (n=3). 17 patients (28.3%) had failure of flap closure and 22 patients (36%) had positive post-debridement cultures.  On univariate analysis, positive post-debridement cultures (OR:20.4, CI95%:4.7-88.3, p<0.001), smoking (OR:3.7, CI95%:1.1-12.1, p=0.03), and multi-drug resistant bacteria (OR:3.8, CI95%:1.1-13.2, p=0.03) were significant predictors of failure at 90 days.  Multivariate analysis identified only positive post-debridement culture (OR:29.6, CI95%:3.6-246.4, p=0.002) and smoking (OR:8.9, CI95%:1.4-57.6, p=0.02) as independent predictors of non-closure at 90 days. 

 Conclusion

 In this series of local muscle flap coverage of distal lower extremity wounds, positive post-debridement cultures were a strong independent predictor of failure. This may result in the need for further complex reconstruction or amputation and demonstrates the importance of serial debridement to negative cultures prior to definitive coverage in this patient population.