Risk factors for microvascular free flaps in pediatric lower extremity trauma

Purpose: There is a dearth of literature dedicated to specifically evaluating the use of free flap reconstruction in pediatric lower extremity traumas. This study aims to identify specific risk factors for flap failure in pediatric lower extremity trauma reconstruction. Methods: Retrospective review of 53 free flaps in our lower extremity database (1979-2017) identified all free flaps performed for traumatic reconstruction in children <18 years of age at our institution. Results: Fifty-three free flaps (11.1%) were performed in 49 pediatric patients. The majority of patients were male (69.8%). Arterial injury was present in 19 patients (35.8%) and was associated with significantly higher flap failure rates compared to patients without arterial injury (36.8% vs 8.8%, P = 0.020) with RR = 6.0. This was again found to be true on multivariable logistic regression controlling for age, sex, flap type, and degree of arterial or venous mismatch (RR = 53, P = 0.016). Analysis of anastomotic vessel sizes revealed significantly increased risk of flap failure with increasing degree of arterial size mismatch on logistic regression (RR = 6.1, p =.02). Similar analysis for venous data was performed and revealed trending towards similar findings without reaching statistical significance (P =.086); however, the presence of any venous size mismatch was associated with significantly increased risk of flap failure on χ² analysis (P = 0.041). Conclusion: Free flap reconstruction in the pediatric trauma population is safe with similar survival outcomes when compared to the adult population. Arterial injury and vessel size mismatch were associated with significantly higher flap failure rates in this population. Level of Evidence: Level III.