Body Mass Index Is Associated With Myocutaneous Free Flap Reliability: Overcoming the Obesity Obstacle With a Proposed Clinical Algorithm to Identify and Manage High-Risk Patients Undergoing Gracilis Free Flap With Skin Paddle Harvest.

[INTRODUCTION] The purpose of this study was to evaluate the role of body mass index (BMI) in predicting postoperative complications following myocutaneous free flap transfer. In addition, we sought to identify certain body composition variables that may be used to stratify patients into low- versus high-risk for gracilis myocutaneous free flap with skin paddle failure.

[METHODS] Using the National Surgical Quality Improvement Program database, we collected data for all patients who underwent myocutaneous free flap transfer from 2015 to 2021. Demographic data, medical history, surgical characteristics, and postoperative outcomes, including complications, reoperations, and readmissions, were collected. Body mass index was correlated with outcome measures to determine its role in predicting myocutaneous free flap reliability. Subsequently, we retrospectively obtained measurements of perigracilis anatomy in patients who underwent computed tomography angiography bilateral lower extremity scans with intravenous contrast at our institution. We compared body composition data with mathematical equations calculating the potential area along the skin of the thigh within which the gracilis perforator may be found.

[RESULTS] Across the United States, 1549 patients underwent myocutaneous free flap transfer over the 7-year study period. Being in obesity class III (BMI ≥40 kg/m2) was associated with a 4-times greater risk of flap complications necessitating a return to the operating room compared with being within the normal BMI range. In our computed tomography angiography analysis, average perigracilis adipose thickness was 18.3 ± 8.0 mm. Adipose thickness had a strong, positive exponential relationship with the area of skin within which the perforator may be found.

[CONCLUSIONS] In our study, higher BMI was associated with decreased myocutaneous free flap reliability. Specifically, inner thigh adipose thickness can be used to estimate the area along the skin within which the gracilis perforator may be found. This variable, along with BMI, can be used to identify patients who are considered high-risk for flap failure and who may benefit from additional postoperative monitoring, such as the use of a color flow Doppler probe and more frequent and prolonged skin paddle monitoring.