(A512) BMI and Sex as Predictors of Anterolateral Thigh Free Flap Thickness for Oral/Oropharyngeal Reconstructions

Introduction: Pre-operative decision-making for oral and oropharyngeal defect reconstructions is crucial for surgical success. While radial forearm free flaps (RFFF) are the mainstay flap choice, anterolateral thigh free flaps (ALTFF) can also be employed, though limited by thigh thickness which can vary significantly and is often assessed subjectively by pinch testing. BMI and sex may predict ALTFF thickness and offer guidance for its use.

Methods: A retrospective observational study was performed on patients who underwent super-thin ALTFF (ST-ALTFF) and RFFF reconstruction following oropharyngeal carcinoma resection between 2020 and 2024. All patients had PET/CT scans done prior to surgery which were used to measure flap thickness. Patient sex, height, and weight were gathered at the time of the scan, and BMI was calculated. Flap thickness was defined as the perpendicular distance from superficial-most point of the intersection of the rectus femoris and vastus lateralis muscles to the overlying skin surface. Measurements were taken at the proximal 4th (A), midpoint (B) and distal 4th (C) points of the line connecting the ASIS to the patella’s superior lateral surface. Student's t-test and Pearson’s correlation test were used for data analysis.

Results: Thirty-three patients, 19 males and 14 females, met inclusion criteria. Average BMI was 25.68 with no difference between males and females (p=0.202). Fifteen (6 M, 9 F) had a BMI>25. Flap thickness was highest at point A (mean 24.15 mm) and decreased distally (B: 18.39 mm, C: 12.61 mm; p=0.004 between A and B, p=0.0025 between B and C). Females and patients with BMI>25 had thicker ALTFF at all points (Sex: A: p=0.02, B: p=0.0001, C: p=0.0001; BMI: A: p< 0.0001, B: p=0.0006, C: p=0.001). BMI and ALTFF thickness correlated positively at each point (A: r=+0.78, p< 0.0001; B: r=+0.63, p< 0.0001; C: r=+0.62, p< 0.0001).

Conclusions: In female patients and those with BMI>25, ALTFF can carry excessive adiposity, limiting its use in oral/oropharyngeal reconstruction. RFFF may be preferred despite donor site morbidity. BMI and sex are key consideration in head and neck reconstruction selection.