Is Body Mass Index Associated With Fibula Free Flap Skin Paddle Thickness?

Body mass index (BMI) is often used as a surrogate measure to judge the thickness of soft tissue free flap thickness. The fibula free flap (FFF) skin paddle is harvested from a distal location less affected by central adiposity. No prior studies have examined the relationship between BMI and fibula skin paddle thickness.

The study purpose was to measure the association between BMI and fibula skin paddle thickness.

This is a cross-sectional study of patients who were evaluated for FFF reconstruction at the University of Washington, Department of Oral and Maxillofacial Surgery from August 2024 through September 2025. Exclusion criteria were prior lower leg surgery or trauma below the knee and above the ankle.

The primary predictor was BMI (kg/m²).

The primary outcome was fibula skin paddle thickness (mm).

Covariates were age, sex, primary diagnosis, fibula length, posterior septum length, and leg circumference.

Appropriate univariate, bivariate, and multivariate statistics were computed. The level of statistical significance was set at P < .05.

The sample consisted of 45 subjects with a mean age of 52.3 (standard deviation [SD] = 19.4) and a mean BMI of 26.7 (SD = 7.6). 28 (62.3%) were male, and the mean skin paddle thickness was 6.2 mm (SD = 3.0). There was no significant linear correlation between skin paddle thickness and BMI (r = 0.12; P = .4). Only female sex was associated with a significantly greater mean skin paddle thickness (7.5 vs 5.5 mm, P = .04) and a higher frequency of thick (≥10 mm) skin paddles (23.5 vs 3.6%, P = .04).

There was no statistically significant association between BMI and fibula skin paddle thickness in this sample. Because of its variable relationship with body composition, the fibula skin paddle should be assessed both clinically and radiographically to obtain the most accurate thickness estimate.