Height and weight predict cross-sectional area of the peroneus brevis and longus tendons: Magnetic resonance imaging-based analysis of 164 adults.

Abstract

To determine whether height, weight and body mass index (BMI) are associated with the cross-sectional area of the peroneus brevis and longus tendons on magnetic resonance imaging (MRI). Understanding these associations may assist in autograft selection and evaluation of residual tendon function after graft harvest. This retrospective study included 164 adult patients (mean age 41.6 ± 15.7 years; 52% female) who underwent 3T ankle MRI between 2018 and 2024. Patients with peroneal tendon pathology (e.g., split tears, tendinosis), prior surgery or artefacts (e.g., motion or metal-related signal loss) were excluded. Cross-sectional areas were measured 1 cm above the lateral malleolus on axial proton density-weighted images. Height and weight were obtained from pre-MRI exam documentation. Associations with tendon cross-sectional area were evaluated using multivariable linear regression models adjusted for age and side. Mean cross-sectional areas were 14.0 ± 4.2 mm² for the peroneus brevis and 19.3 ± 4.7 mm² for the peroneus longus. Peroneus brevis area was significantly associated with height (<i>β</i> = 12.9 mm²/m, <i>p</i> < 0.001) and age (<i>β</i> = 0.06 mm²/year, <i>p</i> < 0.001). Peroneus longus area was associated with weight (<i>β</i> = 0.07 mm²/kg, <i>p</i> = 0.01). No significant associations were found with BMI. All findings were robust in sensitivity analyses. Height and weight are reliable predictors of peroneal tendon size; BMI is not. MRI is a standardised, noninvasive tool for individualised graft planning and assessment of postoperative tendon integrity. These findings may assist in autograft planning and in evaluating residual tendon function after graft harvest. Level III.