Iliotibial band syndrome: Can the lateral femoral epicondyle play a role? An anatomic study of individual variation in epicondyle prominence

Abstract

Background. A prominent lateral epicondyle is a proposed contributor to iliotibial band friction syndrome, an overuse injury characterized by local soft tissue inflammation at the distal lateral knee. However, little is known about the variability in lateral epicondyle prominence. We sought to describe normal variation in prominence and determine a reliable measurement method on 3-dimensional imaging. Methods. Surface models of 165 distal femurs under age 40 (81 female, 84 male; 85 black, 80 white, age 28.7 years, SD 7.6) were created with a 3-dimensional laser scanner. Percent prominence was defined by lateral epicondyle prominence divided by lateral condyle anterior-posterior length and multiplied by 100. Variation in epicondyle prominence by sex, race, age, height, and BMI were calculated. Inter-rater and intra-rater reliability for epicondyle measurements were determined. Results. Inter-rater (ICC = 0.91) and intra-rater reliabilities (ICC = 0.94) for epicondyle prominence were high. Mean lateral epicondyle prominence is 7.9 mm (SD 1.1, range 5.5 - 11.0 mm) and mean percent prominence is 12.3% (SD 3.5). After controlling for side, height was weakly associated with epicondyle prominence (p = 0.002) but not percent prominence (p = 0.24). No association was observed between epicondyle dimensions and age, BMI, sex or race in the multivariate model (p < 0.05). Conclusions. Lateral epicondyle prominence can be reliably measured on 3-dimensional imaging and is variable across individuals.