Biomechanics of Iliotibial Band Friction Syndrome in Runners

Abstract

We propose a biomechanical model to explain the pathogenesis of iliotibial band friction syndrome in dis tance runners. The model is based on a kinematic study of nine runners with iliotibial band friction syn drome, a cadaveric study of 11 normal knees, and a literature review. Friction (or impingement) occurs near footstrike, predominantly in the foot contact phase, between the posterior edge of the iliotibial band and the underlying lateral femoral epicondyle. The study subjects had an average knee flexion angle of 21.4° ± 4.3° at footstrike, with friction occurring at, or slightly below, the 30° of flexion traditionally described in the literature. In the cadavers we examined, there was substantial variation in the width of the iliotibial bands. This variation may affect individual predisposition to iliotibial band friction syndrome. Downhill running pre disposes the runner to iliotibial band friction syndrome because the knee flexion angle at footstrike is reduced. Sprinting and faster running on level ground are less likely to cause or aggravate iliotibial band friction syn drome because, at footstrike, the knee is flexed be yond the angles at which friction occurs.