Interaction of hip and foot factors associated with anterior knee pain in mountain bikers

Abstract

ObjectiveTo investigate the association of interactions among trunk, hip, and foot/ankle musculoskeletal factors with the presence of anterior knee pain (AKP) in mountain bikers. DesignCross-sectional study. SettingPrivate clinical setting. ParticipantsFifty professional and amateur cyclists, with and without AKP, were included. Main outcome measuresBridge test with unilateral knee extension, hip stability isometric test (HipSIT), passive hip internal rotation (IR) range of motion (ROM), shank-forefoot alignment (SFA), and ankle dorsiflexion ROM were analyzed by classification and regression tree (CART) to identify interactions with AKP presence. A receiver-operating characteristic (ROC) curve verified accuracy of the model. To investigate strength of associations, prevalence ratios were calculated for each terminal node of the CART model. ResultsInteractions among passive hip IR ROM, HipSIT, ankle dorsiflexion ROM and SFA identified mountain bikers with and without AKP. The model achieved 76.9% sensitivity and 87.5% specificity. The area under the ROC curve was 0.86 (95% confidence interval: 0.75–0.97; standard error 0.05; p < 0.0001). ConclusionPresence of AKP in mountain bike cyclists was associated with interactions among passive hip IR ROM, HipSIT and ankle dorsiflexion ROM captured by CART, indicating that the contribution of one factor depends on the presence of other factors.