Biomechanical predictors of patellofemoral and tibiofemoral joint loads during running: A cross-sectional study

Clinicians lack accurate means to estimate patellofemoral (PFJ) and tibiofemoral (TFJ) kinetics outside the lab. We sought to identify biomechanical gait predictors of PFJ and TFJ kinetics in male and female runners. We used an idealized approach with 3-D motion capture via factors that are readily measured using clinical tools, i.e. 2-D video and wearable devices. Participants (n = 106; 53 females, 53 males) ran on an instrumented treadmill while kinematics, kinetics and temporospatial data were sampled. PFJ and TFJ contact forces were estimated via a musculoskeletal model. De-biased LASSO and ordinary least squares regression identified biomechanical predictors of peak, loading rate and cumulative PFJ and TFJ contact forces. Peak vertical ground reaction force (vGRF), peak knee flexion, peak ankle dorsiflexion, stance length and foot strike angle (all p < 0.05) were predictors of PFJ forces, while peak knee flexion, peak vGRF, foot strike angle, peak ankle dorsiflexion and stance length (all p < 0.05) were predictors of TFJ forces. There was no significant difference in sex-specific predictors for any of the PFJ or the TFJ outcome measures. In summary, these findings support the use of 2-D video and wearable data to provide reasonable estimates PFJ and TFJ kinetics during running.