Chronic ankle instability affects the association between knee joint angle and loading: musculoskeletal simulation study.

The purpose of this study was to calculate and compare (1) knee loads, (2) muscle-specific contributions to knee loads, and (3) effects of knee flexion angle on knee loads and muscle-specific load contributions during a forward jump-landing task in people with and without chronic ankle instability (CAI). Eight CAI patients and seven healthy controls performed a forward jump-landing task. We collected 3D kinematics, ground reaction force, and muscle activation and used musculoskeletal modeling. The results showed that only healthy controls exhibited an association between knee flexion angle and knee compressive impulse ( r  = 0.854, p  = .014). The lack of association in CAI group may lead to knee instability and increase knee injury risk in people with CAI.