Sensitivity of musculoskeletal models to planar simplification of tibiofemoral motion

Planar tibiofemoral motion is commonly used for calculating muscle and joint forces in cohort-based and subject-specific studies [1]. However, this simplification may cause physiologically inadmissible ligament length and tibiofemoral motion, affecting calculation of muscle and joint forces. We compared musculoskeletal model outputs using a common planar simplification of tibiofemoral motion and a natural (spatial) tibiofemoral motion, consistent with the articular surface and ligament geometry, in a cohort of 13 healthy women.