Does decreasing the foot progression angle (toe-in gait) reduce medial contact loads in the knee?

Medial compartment osteoarthritis is a leading cause of years claimed by disability worldwide. Joint replacements improve the quality of life for individuals with end-stage osteoarthritis; however, less invasive interventions to prevent or delay surgery are desirable. Increased contact forces in the medial compartment of the knee joint are thought to accelerate the progression of osteoarthritis.

Knee adduction moment (KAM) and total tibiofemoral force (TF) are potential correlates to medial contact force (MCF) in the knee joint (Kutzner et al., 2013; Nagura et al., 2006). Shull et al. (2012) showed experimentally that shifting the foot progression angle inward during walking (i.e. toe-in gait) could reduce the first peak in KAM during stance. This is accomplished by shifting foot's center of pressure laterally and altering the ground reaction force vector. Lowering the KAM tends to shift knee contact forces laterally, thus potentially alleviating load on the medial compartment. DeMers et al. (2014) showed that muscle recruitment optimization could be leveraged to lower the second peak of TF. His study reveals the sensitivity of contact forces in the knee to internal muscle forces, particularly for muscles crossing the knee joint. Winby et al. (2009) further describes that medial contact force is 42% external forces contribution (i..e ground reaction forces) and 58% internal contributes (i.e. muscle activation). Decreasing MCF is the focus of interventions to decelerate progression of medial compartment osteoarthritis.

By building a lower-body musculoskeletal model that combines Rajagopal’s full-body musculoskeletal model and Lerner’s contact model of the knee joint, we will confirm whether toe-in gait reduces medial contact force in the knee (Rajagopal et al., 2012; Lerner et al., 2015).