Medializing the Center of Pressure to Offload the Knee and Decelerate Osteoarthritis: Fact or Fiction

Gait modification, a well-accepted non-surgical strategy for management of knee osteoarthritis, attempts to decelerate osteoarthritis progression by offloading the knee joint. To achieve this, modified gait patterns which reduce the knee adduction moment (KAM), a validated surrogate of load distribution across medial and lateral knee compartment, are frequently attempted. Medializing foot center of pressure (COP) is one example of gait modification which attempts to reduce KAM by altering the location of the COP under the foot during stance. This gait strategy rapidly triggered technological investments to implement it, ranging from flexible shoes to auditory feedback training. However, recent evidence has found that although KAM is higher in patients with knee OA, KAM reduction does not necessarily guarantee a reduction in knee compressive loads and hence may not decelerate cartilage degeneration. Consequently, medializing the COP may reduce KAM but whether it effectively reduce tissue stress at tibial cartilage warrants further research. Additionally, it is not clear whether the strong association between KAM and COP displacement, reported during a laboratorybased level walking, remain as such during various daily-life activities outside of the lab and within the community. Collectively, these factors cast doubt on the effectiveness of medializing COP to decelerate disease progression. Taking advantage of in-shoe pressure insoles, we aimed to investigate the association between COP and stress distribution within the proximal tibial cartilage for a variety of different daily-life activities within a community setting