Association of Flat Feet with Knee Moments and Western Ontario and McMaster Universities Arthritis Index in Knee Osteoarthritis

Introduction: Flat feet are prevalent among individuals with medial compartment knee osteoarthritis (KOA), showing a correlation with elevated knee pain and cartilage degeneration. This study investigates the relationship between calcaneal eversion angle (CEA) and medial longitudinal arch angle (MLAA) with knee kinetics and pain. Materials and Methods: This analytical observational study included 30 volunteers with moderate KOA. The Vicon motion analysis system and two synchronized force plates were employed to capture level walking and the static standing position to measure CEA and MLAA. The study assessed the first and second peaks of the knee adduction moment, knee adduction moment impulse, peak knee flexion moment, and the peak knee flexion angle at heel strike (PKFA-HS). The Western Ontario and McMaster Universities arthritis index (WOMAC) pain and physical function were evaluated. Results: A significant positive correlation was found between CEA and the knee pain sub-score (Pearson correlation [PC]=0.446, P=0.011) and WOMAC total score (PC=0.363, P=0.049). Additionally, a significant negative correlation was observed between CEA and peak knee flexion moment/PKFA-HS (PC=-0.418, P=0.022, and PC=-0.479, P=0.001, respectively). The results also indicated a negative significant correlation between MLAA and WOMAC pain sub-score (PC=-0.389, P=0.034). Conclusion: Increased CEA and decreased MLAA are associated with elevated WOMAC pain sub-score and decreased PKFA-HS in individuals with moderate KOA. Addressing flat feet should be considered in KOA management to enhance pain relief and functional outcomes.