Knee loading in OA subjects is correlated to flexion and adduction moments and to contact point locations

This study evaluated the association of contact point locations with the knee medial and lateral contact force (F(med), F(lat)) alterations in OA and healthy subjects. A musculoskeletal model of the lower limb with subject-specific tibiofemoral contact point trajectories was used to estimate the F(med) and F(lat) in ten healthy and twelve OA subjects during treadmill gait. Regression analyses were performed to evaluate the correlation of the contact point locations, knee adduction moment (KAM), knee flexion moment (KFM), frontal plane alignment, and gait speed with the F(med) and F(lat). Medial contact point locations in the medial–lateral direction showed a poor correlation with the F(med) in OA (R(2) = 0.13, p = 0.01) and healthy (R(2) = 0.24, p = 0.001) subjects. Anterior–posterior location of the contact points also showed a poor correlation with the F(med) of OA subjects (R(2) = 0.32, p < 0.001). Across all subjects, KAM and KFM remained the best predictors of the F(med) and F(lat), respectively (R(2) between 0.62 and 0.69). Results suggest different mechanisms of contact force distribution in OA joints. The variations in the location of the contact points participate partially to explains the F(med) variations in OA subjects together with the KFM and KAM.