Relationship between hip abductor strength and external hip and knee adduction moments in medial knee osteoarthritis

Abstract Background Alterations in hip abductor strength and hip and knee adduction moments during gait are associated with knee osteoarthritis. This study examines the relationship between hip abductor strength and hip and knee adduction moments during gait in individuals with symptomatic medial knee osteoarthritis. Methods Ninety-nine participants underwent maximal isometric hip abductor strength testing and 3D gait analysis. Pearson correlations examined relationships between non-normalized maximal hip abductor strength (Nm), peak external hip and knee adduction moments (Nm) and knee adduction moment impulse (Nm·s). Linear regressions examined these relationships while controlling for body size (height and mass) and walking speed. Findings Positive relationships existed between non-normalized hip abductor strength and hip and knee adduction moments (r = 0.28 and 0.37, respectively, p < 0.01) as well as the knee adduction moment impulse (r = 0.47, p < 0.01). However, after controlling for body size and walking speed, hip abductor strength was not a significant predictor of hip or knee adduction moments (B = - 0.08, and 0.04, respectively, p > 0.05) but was a significant predictor of knee adduction moment impulse (B = 0.05, p = 0.005), explaining 6% of the variance. Interpretation While a significant relationship between hip abductor strength and knee adduction moment impulse was noted, hip abductor strength only explained a small amount of variance in the impulse. Our findings support previous research of healthy individuals and those with mild to moderate knee osteoarthritis and suggests hip abductor strength has little influence on hip and knee adduction moments during gait.