Biomechanical changes accompanying unilateral and bilateral use of laterally wedged insoles with medial arch supports in patients with medial knee osteoarthritis

BackgroundLaterally wedged insoles have controversial effect in treating medial compartment knee osteoarthritis. This study examined the effects of unilateral and bilateral use of insoles having medial arch supports and of different inclinations on the frontal plane external hip, knee, subtalar moments and pelvic alignment.MethodsKinetic and kinematic gait parameters were collected from 21 patients with primary medial knee osteoarthritis. The insoles' inclinations were 0, 6 and 11°, where each of the 6° and 11° was used once unilaterally and another bilaterally while the 0° was used bilaterally as a control.FindingsThe Multivariate Analysis of Variance revealed significant increase in the external subtalar eversion moment using either of the 6° or 11° laterally wedged vs the 0° non-wedged insole conditions (P = 0.003). Moreover, there were significant increases in the external eversion moment using the 11° vs the 6° insole conditions (P < 0.05). However, there were no significant differences for the remaining tested variables (P > 0.05). The bivariate correlations revealed significant negative correlations between the subtalar eversion and knee adduction moments (r = − 0.409, P = 0.000) and the subtalar eversion and hip adduction moments (r = − 0.226, P = 0.049), and positive correlation between the hip and knee adduction moments (r = 0.268, P = 0.019).InterpretationThe non-significant reduction in the external knee adduction moment may question the efficacy of using wedged insoles having medial arch supports in treating patients with medial knee osteoarthritis. Additionally, using such insoles did not produce appreciable mechanical effects on remote articulations as the hip and pelvis.