The effect of a lateral wedge insole and a subtalar strap on gait parameters in knee osteoarthritis

Background: Lateral wedge insole (LWI) aims to reduce loading on medial compartment of tibiofemoral joint in mild knee osteoarthritis (KOA). This effect may be augmented by concomitant use of subtalar strap to fix the ankle joint. Moreover, longitudinal arch support embedded in insoles can cause foot comfort and may be beneficial for people with KOA. Therefore, this study aimed to assess the immediate effect of LWI with an arch support with and without a subtalar strap on the kinetics and kinematics of walking in mild KOA. Methods: A convenient sample of 17 individuals with mild KOA (Kellgren and Lawrence grade II), aged ≥ 40 years were assessed in 3 conditions: without the insole; LWI; and LWI with a subtalar strap, where an arch support was embedded in all insoles. The primary outcomes were external knee adduction moment and angular impulse. The secondary outcomes were hip flexion and adduction moments, knee flexion angle, ankle eversion moment, and walking speed. The repeated measurements ANOVA was used to compare the primary and secondary outcomes between the conditions using SPSS. Significance level was set at 0.05. Results: LWI and a subtalar strap can significantly increase the knee flexion angle at 0%-15% of the stance phase compared to no insole (p<0.001). No other changes were observed (p=0.142). Conclusion: LWI with an arch, with or without a subtalar strap, cannot impose any immediate changes on the kinetics and kinematics of lower limb joints during walking in people with mild KOA.