Use of Two-Piece Foot Orthoses to Adjust Lateral Inclination Angle in Medial Knee Osteoarthritis Treatment

Abstract

ABSTRACT Introduction Individualization of lateral inclination of foot orthoses (FO) is necessary to optimize the reduction of knee adduction moment (KAM) in medial knee osteoarthritis patients. The trial-and-error (or iterative) method is generally used for this purpose. Two kinds of orthoses can be used: several one-piece lateral FO (each with a different inclination height) for each patient or a two-piece lateral FO, that is, FO plus several laterally wedged insoles with different heights. The aim of this study was to determine whether comfort and mechanical impact on the knee and ankle are similar with the use of one-piece versus two-piece lateral FO during gait. Material and Methods Gait analysis was performed on 17 patients affected by medial knee osteoarthritis (grade II–III). Discomfort, frontal plane kinematics, and kinetics of the ankle and knee joints were compared in three conditions: without orthosis, with lateral customized FO, and with a combination of lateral wedge insoles and customized FO without lateral inclination. Lateral inclination was customized according to the orthotist's experience. Results One- and two-piece lateral customized FO had the same effect on the knee loading (p > 0.05). However, both conditions with FO led to similar significant differences in knee adduction and ankle eversion moment compared with the without-orthosis condition (p < 0.05; effect size from 0.05 to 0.40). Conclusions These results will be valuable for orthotists who make customized orthoses (with arch support) to reduce KAM in patients with medial knee osteoarthritis. Manufacturing two-piece orthoses is practical and economical: the customized FO can be kept and the wedge insole repeatedly replaced until the patient's pain is relieved.