The lateral wedged insole with subtalar strapping significantly reduces dynamic knee load in the medial compartment: Gait analysis on patients with medial knee osteoarthritis

Abstract

Two lateral wedged insoles were compared: one with, and the other without, subtalar strapping. Twenty-one patients (age 58-83, mean 72) with medial knee osteoarthritis (OA) were enrolled. Thirty-seven knees in the patients were divided into three groups based on the Kellgren and Lawrence OA grading system; grades 2 (cases=20), 3 (cases=11), and 4 (cases=6). The subjects were tested during walking barefoot and during walking with a silicon rubber lateral wedged insole with elevation of 10 mm attached to a barefoot. Gait analysis was performed on a 10 m walkway for each subject under three different walking conditions; barefoot, wearing a conventional insole, and a subtalar strapping insole. Peak knee varus moment during gait was measured under each condition, and compared between the three conditions and between the OA grades. On the whole (cases=37), the peak varus moment was significantly reduced by wearing either of the insoles, compared to walking barefoot. The reduction was more obvious with the strapping insole (-13%, P<0.01), compared with the conventional insole (-8%, P<0.05). In moderate OA patients (grades 2 and 3), the moments were significantly lower with the strapping insole, compared with the conventional insole (P=0.0048 and 0.005, respectively). However, no significant difference was detected in severe OA patients (grade 4) between the two types of insoles (P=0.4). Both lateral wedged insoles significantly reduced the peak medial compartment load during gait. The subtalar strapping insole had a greater effect than the conventional insole, particularly in patients with moderate medial knee OA.