Dynamic effect of an elastically strapped lateral wedged insole on the subtalar joint in convenient foot print analysis using facsimile paper

Abstract We previously reported that insoles with subtalar strapping lead to valgus realignment of the femorotibial angle during the static phase in patients with osteoarthritis of the knee (knee OA) with varus deformity. In a follow-up study, we assessed the effect of an insole with subtalar strapping during the dynamic phase of the gait. Twenty-eight female patients with unilateral medial compartment knee OA and thirty-eight age- and sex-matched control subjects were enrolled. Gait analysis was performed for each subject while barefoot, with the insole with subtalar strapping, and with the insole with talonavicular strapping. In the knee OA group, the average foot angle while barefoot (12.4 ± 2.3°) was significantly higher than that in the control group (10.6 ± 3.4°) (P = 0.018). In the knee OA group, the angle while barefoot was significantly reduced after wearing the insole with subtalar strapping (9.4 ± 2.3°) (P < 0.0001), but not with use of the insole with talonavicular strapping (11.1 ± 2.8°) (P = 0.12). There was no significant difference in the foot angle among the three conditions in the control group (P > 0.05). This result suggests that the insole with subtalar strapping contributes to an adaptive mechanism which reduces the adductive moment at the knee through decreasing both the femorotibial angle and the external rotation of the foot position during walking.