This study was conducted in order to assess the effect of wearing a lateral wedged insole with a subtalar strap for 2 years in patients with osteoarthritis varus deformity of the knee (knee OA).
The setting was an outpatient clinic. The efficacies of the strapped insole and a traditional shoe insert wedged insole (the inserted insole), as a positive control, were compared at the baseline and after 2 years of treatment. Randomization was performed according to birth date. The 61 female outpatients with knee OA who completed a prior 6-month study were asked to wear their respective insoles continuously as treatment during the course of the 2-year study. The femorotibial angle (FTA) was assessed by standing radiographs obtained while the subjects were barefoot and the Lequesne index of the knee OA at 2 years was compared with those at baseline in each insole group.
There were 61 patients in the original study, but 13 patients (21.3%) did not want to wear the insole continuously and five (8.2%) withdrew for other reasons. The 42 patients who completed the 2-year study were evaluated. At the 2-year assessment, participants wearing the subtalar strapped insole (n=21) demonstrated significantly decreased FTA (P=0.015), and significantly improved Lequesne index (P=0.031) in comparison with their baseline assessments. These significant differences were not found in the group with the traditional shoe inserted wedged insole (n=21).
Only those participants using the subtalar strapped insole demonstrated significant change in the FTA in comparison with the baseline assessments. If the insole with a subtalar strap maintains FTA for more than 2 years, it may restrict the progression of degenerative articular cartilage lesions of knee OA.