Knee osteoarthritis (OA), is the most common degenerative joint disease. Several non-pharmacological interventions have been used for this purpose such as insoles. There are contradictory data about the superiority and effectiveness of laterally wedged compared with neutrally wedged insoles. This study was designed to compare the effectiveness of laterally and neutrally wedged insoles in management of knee OA.
In this double-blind, parallel treatment trial, 118 patients with knee OA according to American College of Rheumatology (ACR) criteria were enrolled and were followed for 2 months. Patients were randomly divided into two groups. Fifty-seven of them were treated with 5° laterally elevated wedged insoles (group A) and 61 patients were treated with neutrally wedged insoles (group B). Edinburg Knee Functional Scale (EKFS) was used to evaluate knee function before and after interventions. At the end of 2 months, severity of knee pain during the previous 2 days, numbers of non-steroid anti inflammatory drugs (NSAIDs) used for pain relief within the last 2 weeks and EKFS were assessed.
Severity of knee pain decreased in both groups after intervention. The mean difference in groups A (laterally wedged insole) and B (neutrally wedged insole) were 29.3 (95% confidence interval [95% CI]: 25.12, 33.55) and 6.25 (95% CI: 3.09, 9.4), respectively (P < 0.001 for both). In addition, at the end of the study, EKFS improved significantly in group A (mean: 7.54, 95% CI: 6.3, 8.8; P < 0.001), while in group B we could not find significant improvement (mean: 0.54, 95% CI: -0.41, 1.5; P = 0.166). Numbers of NSAIDs used during the two final weeks of the study significantly decreased compared with baseline in group A (P = 0.001; mean: 2.6, 95% CI: 1.3, 3.9); while in group B this was not shown (P = 0.9; mean: 0.05, 95% CI:-0.87, 0.97).
This study suggests that laterally elevated wedged insoles are more effective than neutrally wedged insoles, in pain relief of knee OA.