BackgroundLateral wedge insoles are traditionally used to reduce the adduction moment that crosses the knee during walking in people with medial knee osteoarthritis. However, the best degree to reduce knee joint load is not yet well established.MethodsElectronic databases were searched from their inception until May 2017. Included studies reported on the immediate biomechanical effects of different degrees of lateral wedge insoles during walking in people with knee osteoarthritis. The main measures of interest relating to the biomechanics were the first and second peak of external knee adduction moment and knee adduction angular impulse. For the comparison of the biomechanical effects of different degrees of insoles, the studies were divided in three subgroups: insoles with a degree higher than 0° and equal to or lower than 5°; insoles higher than 5° and equal to or lower than 9°; and insoles higher than 9°. Eligible studies were pooled using random-effects meta-analysis.ResultsFifteen studies with a total of 415 participants met all eligibility criteria and were included in the final review and meta-analysis. The overall effect suggests that lateral wedge insoles resulted in a statistically significant reduction in the first peak (standardized mean difference [SMD] –0.25; 95% confidence interval [CI] –0.36, − 0.13; P < 0.001), second peak (SMD –0.26 [95% CI –0.48, − 0.04]; P = 0.02) and knee adduction angular impulse (SMD –0.17 [95% CI –0.31, − 0.03]; P = 0.02). The test of subgroups found no statistically significant differences.ConclusionSystematic review and meta-analysis suggests that lateral wedge insoles cause an overall slight reduction in the biomechanical parameters. Higher degrees do not show higher reductions than lower degrees. Prior analysis of biomechanical parameters may be a valid option for selecting the optimal angle of wedge that best fits in knee osteoarthritis patients with the lowest possible degree.

Background: Lateral wedge insoles adjusted by biomechanical analysis may improve the condition of patients with medial knee osteoarthritis. Design: This is a prospective, randomized, controlled, single-blind clinical trial. Setting: The study was conducted in a biomechanics laboratory. Subjects: A total of 38 patients with medial knee osteoarthritis were allocated to either an experimental group (lateral wedge insoles) or a control group (neutral insoles). Interventions: Experimental group ( n = 20) received an adjusted lateral wedge insole of 2, 4, 6, 8, or 10 degrees, after previous biomechanical analysis. Control group ( n = 18) received a neutral insole (0 degrees). All patients used the insoles for 12 weeks. Main measures: Visual analogue scale, Knee Injury and Osteoarthritis Outcome Score questionnaire, biomechanical parameters: first and second peak of the external knee adduction moment and knee adduction angular impulse, and physical performance tests: 30-second sit-to-stand test, the 40-m fast-paced walk test, and the 12-step stair-climb test. Results: After 12 weeks, between-group differences did not differ significantly for pain intensity (−12.5 mm, (95% CI −29.4–4.4)), biomechanical parameters ( p = 0.05), Knee Injury and Osteoarthritis Outcome Score, and physical performance tests, except on the Knee Injury and Osteoarthritis Outcome Score subscale other symptoms ( p = 0.002; 13.8 points, (95% CI 5.6–22.0)). Conclusion: Tailored wedge insoles were no more effective at improving biomechanical or clinically meaningful outcomes than neutral insoles, except on symptoms. More participants from the experimental group reported they felt some improvement. However, these effects were minimal and without clinical significance.

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Lateral wedge insoles are recommended in order to minimize the impacts of osteoarthritis of the knee. The amount of wedging required to induce a biomechanical response with clinical significance is still controversial. This study aimed to investigate the immediate biomechanical effects of different amounts of wedging in symptomatic medial knee OA. A 3D motion capture system and five force platforms were used to acquire walking kinematic and kinetic data along a 10 m walkway. Each participant was tested for six different lateral wedge insoles (0, 2, 4, 6, 8, and 10°) in a randomized order. Thirty-eight patients with medial osteoarthritis of the knee were recruited. The application of insoles resulted in an incremental reduction of the first peak of the external knee adduction moment under all experimental conditions in comparison with the control condition (0° insole). A significant increase (p < 0.05) was observed in peak ankle eversion and in ankle eversion at the first peak of the external knee adduction moment with insoles higher than 8° and 6°, respectively. Slight variations to lateral wedge insoles, greater than 2°, appear to induce significant biomechanical changes in patients with knee osteoarthritis.