The optimal degree of lateral wedge insoles for reducing knee joint load: a systematic review and meta-analysis

Abstract

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.

Can Slight Variations to Lateral Wedge Insoles Induce Significant Biomechanical Changes in Patients with Knee Osteoarthritis?

“…This result is similar to a previous study, suggesting that any slight change under the foot induces adaptations in the upper segments [34]. Therefore, the use of slight angulations could be a curious field of investigation, as high angulations under the foot usually cause greater discomfort during use [13]. Furthermore, the use of small changes in the material used in the insoles apparently also has an influence on the biomechanical parameters [35].…”

“…The amount of wedging that is needed to induce a biomechanical response with clinical significance is an essential research question, given that the effects on the clinical condition are still controversial [5,[10][11][12]. Different amounts of lateral wedging have been suggested, such as 4, 5, 6, 10, or 11 • [13]. Previous studies have failed to demonstrate effectiveness in patients with osteoarthritis of the knee, despite the acute effects on the biomechanics of these types of insoles [14].…”

“…Another aspect that should be considered is the adaptation of patients to the use of insoles. Insoles with very high angulations are usually uncomfortable, especially angulations greater than 8 • [13]. On the other hand, very low angulations may not have any biomechanical effects.…”

Effects of tailored lateral wedge insoles on medial knee osteoarthritis based on biomechanical analysis: 12-week randomized controlled trial

“…The fact that a higher reduction in the first peak of external knee adduction moment is required may impair participants' adherence to daily use of the insoles, recognizing that insoles with angles greater than 8-degrees increase the discomfort, adverse effects of their use and do not have a greater biomechanical effect to that of insoles with lower angles. 32 Another possible limitation may be the inclusion criterion that allowed participants up to 80 years old. In our study, the average age of participants was around 60 years.…”

Intra-session reliability of different angles of lateral wedge insoles in the biomechanical parameters of the knee

“…Different amounts of lateral wedging have been proposed, such as 4 [5], 5 [4,6], 6 [7], 10 [4,8] or 11 degrees [9]. So far, it seems not possible to reach a consensus on the correct amount of wedging [10]. However, results from previous studies could encourage an individual fitting, based on the perception that some individuals do not respond to a certain amount of wedging [11][12][13].…”