Lateral wedge insoles for reducing biomechanical risk factors for medial knee osteoarthritis progression : a systematic review and meta-analysis

Objective Lateral wedge insoles are intended to reduce biomechanical risk factors of medial knee osteoarthritis (OA) progression, such as increased knee joint load; however, there has been no definitive consensus on this topic. The aim of this systematic review and meta-analysis was to establish the within-subject effects of lateral wedge insoles on knee joint load in people with medial knee OA during walking. Methods Six databases were searched from inception until February 13th 2015. Included studies reported on the acute biomechanical effects of lateral wedge insoles in people with medial knee osteoarthritis during walking. Primary outcomes of interest relating to the biomechanical risk of disease progression were the 1st and 2nd peak external knee adduction moment (EKAM) and knee adduction angular impulse (KAAI). Eligible studies were pooled using random-effects meta-analysis. Results Eighteen studies were included with a total of 534 participants. Lateral wedge insoles resulted in a small but statistically significant reduction in the 1st peak EKAM (SMD: -0.19; 95% CI -0.23 − -0.15) and 2nd peak EKAM (SMD: -0.25; 95% CI -0.32 − -0.19) with a low level of heterogeneity (I2 = 5% and 30%, respectively). There was a favourable but small reduction in the KAAI with lateral wedge insoles (SMD: -0.14; 95% CI -0.21 − -0.07, I2 =31%). Risk of methodological bias scores (Quality Index) ranged from 8 to 13 out of 16. Conclusions Lateral wedge insoles cause small reductions in the EKAM and KAAI in people with medial knee OA during walking. At present, they appear ineffective at attenuating structural changes in people with medial knee OA as a whole and may be better suited to targeted use in biomechanical phenotypes associated with larger reductions in knee load