Lateral wedge insoles have ‘no association’ with pain reduction in patients with medial knee osteoarthritis, suggests new UK analysis.
The researchers conducted a meta-analysis of 12 studies involving 890 participants with medial knee osteoarthritis. Over 500 received a lateral wedge insole, with the angle of the insoles varying from 5° to 15°. Control groups were patients who received an appropriate placebo (i.e. a neutral or flat insole or shoe) or no treatment. The outcome measure in the study was self-reported pain after treatment using the 20-point Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain scale. Treatment duration varied from two weeks to two months.
The pooled standardised mean difference (SMD) suggested a favourable association with lateral wedges, compared with patients in the control group (SMD -0.47), but the researchers cautioned that ‘substantial’ heterogeneity was present. This effect size represented an effect of -2.12 points on the WOMAC pain scale and larger trials with a lower risk of bias suggested a null association. Among trials in which control group patients received a neutral insole (n = 7), lateral wedges showed no association (SMD -0.03) on WOMAC; this represented an effect of -0.12 points, and results showed ‘little’ heterogeneity.
What this means for GPs
The researchers concluded that lateral wedges had ‘no association with pain’, compared with controls and that they were ‘not efficacious for the treatment of knee pain in persons with medial knee osteoarthritis’.