Is the Wedged Insole an Effective Treatment Option When Compared with a Flat (Placebo) Insole: A Systematic Review and Meta-Analysis

BACKGROUND: Using the lateral wedge insole is a conservative management strategy for knee osteoarthritis. The theoretical basis for this intervention is to correct femorotibial angle, thereby reducing pain and optimising function. OBJECTIVE: This systematic review evaluates the evidence on the effectiveness of wedge insole compared with flat insole for the treatment of knee osteoarthritis. METHODS: A systematic review was performed, searching published (MEDLINE, EMBASE, CNKI, Cochrane Library, and Web of Science) and unpublished literature from their inception to April 2018. Randomized controlled trials (RCTs) that compared the use of wedge insole with a flat insole were included. Risk of bias and clinical relevance were assessed, and outcomes were analysed through meta-analysis. RESULT: From a total of 413 citations, 8 studies adhered to the a priori eligibility criteria. The WOMAC pain was shown to be statistically nonsignificant change with the use of wedge insole (SMD=0.07), and low heterogeneity (I(2)=22%) and a 95% CI that crossed zero (95% CI: −0.09 to 0.24). The 5 independent trials were not significant in improving pain score (SMD = −0.02, 95% CI: −0.19 to 0.16). This review also revealed no significance in improving Lequesne index (SMD = −0.27, 95% CI: −0.72 to 0.19). The meta-analysis from the 2 independent trials was significant in improving femorotibial angle (SMD = −0.41, 95% CI: −0.73 to -0.09). In conclusion, this meta-analysis suggested that lateral wedge insoles can improve femorotibial angle but are of no benefit with pain and functions in knee osteoarthritis.