The aims of the study were to clarify the evidence on the magnitude and duration of treatment effect of intra-articular corticosteroid injections for knee osteoarthritis compared with placebo, to evaluate a treatment effect by steroid type, and to describe the reported adverse effects.
Cochrane Controlled Trials Register, Medline, Embase, CINAHL, Scopus, and Web of Science databases were searched. The risk of systematic bias was assessed according to the Cochrane Collaboration's domain-based evaluation framework.
The final sample included eight randomized controlled studies with follow-ups from 1 to 26 wks. The risk of systematic bias was considered low in five and high in three studies. The pooled standardized mean difference was -0.58 (95% confidence interval = -0.88 to -0.27) and number needed to treat 5.1 (95% confidence interval = 10.0 to 3.7). The heterogeneity was considerable. The pooled effect size approached the level of statistical insignificance at 4 mos. The pooled risk ratio of adverse effects was insignificant 0.95 (95% confidence interval = 0.34 to 2.55).
The intra-articular corticosteroid had a mild to moderate effect on pain severity up to 3 mos after the injection-much longer than it had previously been reported. The effect may vary substantially in different patient groups and appropriate patient selection is important. The risk of adverse effects was low.