The aim of this study was to assess the efficacy of platelet-rich plasma (PRP) in pain and self-report function of patients with knee osteoarthritis on the basis of comparisons with hyaluronic acid or placebo.
Best-evidence synthesis of randomized controlled trials (RCTs) was conducted. Literature retrieval was limited to RCTs assessing the efficacy of PRP in knee osteoarthritis. Methodology evaluation and data extraction were based on Cochrane Collaboration guidelines. Meta-analyses were performed using mean difference or standardized mean difference as effect size.
Ten RCTs were included and analyzed. Meta-analysis showed significant superiority of PRP in outcome scores when compared with hyaluronic acid (standardized mean difference = -0.85, P = 0.004, I = 93%), but no statistical difference was found in well-designed double-blind trials (standardized mean difference = -0.09, P = 0.38, I = 0%). Pooled standardized mean difference of trials comparing PRP with placebo directly was -2.13 (95% confidence interval = -3.29 to -0.98), and that of indirect comparison was -0.22 (95% confidence interval = -0.45 to -0.01).
In relieving pain and improving self-report function, PRP showed no superiority over hyaluronic acid in well-designed double-blind trials, and beneficial effects of PRP in most trials probably resulted from insufficient blinding methods. However, PRP is still considered more effective than placebo on the basis of present evidence.