PRP injections for the treatment of knee osteoarthritis
the improvement is clinically significant and influenced by platelet concentration: a meta-analysis of randomized controlled trials
Additional information
Authors
Bensa A.,
Previtali D.,
Sangiorgio A.,
Boffa A.,
Salerno M.,
Filardo G.
Type
Journal Article
Year
2025
Language
English
Abstract
Background: Platelet-rich plasma (PRP) has emerged as a promising therapeutic intervention for knee osteoarthritis (OA), attracting substantial clinical and research attention. However, the clinical relevance of the treatment benefit remains controversial. Purpose: To evaluate the effectiveness of PRP compared with placebo in patients with knee OA in terms of minimal clinically important difference (MCID) and to investigate the possible influence of platelet concentration on the clinical outcome. Study Design: Meta-analysis. Level of evidence 1. Methods: The search was conducted on 5 databases (PubMed, Cochrane Library, Scopus, Embase, Web of Science) using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Inclusion criteria were randomized controlled trials comparing PRP and placebo injections to treat knee OA, written in the English language, with no time limitation. The effects were quantified at 1-, 3-, 6-, and 12-month follow-up points. Visual analog scale (VAS) for pain and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were used, with subanalyses based on platelet concentration performed using a 1,000,000 ± 20% platelets/µL cutoff. The MCID values (VAS, 1.37; WOMAC, 6.4) were used to interpret clinical improvement. The articles’ quality was assessed using the Revised Tool for Risk of Bias in Randomized Trials and the Grading of Recommendations Assessment, Development and Evaluation guidelines. Results: Among the 5499 articles retrieved, 18 randomized controlled trials (1995 patients) were included. PRP presented statistically superior improvements in VAS and WOMAC scores compared with placebo at all follow-up points, exceeding the MCID at 3- and 6-month follow-up points for VAS and at all follow-up points for WOMAC. The subanalysis based on platelet concentration showed that high-platelet PRP provided clinically significant pain relief with the improvement exceeding the MCID compared with placebo at 3-, 6-, and 12-month follow-up points. In contrast, low-platelet PRP failed to offer a clinically perceivable benefit in terms of VAS score. WOMAC results showed that both products provided a clinically significant improvement at 3 and 6 months of follow-up. This benefit was maintained up to the 12-month follow-up in the high-platelet group but not in the low-platelet group, where the improvement compared with placebo did not reach statistical significance. Conclusion: This meta-analysis showed that PRP offered clinically relevant functional improvement at 1-, 3-, 6-, and 12-month follow-up points and pain relief at 3- and 6-month follow-up points compared with placebo for the treatment of knee OA. Platelet concentration was found to influence treatment efficacy, with high-platelet PRP providing superior pain relief and more durable functional improvement compared with low-platelet PRP.
Keywords
Platelet-rich plasma, PRP, Knee, Osteoarthritis, OA, Placebo
Journal
The American Journal of Sports Medicine
Volume
53
Number ( Month )
3
Pages (or article number)
745-754
ISSN
0363-5465, 1552-3365
Diffusion
License
License undefined
Visibility
Public
