The use of platelet-rich plasma (PRP) was found to be non-superior to comparative groups in the examination of structural knee changes when treating knee osteoarthritis (OA), according to study results published in Journal of Arthroplasty.

In this systematic review and meta-analysis, researchers searched databases (PubMed, Cochrane Library, and Embase) for studies up to December 1, 2021, that assessed structural knee changes and the efficacy of PRP administration vs comparative cohorts. Inclusion criteria included the following:

  • Level of Evidence I;
  • Kellgren-Lawrence (KL) grade of I to III;
  • Modified Coleman Methodology Score (MCMS) of at least 55;
  • Available Visual Analog Scale (VAS) and/or Western Ontario and McMaster Universities Osteoarthritis Index scores; and
  • Comparison to either corticosteroid (CS), hyaluronic acid (HA), normal saline (NS), and/or exercise therapy.

A subanalysis was conducted to assess structural changes after PRP administration; any study examining the structural integrity of cartilage and/or synovial tissue with ultrasonography, radiography, and/or magnetic resonance imaging (MRI) was analyzed separately.

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In the 11 studies comparing the efficacy of PRP to HA, 7 studies had “fair” methodology scores, while the remaining 4 studies had “good” scores. Pooled analysis from 7 studies of those receiving PRP vs HA among cohorts demonstrated significantly improved VAS scores (mean deviation [MD] -0.66; 95% CI, -1.43 to 0.11; P <.001) and significantly improved total WOMAC scores (MD -8.32; 95% CI, -13.03 to -3.61]; P <.001); however, the i2statistic for both scores suggest substantial heterogeneity among all studies. In the 6 studies comparing efficacy of PRP with CS, 5 studies had “fair” scores, and 1 study had a “good” score.

Pooled analysis showed significantly improved VAS scores (MD -1.29; 95% CI, -2.31 to -0.28; P <.001) and WOMAC scores (MD, -3.73; 95% CI, -4.92 to -2.54; P <.001) among PRP compared with CS, but also with substantial heterogeneity among all studies. In the 5 studies comparing efficacy of PRP, 4 studies had “good” methodology scores, while the remaining 1 study had a “fair” score. Pooled analysis from 3 studies demonstrated significantly improved VAS scores (MD -1.14; 95% CI, -2.49 to -0.20; P =.02) and WOMAC scores (MD -15.45; 95% CI, -25.23 to -5.66; P <.001) among PRP compared with NS cohorts, with substantial heterogeneity among these studies. The 3 studies comparing PRP to exercise therapy revealed “fair” methodology; pooled analysis of the studies did not demonstrate statistically significant VAS and WOMAC scores. In assessing knee structural changes at 6 months mean follow-up, researchers found that 2 reports showed superior findings among the PRP cohort (decreased synovial vascularity, hypertrophy, and effusion, as well as improvement of KL progression [P =.003]), but researchers found highly variable findings in the remaining reports that extended at least 12 months.

Limitations of the study included highly variable baseline characteristics (ie, ages of study participants and body mass indices), cohort sizes, and study durations. There was also a lack of a standardized protocol and ambiguous regulations concerning PRP. However, researchers suggested that the findings from this meta-analysis should serve as a catalyst for future high-level studies with improved methodologies, larger sample sizes, and longer study durations.

The study authors concluded, “The use of PRP compared [with] CS, HA, NS, and exercise therapy is favored in most studies, but their clinical relevance remains non-superior. Knee structural changes following PRP administration are also no different than comparative cohorts. These studies remain inconclusive for multiple reasons: varying levels of methodology scores; small samples sizes; and inconsistent study durations. Despite the rapid rise of PRP use in orthopaedic clinics, this review highlights its uncertain efficacy and changes to knee structure following administration.”


Sax OC, Chen Z, Mont MA, Delanois RE. The efficacy of platelet-rich plasma for the treatment of knee osteoarthritis symptoms and structural changes: a systematic review and meta-analysis. J Arth. 2022. Published online May 7, 2022. doi:10.1016/j.arth.2022.05.014