Effectiveness of Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: A Meta-analysis of Randomized Controlled Clinical Trials

Background: The effectiveness of platelet-rich plasma (PRP) injections for knee osteoarthritis and the effects of leukocyte-poor PRP (LP-PRP) versus leukocyte-rich PRP (LR-PRP) are still controversial. Purpose: To assess the effectiveness of different PRP injections through a direct and indirect meta-analysis of randomized controlled trials. Study Design: Systematic review; Level of evidence, 1. Methods: A systematic literature search of electronic databases (PubMed, Cochrane Library, and EMBASE) was performed to locate randomized controlled trials published through March 2019 that compared PRP with control treatment. A random-effects meta-analysis was conducted to synthesize the evidence, and meta-regression analyses were conducted to determine the influence of trial characteristics. An indirect comparison was performed to assess the effects of LP-PRP and LR-PRP compared with hyaluronic acid (HA). Results: A total of 21 trials were included. A clinically important benefit for pain relief was seen for intra-articular PRP compared with intra-articular saline (standardized mean difference [SMD] = -1.38 [95% CI, -2.07 to -0.70]; P < .0001; I (2) = 37%) and corticosteroid solution injection (SMD = -2.47 [95% CI, -3.34 to -1.61]; P < .00001; I (2) = 47%). As a result of heterogeneity (I (2) = 89%), there was no conclusive effect compared with HA, even though the pooling effect provided clinically relevant pain relief (SMD = -0.59 [95% CI, -0.97 to -0.21]; P = .003). Indirect meta-analysis showed that there was no significant difference between LR-PRP and LP-PRP. Conclusion: PRP injections are beneficial for pain relief and functional improvement in knee osteoarthritis. Larger, randomized high-quality studies are needed to compare the effects of LP-PRP and LR-PRP.

Automated summary

The study found that intra-articular PRP injections have clinically significant benefits for pain relief compared to saline solution or corticosteroid injection, but its efficacy compared to hyaluronic acid is inconclusive. Additionally, there was no significant difference between leukocyte-rich PRP and leukocyte-poor PRP in terms of treatment effects. Further larger and high-quality randomized studies are needed to further evaluate the effects of different PRP injections.