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Review
. 2021 Mar 2;9(3):2325967120973284.
doi: 10.1177/2325967120973284. eCollection 2021 Mar.

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

Liu-Yan Nie  1 , Kun Zhao  2 , Jiaqi Ruan  2 , Jing Xue  1
Affiliations
Review

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

Liu-Yan Nie et al. Orthop J Sports Med. .

Abstract

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.

Keywords: knee osteoarthritis; meta-analysis; platelet-rich plasma; randomized controlled clinical trials; treatment.

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Conflict of interest statement

The authors declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Figures

Figure 1.
Figure 1.
Flowchart of the study-selection process for the meta-analysis. RCT, randomized controlled trial.
Figure 2.
Figure 2.
Forest plots for effectiveness of platelet-rich plasma (PRP) compared with different control groups for pain relief. (A) Overall effect. (B) Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain overall effect.
Figure 3.
Figure 3.
Results of sensitivity analysis for (A) pain relief and (B) functional improvement.
Figure 4.
Figure 4.
Indirect comparison of the effect of LP-PRP versus LR-PRP. ES, effect size; HA, hyaluronic acid; LP, leukocyte-poor; LR, leukocyte-rich; PRP, platelet-rich plasma.
FIGURE A1.
FIGURE A1.
Risk of bias of included trials. According to the Cochrane Collaboration tool, each item was graded as low risk (+), high risk (-), or unclear risk (?). The included trials were then graded as low quality (L), high quality (H), or moderate quality (M) based on the criteria as described by Zhao et al.
Figure A2.
Figure A2.
Forest plot for effectiveness of platelet-rich plasma (PRP) compared with controls for functional improvement. IV, inverse variance.
See this image and copyright information in PMC

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