Systematic Review
Efficacy of Intra-articular Platelet-Rich Plasma Injections in Knee Osteoarthritis: A Systematic Review

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Purpose

To determine (1) whether platelet-rich plasma (PRP) injection significantly improves validated patient-reported outcomes in patients with symptomatic knee osteoarthritis (OA) at 6 and 12 months postinjection, (2) differences in outcomes between PRP and corticosteroid injections or viscosupplementation or placebo injections at 6 and 12 months postinjection, and (3) similarities and differences in outcomes based on the PRP formulations used in the analyzed studies.

Methods

PubMed, Cochrane Central Register of Controlled Trials, SCOPUS, and Sport Discus were searched for English-language, level I evidence, human in vivo studies on the treatment of symptomatic knee OA with intra-articular PRP compared with other options, with a minimum of 6 months of follow-up. A quality assessment of all articles was performed using the Modified Coleman Methodology Score (average, 83.3/100), and outcomes were analyzed using 2-proportion z-tests.

Results

Six articles (739 patients, 817 knees, 39% males, mean age of 59.9 years, with 38 weeks average follow-up) were analyzed. All studies met minimal clinical important difference criteria and showed significant improvements in statistical and clinical outcomes, including pain, physical function, and stiffness, with PRP. All but one study showed significant differences in clinical outcomes between PRP and hyaluronic acid (HA) or PRP and placebo in pain and function. Average pretreatment Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were 52.36 and 52.05 for the PRP and HA groups, respectively (P = .420). Mean post-treatment WOMAC scores for PRP were significantly better than for HA at 3 to 6 months (28.5 and 43.4, respectively; P = .0008) and at 6 to 12 months (22.8 and 38.1, respectively; P = .0062). None of the included studies used corticosteroids.

Conclusions

In patients with symptomatic knee OA, PRP injection results in significant clinical improvements up to 12 months postinjection. Clinical outcomes and WOMAC scores are significantly better after PRP versus HA at 3 to 12 months postinjection. There is limited evidence for comparing leukocyte-rich versus leukocyte-poor PRP or PRP versus steroids in this study.

Level of Evidence

Level I, systematic review of Level I studies.

Section snippets

Methods

A systematic review was registered on PROSPERO on August 12, 2014 (registration ID: CRD42014013032). Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed.17 English-language original research therapeutic level I evidence (based on Oxford Centre for Evidence Based Medicine) randomized comparative trials were eligible for inclusion.18 The studies that were sought compared the use of autologous PRP with HA viscosupplementation, corticosteroid, placebo, or

Results

Six articles (739 patients, 817 knees) were analyzed (Table 2). There were 39% males and 61% females with a mean age of 59.9 years per patient and 59.2 years per knee and mean follow-up of 38 weeks per patient and 37 weeks per knee. Radiographically, the Kellgren-Lawrence and Ahlback grading systems were used determine severity of knee OA. Two studies used the Ahlback classification system and showed that 58.2% were grade I, 32.4% were grade II, and 9.4% were grade III. Four studies used the

Discussion

It was determined that intra-articular PRP injections significantly improve the clinical outcomes in symptomatic knee OA. PRP was also shown to be significantly better than HA or placebo for the treatment of symptomatic knee OA. Treating OA nonoperatively has been ongoing for several decades. Multiple studies have reported the use of HA, PRP, and corticosteroids, among other agents, in the nonoperative treatment of OA. While there are a good amount of studies documenting the use of HA in the

Conclusions

In patients with symptomatic knee OA, PRP injection results in significant clinical improvements up to 12 months postinjection. Clinical outcomes and WOMAC scores are significantly better after leukocyte-poor PRP versus HA at 3 to 12 months postinjection. There is limited evidence for comparing leukocyte-rich versus leukocyte-poor PRP in this study.

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    See commentary on page 506

    The authors report the following potential conflicts of interest or sources of funding: P.C.M. is on the Speaker's Bureau/Paid Presentation of Genzyme; receives research support from DePuy, a Johnson & Johnson Company, Arthrex, and Zimmer; and is on the editorial/governing board of the Journal of Knee Surgery and Orthobullets.com. K.E.V. receives IP royalties from Solana and is a paid consultant for Solana, Stock, and Wright Medical. J.D.H. is on the editorial board of Arthroscopy, the Journal of Arthroscopic and Related Surgery, and Frontiers in Surgery and receives publication royalties from SLACK.

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