What people ask about PRP

Sources

1. In the RESTORE trial - the largest placebo-controlled PRP trial in knee osteoarthritis - 288 adults aged 50+ with symptomatic Kellgren-Lawrence grade 2-3 medial knee OA received three weekly intra-articular injections of leukocyte-poor PRP from a commercial system or saline placebo. At 12 months the mean change in knee pain was -2.1 points with PRP versus -1.8 with saline (difference -0.4; 95% CI -0.9 to 0.2; P=.17) against a minimum clinically important difference of 1.8, and the change in medial tibial cartilage volume was -1.4% versus -1.2% (difference -0.2%; 95% CI -1.9% to 1.5%; P=.81). Twenty-nine of 31 prespecified secondary outcomes showed no significant between-group difference. The authors concluded the findings do not support use of PRP for knee OA.

   Bennell KL, Paterson KL, Metcalf BR, et al. — Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial. JAMA, 2021. DOI: 10.1001/jama.2021.19415.

2. A meta-analysis of 73 articles covering 5,895 patients quantified the PLACEBO response to intra-articular injection in knee osteoarthritis: statistically and clinically significant improvements in pain, function and quality of life at 1, 3 and 6 months, with responder rates above 50% at each of those points, declining by 12 months. The placebo response was stronger in trials with more female participants and in more recently published trials. This is why an uncontrolled 'our patients improved' figure carries almost no information.

   Previtali D, Boffa A, Di Laura Frattura G, et al. — Placebo response to intra-articular injections in knee osteoarthritis: magnitude, evolution over time, and influencing factors. A systematic review and meta-analysis with meta-regression. EFORT Open Reviews, 2025. DOI: 10.1530/EOR-2025-0022.

3. A Bayesian network meta-analysis restricted to LARGE randomized trials (at least 100 patients per group; 57 trials, 22,795 participants, 18 intra-articular interventions) found treatment effects were larger in the 35 high-risk-of-bias trials than in the 22 low/unclear-risk trials. Excluding high-risk trials, the effects of 16 of the 18 intra-articular interventions in knee or hip OA were smaller than the minimal clinically important difference and most were consistent with placebo effects; triamcinolone had the highest probability of exceeding the MID at weeks 2-6.

   Pereira TV, Saadat P, Bobos P, et al. — Effectiveness and safety of intra-articular interventions for knee and hip osteoarthritis based on large randomized trials: A systematic review and network meta-analysis. Osteoarthritis and Cartilage, 2025. DOI: 10.1016/j.joca.2024.08.014.

4. The devices used to spin PRP at the point of care are cleared by FDA as clinical centrifuges, product code JQC, a Class I device under 21 CFR 862.2050 - for example the Biomet GPS Platelet Separation Kit (K030555, cleared 2003) and the Harvest SmartPrep2 / SmartPrep Platelet Concentration System (K103340, cleared 2010). That clearance covers the equipment that separates blood. It is not an FDA approval of platelet-rich plasma as a treatment for osteoarthritis, tendinopathy or any other orthopedic condition, and copy must never blur the two.

   U.S. Food and Drug Administration (Center for Devices and Radiological Health) — 510(k) Premarket Notification database and Product Classification: JQC, Centrifuges (Micro, Ultra, Refrigerated) For Clinical Use, 21 CFR 862.2050. FDA accessdata (CDRH device databases), 2003.

5. Medicare's national coverage policy covers autologous platelet-rich plasma ONLY for patients with chronic non-healing diabetic, pressure and/or venous wounds, and only within an approved coverage-with-evidence-development clinical study. There is no Medicare national coverage for PRP in osteoarthritis or tendinopathy, which is why these injections are billed to the patient as cash-pay.

   Centers for Medicare & Medicaid Services — Autologous Platelet-rich Plasma (Coverage with Evidence Development). CMS.gov, 2024.

6. A systematic review of 105 clinical PRP studies in orthopaedics published 2006-2016 found that only 11 (10%) described the preparation protocol clearly enough for another investigator to repeat it, and only 17 (16%) reported any quantitative metric of the final PRP composition. The authors concluded that the current reporting of PRP preparation and composition does not allow the PRP products actually delivered to patients to be compared between studies.

   Chahla J, Cinque ME, Piuzzi NS, et al. — A Call for Standardization in Platelet-Rich Plasma Preparation Protocols and Composition Reporting: A Systematic Review of the Clinical Orthopaedic Literature. Journal of Bone and Joint Surgery (American), 2017. DOI: 10.2106/JBJS.16.01374.

7. The ESSKA-ICRS consensus applied the RAND/UCLA appropriateness method to 216 clinical scenarios for intra-articular PRP in knee OA. Only 84 scenarios (38.9%) were rated appropriate, 9 (4.2%) inappropriate and 123 (56.9%) uncertain. PRP was judged appropriate in patients aged 80 or under with KL grade 0-III osteoarthritis AFTER failed conservative non-injective or injective treatment; it was NOT considered appropriate as a first treatment, nor in KL grade IV (bone-on-bone) osteoarthritis, where 91.7% and 87.5% of scenarios respectively were uncertain.

   Kon E, de Girolamo L, Laver L, et al. — Platelet-rich plasma injections for the management of knee osteoarthritis: The ESSKA-ICRS consensus. Recommendations using the RAND/UCLA appropriateness method for different clinical scenarios. Knee Surgery, Sports Traumatology, Arthroscopy, 2024. DOI: 10.1002/ksa.12320.

8. A study training predictive models on imaging features found that neither radiographic grading (IRF) nor MRI-based MOAKS scoring predicted patient pain or symptoms in knee osteoarthritis - the best model reached an R-squared of only 0.28, and predictive performance got WORSE as symptoms got more severe. An X-ray grade is not a prediction of how much someone hurts, and it is not on its own a reason to treat or not treat.

   Hill BG, Eble S, Moschetti WE, et al. — The Discordance Between Pain and Imaging in Knee Osteoarthritis. Journal of the American Academy of Orthopaedic Surgeons, 2025. DOI: 10.5435/JAAOS-D-24-00509.

9. The Cochrane review of STEM CELL injections for knee osteoarthritis concluded that on low-certainty evidence they may slightly improve pain and function, with uncertainty about effects on quality of life, treatment success and structural progression, and uncertainty about safety. This matters on a PRP site because 'stem cell therapy' is routinely used as a marketing label for PRP; they are different products with different evidence and PRP must never be described as a stem cell treatment.

   Whittle SL, Johnston RV, McDonald S, et al. — Stem cell injections for osteoarthritis of the knee. Cochrane Database of Systematic Reviews, 2025. DOI: 10.1002/14651858.CD013342.pub2.