What to ask before trusting a prp injection success rate

What to ask about the blood mix and results

Clinics don't all prepare PRP the same way. Their mixtures can hold varying levels of platelets and white cells.

More of either kind isn't always better or safer. The useful mix can differ between a joint and tissue joining muscle to bone.

Concentrated PRP means the kept layer has more platelets than ordinary blood. Think of coffee made stronger by using more grounds.

Ask which blood cells remain in the mix. Then ask why that mix suits your exam and sore body part.

A prp injection success rate needs plain details. Ask which joint was studied and what the report called success.

Also ask how long the relief lasted. One broad number can't tell you what will happen.

Less soreness doesn't mean replacing the joint or growing it back. Research hasn't shown PRP can rebuild worn knee cartilage.

Soreness and swelling can occur for a short time afterward. Ask what's expected and which changes mean a call is needed.

Don't trust a promise of certain relief. People can have different results from the same care.

Let the clinic know about aspirin, blood thinners, or bleeding trouble. You mustn't change those medicines on your own.

Ask when you can return to normal movement. Written care steps can help once you're home.

Keep the paper where you'll see it. It'll guide you if soreness changes during the first few days.

Sources

1. 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.

2. A prospective cohort of 253 patients with KL 1-3 knee OA treated with three injections of 5 mL of autologous PRP found that platelet concentration positively correlated with clinical outcome. KOOS Pain improved more with higher platelet concentration at 2 months (P=.036), 6 months (P=.009) and 12 months (P=.014), with the same trend across other KOOS subscales and IKDC. The failure rate was 15.0% in the low-platelet group versus 3.3% in both the medium- and high-platelet groups, with no difference in adverse events.

   Boffa A, De Marziani L, Andriolo L, et al. — Influence of Platelet Concentration on the Clinical Outcome of Platelet-Rich Plasma Injections in Knee Osteoarthritis. American Journal of Sports Medicine, 2024. DOI: 10.1177/03635465241283463.

3. 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.

4. 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.

5. 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.