Platelet-rich plasma (PRP), a blood-based shot, has different results by body part

Knee research gives a mixed answer

A knee with arthritis may feel stiff after sitting. It'll sometimes ache on stairs, swell after use, or make walking harder. Some knee studies found that people had less soreness or moved better after PRP than after other joint care. A large study didn't find more help than saline, sterile salt water with no blood treatment in it. A study can't say beforehand who will improve.

Now for your day-to-day choices. Exercise and common medicines may still ease soreness. Some people use a cane. Others prefer a brace. Losing weight may help when that applies to you. Don't dismiss these choices because they aren't a procedure. Your exam and the care you've already tried help the clinic decide whether PRP is worth discussing.

Mixed results mean the answer isn't settled.

Ankle and Achilles studies haven't shown the same benefit

An ankle may hurt from wear, an old injury, or a new twist. The Achilles tendon can get sore after many days of hard walking or exercise. If you hear a pop and lose strength, get an exam soon. An ankle study found PRP no better than saline. Achilles studies also found no extra help when both groups did the same exercises.

QC Kinetix offers natural pain treatments, including concentrated PRP, which is the separated part of your blood with more clotting cells. Medical providers, the clinic staff who examine you and give care, place it near the sore area without surgery. Nobody can say it will help before your exam shows what is wrong. Ask what finding supports the treatment. Ask what finding would rule it out.

Both answers matter.

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 18 Level I randomized trials (811 patients receiving PRP, 797 receiving hyaluronic acid, mean follow-up 11.1 months) found mean improvement in total WOMAC scores was significantly higher with PRP (44.7%) than with hyaluronic acid (12.6%) (P<.01), and 6 of 11 VAS-reporting studies found significantly less pain with PRP at latest follow-up.

   Belk JW, Kraeutler MJ, Houck DA, et al. — Platelet-Rich Plasma Versus Hyaluronic Acid for Knee Osteoarthritis: A Systematic Review and Meta-analysis of Randomized Controlled Trials. American Journal of Sports Medicine, 2021. DOI: 10.1177/0363546520909397.

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. A multicentre, double-blinded, placebo-controlled trial randomised 100 patients with ankle (tibiotalar) osteoarthritis to two ultrasound-guided intra-articular injections of PRP or placebo. Symptom scores improved by 10 points with PRP and 11 points with placebo, an adjusted between-group difference over 26 weeks of -1 (95% CI -6 to 3; P=.56). The authors concluded the results do not support the use of PRP injections for ankle osteoarthritis.

   Paget LDA, Reurink G, de Vos RJ, et al. — Effect of Platelet-Rich Plasma Injections vs Placebo on Ankle Symptoms and Function in Patients With Ankle Osteoarthritis: A Randomized Clinical Trial. JAMA, 2021. DOI: 10.1001/jama.2021.16602.

5. In a double-blind, placebo-controlled trial of 54 patients with chronic midportion Achilles tendinopathy, all doing eccentric exercises, VISA-A scores improved 21.7 points with PRP and 20.5 points with saline over 24 weeks - an adjusted between-group difference of -0.9 (95% CI -12.4 to 10.6), excluding the predefined relevant difference of 12 points. PRP added nothing to eccentric loading.

   de Vos RJ, Weir A, van Schie HT, et al. — Platelet-rich plasma injection for chronic Achilles tendinopathy: a randomized controlled trial. JAMA, 2010. DOI: 10.1001/jama.2009.1986.

6. A Bayesian network meta-analysis of nine studies (six RCTs, 1055 patients) found leukocyte-POOR PRP produced significantly better WOMAC scores than hyaluronic acid (mean difference -21.14; 95% CI -39.63 to -2.65) and than placebo (-17.84; 95% CI -34.95 to -0.73), while leukocyte-RICH PRP showed no such significant difference versus placebo. PRP of either type caused more local adverse reactions than hyaluronic acid (OR 5.63; 95% CI 1.38-22.90), almost always local swelling and pain, with no difference in safety between the two PRP types.

   Riboh JC, Saltzman BM, Yanke AB, et al. — Effect of Leukocyte Concentration on the Efficacy of Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis. American Journal of Sports Medicine, 2016. DOI: 10.1177/0363546515580787.

7. 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.