# Why do results differ for PRP made from your blood? *Why PRP Results Differ | PRP Injections Mesa* > Does PRP work? See why study results vary and what PRP injection success rate claims mean for PRP injections Mesa readers. Research gives mixed answers about PRP, and this page explains why in plain everyday words. PRP is prepared by spinning your blood and keeping the part rich in platelets. Studies have tested different sore areas and different ways of making that treatment before judging the results. ## Does PRP work? Some studies found less soreness or easier movement over time for certain knee and tendon problems. Other studies found little difference between PRP and a saltwater shot used for comparison in the same sore area. The research clearly shows that the tested treatments were not all made alike. It suggests some people may improve, but it cannot tell whether your joint will improve. ## What does a PRP injection success rate tell me? A success rate isn’t helpful until you know what counted as success in that report. Less soreness, easier walking, and avoiding surgery are different results. A clinic’s success rate also leaves out what might have happened with home care alone. Ask what result was counted and how long after treatment the clinic judged it. ## What is known, and what is still uncertain? The studies show that results differ by body area and by how the blood was spun. They suggest that any change may take time rather than appear at once. What remains unknown is whether the treatment will help one particular joint. Your exam and past care give a doctor more useful facts than a clinic percentage. Take any old scan and a note about care you have tried. Ask which result is most likely for your sore area. A careful answer will include what is still unknown. ## 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](https://pubmed.ncbi.nlm.nih.gov/29040132/). *Journal of Bone and Joint Surgery (American)*, 2017. DOI: 10.2106/JBJS.16.01374. 2. 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](https://pubmed.ncbi.nlm.nih.gov/34812863/). *JAMA*, 2021. DOI: 10.1001/jama.2021.19415. 3. A systematic review of 29 randomized trials of PRP for knee OA that reported a platelet count, concentration or dose found that the 28 treatment arms with statistically significant positive outcomes at 6 months had a mean platelet dose of 5,500 (+/-474) x 10^6, while the three arms without a positive difference averaged 2,302 (+/-437) x 10^6 (P<.01). The same separation held at 12 months: 5,464 versus 2,253 x 10^6 (P<.05). Berrigan WA, Bailowitz Z, Park A, et al. — [A Greater Platelet Dose May Yield Better Clinical Outcomes for Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: A Systematic Review](https://pubmed.ncbi.nlm.nih.gov/38513880/). *Arthroscopy*, 2025. DOI: 10.1016/j.arthro.2024.03.018. 4. 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](https://pubmed.ncbi.nlm.nih.gov/41031623/). *EFORT Open Reviews*, 2025. DOI: 10.1530/EOR-2025-0022. 5. 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](https://pubmed.ncbi.nlm.nih.gov/38961773/). *Knee Surgery, Sports Traumatology, Arthroscopy*, 2024. DOI: 10.1002/ksa.12320. 6. A systematic review that screened 876 studies and extracted standardised data from 33 commercially available PRP systems and protocols found that final product concentrations of platelets, white cells and growth factors varied widely between systems, as did the preparation protocols themselves. Platelet concentration correlated directly with the volume of blood drawn and with the centrifugal force of the device. The authors called the heterogeneity between separation systems something that 'must be resolved for proper study of this promising treatment'. Fadadu PP, Mazzola AJ, Hunter CW, et al. — [Review of concentration yields in commercially available platelet-rich plasma (PRP) systems: a call for PRP standardization](https://pubmed.ncbi.nlm.nih.gov/30992411/). *Regional Anesthesia and Pain Medicine*, 2019. DOI: 10.1136/rapm-2018-100356. 7. A meta-analysis of 15 studies in plantar fasciitis found PRP superior to corticosteroid on AOFAS at 6 and 12 months (P=.009 both) and on VAS at 3, 6 and 12 months, with no advantage in the first month. The authors added the caveat that nine of the fifteen studies had a high risk of bias and that 'different protocols for PRP preparation reduce the internal and external validity of these findings' - the preparation problem stated as an explicit limit on the conclusion. Hohmann E, Tetsworth K, Glatt V — [Platelet-Rich Plasma Versus Corticosteroids for the Treatment of Plantar Fasciitis: A Systematic Review and Meta-analysis](https://pubmed.ncbi.nlm.nih.gov/32822236/). *American Journal of Sports Medicine*, 2021. DOI: 10.1177/0363546520937293. 8. 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](https://pubmed.ncbi.nlm.nih.gov/25925602/). *American Journal of Sports Medicine*, 2016. DOI: 10.1177/0363546515580787. ## What if the soreness doesn't settle? At QC Kinetix, medical providers are licensed people responsible for your exam and treatment. They offer regenerative treatments made from your blood and prepared at the clinic. One choice is PRP: staff spin your blood and keep the part rich in platelets. After an exam, the provider can discuss whether that choice fits your soreness. Book a free consultation: --- Plain answers for a sore joint. Find reasons a joint aches, simple steps, urgent symptoms, blood-based PRP, price questions, and the two nearby offices. Clear information about sore joints, PRP choices, and care near Mesa. 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