# PRP, a shot made from prepared blood, may ease soreness but can't promise a result *What PRP Can And Cannot Do | PRP Clinic Scottsdale* > What a prp injection success rate means, why PRP results differ, and how prp vs cortisone differs in timing. This page explains what a blood-based PRP shot may change and what it can't promise. ## PRP may help soreness, but the research doesn't agree PRP comes from blood drawn from the arm and spun into layers. Staff keep the portion with extra platelets, the small blood cells that clump at a cut and help start repair. Some knee studies found less soreness and easier movement. Another compared PRP with a salt-water shot and found little difference. Salt water gives both groups a shot, so any added change can be tied more fairly to PRP. Research hasn't shown PRP rebuilding cartilage, the smooth cover on bone ends. It also can't promise that surgery will be avoided. The honest result is a change you can feel, not a perfect X-ray. ## A prp injection success rate only helps when success is defined Success might mean less soreness, an easier walk or no further shot. Those are different results. A clinic percentage means little without the number of people counted and the date they were asked. Find out what counted as improvement and how long it lasted. Then choose two tasks you want to change, such as reaching the mailbox or sleeping through the night. Tell the clinic what change would make the cost and sore days worthwhile. One percentage can't predict what will happen in your joint. ## prp vs cortisone is often a choice between faster and slower relief Cortisone often eases soreness sooner and may fade sooner. PRP can take more time to judge. Neither shot fits every person, and an earlier result matters. Tell the doctor what happened after past shots. Current medicine, bleeding trouble and infection can also change the advice. A doctor may say no when soreness isn't from the joint or a nearby tendon, which joins muscle to bone. The answer may also be no when another health concern makes the shot unsafe. A clear no means PRP doesn't fit what the doctor found. ## 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](https://pubmed.ncbi.nlm.nih.gov/34812863/). *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](https://pubmed.ncbi.nlm.nih.gov/32302218/). *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](https://pubmed.ncbi.nlm.nih.gov/41031623/). *EFORT Open Reviews*, 2025. DOI: 10.1530/EOR-2025-0022. 4. The 2019 ACR/Arthritis Foundation osteoarthritis guideline makes STRONG recommendations for exercise, weight loss in people with overweight or obesity, self-management programmes, tai chi, cane use, tibiofemoral bracing, topical and oral NSAIDs and intra-articular glucocorticoid injections for knee OA. Its conditional recommendations cover balance exercises, yoga, CBT, acupuncture, thermal modalities, radiofrequency ablation, acetaminophen, duloxetine and tramadol. Anything offered before a course of the strongly recommended options is being offered out of order. Kolasinski SL, Neogi T, Hochberg MC, et al. — [2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee](https://pubmed.ncbi.nlm.nih.gov/31908163/). *Arthritis & Rheumatology*, 2020. DOI: 10.1002/art.41142. 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](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/classification.cfm?ID=JQC). *FDA accessdata (CDRH device databases)*, 2003. 6. FDA states verbatim of stem cell, stromal vascular fraction, umbilical cord blood, Wharton's jelly, amniotic fluid and exosome products: 'None of these products have been approved for the treatment of any orthopedic condition, such as osteoarthritis, tendonitis, disc disease, tennis elbow, back pain, hip pain, knee pain, neck pain, or shoulder pain.' The only FDA-approved stem cell products in the United States are blood-forming cells from umbilical cord blood, approved only for disorders of blood production, and there are no FDA-approved exosome products. PRP is a different product from all of these and the categories must not be blurred in either direction. U.S. Food and Drug Administration — [Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes](https://www.fda.gov/vaccines-blood-biologics/consumers-biologics/consumer-alert-regenerative-medicine-products-including-stem-cells-and-exosomes). *FDA (Center for Biologics Evaluation and Research)*, 2020. 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](https://pubmed.ncbi.nlm.nih.gov/38961773/). *Knee Surgery, Sports Traumatology, Arthroscopy*, 2024. DOI: 10.1002/ksa.12320. ## If soreness stays, an exam can show whether PRP fits At QC Kinetix, medical providers are the health workers who examine the joint and give care. When you call, ask whether a doctor will examine you and who gives the shot. Regenerative treatment options include PRP, made from blood drawn and prepared in the office. The Scottsdale office is at 9220 E. Mountain View Road, Suite 210, just north of Shea Boulevard and east of Loop 101. One number reaches every Phoenix-area office, (602) 837-PAIN. The visit may end with PRP, more home care or a different kind of help. Book a free consultation: --- Clear answers for a sore joint. Plain answers about sore joints, PRP visits, home care, cost, and the Scottsdale office. Plain answers about joint soreness, PRP visits, recovery and the Scottsdale office. This site is operated by the owners of the QC Kinetix Phoenix-area clinics, including the Scottsdale office on Mountain View Road that these pages point to. It is first-party education rather than a review site or a survey of the market, and the clinic it recommends is one we hold a direct commercial interest in. Copyright 2026 prpclinicscottsdale.com. Educational content only. Nothing here is medical advice, a diagnosis, or a substitute for assessment by a clinician who can examine the joint in question.