PRP findings differ by body part

Knee studies do not give one answer

One large knee study compared PRP with a salt-water shot and found no clear difference after twelve months. Other reports favored PRP over joint-gel shots or steroid shots at some times. A steroid shot is medicine used to settle swelling and soreness quickly.

The findings may change with the cause, the amount of arthritis, and how the blood was spun. They don’t prove PRP will help every arthritic knee, so the knee findings remain mixed.

Both answers matter when you decide.

Shoulder findings depend on what is sore

In one shoulder-joint study, people improved after either PRP or a joint-gel shot, but neither choice clearly worked better. Other reports suggest PRP may help some sore shoulder tendons, though the blood was prepared in different ways.

A joint and a tendon are different parts of the shoulder, so your exam must identify which part hurts.

The word shoulder alone does not name the cause.

Heel and back findings are less certain

One heel study found longer improvement with PRP than with a steroid shot. That result applies only to the heel problem studied and does not cover every cause of heel soreness.

Back soreness may come from a disc, joint, muscle, or nerve. Early reports suggest PRP might help some people, but that has not been settled. New weakness, numbness, bladder trouble, bowel trouble, fever, or severe soreness after injury needs urgent care.

A useful answer tells you what changed for people

Ask how much soreness changed, whether people moved better, and when those changes were checked. The answer should also say which findings were unclear.

Bring notes about the motions that hurt, how sleep has changed, and any earlier X-ray. The clinician can then explain whether the people studied had a problem like yours.

Choose only after you understand those limits.

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. The AAOS third-edition clinical practice guideline for non-arthroplasty management of knee osteoarthritis contains 29 recommendations, and the work group explicitly identified intra-articular corticosteroid, hyaluronic acid AND platelet-rich plasma as areas needing better research - including osteoarthritis characterisation, severity stratification, clinically relevant outcomes with controls for bias, and cost-effectiveness analysis. PRP is presented as an open research question in this guideline, not as a settled treatment.

   Brophy RH, Fillingham YA — AAOS Clinical Practice Guideline Summary: Management of Osteoarthritis of the Knee (Nonarthroplasty), Third Edition. Journal of the American Academy of Orthopaedic Surgeons, 2022. DOI: 10.5435/JAAOS-D-21-01233.

3. 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.

4. The American Academy of Physical Medicine and Rehabilitation convened a technical expert panel that ran a structured literature review (2023, updated through June 2025) and a modified Delphi process, and issued five evidence-based clinical recommendations plus 11 consensus-based best practices for PRP in knee osteoarthritis. The statement is explicit that orthobiologic therapies 'remain an evolving area of practice' and that robust, dose-dependent randomized controlled trials are still needed to establish PRP's clinical effects.

   Borg-Stein J, Jayaram P, Colorado BS, et al. — AAPM&R guidance statement on platelet rich plasma for knee osteoarthritis. PM&R, 2026. DOI: 10.1002/pmrj.70144.

5. In a randomized comparative trial of chronic severe recalcitrant plantar fasciitis, the corticosteroid group's mean AOFAS score rose from 52 to 81 at three months but fell back to 58 at 12 months and 56 at 24 months, while the PRP group rose from 37 to 95 at three months and held at 92 at 24 months. The pattern - steroid relief that fades, PRP relief that persists - is the clearest single illustration of the durability difference.

   Monto RR — Platelet-rich plasma efficacy versus corticosteroid injection treatment for chronic severe plantar fasciitis. Foot & Ankle International, 2014. DOI: 10.1177/1071100713519778.

6. A double-blind randomized controlled trial of 70 patients with chronic glenohumeral (shoulder) osteoarthritis compared a single ultrasound-guided injection of leukocyte-poor PRP with hyaluronic acid. There were no differences between the groups on SPADI, ASES or pain scores at any point to 12 months, though both groups improved significantly from 1-2 months onward regardless of osteoarthritis severity. Among the LP-PRP patients, platelet yield had no effect on outcome.

   Kirschner JS, Cheng J, Creighton A, et al. — Efficacy of Ultrasound-Guided Glenohumeral Joint Injections of Leukocyte-Poor Platelet-Rich Plasma Versus Hyaluronic Acid in the Treatment of Glenohumeral Osteoarthritis: A Randomized, Double-Blind Controlled Trial. Clinical Journal of Sport Medicine, 2022. DOI: 10.1097/JSM.0000000000001029.

7. A meta-analysis of eight randomized trials of PRP for rotator cuff tendinopathy concluded PRP was a safe and effective intervention for long-term pain control and shoulder function - while noting that the studies varied in PRP preparation and injection technique and that the control interventions differed between trials (saline in four, rehabilitation or dry needling in the other four).

   A Hamid MS, Sazlina SG — Platelet-rich plasma for rotator cuff tendinopathy: A systematic review and meta-analysis. PLOS ONE, 2021. DOI: 10.1371/journal.pone.0251111.

8. A PROSPERO-registered systematic review of PRP for low back pain graded the quality of the supporting evidence as LEVEL II, reporting positive results in almost all included studies, few adverse events, and low risk of bias in 11 of 13 papers. Applying an adapted MIBO reporting checklist to those studies produced only a 72.7% compliance rate, so even the favourable spine literature is incompletely reported.

   Machado ES, Soares FP, Vianna de Abreu E, et al. — Systematic Review of Platelet-Rich Plasma for Low Back Pain. Biomedicines, 2023. DOI: 10.3390/biomedicines11092404.

9. 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.