What is PRP?
PRP is made from a patient's own blood. The blood is spun in a centrifuge to concentrate platelets and plasma, and the preparation is injected into the knee. PRP is not one uniform product: systems differ in platelet concentration, white blood cell content, activation, injection count, and use of image guidance.
What the evidence suggests
| Question | Current answer |
|---|---|
| Can PRP help symptoms? | Possibly. Trials and meta-analyses report pain or function improvement, but effect size and reliability vary. |
| Is PRP better than gel? | Some analyses favor PRP at later follow-up; individual trials and guideline interpretations differ. |
| Does PRP regrow cartilage? | No reliable evidence shows restoration of normal cartilage or reversal of advanced structural arthritis. |
| Who may be more likely to benefit? | Evidence is most often discussed for symptomatic mild-to-moderate OA; individual prediction remains imprecise. |
| How many injections are best? | Not settled. Studies use different single- and multi-injection protocols. |
Why guidelines disagree
AAOS concludes that PRP may reduce pain and improve function but labels the recommendation limited because of inconsistent evidence. The ACR/Arthritis Foundation recommends against PRP, focusing on heterogeneity and lack of standardization. The practical interpretation is not that PRP is proven useless or superior—it is an elective option with plausible symptom benefit for some patients and meaningful uncertainty.
Who may reasonably consider PRP?
- Knee osteoarthritis is confirmed as the main pain source.
- Exercise, activity modification, and appropriate medication have not provided acceptable relief.
- The patient wants to delay surgery or is not yet an appropriate surgical candidate.
- The patient understands that PRP is symptom treatment—not cartilage restoration—and can accept the cash cost.
Warning signs in a PRP clinic
| A credible provider explains | A warning sign |
|---|---|
| Relevant specialty training and experience diagnosing knee pain | The consultation begins with a package price rather than a diagnosis |
| The preparation system and injection schedule | The clinic cannot describe what is being injected |
| Realistic benefit, uncertainty, and alternatives | Claims of cartilage regrowth, cure, or guaranteed avoidance of surgery |
| Total cost, follow-up, and plan if PRP fails | Pressure to prepay for multiple biologic products |
| Financial or manufacturer relationships | Commercial relationships are hidden or dismissed |
KneeLife standard: Future KneeLife verification will require licensure, diagnosis-first evaluation, protocol transparency, honest claims, total-price disclosure, conflict disclosure, and a plan for nonresponders. Payment will never qualify a clinic.