Podcast episode 112 (in German)
PRP autologous blood – thirty-one questions, twenty-nine without a difference
October 20, 2026
The largest blinded trial ever to test autologous blood against saline in the knee asked 2 main questions and 31 secondary questions. For both main questions and for 29 of the secondary questions it found no difference. This episode explains what that means for PRP and what it does not.
What it is about
In PRP, blood is drawn, spun, and the platelet concentrate injected back, into the knee, the tendon or the scalp. The idea behind it is real: platelets carry growth factors that attract repair cells. The episode examines what of this arrives measurably in the knee, and draws on an Australian trial in which neither the participants nor the injecting doctor nor the assessors knew what was in the syringe. After that it turns to tennis elbow and hair loss, where the picture looks different, and to tolerability, hygiene and costs. Finally, the episode corrects its own database entry, which had listed PRP as “established” for osteoarthritis and tennis elbow.
Key points
- The trial tested 288 people aged 50 and over with mild to moderate osteoarthritis on the inner side of the knee: 3 injections at weekly intervals versus 3 with saline, 12 months of follow-up.
- For pain on a scale of 0 to 10, the difference between the groups was 0.4 points; a noticeable difference would start at 1.8; p equal to 0.17.
- In cartilage volume both groups lost at the same rate, 1.4 versus 1.2 percent; of 31 prespecified secondary questions, 29 showed no difference.
- The result does not fail on execution: 269 of 288 participants stayed to the end, 97 percent received all 3 injections.
- In tennis elbow, 6 randomized trials with 355 patients show no difference versus saline; versus cortisone, autologous blood comes out ahead after six months in 26 trials.
- In hair loss, a pooled analysis of 43 randomized trials with 1,877 participants found greater hair density and less hair loss, but no thicker hair.
- In 32 randomized trials with 1,268 treated knees, adverse events occurred in 18.7 percent, almost exclusively mild pain and swelling; there were no serious events.
Where the data stop
The knee trial applies to one product, one protocol and one indication: leukocyte-poor plasma in mild to moderate osteoarthritis. Anyone who thinks a different preparation would work better would first have to have it tested against saline. For tendons and the scalp the question is open, not settled — at the elbow, PRP wins only against a weak comparator, and for hair the authors call the evidence moderate, with very differently designed studies and nowhere the same preparation.
The real safety problem is hygiene. In New Mexico, HIV infections were diagnosed in 5 people between 2018 and 2023, after cosmetic treatments with microneedles and autologous plasma without a sterilizer and without a license; 198 former clients were followed up. Statutory health insurance does not pay; German practices publicly quote from a good 100 to over 600 euros per session, with 3 sessions being usual. The German orthopedic professional society currently does not recommend the injection; the international osteoarthritis society and the American rheumatologists advise against it.
Listen (in German)
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Published on October 20, 2026.
The topic in the database
- Platelet-rich plasma from your own blood, concentrated and injected back – releases growth factors for joints, skin and hair.PRP (autologous blood therapy)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-22.