The results of the first randomized controlled trial looking at the effectiveness of platelet-rich plasma (PRP) are out, and they fail to support the therapy sought by many amateur and professional athletes alike, including Tiger Woods. An injection of PRP was no better than a saline injection in alleviating pain and aiding recovery among a group of Achilles tendonitis sufferers, according to the study published January 13 in the JAMA The Journal of the American Medical Association.

The field of PRP therapy has been in need of this type of rigorous trial in which the therapy was compared to a placebo treatment, Dennis Cardone, a doctor of osteopathic medicine at the New York University Hospital for Joint Diseases, told on December 17. Without these trials, doctors cannot know about the potential effectiveness of PRP, or whether just sticking a needle in an injured site could spur some recovery. Still, Cardone offers platelet injections to patients with diverse injuries who have failed conventional therapies because he says that, in some cases, it does seem to help.

In the current study, researchers treated 54 patients who had suffered from Achilles pain for at least two months. Subjects received an injection of either PRP or saline solution (a placebo). At six, 12 and 24 weeks after the injections, patients in both groups experienced some recovery. The group that received PRP did not, however, report significantly improved pain and activity levels compared with the placebo group.

Johannes Tol, an orthopedic researcher at the Hague Medical Center in the Netherlands and lead author of the study, says that this negative result does not write off platelet injections altogether because the therapy could have different effects on different injuries, The New York Times reported.

Indeed, studies are currently under way to assess the effectiveness of PRP for treating knee and rotator cuff tendon injuries and plantar fasciitis (inflammation of tissue at the bottom of the foots), according to the newspaper.

The results of clinical trials coming out this year could make or break PRP therapy, says Cardone, who is part of a group studying PRP for rotator cuff damage. For certain types of injuries, these studies could inform doctors how to get the best results from PRP.

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