Results emphasize importance of placebo controls
In an accompanying editorial by Jeffrey N. Katz, MD, director of the Orthopaedic and Arthritis Center for Outcomes Research at Brigham and Women’s Hospital, professor of medicine and orthopedic surgery at Harvard Medical School, and professor of epidemiology and environmental health at the Harvard T.H. Chan School of Public Health, all in Boston, draws parallels between this study and two earlier studies of platelet-rich plasma for ankle osteoarthritis and Achilles tendinopathy, both published in JAMA in 2021. None of the three studies showed any significant improvements over and above placebo.
Dr. Jeffrey N. Katz
“These findings emphasize the importance of comparing interventions with placebos in trials of injection therapies,” Dr. Katz writes. However, he notes that these studies do suggest possible benefits in secondary outcomes, such as self-reported pain and function, and that earlier studies of the treatment had had more positive outcomes.
Dr. Katz said it was premature to dismiss platelet-rich plasma as a treatment for knee osteoarthritis, but “until a new generation of trials using standardized approaches to PRP [platelet-rich plasma] therapy provides evidence of efficacy, it would be prudent to pause the use of PRP for OA and Achilles tendinitis.”
Not ready to stop using platelet-rich plasma?
When asked for comment, sports medicine physician Maarten Moen, MD, from the Bergman Clinics Naarden (the Netherlands) said the study was the largest yet of the use of platelet-rich plasma for knee osteoarthritis and that it was a well-designed, double-blind, placebo-controlled trial.
Dr. Maarten Moen
However, he also pointed out that at least six earlier randomized, placebo-controlled studies of this treatment approach have been conducted, and of those six, all but two found positive benefits for patients. “It’s a very well-performed study, but for me, it would be a bridge too far to say, ‘Now we have this study, let’s stop doing it,’ ” Dr. Moen said.
Dr. Moen said he would like to see what effect this study had on meta-analyses and systematic reviews of the treatment, as that would give the clearest indication of the overall picture of its effectiveness.
Dr. Moen’s own experience of treating patients with platelet-rich plasma also suggested that, among those who do benefit from the treatment, that benefit would most likely show between 2 and 12 months afterward. He said it would have been useful to see outcomes at 3- and 6-month intervals.
“What I tell people is that, on average, around 9 months’ effect is to be expected,” he said.
Dr. Bennell said the research group chose the 12-month follow-up because they wanted to see if there were long-term improvements in joint structure which they hoped for, given the cost of treatment.
The study was funded by the Australian National Health and Medical Research Council, and Regen Lab SA provided platelet-rich plasma kits free of charge. Two authors reported using platelet-rich plasma injections in clinical practice, one reported scientific advisory board fees from Biobone, Novartis, Tissuegene, Pfizer, and Lilly; two reported fees for contributing to UpToDate clinical guidelines, and two reported grants from the National Health and Medical Research Council outside the submitted work. No other conflicts of interest were declared.
A version of this article first appeared on Medscape.com.