Injections of platelet-rich plasma are no better than placebo for helping reduce knee pain in people with knee joint osteoarthritis


Injections of platelet-rich plasma are no better than placebo for helping reduce knee pain in people with knee joint osteoarthritis, an Australian clinical trial led by researchers at the University of Melbourne, University of Sydney and Monash University has found.

Knee joint arthritis affects more than two million Australians with platelet-rich plasma injections becoming a popular form of treatment for painful joints in recent years. Platelet-rich plasma uses a concentration of a patient’s own platelets injected directly into the joint with the aim being to aid in long-term pain relief and to improve joint cartilage.

The research, published in the Journal of the American Medical Association, compared a series of three-weekly injections of platelet-rich plasma to three-weekly injections of saline, which acted as a placebo for the study.

Participants and injecting doctors were not aware of whether there was platelet-rich plasma or saline in the syringe during the injections. Participants were tracked for pain levels and cartilage health over 12 months.

Researchers found that while participants who received platelet-rich plasma injections had a significant improvement in their knee pain over 12 months, the level of improvement was matched by those in the placebo group. There were no differences identified in the MRI scans across both groups.

“We conducted the study because there is currently limited high-quality evidence about whether or not platelet-rich plasma injections have benefits for people with painful knee osteoarthritis.

Our results do not support the use of platelet-rich plasma for people with mild to moderate knee osteoarthritis,” University of Melbourne lead researcher Professor Kim Bennell said.

Professor Bennell advises people with knee osteoarthritis to use treatments such as exercise and, if they are above a healthy weight range, weight loss to help manage their symptoms and improve their quality of life.

Contributing author Professor David Hunter, from the University of Sydney, said Osteoarthritis (OA) is a common and disabling disease. “Pain in OA is a substantial unmet need, so identifying new therapies capable of improving the symptoms and structure are urgently needed. Unfortunately, the particular treatment trialed in this study, PRP, whilst widely used and typically expensive, appears to be ineffective compared to an inert comparator.”

Two hundred and eighty-eight people with mild to moderate knee osteoarthritis participated in the RESTORE study, conducted in both Melbourne and Sydney, with funding from the National Health and Medical Research Council.

And ….

Efficacy of platelet-rich plasma and plasma for symptomatic treatment of knee osteoarthritis: a double-blinded placebo-controlled randomized clinical trial


Platelet-rich plasma (PRP) has a still conflicting efficacy for knee osteoarthritis (KOA) and might be a minimally invasive and safe treatment alternative. The potential benefit of only plasma (non-enriched) has never been investigated. Our aim was to evaluate the efficacy of intra-articular platelet-rich plasma (PRP) and plasma to improve pain and function in participants with KOA over 24 weeks.


Randomized, double-blind, placebo-controlled trial with 3 groups (n = 62): PRP (n = 20), plasma (n = 21) and saline (n = 21). Two ultrasound-guided knee injections were performed with a 2-week interval. The primary outcome was visual analog scale 0-10 cm (VAS) for overall pain at week 24, with intermediate assessments at weeks 6 and 12. Main secondary outcomes were: KOOS, OMERACT-OARSI criteria and TUGT.


At baseline, 92% of participants were female, with a mean age of 65 years, mean BMI of 28.0 Kg/m2and mean VAS pain of 6.2 cm. Change in pain from baseline at week 24 were -2.9 (SD 2.5), -2.4 (SD 2.5) and -3.5 cm (SD 3.3) for PRP, plasma and saline, respectively (p intergroup = 0.499). There were no differences between the three groups at weeks 6 and 12. Similarly, there were no differences between groups regarding secondary outcomes. The PRP group showed higher frequency of adverse events (65% versus 24% and 33% for plasma and saline, respectively, p = 0.02), mostly mild transitory increase in pain.


PRP and plasma were not superior to placebo for pain and function improvement in KOA over 24 weeks. The PRP group had a higher frequency of mild transitory increase in pain.

reference link :

More information: Kim L. Bennell 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, Journal of the American Medical Association (2021). DOI: 10.1001/jama.2021.19415


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