Plasma-rich platelet injection, an arthritis therapy, is thought to induce regeneration of damaged cartilage. A Netherlands team looked at existing studies and was not convinced that there is credible proof the therapy works. The studies all had a high-to-moderate risk of bias, they found.
Injecting platelet-rich plasma (PRP) into arthritic knees is the latest treatment for osteoarthritis (OA). It has also been used to treat other injuries and conditions like tennis elbow and plantar fasciitis.
The idea is that platelets contain growth factors, cytokines, chemokines and dense and lysosomal granules that may repair the damaged cartilage in OA.
That could be promising, particularly for patients with early to moderate OA.
Training and equipment for physicians who want to do PRP injections is widely available, and patients can easily find centers that offer the therapy.
But does it work?
Skeptical that existing studies are likely biased, a Netherlands team reviewed the literature to do a meta-analyses. Reporting today in the British Journal of Sports Medicine, Augustinus Laudy and colleagues at the department of sports medicine at Bergman Clinics, Naarden, NL, looked at 10 trials.
They found problems with study design, lack of research addressing key questions, and confirmed that there is likelihood of bias in the studies.
All showed that PRP reduced pain more effectively than did placebo or hyaluronic acid injections.
Patients who had PRP shots also showed more improvement in joint function.
Nonetheless, the team concluded that because of high-to-moderate risk of study bias, more large randomized studies need to be completed to see if the findings hold up.
Osteoarthritis is common in people 65 and over and often leads to knee replacement surgery. American College of Rheumatology guidelines call for exercise, weight loss, and pharmacological therapies including NSAIDs and corticosteroid injections. But the lifestyle modifications appear to have low rates of success and the drug remedies have only temporary benefits and come with side effects and risks.
PRP therapy involves taking autologous blood and using a centrifuge or cell separator to extract platelets.
Related therapies use platelet-leucocyte gel, and plasma rich in growth factors.
The team evaluated existing studies of PRP therapy based on study design, details of interventions, primary and secondary outcome measures, size of the study, and p values.
They then judged the strength of the evidence presented.
Of 10 studies that met the team’s review criteria, all showed “a general positive effect on pain reduction and function” in PRP vs. controls and a moderate effect compared to placebo or HLA.
They attempted to learn whether reported effectiveness varied with severity of OA, but found none of their 10 studies satisfactorily addressed that topic. Another flaw in the studies was that they did not address questions regarding optimal platelet concentration, activation procedure, inclusion or exclusion of leucocytes, how to best prepare the product, how often it should be administered, and the optimal dosage.
Though the studies showed “significant effect on pain” with PRP injections, larger studies with low risk of bias are needed, they wrote.