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Platelet-rich plasma injection effective alternative for knee OA
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An intra-articular injection of platelet-rich plasma may be an effective alternative to hyaluronic acid in the treatment of knee osteoarthritis, particularly in patients with mild forms of the condition, according to findings published in Arthritis Research & Therapy.
“Although the relevant literature has moderate applicability and strength of evidence, the current guidelines of the American Association of Orthopedic Surgeons do not recommend or oppose the use of [platelet-rich plasma] in the treatment of knee OA,” Ren Yizhong, MD, of the Second Affiliated Hospital of Inner Mongolia Medical University, China, and colleagues wrote. “However, comparison studies conducted on the use of intra-articular injection of [platelet-rich plasma] compared with [hyaluronic acid] for mild or moderate knee OA showed a higher clinical outcome score with [platelet-rich plasma] than with the latter.”
To determine whether platelet-rich plasma is superior to hyaluronic acid in the treatment of knee OA, the researchers in 2016 conducted a systematic review of randomized clinical trials using the Cochrane Central Register of Controlled Trials, PubMed and Embase databases. Focusing on English-language, human in vivo studies that compared platelet-rich plasma treatments to hyaluronic acid, they used the following key words in their search: “Platelet-rich plasma,” “PRP,” “platelet-rich fibrin,” “PRF,” “platelet,” “plasma,” “arthritis,” “osteoarthritis,” “gonarthrosis” and “degeneration.” They also searched presentations and abstracts from the annual meeting of the American Academy of Orthopaedic Surgeons, EULAR, the American Academy of Physical Medicine and Rehabilitation, the American College of Rheumatology and the Osteoarthritis Research Society International.
The researchers identified seven articles, representing 908 patients and 908 knees, that met their inclusion criteria. Outcome measures included efficacy and response to treatment for recovery as defined by the Western Ontario and McMaster Universities Osteoarthritis Index, the International Knee Documentation Committee, the Knee Injury and Osteoarthritis Outcome Score, the EuroQol visual analogue scale and the Tegner score.
According to the researchers, all studies demonstrated statistically significant improvements in clinical outcomes — including pain, physical function and stiffness — with platelet-rich plasma injection. In addition, with the exception of two studies, nearly all showed significant differences between the two treatments regarding clinical outcomes of pain and function.
“[Platelet-rich plasma] intra-articular injection of the knee may be an effective alternative treatment for knee OA, especially in patients with mild knee OA,” Yizhong and colleagues wrote. “However, some studies suggested that [platelet-rich plasma] is not more effective than [hyaluronic acid]. A large, multicenter, randomized trial study is needed to further assess the efficacy of [platelet-rich plasma] treatment for patients with knee OA.” – by Jason Laday
Disclosure: Yizhong reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Andrew L. Concoff, MD, FACR, CAQSM
The impact and importance of a systematic review is dependent upon the quality of the studies included as well as the appropriateness of the interpretation of the body of data assembled; with this in mind, there are several evident concerns regarding the seven articles included in the systematic review by Yalong and colleagues.
For example, the two papers by Filardo and colleagues appear to represent the preliminary results and the complete results of the same trial, respectively, a fact presumably not noted by the authors of the review. Yalong and colleagues did, however, recognize the markedly high risk of bias across all of the trials: Most notably three trials that did not blind subjects or study personnel; four studies with uncertain or high risk of failure of allocation concealment, and; five trials with uncertain or high risk of attrition bias.
When combined with heterogeneity in the preparations of platelet-rich plasma (PRP), the molecular weight of the hyaluronic acid (HA) comparator (for example, low vs. high) and the outcome measures used to assess the patients’ experience of their disease and the effects of its treatment, the conclusions of the authors regarding the relative efficacy of PRP and HA injections must be met with significant skepticism.
Failing to critically interrogate the extant literature regarding PRP for knee OA bears the dual hazard of accepting a treatment that may not be effective as delivered on the one hand, and failing to optimally deliver upon the substantial and widely-recognized therapeutic potential on the other. Accordingly, the key to determining the appropriate role of PRP in the treatment of knee OA lies not in further systematic reviews of the available, flawed studies, but rather — as indicated by the authors — in the conduction of large, well-designed, multicenter trials.
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John R.P. Tesser, MD
In their review, Yalong and colleagues determined that although platelet-rich plasma is apparently effective for some patients in some studies, overall their analysis concludes that it is no worse and no better than hyaluronic acid injections. For those patients who develop OA of the knee and do not live a healthy lifestyle, and especially for those who sustain a knee injury early in life, platelet-rich plasma stands as a possibly effective therapy. However, I think we would all prefer to have better prospective data on this therapeutic intervention.
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