Wang-Saegusa et al investigated 312 patients with knee osteoarthritis. The patients were given 3 injections of plasma-rich plasma at 2-week intervals. At 6 months, the patients reported a significant improvement in pain, stiffness, function, and the Lequesne Index. In another study of 115 knees with osteoarthritis, the subjects received 3 platelet-rich plasma injections every 21 days. A significant improvement was measured in all clinical scores at 6 and 12 months.
A number of theories have been proposed to explain the mechanism by which platelet-rich plasma may improve cartilage healing in cases of osteoarthritis. Proliferation of autologous chondrocytes and mesenchymal stem cells were demonstrated after platelet-rich plasma exposure in an ovine model. Increased hyaluronic acid secretion has also been noted in the presence of platelet-rich rather than platelet-poor preparation. Human osteoarthritic chondrocytes exposed to platelet-rich plasma demonstrated less interleukin-1β-induced inhibition of collagen 2 and aggrecan gene expression, and diminished nuclear factor-B activation, which are pathways involved in osteoarthritis pathogenesis.
This pilot study suggests that platelet-rich plasma may play a role in improving clinical outcomes in patients with early onset osteoarthritis at both 6 months and 1 year. Platelet-rich plasma seemed to result in no change by MRI per knee compartment in at least 73% of cases at 1 year. The limitations of this study included being a limited case series, the absence of a conservatively managed control group, and potential bias in data handling. Further studies are required to fully comprehend the long-term clinical significance of MRI changes seen after platelet-rich plasma therapy for focal early knee osteoarthritis and how this varies to conservatively managed knees.
Institutional review board approval for the study was received.
Clin J Sport Med. 2013;23(3):238-239. © 2013 Lippincott Williams & Wilkins