BackgroundPlatelet-rich plasma (PRP), an autologous source of growth factors, can stimulate stem cells and chondrocytes within synovial joints to enhance cartilage regeneration of patients with osteoarthritis (OA).1ObjectivesTo evaluate the effectiveness of intra-articular injection of PRP on clinical improvement of patients with knee OA.MethodsDuring March to December 2013 patients who visited the Rheumatolgy Clinic in Imam Reza Hospital, Mashhad, Iran, with diagnosis of knee OA were interviewed and examined. Patients aged between 45 and 75 years with grade 2 and 3 knee OA according to Kellgren and Lawrence grading scale and without any history of intra-articular injection of hyaluronic acid in the last 6 months before the visit to the clinic were included. Patients with secondary OA, major psychologic disorders, connective tissue disorder, any chronic debilitating disease requiring constant treatment (e.g. malignancies) being under constant treatment with antithrombotic medications and history of allergy to biologic products were excluded. All patients received single injection of 2 mL autologous PRP after signing informed consent. The patients were evaluated prior to injection (baseline) as well as in 3 follow-up visits (1, 3 and 6 months post-injection) according to the following parameters: Persian version of Knee injury and Osteoarthritis Outcome Score (KOOS),2 numerical rating scale (NRS) for subjective measurement of pain, walking time to produce pain and number of stairs to climb to produce pain. Mean differences of parameters among the 4 visits were analyzed using repeated measures ANOVA.ResultsFourteen patients (92.9% women) with mean age of 51.6±7.9 years were studied. By the effect of the treatment, from baseline visit (pre-injection) to 4th visit (6th month post-injection), mean scores of the KOOS subscales significantly improved for pain (42.2±19.9 to 54.2±19.2, p=0.004), activity of daily living (ADL) (43.1±19.3 to 55.6±19.9, p=0.001) and quality of life (QOL) (21.1±18.5 to 32.1±20.7, p=0.04). However, subscales of symptoms as well as sports and recreational activities had no significant change over the 4 visits (Figure 1). Besides, from baseline visit to 4th visit, pain on NRS decreased significantly from 6.1±2.9 to 3.8±1.7 (p=0.02), number of stairs to climb to produce pain significantly increased from 5.1±3.7 to 12.0±6.8 (p=0.04), and the walking time (minute) to induce pain increased from 20.7±15.6 to 38.8±21.0 (p=0.03). No notable adverse events occurred during the 6-month observation.ConclusionsThe intra-articular injection of PRP was clinically effective in knee OA in terms of improvement of pain, ADL, QOL and physical function during 6 months of follow-up. However, long-term follow-up is needed to determine if the clinical response is durable.ReferencesKon E, Buda R, Filardo G, et al. Platelet-rich plasma: intra-articular knee injections produced favorable results on degenerative cartilage lesions. Knee Surg Sports Traumatol Arthrosc. 2010;18:472-9.Salavati M, Mazaheri M, Negahban H, et al....