Assessment of Therapeutic Effects of Platelet-Rich Plasma in Knee Osteoarthritis: Possible Role of Inflammatory Cytokines

Osteoarthritis (OA) is a multifactorial disease that commonly affects the knee. Tumor Necrosis Factor-α (TNF-α) regulates inflammation during OA. Macrophage Migration Inhibitory Factor (MIF) may be involved in the pathophysiology of arthritis. Platelet-Rich Plasma (PRP) may reduce pain associated with OA. The present study assessed the possible therapeutic effects of PRP in patients with OA of the knee with varying severities. A prospective study was performed in 90 patients diagnosed with mild (30 cases), moderate (30 cases) and severe (30 cases) knee OA. Three Intra-Articular (IA) injections of PRP were administrated, 2 weeks a part, were received. Pain score and MRI Osteoarthritis Knee Score (MOAKS) were assessed. Serial synovial fluid cytokine assays to measure Tumor Necrosis Factor-α (TNF-α) and macrophage Migration Inhibitory Factor (MIF) were performed using commercially available ELISA kits. The assays were performed pre-injection (S1), 2 weeks after the first IA injection (S2) and 2 weeks after the second IA injection (S3) for all patients. The mean values of pain score and synovial TNF-α and MIF levels were significantly higher (S1, pre-injection) among severe OA than among those with either mild or moderate cases, p˂0.05 for all. Pain score and synovial TNF-α and MIF levels at S3 were significantly lower in those with mild, moderate and severe OA than the corresponding S1 values, (p˂0.05 for all). There was significant improvement in synovitis in both mild and moderate cases, (p˂0.05 for both). The IA injection of PRP reduces synovial fluid TNF-α and MIF levels significantly and exhibit significant therapeutic effects on synovitis by reducing inflammatory cytokine levels and bone marrow lesions primarily for mild knee OA and to a lesser extent for moderate cases.