Assessment of synovial repair in primary knee osteoarthritis after platelet rich plasma (PRP) intra-articular injection

Primary knee osteoarthritis (KOA) is a persistent condition marked by the gradual deterioration of the joint and cartilage loss on its surfaces. Recently, platelet-rich plasma (PRP) was considered a biological intervention that alleviates symptoms and restricts the advancement of primary KOA in patients. This study aimed to evaluate the effect of intra-articular PRP injections on synovial repair through cytokine assays in 20 patients with primary KOA. Patients received two intra-articular PRP injections, spaced one month apart. The role of PRP was assessed by measuring Transforming growth factor beta (TGF-β) and interleukin-17 (IL-17) levels in synovial fluid before and after the injections. Both visual analogue scale and Western Ontario and McMaster Universities Osteoarthritis index were assessed before and after intervention. IL-17 and TGF-β levels were measured in the synovial fluid using sandwich ELISA technique before the first PRP intra-articular injection and one month after the second injection to assess the synovial repair after PRP injection. Our results showed that the synovial IL-17 levels significantly decreased by 75.21% (p < 0.0001) after intra-articular knee injection, dropping from a range of 102.3-293 (median 173.5: 139.7- 224.5) to 17.86-106 (median 36.38: 23.57- 50.32). In contrast, synovial TGF-β levels significantly increased by 80.3% (p < 0.0001) after intra-articular knee injection, rising from 124-545.5 (mean ± SD: 256.22 ± 123.56) to 693.3-3226 (mean ± SD: 1521.6 ± 765.46). In conclusion, intra-articular PRP administration in primary KOA patients is associated with increased levels of TGF-β and decreased levels of IL-17 in the synovial fluid of the joint. These changes in cytokine levels suggest that PRP treatment effectively reduces inflammation and may contribute to pain relief in primary KOA.