The Effects of Intra-articular and Peri-articular Platelet-rich Plasma (PRP) Injections ın Chronic Knee Osteoarthritis

The primary objective of this study is to evaluate and compare the effectiveness of ultrasound-guided combined intra-articular and peri-articular platelet-rich plasma (PRP) injections with intra-articular PRP injections alone in patients with chronic knee osteoarthritis (OA). The study specifically examines the effects of these treatment approaches on pain, physical function, activities of daily living, and structural parameters, including medial collateral ligament (MCL) thickness and distal femoral cartilage thickness. Osteoarthritis is a degenerative joint disease characterized by progressive cartilage erosion, osteophyte formation, and subchondral sclerosis, leading to pain, stiffness, and functional disability. It is the most common form of arthritis and a leading cause of disability worldwide, affecting approximately 300 million individuals. Although the knee is the most frequently involved joint, OA is now recognized as a whole-joint disease, involving not only cartilage degeneration but also pathological changes in subchondral bone, synovium, and surrounding extra-articular structures. Platelet-rich plasma is an autologous concentration of platelets suspended in a small volume of plasma and contains a variety of bioactive growth factors, such as transforming growth factor-beta (TGF-β), platelet-derived growth factor (PDGF), and vascular endothelial growth factor (VEGF). These factors play a crucial role in promoting cell proliferation, angiogenesis, and tissue repair. In knee OA, PRP has been shown to reduce matrix metalloproteinase (MMP) activity, particularly MMP-13, enhance endogenous hyaluronic acid production, and support chondrogenesis. Although intra-articular PRP injections are widely accepted as a safe and effective treatment and have demonstrated superiority over placebo and hyaluronic acid in long-term follow-up studies, most existing research has focused exclusively on intra-articular applications. Knee OA is a multifactorial condition frequen