Correlation of inflammatory mediators with osteophyte formation in end-stage knee osteoarthritis

Osteoarthritis (OA) is a prevalent degenerative joint disorder with varying clinical and radiological presentations. This study aimed to investigate the relationship between pro-inflammatory mediators in serum and synovial fluid (SF) and osteophyte size in patients with end-stage knee OA. Forty-four patients (58 knees) who underwent total knee arthroplasty were included. Serum and SF levels of matrix metalloproteinase-1 (MMP-1), interleukin-8 (IL-8), and interleukin-18 (IL-18) were measured using enzyme-linked immunosorbent assay. Radiographic parameters, including osteophyte size, were assessed using on standing anteroposterior knee X-rays. Pearson's and partial correlation analyses were used to evaluate associations. A positive correlation was found between serum and SF IL-18 levels (r = 0.64, P < 0.001) and between SF MMP-1 and IL-8 levels (r = 0.28, P = 0.03). A significant positive correlation was found between patient age and femur osteophyte size (r = 0.32, P = 0.02). SF IL-18 levels positively correlated with both femur (r = 0.36, P = 0.005) and tibia (r = 0.28, P = 0.04) osteophyte sizes. The partial correlation between SF IL-18 and femur osteophyte size remained significant after adjusting for age (r = 0.3, P = 0.02) and body mass index (r = 0.38, P = 0.003). Elevated SF IL-18 levels were associated with increased osteophyte size in patients with end-stage knee OA, suggesting a potential role for IL-18 in osteophyte formation. Elevated SF IL-18 levels may reflect underlying inflammatory activity in OA and could serve as a potential biomarker or therapeutic target in advanced disease.