Plasma and synovial osteopontin levels, are they associated with disease severity of primary knee osteoarthritis in Egyptian patients?

Aim of the work The aim of this study was to examine osteopontin (OPN) levels in both plasma and synovial fluid of patients with primary knee osteoarthritis (OA) and to investigate their relationship with severity of the disease. Patients and methods Fifty patients with primary knee OA were compared to twenty-five apparently healthy controls. OPN levels in plasma and synovial fluid were measured using enzyme-linked immunosorbent assay. Severity of knee pain was assessed by the Western Ontario and McMaster Universities osteoarthritis index. Radiographic grading of knee OA was performed by Kellgren–Lawrence criteria. Magnetic resonance imaging (MRI) was also performed on painful knees. Results Plasma OPN was higher in patients (159.65 ± 28.56 ng/ml) than controls (90.45 ± 23.63 ng/ml). OPN in plasma and synovial fluid was correlated with severity of knee pain ( r = 0.878, r = 0.795, P < 0.001). Cartilage loss, marginal osteophytes and subchondral bone cyst were the commonest MRI findings in knee OA. MRI detected also patients with early knee OA that were not detected by plain radiography. Conclusion OPN serves as a biochemical marker of disease severity in knee OA. It also could be predictive to the progression of disease.