Relationship between increased serum & synovial fluid decorin levels & knee osteoarthritis

BACKGROUND & OBJECTIVES: Decorin is a proteoglycan that plays a role in the binding of collagen and has an important role in the pathogenesis of osteoarthritis (OA). This study was aimed to determine serum and synovial fluid decorin levels in patients with knee OA and to investigate whether these levels were associated with OA and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score. METHODS: In this prospective study 88 participants were included (44 knee OA and 44 with other knee joint diseases) in the study and control groups. Knee function was assessed using the WOMAC score. The serum and synovial fluid decorin levels were analyzed using a human decorin ELISA. Binary logistic regression with a single and multi-categorical predictor was used to determine the possible risk factors for OA. RESULTS: The serum decorin levels were significantly higher in the OA group than the control group (P<0.002). The synovial fluid decorin levels were not significantly different between OA and control groups. WOMAC score [odds ratio (OR)=1.073, 95% confidence interval (CI): 1.032-1.116, P<0.001] and high serum decorin levels (OR=1.114, 95%CI: 1.030–1.205, P=0.007) were found to be significant in the determination of OA. Serum decorin levels were positively correlated with the WOMAC score in OA. INTERPRETATION & CONCLUSIONS: An increased serum decorin levels may be indicative of changes in extracellular matrix structure. The positive correlation between serum decorin level and WOMAC score supports this result. Increased serum decorin levels and WOMAC score were found to be risk factors associated with OA. However, the decorin level in the joint fluid was not associated with OA.