Plasma and Synovial Fluid Sclerostin Are Inversely Associated with Radiographic Severity of Knee Osteoarthritis

Objective: The purpose of this study was to analyze sclerostin in plasma and synovial fluid of knee osteoarthritis (OA) patients and to investigate the association between sclerostin levels and radiographic severity.

Design And Methods: A total of 190 subjects (95 knee OA patients and 95 healthy controls) were recruited in the present study. Sclerostin levels in plasma and synovial fluid were assessed using an enzyme-linked immunosorbent assay. OA grading was performed using the Kellgren-Lawrence classification.

Results: Plasma sclerostin levels were significantly lower in OA patients than in healthy controls (P=0.004). Additionally, sclerostin levels in plasma were significantly higher with respect to paired synovial fluid (P<0.001). Moreover, sclerostin levels in plasma and synovial fluid demonstrated a significant inverse correlation with the radiographic severity of knee OA (r=-0.464, P<0.001 and r=-0.592, P<0.001, respectively). Subsequent analysis revealed that there was a positive correlation between plasma and synovial sclerostin levels (r=0.657, P<0.001).

Conclusions: Sclerostin was significantly lower in OA plasma samples when compared with healthy controls. Plasma and synovial fluid sclerostin levels were inversely associated with the radiographic severity of knee OA. Therefore, sclerostin may be utilized as a biochemical marker for reflecting disease severity in primary knee OA.