High levels of synovial fluid osteoprotegerin (OPG) and increased serum ratio of receptor activator of nuclear factor-kappa B ligand (RANKL) to OPG correlate with disease severity in patients with primary knee osteoarthritis.

OBJECTIVE: Evaluation of serum and synovial fluid OPG and sRANKL in 37 patients with primary knee osteoarthritis. DESIGN AND METHOD: OPG and sRANKL were measured using ELISA. RESULTS: OPG, sRANKL and sRANKL/OPG were increased in osteoarthritis patients' serum. Synovial OPG was higher than serum OPG, while sRANKL/OPG was higher in the serum; both correlated with disease severity. DISCUSSION: RANKL/OPG pathway is implicated in the pathogenesis of knee osteoarthritis being a suitable target for therapeutic intervention.