High levels of synovial fluid osteoprotegerin (OPG) and increased serum ratio of receptor activator of nuclear factor-κB 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 patientsʹ 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.