TNF and osteoarthritis: To evaluate the underlying mechanism, the expressions of Wnt3a in Wnt signaling pathway, together with osteoclastogenesis genes including Nuclear Factor of Activated T-cells cytoplasmic 1 (NFATc1), Receptor Activator for Nuclear Factor-κ B Ligand (RANKL), Tumor Necrosis Factor-α (TNF-α), and Cathepsin K were detected in knee loading effects on a mouse model of osteoarthritis.