Synovitis is a key mediator of osteoarthritis,1 and is involved in the perpetuation of cartilage degradation.2 Synovial inflammation is characterized by mononuclear cell infiltration3 and increases in catabolic cytokines, especially IL‐1β and TNF‐α,4 which are predominantly produced by the synovial macrophages. This evidence concerns the gene TNF and osteoarthritis.