TNF and synovitis: Previous studies have shown that cytokines, such as IL-1β, IL-6, TNF-α, IL-17A and IP-10 in ankle joints are significantly increased during the development of arthritis [37, 38], TNF-α and IL-1β may cause synovitis and bone and cartilage damage, then aggravating the incidence of arthritis [39]; IL-17A triggers changes in the synovium that lead to synovitis and maintain local inflammation.