CX3CL1 and osteoarthritis: The correlation between radiographic progression of osteoarthritic lesions according to the Kellgren-Lawrence grading scale (KLGS) (Kellgren and Lawrence 1957) and CX3CL1 levels in venous blood and synovial fluid was analysed by Zou et al. (2013) in a study of 223 patients with osteoarthritis meeting the criteria of the American College of Rheumatology (Altman et al. 1986).