Diffuse connective tissue disease: systemic lupus erythematosus, rheumatoid arthritis, dry syndrome, systemic sclerosis, polymyositis, dermatomyositis, systemic vasculitis, mixed connective tissue disease, etc. 2, spinal arthropathy: ankylosing spondylitis, Ritter syndrome, psoriatic arthritis, inflammatory bowel disease arthritis. 3, degenerative: osteoarthritis 4, crystalline: gout, pseudogout 5, other: reactive arthritis, rheumatic fever, fibromyalgia syndrome, osteoporosis.