Arthritis is divided into inflammatory arthritis and non-inflammatory arthritis. In the field of rheumatology, inflammatory arthritis is usually what we refer to as rheumatoid arthritis, while non-inflammatory arthritis, is osteoarthritis. 1. What is osteoarthritis? Osteoarthritis is a common rheumatic disease, with a high prevalence in the elderly and women, and the number of incidences increases with age. The prevalence of osteoarthritis in the knee joint in China is 9.56%, and 78.5% in people over 60 years of age. Osteoarthritis is mainly caused by various reasons such as age, trauma, obesity, genetics and other causes of joint cartilage destruction, lesions occur more in the weight-bearing joints. 2.What is rheumatoid arthritis? Rheumatoid arthritis is a chronic inflammatory disease of the peripheral joints symmetrical polyarticular, and can be accompanied by extra-articular multi-system damage, belongs to the autoimmune connective tissue disease, rheumatoid factor can appear in the serum. The prevalence of rheumatoid arthritis in China is 0.32%-0.34%, with a peak incidence at the age of 40-60, and the incidence in women is 2-3 times higher than that in men. Rheumatoid arthritis mainly involves the synovial membrane, invade the joints and cartilage, resulting in joint deformity, is one of the main diseases that cause disability. 3, the difference between OA and RA? Clinical manifestations: osteoarthritis involves less metacarpophalangeal joints and proximal interphalangeal joints, more weight-bearing joints are mainly involved, such as knee joints, hip joints, etc.; while rheumatoid arthritis involves more metacarpophalangeal joints, proximal interphalangeal joints, wrist joints, metatarsophalangeal joints, etc., some patients can appear temporomandibular joint involvement. Morning stiffness is common and is associated with disease activity. Laboratory tests: rheumatoid arthritis may show positive RF, anti-CCP antibodies, anti-keratin antibodies, anti-perinuclear factor antibodies, while the bone joints are usually negative. Imaging: Rheumatoid arthritis is seen with significant joint destruction, narrowing of the joint space, irregularity of the joint surface, and advanced joint dislocation or bony ankylosis. In contrast, osteoarthritis is mainly characterized by marginal osteophytes and bone formation.