Reactive arthritis (ReA) is a type of arthritis that occurs after infection of certain specific sites (e.g., intestinal and genitourinary tracts). Because of the correlation with human leukocyte antigen (HLA) I B27, the pattern of joint involvement (asymmetric. It is classified as a spondyloarthropathy because of the association with human leukocyte antigen (HLA) I B27, the pattern of joint involvement (asymmetric. predominantly lower extremity joints) and the possible involvement of the spine. It has been referred to as Reiter syndrome (with the classic triad of uveitis, conjunctivitis and arthritis), Fiessinger-Leroy syndrome, etc. In 1969 Ahvonen first allowed it to be named ReA; it has now been widely adopted. Jing Shangfei, Hand and Foot Microsurgery Center of the Second Affiliated Hospital of Inner Mongolia Medical University The disease has two forms of initiation: sexually transmitted deletion and intestinal type. The former card is seen in men aged 20 to 40 years old, and occurs after infection of the genitourinary system by Agrobacterium or Mycoplasma. The latter has an almost equal incidence in men and women, and most of the intestinal infections are Gram-negative bacilli, including Shigella spp, Salmonella spp, Yersinia spp and Campylobacter spp. The development of ReA is associated with infection, genetic markers (HLA-B27) and immune dysregulation. There is an increased incidence of sacroiliac arthritis, ankylosing spondylitis and psoriasis in relatives of patients. The pathognomonic changes in the synovial membrane are non-specific inflammation. Inflammatory lesions of the ligaments and joint capsule attachment points are a common part of ReA lesion activity. The disease is most often seen in young men. The incidence of the disease is 0.06% to l%, and no epidemiological data are available in China.