Once on the expert outpatient clinic, a young male patient, because of the right knee joint swelling and pain for 1 week consultation, after questioning and found that 3 months ago the patient’s left knee joint swelling and pain surgical history, pathology shows synovitis; at the same time, there is a history of alternating hip area pain for 1 year, relieved by activity, HLAB27 positive, blood sedimentation and C-reactive protein is significantly elevated; MRI of sacroiliac joints show osteomyelitis edema. Diagnosed with spondyloarthritis, the patient was hospitalized for further treatment with a biologic agent (Isapro) combined with NSAIDs, and his symptoms were significantly relieved. He has been followed up in outpatient clinics, and his indicators have returned to normal, and he is able to continue to perform his original job. Comment: Early ankylosing spondylitis should be highly suspected in young men with swelling and pain in a single joint. Do not operate casually, it is best to see a rheumatologist first. Otherwise, not only a waste of money, but also bear the unnecessary physical pain, and even more so when there is a hunchback and joint ankylosis, patients often lose confidence in life…