1, the etiology of low back pain: There are many causes of low back pain, including lumbar spondylosis, lumbar muscle strain, osteoporosis and other causes. However, if a young person develops chronic low back pain, which is aggravated by rest or sleep, or even difficulty turning over, and stiffness in the morning, which is relieved by activity, this low back pain is defined as inflammatory low back pain, and the possibility of spondylolisthesis, including ankylosing spondylitis, needs to be alerted. 2. HLA-B27: The HLA-B27 gene is associated with the development of ankylosing spondylitis. Up to 90% of patients with ankylosing spondylitis express this gene positively. However, this does not mean that all positive individuals will develop the disease. Therefore, the disease cannot be diagnosed simply by a positive gene. As a genetic gene, the positive expression cannot be changed even after treatment. 3, sacroiliac joint examination: Sacroiliac joint examination is very important and necessary to confirm the diagnosis of spondylolisthesis or ankylosing spondylitis. Doctors will choose the appropriate examination methods, including plain films, CT, MRI, etc., based on age, disease duration, symptoms, and concomitant conditions. The final diagnosis often relies on symptoms, imaging, and a combination of test results.