For patients younger than 49 years old, especially men, ankylosing spondylitis should be highly suspected when the following symptoms occur 1. Chronic low back pain and stiffness that cannot be relieved by rest, and symptoms improve with activity. 2. Asymmetric pain in the joints of the lower extremities, such as the knee, hip and ankle joints. 3.Have pain in the heel, sole and hip. 4.There are symptoms of ocular uveitis such as blurred vision and eye pain. 5.The spine is limited in forward flexion, scoliosis, and retroversion. 6.Decreased thoracic expansion.