The onset of ankylosing spondylitis after the age of 45 to 50 is called late onset ankylosing spondylitis, and the clinical manifestations are often atypical. The main symptom is lumbosacral pain or low back pain, often aggravated at night, and in severe cases there may be difficulty turning over, waking up with pain during the night and needing to get out of bed to move before going back to sleep. Most of them are accompanied by morning stiffness, and the stiffness is especially obvious when getting up in the morning or after sitting for a long time, which is reduced after activity. There may be band-like chest pain, neck pain and heel and foot pain. Peripheral arthralgia may also be present, with hip osteoarthritis being the most common, and is one of the main causes of disability. Extra-articular manifestations include acute anterior uveitis or iritis, as well as lesions of the ascending aortic root and aortic valve, and conduction block. There are no specific or marker indicators, and rheumatoid factor is negative. C-reactive protein and sedimentation may be elevated during active phase. CT examination of the sacroiliac joint should be performed as a routine examination, and the detection of sacroiliac arthritis is important for the diagnosis of the disease. People suffering from this disease should pay attention to proper gymnastic exercises, pay attention to the correct posture of standing, sitting and lying, and insist on the activities of the spine, thorax and hip joints. It is advisable to sleep on a hard bed with a soft mattress about five centimeters thick and a low pillow. Avoid excessive weight bearing and strenuous exercise. Commonly used drugs include non-steroidal anti-inflammatory drugs, lorazepam, methotrexate, Enova, thalidomide and Ixepam. This disease generally has a good prognosis and is not life-threatening. Special reminder: You need to find a specialist to rule out this disease when you have the following symptoms 1. Young people, with lumbosacral pain. Have difficulty in getting up after sitting for a long time; hand-holding blog standing ; 2.When you get up in the morning, there is a feeling of stiffness in the back; 3.After going to sleep at night, you have difficulty in turning over or wake up with pain at night; 4.Lumbosacral pain or back pain improves after activity or after taking NSAIDs; 5.Young people, have acute iritis; or have unexplained hip or knee swelling and pain; 6.HLA-B27 positive.