(a) Recurrent occult, dull or sharp pain in the low back. The low back pain of AS is inflammatory pain. It manifests as pain at rest, which is relieved or relieved after activity. There is also pain that is more pronounced at night, and some patients will wake up with pain after sleeping into the night, and the pain can be relieved after getting out of bed and walking and moving around for a few steps before they can sleep again. How to identify inflammatory low back pain? The following 5 items can help distinguish inflammatory back pain caused by AS from non-inflammatory back pain caused by other causes: (1) back discomfort occurred before the age of 40; (2) slow onset; (3) symptoms persist for at least 3 months; (4) back pain with morning stiffness; (5) back discomfort decreases or disappears after activity. Four of the above five items are consistent with inflammatory back. (2) Those with frequent radiating pain in the sacroiliac joint, hip, thigh root, and knee. The pain often alternates between right and left. (C) Recurrent joint pain and swelling in the extremities are often diagnosed as synovitis. Peripheral joint lesions predominate in 24% to 75% of AS patients, with the knee, hip, ankle and shoulder joints predominating, and occasional involvement of the elbow and small joints of the hand and foot. Asymmetric, few-joint, single-joint, and large-joint arthritis of the lower extremities are present. Hip joint involvement accounts for 38% to 66% of the cases, and is the main cause of disability, manifesting as local pain, restricted movement, flexion contracture and joint ankylosis, most of which are bilateral, and 94% of the hip symptoms start within the first 5 years after the onset of the disease, and the younger the age of onset, the more likely the hip lesions occur in peripheral joints. (d) Recurrent ocular symptoms such as eye pain, tearing, photophobia and pericorneal congestion, iris edema, etc. If you have frequent eye discomfort, you should also consult a rheumatologist to see if you are suffering from rheumatism. Because acute anterior uveitis and iritis are common extra-articular manifestations of AS, ¼ of patients develop uveitis during the course of the disease, alternating unilaterally or bilaterally, which usually resolves on its own, and repeated episodes can lead to visual impairment. (E) Recurrent heel pain, chest pain, and cervical stiffness. Heel pain is often the first symptom of many AS patients. It is an inflammation of tendons, ligaments and bone attachment points, which is a characteristic pathological change of AS. It can be seen in the thoracic rib joint, rib cartilage, stalk-thoracic joint, spondylolisthesis, iliac crest, greater trochanter, sciatic tuberosity, tibial tuberosity, Achilles tendon and pubic symphysis, etc. Patients can have pain in the corresponding areas, such as chest pain, heel pain, etc. Chest pain is sometimes misdiagnosed as “pleurisy Chest pain is sometimes misdiagnosed as “pleurisy”, “pericarditis”, “atypical angina” and referred to a chest or cardiovascular doctor. These are the common clinical manifestations of AS. In addition, AS can cause nerve, muscle, lung, cardiovascular and kidney damage.