[History taking] 1, susceptibility factors: acetabular dysplasia, medical factors, femoral head lesions, hip trauma, endocrine abnormalities and metabolic disorders, age, physique, genetics. 2, symptoms: (1), pain: pain is the main symptom of the disease, and is also the main cause of functional impairment. It is characterized by insidious attacks and continuous dull pain, which mostly occurs after activities and can be relieved by rest. As the disease progresses, joint movement can be limited by pain, and pain can occur even at rest. As the muscles around the joints are damaged during sleep, the protective function of the joints is reduced and the pain-causing activities cannot be restricted in the same way as when awake, and the patient may wake up in pain. (2), Morning stiffness and clinging sensation: Morning stiffness suggests the presence of synovitis. However, unlike rheumatoid arthritis, it is short-lived, usually not exceeding 30 minutes. Adhesive sensation means that after a period of rest, the joint feels stiff when it starts to move, like sticking, and can be relieved with a little movement. The above condition is mostly seen in the elderly and lower limb joints. (3) Other symptoms: As the disease progresses, joint contracture, instability, rest pain, and pain aggravated by weight-bearing may appear. Mechanical atresia may occur due to poor joint surface anastomosis, muscle spasm and contraction, joint capsule contraction, and bone spurs, etc. Physical examination】 1. Systemic examination: body temperature, pulse, respiration, blood pressure, mental ability, body position, facial color, systemic system examination. 2.Specialist examination: (1) Spine shape: increased physiological curvature or deformity. (2) Pressure points: pressure pain at the spinous process and paraspinal process of the lumbar spine. (3) Lumbar mobility: different degrees of lumbar restriction in all directions, obvious in the morning, slightly relieved after activity. (4) Positive 4-character test. Auxiliary tests] 1. Laboratory tests: blood, urine routine, blood lipid, blood sugar, liver and kidney function, electrolyte, blood sedimentation, HLA-B27, CRP, RF, etc. 2. Lumbar spine plain film: blurred subchondral bone margin of sacroiliac joint, bone erosion, blurred joint space, increased bone density and joint fusion. Usually, the degree of lesion of sacroiliac arthritis is divided into 5 grades according to X-ray: grade 0 is normal; grade I is suspicious; grade II has mild sacroiliac arthritis; grade III has moderate sacroiliac arthritis; grade IV is joint fusion ankylosis. Radiographic manifestations of the spine include vertebral osteoporosis and square changes, blurring of the vertebral tubercle, calcification of the paravertebral ligaments, and bone bridge formation. Extensive and severe ossifying bridges in the late stage are called “bamboo-like spine”. Bone erosion of the pubic symphysis, sciatic tuberosity and tendon attachment points (such as the heel bone), with reactive sclerosis and villi-like changes of adjacent bone, and new bone formation may occur. 3.Sacroiliac joint CT: Increased density of sacroiliac joint, blurred joint space, mild bone erosion, obvious destruction and joint fusion. 4.Isotope bone scan: Isotope bone scan cannot be used to diagnose lumbar disc herniation, but it is meaningful in differential diagnosis of bone tumor, ankylosing inflammatory columnitis and intervertebral discitis. 4, sacroiliac joint MRI: subchondral fat accumulation; bone marrow edema; irregular thickening and distortion of cartilage, irregular and fragmented cartilage surface; bone erosion. 5.Ultrasound imaging: suitable for the diagnosis of tendon involvement, tendon telangiectasia, synovitis, bursitis, cysts and erosion and erosion of cartilage and subchondral bone of the joint surface. Therapeutic examinations such as percutaneous puncture and drainage under ultrasound guidance and drug injection are especially suitable for hip joints that are deep or with complex structures and rich local blood flow. 【Diagnosis】 Revised New York criteria (1984): ① the duration of lower back pain lasts at least 3 months, and the pain improves with activity but is not relieved by rest; ② the lumbar spine is limited in movement in the anterior-posterior and lateral flexion directions; ③ the thoracic extension is less than the normal value for the same age and sex; ④ bilateral sacroiliac arthritis grade II-IV, or unilateral sacroiliac arthritis grade III-IV. The diagnosis of ankylosing spondylitis can be confirmed if the patient has ④ and any 1 of ①-③ respectively. Differential diagnosis】 1. Non-specific low back pain: Most patients with low back pain are in this category, which includes: lumbar muscle strain, lumbar muscle spasm, spinal osteoarthritis, cold-irritated low back pain, etc. These low back pain diseases do not have the characteristics of inflammatory low back pain of AS, and can be easily identified by performing sacroiliac joint X-ray or CT examination and performing relevant laboratory tests such as erythrocyte sedimentation rate and C-reactive protein. 2, gluteus myofasciitis: this disease often presents with unilateral upper hip pain, which needs to be differentiated from AS. However, the pain level of this disease is not heavy, generally does not cause difficulty in action, no lying for a long time aggravated characteristics, inflammatory indicators are normal, the sacroiliac joint will not appear lesions. 3, lumbar disc prolapse: disc prolapse is one of the common causes of inflammatory low back pain. The disease is limited to the spine without systemic manifestations such as fatigue, wasting, fever, etc. All laboratory tests including blood sedimentation are normal. The main difference between it and AS can be confirmed by CT, MRI or vertebral canal angiography. 4, iliac dense osteitis: this disease is mostly seen in young women, and its main manifestation is chronic lumbosacral pain and stiffness. There is no abnormality in clinical examination except for muscle tension in the lumbar region. The diagnosis mainly relies on X-ray anteroposterior radiographs, and its typical manifestations are obvious osteosclerotic areas in the iliac bone along the middle and lower 2/3 of the sacroiliac joint, triangular in shape with the tip upward, uniform in density, not invading the sacroiliac joint surface, without joint stenosis or erosion, so it is different from AS. The disease is not characterized by obvious sitting or lying pain for a long time, and the treatment with NSAIDs is not as effective as AS, which is also the point of differentiation between the two diseases. The difference between the two diseases is also evident. For some female patients with early AS, it is difficult to differentiate from this disease. MRI examination of sacroiliac joint may be helpful, but it still needs to be judged by comprehensive clinical situation. Treatment principle】 There is no curative method for AS. However, if patients can be diagnosed and treated reasonably in time, they can achieve symptom control and improve the prognosis. A combination of non-pharmacological, pharmacological and surgical treatments should be used to relieve pain and stiffness, control or reduce inflammation, maintain good posture, prevent deformation of the spine or joints, and correct deformed joints if necessary, in order to improve and enhance the patient’s quality of life. 1.General treatment: educate patients and their families about the disease; advise patients to take physical exercise cautiously and uninterruptedly; try to maintain a posture of chest up, abdomen in and eyes flat in front when standing; reduce or avoid physical activities that cause persistent pain; choose necessary physical therapy (heat therapy, hydrotherapy, infrared, ultra-short wave, electrical stimulation, etc.) for pain in inflamed joints or other soft tissues. 2, drug treatment: ① non-steroidal anti-inflammatory drugs: this class of drugs can quickly improve the patient’s back and hip pain and stiffness, reduce joint swelling and pain and increase the range of motion, whether early or late AS patients are preferred for symptomatic treatment. ②Lyuzosulfapyridine: This drug can improve joint pain, swelling and stiffness in AS, and reduce serum IgA levels and other laboratory activity indicators. It is especially suitable for improving peripheral arthritis in patients with AS, and has the effect of preventing recurrence and reducing lesions in the anterior uveitis complicated by this disease. ③Methotrexate: Methotrexate can be used in patients with active AS when treatment with salazosulfapyridine and non-steroidal anti-inflammatory drugs is ineffective. ④Leflunomide: This drug has better efficacy in peripheral arthritis of AS, and some individual reports can also reduce the progression of inflammation of sacroiliac joints, which is mainly used in the clinical treatment of extraspinal manifestations of AS. ⑤ Glucocorticoids. (6) Traditional Chinese medicine: Chinese traditional acupuncture and moxibustion therapy and traditional Chinese medicine have certain therapeutic effects on AS. 3.Biological agents: The so-called biological agents are monoclonal antibodies or recombinant products of natural inhibitory molecules that selectively target molecules or receptors involved in the immune response or inflammatory process. Biological agents target the pathogenesis of rheumatic diseases, more specific than traditional immunosuppressive therapy, and theoretically, it is possible to control the progression of the disease fundamentally without affecting the normal immunity against infection. The advent of this class of drugs has led to a new phase in the treatment of rheumatic diseases such as AS. A growing body of evidence as well as clinical practice confirms the efficacy of anti-tumor necrosis factor (TNF)-alpha biologics in AS and spondyloarthritis, and they have been found to be more effective in AS and spondyloarthritis than in rheumatoid arthritis. At present, three types of anti-TNF-α biologics have been marketed in China. They are etanercept, infliximab and adalimumab. All three of these anti-TNF-α biologics have a rapid onset of action (a few hours to 24 hours) and good efficacy. Most patients can rapidly obtain significant improvements in their conditions, such as morning stiffness, low back pain, peripheral arthritis, tendon terminal inflammation, chest expansion, ESR and CRP, etc. After a period of application, patients’ physical functions and health-related quality of life are significantly improved, especially some newly emerged dysfunction of spinal activities can be restored. 4.Sacroiliac joint interventional treatment: anti-inflammatory drug injection treatment of lesioned sacroiliac joints under CT guidance has the advantages of small side effects, low dosage and exact efficacy, but it is only effective for patients who have been treated systematically for more than 3 months and whose rheumatic activities are basically controlled; X-ray suggests Ⅰ and Ⅱ degree sacroiliac arthritis lesions. 5, artificial total hip arthroplasty: joint space narrowing, ankylosis and deformity caused by hip joint involvement are the main causes of disability in this disease. For patients with significant narrowing of the hip joint space or femoral head necrosis deformation, artificial total hip replacement can be considered in order to improve the joint function and quality of life. After the replacement, most patients’ joint pain is controlled, some patients’ function is normalized or nearly normalized, and 90% of the life expectancy of the replaced joint is more than 10 years. For patients with more serious deformity of the spine in forward flexion or scoliosis, which leads to obvious obstacles to life, such as the inability to see the road a few meters away, such patients can consider spinal vertebral osteotomy to correct the deformity, but this type of surgery is risky and may cause damage to the spinal cord and lead to lower limb paraplegia, so for those who do not have very serious spinal deformity, surgery is not recommended. The development of the deformity can be slowed or inhibited to a certain extent by physical therapy and rehabilitation exercises under active medical treatment.