Ankylosing spondylitis, also known as Marie-strümpell disease, Von Bechterew disease, rheumatoid spondylitis, deforming spondylitis, and rheumatoid central, is now known as AS. AS is characterized by inflammation and ossification of the spinal joints and ligaments of the lumbar, cervical, and thoracic segments, as well as the sacroiliac joints, with frequent involvement of the hip and inflammation of other peripheral joints. The disease is generally rheumatoid factor-negative and is therefore considered a seronegative spondylosis along with Reiter’s syndrome, psoriatic arthritis, and enteropathic arthritis. Ankylosing spondylitis is actually a very ancient disease, with evidence of ankylosing spondylitis found in bones from ancient Egyptians thousands of years ago. 2000 years ago, the famous Greek physician Hippocrates described a disease in which the affected person had pain in the sacrum, spine, and cervical spine. Clinical manifestations AS is common in young people between 16 and 30 years of age, and is more common in men, with a rare first onset after age 40, accounting for about 3.3%. The disease starts insidiously, progresses slowly, and the systemic symptoms are mild. In the early stage, there is often lower back pain and morning stiffness, which is relieved after activity, and may be accompanied by low fever, fatigue, loss of appetite, wasting and other symptoms. The pain is intermittent at the beginning and develops into persistent after several months and years. Later, the inflammatory pain disappears, the spine is partially or completely straightened from the bottom up, and a hunchback deformity appears. Peripheral joint invasion is more common in female patients, with slower progression and less spinal deformity. The majority of patients with AS have arthropathy, and most of them first invade the sacroiliac joint, and later develop upward to the cervical spine. In a few patients, the cervical spine or several spinal segments are invaded at the same time, and the surrounding joints may also be invaded. In the early stage, there is inflammatory pain in the joints, accompanied by muscle spasm around the joints and a feeling of stiffness, which is obvious in the morning; it may also be manifested as night pain, which is relieved by activities or painkillers. As the disease progresses, the joint pain decreases, while the movement of each spinal segment and joint is restricted and deformed, and in advanced stages the entire spine and lower limbs become strongly bowed and flexed forward. (1) Sacroiliac arthritis: About 90% of AS patients first present with sacroiliac arthritis. Later, it progresses upward to the cervical spine and manifests as recurrent lumbar pain, lumbosacral stiffness, intermittent or alternating lumbar pain and hip pain on both sides, which may radiate to the thighs, without positive signs and negative extension and leg lift test. However, direct pressure or extension of the sacroiliac joint can cause pain, so it is not like sciatica. Some patients have no symptoms of sacroiliac arthritis and only abnormal changes are found on X-ray. About 3% of the AS cervical spine is involved at the earliest and later progresses down to the lumbosacral region, while 7% of the AS has several spinal segments involved at the same time. (2) Lumbar spine lesions: when the lumbar spine is involved, most of them show restricted lower back anterior and lumbar activities. The lumbar spine is involved in anterior flexion, inflexion, and scything of Liao Wei brake (11). If the cribriform joints, sternal stalk joints, sternoclavicular joints [19, 20] and intercostal cartilage joints are involved, there is a bundle-like chest pain, limited thoracic expansion, and the chest pain increases when inhaling and coughing or sneezing. In severe cases, the thorax remains in the state of exhalation, and the thoracic expansion is reduced by more than 50% compared with normal people, so that it can only be assisted by abdominal breathing. Due to the reduction of thoracic and abdominal cavity capacity, it causes cardiopulmonary and digestive dysfunction. (4) Cervical spine lesions: A few patients first present with cervical spondylitis, with pain in the cervical spine first, radiating along the neck to the head and arms. The neck muscles start with spasm and later atrophy, and the lesion progresses to cervicothoracic posterior convexity deformity. Head movement is significantly restricted, often fixed in a forward-flexed position, unable to supinate, lateral bend or rotate. Severe cases can only see a small piece of ground in front of their toes, and cannot raise their heads to look flat. (5) Peripheral arthropathy: About half of the patients with AS have transient acute peripheral arthritis, and about 25% have permanent peripheral joint damage. It usually occurs more often in the large joints and more in the lower extremities than in the upper extremities. Some statistics show that the rate of peripheral joint involvement is 40% for the hip and shoulder, 15,5 for the knee, 10% for the ankle, 5% for the foot and wrist, and very rarely for the hand. In 80 cases of AS, the involvement rate of hip joint was reported (100%); limitation of movement (64%), flexion contracture (38%), muscle atrophy (25%), and joint ankylosis (37%) were the main causes of disability in AS patients; 94% of the hip symptoms appeared within 5 years after the onset of the disease, suggesting that if the hip joint is not involved in the first 5 years of AS, it is unlikely to be involved later. When the shoulder joint is involved, the pain is more pronounced when the joint is restricted, and activities such as combing the hair and lifting the hand are restricted. When the knee joint is involved, the joint is compensated for bending, making daily life such as walking and sitting more difficult. It rarely affects the elbow, wrist and foot joints, and is even rarer when it affects some of the joints. In addition, the pubic symphysis may be involved, and the upper pelvic rim, sciatic tuberosity, greater trochanter of the femur, and heel of the foot may have osteoarthritic symptoms, with early manifestations of local soft tissue swelling and pain, and later bony enlargement. In general, peripheral arthritis can occur before or after spondylitis, and local symptoms are not easily distinguishable from rheumatoid arthritis, but there are fewer remaining deformities. The extra-articular manifestations of AS mostly appear after spondylitis, and occasionally extra-articular symptoms occur months or years before skeletal muscle symptoms.AS can invade multiple systems throughout the body and is associated with a variety of diseases. (1) Cardiac lesions: Aortic valve lesions are more common, and according to autopsy, about 25% of AS cases have aortic radiculopathy, and cardiac involvement can be clinically asymptomatic or significant. About 1% of the cases have varying degrees of aortic valve incompetence; about 8% have heart block, which can coexist with aortic valve incompetence and occur alone, or in severe cases, complete atrioventricular block and A.I.S. syndrome. Angina pectoris may occur when the lesion involves the coronary artery. Rarely, aortic myocardial aneurysm, pericarditis and myocarditis occur. Patients with AS with combined heart disease are generally older, have a longer medical history, more spondylitis and peripheral joint lesions, and more pronounced systemic symptoms. gould [24] et al. examined the cardiac function of 21 patients with AS and found that the cardiac function of AS patients was significantly lower than that of the control group. (2) Ocular lesions: long-term with the room, 25% of AS patients have conjunctivitis, iritis, uveitis, or uveitis, the latter occasionally complicated by spontaneous anterior chamber hemorrhage. Iriditis is prone to recurrence, and the incidence increases the longer the disease is present, but is not related to the severity of spondylitis, which is common in those with peripheral arthropathy and may occur in a few cases before spondylitis. Ocular disease is often self-limiting, sometimes requiring corticosteroid treatment, and some can lead to glaucoma or blindness without proper treatment. (3) Ear lesions: Gamilleri et al. reported that chronic otitis media occurred in 1/2 of 42 patients (29%) with AS, which is 4 times more than normal controls, and that there were significantly more extra-articular AS patients with chronic otitis media than AS patients without chronic otitis media. (4) Pulmonary lesions: A small number of patients with AS may be complicated by speckled irregular fibrotic lesions in the upper lobe of the lungs, manifested by coughing, shortness of breath, or even hemoptysis, and may be accompanied by recurrent pneumonia or pleurisy. x-ray examination shows diffuse fibrosis in the upper lobe of the lungs bilaterally, which may have cyst formation and parenchymal destruction, similar to tuberculosis, and needs to be differentiated. (5) Neurological lesions: due to spinal ankylosis and osteoporosis, cervical dislocation and spinal fracture can easily occur and cause spinal cord compression; if intervertebral discitis occurs, it can cause severe pain; in the late stage of AS, it can invade the cauda equina and cauda equina syndrome can occur, resulting in neurogenic pain in the lower limbs or buttocks; loss of infection in the sacral nerve distribution area, weakened Achilles tendon reflex and motor dysfunction such as bladder and rectum. (6) Amyloidosis: a rare complication of AS. Among 35 cases of AS, routine rectal mucosal biopsy was reported to find amyloid deposits in 3 cases, mostly without specific clinical manifestations. (7) Renal and prostatic lesions: compared with RA, renal impairment rarely occurs in AS, but IgAD nephropathy has been reported. chronic prostatitis is higher in AS compared with controls, the significance of which is unknown. The initial symptoms of ankylosing spondylitis Because ankylosing spondylitis is a relatively common disease with a lingering course and a tendency to cause disability, early diagnosis and treatment should be pursued. Young people aged 16-25, especially young men, should be particularly alert to the possibility of ankylosing spondylitis if the following symptoms occur (1) Low back pain and lumbar stiffness for more than 3 months, which cannot be relieved by rest. (2) Unilateral or bilateral sciatica without a history of significant trauma or sprain. (3)Recurrent episodes of knee or ankle joint swelling and pain, joint effusion, without obvious history of trauma or infection. (4)Recurrent episodes of heel node swelling and pain or heel pain. (5) Recurrent episodes of iritis. (6) No cough or other respiratory symptoms, chest pain and girdling sensation without history of trauma, and limited thoracic movement. (7) Spinal pain, stiffness, and even limited movement function without any obvious history of trauma or sprain. (8) Bilateral hip and hip pain without obvious history of trauma or strain. (9) Sudden onset of pain, swelling, and activity dysfunction in the large joints of the spine and extremities. Ankylosing arthritis generally has an insidious onset and may not have any clinical symptoms in the early stages. Some patients may show mild systemic symptoms in the early stages, such as weakness, wasting, chronic or intermittent low fever, anorexia, mild anemia, etc. Due to the mildness of the disease, most patients cannot be detected early, resulting in delays and loss of the best time for treatment. The etiology of AS has not been fully elucidated yet, but most of them believe that genetic, infectious and immune environmental factors are related. Genetic factors play an important role in the development of AS. According to epidemiological surveys, the rate of HLA-B27 positivity in AS patients is as high as 90%-96%, while the rate of HLA-B27 positivity in the general population is only 4%-9%; the incidence of AS in HLA-B27 positive patients is about 10%-20%, while the incidence in the general population is 1‰-2‰, a difference of about 100 times. It has been reported that the risk of AS in a group of relatives is 20 to 40 times higher than that of the general population, and the prevalence of AS in first-degree relatives is 24.2% in a domestic survey, which is 120 times higher than that of the normal population. the chance of AS in relatives of HLA-B27-negative healthy people is much lower than that of relatives of HLA-B27-positive AS patients. All these indicate that HLA-B27 is an important factor in the development of AS. However, it should be noted that, on the one hand, not all HLA-B27-positive individuals develop spondyloarthropathy, and on the other hand, approximately 5% to 20% of patients with spondyloarthropathy test negative for HLA-B27, suggesting that other factors besides genetics influence the development of AS. Therefore, HLA-B27 is an important genetic factor in the expression of AS, but it is not the only factor affecting the disease. There are several hypotheses to explain the joint between HLA-B27 and spondyloarthropathies: ①, HLA-B27 acts as a receptor site for an infectious factor; ②, HLA-B27 is an indigenous modification of immune response genes that determines susceptibility to environmental excitatory factors; ③, HLA-B27 can cross-react with foreign antigens, thereby inducing the development of tolerance to foreign antigens; ④, HLA-B27 enhances neutrophil activity [15]. With the help of monoclonal antibodies, cytotoxic lymphocytes, immunoelectrophoresis and restriction fragment length polymorphism, about seven or eight subtypes of HLA-B27 have been identified [1]. There may be genetic differences between healthy individuals positive for HLA-B27 and patients with spondylosis, for example, all HLA-B27 individuals have a constant HLA-B27M1 antigenic determinant cluster and antibodies against this antigenic determinant cluster can cross-react with HLA-B27. Most HLA-B27 molecules also have an M2 antigenic determinant. HLA-B27M2 negative molecules appear to be more strongly associated with AS than other HLA-B27 subtypes, especially in Asians, and HLA-B27M2-positive subtypes may have an increased susceptibility to Reiter syndrome. It has been shown that two antigenic determinants, HLA-B27M1 and M2, and the arthropogenic factors Saurobacter, Shigella, and Narsenia can cross-react. Those with low response seem to show more AS, while those with enhanced response develop reactive arthritis or Reiter’s syndrome. Ebrimger et al. found that the detection rate of Klebsiella pneumoniae in the stool of AS patients was 79%, compared with 20% in controls, and the enhanced slope was >10%/min. (4) Pathological examination of the sacroiliac joint showed inflammation. 3. The diagnosis of AS can be made if clinical criteria 1 and 3 of the other criteria are met, as well as any of the imaging and pathological criteria. Complications 1. Cardiac lesions: Aortic valve lesions are more common, according to the autopsy, about 25% of AS cases have aortic root lesions, and cardiac involvement can be clinically asymptomatic or have obvious manifestations. 2, ocular lesions: long-term with the room, 25% of AS patients have conjunctivitis, iritis, uveitis or uveitis, the latter may occasionally be complicated by spontaneous bleeding in the anterior chamber of the eye. Iriditis is prone to recurrence, with a higher incidence the longer the disease, but is not related to the severity of spondylitis, which is common in those with peripheral arthropathy and may occur in a few cases before spondylitis. Ocular disease is often self-limiting, sometimes requiring treatment with corticosteroids, and in some cases can lead to glaucoma or blindness without proper treatment. Ear lesions: Gamilleri et al. reported that chronic otitis media occurred in 1/2 of 42 patients (29%) with AS, which is 4 times more than normal controls, and that there were significantly more extra-articular AS patients with chronic otitis media than AS patients without chronic otitis media. Pulmonary lesions: A small number of patients with AS may develop irregular fibrotic lesions in the upper lobe of the lung, manifested by coughing, shortness of breath, or even hemoptysis, and may be accompanied by recurrent pneumonia or pleurisy. x-ray examination shows diffuse fibrosis in the upper lobe of the lung bilaterally, and there may be cyst formation and parenchymal destruction, similar to tuberculosis, which needs to be differentiated. 5, neurological lesions: due to spinal ankylosis and osteoporosis, cervical dislocation and spinal fracture can easily occur, causing spinal cord compression; if intervertebral discitis occurs, it can cause severe pain; AS can invade the cauda equina in the late stage and cauda equina syndrome can occur, resulting in lower limb or hip nerve root pain; loss of infection in the sacral nerve distribution area, weakened Achilles tendon reflex and bladder and rectal and other motor dysfunction. 6, amyloidosis: a rare complication of AS. In 35 cases of AS, routine rectal mucosal biopsy revealed amyloid deposits in 3 cases, mostly without specific clinical manifestations. 7, renal and prostate lesions: compared with RA, AS rarely occurs renal impairment, but there are reports of IgAD nephropathy. chronic prostatitis is higher in AS than in the control group, the significance of which is unknown.