Ankylosing spondylitis (AS) is a systemic disease involving multiple organs throughout the body, with a familial tendency and an incidence of about 1.5%. There are two types of primary and secondary conditions: primary ankylosing spondylitis generally develops at the age of 10-20 years, with a peak of 30-40 years; secondary ankylosing spondylitis can occur at any age. In earlier years, the incidence of the disease was thought to be more common in men than in women, about 10:1, but in recent years studies have found no significant difference in the incidence of the disease by gender. Male patients more often present with progressive spinal lesions and hip lesions. In women, peripheral joint involvement is more common, and the clinical symptoms are mild and easily confused with other diseases, so the patients seen in the clinic are usually men with “waist failure before old age”, bending over, flexing the hips, extending the buttocks back, and having a dull facial expression, which is very characteristic and can often be seen at a glance. At this time, the HLA-B27 test is just a process, because the sacroiliac joint has already fused and a bone bridge has appeared between the lumbar vertebrae. Since this disease is characterized by the phenomenon of “terminal inflammation of the tendon”, the soft tissues around the joint are extensively involved and are prone to heterotopic ossification. In this patient, the muscle fibrosis is obvious, like a rope, and does not bleed easily when cut. This is distinctly different from the muscle changes seen in rheumatoid arthritis. In ankylosing spondylitis, the patient is young, active, and has limited lumbar spine movement, all of which increases the amount of mechanical movement of the hip joint and increases wear and tear, so these patients often have severe wear and tear of the femoral head at a very young age, necrosis, and ankylosis of the hip joint, which results in a flexion deformity of the hip joint (fibrous or bony stiffness of the joint), and the patient is unable to see eye level. Standing and walking are abnormally difficult. Patients may have been seeing an immunologist at this point, hoping that internal medication would solve the problem, and often only consult an osteoarthrodiologist when the disease has progressed to an unusually severe level. There is only one path left to take with joint replacement. So to those with ankylosing spondylitis: love your joints, love your hips. I have operated on a number of people with ankylosing spondylitis who have bilateral hip arthropathy. When the patient came to the hip joint is strong in the flexion position, can not sit straight, lying flat, young face, little old man’s hunched body. Bedridden at home for many years, bringing a heavy burden to the whole family. These patients are usually male patients, over 35 years old, whose wives and siblings take care of him all year round, with early hair, full of fatigue and sadness, dragging several families who cannot live normally. The patient is also under great pressure and even has thoughts of not being able to live. They cannot take care of themselves and are suffering. For such patients, bilateral surgery can be performed at the same time, which not only saves money but also greatly reduces the patient’s pain, and the patient can sit up straight and lie down the day after surgery. The recovery of the patient’s body helps not only himself but also the family. Of course, as a doctor, this is part of the philosophy of mercy.