Congenital hip dislocation (also known as developmental hip dislocation) is the most common congenital deformity of the lower extremities in children, and its incidence varies from region to region. It is more common in girls than in boys, and the ratio of men to women is about 1:5. It can occur bilaterally, unilaterally about twice as often as bilaterally, and more often on the left than on the right, with a ratio of 2:1. The real cause of this disease is still not very clear, but after years of research by medical workers, it is thought to be related to the following factors: mechanical factors of malposition in the uterus, genetic factors, ligament laxity, endocrine factors, postnatal environmental factors (such as the method of holding the newborn baby), and the customary way of holding the newborn baby in the northern part of China. (The incidence is higher in the northern part of China because of the habit of wrapping newborns with both hips in an upright position.) The incidence is higher. The main pathological changes of congenital hip dislocation are the loss of the normal correspondence between the femoral head and the acetabulum, poor development of the femoral head and acetabulum, shallowing of the acetabulum, filling of the acetabulum with fibrofatty tissue, and special relaxation and thickening of the joint capsule. Because the cause of this disease has not been determined, there is not yet a reliable and effective method to prevent the occurrence of this disease, and only early detection and early treatment of this disease can achieve good treatment results. For early detection, it is important to understand the signs and symptoms of the disease. 1. Bilateral asymmetry of the thigh skin pattern and perineum, with the affected side of the buttocks more prominent. 2. The mobility of both lower limbs is different in newborns, and the affected side is not active. 3.Walking is late and the gait is abnormal. Normal children usually start to walk at the age of 1-1.5 years, but most of those with dislocation learn to walk only at the age of 1.5 years, and the walking gait is abnormal, with a limp gait in unilateral dislocation and a swaying gait in bilateral dislocation. 4. Restricted hip abduction and positive frog leg test. 5.Bilateral limbs are not equal in length, the affected side is shorter than the healthy side, the hip and knee are flexed bilaterally, and the two knees are not equal in height when the two feet are aligned. The disease should be treated promptly after discovery, and the treatment is divided into two kinds of conservative treatment and surgical treatment. Generally, for those under 6 months old, the Pavlic sling is used for fixation, and for those 6 months-1.5 years old, conservative treatment is used, that is, after traction, reset plaster fixation under general anesthesia, and later brace fixation is used, which takes 9-10 months. For those who are older than 1.5 years old, they are mostly treated by surgical methods, and there are more surgical methods, and different surgical methods are used according to different conditions.