The treatment of pediatric congenital hip dislocation, i.e. pediatric developmental hip dislocation, is systematic and complex, and should be based on the child’s own conditions, taking into account a variety of factors, such as age, femoral development, acetabular development, etc., and choosing a personalized treatment plan that is most suitable for the child’s condition. With the in-depth study of DDH, the modern treatment concept has changed a lot compared with the past. 1. Acetabular dysplasia: also known as unstable hip. Early asymptomatic, a high percentage of postnatal present hip instability, often characterized by an increase in acetabular index on X-ray, and gradually stabilized with growth and development. If the appropriate hip joint external table is used, it will be cured by itself; a small number of persistent acetabular dysplasia changes, symptoms appear after growing up, and surgical treatment is needed. 2.Hip subluxation: the femoral head and acetabulum are poorly developed, the femoral head is shifted outward and upward, but not completely detached from the acetabulum, X-ray can see that the femoral head is shifted outward, the acetabular index increases to more than 35 °, but the head of the femur can be touched in front of the groin. Hip subluxation is neither a result of acetabular dysplasia nor a transitional stage of hip dislocation, but an independent type that can exist for a long time. 3, Hip dislocation: this type is the most common, the femoral head has been obviously detached from the acetabulum, and outward and upward displacement, the labrum is embedded in the joint in the arthrography, so that the acetabulum is isolated from the femoral head and the femoral head can’t enter into the acetabulum, and with the increase of age, there are a lot of secondary changes, which makes the treatment more difficult. There are three degrees of dislocation of the femoral head according to the level of dislocation. Although the femoral head is dislocated to the outer side, it is located at the same level of the acetabulum as degree I; the femoral head is dislocated to the outer and upper side, which is equivalent to the level of the outer upper rim of the acetabulum as degree II; the femoral head is completely dislocated to the upper side of the posterior and posterior side and is located in the wing of the ilium as degree III; some scholars propose that for the femoral head dislocation of the high level, up to the level of the sacroiliac joints, it should be classified as degree IV. Clinical examination: If every newborn can be examined routinely after birth, and the diagnosis is clear and treatment is carried out within 3~7 days, the therapeutic effect is the most ideal; if the diagnosis is clear and the treatment is successful within 1 year old, and the X-ray examination can be completely normal in the future, which illustrates the importance of early diagnosis and treatment. Careful clinical examination is particularly important in the neonatal period and in young infants (from birth to 6 months). Routine clinical examinations include the Ortolani test and the Barlow test. The Ortolani test involves gentle abduction and adduction of the hip in hip flexion to check for incorporation and dislocation of the femoral head. In children with hip dislocation, when the hip joint is abducted or adducted to a certain degree, and the femoral head is incorporated into or dislodged from the acetabulum, the hip joint pops, i.e., the Ortolani test is positive, and it is one of the most reliable signs for diagnosing developmental hip dislocation. The Barlow test is a positive test if axial pressure is applied when the hip joint is flexed and adducted, and if the femoral head is felt to be dislocated backward, and then returns to its original position after the pressure is removed. This test confirms hip dysplasia or hip instability with potential subluxation or posterior dislocation. In hip dislocation, the thigh is disproportionate to the calf, the hip is wide, and the groin crease is asymmetrical, short or absent on the affected side. The gluteal dermatomes are also different, with an elevated or an extra strip on the affected side, and the entire lower extremity is shortened in a mild externally rotated position. This skinfold asymmetry is usually only a sign that requires further examination. Normal infants can have asymmetrical skin tags, and children with hip dislocation can also have symmetrical skin tags. As a result of hip dislocation, the femoral artery loses its sillage to the femoral head and beats significantly less. When the child is between 6 and 18 months old, there are some changes in the clinical presentation. For example, the femoral head has dislocated from the acetabulum, and it is no longer possible to incorporate the femoral head into the acetabulum by simply abducting the hip. A number of other clinical signs become more apparent, the first and most reliable being the restriction of abduction of the dislocated hip due to contracture of the adductor muscle group. The infant is placed flat on the examination table, the knee is flexed and the hip is flexed 90° each, the examiner faces the child’s buttocks, both hands hold the child’s knees and abduct them simultaneously, the normal knee lateral surface can touch the table surface, and the affected side can only reach 75~80° in dislocation, which is called a positive hip abduction test. However, in cases of hip dislocation, there may be no limitation of abduction, and in infants and children with normal hips, there may be a limitation of hip abduction. When the femoral head dislocates not only laterally, but also upward, causing relative shortening of the femur on the side of the dislocation, this is characterized by a positive Allis sign or a positive Galeazzi sign. Due to dislocation of one side of the hip, the child lies flat on the ground, bends the knee at 85-90°, puts both feet flat on the table, and the two ankles are close together to see that the height of the two knees is not equal. In children of walking age, lameness is often the only complaint of the child at the clinic. One side of the dislocation limp, bilateral dislocation performance “duck step” posture, buttocks obviously protruding back, gait wobble. After hip dislocation, the femoral head loses its fixed position in the acetabulum and rises to the side of the pelvis, which results in involvement of the gluteus medius muscle and weakening of the muscle strength, which is manifested by a positive Trendelenburg test. The line from the anterior superior iliac spine to the sciatic tuberosity normally passes through the apex of the greater trochanter called Nelaton’s line, and the greater trochanter is above this line in dislocation. Ultrasound hip joint examination technology to diagnose developmental hip dislocation has been carried out in many countries and regions around the world, which promotes the early detection and early treatment of developmental hip dislocation, and effectively reduces the late incidence of the disease and the incidence of complications. Ultrasound has the property of penetrating cartilage without the damage of rays, which is especially suitable for examination in newborns and infants whose femoral head has not yet ossified, and it has become the preferred method to replace X-ray for the diagnosis of developmental hip dysplasia and assessment of the efficacy of treatment in newborns and infants. As the ossification center of the femoral head forms and enlarges, the ability of ultrasound to penetrate the femoral head is obscured and its ability to visualize the acetabular base decreases. In general, ultrasound is no longer appropriate to examine the hip in infants older than 6 months of age. There are two types of ultrasound hip examinations: static and dynamic.Graf’s static examination and classification method is the most widely used method and classification. The representative of dynamic examination is Harcke, which is mainly applicable to the neonatal period, but the popularity is far less than the former.Graf method requires that the straight ilium, rounded bony acetabular roof and cartilaginous acetabular roof must be seen on the standard image; and measure the angle α of the ilium as the baseline of the acoustic shadow with the bony acetabular roof and the angle β with the cartilaginous acetabular roof, and according to the angle of α and β, categorize the examined hip joints into four types. Type.