Developmental dislocation of the hip (DDH) in children was originally called congenital dislocation of the hip. Some scholars reported that some newborns with normal clinical and radiographic examinations developed hip dislocation later, so the name was changed to “developmental dislocation of the hip”, which is still used today. Developmental hip dislocation includes acetabular dysplasia, femoral head subluxation and complete dislocation of the femoral head, with a prevalence of 3.8 per 1,000 in China. The incidence of breech birth is 5 times higher than that of normal birth, 4 times higher in women than in men, and 7 times higher in those with family history. The left hip is more involved than the right hip, and bilateral hip dislocation is higher than right hip dislocation. The etiology is unknown, including mechanical theory, hormonal theory (causing joint laxity), primary acetabular dysplasia, and genetic theory. Infants with a history of swaddling may increase its incidence. Diagnostic points In the neonatal period (from birth to 6 months), asymmetry of the thigh skin folds, positive bilateral hip abduction test, positive ultrasound, positive Ortolani test and Barlow test. From 6 to 18 months of age, asymmetry of the skin folds of the thighs, positive hip abduction test, positive Alli’s sign, and hip dislocation on radiographs. At the age of walking, lower limb limp, bilaterally dislocated gait wobble, also known as “duck gait”, superior displacement of the greater trochanter, positive Trendelenburg’s sign, positive Alli’s sign. x-ray examination is helpful for diagnosis and treatment, Shenton’s line and Calve’s line show interruption, Hilgenreiner’s horizontal line and Perkins’ vertical line, which are used to determine the location of the dislocated femoral head. The acetabular index and CE angle are measured for signs of acetabular dysplasia and defects (Figure 1). three CT reconstructions help to visualize the bony pathological changes and the choice of surgical procedure. Conservative treatment: In the neonatal period (from birth to 6 months), children with positive Ortolani and Barlow tests can be treated with closed repositioning and a Pavlik harness with a success rate of 85% to 95%; children with negative Ortolani and Barlow tests should not be treated. In infants (6 to 18 months of age), children with subluxation and total dislocation with joint laxity can be treated with closed repositioning, plaster or brace fixation on a trial basis. Surgical treatment More than 6000 cases of DDH were treated surgically, and the excellent rate increased to 98.2%. We have learned that any form of treatment, including conservative treatment and surgery, is not recommended for children with DDH in infancy and early childhood before the nucleus pulposus has emerged, otherwise ischemic necrosis of the femoral head is likely to occur. We advocate the concept of individualized surgical treatment, based on a comprehensive understanding of various types of pelvic osteotomies, and select the appropriate surgical procedure according to the characteristics of the bony pathology of the child, combining proximal femoral (shortening p inversion p rotation) osteotomy in one phase to achieve central repositioning. In older children with DDH, we found that the acetabulum has different degrees of acetabular defects, and all kinds of pelvic osteotomies are designed to change the direction of the acetabulum, which cannot repair the acetabular defects, and the repair of acetabular defects with sutures muscle flap reversal and displacement for hip dislocation can effectively solve this problem. For children over 18 months of age, once the diagnosis is confirmed, they should be treated with an incisional repositioning and pelvic osteotomy combined with proximal femoral osteotomy. There are several ways of pelvic osteotomy, and the treatment should be individualized according to the characteristics of the pathological changes. Ischemic necrosis of the femoral head is a catastrophic complication after hip dislocation treatment. Children whose femoral epiphyseal nucleus has not appeared are prohibited from any form of treatment, which can effectively prevent the occurrence of femoral head necrosis. The proximal femoral shortening osteotomy pair can greatly reduce the incidence of postoperative femoral head necrosis. Postoperative dislocation of the femoral head: individualized selection of pelvic osteotomy combined with inversion rotation osteotomy of the proximal femur p correction of the anterior femoral neck angle and neck stem angle is an effective means to prevent re-dislocation, and thorough cleaning of the true socket to reveal and joint capsule shaping is an important aspect that should not be careless. Postoperative joint stiffness: Intraoperative delicate operation, reduction of trauma and bleeding, and early postoperative systematic rehabilitation can effectively prevent and treat postoperative joint stiffness.