Developmental dislocation of the hip (DDH), formerly known as congenital dislocation of the hip (CDH), was renamed by the North American Society for Pediatric Orthopaedic Surgery in 1992 and can also be referred to as developmental dysplasia of the hip (DDH). （The epidemiological investigation of developmental dysplasia of the hip (DDH), in addition to congenital factors, has led to a growing belief that acquired factors play a role in the disease. factors play an important role in the disease. For example, swaddling and nursing habits, breech delivery, and an increase in the proportion of cesarean deliveries. The goal of treatment for developmental dislocation of the hip (DDH) is to achieve a stable concentric reduction and to reduce or avoid ischemic necrosis of the femoral head, postoperative re-dislocation, and hip dysfunction. The more commonly used surgical methods to improve the acetabular condition include salter pelvic osteotomy, pemberton osteotomy, chiarri osteotomy, Ferguson surgery, and the rest are Steel osteotomy and Dega pelvic osteotomy, etc. The following is a brief summary of the main indications of the common surgical methods and the developmental improvements in recent years and the causes of postoperative re-dislocation, so as to provide a better understanding of the clinical treatment of DDH. Conservative treatment: According to Hrris’s law (concentric head and socket is the basic condition for hip development) and the derived method of keeping the hip joint stable in a fixed posture and selecting the most suitable age for hip development, various methods have emerged, the more common ones are pavlik sling method, overhead traction reset method, etc. method, etc. (1) pavlik sling method and other support methods: pavlik sling method is suitable for infants aged 0-6 months with positive ortolani sign and positive barlow sign. 1957 pavlik reported its repositioning mechanism, the principle of which is to rely on the natural repositioning of the pediatric hip joint in flexion, abduction and external rotation, and the repositioning maintains the concentric repositioning of the femoral head, creating conditions for normal acetabular and femoral head development. It creates the conditions for normal development of the acetabulum and femoral head. The advantages are that it is simple, lightweight, easy to grasp, and allows for a certain amount of independent movement of the hip joint, which is beneficial to the development and shaping of the hip joint. In 1987, Dai Xiangqi designed a dressing brace, which not only has the advantages of pavlik brace, but also consists of a sleeveless shirt made of common wiring, a sockliner and a connecting belt, which can bear the pressure evenly, without the disadvantages of extrusion and dislodgement, and can be easily adjusted through grommets. Barlow brace and Rosen brace are commonly used treatment devices abroad, and their repositioning is reliable, but because it is violent repositioning instead of natural repositioning, it is prone to femoral head necrosis, and even occurs on the normal side. (2) Overhead traction repositioning method: It is suitable for those who are under 6 months old, have dislocation degree III or have heavy spastic contraction of the adductor muscle, and have failed to apply pavlik brace, and can also be considered for children over 1 year old, and can be repositioned by horizontal traction – vertical traction – overhead traction – abduction traction. This method is not commonly used in clinical practice. (3) Traction followed by release of the adductor muscle and fixation of the human frog cast: this method is between conservative and surgical treatment, and should belong to the category of conservative treatment. It is suitable for children over 6 months of age and infants under 18 months-2 years of age with less soft tissue filling in the joint capsule and acceptable anterior tilt angle and neck stem angle. However, this method is prone to complications of ischemic necrosis of the femoral head, and care must be taken to review the x-rays. The conservative method of closed reduction with frog cast fixation described in traditional textbooks under the age of 3 weeks is too broad, especially in older children with a high chance of residual deformities such as femoral head necrosis, which has been reported to be as high as 50%-80%. With the in-depth research on DDH, the modern treatment concept has changed a lot compared with the past, the most important point of which is to emphasize early surgical intervention and a new understanding of the success rate of closed repositioning, which is generally considered to be higher before one year of age, and about two-thirds of DDH found in the toddler period will develop residual deformity with conservative treatment, so the age of surgical incision is getting younger and younger, and it is generally advocated that 18 months can be surgery. (4) Residual deformity after conservative treatment: After conservative treatment, many children have no obvious clinical symptoms such as hip discomfort and lameness despite the existence of residual deformity on imaging, which is not easy to attract the attention of parents and doctors. With the growth, weight and activity of the child, in adolescence, the child may have easy fatigue, hip pain and mild lameness, which may be aggravated by long-distance walking or strenuous activities. x-ray indicates that the acetabulum has dysplasia and hip subluxation, which may be progressively aggravated and degenerative changes may appear in early adulthood, seriously affecting the quality of life of the patient. Therefore, children with conservative treatment must be followed up regularly and closely and given appropriate and timely treatment when necessary to prevent early onset of degenerative joint disease and avoid or delay joint replacement, which may be one of the most important treatment tasks in the field of pediatric orthopedics in the future. 2. Surgery (1) Ferguson surgery: For non-surgical failures, children within 1 year of age are usually treated with surgery because of their relatively mild pathological changes. Ferguson surgery is commonly used, and its characteristics are: ① the factors affecting the repositioning can be clearly found ② the joint capsule can be better exposed, and the enlarged glenoid lip, round ligament and transverse acetabular ligament can be easily eliminated after incision; ③ the failure of surgery does not affect the implementation of other surgeries. Disadvantages: (1) the anterior and superior part of the joint capsule cannot be fully exposed, especially the iliac bone adhesions above the acetabulum cannot be stripped; (2) the bony deformity of the acetabulum and upper femur cannot be corrected; (3) the incidence of head necrosis is high due to the high pressure of the femoral head after direct repositioning. (2) Salter osteotomy: It was proposed by Salter in 1961 and is the most widely used operation in clinical practice. At present, the indications for Salter’s pelvic osteotomy are generally accepted in China: children aged 18 months to 6 years. The acetabular ratio is appropriate and the acetabular index is <45°. The advantage is that the acetabular orientation is surgically changed so that the femoral head is covered by the acetabulum both anterolaterally and superiorly. The disadvantage is that it destroys the integrity of the pelvis, is more traumatic, is not easily manipulated, and has an inherent disadvantage for cases with posterior and external superior acetabular rim dysplasia and severe deformation of the femoral head, and is prone to postoperative re-dislocation. < p="">(3) pemberton’s osteotomy (also known as acetabuloplasty and peri-articular capsule iliac osteotomy) is a common pelvic osteotomy orthopedic reconstruction procedure first proposed by Pemberton in 1965 and applied in clinical practice. The top of the acetabulum is pried up to improve the inclination of the acetabulum, so that the acetabulum can fully embrace the femoral head and achieve concentric repositioning of the head and socket, thus restoring the normal form and function of the hip joint. The advantages are: (1) incomplete osteotomy, so the stability of the pelvis is not destroyed. ②Highly targeted, and the effect of improving the defect of the anterior superior edge of the acetabulum is certain. The Y-shaped cartilage is used as the axis to rotate forward and downward and outward, which improves the inclination of the shallow flat socket to the greatest extent and reduces the radius of curvature of the acetabulum, resulting in a significant reduction of the acetabular index. The volume is reduced, the depth is increased, and the degree of accommodation is significantly increased, which is conducive to the concentric repositioning of the cephalic socket and promoting it to enter the normal development process. Pemberton himself believes that since the Y-shaped cartilage closes completely at least around 12 years of age, this procedure is suitable for children aged 1-12 years. ④ The means of maintaining the osteotomy and hip repositioning are simple and reliable. If we apply bone graft + hip herringbone cast fixation, we can use less or even no internal fixation and avoid the surgical injury of removing the internal fixation twice. However, its disadvantage is that it requires high operating skills and has poor effect on the correction of resting hip with poorly developed posterior edge of acetabulum and severe mismatch of head and socket. Compared with Salter osteotomy, the formed acetabulum is easily absorbed and the pressure on the femoral head epiphysis is significantly increased by the distal downward pressure of the acetabulum at the distal end of the osteotomy, which is easily complicated by aseptic necrosis of the femoral head. (4) Chiari internal pelvic displacement osteotomy: Chiari internal pelvic displacement osteotomy can correct the pathological lateral displacement of the femoral head, bring the internal displacement of the hip closer to the midline, and improve the biomechanical properties. As the distal pelvis of the osteotomy is internally displaced, the load is distributed over a larger area of the socket, and the length of the abductor lever arm is shortened, reducing the abductor pull and effectively increasing the weight-bearing area at the top of the acetabulum, thus reducing the pressure on the femoral head and facilitating the shaping of the acetabulum and femoral head. Early surgery is necessary when the first pain is experienced by the child, and the results deteriorate with age. The outcome is worse in those with severe preoperative osteoarthritis and hip range of motion <90°. The osteotomy block must provide a complete coverage of the femoral head, which is an important factor in the long-term outcome. Intra-articular osteotomies can lead to ischemic necrosis of the femoral head and should be avoided. In patients with existing osteoarthritis, Chiari osteotomy can create a good acetabulum for subsequent total hip surgery. Due to the age of the child undergoing the Chiari internal pelvic osteotomy, osteoarthritis cannot be significantly avoided and is not as effective as the salter pelvic osteotomy in terms of long-term pain relief and promotion of acetabular development. Although chiari pelvic osteotomy is suitable for most older children with DDH, it is only a palliative procedure to treat DDH and should not be used as the first choice. (5) The rest of various procedures: ①Dega osteotomy: Although Dega pelvic osteotomy is similar to Pemberton osteotomy and is an incomplete osteotomy of the pelvis, its osteotomy only truncates the part of the iliac bone above the Y-shaped cartilage line (iliac situs and iliac pubic bone), and the cortices of the posterior internal and external plates of the iliac bone in front of the situs notch are not truncated to form a hinge to correct the morphology and direction of the acetabulum to improve the The acetabular index and CE angle were improved and the femoral head coverage was improved. The age of the operation can be relaxed because the acetabulum is turned down through an incomplete fracture of the iliac bone without considering the closure of the Y-shaped cartilage. This procedure is simple and minimally invasive, and it does not affect the shape of the pelvis or subsequent delivery in female children. It also does not cause damage to the Y-shaped cartilage of the acetabulum because it is performed under direct vision. This surgical method can improve the anterior, lateral and posterior coverage of the acetabulum, with wider indications and less surgical trauma. ②Steel osteotomy: The three osteotomies performed by Steel, in which the sciatic bone, pubic bone and the iliac bone above the acetabulum are truncated, the acetabulum is reoriented, and stabilization is obtained by fixation with bone graft blocks and kyphotic pins. The goal of the procedure is to create a more anatomically stable hip joint for hip dislocation or subluxation in older children who cannot be treated with other osteotomies. (iii) Ganz osteotomy: Ganz et al. developed a three-plane periacetabular osteotomy to treat hip dysplasia in adolescents and adults requiring correction of hip mismatch and increased coverage of the femoral head. Advantages include the ability to achieve substantial correction in several directions, preservation of acetabular blood flow, and preservation of the stability of the posterior lateral column of the hemipelvis. Westin joint pelvic osteotomy: Starting between the anterior and superior iliac spines, the osteotomy is extended in an arc along the superior edge of the joint capsule attachment point to the posterior inferior acetabulum, and then changes direction when it reaches the proximal end of the sciatic body in the posterior inferior acetabulum, i.e., a longitudinal osteotomy of the sciatic body along the frontal plane distally, ending 1.5 cm below the sciatic spine. The distal end of the osteotomy was rotated outward and downward together with the acetabulum, and the change in the direction and volume of the acetabulum was observed. After rotation to the desired angle, a triangular bone cut from the anterior superior iliac spine is inserted into the osteotomy gap to maintain the position of the distal end of the osteotomy and to facilitate healing of the osteotomy. The indications are a, age >6 years; b, superficial and lateral acetabular wall defects, acetabular index >45°; c, femoral head matching the size of the acetabulum. However, a severe posterior lateral defect of the acetabulum and a mismatch between the head and socket of the femoral head whose diameter is significantly larger than that of the acetabulum should be considered as contraindications to this surgery.3. About additional subtrochanteric osteotomy Subtrochanteric osteotomy is often performed simultaneously with incisional repositioning or pelvic osteotomy, etc., as an adjunct to the above-mentioned surgery. The shortening of the upper end of the femur can effectively overcome the tension of soft tissues, especially the adductor muscle, and reduce the pressure on the femoral head after repositioning, which is required to achieve tension-free repositioning during the operation, thus reducing the rate of femoral head necrosis. Rotational osteotomy corrects the anteversion angle and neck stem angle. With regard to the fixation of the femoral head after osteotomy, Sun Jun’s use of a right-angle plate has solved the problem of synergistic correction of the cervical stem angle and the anterior tilt angle, which is worth promoting on a large scale compared with the need for pre-bending before fixation of a straight plate and the tendency to complicate “breeches deformity”. 4. The common complications are: ischemic necrosis of the femoral head, postoperative dislocation and joint stiffness. (1) Ischemic necrosis of the femoral head: This is a medical complication, mainly due to mechanical pressure causing arterial ischemia. It is commonly caused by frog fixation in conservative therapy, excessive intra-articular soft tissue filling, inadequate preoperative traction for high dislocation position, uncircumcised adductor muscle, and inadequate osteotomy for femoral shortening. (2) Re-dislocation: The causes of re-dislocation after manual repositioning include excessive acetabular index (>45°), excessive anterior tilt of femoral neck, inadequate traction before repositioning, high dislocation with gourd-shaped joint capsule, narrow middle, embedded between femoral head and acetabulum, small and flat femoral head, short femoral neck development, etc. The causes of re-dislocation after surgical incision and repositioning include inappropriate selection of surgical indications (e.g., a child was 5 years old with an acetabular index of 50° and selected salter pelvic osteotomy, which resulted in re-dislocation when the child was 6 years old), too large or too small correction of the anterior tilt angle during surgery, too high position of the acetabular lid, bone resorption, small amount of bone graft or insufficient height of bone graft, improper treatment of the joint capsule, loose sutures, etc. (3) Hip stiffness: the older the age, the higher the incidence, the higher the dislocation, and the more severe contracture around the hip joint, which is very likely to occur if not corrected, especially for those with postoperative hip herringbone cast fixation. The early postoperative joint functional exercise should be strengthened, which can also be carried out with the help of CPM machine. 5. In conclusion, the treatment of pediatric developmental hip dislocation is systematic and complex, and should be based on the child’s own conditions, taking into account various factors such as age, femoral development and acetabular development, to choose the personalized treatment plan that best fits the child’s condition. With the in-depth research on DDH, the modern treatment concept has changed a lot compared with the past, the most important point of which is to emphasize early surgical intervention and a new understanding of the success rate of closed repositioning, which is generally considered to be higher before the age of one year, and about two-thirds of DDH found in the toddler period will have residual deformity with conservative treatment, so the age of surgical incision is getting younger and younger, and it is generally advocated that it can be performed at 18 months Surgery, according to a large number of clinical summaries, the optimal age for surgery should be around two years old. Among the above surgical treatment options, salter’s osteotomy is the most classic, and Pemberton’s osteotomy is also widely used. generally speaking, no matter which pelvic osteotomy is chosen, it is often necessary to attach a short inversion rotational osteotomy of the proximal femur in order to achieve a more ideal treatment effect. 6. references (omitted)