Pediatric Perthes disease, also known as ischemic or aseptic necrosis of the femoral head, is a self-healing, self-limiting deformity that occurs locally in the femoral head in children and is not a systemic disease. The goal of treatment of Perthes disease in children is to prevent complications during the repair period, which are commonly associated with femoral head epiphyseal deformity, subluxation, and premature closure of the epiphyseal plate. Since the etiology of pediatric Perthes disease has not been determined, there is no specific treatment method. The concept of “containment” of Perthes disease in children was first reported by Parke, Eyre-Brock (1936,1966), and later further elucidated and applied by Harrison (1966) and Salter (1966,1980). It was further elucidated and applied by scholars such as Harrison (1966) and Salter (1966,1980). The pathological process of this disease is mainly osteoclast death, followed by osteonecrosis, revascularization and reossification, and finally femoral head repair and quiescence. After osteonecrosis, revascularization begins and reossification occurs immediately afterwards. New bone is deposited in layers on the necrotic trabeculae, and the new bone initially formed is symphyseal and plastic. At this stage, the shear stresses acting on the femoral head combined with bone resorption can lead to subchondral fractures of the original symphyseal bone in the subchondral region. The subchondral fracture gradually undergoes bone resorption and is replaced by vascularized fibrous tissue, which is then replaced by the original symphyseal bone, which is then replaced by lamellar bone, a process Salter calls “biological plasticity”. If the femoral head is “biologically plastic” with good acetabular “accommodation”, the femoral head will recover optimally; if there is no good “accommodation”, the pressure on the femoral head will be uneven and the femoral head will be prone to deformation. If there is no good “accommodation” and the pressure on the femoral head is not uniform, the femoral head will easily become deformed, flattened or irregular, and the acetabulum will change accordingly. This is the rationale for “inclusive” weight-bearing therapy, which has now replaced the weight-restricting therapy of the past. Since the etiology of Perthes’ disease is undetermined, the course of the disease is long, and the pathology and x-ray manifestations are complex, there are many treatment methods. Because the prognosis of this disease cannot be clearly determined in a short period of time, aggressive treatment should be given regardless of age, and the best results are achieved when the femoral head is not significantly deformed. All treatments should be performed before the disease progresses to such an extent, with the aim of stopping the development of deformities in the femoral head. The indications for non-surgical treatment include: (1) the child is young, under 6 years old; (2) the lesion only involves the anterolateral part of the epiphysis or the lateral column compression is less than 50%, or the contour of the femoral head is still round; (3) Catterall type I and II or Herring type A and B; (4) there is no obvious “head crisis” sign. (3) Catterall type I, II or Herring type A and B; (4) no obvious “head crisis” sign. Non-surgical inclusion treatment is to make the child abduct and internally rotate the hip joint under weight, and place the femoral head in the acetabulum, which can cover the entire femoral head epiphysis, with the lateral epiphyseal plate located at the socket edge, so that the head and socket are concentric circles, and the joint contact surface is uniform and the pressure is balanced, preventing the gravity from concentrating in one place and dispersing on the entire joint surface, which is conducive to the “biological shaping” of the femoral head “This helps to maintain the roundness of the head. The most commonly used non-surgical inclusion therapy is the use of the Atlanta Scottish Rites abduction brace, which allows free movement of the knee and ankle joints after wearing the brace and is easily accepted by the child. As long as the femoral head is deeply placed in the acetabulum, the pediatrician has sufficient time and remodeling ability to reshape the femoral head in a concentric circle. The brace is usually worn for 6 to 18 months until x-rays show that the lesion has reached the ossification stage. Alternatively, a Petrie long-leg abduction and internal rotation cast can be used for both lower extremities, with the hip placed at 40°-45° of abduction and 10°-15° of internal rotation, allowing the child to walk with the cast, which also provides optimal coverage of the femoral head and facilitates the “bioplasty” of the femoral head. The excellent rate of weight-bearing treatment with non-surgical inclusion can reach 90%, while the excellent rate of non-weight-bearing treatment with long-term bed rest is 60%, and the long-term non-weight-bearing of the affected hip will lead to osteoporosis and impair the function of joint movement. This shows that the effect of weight-bearing treatment is better than that of non-weight-bearing treatment. The indications for surgical treatment include: (1) age over 6 years old; (2) clinical risk symbols, i.e., progressive and persistent joint pain and activity limitation in the affected hip; (3) femoral head involvement up to Catterall type III, IV or Herring type C; (4) subluxation of the hip joint, etc. The “danger sign” of femoral head necrosis is not the basis for choosing surgery, and should not prompt us to adopt traumatic surgical measures, because major surgery not only aggravates the ischemia of the upper femur, but also lacks the rationality of choosing surgical indications. Therefore, we should choose a reasonable surgical approach based on the age and radiographic manifestations of the child, and it is advisable to keep it simple rather than complicated, and we should discard highly invasive and complex surgical approaches. There are many surgical options for the treatment of Perthes’ disease in children, such as bone drilling, tipped muscle grafting, vascularized bone grafting, femoral head decompression and synovectomy, etc. However, based on the Salter’s bioplasty theory, the commonly used “inclusive” procedures at home and abroad are pelvic osteotomy (Salter’s osteotomy and Chiari’s osteotomy) and pelvic osteotomy (Chiari’s osteotomy). Chiari osteotomy) and superior femoral inversion osteotomy. The advantages of surgical inclusion therapy are that the treatment time can be shortened, and the patient can walk on the ground and resume normal activities 3 months after surgery, which is conducive to the shaping of the femoral head, and the inclusion of the head is permanent. (i) Salter pelvic osteotomy The indications for Salter pelvic osteotomy are: (i) those who are under 6~7 years old; (ii) those who have Catterall type III, IV or Herring type C epiphyseal necrosis; (iii) those who have signs of subluxation; Salter proposed the doctrine of bioplasty and pointed out that Perthes disease can be treated by iliac osteotomy. Salter pelvic osteotomy can change the orientation of the acetabulum and increase the anterolateral inclusion of the femoral head, so that the femoral head can be placed deep in the acetabulum to achieve optimal coverage, which is conducive to the optimal shaping of the femoral head under concentric inclusion; in addition, Salter pelvic osteotomy can improve the gait and correct the uneven length of the lower limbs due to muscle contracture. The anterolateral aspect of the joint capsule is exposed and the capsule is resected approximately 2.0 x 1.0 cm, which serves as a window for joint decompression. It is also possible to simultaneously reduce the pressure within the femoral head through rotor bone drilling to stimulate the epiphyseal plate and promote healing of the femoral head. After surgery, the hip is fixed in a herringbone cast so that the hip joint is abducted 40°~45° and internally rotated 10°~15°. The cast is fixed for 3 months and can be removed for weight-bearing walking. (2) Chiari pelvic osteotomy Indications for Chiari pelvic osteotomy: ① Age above 7 years old; ② Catterall type III, IV or Herring type C; ③ enlarged and flattened femoral head, mushroom-shaped deformation; ④ poor acetabular coverage and signs of subluxation. The treatment mechanism of Chiari pelvic osteotomy: ①Increase the acetabular inclusion of the femoral head, try to restore the concentric anatomical relationship of the head and socket, so that the necrotic femoral head, all included in the acetabulum, through the normal facsimile, development, to create the physiological conditions for its repair. Chiari osteotomy increases the coverage of the acetabulum on the femoral head with the help of the proximal osteotomy surface, so that the area of the femoral head under pressure becomes larger, thus making the pressure per unit area (pressure) smaller, and the whole femoral head is under pressure on average, so that the necrotic area is no longer under excessive pressure, which is conducive to the repair of the femoral head. repair, and gradually achieve normal contouring in the acetabulum. (3) After Chiari osteotomy, the proximal osteotomy surface can be repaired close to the normal acetabulum with the support of the joint capsule and the femoral head, i.e. Chiari osteotomy is a kind of joint capsule arthroplasty. By enlarging the acetabulum and ensuring that it accommodates the femoral head, this procedure ensures that the femoral head is properly shaped by the biomechanical action of the acetabulum during the shaping period, restoring a round ball shape that matches the acetabulum and avoiding the occurrence of double-headed deformity and subluxation. The osteotomy site must be strictly controlled during the surgery, and the osteotomy must be performed at the true bony acetabular rim with a bone knife at an angle of 10°~15° from the lower part of the anterior superior iliac spine to the sciatic notch in an arc, so as to conform to the physiological curvature of the acetabulum as much as possible on the one hand, and to avoid forward and backward displacement of the distal end of the osteotomy on the other hand, so as to avoid injury to the sciatic nerve. During the operation, a small strip of joint capsule was also removed and decompression was performed by incision or bone drilling at the same time. After the operation, the hip herringbone cast was fixed at 40°~45° of abduction and 10°~15° of internal rotation for 3 months, and functional exercises were performed after the cast was removed, and the hip was gradually put on the ground and walked with weight. （The indications for internal osteotomy of the upper end of the femur are: (1) Catterall type III, IV or Herring type C; (2) subluxation of the femoral head; (3) large neck stem angle or excessive anterior tilt angle. The mechanism of superior femoral inversion osteotomy for Perthes’ disease: ①The anterolateral part of the affected femoral head can be placed in the acetabulum to increase the inclusion of the femoral head in the acetabulum, and good coverage can provide the best “biomorphic” repair of the femoral head. ②When the hip joint is under weight, the pressure on the anterior upper part of the femoral head epiphysis is the greatest, and the internal rotation osteotomy changes the stress point of the femoral head. ③Osteotomy can reduce the intraosseous pressure to eliminate the pain of the affected hip and facilitate the resorption of the necrotic femoral head and the growth and repair of new bone. ④The excessive anteversion angle can be corrected by rotational osteotomy at the same time to further increase the inclusion of the femoral head and restore the concentric circle relationship between the femoral head and the acetabulum. Back in the 1950s, Souer and Somerville reported the application of proximal femoral inversion and rotational osteotomy for this condition. For any superior femoral osteotomy, the preoperative design of the osteotomy site and the desired angle should be strictly designed, usually 10° to 20° of internal rotation and 10° to 25° of rotation. Different surgical approaches can be used depending on the severity of the femoral head lesion. The most ideal osteotomy site for the upper end of the femur is the subrotor or inter-rotor osteotomy. After osteotomy at the subrotor or inter-rotor level, the proximal end is turned inward and the distal end is turned inward and reversed, forming an inward, abducted, and reversed osteotomy, and then fixed with a roughened plate or a 6-hole plate screw. This procedure is suitable for those with obvious subluxation and Shenton’s line (+). However, the inversion osteotomy of the upper femur may result in a small neck stem angle, shortened limb deformity, and gluteus medius weakness complications. The angle of internal rotation osteotomy should be calculated before surgery, and the angle of internal rotation should not exceed 20°, and the neck stem angle should not be less than 110° after osteotomy, otherwise the internal rotation angle may be too large, weakening the abductor muscle strength and making the gluteus medius gait (Trendelenburg sign) more obvious. Prognosis Because the cause of Perthes disease in children is unknown, the age of onset is between 2 and 14 years, the course of the disease is long, and the radiographic manifestations are complex, the correct assessment of its prognosis is a very complex issue, and there is no uniform method to predict the regression or prognosis of the disease. The correct assessment of prognosis is helpful for clinicians to choose treatment rationally. The following factors affect the prognosis of children: ① Age of onset: Age is the most important factor in determining the prognosis of the disease, and the younger the age, the better the prognosis. The younger the age, the better the prognosis. The femoral head loses its ability to reshape only after the epiphysis closes, so the younger the child, the longer it takes for the femoral head to reshape, and the greater the likelihood that the femoral head will acquire good form and function. Most scholars believe that those younger than 6 years old have a good prognosis, while those between 6 and 8 years old have a “gray area” and those older than 8 years old have a poor prognosis. Gender: The prognosis of girls is worse than that of boys, which is related to the early age of bone maturity of girls and the relatively lower remodeling potential of the femoral head. (③) Extent and degree of necrosis of the femoral head lesion: the more severe the extent and degree of femoral head involvement, the worse the prognosis. In particular, the degree of collapse of the involved lateral column of the femoral head is of great value in assessing the prognosis. ④ Inclusion of the femoral head: mutual stimulation between the femoral head and the acetabulum is an important factor in the development of both, and concentric inclusion of both is necessary for good femoral head shaping. Therefore, hip subluxation is an important indication of poor prognosis and must be detected early and treated actively to avoid head and socket deformity. Joseph et al. showed through statistical analysis of 97 cases of children with Perthes disease treated with inclusion surgery that the timing of surgery is an important factor affecting the prognosis, and suggested that children with Perthes disease should be treated with inclusion surgery as early as possible, and once the femoral head is severely fragmented and the new bone is subjected to deforming stress, inclusion surgery cannot prevent the femoral head from Once the femoral head is severely fragmented and the new bone is subjected to deformation stress, further inclusion surgery cannot prevent the femoral head from deformation. (6) Long-term follow-up results suggest that the prognosis of this disease is poor without inclusion treatment. The disease regression is mostly osteoarthrosis of the hip after the age of 50 years, and 50% of them require arthroplasty. In recent years, the Perthes Disease Collaborative Group of the North American Pediatric Orthopaedic Society has conducted a multicenter, prospective study of the treatment of this disease, which showed that inclusion therapy is superior to no treatment, surgical inclusion is superior to abduction bracing, and there is no significant difference between pelvic osteotomy and superior femoral osteotomy. Therefore, aggressive surgical inclusion therapy should be given to those with an age of onset greater than 6 years, femoral involvement up to Catterall type III or IV or Herring type C, as well as femoral deformity, asymmetrical head and socket, or signs of subluxation.