Also known as congenital hip entropion, it is one of the causes of lameness in children and has a low clinical incidence. It was first named hip entropion deformity by Hofmeister, which is mainly caused by abnormal development of the proximal femur resulting in reduced neck stem angle and shortening of the femur on the affected side, resulting in lameness and abnormal appearance. Etiology: The specific cause and detailed mechanism of the pathogenesis are not yet completely clear. The preliminary accepted view is that: in infancy, due to the faster growth of the medial epiphyseal plate of the femoral neck, the nuchal trunk angle can be larger than that in adults, such as up to 150° in 3-week-old infants, and as age increases, the growth of the lateral epiphyseal plate is significantly accelerated, thus making the nuchal trunk angle smaller, and if some factors during development interfere with the normal physiological process, such as changes in the line of force of the body and changes in the negative focus, they can Some scholars have also proposed local aseptic necrotic changes. Pathology: Current pathological examination of the medial plate of the proximal femoral epiphysis reveals abnormal structure of the normal chondrocyte area, disorganized and irregular arrangement of cartilage columnar cells, loose bone tissue, increased connective tissue located between chondrocytes and bone tissue, and delayed ossification. Clinical manifestations: There are different clinical symptoms depending on the degree of hip entropion. In the early stage, due to the abnormal development of the medial epiphyseal plate, the nuchal stem angle is not yet obvious, and both lower limbs of the child are basically equal in length, and there can be mild changes in gait; with the aggravation of the nuchal stem angle deformity, the limbs on the affected side can have obvious shortening, and for patients with bilateral onset, both lower limbs can be equal in length, and due to the relative upward and outward movement of the greater trochanter, which leads to the weakness of the gluteus medius muscle, there is a positive Trandenburg sign, and the proximal femur on the affected side can be found on the lateral side The gait lameness becomes more and more obvious, and there may be duck gait and abnormal hip function, mainly limited abduction and internal rotation. Imaging manifestations: The diagnosis can be made clearly by X-ray examination. The main manifestations are 1) reduction of the cervical stem angle, with up to 80° deformity in severe cases; 2) typical triangular bone fragments and translucent lines in the lower part of the femoral neck to V-shaped, which are characteristic changes of hip inversion; 3) upward displacement of the greater trochanter, which is significantly higher than the normal side; 4) changes in the HE angle and ATD, with the HE angle being about 25° in normal cases and significantly increased on the affected side, and the ATD, i.e., the rotor spacing, being significantly reduced Treatment and prognosis: specific The treatment plan is considered according to several factors such as age, degree of reduction of neck stem angle, limb shortening and hip function, etc. Although there are published articles on hip entropion healing on its own, there is a lack of a large amount of data support and clinical follow-up. If the cervical stem angle is less than 100° and the HE angle is more than 60°, and the age is above 4 years, surgery is recommended. There are various surgical approaches, such as Y-shaped osteotomy, Borden osteotomy, trapezoidal osteotomy, and Herdon. The main purpose of surgery is to correct the cervical stem angle to more than 120°, followed by paying attention to the angle of HE and striving to achieve normal, with special attention to the postoperative femoral neck epiphysis on the affected side, which should be made horizontal as much as possible, otherwise it will easily cause the recurrence of deformity, while paying attention to the position of the greater trochanter and performing the greater trochanter epiphyseal block appropriately, which is documented to improve the weakness of the gluteus medius muscle.The main steps of Borden osteotomy A longitudinal incision is made on the lateral side of the upper femur, the bone is osteotomized between the large and small rotors, the lateral bone cortex of the greater trochanter is excised according to the preoperative measurements, the cervical stem angle is corrected, the lateral removed bone cortex is anastomosed with the lower osteotomized end, the Blout plate determined by the preoperative cervical stem angle is implanted, the depth of the main plate is determined, the plate is fixed with screws, and the fracture is fixed in an abductor cast after surgery. After the fracture is healed, the cast is removed and functional exercise is performed.