Congenital dislocation of the hip (CDH) is a congenital disorder of the hip joint of unknown origin in childhood, the incidence of which is about 1‰ in Europe and the United States and 0.5‰ to 2‰ in China. In adults, congenital dislocation of the hip or acetabular dysplasia is usually caused by missed diagnosis, delayed treatment or inappropriate treatment during childhood, or by natural regression of other childhood hip diseases such as Legg-Carlve-Perthes disease and slipped epiphysis of the femoral head. In adulthood, the pathological changes and clinical manifestations are already quite serious. As the material, technology, prosthesis design and surgical technique of total hip arthroplasty (THA) have become more and more perfect and mature, THA has become one of the important treatment options. Crowe’s classification: Crowe et al. classified the dislocation of the femoral head into 4 types according to the ratio of the displacement distance of the femoral head to the height of the femoral head and pelvis measured by X-ray. Type I: femoral head displacement accounted for less than 50% of the femoral head height or less than 10% of the pelvic height; Type II: femoral head displacement accounted for 50%-75% of the femoral head height or 10%-15% of the pelvic height; Type III: femoral head displacement accounted for 75%-100% of the femoral head height or 15%-20% of the pelvic height; Type IV: femoral head displacement exceeded 100% of the femoral head height or 20% of the pelvic height. The head of the femur is displaced more than 100% of the height of the femoral head or 20% of the height of the pelvis. ②Hartofilakidis classification: Hartofilakidis et al. classified CDH into 3 types according to the degree of dislocation of the femoral head: Type I: acetabular dysplasia: i.e., the femoral head is semi-dislocated, and most of the femoral head is still contained in the true socket, but there is mostly shallow acetabulum and bony defects on the upper edge of the acetabulum; Type II: low hip dislocation: the femoral head is on the iliac wing with a pseudosocket forming Type III: high dislocation: the head of the femur is clearly displaced upward and backward, and the head of the femur is articulated on the iliac wing with a distinct, independent prosthetic socket, and there are bone defects on all four walls of the acetabulum. (iii) Eftekhar’s classification: Eftekhar proposed a 4-stage classification based on the progression of the disease: stage 1: the acetabulum is only mildly elongated and dysplastic, and there is a developmental deformity of the femoral head; stage 2: there is a pseudosocket that partially overlaps with the true socket; stage 3: there is a high, independent pseudosocket; stage 4: the femoral head is dislocated upward and backward, but not in contact with the iliac wing. stage 4: the head of the femur is dislocated upward and backward, but not in contact with the iliac wing. Kerboul’s classification: Kerboul et al. proposed that CDH could be divided into two categories based on various considerations such as the local bone volume of the acetabulum, the tilt of the acetabulum, the contracture of the surrounding soft tissues, the deformity of the knee joint, and the unequal length of the limb, in order to facilitate the preoperative planning of hip arthroplasty: namely, high hip dislocation and subluxation. Among all the classification methods of CDH, Crowe’s method has been adopted by most scholars because of its simplicity and practicality, its high quantitative component, and its ability to compare the results of different authors and different procedures. Hartofilakidis’ method is also often used because of its simplicity and practicality. Indications for THA: The selection of indications for THA in the treatment of CDH should be based on a number of factors such as the severity of the disease, the degree of secondary degenerative osteoarthritis of the hip, the age of the patient, the patient’s expectation of functional recovery of the hip joint, and the local bone volume available around the hip joint. In most cases, adults with CDH with severe hip pain and claudication and patients with high functional requirements of the hip can be candidates for total hip surgery.