Developmental dysplasia of the hip (DDH), formerly known as congenital hip dislocation, is a general term for a group of pathologies characterized by spatial and temporal instability of the hip joint during development, including hip dislocation, subluxation and acetabular dysplasia. DDH can cause abnormal gait, abnormal development of adjacent joints, and secondary deformities of the spine in children, leading to lower back pain and pain in adulthood at Zhengzhou University First Affiliated Hospital for Pediatrics. Chen Xinjian Pain caused by degenerative hip joint degeneration. Because the disease is closely related to the developmental process of the hip joint, the manifestations and corresponding treatments vary among different age groups. The goal of DDH treatment is to obtain a stable concentric reposition and avoid ischemic necrosis of the femoral head. Early diagnosis and treatment is the key to improve the outcome. （This stage is the prime time for DDH treatment, with easy and simple methods, good compliance, reliable efficacy and few complications. 1. Clinical manifestations and signs: asymmetry of thigh skin pattern and hip pattern, joint popping and unequal length of lower limbs. Limited hip abduction on the side of dislocation. The limbs are not equal in length, etc. 2. Imaging examination: ultrasound of hip joint is preferred for children ≤4 months old; X-ray double hip orthopantomographs can be taken for children >4 months old. 3. Treatment: Pavlik sling is preferred, other treatment methods include brace (fixed in the same position as the sling) or direct closed and repositioned plaster fixation, but care should be taken to avoid damaging the femoral head cartilage and causing femoral head necrosis. (B) 7 months～18 months With the increase of age, weight and activity, the compliance and efficacy of the sling decreases. 1. Clinical manifestations and signs: asymmetrical appearance of both hips, wide perineum, unequal limbs, late partial walking and claudication. 2. Treatment: closed repositioning under anesthesia and plaster tube type fixation in human position is preferred. After this treatment, the child has different conditions: (1) concentric head and socket reset; (2) head and socket reset but residual acetabular dysplasia; (3) residual subluxation; (4) residual femoral head necrosis; different treatment measures are used in different cases. （Clinical manifestations and signs: limp, duck walk, unequal lower limbs, increased lumbar lordosis, limited hip abduction, positive Allis sign, positive Trendelenburg sign, etc. 2. Imaging examination: X-ray orthopantomogram of both hips, with the same assessment indexes as before. CT three-dimensional reconstruction is an effective means to observe the anterior femoral tilt angle and posterior dislocation. 3. Treatment: It is still possible to try closed repositioning within 2 years of age, but most children need incisional repositioning and osteotomy. Clinical manifestations and signs: In addition to the above-mentioned manifestations, attention should be paid to the presence of fatigue pain and (in children with subluxation) end-of-motion extrusion pain of the joint. 2. Imaging examination: X-ray orthopantomographs of both hips should be evaluated as before, and attention should be paid to the presence or absence of osteoarthritis in the semi-dislocated joint. CT three-dimensional reconstruction can also assess the morphological adaptation of the head socket, in addition to observing the anterior tilt angle and posterior dislocation. Treatment: The aim of treatment for unilateral dislocation is to maximize the restoration of anatomy and function and to create conditions for joint replacement. Equalize the length of the lower extremity to prevent secondary spinal deformity. The prognosis of surgical complications in bilateral dislocation without pseudosocket formation is worse than the natural prognosis, and treatment can be abandoned. Bilateral dislocation with pseudoacetabular formation is prone to early onset arthritis and can be treated as palliative care. Early treatment has a great impact on the prognosis of developmental dysplasia of the hip (DDH), and many foreign countries have already started screening for developmental dysplasia of the hip in the neonatal period, but in China, due to various reasons, relatively few cities in China are currently carrying out screening. Even for asymptomatic children, if conditions allow, they can go to the pediatric orthopedic department of a regular hospital for neonatal screening, the simplest of which is a physical examination and a noninvasive ultrasound examination, so that problems can be detected early and treated promptly to avoid serious consequences. Department of Pediatric Orthopedics, The First Affiliated Hospital of Zhengzhou University Clinic hours: Tuesday, Thursday, Saturday morning Tel: 0371-67967252 Address: The First Affiliated Hospital of Zhengzhou University, No. 43, University Road, Erqi District, Zhengzhou City Outpatient Clinic: Pediatric Surgery Clinic, 6th Floor, Outpatient Building Ward: Pediatric Surgery Ward 1, 25th Floor, Ward Building No. 2