Developmental dislocation of the hip (DDH) is one of the common limb deformities in children. It is a lesion that causes the head of the femur to dislocate from the acetabulum at birth or during development due to certain factors; it is a rather serious birth disorder that causes abnormal development, formation or dislocation of the hip joint in patients. If not treated in time, it can cause the occurrence of dislocation, joint stiffness and joint movement limitation in children, and in serious cases, it can even cause ischemic necrosis of the femoral head; at the same time, according to clinical statistics, the good or bad treatment effect of the disease is closely related to age, the younger the age, the simpler the method and the better the efficacy, so early treatment is the key to improve the quality of cure, and if it is not diagnosed and treated early, it can have serious consequences that will affect the child’s walking function. Research results show that about 10% of adult hip replacements and more than 50% of adult hip degenerative changes are associated with DDH. The morbidity characteristics can be summarized as “three highs”: first, the predominance of girls, the ratio of men to women is 1:6; second, unilateral morbidity is more common than bilateral; third, the left side is twice as much as the right side. The prevalence of the disease is 20-30% in blood relatives and 3%-4% in direct relatives of affected children. The disease is multifactorial, including the following factors: 1. congenital joint structure 2. estrogen level 3. incorrect swaddling position 4. incorrect delivery method 5. other pathological factors such as cerebral palsy, etc. Clinical manifestations Early manifestations of developmental hip dislocation: 1. one side has less lower limb movement and lower pedaling force than the other side; 2. the skin folds on the inner thighs are asymmetrical, with the skin lines on the affected side being deeper than those on the healthy side; 3. 3.When changing diapers or bathing the child, a popping sound can be heard in the hip joint area; 4.When the lower limb is in extension or flexion, the hip joint abduction is limited and the performance after toddlerhood: 1.Unilateral dislocation is mainly based on limping on the affected side. 2.Bilateral dislocation is mainly based on limping on the affected side. 2, bilateral dislocation is similar to duck gait with left and right swaying. 3. There is no pain in the initial stage, but after growing older, easy fatigue and soreness of the hip are the main causes. 4.The lower limbs are not equal in length. 5.The hip joint area is widened. 6.The hip joint is limited in abduction. Diagnosis For early detection of developmental hip dislocation, the clinic traditionally relies on medical history, physical examination and X-ray examination. Radiography only reveals the part of the hip joint that has ossified, while the hip joint of newborns and small infants is mostly made up of cartilage, which cannot be revealed by X-ray. The choice of treatment for developmental hip dislocation is as follows: 1. In neonates and infants (6 months old), non-surgical treatment, such as resetting by manipulation with plaster and/or abduction brace, is the main treatment during the period when they are not yet walking with weight. The flexion, abduction and external rotation of the hip joint is the most stable position of the hip joint, but it is important to remember that the abduction angle of the hip joint should not be too large when the cast is fixed. 2. The chance of open repositioning by surgical treatment increases significantly when the hip joint enters the period of weight-bearing walking. The combination should be applied according to the specific pathology.