Developmental hip dislocation is one of the more common congenital malformations in children, and generally the earlier it is treated, the better the outcome. If it is treated promptly and effectively in infancy, the child will have little effect on walking or life in the future. However, if the treatment is delayed, it may cause permanent limp or hip arthritis. Therefore, early detection, diagnosis and treatment are crucial for children with developmental hip dislocation. Experienced doctors can basically determine whether a child has this disease through physical examination. 1, whether the hip dermatomes are symmetrical: hip examination in hip dislocation can be seen on both sides of the dermatomes are different, and the affected side is usually elevated or increased by one. In addition, it is also often found that the proportion of thigh and calf is not proportional. While the thighs are short and thick, the calves are long and thin, the hips are wide, and the groin crease is short or indistinct. The whole lower limb is often felt to be externally turned 15 degrees to 20 degrees and shortened phenomenon. 2, the affected side can not touch the femoral head: the doctor check, usually will be suspected of the affected limb flexion of the hip and knee each 90 degrees, and then one hand holding the upper end of the calf, the other hand, the thumb placed in the inguinal ligament, the other 4 fingers placed in the buttock ring jump at the time of rotation of the hands of the calf, the normal situation in front of the femoral head can be found in the activities and protruding. In case of dislocation, the front is empty while the four fingers behind the hip feel the femoral head is moving. 3, Gary Azzi’s sign: let the baby lying down, two lower limbs flexion to 85 degrees ~ 90 degrees between the two ankles flattened in a symmetrical position, found that the two knees have high and low, known as the addition of the sign. The shortening of the femur, hip dislocation people all appear this sign. 4, adduction test: let the baby lying down, the doctor grasped both knees to do knee flexion, hip flexion 90 degrees and at the same time to the adduction, under normal circumstances, both knees can be put flat and touch the desktop. However, one side of the hip dislocation can not reach 90 degrees, often between 65 degrees to 70 degrees, the adductor muscle is obviously bulging, called positive abduction test. There is adduction to 75 degrees ~ 80 degrees between the sliding or beating feeling, but later can be more adduction to 90 degrees, called Otolani beating sound, is an important basis for diagnosis. Careful parents, by observing the baby’s lower limbs and toddler situation can be found abnormal. 1.Before learning to walk, attentive parents will find that baby’s bilateral buttock striae are asymmetrical, and the affected side’s buttock striae are usually elevated or increased by one. In addition, both lower limbs are not equal in length, and the lower limbs of the affected side are shorter than the healthy side. 2, 7 ~ 8 months began to crawl on the ground, if the baby crawls unsteadily, always to one side to, also need to consider whether there is this disease. 3, learning to walk, due to the two lower limbs are not equal in length, and thus have obvious limp when walking, such as double hip dislocation, when walking the body to both sides of a swing, a typical “duck step state”. Other relevant examinations can also be done to determine whether there is a joint dislocation. 1, the age of less than 4 months baby, the doctor may recommend hip ultrasound, such as X-ray examination, due to the epiphyseal ossification center of the femoral head has not yet appeared, the film needs to be carried out on both sides of the hip joint of the orthopedic film and both sides of the hip joint frog position combination to be able to diagnose. 2. For babies older than 6 months, the ossification center has already appeared, and the diagnosis can be confirmed by doing the orthopantomograms of both hip joints when taking the film. 3.For the older ones, further CT or MRI examination can be done, which can evaluate the bony condition of the femoral head and acetabulum, as well as the condition of the femoral head cartilage and acetabular cartilage, the round ligament, and the glenoid labrum. And measure the femoral head anterior tilt angle, femoral head and neck stem angle, etc., which is very helpful for surgical orthopedics. Due to the different ages and conditions of babies, the symptoms manifested and the examination methods adopted by the doctors will also be different. It should be emphasized that developmental hip dislocation is a gradually progressive disease, and the methods and difficulty of treatment will change and increase with age. Therefore, if parents notice any of these abnormal symptoms, they should take their babies to the hospital as soon as possible and have them examined by a doctor to confirm the diagnosis.