Infant arm dislocation is characterized by abnormal crying, and the affected limb cannot move freely. Because the development of infants’ joints is still incomplete, the ligaments, muscles and joint capsule of the joints are relatively loose, when accidentally pulling the infant’s arm, it is easy to cause the radial tuberosity semi-dislocation, i.e., dislocation of the arm. 1. Abnormal crying: infants can not express pain through language, so after dislocation of the arm for sudden crying, different from the previous persistent crying, parents are difficult to coax good. 2. The affected limb can not move freely: the performance of the hand is not as free as in the past to grasp, elbow joints straight dare not flexion, rotation, accidentally touch the affected limb, the baby crying will be significantly increased. After the dislocation of the baby’s arm, you need to go to the regular hospital in a timely manner, the doctor can restore most of them to normal after manipulation and reset.