The main manifestations of arm dislocation in infants are joint deformity, pain, swelling and bruising, and elastic fixation of the joint. 1. Joint deformity: the elbow joint of the arm loses the normal joint structure relationship, resulting in abnormal joint shape. When it is a small radial subluxation, the joint deformity is not obvious. 2. Pain: Because the dislocation is the result of violent trauma and spasm around the joint, there will be obvious pain, and the baby will show crying and other behaviors. 3. Swelling and bruising: when the bone leaves its original position, it will compress the surrounding blood vessels and nerves and so on, thus leading to swelling and bruising. 4. Elastic fixation of joints: The loss of normal joint structure affects the range of motion of the joints. There is a feeling of the joint being stuck in the process of movement. Dislocation of the baby’s arm can lead to compression of blood vessels and nerves leading to injury, should go to the hospital as soon as possible to reset, so as not to delay the condition.