The human elbow joint consists of three bones: the lower humerus, the ulnar hawk and the radial tuberosity. When the elbow joint is rotated, the radius always rotates around the ulna. To prevent the radius from dislocating during rotation, the ulna has a ring-like ligament that tightly holds the “neck” of the radius – the radial neck. In children under four years old, the ligaments and joint capsule of the elbow joint are not yet well developed, and the radial tuberosity and the radial neck are basically the same diameter. It is like a knot tied to a round log, if the wood is as thick and thin, the knot will easily slip off. Therefore, when the elbow joint is straightened and the forearm is internally rotated, the radial tuberosity will detach downward from the annular ligament if it is stretched longitudinally. When an adult is leading a child, the child’s elbow joint is in a straightened, internally rotated forearm position, so it is easy for the radial tuberosity to subluxate. Because it is caused by pulling, it is also called “pulling elbow” in clinical practice. After radial head subluxation, the affected limb drops down and is afraid to move. There is significant pressure pain at the radial tuberosity, but the radiograph is normal. Due to sensory differences, some children will always say that their hands hurt, and with thicker clothing in winter, they often cannot detect the elbow joint problem. Although some children cannot say where the pain is, the child will refuse to use and move the affected limb. Parents will usually think it is a shoulder or wrist problem. If the child has had a pull on the forearm prior to this, the diagnosis is basically confirmed. Manipulation is more effective after radial tuberosity subluxation, but it is best to have an orthopedic surgeon do it because it requires some skill and to prevent missing other conditions. After resetting, the child will immediately stop crying and the injured limb can be moved. No immobilization is usually required, but parents must avoid pulling the limb too hard or too vigorously. When dressing the child, parents should be gentle and go along with the child, do not pull and drag; when holding the child’s hand to walk or up and down steps, do not lift the child’s arm like lifting something; usually do not pull the child’s arm to lift him up to play. After the child is 6 years old, the radial head and annular ligament development is basically formed, rarely re-occurrence, parents do not need to distress.