The main cause of radial tuberosity subluxation in the pediatric population is that there are many bones, muscles, and ligaments that are underdeveloped in childhood, and one that is more closely related to pediatric radial tuberosity subluxation is the annular ligament. What does the annular ligament do? The radial tuberosity is round, and the annular ligament wraps around the radial tuberosity in a circle, which is equivalent to a ring to hold it in place. In childhood, the annular ligament is not particularly well developed, as the saying goes, it is not strong enough, so it is easy to detach from the radial tuberosity, after detachment, it is stuck in the brachioradial joint, which is the same as the ligament had not been in the joint, and then ran to the joint inside, will inevitably take up the space occupied by the original radial tuberosity, and squeeze the radial tuberosity out of the joint. Medically, it is called radial side movement, which is commonly known as movement toward the lateral side of the elbow joint, and it moves partially, causing the radial tuberosity to be in a different position than it was originally, but it is not completely dislodged. That’s why it’s called a radial tuberosity subluxation. Some people call it annular ligament subluxation, talking about the same disease.