Rattling in the ankle joint is usually due to degeneration of the cartilage in the ankle joint caused by excessive friction, resulting in deformation, edema, or even fracture of the cartilage surface. When the ankle joint is flexed or extended, or when the ankle joint is subjected to stress, the damaged cartilage rubs abnormally, causing a distinctive rattling sound in the ankle joint. Then there is the obvious stiffness and reduced relaxation of the ligament capsule around the ankle joint, which is related to strain and cold, resulting in tightening of the joint area and causing abnormal friction of the cartilage surface of the joint, resulting in a rattling sound when the ankle joint is moved.