Many patients with ankle sprains have this experience: after a single sprain of the ankle, the ankle is often sprained again, and it always feels unstable and easily fatigued. What is the reason for this? As you know, after spraining the ankle joint, the ligaments around the joint are damaged and may also cause fractures. After a period of braking and recuperation, the pain in the ankle disappears or decreases, the swelling subsides, and the patient starts to move around, after which the above symptoms appear. This phenomenon is called chronic ankle instability. The factors that cause ankle instability after ankle injury are: 1. Muscle atrophy and muscle strength decrease around the calf, especially muscle atrophy of the outer calf (fibular long and short muscles atrophy). 2. Patients will experience decreased proprioception after ankle injury. The so-called proprioception is: the sensation produced by the muscles, tendons, joints and other motor organs themselves in different states (movement or rest) (for example, a person can perceive the position of various parts of the body when the eyes are closed). It is also called deep sensation because of its deep location. The absence of proprioception can cause re-injury. 3. Injury to the ligaments around the ankle joint with reduced ligament tension. Rehabilitation medicine is the treatment of choice for ankle instability. Patients improve muscle strength and increase muscle capacity through muscle strength training. The proprioception of the joint is improved through balance function training and motor ability control training. Strengthen the repair and strength of the joint ligaments through physical factor therapy. Increase the stability of the ankle joint to prevent joint re-injury through the above treatments.