Core tip: We often encounter people who break their feet one after another in our daily life, and even walking on a flat surface will break their feet, the frequency of broken feet is really beyond our imagination. From a medical point of view, this is actually a disease, and we clinically refer to this repeated ankle sprain problem as chronic ankle instability. We often encounter people who break their feet one after another in our daily life, and even walking on a flat surface will break their feet, which is more frequent than we can imagine. From the medical point of view, this is actually a disease, and we clinically refer to this repeated ankle sprain problem as chronic ankle instability. After an acute injury to the foot and ankle, about half of the patients will experience long-term recurrent ankle weakness and sprains, especially when the patient walks on uneven ground, the patient often feels a loss of control of the ankle joint, inversion occurs, and further sprains their foot. After the sprain may or may not be accompanied by painful swelling and some patients may feel stiffness of the ankle joint, then the patient enters the chronic instability stage. Chronic ankle instability can be classified as mechanical or functional. Mechanical instability: It means that the patient has symptoms of instability in the ankle joint, and it also shows that the ankle joint mobility exceeds the normal range of motion. Most people think that when there is more than 10mm of forward displacement on one side or more than 3mm of displacement on both sides, this is the manifestation of mechanical instability. Functional instability, on the other hand, is when the ankle mobility does not exceed the normal physiological range, but can move the ankle joint to displace for a long time after the injury, often showing symptoms such as the foot hitting soft and easy to sprain repeatedly. When the ankle joint is unstable in chronic lateral instability, that is, it may be mechanically unstable or functionally unstable. Lateral ligament rupture and laxity of the ankle joint is the main cause of mechanical instability. Functional instability, on the other hand, is related to many factors. For example, from neurological (proprioception, reflexes and muscle reaction time), muscular (strength, power and endurance) and mechanical (laxity of the lateral ligaments), all of which can affect its functional instability, such as peroneal muscle weakness. Also instability of the subtalar joint is a cause. Mechanical instability, lack of muscle growth and functional instability can occur in ankle sprains. The association between mechanical instability and functional instability has been unclear until recently. Repeated sprains due to functional instability may lead to mechanical instability. Mechanical instability and functional instability may be continuous, and the two discomforts may occur together. The persistent recurrence of pain allows both instabilities to occur at the same time. Regardless of clinical signs, most chronic collateral ligament instability syndromes present as a combination of mechanical and functional instability. Treatment: For patients with chronic ankle instability, conservative treatment can be attempted first, such as training to increase joint mobility, muscle strength training, balance improvement training, training to improve proprioception, and brace bandages and braces if necessary. 1. Muscle training (increase the key mobility of the ankle joint and the muscle strength of its nearby muscles to improve its instability) Joint mobility training of the foot and ankle: passive ankle dorsiflexion, plantar flexion, inversion, and valgus exercises Muscle strength training: resistance dorsiflexion, palmar flexion, inversion, and valgus exercises, knee flexion, and single-leg squat exercises; 2. Balance training (increase proprioception; when the ankle joint is injured, proprioception will disappear, even After the ankle pain disappears, proprioception will not recover, so we should focus on training proprioception, which is best trained on an unstable support surface) Balance mat, balance board exercises, yoga ball training; 3. Use ankle braces and patches to provide additional stability If conservative treatment is not effective, surgical treatment is needed.