Lateral ligament injuries account for 90% of ankle sprains, and 20-30% of patients develop chronic lateral ankle instability. Lateral ankle instability refers to damage to the lateral stabilizing structures of the ankle joint, resulting in ankle osteoarthritis and dysfunction caused by frequent inversion of the ankle joint. Mechanical instability and functional instability are not mutually exclusive, but there is a degree of crossover. It is one of the most serious complications of ankle sprains. Ankle instability can be divided into mechanical instability (presence of laxity of the lateral ligaments or joint capsule beyond the normal range of motion) and functional instability (no anatomical laxity, but rather impaired proprioceptive function and insufficient control of force and posture, not beyond the normal range of motion). The main clinical manifestations are: chronic pain after ankle sprain or distrust of the ankle joint in patients with repeated sprains, as well as the patient’s fear of walking on uneven ground or inability to walk on uneven ground and discomfort during starting and stopping. Examination: pressure pain on the lateral aspect of the ankle joint, positive drawer test and talus tilt test. Imaging: X-ray film examination is an important tool. A talar tilt >9° in the stress position and a positive hallux valgus >10 mm on the anterior talar drawer test indicate the presence of instability. MRI of the ankle joint can then reveal the injured ankle ligaments more clearly. Treatment: Conservative treatment is the preferred treatment option for chronic lateral ankle instability. Treatment includes ankle bandages, braces, orthotics (e.g., wedge elevation of the lateral heel), peroneal muscle strength training, proprioceptive training, hydrotherapy, and stationary cycling exercises to improve joint mobility, with the ultimate goal of restoring joint function to the patient’s intended state, including dancing, sports, and labor. However, this must be done under the guidance of a regular foot and ankle surgeon, otherwise new injuries may result from improper methods. Patients whose symptoms are not relieved by regular conservative treatment need surgical treatment. There are more than 50 surgical procedures for the treatment of chronic lateral ankle instability. There are two general categories: (1) in situ anatomic suturing of the ligamentous stops (e.g., Brostrom procedure); and (2) non-in situ tendon fixation using part or all of the peroneus brevis or other autologous or artificial tendons (e.g., Chrisman-snook, Watson-Jones, Evans procedure).