Flatfoot is a disease in which the arch of the foot is low or disappears, or suffers from foot exostosis, resulting in symptoms of fatigue or pain when standing or walking. Early hazards are pain on the inside of the ankle joint, aggravated after prolonged standing or walking, and the symptoms are alleviated after rest: 1. Pain: often pain on the inside of the sole of the foot, with progressive aggravation after prolonged standing or walking, sometimes pain also occurs near the lateral outer ankle; 2. Ectropion: flat feet often walk in a figure-eight position, so that the heel is easily injured and the shoes are easily worn; 3. Swelling: joint Long-term pain can lead to joint fluid leakage, developing into extra-articular swelling and affecting joint activities; 4. Abnormal gait: due to foot pain and arch collapse, it can cause a decrease in running and jumping ability or even walking ability, stumbling gait, foot shape such as outward eight, and obvious low and collapsed arch, which can lead to tarsal osteoarthritis in serious cases; 5. Other joint compensatory changes: because of the abnormal long-term gait of flat feet, such as ankle The excessive valgus and internal rotation of the ankle can cause compensatory valgus and internal rotation of the knee and hip joints, which may lead to pain and even arthritis in the lower back, hip and knee joints in the long run; 6. Ligament and tendon damage: Due to the abnormal arch structure of flatfoot patients, long-term non-correction may cause damage to ligaments and tendons, further aggravating flatfoot and making the symptoms more and more serious; 7. Decreased flexibility and even stiffness of the ankle joint can cause joint deformity.