O-shaped leg means that the patient’s lower limbs are not able to straighten or stand normally, and the two knees are not able to come together, resulting in an O-shaped leg. It is also known as O-shaped leg, which is medically known as “inversion of the knee”. It is a deformity in which the inner ankles of the feet touch each other but the knees do not come together when the lower limbs are naturally straightened or standing. The treatment of O-shaped leg can be corrected by physical therapy or surgery. 1. Physical therapy: patients can improve O-shaped legs through instrumental correction and corrective insoles. Instrumental correction is mainly to adjust the ligaments of the inner and outer knee joints to help the recovery of O-shaped leg. Corrective insoles can increase the power of outward rotation of the calf to avoid aggravation of O-shaped leg. 2. Surgery: If the degree of O-shaped leg is very serious, the patient can use surgery to correct it, otherwise it may affect the patient’s daily life and walking. For the early prevention of O-shaped leg, it is necessary to supplement nutrition to avoid calcium deficiency and other lesions.