XO legs can be treated in the following ways: First, if the patient’s epiphysis is not closed, is an infant or young child and the valgus angle is <15 degrees, heel pads can be worn. If the angle of valgus is >20 degrees and the parents also suffer from knee valgus, the patient should be immobilized by wearing a corrective brace at night. In adolescents, surgery is required to correct the deformity. In young children, most knee valgus can be corrected on its own. Secondly, if the patient is an adult and the epiphysis has closed, surgical treatment is needed. Periprosthetic osteotomy includes proximal tibia and supracondylar femur osteotomy to correct the deformity of the leg, of which proximal tibia osteotomy is mainly used to treat patients with inversion of the knee, while supracondylar femur osteotomy is mainly used to correct the deformity of knee valgus.