X-shaped leg is a bilateral knee valgus deformity, and O-shaped leg is a bilateral knee valgus deformity. The formation of both deformities can be due to congenital factors or acquired secondary factors. Congenital factors are mainly due to congenital embryonic developmental abnormalities, and can be accompanied by abnormalities in other parts of the body. Secondary deformities are usually caused by trauma and other diseases, such as knee trauma, due to inadequate treatment and care measures, deformity healing occurs, or medial and lateral collateral ligament injuries, resulting in habitual patellar dislocation, resulting in inversion or eversion of the knee joint deformity. It is also possible that knee tumors or tuberculosis cause damage to the bone, affecting the anatomical structure of the knee, resulting in an inversion or eversion deformity. In infants and young children, rickets is caused by calcium deficiency, and X-shaped legs or O-shaped legs are formed due to weight-bearing on the lower limbs during bone development.