XO leg refers to X-shaped leg and O-shaped leg, which are also known as knee valgus and knee valgus respectively. Knee valgus means that when both lower limbs are naturally straightened or standing, the inner sides of both knees are in contact with each other, but the ankles can not be brought together and are separated from each other; Knee valgus means that when both lower limbs are naturally straightened or standing, the inner ankles of both feet can be brought together, but the knees can not be brought together. Physiological knee inversion refers to the natural phenomenon during the growth and development of children, with the child’s standing and walking, knee inversion will gradually disappear; pathologic rickets is the main cause, osteoarthritis, osteochondrosis can also lead to knee inversion and outversion. If you have the above symptoms or are diagnosed with X-shaped legs and O-shaped legs, it is recommended that you go to the hospital in time for standardized treatment under the guidance of the doctor.