In case of O-leg in infants and children: First, consider congenital developmental abnormalities; second, consider symptoms caused by calcium deficiency. Pay more attention to keep warm, take the child to get more outdoor sunshine, and take oral calcium tablets and vitamin D to promote calcium absorption. If the O-leg is obvious, you can perform traction of the lower limbs with small but appropriate force to promote the recovery of O-leg. If the O-leg is more serious and the deformity is obvious, orthopedic braces for the lower limbs can be worn appropriately. With the development of the child, see if the O-leg can be gradually corrected through orthopedic brace, if it is not corrected, consider orthopedic surgery for osteotomy in adulthood.