O-shaped legs in children may be related to traumatic factors, or may be caused by chondrodysplasia, rickets and other reasons. 1. Traumatic factors: if the child in ordinary times due to accidental trauma, resulting in bone fracture, if not well treated, resulting in malformation of the fracture healing, may cause the child O-shaped legs. 2. Chondrodysplasia: this disease belongs to the skeletal dysplasia disease, mostly considered to be due to genetic anomalies and hereditary diseases, which can lead to the child’s limbs are short, or disproportionate, which may cause O-shaped legs, may also be accompanied by intermittent claudication, hypotonia and other symptoms. 3. Rickets: this disease is usually caused by the serious lack of calcium and vitamin D in children’s bodies, which can lead to softening or deformity of bone tissue, which may cause O-shaped legs, and may also be accompanied by excessive sweating, irritability and crying, funnel chest and other symptoms. Children with O-shaped legs may also be caused by other reasons. When children are found to have O-shaped legs, they should seek medical treatment as soon as possible to clearly diagnose the causes and then give targeted treatment.