When the two sides of the ankle joints are together, the knees should also be close together. When the distance between bilateral knees is more than 2 cm, it can be called “O-shaped leg” or “knee inversion”, which is commonly known as “loopy leg”. “O-shaped legs” is common in children aged 2 to 6 years old, which means that both lower limbs are not straight or bent, and the interval between the two knees is larger when the heels are together, making people feel that the calves are too bent, and the feet are inward when walking. Causes: 1. The cause of mild to moderate “O” shaped legs in newborns and small infants may be related to the fetal position of hip flexion and knee flexion in the womb. Most of these “O-shaped legs” are mild and can be corrected voluntarily. 2, childhood “O-shaped legs”, a considerable part of this period of suffering from “rickets” left after the sequelae, is due to calcium deficiency and caused by the softening of the bone, so also known as “chondromalacia This is also called “chondromalacia”. When these “rickets” children start to learn to walk, the softened bone will be gradually deformed under the force and form “O-shaped legs” due to the weight of both lower limbs. 3, some other diseases such as congenital tibial entropion, low phosphorus anti-D rickets, etc., can also lead to a part of children with “O-shaped legs”. Focus on prevention: the key to “O-shaped legs” in childhood is to prevent. The key to prevention is early, reasonable and adequate calcium supplementation. First of all, early calcium supplementation is especially important, and it should be done as early as during the mother’s pregnancy. The mother’s need for calcium is greatly increased when she is pregnant, so it is necessary to increase the amount of calcium supplementation during this period to prevent the baby from suffering from “congenital rickets” after birth. Secondly, the principle of reasonable and adequate calcium supplementation. Calcium supplementation should be carried out under the guidance of a child health practitioner or pediatric orthopedic surgeon, and parents should not increase or decrease the amount of calcium supplementation for their babies. Preventive and curative measures: a. If your baby has mild “O-shaped legs”, parents should not worry too much! When the baby grows up or grows to a certain age, this symptom will basically be improved. b, usually pay attention, do not let the little baby develop the habit of sitting on both lower limbs. c. Encourage your baby to do more outdoor activities or activities to increase the strength of the muscles of both lower limbs and the absorption of calcium. Most of the little patients can basically return to the normal form of both lower limbs after they go to elementary school. d. Supplement the diet with foods high in calcium such as nori, cheese, green beans, kelp, egg yolk, black sesame, shrimp, soybeans, capers, black fungus, etc. Encourage your baby to get sunlight regularly to promote calcium absorption. Tip: If you find that your baby’s “O-leg” deformity is serious, parents should be alerted to the possibility of low phosphorus anti-D rickets, and must go to a children’s hospital for consultation. For a small percentage of children whose “O-leg” deformity is too severe to return to normal, it must be corrected with the support of a pediatric orthopedic surgeon. The methods include corrective shoes, corrective braces, surgery, etc.