First, “X”-shaped leg, also known as knee valgus, refers to the knee joint below the turn to the outside, the gap between the knees becomes smaller due to the cause of the disease is still unclear. Clinical manifestations: Mostly seen in children, mostly bilateral, both lower limbs are “X” shaped leg. When bearing weight, the ground reaction force and their own weight superposition, so that the bilateral knee and calf external rotation more obvious. When running, both knees are easy to collide and fall. If the legs remain in an incorrect position for a long time, the medial collateral ligament and the anterior cruciate ligament can be stretched to laxity, causing instability, fatigue and even pain in the knee joint. The stress surface of knee and ankle joints is not horizontal, which may cause joint deformity for a long time. Generally, “X”-shaped legs are accompanied by flat feet, but children with flat feet may not necessarily have “X”-shaped legs. It should be considered in conjunction with the specific clinical manifestations of the child. Second, “O” shaped leg, also known as bowed leg or knee inversion. The knee joint turns inward and the gap between the knees is too large. Clinical manifestations: Mostly seen in children, mostly bilateral, both lower limbs are “O” shaped leg. When bearing weight, the ground reaction force and their own weight superimposed, so that the bilateral knee and calf internal rotation is more obvious. When running, the lower limbs show an arc gait. If the legs remain in an incorrect posture for a long time, the lateral collateral ligaments and posterior cruciate ligaments may be stretched to laxity, causing instability, fatigue and even pain in the knee joint. The stress surface of knee and ankle joints is not horizontal, which may cause joint deformity for a long time. Outpatient clinics have seen many cases of adolescents, according to the family statement and clinical diagnosis of the following situations, need to cause the child’s family attaches great importance to: 1, some children in the prenatal fetal position caused by some deformities of the lower limbs, such as “X”, “O” shaped legs. These children are rare. 2, the child did not use a wide elastic bandage to tie the legs within three months when he was an infant, because the volume of the diaper is too large or the choice of unsuitable diapers caused the child’s double lower limb force line is not in a straight line. This type of children is common, basically accounted for 60% of the “X”, “O” shaped legs. 3, the child in 8 months – 1 year old, in the walker to practice standing and walking, and many family members due to negligence did not carefully observe the posture of the child in the walker, if once there is a trend of “X”, “O” shaped legs, with the increase in age and body weight, it will become more and more serious. 4. Nowadays, the standard of living is improving day by day, and children in childhood are more and more picky about food, which causes the lack of many trace elements in the body, including bone calcium and blood calcium. Some family members have reflected to me: “Our child has been supplementing calcium”, but please ask, has the child absorbed it. This is a problem that needs to be brought to the attention of the majority of families. 5, most of the children with “X”, “O” shaped legs are obese or the body grows faster in a certain period of time, which will aggravate the changes of “X”, “O” shaped legs. To summarize, now most families are only children, the care of the child should not only be reflected in the life and learning, in the child’s growth and development stage, read some necessary medical knowledge is very necessary, it is recommended that the majority of parents and friends of their children to do some regular health checks. This can avoid many problems, early detection, early treatment.