1. 1 Growth characteristics On the basis of relatively active growth, children's bones have about two rapid growth periods, one is from birth to 3 years old; The other is adolescence (average girl 1 1~ 13 years old, boy 12~ 14 years old). In addition, children's individual differences are also great.

1.2 characteristics of injury repair ① children's bones contain more organic matter, and the younger they are, the greater the proportion of organic matter. Therefore, children's bones are elastic and tough, easy to deform, and may break constantly in the face of violence, resulting in cracks or green branch fractures. ② The children's periosteum is thicker than that of adults, and it is not easy to rupture during trauma, and usually remains connected on one side of the fracture. Therefore, children generally have less displacement after fracture, which is helpful for stable reduction. (3) The growth mechanism of children's bones (including bone energy, energy plate, periosteum and other structures) is often damaged, which is a unique bone injury in childhood and the most important part of children's bone injury. ④ The growth and shaping of bones are closely related to children's age, and children have a strong ability to compensate and correct the unsatisfactory reduction after fracture. ⑤ The ability of bone growth and repair is closely related to age. The younger the age, the less mature the bone development, the more active its metabolic growth function, and the greater the repair potential once it is damaged.