Fracture healing is mainly divided into: First, the hematoma inflammation mechanization period, mainly refers to the gradual hardening of the hematoma formed by the gradual cessation of bleeding and partial absorption of the fracture break within 1-3 weeks after the injury. Second, the fibrous junction period, mainly fibroblast proliferation through the hematoma. Third, the original bone scab formation period, the hematoma will gradually calcify after mechanization and gradually transform into bony tissue, the growth of bone scab can be seen on the imaging film, which takes about 8-10 weeks. Fourth, the period of bone scab remodeling and shaping, the newly formed bone scab of the fracture is messy and shapeless, osteoclasts are more active, the scab of the unstressed bone will be gradually destroyed and absorbed, the bone scab of the stressed area will be further strengthened by osteoblasts, this is a long process, it takes at least 8-12 weeks.