Fracture healing is roughly divided into three phases, namely, the hematoma inflammatory mechanization phase, the primary bone scab formation phase, and the bone scab remodeling and shaping phase. 1. Hematoma inflammation period: usually from 6 hours to two weeks after injury. It refers to the hematoma formed at and around the broken end of bone fracture, the blood clot formed by activated coagulation system, and the aseptic inflammation caused by necrosis of part of soft tissues and bone tissues, which is gradually cleared under the action of neutrophils, etc., so as to make the hematoma mechanize and form granulation tissues. 2. Primary bone scab formation period: it usually takes 2 to 6 months. It refers to the formation of intramembranous bone by periosteal hyperplasia, neovascularization, osteoblast proliferation, etc., and then there are endosteal and periosteal membranes close to the bone cortex to form endosteal and exosteal bone scabs, which are continuously calcified to achieve clinical healing. 3. Scab transformation and shaping period: usually takes 1~2 years. It refers to the process of necrotic bone at the fracture end through the invasion of osteoclasts and osteoblasts to complete the removal of dead bone and the formation of new bone to crawl and replace. If there is a fracture, it is recommended to go to the regular hospital in time to avoid delaying the condition.