Fracture line blurring is usually the second and third stage of the fracture healing process, which is a complex process that is continuous. From the histologic and biological changes, it can be divided into three phases, which are not separable from each other and are intertwined in their evolution. After the fracture occurs, it first enters the phase of hematoma mechanization evolution, in which the fracture breaks are connected by fibrous connective tissue, which usually takes about two weeks to complete. The primitive scab formation phase, which usually starts in about two weeks, takes 4-8 weeks to maintain, and at this stage the fracture line can appear blurred, but the fracture breaks are generally stable and not strong. In the third stage, that is, the bone scab remodeling and shaping period, the fracture line is more obvious, and may even be in the process of the fracture line completely disappeared. At this time, the stability of the fracture end is significantly improved, and the recovery of the fracture enters the final stage.