The initial stage of bone scab formation appears on radiographs as a tissue shadow of higher density than soft tissue and lower density than normal bone tissue around the fracture end, which can be flocculent, cloudy, striated, or clumped. It can appear between the fracture ends or around the fracture ends, gradually decreasing to the sides with the fracture ends as the center, and the overall shape is shuttle-shaped. The time of bone scab formation varies from fracture site to fracture site, and it is usually obvious in about 4-6 weeks. As time passes, the density of the bone scab increases gradually and eventually becomes similar to the density of normal bone. The shape and amount of bone scab formation varies with different fracture sites, different fracture types, different fracture alignment, and different methods of fixation. Some fractures do not form an obvious bone scab, and the healing process only shows a gradual blurring of the fracture line until it disappears, while some fractures may develop an extensive bone scab during the healing process, even in some areas where the muscles are not thick, such as the anterior calf and lower forearm, where an obvious scab can be felt on the surface.