If the fracture is to be seen on film to show scab growth, the fracture line at the fracture end must be observed to be clear and must be compared to a photograph of the immediate injury. If the fracture line appears very clearly blurred, it means that there has been primitive scab growth. If the scab is gradually growing more vigorously, a periosteal reaction will be seen in the bone cortex around the fracture end, that is, a curved layer of high density shadow will be seen in the outer layer of the bone cortex at both ends of the fracture, this condition is a periosteal reaction and there is a preliminary outer layer of scab formation. As the scab gradually grows, the inner layer of the curved high-density shadow will gradually increase in density, which means that the scab is growing more vigorously.