After an injury has occurred, the following phenomena may indicate that a fracture has occurred: First, severe pain at the site of the injury, the fracture may cause severe periosteal irritation, resulting in particularly pronounced pain. Secondly, rapid localized swelling. The fracture may cause a large amount of internal bleeding and aseptic inflammation, which may lead to rapid swelling of the injury site. Third, local deformity, after such injury, if the bilateral limbs are compared, obvious deformity can be found. Fourth, localized abnormal activity, abnormal activity refers to the situation that the part that was not able to move has been able to move. Fifth, local bone friction sound or bone friction sensation, bone friction sound refers to the sound produced by the friction of the fracture end when abnormal activity occurs, and bone friction sensation is the sensation produced by the friction of the fracture end.