A low-density fracture line shadow is an imaging term indicating that a fracture has occurred here. A fracture is the complete or partial breakage of a bone or structure of a bone, often due to the direct action of an external force, such as a blow, a bump, an extrusion, a fall; it can also be caused by systemic diseases and diseases of the bone itself, such as osteoporosis, chondroma, osteochondrosis, and so on. It often manifests as localized pain and swelling, deformity, limited activity and other symptoms. Imaging examination shows low-density fracture line shadow, indicating that the fracture occurs here, and the fracture ends are well aligned, without obvious displacement, dislocation and separation, but only the formation of incomplete fracture or cleavage fracture without displacement. At this time, the relevant examination should be actively improved to clarify the specific degree of fracture, if the fracture is relatively stable, generally active plaster fixation and braking can be; if the fracture is unstable, surgical treatment should be given. Low-density fracture line shadow alone cannot determine the cause accurately, but also need to be combined with the characteristics of the medical history, other examination results to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of the doctor.