FLUID SIGN

The fluid sign is one of the radiological features of osteoporotic fractures, and can be helpful in distinguishing them from metastatic vertebral fractures, as it is seen more often in osteoporotic fractures and is rarely seen in metastatic fractures.

The exact pathogenesis is not known, although proposed mechanisms include spontaneous avascular necrosis of the vertebral body (or Kümmell disease) or osteonecrosis at the site of an acute insufficiency vertebral fracture.

In fractured vertebral bodies, the fluid sign was adjacent to the fractured end plates and exhibited signal intensity isointense to that of cerebrospinal fluid on a background of diffuse hyperintensity in the vertebral body because of acute collapse.

It is seen in acute vertebral compression fractures that show bone marrow edema. In osteoporotic fractures, the fluid sign was significantly associated with fracture severity.