Introduction - The pathophysiology of intravertebral vacuum (IVV) remains unclear, although vertebral osteonecrosis is often incriminated. Gas may migrate from the disk to the vertebral body. The objective of this study was to investigate the relations between IVV and intradiscal vacuum (IDV).

Methods - We prospectively evaluated the presence of radiological findings suggestive of IVV in patients admitted to a rheumatology department for vertebral fracture, over a 6-year period. Suggestive radiological findings were defined as a radiolucent collection within a vertebral body, an increase in the anteroposterior diameter of the vertebral body, and/or evidence of horizontal dissection of a vertebral body. Patients with any of these findings underwent computed tomography; when this investigation showed IVV, the adjacent disks were examined for IDV, and when this was found a communication between the two cavities was looked for.

Results - Of 278 patients admitted for vertebral fracture during the study period, 15 had IVV. IDV adjacent to the fractured endplate was visible in 13 of these 15 patients. All 15 patients had severe fractures (Genant semi-quantitative classification, grade 3 in 10 patients and grade 2 in five patients). A communication between the intradiscal and intravertebral collections was seen in five patients. Only two patients had evidence of IVV on plain radiographs.

Conclusion - Our findings support migration of gas from the disk to a fracture in the adjacent vertebral body. The term “vertebral osteonecrosis” used to designate IVV may be inappropriate. IVV is rarely shown by plain radiographs, indicating a need for other morphological criteria.