THE INTRAVERTEBRAL VACUUM PHENOMENON (VERTEBRAL OSTEONECROSIS) - MIGRATION OF INTRADISCAL GAS IN A FRACTURED VERTEBRAL BODY

Study Design. Retrospective cohort. Objectives. To compare the prevale nce of the association between contiguous intervertebral disc and vert ebral collapses with or without an intravertebral vacuum phenomenon. S ummary of Background Data. The mechanism of occasional gas accumulatio n within some vertebral collapses is poorly known. The current hypothe sis is that this phenomenon is indicative of bone ischemia. In fact, a vascular necrosis as the main pathologic event remains speculative, an d should not explain per se the presence of gas within a vertebral bod y. Methods. Comparison of the prevalence of intervertebral disc vacuum phenomenon adjacent to the affected vertebral body in 23 cases of int ravertebral vacuum phenomenon in 19 patients (intravertebral Vacuum ph enomenon group) and in 708 osteoporotic collapses without intravertebr al vacuum phenomenon in 199 patients (control group). Results. There w ere no differences in sex and age between the two groups, and all the patients in the intravertebral vacuum phenomenon group had signs of un derlying osteoporosis. A Vacuum phenomenon in at least one interverteb ral disc adjacent to the collapses an radiographs, conventional tomogr aphy, computed tomography, or magnetic resonance imaging was found in 19 cases (83%) in the intravertebral vacuum phenomenon group, compared with 13% in the control group (P < 0.0001). Considering plain radiogr aphs only, this association was found in 50% of the intravertebral vac uum phenomenon group and in 9.7% of the control group (P < 0.0001). Th e intervertebral and intravertebral gaseous collections were connected through a fractured endplate in six cases. Conclusions. The high prev alence of the association of contiguous intervertebral and intraverteb ral vacuum phenomenon could have implications in the pathogenesis of t he intravertebral vacuum phenomenon. We hypothesize that the intravert ebral vacuum phenomenon could:simply be the result of migration of an intradiscalgaseous collection through the fractured endplate of ;some osteoporotic collapses.