MRI fluid sign is reliable in correlation with osteonecrosis after vertebral fractures: A histopathologic study

Introduction: Magnetic resonance images (MRI) fluid sign and intravertebral vacuum phenomenon of the plain radiograph are considered as the characteristic radiological findings for vertebral osteonecrosis after spinal fractures. We aim to study the association between the radiological and histopathologic findings of vertebral osteonecrosis through the use of an open retrieval of specimens. Materials and methods: Twenty consecutive patients (54-84 years, mean 73 years) of unstable vertebral compression fractures treated with anterior corpectomy and fusion were included. All the images and pathologies were correlated, especially the histopathologic changes to the fluid sign and vacuum phenomenon. Results: MRI fluid signs and the histopathologic findings of vertebral osteonecrosis were significantly correlated and both were noted in the first 5 months after injury. The power of the fluid sign in diagnosing vertebral osteonecrosis was better than that of the intravertebral vacuum phenomenon (diagnostic odds ratio 65 vs. 2, sensitivity 86 vs. 50 %, specificity 100 vs. 67 %). Conclusion: MRI fluid sign is more predictable to diagnose vertebral osteonecrosis in operative case, especially within the initial 5 months after injury.