Environmental Health Perspectives

Background: Metastatic diseases and infections frequently involve the spine. This is the result of seeding of the vertebral body by tumor cells or bacteria delivered by venous blood from Batson's plexus, which is hypothesized to enter the vertebral body via the epidural veins. Isolated spinal segments deform significantly at the bony end plate when under compression. This deformation could cause a volume change of the vertebral body and may be accompanied by retrograde flow of venous blood. To date, this process has not been investigated quantitatively. The purpose of this study was to determine the volume changes of the vertebral body and basivertebral vein for a vertebral body under compression. Methods: A three-dimensional finite element mesh model of the L4 segment with both adjacent discs was modified from a 3-D computed tomography scan image. An octagon representing the basivertebral vein was introduced into the center of the vertebral body in the model. Four compressive orientations (1500 N) were applied on the top disc. The volume change of the vertebral body model and the basivertebral vein were then computed. Results: The volume change of the vertebral body was about 0.1 cm3 (16.3% of the basivertebral vein) for the four loading conditions. The maximum cross-sectional area reductions of the basivertebral vein and volume reduction were 1.54% and 1.02%, for uniform compression. Conclusion: Our study quantified the small but significant volume change of a modeled vertebral body and cross-sectional areas and that of the basivertebral vein, due to the inward bulging of the end plate under compression. This volume change could initiate the reverse flow of blood from the epidural venous system and cause seeding of tumors or bacterial cells. Background It is well-known that the venous drainage network for the bony vertebral column is unique [1-4]. The caliber of the basivertebral veins of the vertebral body is far out of proportion to similar venous drainage systems for other bones of the body, including large weight-bearing bones [1,5]. Venous blood drains from the basivertebral vein into the epidural system via the central vascular foramen Published: 27 December 2006 Journal of Orthopaedic Surgery and Research 2006, 1:18 doi:10.1186/1749-799X-1-18 Received: 11 April 2006 Accepted: 27 December 2006 This article is available from: http://www.josr-online.com/content/1/1/18 © 2006 Yeh et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.