Load Sharing within a Human Thoracic Vertebral Body:

The spine play very crucial role in bearing body weight. The loads acting upon a vertebra are borne by vertebral bodies and facet articulations. The vertebra has a composite structure, composed of large trabecular bone surrounded by thin cortical bone. The cortical and trabecular components share the load when the vertebra undergoes axial loading. The distribution and transmission pathway of the load within a vertebral body is still not well understood despite of some studies in the literature (Rockoff 1969, Cao 2001). The strength of these two components of bone and distribution of the loads between them determines the capability of the spine to resist compressive fractures. In addition, the vertebra is affected severely by osteoporosis changing the load distribution across the vertebra and increasing likelihood of vertebral fracture. Therefore, it is very important to understand the contribution of cortical and trabecular bone to load bearing applying on a vertebra. The present study was thus designed to quantify the percentages of the load transmitted by the cortical and trabecular bone.