Antero-postero differences in cortical thickness and cortical porosity of T12 to L5 vertebral bodies.

OBJECTIVE: This study will investigate interrelationships between the cortical shell and cancellous bone trabecular thickness, in vertebral bodies.
METHODS: One hundred and sixty vertebral bodies from T12 to L5 were obtained at autopsy. The average age of the cohort was 59.3+/-22.1 years (range = 20-94 years). Cortical thickness, cortical porosity and trabecular thickness from the adjacent cancellous bone were measured.
RESULTS: At the mid-vertebral body anterior cortical thickness was significantly greater than posterior cortical thickness (524 +/- 352 vs. 370 +/- 283 microm, respectively, P < 0.0001) and mid-anterior cortical porosity was significantly less than mid-posterior cortical porosity (24 +/- 14% vs. 32 +/- 16%, respectively, P < 0.0001). There were no anterior/posterior differences in trabecular thickness of the cancellous bone adjacent to the cortical walls.
CONCLUSION: This study provides a novel perspective of T12 to L5 vertebral body bone, where measurement of cortical thickness and cortical porosity in a cohort of skeletally normal individuals revealed structural differences between load bearing anterior and posterior cortical walls. The data suggest that modulators of change to vertebral body bone may affect the cortical and trabecular bone differently. The relationships between cortical and cancellous bone suggest that the middle sectors of the vertebral body play a critical role in load bearing.