Regional variations in the shear strength of human lumbar vertebral endplate and trabecular bone and its relationship with density: A preliminary study

Vertebral compression fractures represent one of the most common injuries resulting from osteoporosis with an incidence rate of 700,000 per year in the United States[1]. We investigated the biomechanical shear strength of different regions of the tenth thoracic (T10) vertebra of six different human cadaveric spines. We observed a significant increase in shear strength from central to peripheral regions of the cancellous bone and endplate. There was strong positive correlation between material bone density (measured by Archimedes´ principle) and elemental shear (r² = 0.64, global shear strength (r² = 0.85), and maximum load to failure (r² = 0.86). Optical bone density (measured using ImageJ from faxitron xrays) positively correlated with shear strength although to a lesser degree.