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 (r 2 = 0.64, global shear strength (r 2 = 0.85), and maximum load to failure (r 2 = 0.86). Optical bone density (measured using ImageJ from faxitron xrays) positively correlated with shear strength although to a lesser degree.