Distribution and regional strength of trabecular bone in the porcine lumbar spine

Objective. The regional strength and distribution of trabecular bone in the porcine lumbar spine were examined to understand the mechanical responses in quadrupedal vertebrae. Design. The cancellous bone columns prepared from different regions of porcine lumbar vertebrae were subjected to axial compression to investigate the regional strength related to disc structure. Some vertebrae were also serially sectioned sagittally and transversely to observe the trabecular patterns. Background. Animal spines were often used in biomechanical testing and the results were said to be similar to those of humans. However, none of them are truly like human bipedal locomotion. The understanding of regional variations in compressive properties may help us to explain the similarity and interpret the data of animal experiments. Methods. The dried, defatted cancellous bone columns were subjected to uniaxial compression of different regions at a deformation rate of 5 mm/min. The mechanical properties in different regions were compared. The main trabecular orientation was also observed using a zoom stereo microscope. Results. The ultimate strength of the posterior column tended to be larger than that of the anterior column. The ratio of bony strength overlying the nucleus pulposus to that overlying the annulus fibrosis was constant and averaged 1.16. The main trabecular struts were noted to be parallel to the spinal canal and cross-bridged by thinner trabeculae. Conclusions. The trabecular morphology and regional mechanical properties of the porcine spine were comparable to those of other similar studies on the human spine. Its significance needed further study.