DISTRIBUTION AND REGIONAL STRENGTH OF TRABECULAR BONE IN THE PORCINE LUMBAR SPINE

Objective. The regional strength and distribution of trabecular bone i n the porcine lumbar spine were examined to understand the mechanical responses in quadrupedal vertebrae. Design. The cancellous bone column s prepared from different regions of porcine lumbar vertebrae were sub jected to axial compression to investigate the regional strength relat ed to disc structure. Some vertebrae were also serially sectioned sagi ttally and transversely to observe the trabecular patterns. Background . Animal spines were often used in biomechanical testing and the resul ts were said to be similar to those of humans. However, none of them a re truly like human bipedal locomotion. The understanding of regional variations in compressive properties may help us to explain the simila rity and interpret the data of animal experiments. Methods. The dried, defatted cancellous bone columns were subjected to uniaxial compressi on of different regions at a deformation rate of 5 mm/min. The mechani cal 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 th an that of the anterior column. The ratio of bony strength overlying t he nucleus pulposus to that overlying the annulus fibrosis was constan t and averaged 1.16. The main trabecular struts were noted to be paral lel to the spinal canal and cross-bridged by thinner trabeculae. Concl usions. The trabecular morphology and regional mechanical properties o f the porcine spine were comparable to those of other similar studies on the human spine. Its significance needed further study. Relevance T he similarity of trabecular orientation and disc-related regional stre ngth in the porcine and human lumbar spine implies that the main resul tant force acting on the end-plate is also similar. Some anatomical ad aptation may be responsible for this finding. (C) 1997 Elsevier Scienc e Ltd. All rights reserved.