Regional variation in the mechanical properties of cortical bone from the porcine femur.

Despite the widespread use of porcine bone as a substitute for human bone in the development of surgical technique and the use of fixation devices, relatively few studies have reported on the mechanical behaviour of porcine long bones. Regional variation in the mechanical properties of cortical bone from porcine femora was investigated using three-point bending and cutting tests. Results were related to measurements of bone architecture and composition and Rutherford backscattering spectrometry (RBS) was used to calculate the calcium to phosphorus ratio. There was significant, but limited, regional variation in the strength of the femur with bone from the distal, posterior quadrant (241.4 ± 10.43 MPa) being significantly stronger than that of the lateral quadrant (162.3 ± 17.96 MPa). Cortical bone was also anisotropic; samples cut transverse to the bone's axis were around six times tougher than those cut parallel to the axis (p<0.05). This corresponded with a significant negative correlation between the Young's modulus and toughness when cut along the longitudinal axis. RBS analysis of cortical bone samples gave a Ca:P ratio of 1.37 ± 0.035, somewhat lower than that reported for cortical bone of adult human femora. These results indicate that the mechanical properties of cortical bone show significant, but limited, variation around the porcine femur and that this should be taken into consideration when sampling and choosing an appropriate animal model for orthopaedic biomechanics research.