Biaxial Mechanical Characterization Of Porcine Periosteum

Periosteum is multipotent tissue responsible for cortical bone deposition and is important in fracture repair. Research indicates the periosteum is mediated by similar mechanical signals to those that mediate bone growth and remodeling. Therefore, biaxial mechanical characterization of periosteum can be very informative, indeed. This paper presents the results of the first such examination. The porcine periosteum herein has at least three distinct layers - a cellular layer, an elastin-rich layer, and a collagen-rich layer - the latter two providing structural integrity. Not surprisingly then, the general biaxial mechanical characteristics of periosteum resemble those of other collagen and/or elastin-rich membranes. That is, periosteum is non-linear, anisotropic, and transitions from an easily-extensible state to near-inextensibility over a narrow range of stretch, with the circumferential direction being the least extensible relative to the traction-free configuration. Tissues are qualitatively similar across all pigs and anatomical sites tested herein, suggesting one may somewhat indiscriminately pool periosteal samples from multiple pigs and multiple locations, within the limits tested herein, for a common parametric analysis. Tissue shrinkage was significantly more pronounced in the axial direction when removed from the bone, corresponding well to the dense population of elastin fibers oriented in that direction. Finally, a seven-parameter pseudo-strain energy function was investigated to model our data and found to fit well, but exhibited poor predictive capacity.