Biaxial Investigation Of Periosteal Mechanics

Limb lengthening procedures are used commonly to correct limb length discrepancies. Current methods in limb lengthening require a distraction of 1 mm per day using an external fixation device. Although the underlying mechanisms of new bone growth have been studied and discussed extensively, they remain not fully understood. It is thought, however, that mechanoreceptor cells of the periosteum play an important role. In an attempt to understand the contribution of periosteum, the biaxial mechanical properties of the periosteum are studied. Freshly excised porcine periosteum was used to investigate the effects of preload on the material symmetry, and the effects of mechanical boundary constraints on the remodeling of the periosteum in vitro. The mechanics of porcine periosteum show a greater influence of elastin in its in vivo state, and is shown to be highly stressed contrary to other findings. Tissues were cultured in a relaxed configuration, a stretched (in vivo) configuration, and a dynamically loaded condition and show trends of increased extensibility over time. A 5-parameter pseudo-strain energy function was employed to characterize the mechanical properties of porcine periosteum. The model was found to fit well for periosteum tested from a relaxed preconditioned state, but was unable to predict corresponding in vivo and proportional responses.