Reason: The dissertation contains material which we are actively seeking to publish.
until file(s) become available
Analyzing Biomechanics and Dynamic Signals Responsible for Tissue Adaptation in Mammal and Avian Bones
Osteoporosis is a common metabolic bone disorder characterized by low bone mass and microstructural degradation of bone tissue due to derailed bone remodeling process. A deeper understanding of mechanobiological phenomenon modulating bone remodeling response to mechanical load in a healthy bone is crucial to develop treatments for this bone remodeling disease by restoring bone integrity, and preventing further bone loss and fracture. Rodent models have been provided invaluable insight into the mechanobiological mechanisms regulating the bone adaptation response to dynamic mechanic stimuli. However, use of avian models may suggest novel insight into the mechanisms managing bone adaptation to dynamic load since the bird bones have some distinctive features to the mammal bones.
This dissertation sheds light on these aspects by means of assessing mechanical environment of cortical and cancellous tissue to in vivo dynamic compressive loading within the mouse tibia and chukar partridge tibiotarsus using microCT-based finite element model in combination with diaphyseal strain gauge measures. While the mouse tibial loading model showed that cancellous strains were lower than those in the midshaft cortical bone, cancellous strains were greater than those in the midshaft cortical bone for the bird tibiotarsal loading model. Sensitivity analyses for both the mouse model and the bird model demonstrated that the material property of cortical bone was the most significant model parameter. Despite the correlations between the computationally-modeled strains and strain gradients, and histologically-measured bone formation thickness at the mid-diaphyseal cross-section of the mouse tibia, no correlation existed between the modeled strains and bone formation measures at the mid-diaphyseal cross-sections of the bird tibiotarsus. A weak correlation found between the mid-diaphyseal strain gradients and bone formation thickness for birds. Further studies in this direction will enhance the interpretation of how the bone adaptation mechanism in a healthy bone is modulated to maintain bone integrity.