The development of a small animal model for assessing the 3D implications of loading on bone microarchitecture
Year: 2011
Type: dissertation
Abstract: It is well established that bone is capable of adapting to changes in its environment; however, little is known regarding how environmental stimuli, specifically loading, are associated with the internal 3D microarchitecture of cortical bone.The aim of this thesis was to develop a small animal model that can be used to experimentally test hypotheses regarding bone adaptation.High resolution micro-CT was validated and employed as a novel method for the visualization and quantification of rat cortical bone microarchitecture in 3D.The use of this imaging method allowed for the measurement of primary vascular canal orientation in 3D, which had never been achieved before.Using this measure along with an immobilization model for unloading allowed me to test how loading is associated with the orientation of these vascular canals.Normally ambulating rat bones (from 10 female rats) had a canal structure that was 9.9° more longitudinal than their immobilized counterparts.This finding that loading has an effect on primary canal orientation brought to light the need to induce remodeling and therefore, secondary vascular canals, in the rat to increase its novelty as a model for looking at bone adaptation.Remodeling was induced by increasing the calcium demands of female rats, either through a calcium restricted diet (n=2) or pregnancy and lactation coupled with a calcium restricted diet (n=2).Mean cortical thickness for the calcium restricted rats and the pregnant and lactating rats that were on a calcium restricted diet were 622 µm and 419 µm, respectively.The mean BMU count for calcium restricted rats seemed to be higher than that of the pregnant and lactating rats; however, the calcium restricted rats seemed to have a lower BMU density.Once this full-scale study is executed the rat will provide a more representative model for studying human bone adaptation.iii ACKNOWLDEGEMENTS I am grateful for the contributions of numerous individuals and institutions that have made this thesis possible.I would like to start off by expressing my greatest thanks to my supervisor, Dr. David Cooper for providing me with the outline of a great project and the direction to complete it when needed.Dave, not only did you bring me to the dark side by deeming me worthy of being your first student at the University of Saskatchewan but you have also instilled in me your enthusiasm for research.I would also like to thank the additional members of my advisory committee, Drs.Saija Kontulainen and Valerie Verge for their insight and assistance over the years.This thesis would not have been possible had it not been for the generosity and collaborative efforts of Drs.Jarkko Jokihaara, Olli V. Leppänen, Teppo L.N. Järvinen for providing me with the specimens employed in Chapters 2 and 3.Not to mention their feedback regarding the manuscripts that make up these two chapters.I would like to thank the students and staff of the Department of Anatomy and Cell Biology for their friendship, support and pranking
Author: Hayley M. Britz
Language: English
Subfield: Orthopedics and Sports Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2100413924