New approaches to cancellous bone bio-modeling.

The purpose of our research is to develop a model of cancellous bone that would allow us to forecast the changes in this structure under various mechanical forces and to simulate the dynamics of the cancellous bone behavior under these circumstances. At the same time, the suggested model will allow the measurement of the tension/forces applied onto the bone structure, with the purpose of comparing these with the in vitro values, identification of the areas with increased trauma risk, and simulation of the behavior of cancellous substance under different mechanical stimuli, which affect the growth and aging of the bone, as well as to study the materials used in endoprostheses. Two groups of methods have been used for this purpose: micro-anatomical methods - for the visualization of bone structures, and bio-mathematical methods (finite element method) - for the modeling of these structures. The micro-anatomical studies were performed on a group of six bone items, from which 12 samples were harvested from the femoral head and neck, from corpses of both sexes and of varying ages, whose death was not due to specific pathological states or which could regard the bone itself. The obtained results have allowed us in identification of dependency relationships between the microscopic structure of the trabecular bone and its mechanical properties, as well as for the elaboration of bidimensional reconstructive and analytic models of the cancellous bone, which would further allow detailed representation of samples of cancellous bone that are big enough to supply macroscopic information. The conclusions of the present research have illustrated the usefulness of using the finite element method in the study of the mechanical behavior of spongy tissue, thus opening large perspectives in approaching the issue of the behavior of this tissue.