Lead Chief Investigator

Qing-Hua Qin Research School of Engineering, CECS, Australian National University

Project Title

Piezoelectric bone remodeling analysis by finite element method

Brief Description for General Publications

The bone that makes up our skeleton is a dynamically adaptable material. It, like any other living system, has mechanisms for repair and growth or remodelling, to feed its constituent parts and ensure that any materials needed for structural work are supplied to the correct area as and when they are required. It is found that the above bone functions are performed through three types of bone cells: osteoblast, osteoclast, and osteocyte. Osteoblasts are cells that form new bone and are typically found lining bone surfaces that are undergoing extensive remodelling. Osteoclasts are large, multinucleated, bone-removing cells. Their function is to break down and remove bone material that is no longer needed or that has been damaged in some way. The third cell type is the osteocyte. Osteocytes, called the bone “sensor cells,” are responsible for sensing the physical environment to which the skeleton is subjected. Many protoplasmic processes, or dendrites, emanating from the cell body characterize osteocytes. These cell dendrites form a communication network with surrounding cells, other osteocytes, osteoblasts, and possibly osteoclasts that passes the signals from the osteocytes that control the action of the osteoblasts and osteoclasts. These three cell populations, and numerous other biological and biochemical factors, coordinate their activities in a continuous process throughout our lives to maintain a strong, healthy skeleton system. The purpose of this project is to simulate internal bone modelling process induced by electric field or a medullar pin and to study potential applications of smart bone tissues to biomedical engineering. The simulation is based on a new bone modelling model we developed recently and a 3-dimentional finite element model given in the FE software ABAQUS. After the FEM methodology is firmly established, numerical calculations will be performed on a large number of practical examples such as bone remodeling process when a pin is inserted in a hollow circular bone cylinder or the cancellous bone remodeling under electromechanical field; to gain a full understanding of piezoelectric bone remodeling mechanisms. The solution of a hollow circular cylinder inserted by a pin can be obtained by decomposing the problem into two separate sub-problems: the problem of the modeling of a hollow circular cylinder of adaptive bone material subjected to external loads, and the problem of an isotropic solid elastic cylinder subjected to an external pressure. The inner and outer surfaces of the bone material are assumed to be unchanged. The calculation can be performed on the platform of ABAQUS. The investigation will address the basis of how external electric field can affect and control bone remodelling and adaptation process; how the physical nature of bone damage and its relationship to stress and electric fields experienced by the skeleton can be characterized. It is envisaged that this new research program will open a new direction of biomaterial science at this department, i.e. smart or intelligent bone materials and structures, thus providing a research framework for further development in this new area and the creation of fascinating and technically important challenges.