Research Projects: Bipin Pai

Fatigue Analysis of Bones

My current research interests include the study of human bone, especially the human femur bone has attracted a lot of attention lately, because certain types of fractures such as micro-fractures are very common among athletes in several sports, joggers, ballet dancers and soldiers. One common theme among all the individuals named above is that they train repeatedly using the same bones and muscles which can cause bone and muscle fatigue, very similar to engineering materials that are subjected to repeated loadings. Failure due to fatigue has been studied extensively with engineering materials such as aluminum and various types of steels. One reason why not much has been studied about the bone is that the bone has inconsistencies in terms of its composition. Bone consists primarily of two types: the cortical bone and the trabecular or cancellous bone. Cortical bone represents nearly 80% of the skeletal mass, it is compact, and has been shown to be very resistant to bending and torsion. It provides strength where bending is undesirable such as in the middle of long bones. Trabecular bone is less dense and represents only 20% of the skeletal mass. This bone is also very elastic and has a higher turnover rate than the cortical bone. It is found in the epipheseal and metaphysal regions of long bones.

The center of the bone contains marrow where new red blood cells are formed. My interest in this project is also because I have worked with the study of red blood cells in various environments during my Ph.D. thesis and also for a few years following my Ph.D. The renewal of bone is responsible for bone strength throughout our life. Old bone is removed through resorption and constantly replenished by new bone through formation. This process of resorption and formation is known as bone remodeling. Remodeling of bones happens very often, especially in athletes. The bone teaches itself to renew and form in certain areas depending on the constant loads that certain bones are subjected to repeatedly. Although the trabecular bone represents only 20% of the skeletal mass, it represents 80% of the bone surface.