Micromechanics of the Vertebral Body
People: Tongge Wu
There are around 700,000 vertebral fracture cases in the US every year, which are associated with a medical cost of $14 billion. In a long term perspective, a vertebral fracture could lead to a second vertebral fracture or a subsequent hip fracture. Some evidence even shows that for the elderly, a vertebral fracture could increase the mortality rate. However, some fundamental questions remain not answered in the vertebral fracture mechanism. For example, how bone micro-architecture affects the bone strength independent of the material properties and vice versa; why in experiments some vertebral bodies showed a significantly reduced micro-architecture while being able to maintain the same strength compared to normal vertebral bodies; how the vertebral fracture mechanism differs between monotonic loading and cyclic loading.
Using high-resolution micro-CT scanning of the vertebral body and finite element method, we are able to investigate the stress/strain distribution, fracture location, fracture patterns within the vertebral bod otherwise impossible in an experimental setting. One goal of this research is to elucidate the effect of ionizing radiation on the micromechanics of the mouse vertebral bodies. Inspired by previous results where we observed that ionizing radiation could lead to a reduction in the mouse vertebral body morphology but not the monotonic strength. Using the high-resolution nonlinear FE model, we could study the fracture process step by step and investigate how the ionizing radiation affects the micro-mechanics behavior of the mouse vertebral body, hence, answer the question of how the mouse vertebral body maintains the strength with a diminished bone morphology.
Another goal of this research is to illustrate the fracture process in the mouse vertebral body under cyclic loading (i.e. fatigue) and compare it with the monoatomic fracture. To achieve this goal, we have two subgoals where the first one is to accurately characterize the material fatigue properties of the trabecular bone, which is the main component of the mouse vertebral body; the second is the actual comparison between the failure pattern in the fatigue loading versus in the monotonic loading, and the failure pattern in the fatigue loading on normal mouse vertebral body versus on the mouse vertebral body with reduced micro-architecture.< Back to previous page