Interdisciplinary Seminar in Nonlinear Science

Title: How to Find out when Bones may Break
Speaker: Gemunu Gunaratne
Speaker Info: University of Houston
Brief Description:
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Osteoporosis is one of the major health problems in western societies. Since therapeutic agents used to reduce bone degradation have adverse side-effects, it is essential to be able to reliably identify subjects requiring therapy. Bone density, which is currently the principal means for detecting osteoporosis, is known to only partially account for bone strength. It has been well-established that factors such as the levels of connectivity and anisotropy of the inner porous segments of bone (trabeculae) play a significant role in determining the strength of vertebral and other bones. Reliability of diagnostic tools can only be enhanced by properly accounting for the consequences of these multiple facets.We have used a mathematical model consisting of disordered cubic networks of struts and nodes to represent porous bone. The freedom to implement independent changes provides means to deduce those factors which cause largest reductions in bone strength. It was found that the principal reason for age-related bone degredation is the increasing inefficiency in load transmission, and that this is caused by longer fractures in a bone sample. Ideas from fracture mechanics and percolation theory can then be used (1) to derive a new expression relating the strength and density of a sample, and (2) to deduce a new diagnstic for osteoporosis. The latter depends on vibrational responses of a bone sample. These conclusions have been confirmed using computer models built from digitized images of bone and/or data from human bone samples.
Date: Friday, February 27, 2004
Time: 2:00PM
Where: Tech M416
Contact Person: Hermann Riecke
Contact email: h-riecke@northwestern.edu
Contact Phone: 847-491-8316
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