BME Seminar Series: Christopher J. Hernandez, Ph.D.

The Contribution of Bone Remodeling to Failure Processes in Cancellous Bone

Abstract:

Bone remodeling is the primary process of modifying bone volume and structure in adults and is believed to be the primary process of removing old or damaged bone tissue from the skeleton. The total amount of bone remodeling in the skeleton can be measured in blood or urine and is a predictor of fracture risk independent of measures of bone size and mass, suggesting that bone remodeling itself can influence the ability of bone to resist fracture. Bone remodeling occurs at discrete events within the bone structure known as basic multicellular units and is currently only measured indirectly through analysis of two-dimensional sections of bone placed on microscope slides. Here I present a series of studies using materials testing and a novel sub-micron scale, fluorescent three-dimensional imaging to study the bone remodeling process and the formation of microscopic cracks and other tissue damage in bone. Three-dimensional imaging at the sub-micron scale makes it possible to make more precise measures of bone formation and resorption than are possible with traditional two-dimensional sectioning and allows us to determine how drug treatments alter the size and shape of individual resorption cavities in cancellous bone. Additionally, we determine how microscopic cracks and other tissue damage caused by loading in vitro are spatially related to the discrete instances of bone remodeling. Our results suggest that regulation of the number, size and morphology of individual remodeling events can be regulated by osteoporosis treatments and appears to influences failure processes in cancellous bone.