Researchers in engineering, health search for new ways to detect bone fragility, prevent fracturesBy John Roe Faculty of Engineering
Engineering and health experts at the University of Waterloo are collaborating on research that may lead to breakthroughs in preventing a serious, all-too-common injury - broken bones.
Their findings could prove especially important to elderly people typically more prone to falls and hip fractures. In fact, understanding the mechanics of how bones weaken over time could help serve the needs of the aging population in many parts of today’s developed world.
"We’re trying to put pieces of a puzzle together to understand the fundamental fracture mechanisms of bone and how these mechanisms degrade in aging and disease," explained Dr. Thomas Willett , who applies engineering principles to the human body. "How does bone fracture? How does it resist fracture? How does this change with aging and disease?"
As one piece of a complex picture, Willett and other members of the research team, including PhD students Daniel Dapaah of engineering and Daniel Martel of kinesiology, and collaborator Dr. Andrew Laing, a kinesiology professor, recently developed an innovative testing method to simulate the impact a real fall would have on the fracture behaviour of human bone tissue.
Most previous studies into bone fragility haven’t done that. Conducting tests as true to life as possible enabled the team to better understand the actual toughening mechanisms that inhibit or slow the growth of cracks that lead to bone fractures.
Part of an ongoing project by researchers in systems design engineering and kinesiology and health sciences at Waterloo, the study looked at the micro-damage process zone, which forms around cracks in bones. It’s the role of the micro-damage process zone to inhibit or slow the growth of cracks that might result in actual breaks when the bone is loaded in a fall.
The researchers extracted specimens from the thigh bones of five human male cadavers and cut razor-sharp notches in them to approximate what happens when a crack exists. Half of the sections went through a conventional slow-loading rate test. The other half were subjected to a higher rate of loading to mimic what the bone tissue might experience in a fall.
Understanding the ’mechanisms of disease’
The results were revelatory, yielding a much clearer picture of the significant impact on bone cracks and the likelihood of breaks when people fall. The size of the micro-damage process zone was 42-per-cent smaller in the group subjected to a higher loading rate than in the other group. This dramatically smaller size was associated with brittle, unstable fracture behaviour and reduced resistance to possible breaks.
"When we understand the mechanisms of disease or greater bone fragility, then we can propose ways to detect, prevent and treat fragility, and maybe prevent some fractures," Willett said.
The research was funded by the University of Waterloo Network for Aging Research and the Canadian Institutes of Health Research.