Friday, September 18, 2009

Tech To Examine the Mechanics of Knees

Raffaella De Vita (above) will take a look at the mechanics of knees for Tech^

A team of Virginia Tech engineering researchers has won a $300,000 National Science Foundation grant to study knee ligament sprains at the micro-mechanical level.

Principal investigator Raffaella De Vita, an assistant professor in the engineering science and mechanics department and director of the Mechanics of Soft Biological Systems Laboratory, will examine the role of the structural components of knee ligament in sprains by combining micro-mechanical models, molecular models, biological and mechanical experiments.

Previous biomechanics studies focused on quantifying the macro-mechanical properties of ligaments, such as tangent modulus, tensile strength, and ultimate strain. Yet, little is known of their response to mechanical stimuli that lead to partial and complete ligament failure.

The study is expected to clarify micro-structural changes, such as the level of collagen crosslink, associated with partial and complete tears, De Vita said. The study will focus on the most common orthopedic injuries, such as those caused by when the knee is forced beyond its normal motion range, such as in a fall, or when the knee is impacted during a vehicular accident or participation in sports such as football. These injuries can consist of a slight over-stretch, a partial tear, or a complete disruption of the ligaments.

The study will involve rat specimens of similar age and sex type, but split into two groups--one fed a diet of sweet peas and the other a lethargic diet. Diet affects the crosslinks in collagen, which is the primary makeup of ligaments, De Vita says.

Harvested ligaments will be subjected to lab stress tests and their deformation observed by using a special high-speed camera. Once completed, the research findings could lead to the creation of replacement grafts and biological scaffolds for damaged ligaments. The results also will guide the design of braces or stretching routines to help prevent damage during stressful activities that otherwise would lead to ligament sprains. Expected research benefits are not solely limited to knees.

“The research findings will contribute to understanding the failure mechanism of more complex biological soft tissues such as, for example, skin and arteries” that are comprised of collagen, said De Vita.

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