Researchers at Washington University in St. Louis have constructed algorithms that could be used to discern areas of tendons, muscles and bones more vulnerable to injury than others.

Although the technology is not ready for patients, it could uncover tiny sprains and tears that tend to go unnoticed before succumbing to greater injury and researchers say it could one day be used for injury prevention.

"Tendons are constantly stretching as muscles pull on them, and bones also bend or compress as we carry out everyday activities," says senior investigator Stavros Thomopoulos, PhD, a professor of orthopedic surgery at WU. "Small cracks or tears can result from these loads and lead to major injuries."

Thomopoulos and his colleagues stretched tissues and examined their appearance under stress and distortion. They started using textiles, and then advanced to animal testing.

First author John J. Boyle, a biomechanical engineering graduate student, developed the algorithms through a combination of basic mechanical engineering and image analysis technology.

"If you imagine stretching Silly Putty or a swimming cap with a picture on it, as you pull, the picture becomes distorted," says Boyle. "This allows us to track how the material responds to an external force."

Boyle describes, using the example of an experiment they performed using plastic wrap, that pulling and stretching of any material eventually leads to tears and the places that tear first have a slightly weaker quality than those that resist.

"Understanding how these tears and cracks develop over time therefore is important for diagnosing and tracking injuries," says Dr. Thomopoulos.

While this method for understanding injury prevention isn't new, it's 1,000 times more accurate than the old algorithms at quantifying stretches surrounding the seemingly negligible tears and cracks, according to researchers.

The other of the two new algorithms excels at locating the likely places where injuries could form.

Guy Genin, PhD, professor of mechanical engineering and co-senior investigator on the study, says that the algorithms are likely to help scientists understand how the forces that react against human tissues manage to break them down in the long run.
