A new study examines how ligaments fail, offering new insights into injuries that are not always easy to identify on scans.
As the University of Pennsylvania reports, a torn ligament is usually diagnosed on the basis of ruptures in the ligament´s collagen fibres, visible on a variety of scans. However, doctors also often treat patients with many of the symptoms of a tear, but whose ligaments don´t show this kind of damage.
So-called “sub-failure” injuries can lead to pain and dysfunction despite the lack of obvious physical evidence, but the mechanisms that lead to these symptoms happen on a microscopic level and can´t be detected by existing clinical tools.
In a study published in the Journal of the Royal Society Interface, the team from the University of Pennsylvania´s School of Engineering and Applied Science tested human ligament samples by stretching them until they tore, while looking at these microscopic features. Using a polarized-light-based system that can reveal the angles of collagen fibres in the tissue, the researchers showed how groups of neighbouring fibres changing their orientations in tandem prefigures the spots where failure eventually occurs.
According to the university, these insights could help identify regions of ligaments that are prone to tearing, and could eventually be incorporated into new diagnostic techniques or therapies. The research could also help explain the painful symptoms patients experience in sub-failure injuries.
The findings raise the possibility of particularly injury-prone “domains” — anomalous sub-regions within the tissue that arise from unique alterations of an individual´s anatomy. The presence and location of such domains might explain why different people respond to the same type of injury with different outcomes, the university said.