A study comparing images of the knees of people who had and hadn’t suffered injury to their anterior cruciate ligaments, suggests that those who tore their ACLs were more likely to have a smaller ligament than do similarly sized people who have never injured a knee.
Researchers calculated the total volume of the ligaments based on magnetic resonance images of human knees. The ACLs among those with previous injuries were, on average, about 10 percent smaller than were ACLs among those without an injury.
Researchers caution that the retrospective study does not mean that a smaller ACL will necessarily result in injury. Instead, they say the research offers more clues about the variety of factors that appear to be contributors to ACL injury, such as activity level, neuromuscular co-ordination, gender and muscle strength
In this group of participants, weight was the strongest predictor of ACL volume. “If you compared two people of the same weight, based on our data set, we would expect the injured person had the smaller ACL,” said Ajit Chaudhari, Assistant Professor of Orthopedics at Ohio State University and lead author of the study.
Knowing that the knee’s anatomy can influence susceptibility should help researchers who are trying to ascertain why ACL injuries occur and who is most likely to experience these injuries, Chaudhari said. Most study results guide the assignment of a percentage of risk to one or more factors associated with torn ACLs, but to date no research had looked solely at the size of the ligament in injured and non-injured knees.