Wow, this Penn State study is amazing. I don’t think that I’ve ever considered the possibility that playing sports causes significant microtrauma to our ACLs and that potentially sets us up for an ACL injury.
I’ve always assumed that when one tears one’s ACL, it’s a situation where the force of injury is more than the strength of the native ACL. If this rabbit study actually mimics the human response, perhaps there is some way to treat or prevent microtrauma to reduce the risk of ACL injury, especially in female athletes.
Here’s a brief excerpt:
In the study, which was published in the Journal of Orthopaedic Research, researchers placed ACLs from deceased male and female rabbits in a custom-made bioreactor that simulated the conditions of a living animal but allowed direct observation and measurement of the tissue. Next, they applied repetitive forces to the ACLs that mimicked those that would naturally occur during activities such as standing, walking and trotting and measured the expression of genes related to healing.
In male samples, the team found that low and moderate applied forces, such as those that would occur during standing or walking, resulted in increased expression of anabolic genes, which are related to building molecules needed for healing. By contrast, larger applied forces, such as those that would occur with repetitive trotting, decreased expression of these anabolic genes. For female samples, however, the amount of force applied did not influence the level of anabolic gene expression.
“Some studies have found that the overall effect of estrogen on ACL injury is negative,” Paschall said. “Specifically, studies have shown that human women are more likely to tear their ACLs during the preovulatory phase, when estrogen levels are high, than during the postovulatory phase, when estrogen levels are low.”
She said the team plans to further investigate the role of estrogen on ACL injury.
Read the complete article on the Penn State website: “Females less likely to heal from ACL injuries than males”