My niece wrecked her knee in gym and the doctor said it was a torn ACL. I had a torn ACL not long ago, but my niece is only 10. How can that be?

The anterior cruciate ligament or ACL is one of the most important ligaments in the knee. Ligaments are thick fibrous tissues that hold bones together. A torn ACL is a relatively common sports injury but can happen through other means, like a fall.

Torn ACLs are becoming more common in children as they participate in more sports and in more athletic competitions, as well as in regular play. Surgeons have had to repair torn ACLs in children as young as three years old.