Based on the medical observation that torn Anterior Cruciate Ligaments (ACLs for short) often don’t heal, common wisdom is that the ACL simply cannot heal. But there is a crucial difference between “can’t” and “don’t.”

A few researchers have looked at why the ACL doesn’t often heal on its own, and the answer, according to one doctor, is as simple as this: the torn ends of the torn ligament aren’t able to get close enough to knit themselves back into one.

Looking at torn ACL tissue under the microscope, Dr. Murray discovered that the injury tries to heal on its own—cells proliferate, blood vessels grow—but the ligament ends never join. When most ligaments tear, a blood clot forms, creating a temporary scaffold for cells to migrate onto, but in ACL tears, fluid in the knee joint washes the clot away.

via Children’s Hospital Boston

This makes a lot of sense if you think about it.  If you got a paper cut, for example, the wound would eventually heal.  The skin grows back together over time.  As long as there is contact between the skin on either side of the cut, the skin will grow back together.

If you tear a ligament, as long as you can get the pieces to get close enough together, it’ll heal.  If you have a knee that’s twisted out of alignment, torquing the ACL into a compromised position, it’s only a matter of time before you blow it out completely.  Unless you fix that torqued position — even with a gel to help ACL heal — it seems like you’d just be waiting to blow it out all over again.