Cause, prevention of ACL injuries unclear
There has been a great deal of research on hormones and how they affect the strength of the collagen of the ACL, but results are not conclusive. Why female athletes have more ACL injuries and how to prevent these injures are still two major unknowns. Are the causes hormonal or structural, or is there some genetic component? More than likely, each of these factors is involved.
“Are the causes hormonal or structural, or is there some genetic component? More than likely, each of the these factors is involved.”
As for a genetic risk for ACL injuries, many of the young women I treat have relatives who’ve also torn their ACL. We don’t know whether the genetic component is expressed in the collagen, in weakening the actual ligament, the way the athlete lands, how her femur or tibia is made, or her structural alignment.
In addition, anatomy can play a part in an athlete’s risk for an ACL injury. For example, many female athletes have "miserable malalignment syndrome" - the combination of wide hips, thighs that turn inward from the hip, knock knees and flat feet, which may contribute to ACL problems.
In the last five years, several studies have focused on the issue of prevention. Multiple groups of researchers around the country have tried to teach female athletes how to land, run and jump better. What we have found is that female athletes don’t like to bend their knees when, for example, they come down from a rebound in basketball. They like to stand very upright.
These studies have focused on retraining the muscles that function a certain way. There’s been some encouraging data, but we need much larger studies conducted over a longer period of time. Overall, retraining is a great idea because if it helps even one person, it’s wonderful. Retraining is not invasive or harmful.
We’re a long way from preventing ACL injuries, but early training could also help. It’s easier to teach children when they’re young, before they develop motor memory. And the focus on just one sport should be reconsidered. If you play in many different sports, you learn to use different muscle groups.
Thirty years ago, an ACL tear was a career-ender for many athletes. Today, with the improvements in surgery and rehabilitation, many can get back into the game. But what concerns doctors in sports medicine is the long-term problem of arthritis that develops in the knee.
One recent study followed elite female soccer players 10 years after surgery for ACL injuries. More than 80 percent of these women, all in their early 30s, had radiographic changes of arthritis. Another study looked at a group of male and female athletes seven years after ACL surgery. More than 50 percent had arthritis, and only about 50 percent were still participating in sports at the same level.
A new surgical technique - anatomic ACL double-bundle reconstruction surgery - has the possibility of preventing these problems, but we don’t yet have long-term data on its effectiveness. The surgery is performed at only a few centers in the United States, including the University of Kentucky, because it’s more technically challenging. I do it only in select cases, such as when the ACL fails following previous surgery.
The ACL is made up of two bundles of ligaments. Typically, surgeons have replaced the injured ligament with one bundle. This new procedure replaces both. Laboratory studies have shown that this new technique more closely reproduces normal knee motions than the traditional, more common single-bundle ACL surgery. The hope is that if we reproduce the normal anatomy of the knee better, we are going to increase the chances that the knee movements will work better and the patient won’t develop arthritis.
“There’s a misconception... that injured athletes can go back to playing sports at pre-injury level after treatment.”
The majority of patients we see want to return to playing sports. If they don’t have surgery, they won’t be able to do that. However, I tell all of them, surgery is the easy part. The hardest part is mental and the will to be committed to rehabilitation.
Unfortunately, there’s a misconception in the public that injured athletes can go back to playing sports at pre-injury level after treatment. The fact is, only 50-80 percent make it back to that level, and then only after a year of rehabilitation and therapy.
Yet the first question the parents, the coach and the athlete ask is, "When can she return to playing?" Parents need to think about what will happen to the athlete in another 10 years. If she’s had numerous ACL injuries, they should have a conversation with her about whether she should return to the sport. As a physician, it’s my job to educate everyone involved that not all of the athletes with ACL injuries will do well.
Dr. Johnson is professor and chairman of orthopaedic surgery and medical director of sports medicine.