Coalition Aims to Halve ACL Injuries in High School Athletes

Andrew D. Pearle, MD

Anterior cruciate ligament (ACL) injuries pose a major threat to high school athletes. The recovery process is slow, generally taking 6-9 months, and even then, some athletes are unable to return to their sport. This is a particular issue for female athletes, who have an elevated risk compared with males. A female playing multiple sports is estimated to have a 10% risk of tearing her ACL over her entire high school career. To address this issue, Hospital for Special Surgery (HSS) and the Aspen Institute have partnered with nine other organizations to form the National ACL Injury Coalition. Medscape spoke with Andrew D. Pearle, MD, chief of sports medicine at HSS, to learn more about this coalition and how ACL injuries can be prevented.

Which sports pose a higher risk for ACL injuries?

Typically, team sports are higher risk, where there are sudden changes of speed or direction (ie, cutting sports). Chief among them is soccer, and women's soccer is probably the most dangerous sport for ACL noncontact injuries. Other sports include basketball, lacrosse, field hockey, and, of course, football; however, football is slightly different because it is a collision sport, so many of the ACL injuries in football — though certainly not all of them — are contact injuries vs the noncontact injuries that we see in a lot of sports.

Are younger athletes more at risk for ACL injuries?

I think a big part of ACL injury risk is exposure, meaning how often someone plays a sport. A working professional in their mid-20s who graduated college may play basketball once or twice a week. Compare that with someone at the high school or college level, who is practicing four times a week and may have two games a weekend. A lot of the injury risk is an exposure phenomenon: how much of a sport you play. People tend to play fewer cutting sports as they leave high school or college venues.

Why do female athletes have a higher risk for ACL injury?

While there are no differences structurally between a male and female ACL, females tend to have more ligament laxity, compared with males. There are also differences in muscle strength as well as activation when jumping; females show lower muscle activation when landing, compared with males. Females also have wider hips than males, all of which contributes to an increased risk for ACL tears.

What was the driver behind forming this coalition?

I got into this because as an ACL surgeon, I'm sick of operating on kids, knowing that a lot of these injuries are preventable. We have over 20 years of data showing that certain exercises can help prevent ACL injury. These exercises, called neuromuscular training, help build muscle memories that optimize athletic movement to make it safer and efficient. Some examples of these exercises include squats, lunges, and landing stabilization exercises like skater hops and bounding. The focus of these exercises is technique and form, rather than adding more weight. Neuromuscular training can drop the risk for ACL injuries in certain sports like soccer by 50%-80%. But it doesn't only prevent ACL injuries; it lowers the risk for all-time loss from injury by one third, and reduces ankle sprains and head injuries because you're moving with more control.

We know what exercises to do, when to do them, what sports most benefit from these exercises, and what ages to target. But the reality is that this is a behavioral modification, and there are lots of different stakeholders who must come together for us to really make an impact.

Is there special equipment required for these exercises?

HSS developed a free mobile app called RIIP Reps, which stands for Reduce Injuries, Improve Performance. It consists of 7-minute sessions that are to be done four times a week throughout the season. The training sessions can be done in a small space and require no special equipment. Some of these exercises are common in warmups, but this program is designed to be done outside of the practice session. The reason that's important is because coaches have a very limited amount of practice time or field time, and they often don't want to interrupt practice for dedicated neuromuscular training programs. While you can do these exercises as a warmup, players also can do it at home like homework and then come to practice and focus on skill training.

What are the goals of this coalition?

One goal is to raise awareness about ACL injury prevention, and then offer schools, teams, parents, and players a toolkit so they know how to do these exercises and what the resources are. The RIIP Rep app is part of the toolkit, and other neuromuscular training programs are also included. All of these resources are available on the coalition's website.

An aspirational goal would be to reduce noncontact ACL injuries by 50% in the high school population. We envision a world where people are aware of the short- and long-term ramifications of knee injury, and a culture where people are trying to do neuromuscular training to live healthier lives.

Are there other best practices to prevent ACL injuries?

With travel leagues, people are playing more games, and I think that's why we're seeing a rise in ACL injuries. In girls, the chance of tearing your ACL is nine times higher in competition as opposed to practice. For boys, the chance is six times greater in competition. It's a very sensitive issue because there is a whole industry around this, but maybe kids should not be playing as many games. My son plays on a travel lacrosse team in high school, and he typically played four games in 1 day during tournaments. You wouldn't have a college team or a professional team play four games in 1 day, so why are high school teams and travel teams doing it?

With travel teams, younger players can be playing a sport year-round rather than just for a season, which further increases risk for ACL injury. For example, a player on a girl's high school soccer team has a 1.1% chance of tearing her ACL every season; over 4 years, that becomes a 4.4% chance. But if she's playing year-round, she has a more than 16% chance of ACL injury during high school. So, maybe kids shouldn't be playing one sport, especially if it's high risk, all year round. Instead, play softball or something else in the spring that is not as high risk.

Are there long-term consequences to ACL injury?

ACL injury is a bad injury to have, with typically almost a year of recovery. Most people — not everybody — go back to sports, but what they don't know is the downstream consequences of ACL injury. Fifteen years down the road, about 50% of people will have arthritic change, and it can be debilitating. For a high school athlete who tears their ACL, they are looking at arthritis in their 30s, which has a profound impact on life.

So, just as schools are supposed to build lifelong learners, we would like to build lifelong athletes. We want to protect the heads and the knees and make sure that people can engage in sports in their 30s, 40s, 50s, and beyond.

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