How a Leading Orthopedic Surgeon is Trying to Prevent ACL Injuries

Andrew D. Pearle, MD, a leading orthopedic surgeon at HSS discusses the increase in ACL injuries among teenage athletes and how they can be prevented

Andrew D. Pearle, MD

Andrew D. Pearle, MD

Jasper Nusbaum

Dr. Andrew D. Pearle is a board certified orthopedic surgeon at Hospital for Special Surgery, specializing in sports medicine. Dr. Pearle’s clinical interests include arthroscopic and robotic surgery of the shoulder, knee, and ankle. He is Director of the Computer Assisted Surgery Center at HSS and Editor-in-Chief of the Orthopedic Journal Techniques in Knee Surgery. Dr. Pearle and a team of other orthopedic surgeons are currently developing an app geared to preventing ACL tears.

1. How would you describe what you do?

I am an orthopedic surgeon at the Hospital for Special Surgery in NYC.  I specialize in sports medicine and knee surgery in particular. I am one of the team docs for the NY Mets as well as the newly established New York professional rugby team (Rugby Union New York.)  I am also the medical director of HSS’ newest and largest outpatient center which is located in Westchester, where I see patients once a week.

I am also a member of the ACL study group, an international group of surgeons and researchers who meet every two years to try to improve ACL surgery and to promote ACL injury prevention.

2. ACL repair/reconstruction is one of your specialties. What percent of your clients come to you with torn ACL’s? How many surgeries do you perform each week?

I perform 15-20 surgeries per week and about 20% of my surgeries are ACL reconstructions (particularly in the winter, when I see too many ski injuries resulting in ACL injuries.)

3. Are you seeing a rise in torn ACL’s among teenagers? Are there any patterns or trends (male vs female, athletes vs non-athletes, or a specific sport?)

Unfortunately, ACL injuries are an epidemic in high school and college athletes.  It has been shown that there has been a 2% increase in the number of ACL tears in kids 6-18 years old EVERY year over the past 20 years.  Females are estimated to have a 2-8x higher risk of tearing their ACL than males. The most dangerous sports for the ACL in high school boys are:  1. Football 2. Lacrosse 3. Soccer and 4. Basketball. For girls, ACL injury risk is highest in: 1. Soccer 2. Basketball 3. Lacrosse and 4. Field Hockey.

The numbers are sobering.  Research has shown, for example, that a high school female soccer player has a 1.1% chance of tearing her ACL every season.  If this girl is a 3 sport athlete, and plays basketball (0.9% chance of tearing her ACL every season) and lacrosse (0.5% chance of tear her ACL every season), she has a 2.5% chance of tearing her ACL over the course of the school year (1.1% + 0.9% +0.5%.)  If she plays these sports for 4 years, she has a 10% chance of tearing her ACL during her high school years (assuming she takes the summer off from sports.) Now imagine this athlete only plays soccer and plays year-round throughout high school. This female athlete would have a 1.1% risk x 4 seasons or 4.4% chance of tearing her ACL per year and 17.6% chance of tearing her ACL at some point in high school!!!

4. Are torn ACL’s preventable?

It has been estimated that 50%-70% of ACL tears are potentially preventable. This is also sobering because we are not doing enough to prevent these injuries.

The concept is that a large percentage of ACL tears occur during “non-contact” events.  An athlete will be slightly off balance, cut sharply or land awkwardly, and tear their ACL.  Various landing and cutting patterns put the ACL at risk. There are prevention programs that teach kids to start, stop, cut, and land using strategies that protect the ACL.  These strategies, or movement patterns, also have the added benefit optimizing biomechanics so that kids are stronger, faster, and more stable – ie. more athletic. The concept is to jump, stop, and move with your knees directly over year feet so that the knee does not collapse inward.  This requires strength and mobility in your hips so that the strong muscles of the hips and core can help soften the torque on the knees.

5. I understand you are creating an app to help prevent ACL injuries. Could you describe the app and explain how this came about?

It is so frustrating to know that such a large percentage of ACL tears are preventable and that kids can become better athletes by performing the prevention training.  There are warm-up exercises that can help with ACL prevention and organizations such as FIFA have endorsed warm up prevention programs (like the FIFA 11 Injury Prevention program.)

I have coached Rye Town Youth Football for the past 5 years and I realize how difficult it is for a coach to ensure that all the kids do a warm up properly.  Because of the difficulty inherent in getting kids and coaches to be disciplined about doing their ACL prevention exercises, I was looking for a new approach.

The New York Times published an article a couple years ago about a “7-minute workout” – 12 high intensity exercises each done for 30 seconds that provides a scientifically proven effective full body workout  

The beauty of the workout is that it requires minimal equipment and uses only bodyweight.  It became a sensation and apps that help people through the 7-minute workout are constantly among of the most popular fitness apps in the Apple app store.

My idea was to design a 7 minute ACL prevention workout using the same strategy: 12 scientifically proven exercises to help prevent ACL tears that are done for 30 seconds each in rapid succession.  The app can be given to middle school and high school athletes and compliance can be tracked. Improvement in kids landing and cutting strategies can also be testing with some of our motion capture systems at HSS Westchester.

6. Is the app intended solely for prevention or is there also a recovery aspect as well?       

At this point, the app is designed for ACL “protection.”  The hope is that it will prevent a percentage of ACL injuries and promote awareness about this topic.  It will not prevent every ACL injury and is not designed for rehab after ACL reconstruction.

Preview of Dr. Pearle’s app, Knee G.


7. How close is the app to being finished? When will it be on the app store?

We hope to have the app finished by this spring or early summer.  Stay tuned. We plan to call it Knee G (short for Knee Guardian.)