Why Non-Contact ACL Injuries Should Never Happen

It is time that you, the athlete, get a dose of reality so you can prevent a major injury.

I am by no means an expert in sports medicine, orthopedics, or physical therapy. What I am is a walking, talking encyclopedia of experience. And I am here to say that non-contact ACL injuries should never happen. In the wake of Teddy Bridgewater’s gruesome knee injury, it’s time we talked about why.

We strength coaches preach and beat our heads against the wall trying to get our athletes to take responsibility for their own wellbeing, but usually that only happens after something tragic has occurred. It is time that you, the athlete, get a dose of reality so we can prevent a major injury.

Get as strong as you can in your hips and legs, particularly your glutes and hamstrings. [Photo courtesy: Chris Holder]

The Role of the ACL

First, a quick anatomy lesson. The ACL is one of the ligaments of the knee that holds the lower leg and upper leg together. Its primary responsibility is to resist the forces that shift the bones front to back, like when you come to a quick stop from a sprint. As you plant your foot, tibia shifts forward. The ACL stops the lower leg from jetting forward and pulling the knee apart. In a strong, healthy leg, the ligaments, tendons, and muscles harmoniously jump into action, helping the athlete stop and distributing the overall force throughout the legs and hips. If the system of muscles and ligaments that operate the knee are all strong and healthy, the athlete comes to a safe, athletic stop.

Now let’s talk about when it all goes wrong. If you tear your ACL, you can expect to be on the mend for nine months. Where it can get ugly is that when the ACL ruptures, it can take other structures with it. Menisci and other ligaments of the knee often end up getting damaged in the process. In Bridgewater’s case, for instance, not only did the ACL go, but the entire knee dislocated. The news is reporting that his rehab will be longer than a year. That means multiple structures have been damaged. Due to the severity of his injury, it’s not unreasonable to think he may never play again.

Contact vs Non-Contact ACL Injuries

Car accidents, major falls, plane crashes, and significant collisions on the field are what we call contact ACL injuries. This is where an external object/person collides with the body, particularly the leg, and creates such a terrific impact that the structure of the knee cannot withstand the force. Think about bending a pencil until it snaps.

Non-contact ACL injuries happen without the big collision. For the purposes of this article, we are going to look at the two most commonly reported ACL rupture mechanisms:

First, consider the stop from a sprint mentioned above. One of the most common ways to rupture the ACL is when the athlete is in an upright position (hips in extension) with the knee slightly bent. This stop puts a tremendous load on the front of the leg (quadriceps) and that same forward force is exerted on the lower leg. The force becomes so large that the integrity of the knee falls apart, and the ACL is unable to withstand the strain.

The second is the version that I have seen the most. It is similar to the first in that it tends to be an athlete coming to an abrupt stop (as in a sprint stop or the landing of a jump). But this time, the knee itself tweaks in toward of the midline of the body and the knee buckles under the load. This injury is similar to the first, but with the additional rotational forces, more structures are compromised.

The Causes of Non-Contact ACL Injury

Both of these circumstances can be prevented if the athlete has an appropriate amount of strength. The first scenario results from two key factors:

First, the hips play a monumental role in stabilizing the entire body, particularly the legs and low back. The vast majority of the time, when scenario one happens, the athlete isn’t strong enough to sink their hips into the stop. So they extend the hips in order to avoid what their brain feels is a desperately weak position. But with the knee slightly bent and the hips extended, the hamstring is eliminated from performing its protective function for the ACL. The quadriceps contract forcefully, and due to body position, the hamstrings become almost relaxed. Because the hamstrings are shut down, the ACL is a sitting duck. If this athlete had the strength and confidence in their hips to sit down into the deceleration, the hamstrings would lengthen, the posterior of the body would help with the load, and the entire muscular system would step in to protect the ACL and complete the stop.

In the second scenario, the hip becomes primary reason the knee falls apart. Remember in this situation, the knee buckles inward as the force moves up the leg. This happens because the external rotators of the hip are weak, which allows force to travel up the leg instead of being dispersed throughout the system, so the hip buckles under the pressure. A weak gluteus medius is particularly at fault in the knee jetting in. The resultant shearing between the tibia and femur twist the ACL apart.

The Key to Preventing ACL Injury

So how can we prevent this from happening? Simply put, lift. Get as strong as you can in your hips and legs, particularly your glutes and hamstrings. Then you need to develop a degree of tolerance through controlled running drills. Change of direction work and sprint-based starts and stops in the offseason make your legs more tolerant to the demands of the regular season.

Because the hamstring and hip play such a large role in protecting the ACL, I program considerable work for both. And not only in the straight line fashion like squats and deads. We need to address the glute medes in a direct way, so multi-plane exercises along with alterations in technique with traditional movements will help armor the athlete.

The only way to do this is to be diligent in getting strong.

Where most of you make your errors is you don’t train year ‘round. Many of you think that if you crank away during your sport’s preseason, it’s enough to get you ready. But you start to de-train from your last lifting session in about 72 hours. That means, if you take more than three days off from training in a row, your body begins to take steps backward. Those steps accelerate with each passing day. And if we are talking about a three week break to hang out at home and go on trips, those 21 days are like 21 nails in the coffin.

The reason I am being so harsh about this is that I see it happen all the time. There was a three-year stretch during which my entire athletic department of 21 sports had zero ACL tears. During those three years, I had a student-athlete population that loved to train hard and did everything I asked, whether they were in my facility or home for the summer. I’ve also had years where my athletes were less than dedicated to their training, and my fall sport athletes weren’t as prepared after goofing off all summer. Within a few practices during training camp, the sports medicine room started filling up.

ACL injuries are preventable. But avoiding them requires unrelenting dedication to getting and staying strong. It’s completely within your power to never have to hear me tell you, “I told you so.”

More on injury prevention:

Are You Weak in the Knees?

Protect your athletes:

5 Injury Prevention Exercises to Build Bulletproof Athletes