5 Things You Didn’t Know About ACL Injury

We’d all like the season to go out with a bang, but sometimes it goes out with a pop. That pop is your anterior cruciate ligament, commonly known as your ACL, and it’s every athlete’s least favorite sound. The ACL is the most commonly injured ligament in the knee, and tearing it is bad news.

The good news, though, is that there are ways to decrease the risk of an ACL injury. By learning more about this tiny but notorious ligament, you can keep your knees safe and your game on.

Here are five things you might not know about your ACL.

1. The ACL is one of four important ligaments that hold your knee together

The four ligaments of your knee provide stability to the joint and prevent your knee from moving in ways that could hurt you. Each ligament has a name that’s derived from where it is and what it looks like.

At the front of your knee is the anterior cruciate ligament or ACL, and it sits right behind your kneecap. This ligament has a buddy at the back of the knee called the posterior cruciate ligament or PCL.

The ACL and PCL work together to restrict the movement of the knee so that it doesn’t flex too far forward or too far back. They’re called “cruciate” ligaments because, taken together, they form an “X.”

On the sides of your knee are two more ligaments called the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). The LCL is on the outside of your knee (on the left side of the left knee, for example), and the MCL is on the inside (on the right side of the left knee, for example). These ligaments prevent your knee from rotating too much in either direction.

Of all four of these ligaments, the ACL tears the most.

2. You don’t have to get tackled to injure your ACL

Generally speaking, there are two kinds of sports injuriescontact (where an external force, e.g. from a helmet, ball, or another body, is exerted on the ligament) and non-contact (where the injury results purely from excessive internal forces, such as from a sudden rotation or change of direction).

More than 70 percent of ACL injuries are non-contact, caused by sudden acceleration, deceleration, landing, and pivoting maneuvers. Tom Brady injured his after he took a helmet to the knee (a contact injury), but if your knee isn’t properly trained, you can get an ACL injury simply by landing, cutting, or pivoting the wrong way. That’s how it happens most of the time.

3. If you’re female, you’re more likely to experience an ACL injury

According to an editorial published in the Journal of Orthopaedics in 2016, women tear their ACLs “two to eight times” more often than men. Among basketball players, ACL injuries are 3.5 times more common among females than among males. Female soccer players are 2.8 times as vulnerable to ACL injury when compared to males.

Why is this the case? Evidence points to slight differences in the way male and female bodies work. For example, evidence shows that female athletes tend to be less effective at stiffening the knee and take slightly more time to produce maximum torque in the hamstring when compared to males.

In addition, some studies have found that female athletes tend to have more ACL injuries during ovulation as compared to the luteal phase of the menstrual cycle. This suggests the difference could be both hormonal and structural, but the answer isn’t clear.


4. ACL injuries nearly always mean an early end to the season

Injuring your ACL is devastating and usually requires invasive surgery and a long period of rehab. Surgery involves removing the damaged ACL and replacing it with part of another ligament, and recovery can take one to two years or longer. If you think that’s bad, don’t worry — it gets worse.

About 350,000 ACL reconstructions take place every year, and 79 percent of those knees later develop osteoarthritis, which is irreversible. One in five individuals injure the ACL again within two years of surgery. The worst part, though, is that the rates of ACL injury are increasing every year.

5. ACL injuries can be prevented with proper training and conditioning

Non-contact ACL injuries occur when a movement pattern places excessive force on the ACL. 

To make sure the ACL never ends up in this vulnerable position, you have to make sure your core and leg muscles — which are far stronger than your ACL — are capable of doing most of that stabilizing work.

This means two things: (1) perfecting your form and (2) using functional exercises at the speed of sport to improve the conversation between your muscles and your brain.

the TB12 ACL Injury Prevention Program

“With the overwhelming number of ACL injuries that are sustained throughout athletics each year, it is imperative that we as athletes, coaches, parents, and health care providers do everything in our power to remain proactive in the prevention of ACL injuries.”

— tom brady, TB12 Co-founder

We designed the TB12 ACL Injury Prevention Program to provide coaches, parents, and athletes with the information and motivational tools necessary for reducing the risk of season-ending (and potentially career-altering) knee injuries.

The course focuses on enhancing awareness regarding the mechanism of ACL injury and specific ACL injury risk factors, empowering athletes to create daily change and improvement in their physical capabilities, and improving athletes’ ownership over their prevention programming.

Get the program


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