Are you at risk for tearing your ACL?!


It’s one of the most feared injury in sports, an ACL tear. Such a common injury, at times it seems like an epidemic in high school, college and professional sports. While injuries are common in athletes, knee injuries account for 10-25% of all injuries, and an estimated 250,000 ACL injuries occur in the US each year. Of these ACL injuries, females are 6-8x more likely to tear their ACL’s compared to their male counterparts. And almost 80% of all ACL tears occur as a non-contact injury. A non-contact means an athlete tore their ACL without being hit by another player, and is most commonly seen in cutting, pivoting and landing from a jump. An ACL tear is a season-ending injury and requires surgery the majority of the time. Furthermore, once you’ve torn your ACL once, if you are an athlete under the age of 20, your chances of sustaining another tear goes up significantly. Even with an ACL surgery, return to sports and competition has been reported to be as low as 50%.

So the biggest question people are asking, is why? Why do most of these injuries happen without contact from another player, and why is it way more common in females vs. males? Sports medicine researchers have found over the years that the majority of these non-contact injuries happen because of “poor neuromuscular control,” resulting in the knee/leg in a bad position right as the leg hits the ground. These athletes demonstrate faulty movement patterns and improper muscle firing of the muscles around the trunk, hip and knee that puts the knee at a bad angle. The most common reason for these faulty movement patterns is excess dominance in the quadriceps/thigh muscles, with weakness and delayed muscle firing of the hamstring and gluteal muscles. When we observe an imbalance in these muscles, the knee will go into a “valgus” or knee inward position or a hyper-extension position of the leg, and the ACL will rupture. Since we have learned WHY these injuries occur, the more we have learned how to change or prevent them.

So, are you at risk for an ACL tear? There are several different ways you can tear your ACL, therefore there are multiple different ways to assess this. One of the first ways we look at this is watching an athlete perform a single leg squat. We look at the angle from her hip to her knee down to her ankle. If the knee falls inward (valgus position) past a certain angle, the athlete is at risk for a knee injury. The pictures below show a single leg squat performed on the right and left leg. You can see her left knee going inward significantly and her trunk is leaned way backward. However, on the right leg, she has good alignment of her trunk, knee and ankle without her knee going inward. She would be at a higher risk for injuring her left knee vs. right.









The other way to asses if you are at risk for tearing your ACL is observing an athlete jump down and up from a box. The pictures below show the landing phase of a jump down from a box. The markers on her hip, knee and ankle show the angle of her knee at the landing phase. You can clearly her knee goes into a valgus position right before she lands, at the deepest phase of landing and right as she takes off. If the angle is less than 60%, you are at a high risk for tearing your ACL. The angle of her knee at the landing phase was 38%, which indicates she is at high risk for an ACL injury.









Here at Rebound, these are a few of the key components we look at to determine if an athlete is at risk for tearing their ACL. There are many other factors that can contribute to an ACL tear such as hormonal fluctuations, the type of surface (grass vs. turf fields) and over-training. However, keep in mind, the biggest factor is poor neuromuscular control and this is a factor that can be changed. In part 2 of this blog post, we will discuss the effectiveness and types of ACL injury prevention programs out there. Stay tuned as we launch our summer session of Sportsmetrics, the first and largest ACL injury prevention program.

Becca Rauch



Are you at risk for tearing your ACL?

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