As the 2026 World Cup kicks off, one of soccer’s most dreaded injuries is already sidelining stars and reigniting questions about why anterior cruciate ligament, or ACL, tears are so common in the sport.
Chris Kuenze is an athletic trainer and associate professor in UVA’s School of Education and Human Development. One of his specialties is studying ways to support people recovering physically and mentally from ACL injuries. (Photo by Matt Riley, University Communications)
During the 2023 Women’s World Cup, the large number of ACL tears that elite female soccer players experienced made news, and for good reason: Research shows that in elite soccer, women are 2½ to 3 times more likely than men to experience an ACL injury at the same level of competition.
But male athletes are not immune. Of the players missing this summer’s men’s World Cup, many are suffering ACL tears.
To better understand this injury, we turned to Chris Kuenze, an athletic trainer and associate professor in the University of Virginia’s School of Education and Human Development. Kuenze studies ways to support people as they recover both physically and mentally from ACL injuries.
Q. What happens when an ACL is torn?
A. An ACL is like a bungee cord inside the knee that keeps the two bones (femur and tibia) connected. It also helps the knee stay stable when it flexes and extends, or when a person does things like pivoting, landing or rapidly decelerating.
When reports indicate that an athlete has a torn ACL, it can mean that the bungee cord has completely torn in half, or that part of it is torn while a smaller part of it is intact.
Q. Why does that injury limit function so significantly?
A. Not to kill the metaphor, but a broken bungee cord isn’t very good at keeping your trunk closed when you bring home too much stuff from Lowe’s or HomeGoods.
When an athlete has an ACL tear, they lose one of a small number of bungee cords that keep their knee functioning the way it is meant to. When this happens, the knee becomes less stable, and your brain starts to get feedback from your joint and muscles that indicates that something isn’t right.
Your body goes into protection mode and tries to make it harder for you to do challenging tasks while making sure that your knee is as stable as it can be under the circumstances.
An ACL injury also hurts a good amount, and the knee tends to swell a lot, which can make people hesitant to do even basic activities like walking or climbing stairs.
Q. What about soccer makes ACL tears more likely?
A. Between 60% to 70% of ACL injuries happen without any contact with another player. The ACL is put under stress when athletes change direction quickly, decelerate rapidly or land after jumping.
These noncontact stresses can be even higher when they are done in response to the behavior or movement of another player. Because of this, athletes who engage in sports like soccer (and lacrosse, basketball and football) have higher risks of ACL injury than those who participate in more predictable or straight-line sports like track or baseball.
However, ACL injuries can also happen from direct contact to the leg. Given that 30% of soccer injuries occur from direct contact with another player, actions like slide tackling also meaningfully contribute to the risk of injury.
Q. Many athletes return to competition after these injuries, some more quickly than an average person. How do they do that?
A. Elite athletes are just that, elite. Their anatomy, physiology and mental health/psychology tend to be different than the typical person, especially at the level of a professional soccer player going to the World Cup.
