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  • Writer's pictureJay Kasthuriarachchi

Risk Factors in an ACL injury

Updated: Oct 16, 2023

An ACL injury can be one of the most catastrophic injuries that can occur in sports. It often requires a long lay off, months of rehab, and expensive surgery.

Victor Radley and Sam Verrils, playing for the Roosters both ruptured their ACL within 15 minutes of each other in the 2020 season playing in the NRL.

Before we can talk about how to prevent an ACL injury, we need to find out HOW it happens.

Lets look at the risk factors first. These are some non- modififable factors that can cause an ACL injury

Q Angle and ACL Injury
Q Angle

Female- Females are more likely to rupture their ACL (some studies show they are 3 x more likely). This has been seen on the AFLW, with a huge amount of female athletes rupturing their ACL. There are a number of reasons for that, including the difference in muscle control and strength, and the larger Q- angle (angle lining up the femur and the knee)

Sports involving pivoting or sudden deceleration- we will go through the exact mechanism later on, but sports like soccer, rugby, skiing, or volleyball that require change of direction or sudden deceleration are a risk factor for ACL injury

Previously torn ACL- it sounds silly, but a major risk factor for an ACL a previous ACL injury

So how does an ACL injury occur?

There are two main ways an ACL injury can occur- either jumping and landing poorly, or during the act of change of direction


There are a number of factors that occur for an ACL to rupture.

Side Stepping ACL rupture

Deceleration- Change of direction requires effective deceleration, before accelerating in a different direction. Not being able to decelerate effectively is a major risk factor for ACL rupture

Hip position- The hip will normally be abducted (move away from the body). This is a key component of an ACL injury, often your leg will be outside your centre of mass. The above picture illustrates this well. The foot and knee are well away from where the hip is, while the player is change direction.

Knee position- This is an

Knee Valgus ACL Injury

easy one, and the most commonly described. "knee valgus" is the term used to describe the position of the knee. This is when the knee 'buckles in'. The below picture illustrates this position. Furthermore, during an ACL rupture, there will often be a twisting motion at the knee joint, further stressing the ACL.

These are not all the risk factors, but the main ones.

At SportsFit, we pride ourselves on being the leaders in rehab and return to sport on ACL injuries. Contact us to learn more

Want to learn more about ACL injuries? Check out our new ACL specific website here


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