The anterior cruciate ligament (ACL) is one of four main knee ligaments and acts to stabilize the knee. The ACL runs diagonally in the middle of the knee and connects the thighbone (femur) to the shinbone (tibia). It is one of the most commonly injured knee ligaments.
What causes an ACL injury?
ACL injuries most commonly occur as a noncontact injury in sports when a child or teen is making a cutting and pivoting movement, or when they are jumping and landing. They can also occur as a result of a contact injury, such as during a tackle in soccer or collision in football.
Who is at risk for an ACL injury?
The group of athletes with the highest risk to get an ACL injury are teenagers. Girls ages 13 to 15 and boys ages 14 to 16 are at high risk for ACL injuries due to rapid growth, an athlete’s muscles having to “catch up” with their growth in height, increased time playing a sport and longer sports seasons.
Kids who play the following sports are more likely to have an ACL injury: soccer, basketball, football, lacrosse, gymnastics and competitive cheer.
Are girls more likely to tear an ACL than boys?
Girls are four to eight times more likely to suffer an ACL injury than boys. There are many factors thought to contribute to this increased risk, many of which are related to differences in anatomy, as well as jumping and landing mechanics. Some of these differences include:
- Hips: Girls have wider hips than boys, which increases the angle on the knee joint. This can put increased force on the ACL, especially with jumping and landing, and while making cutting movements. The strength of the hip, core and thigh muscles are important to stabilize the knee while a child is jumping and landing. These muscles are frequently weak or imbalanced in teenage athletes.
- Knees: The ACL passes through the middle of the knee in an area called the intercondylar notch. Girls have a narrower notch on the inside of their knee, which leaves their ACL more subject to getting injured during sudden stops or direction changes.
- Quadriceps: Hamstrings (muscles in the back of the thigh) protect the ACL. Quadriceps (muscles in the front of the thigh) put stress on the ACL. A girl’s quadriceps are typically stronger than her hamstrings, which make the ACL vulnerable to injury.