The ACL (Anterior Cruciate Ligament) is one of the ligaments of the knee that keeps the knee stable and flexible. The ACL runs diagonally in the middle of the knee and forms an X with the Posterior Cruciate Ligament. These ligaments provide the back and forth motion and rotation of the knee. These ligaments also prevent the tibia from sliding in front of the femur.
An ACL injury occurs when this ligament becomes torn due to overexertion or hyperextension. This is one of the more common injuries in soccer, football, basketball, baseball and other sports.
ACL injuries often occur in athletes as a result of a hyperextension or sudden impact such as:
- A quick change in direction
- A sudden stop while running
- Impact to the ligament such as from a foot or helmet
- Jumping or landing improperly
Injuries can range from:
Grade 1: The ACL has been stretched or mildly damaged but is still able to provide support to the knee.
Grade 2: The ACL has been stretched to the point where it becomes loose and unable to provide support to the knee. This is also commonly referred to as a “partial ACL tear”.
Grade 3: The ACL has been has been completely torn and is no longer one complete ligament. The ligament has become detached from the bone and is no longer able to provide any support to the knee. This is also commonly referred to as a “complete ACL tear”.
If you suspect that an ACL injury has occurred it is important to seek medical attention as soon as possible. Continued activity on the injured ligament may exacerbate the injury and increase the grade of injury.
Signs and symptoms of an ACL injury can vary but may include:
- Hearing a “popping” sound at the moment of injury
- Swelling within 24 hours
- Pain on the outside or the back of the knee
- Limited range of motion
- Inability to bear weight on the injured knee
- Feeling of the knee “buckling” or “giving out” while walking
- Tenderness on the outside or back of the knee