What is the ACL?

There are four major ligaments in the knee. The ligaments attach three bones: the thighbone (femur), the shinbone (tibia) and the knee cap (patella). There are 2 groups of ligaments in the knee; the collateral ligaments and the cruciate ligaments. The anterior cruciate ligament or ACL is one of the cruciate ligaments.

The two collateral ligaments are known as the medial collateral ligament and the lateral collateral ligament. The medial collateral ligaments are on the side of the knee and control sideways motion of the knee. These bands of tissue are intended to protect the knee from extending too far to either side.

The two crutiate ligaments are known as the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). These two bands cross each other to form an “X”. The ACL is in the front and runs diagonally across the middle of the knee. The ACL and PCL keep the knee from moving too far forward or backward.

The ACL is the most commonly injured of all the ligaments in the knee. The ACL is key to providing stability in the knee and minimizing stress within the knee joint. When injured, surgery is typically required to recover from the injury. 

In future articles, we will discuss ACL injuries and injury prevention in greater detail. If you feel you may have injured your ACL it is extremely important to consult an orthopedic surgeon.