Anterior Cruciate Ligament (ACL) Tears

The ACL is a main stabilizer of the knee that connects the tibia (shin bone) to the femur (thigh bone).

The Anterior Cruciate Ligament (ACL) acts as a piece of rope that holds the knee together.  It runs through the middle of the knee, keeping the tibia (shin bone) from moving forward on the femur (thigh bone). It also helps to prevent rotation between the two bones.  The ACL is essential for normal knee function in aggressive running, cutting, and jumping-type activities.  


Often, other structures in the knee can also be injured in addition the tearing of the ACL.

  • Bone bruises are present in 60-80% of ACL tears. They can cause a significant amount of pain on their own. This is worse with weight-bearing and may be a reason to use crutches.
  • Meniscal tears are often associated with ACL injuries.  These can occur at the same time as the ACL injury or from a separate instability episode after the ACL was torn.
  • The articular cartilage can also be damaged at the time of an ACL injury or from another instability episode.
  • Occasionally, one of the other ligaments of the knee is injured with the ACL. This makes the knee even less stable. It also can affect the timing of any surgery, how much surgery we recommend, and the rehabilitation after surgery.