Anterior Cruciate Ligament (ACL) Tear of the Knee

What is an ACL tear of the knee?

ACL tears are one of the most common knee ligament injuries. The ACL runs diagonally in the middle of the knee. It connects the back of the femur (thighbone) to the front of the tibia (shinbone) and helps stabilize the knee from rotating. Injuries range from mild, small tears, to severe tears when the ligament and part of the bone separate from the rest of the bone. Most ACL injuries are complete or near-complete tears.


How does an ACL tear occur?

turning and jumping are especially susceptible. They may feel a slip or pop in their knee and the knee gives out from under them. ACL tears are extremely common in young women athletes, and often occur together with injuries to the meniscus.

There’s not a lot you can do to prevent ACL tears. They happen to everyone – even pro athletes in great shape, such as Redskins quarterback Robert Griffin, III.


What are the symptoms of an ACL tear?

People who suffer an ACL tear usually hear a loud pop at the time of their injury or feel a sudden shift in their knee joint. Pain ranges from mild to excruciating, depending on the severity of the injury.

Other symptoms include:

  • Knee swelling and stiffness
  • Instability in the knee joint
  • Limited range of motion
  • Discomfort while walking
  • Tenderness along the joint line

Sometimes the initial pain and swelling resolve on their own. If you attempt to return to sports without any treatment, however, you risk causing further damage to your knee.

How is an ACL tear diagnosed?

In addition to a physical exam and patient history, MRI is the most effective test to confirm the diagnosis of a torn ACL or associated knee injuries.

What is the treatment?

ACL tears do not necessarily require surgery. Initial treatment focuses on pain control, restoring range of motion and preventing further injury. It is important to regain motion in the knee as soon as possible to aid in recovery.

The decision for operative or non-operative treatment depends on several factors including a patient’s age, activity level, severity of symptoms and expectations. For older, sedentary patients with a relatively stable knee and little desire to return to high-level sports or fitness routines, non-operative rehabilitation and activity modification may be sufficient. For active patients of almost all ages –   especially young athletes – reconstruction of an ACL tear is highly recommended. Stable knees are critical for safely returning to sports and preventing re-injury or additional injury. ACL reconstruction can also minimize the chance of knee arthritis or instability later in life.

ACL reconstructive surgery uses an autograft (tissue from your body) or an allograft (tissue from a cadaver) to replace the ligament. The graft selected for reconstruction is individualized based on a patient’s age, the surgeon’s preference, and the expected physical demands in the future. This should be discussed specifically with your surgeon.

Return to daily and sports activities varies depending on the surgery and your surgeon. Usually, return to sporting activity is restricted for at least six months. An appropriate physical therapy program is considered critical for the success of ACL reconstruction.


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