Anterior Cruciate Ligament (ACL) Tears


What is the anterior cruciate ligament?

There are four primary ligaments in your knee that hold the bones together and keep your knee stable.

Two of these ligaments are known as the cruciate ligaments. They cross each other to form an "X," with the anterior cruciate ligament (ACL) in front and the posterior cruciate ligament (PCL) in back. The cruciate ligaments control the back and forth motion of your knee. The anterior cruciate ligament (ACL) prevents the tibia (shin bone) from sliding out in front of the femur (thigh bone), and provides rotational stability to the knee.   

ACL injuries often happen during sports and activities that involve:

  • Suddenly changing direction (cutting)
  • Pivoting with your foot firmly planted
  • Landing awkwardly from a jump
  • Stopping suddenly
  • Receiving a direct blow to the knee or collision, such as a football tackle 


What are the symptoms of an ACL injury? 

Signs and symptoms of an ACL injury typically include:

  • A "popping" sensation in the knee
  • Pain and inability to continue activity
  • Swelling and stiffness
  • Loss of range of motion
  • A feeling of instability or "giving way" with weight bearing


How is an ACL tear diagnosed? 

During the physical examination, Dr. Potts will check your knee for swelling or any signs of injury — comparing your injured knee to your uninjured knee. He may also perform multiple tests to assess the stability, range of motion, and overall function of the joint. Often the diagnosis of an ACL tear can be made on the basis of the physical exam alone, but Dr. Potts may also order other imaging studies to confirm the diagnosis, assess the severity of the injury, and rule out further damage. These tests may include:

  • X-rays
    • X-rays may be needed to rule out a bone fracture. However, X-rays don't show soft tissues, such as ligaments and tendons.
  • Magnetic resonance imaging (MRI)
    • MRI imaging creates images of both hard and soft tissues in your body. An MRI can show the extent of an ACL injury and signs of damage to other tissues in the knee.

What is the treatment for an ACL tear?

ACL tears can range anywhere from a mild sprain to a complete rupture, so treatment depends on the severity of your condition. A torn ACL will not heal without surgery, but non-surgical treatment may be effective in older patients or those with a very low activity level. If your injury does not involve significant knee instability, Dr. Potts may recommend initial treatment with rest, ice, elevation and anti-inflammatory medications followed by physical therapy to restore function.

If your ACL is completely torn, your knee may have long-term problems with stability if left untreated. In most cases, Dr. Potts will recommend surgical reconstruction in younger patients and those who wish to return to full activity. ACL reconstruction surgery returns stability to the knee, protects the joint from future damage to the knee cartilage, and allows patients the ability to return to sports that require a fully functioning ACL.