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Knee Ligament Injuries: Tears of the Anterior Cruciate Ligament (ACL)

Overview of ACL Tears

The ACL, or anterior cruciate ligament, is a commonly torn ligament in the knee that helps provide stability.  Active patients can be at risk for ACL tears.  ACL tears are relatively common, with between 70,000 to 80,000 cases reported each year in the United States alone.  Often these injuries do not result from collision with another player, but can occur when a person suddenly changes directions, pivots, or lands incorrectly after a jump.

Signs of an ACL tear

ACL tears should be suspected after a knee injury in a patient of any age.  There is usually pain, swelling and feelings of instability when the ACL is torn.  Sometimes, placing weight through the leg is difficult.  Often, a “pop” can be heard at the moment the tearing occurs.

How is an ACL tear diagnosed?

If you suspect you may have torn your ACL, you are advised to stay off the leg and keep it elevated to prevent swelling.  If you have a pair of crutches, these may be helpful until your knee is evaluated by a Summit physician.  Applying ice to the knee can reduce pain and inflammation.

The physician will perform a physical exam to test the strength of the ACL.  In addition, other ligaments such as the PCL and MCL are tested to ensure there are no other injuries present.  Xrays of the knee are ordered to look for fractures.  Sometimes, an MRI is also ordered to confirm that the ACL is torn and to look for damage to the meniscus cartilage in the knee.

What are my treatment options?

Initially, many people with a torn ACL are treated with physical therapy to help regain motion, reduce swelling, and strengthen the leg.  Whether to proceed with surgical reconstruction of the ACL depends on many factors, including the patient’s lifestyle.  Individuals who enjoy remaining active may have persistent instability or sensation of the knee giving out if they opt for non-surgical treatment.  The meniscus cartilage is also at increased risk for tearing in patients without an ACL.

Because the ACL cannot be repaired, it is reconstructed surgically.  Tissue can be taken from the patient’s own hamstring tendons or central portion of the patellar tendon, or from a cadaver.  The procedures is performed with a small camera (arthroscope), although bigger incisions may be needed to harvest tissue.  Damage to the meniscus cartilage is also repaired during ACL reconstruction.

Recovery after ACL surgery

All patients are enrolled in a focused physical therapy program after surgery.  This helps restore motion and strength to the knee, especially to the quadriceps.  It is very important to prevent stiffness.  Recovery time varies between patients and depends on the type of graft used, but usually takes between 6 to 9 months.