What is the ACL?
The anterior cruciate ligament (ACL) is one of the major ligaments of the knee. It is located in the middle of the knee and runs from the femur (thighbone) to the tibia (shinbone). The ACL prevents the tibia from sliding out in front of the femur. Together with the posterior cruciate ligament (PCL) and posterolateral corner (PLC), it provides rotational stability to the knee.
Causes of ACL Tears
An ACL injury is a sports-related injury that occurs when the knee is forcefully twisted or hyperextended. An ACL tear usually occurs with an abrupt directional change when the foot is fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can also cause injury to the ACL. Most ACL injuries are from non-contact mechanisms.
Symptoms of ACL Tears
When you injure your ACL, you may hear a pop sound and may feel as though the knee has given way. Within the first two hours after injury, your knee will swell and you may have a buckling sensation in the knee during twisting movements.
Diagnosis of ACL Tears
The diagnosis of an ACL tear is made by reviewing your symptoms and medical history and performing a physical examination of the knee. Other diagnostic tests such as X-rays, MRI scans, stress tests of the ligament and arthroscopy may also be ordered.
Treatment of ACL Tears
Treatment options include both non-surgical and surgical methods depending on the extent of the tear and activity level of the patient. If the overall stability of the knee is intact, your doctor may recommend non-surgical methods. Non-surgical treatment consists of initial rest, ice, compression and elevation (RICE protocol); all of these assists in controlling pain and swelling. Physical therapy may be recommended to improve knee motion and strength. A knee brace may be needed to help stabilize the knee.
Active patients and athletes involved in pivoting sports will most likely require surgery to safely return to sports. The usual surgery for an ACL tear is an ACL reconstruction which tightens your knee and restores its stability. Surgery to reconstruct an ACL is performed with an arthroscope, using small incisions. During the surgery, your doctor will replace the torn ligament with a tissue graft that can be obtained from your knee (autograft) or from a donor (allograft).
Following ACL reconstruction, a rehabilitation program is started to help you resume a wider range of activities.