What is the ACL?

The anterior cruciate ligament, most often referred to as the ACL, is one of four major ligaments that stabilizes the knee joint. A ligament is a tough band of fibrous tissue, similar to a rope, which connects the bones together at a joint.

The ACL prevents the lower bone (tibia) from sliding forward too much and stabilizes the knee to allow cutting, twisting and jumping sports.

How can the ACL tear?

The most common mechanism that tears the ACL is the combination of a sudden stopping motion on the leg while quickly twisting on the knee. ACLs can also tear from contact injuries, which force the knee into an abnormal position.

What are the signs that an ACL is torn?

When the ACL tears, the person feels the knee go out of joint and often hears or feels a “pop.” If he or she tries to stand on the leg, the knee may feel unstable and give out. The knee usually swells a great deal immediately (within two hours). Over the next several hours, pain often increases and it becomes difficult to walk.

If a tear is suspected, immediately apply ice and gentle compression until the injury can be evaluated by a professional. The knee should be evaluated by a doctor to see which ligaments are torn and to be sure other structures such as tendons, arteries, nerves, etc. have not been injured. X-rays are taken to rule out a fracture. Sometimes an MRI is needed, but usually the diagnosis can be made by physical examination.

If no structure other than the ACL is injured, the knee usually regains its range of motion and is painless after 6-8 weeks. The knee may feel normal; however, it can be a “trick knee,” meaning it can give way or be unstable, leading way to further and more serious injury if left untreated.

Some ACL injuries may not require surgery; most often when the patient is over forty years old and relatively inactive in sports. Those younger than thirty years old, regardless of activity level, are recommended to have surgery. Your provider at the Bone and Joint Center will work with you to determine the best options for ACL injury recovery depending on your lifestyle.

Treatment Options for a Torn ACL

    Some patients can function reasonably well even if the ACL is torn, especially with rehabilitation that restores the supporting muscle strength, power, coordination, and endurance to help stabilize the knee. The key to prevent the knee that has a torn ACL from giving out is to avoid quick pivoting motions. Wearing a knee brace can help by acting as a constant reminder to proceed with care – however, it will not completely stabilize a knee with a torn ACL. If no operation takes place, a quick change in direction can easily cause the knee to give way, so it is recommended that if a patient has an extremely active lifestyle, they consider surgery to fully protect their knee.
    Many knees in which the ACL is torn have additional injuries such as torn menisci or fragments of articular cartilage that are knocked loose (creating a loose body and a defect in the articular cartilage). These associated injuries can cause symptoms of pain, swelling, and locking (in addition to symptoms of giving way due to a torn ACL). Arthroscopic surgery to remove torn menisci or to remove loose bodies can improve pain and eliminate locking. However, it would usually not eliminate symptoms of instability.
    Surgical reconstruction of a torn ACL involves replacing the torn ACL with tissue (called a “graft”) from another part of the knee and putting it into a position to take the place of the torn ACL. The operation is commonly performed arthroscopically, which means it is minimally invasive instead of ‘open’ involving large incisions. Postoperatively, an accelerated rehabilitation program allows the patient to fully bear weight as soon as two weeks after surgery.

The experts at the St. Elizabeth’s Medical Center Bone and Joint Center are experienced in diagnosing, treating and repairing ACL injuries. Our orthopedic physicians work closely with a multidisciplinary team to ensure a smooth and speedy recovery, from the time of diagnosis through your recovery period.