Anterior cruciate ligament injury (patient information)

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Overview
The anterior cruciate ligament (ACL) is a ligament in the center of the knee that prevents the shin bone (tibia) from moving forward on the thigh bone (femur). An anterior cruciate ligament (ACL) injury is the over-stretching or tearing of the anterior cruciate ligament in the knee. A tear may be partial or complete.

What are the symptoms of Anterior cruciate ligament injury?
Common early symptoms:
 * A "popping" sound at the time of injury
 * Knee swelling within six hours of injury
 * Pain, especially when you try to put weight on the injured leg

Those who have only a mild injury may notice that the knee feels unstable or seems to "give way" when using it.

What causes Anterior cruciate ligament injury?
ACL tears may be due to contact or noncontact injuries. A blow to the side of the knee, which can occur during a football tackle, may result in an ACL tear.

Coming to a quick stop, combined with a direction change while running, pivoting, landing from a jump, or overextending the knee joint (called hyperextended knee), also can cause injury to the ACL.

Basketball, football, soccer, and skiing are common causes of ACL tears.

Who is at highest risk?
Women are more likely to have an ACL tear than men. The cause for this is not completely understood, but it may be due to differences in anatomy and muscle function.

Athletes, especially those who ski, or play basketball, football, or soccer, are at risk for injuring their ACLs.

When to seek urgent medical care?
In the case of a serious knee injury, do NOT try to move the joint. Use a splint to keep the knee straight until a trained medical professional has evaluated it.

Anyone with a serious knee injury should seek medical attention for x-rays and evaluation.

If the foot is cool and blue after a knee injury, the knee may be dislocated, and blood vessels to the foot may be injured. This is a true medical emergency that requires immediate professional help.

Diagnosis
When your doctor suspects an ACL tear, an MRI may help confirm the diagnosis. This test may also help evaluate other knee injuries, such as to the other ligaments or cartilage.

The Lachman test may also be performed by your doctor at your physical examination.

Treatment options
An ACL injury should be treated with:
 * Elevating the joint above the level of the heart
 * Ice
 * Pain relievers such as nonsteroidal anti-inflammatory drugs (NSAIDs) (like ibuprofen)

Some people may need crutches to walk until the swelling and pain have improved. For mild injuries, your doctor may suggest physical therapy to help you regain joint motion and leg strength.

Your doctor may also recommend reconstructive surgery. The old ligament cannot be fixed, so a new one needs to be constructed.

Do NOT participate in rigorous physical activity until you have been evaluated and treated.

Where to find medical care for Anterior cruciate ligament injury?
Directions to Hospitals Treating Anterior cruciate ligament injury

What to expect (Outlook/Prognosis)?
Some people are able to live and function normally with a torn ACL. However, most people complain that their knee is unstable and may "give out" with physical activity. ACL tears that are not repaired may also lead to tissue damage and early arthritis in the affected knee.

ACL reconstruction is usually very successful. A torn ACL used to end the careers of many athletes. Now, improvements in the surgery and in rehabilitation provide much better results. These improvements include less pain and stiffness, fewer complications with the surgery itself, and faster recovery time. Most people will have a stable knee that does not give way after ACL reconstruction.

Possible complications
Risks of ACL reconstruction surgery are similar to those of any surgery, such as
 * Allergic reaction to medication
 * Breathing problems
 * Bleeding
 * Infection

Additional possible complications of ACL reconstruction surgery include:
 * Stiffness of the knee or lost range of motion
 * Failure of the surgery to relieve symptoms
 * Failure of the ligament to heal
 * Pain or weakness in the knee
 * Blood clot in the leg
 * Injury to a nearby blood vessel

Possible complications of ACL injuries that are not repaired include tissue damage and early arthritis in the joint.

Prevention
Use proper techniques when playing sports or exercising. Several women's college sports programs have reduced ACL tears through a training program that teaches athletes how to minimize the stress they place on their ACL.