ACL injury

Diagnosis

Diagnosis of ACL injury begins with a physical exam and detailed history. During the exam, your healthcare professional may check your knee for swelling and tenderness and compares it with your other knee. Your healthcare professional also may move your knee into a variety of positions. This is done to check your range of motion and see how well the knee moves and works.

Often the physical exam is enough to diagnosis an ACL injury. But you may need more tests to rule out other issues and to see how serious the injury is. These tests may include:

• X-rays. X-rays may be needed to rule out a bone fracture. However, X-rays do not show soft tissues, such as ligaments and tendons.
• Magnetic resonance imaging (MRI). An MRI uses radio waves and a strong magnetic field to create images of both hard and soft tissues in your body. An MRI can show the extent of an ACL injury and any damage to other tissues in the knee, including other ligaments, cartilage and the meniscus.
• Ultrasound. This test uses sound waves to visualize internal structures. Ultrasound may be used to check for injuries in the ligaments, tendons and muscles of the knee.

Treatment

Treatment for ACL injury depends on how serious the injury is, your activity level and the stability of your knee. Some injuries can be treated without surgery. Others need surgery to reconstruct the ligament.

Nonsurgical care

For partial tears or for people who are less active, treatment may include the R.I.C.E. method to lessen pain and swelling:

• Rest. Take it easy and avoid putting weight on your knee as you heal.
• Ice. Put ice on your knee for 20 minutes every two hours while you are awake.
• Compression. Wrap your knee with an elastic bandage or compression wrap.
• Elevation. Lie down and prop your knee up on pillows.

Treatment without surgery also may include:

• Bracing. Wearing a brace to keep your knee stable.
• Crutches. Using crutches to avoid putting weight on your knee while it heals.
• Physical therapy. Doing exercises to restore motion and strengthen supporting muscles.
• Activity modification. Avoiding movements that involve cutting or pivoting.

The goal of rehabilitation is to lessen pain and swelling, restore your knee's full range of motion, and strengthen your muscles. This approach can work well to treat an ACL injury for people who do not have instability in the knee. Nonsurgical treatment also can work well for people who are not very active, do moderate exercise, or play sports or do activities that put less stress on the knees.

Surgical reconstruction

If you have a complete ACL tear or are very active, you may need surgery. Your healthcare professional may recommend surgery if:

• You are an athlete and want to keep playing sports, especially those that involve jumping, cutting or pivoting.
• More than one ligament or the meniscus or cartilage in your knee also is injured.
• The injury is causing your knee to give out during everyday activities.

Before surgery, you likely will do some physical therapy to strengthen your knee and improve your range of motion.

During ACL reconstruction, the surgeon removes the damaged ligament and replaces it with a piece of tendon. This is tissue similar to a ligament that connects muscle to bone. This replacement tissue is called a graft. Your surgeon uses a piece of tendon from another part of your knee or a tendon from a deceased donor.

Physical therapy

Physical therapy after surgery is important. Successful ACL reconstruction combined with rigorous rehabilitation can usually restore stability and function to your knee. A physical therapist teaches you exercises that you can do either with the therapist's help or at home. You also may wear a brace to stabilize your knee and use crutches for a while to avoid putting weight on your knee. Rehabilitation focuses on:

• Early range of motion and pain control.
• Gradual strengthening of leg and core muscles.
• Balance and neuromuscular training to restore knee control.

There is no set time frame for athletes to return to play. Research shows that up to one-third of athletes may have another knee injury in the same or opposite knee within two years, especially with high-risk sports such as soccer. A longer recovery period may reduce the risk of reinjury.

In general, it can take a year or more before athletes can safely return to play. Your healthcare team and physical therapists test your knee's stability, strength, function and readiness to return to sports activities at various points during your rehabilitation. It is important to ensure that strength, stability and movement patterns are well-developed before you return to an activity with a risk of ACL injury.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Preparing for your appointment

Because ACL injury causes a lot of pain and makes the knee hard to move, many people seek medical attention right away. Others may make an appointment with their family healthcare professional. Depending on how serious your injury is, you may be referred to a healthcare professional specializing in sports medicine or an orthopedic surgeon, who specializes in bone and joint surgery.

What you can do

Before an appointment, be prepared to answer the following questions:

• When did the injury happen?
• What were you doing at the time?
• Did you hear a loud pop or feel a popping sensation?
• Was there much swelling afterward?
• Have you injured your knee before?
• Have your symptoms been constant or do they come and go?
• Do any specific movements seem to improve or worsen your symptoms?
• Does your knee ever lock or feel blocked when you are trying to move it?
• Do you ever feel that your knee is not stable or not able to support your weight?