An ACL injury is a tear of the anterior cruciate ligament (KROO-she-ate), or ACL, inside the knee joint.
An ACL injury often occurs in sports that involve sudden stops and changes of direction, such as basketball, soccer, tennis, and volleyball. Immediately after an ACL injury, the knee may swell, feel unbalanced, and feel extremely painful to bear weight.
Many people hear or feel a pop-like sound in their knee when they have an ACL injury. Depending on the extent of your ACL injury, it can include surgery to replace the torn ligament, followed by rehabilitation exercises to help restore your strength and stability.
If your favorite sport involves spinning or jumping, a proper training program can reduce the risk of an ACL injury.
What are the symptoms of an ACL tear?
When an ACL occurs, signs and symptoms can include:
- Hearing a loud “pop”
- Severe pain and inability to continue activities
- Swelling of the knee usually occurs hours after the injury.
Most people seek immediate medical care after an ACL injury.
What is the cause of ACL Injury?
Ligaments are strong bands of tissue that connect one bone to another. The ACL, one of two ligaments that runs down the middle of the knee, connects the femur to the tibia and helps stabilize the knee joint. Most ACL injuries occur during sports and fitness activities.
Your ligament may tear when you stop or suddenly change direction, strike vertically with your foot (vertical pressure on the leg), rotate, or hyperextend the knee. Landing clumsily from a jump, such as falling while skiing downhill, can also injure your ACL.
Football tackles or motorcycle accidents can also cause an ACL injury. However, most ACL incidents occur without such contacts.
Complications of ACL injury
People who have experienced an ACL injury are at a higher risk of developing knee osteoarthritis, in which the cartilage of the joint breaks down and its smooth surface becomes rough. Even if you have surgery to reconstruct the ligament, you may get arthritis.
Preparing to see a doctor
The pain and disability associated with an ACL injury cause many people to seek immediate medical treatment. Some may refer to their family doctor. Depending on the severity of the injury, you may be referred to a sports medicine specialist or orthopedic surgeon.
Before visiting, you may need to write answers to the following questions:
- When did the damage occur?
- What did you do at that time?
- Did you hear a “pop” sound at first?
- Was there much inflation after that?
The orthopedist may ask some of the following questions:
- Are your symptoms constant or intermittent?
- Is there a particular movement that seems to make your pain better or worse?
- Have you ever felt your knee lock up or feel stuck when trying to move it?
- Have you ever felt that your knee is unstable or unable to support your weight?
Testing and diagnosis of ECL problems
During the physical exam, your doctor will check your knee for swelling or tenderness—comparing the affected knee with the healthy knee. He may also move your knee in different directions, which will help determine if the ACL has been torn.
Diagnosis can often be made using a physical exam alone, but you may need tests to rule out other injuries and to determine the extent of the injury. These tests can include the following:
- X-rays: X-rays may be needed to rule out broken bones. However, X-rays cannot image soft tissues such as ligaments and tendons.
- Magnetic resonance imaging (MRI): MRI uses radio waves and a strong magnetic field to create images of both soft and hard tissues in your body. An MRI can determine the extent of ACL damage and show the presence of injuries to other knee ligaments or joint cartilage.
- Ultrasound: Ultrasound can be used to check for damage to the ligaments, tendons, and muscles of the knee.
Risk factors related to ACL
In similar sports, women are at significantly higher risk for ACL tears.
Women usually have an imbalance in strength, with the muscles in the front of the thigh (quadriceps) being stronger than the muscles in the back of the thigh (hamstrings).
The hamstrings prevent the shin bone from moving forward too much during activities.
When landing from a jump, some women may land in a position that increases the stress on their ACL.
ECL treatment methods and drugs
Initial treatment for an ACL injury is aimed at reducing pain and swelling in your knee, restoring normal joint motion, and strengthening the muscles around the knee.
You and your doctor then decide if you need surgery plus rehabilitation or rehabilitation alone.
The choice depends on several factors, including the extent of the knee injury, and your desire to improve your activities.
Athletes looking to return to sports that involve sudden stops, turns, or jumps usually seek surgical reconstruction to prevent imbalance events. Most inactive people with low cartilage or other ligament injuries can usually recover their knee stability with rehabilitation alone.
Whether you have surgery on your knee or not, you need rehabilitation. Treatment includes the following:
- Use of crutches, and possibly knee braces.
- Range of motion exercises to regain full knee motion
- Muscle and balance exercises
A torn ACL cannot retract properly, so the ligament is usually replaced with a piece of tendon from another part of the knee or leg. A tendon graft from a deceased donor can also be a solution.
This surgery is usually done through small incisions around your knee joint. A narrow light beam is used to visualize the site and to guide the location of the torn ACL joint.
If you choose non-surgical treatment for an ACL injury, you should avoid sports that involve sudden stops, twisting, or jumping. Self-care treatments you can do at home:
- Rest: Using crutches to avoid putting too much weight on the knee after an injury
- Ice: While you are awake, try to ice your knee for at least 20 minutes every two hours.
- Compressing: placing an elastic bandage or compression bandage around the knee
- Elevation: Lying down with your knees on a pillow.
ACL injury prevention
To reduce the chance of an ACL injury, use these guidelines:
- Improve your conditioning: Do exercise programs that have been shown to help reduce ACL injury, especially those that include strength and balance exercises, aerobics, plyometrics, jumping exercises, and awareness exercises. They are dangerous. Exercises that improve balance can also be beneficial when combined with other exercises.
- Strengthening the hamstrings: Female athletes in particular should make sure that they have strengthened their hamstrings as well as their quadriceps.
- Use proper technique: If your sport involves movements such as jumping, learn how to land properly. Studies have shown that if your knee bends inward after landing from a jump, you are more likely to injure your ACL. Technique training along with strengthening some thigh muscles can help reduce the risk.
- Check your gear: On the ski slopes, make sure your ski bindings are properly fastened by a trained professional.