An anterior cruciate ligament (ACL) tear is an injury to the ligament in your knee that keeps your shinbone from sliding forward. The ACL stabilizes your knee, and tearing it either partially or completely can cause pain and swelling.
ACL injuries are commonly seen in basketball, football, and soccer players, who often jump or pivot in reaction to other athletes. Ignoring a torn ACL can potentially lead to further knee injury.
ACL tears are typically seen in highly active people. Here are the movements that can lead to an ACL injury:
- landing flat-footed from a jump
- overextending your knee joint
- fast direction changes
- speed changes while running
You can also injure your ACL in an accident that causes the side of your knee to be hit (e.g., a car accident or a football tackle).
ACL tears are common sports injuries. Basketball, skiing, football, and soccer are a few sports that make athletes vulnerable to knee injuries. Compared with male athletes, ACL injuries are three to nine times more likely to occur in female athletes.
People who hurt their ACLs usually hear a popping sound as soon as they injure themselves. Swelling usually occurs in the knee within six hours of injury. The condition can be painful, especially when walking, twisting, or turning on your injured leg. You will generally also feel that your knee is unstable, giving out from underneath you.
An ACL tear needs to be examined by an orthopedic surgeon or a knee specialist. The doctor will review your medical history and ask how you injured yourself. The physical exam typically includes observing your knee’s stability and range of movement. Your doctor may also order the following tests:
- An X-ray will help determine whether there are any broken bones.
- An MRI helps to specifically diagnose an ACL tear and examine the other ligaments in your knee.
- If there are concerns about small bone fractures, you might need a computed tomography (CT) scan of your knee.
Treatment for an ACL tear depends on the extent of your injury and your specific goals and needs. Some people can continue their normal lives with an ACL injury, but may later suffer from other knee injuries. For an athlete, surgery and physical therapy may be the best answers for resuming athletics as quickly as possible.
In all cases, it is important to see a health-care provider immediately to ensure there are no broken bones or damage to other ligaments. If your knee is blue, seek medical help immediately, as your blood vessels may be injured.
Here is what you should do until you can see a doctor:
- Refrain from physical activities until you have seen a doctor.
- Keep your leg still using a splint.
- Rest your leg and elevate it above the heart.
- Place ice on your knee to reduce the swelling.
- Use crutches to reduce pressure on your injured knee.
Sometimes this type of injury requires a complete surgical reconstruction using a tendon from the patella or hamstring. Using donor tissue is also an option. Following surgery, you may need up to six months of physical therapy to regain your full range of motion and leg strength.
When you first injure yourself, your doctor may recommend an over-the-counter pain reliever (e.g., ibuprofen). If you will undergo surgery, ask your doctor about the required medications for both before and after your surgery. Prior to surgery, you may be instructed to stop taking medicines that interfere with your blood’s ability to clot (e.g., aspirin).
Reconstructive surgeries usually have good outcomes, allowing you to have less pain and more leg strength and knee stability. With proper treatment, you should have a full recovery.
A strong and agile body reduces your risk for an ACL tear. If you are an athlete, learn and practice preventive techniques for reducing the pressure on your knees. Landing on the balls of your feet rather than flat-footed, for example, allows your calf muscles to support your body, decreasing unnecessary pressure on your knees.