What is it?
The anterior cruciate ligament (ACL) connects the upper leg bone with the lower leg bone and keeps the knee joint stable. An ACL injury occurs when one of these knee ligaments stretches or tears, which can range from a slight to complete tear.
Causes, Symptoms and Risk Factors
An ACL can be injured if your knee joint twists, or is unusually bent backward or to the side. This can occur during falls. Risk factors include:
- Past knee injuries
- Playing sports, such as football, basketball and soccer
- Participating in activities that require frequent and sudden changes in direction and stopping
Symptoms of an ACL injury include:
- A noticeable pop in the knee at the time of injury
- Pain on the outside and back of the knee
- Limited movement
- A feeling of joint instability
A doctor will diagnose an ACL injury by examining the joint and its stability and range of motion; reviewing symptoms and medical history; conducting X-rays or an MRI to look for damage to the bone, cartilage, ligaments, tendons or muscles; or an arthroscopic procedure to look inside the joint.
Treatment for an ACL injury includes:
If these treatments do not allow the joint to heal properly or if the injury is significant, the doctor may recommend surgery to repair the damage and stabilize the knee joint.
- Resting the joint
- Icing the joint
- Compressing the knee by wrapping it with an elastic bandage
- Elevating the leg above heart level
- Reducing motion and stress on the joint by, for example, using crutches or a knee immobilizer
- Taking pain medication
- Physical therapy