Medicine and Health
An anterior cruciate ligament injury is the over-stretching or tearing of the anterior cruciate ligament (ACL) in the knee. A tear may be partial or complete.
Knee arthroscopy is surgery that is done to checkfor problems, usinga tiny camera to see inside your knee. Other medical instruments may also be inserted to repair your knee.
Considerations
The knee jointis located where the end of the thigh bone (femur) meetsthe top of the shin bone(tibia).
Four main ligaments connectthese two bones:
- Medial collateral ligament(MCL) runs alongthe inside of the knee.It prevents the knee from bending inward.
- Lateral collateral ligament (LCL) runs along the outside of the knee. It prevents the knee from bending outward.
- Anterior cruciateligament (ACL) is in the middle of the knee.It prevents the shin bone from slidingout in front of the thigh bone.
- Posterior cruciateligament (PCL) works with the ACL. It prevents the shin bone from slidingbackward under the femur.
Women are more likelyto have an ACL tear than men.
Causes
An ACL injury can occur if you:
- Get hit very hard on the side of your knee,such as duringa football tackleOverextending your knee joint
- Quickly stop moving and change direction while running, landingfrom a jump, or turning
Basketball, football,soccer, and skiingare common sportslinked to ACL tears.
ACLinjuriesoftenoccurwithotherinjuries.Forexample,anACLtearoftenoccursalong with tears to the MCL and the shock-absorbing cartilage in the knee(meniscus).
Most ACL tears occur in the middle of the ligament, or the ligamentis pulled off the thigh bone. These injuries form a gap between the torn edges,and do not heal on theirown.
Symptoms
Early symptoms:
- A "popping" sound at the time of injury
- Obvious knee swelling (/health-library/symptoms/joint-swelling) within 6 hours of injury
- Pain, especially when you try to put weight on the injuredleg Difficulty in continuing with your sport
- Feeling of instability
Those who have only a mild injury may noticethat the knee feels unstableor seems to "give way" when using it.
First Aid
See your health care provider if you think you have an ACL injury. Do not play sports or other activities until you have seen a provider and have been treated.
Your provider may send you for an MRI of the knee. This can confirm the diagnosis. It may also show other knee injuries.
First aid (/health-library/selfcare-instructions/anterior-cruciate-ligament-acl- injury-aftercare) for an ACL injurymay include:
- Raising your leg above the level of the heart
- Puttingice on the knee
- Pain relievers, such as nonsteroidal anti-inflammatory drugs (such as ibuprofen)
You also may need:
- Crutches to walk until the swellingand pain get better
- Braceto give your knee some stability
- Physical therapyto help improve joint motionand leg strength
- Surgery to reconstruct the ACL
Some people can live and function normally with a torn ACL. However, most people complain that their knee is unstable and may "give out" with physical activity. Unstable knee after ACL tears can lead to further knee damage. You are also less likely to returnto the same level of sports withoutthe ACL.
Do Not
- Do NOT move your knee if you have had a serious injury.
- Use a splintto keep the knee straightuntil you see a doctor.
- Do NOT return to play or other activities until you have been treated.
When to Contacta Medical Professional
Contact your provider rightaway if you have a serious knee injury.
Get immediate medicalattention if the foot is cool and blue after a knee injury. This means that the knee joint may be dislocated, and blood vesselsto the foot may be injured. This is a medical emergency.
Prevention
Use proper techniques when playing sports or exercising. Some
college sports programs teach athleteshow to reduce stress placedon the ACL. This involvesa series of warm up exercises and jumping drills. There are jumping and landing exercisesthat have been shown to reduce ACL injuries.
The use of knee braces during vigorous athletic activity (such as football) is controversial. It has not been shown to reducethe number of knee injuries,but not specifically ACL injuries.