ACL Injuries: The basics

What is an ACL injury?

The anterior cruciate ligament (ACL) is one of the four main ligaments of the knee. The ACL provides about 90% of the knee’s stability on its own, despite its small size relative to the other ligaments of the knee. ACL injuries occur when the ACL is subjected to extreme force, it can become strained, partially torn, or even fully separated. 


What Causes an ACL injury?

The most common time for ACL injuries to occur is during competitive sports. Rapid direction changes, like those found in sports such as soccer, basketball, football, and tennis, are the number one risk factor for ACL injuries.

Although ACL injuries are most often caused by sudden changes of direction overloading the ligament, ACL injuries can also occur during regular activity. All it takes is a bad landing, slip or fall, and there is a possibility that your ACL will pay the price.


The Signs and Symptoms of a Torn ACL:

Immediate Signs:

Severe pain in knee

A significant ‘pop’ at the time of injury

An inability to straighten or bend the knee all of the way.

Severe swelling

Types of ACL Injuries

There are three different grades of ACL injury, each indicating a different severity of strain or tear. Below are the different kinds of ACL injuries, the severity of injury, and some basic symptoms.


Grade I (Stretched Ligament)

The ligament is stretched too far but is not torn.

Knee is sore and tender, partial swelling may occur.

No significant impact on mobility and stability.


Grade II (Partially Torn Ligament)

The ligament is partially torn.

Moderate pain and swelling.

Unstable feeling in knee, may give out during any activity


Grade III (Completely Torn Ligament)

The ligament is completely torn into two parts.

Sore, painful knee, moderate to severe swelling.

The knee is unstable and can not bear weight effectively.




What should you do if you are injured?

The best thing to do if you suspect you have injured your ACL is to follow the RICE (Rest, Ice, Compression, and Elevation) protocol and immediately contact your doctor. If you suspect that your injury is severe, stay off of the knee until you see a medical professional. Further use could aggravate the injury. If your injury is probably not severe, it is still advisable you get in contact with your doctor so they can assist you on your path to recovery.


The RICE Protocol:

Rest: Stay off your knee! Keep weight off of your injured knee and allow it to rest.

Ice: Apply a cold pack or ice to reduce existing swelling and prevent additional swelling.

Compression: Use an elastic bandage or athletic tape to wrap the afflicted knee gently yet firmly. You should feel pressure, but do not wrap so tight as to cut off circulation. Loosen the wrap if you feel numbness or tingling.

Elevation: Keep the afflicted knee above heart level when sitting or laying down whenever possible.

Remember, the RICE protocol is most effective in the first 72 hours after injury. Be diligent early on and take care of yourself properly until you can seek further personalized advice from your doctor.