What is an ACL?

The anterior cruciate ligament (ACL) is located in the central part of the knee, inside your knee joint. These ligaments control the back and forth movements of your knee.

The main function of the ACL is to protect excessive motion at the knee joint.  It prevents the tibia from sliding out in front of the femur, as well as provides rotational stability to the knee.a

ACL Injury

ACL-InjuryAn ACL injury tear or sprain of the anterior cruciate ligament. These type of injuries typically occur in sports due to the sudden stops or changes in direction. Soccer, basketball, football and downhill skiing are among the most common of this injury.

When an ACL injury occurs, there is typically a pop like sound in the knee. Your knee may feel unstable and swelling is possible. In some instances, it may become too painful to bear weight.

About half of all injuries to the anterior cruciate ligament occur along with damage to other structures in the knee, such as articular cartilage, meniscus, or other ligaments.

Symptoms of an ACL Injury

The signs and symptoms of an ACL injury include the following:

  • A loud “pop” or a “popping” sensation in the knee
  • Severe pain and inability to continue being active
  • Rapid swelling
  • A feeling of instability or “giving way” with weight bearing
  • Loss of range of motion

ACL Injury Causes

ACL Injuries often occur during sports and fitness activities, when stress is put on the knee.

There are a number of risk factors which increase your risk of an injury. Which include the following:

  • Sex: Being female
  • Playing sports: Participating in certain sports, such as soccer, football, basketball, gymnastics and downhill skiing put you at risk.
  • Weightlifting: Improper form could put you at risk for an injury when working out
  • Improper footwear: Footwear that does not fit properly
  • Poorly maintained equipment

ACL Injury Treatment

In the case of a partial tear or acute isolated injury to the ACL conservative management may be considered as first-line treatment. 


When treating an injury such as this one, it is often suggested to take x-rays, MRI, or an ultrasound to see how bad the tear is.

Additionally, treatments may include physical therapy, anti-inflammatory medications, bracing and possibly corticosteroid injections can be effective in managing symptoms. 

It’s typical for your physician to put you on bedrest with ice, compression, and elevation to reduce the swelling.


In the event of significant laxity with mechanical symptoms or failure of conservative management surgical treatment may be recommended to help restore function and mobility and promote a return to activity.

ACL Reconstruction: During this surgical procedure, the surgeon will remove the ligament and replace it with a segment of a tendon. Next, the surgeon will take a piece of tendon from another part of your knee and replace it.

After surgery, physical therapy is necessary to regain stability and function of your knee.