Health Library
ACL (Anterior Cruciate Ligament) Tear

What is an ACL (Anterior Cruciate Ligament) Tear?

kneeFour main ligaments hold the knee joints together:

  • The medial collateral ligament
  • Lateral collateral ligament
  • Anterior cruciate ligament (ACL)
  • Posterior cruciate ligament

The cruciate ligaments cannot heal once they are torn.

ACL tears occur two to six times more often in females than in males doing the same amount of sports activities.

Due to the higher level of male participation in contact and collision sports, though, the number of cruciate ligament injuries is higher in males.

ACL injuries can be linked with injuries to the cartilage in the knee. This can complicate matters.

Causes of ACL Injury

The cause of most ACL tears is a sudden, abrupt change in force to the knee. This can occur during an unexpected cutting move during sports, or when landing from a jump during basketball. Recent evidence shows that most of these injuries are non-contact and do not involve a collision with another player.

Signs and Symptoms of ACL Injury

Most often, the knee gives out, and the athlete hears a pop and falls in agony. Most athletes with an ACL tear cannot keep playing and must be helped off the field or court. The knee usually swells very quickly.

At the emergency room, X-rays are taken. These usually come back normal, with swelling on the knee. The diagnosis is often a knee sprain, and the athlete is placed in a knee brace. They are told to follow-up with a sports medicine specialist in the next few days.

Treatment for ACL Injury

The initial treatment consists of:

  • Ice during the first 24 to 48 hours (one to two days)
  • Elevation
  • Rest
  • Compression (such as an ACE wrap)
  • Keeping the knee from moving by applying a knee brace.
  • Crutches are usually needed.
  • Pain medicine (such as ibuprofen or acetaminophen) is often advised.

The patient may have to miss a few days of school after the initial injury.

Most young athletes who want to continue playing sports like, basketball, soccer, volleyball, football and wrestling, choose to have ACL reconstruction surgery. Without surgery, a person with a torn ACL is at risk for repeated knee instability. Each time the knee gives out, there is a risk of increased damage to the cartilage in the knee. This is very hard to repair and can cause arthritis later in life.

Because the ACL will not heal even if it is repaired, a nearby tendon is used as a substitute for the torn ACL tendon. This is why the procedure is called a reconstruction. An adult-style ACL reconstruction goes through the growth plates of the leg bone (tibia) and the thigh bone (femur). This may not be appropriate for children and young teens. Children and teens, who still have a lot of growth in their knees, are at some risk for a slowing of growth if standard ACL surgery is done before they are finished growing. We have co-developed an “All epiphyseal” ACL reconstruction for children that restores normal anatomy and function. It does not touch or cross the growth plates, and minimizes the risk of knee growth problems.

The chance of stopping a child’s growth after ACL reconstruction in young patients is a rare complication. Once a teen’s ACL is reconstructed, they can usually return to the prior level of sports competition without any more episodes of instability.

A pre-operative treatment program usually consists of:

  • Aggressive rehabilitation with strengthening of the knee muscles
  • Regaining range of motion
  • Controlling swelling

A brace can help provide support, but patients waiting for reconstruction should avoid basketball, soccer, wrestling, football and volleyball.

Caring for ACL after Reconstruction Surgery

After surgery, a patient can usually walk on the affected leg as tolerated. There are no limits in motion. The patient starts physical therapy the three to seven days after surgery. They may return to sports when he or she has greater than 90 percent strength in the leg. This is usually six to nine months after surgery.

Preventing ACL Injury

Neuromuscular training (learning how to land properly from jumps) may reduce ACL injuries in females.

Call Your Child's Doctor If:

Call your child's pediatrician, family doctor or orthopaedic doctor if:

  • Severe pain continues despite pain medicine
  • Your child develops pain, numbness or coldness in the leg
  • The knee keeps giving out

Last Updated 03/2022

Reviewed By Gertrude Whitaker, RN

Learn more about the Sports Medicine team of specialists.

The Division of Sports Medicine is home to specialists with a wide variety of backgrounds and areas of focus who are prepared to care for your child's unique needs. 

Contact us.