Anterior Cruciate Ligament (ACL) Injury

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What is an ACL injury?

The anterior cruciate ligament (ACL) is one of the major ligaments in the middle of the knee. It connects the femur to the tibia. This ligament helps keep the knee stable and protects the femur from sliding or turning on the tibia. ACL injuries graded as grade I, II, or III sprains.

Grade I: Pain in the knee with minimal damage to the ligament.
Grade II: More damage to the ligament and mild looseness of the knee.
Grade III: The ligament is completely torn and the joint is very loose and unstable.

How does an ACL injury occur?

The ACL is frequently injured in forced twisting motions of the knee. It may also become injured when the knee is hyperextended. An ACL injury sometimes occurs when the thigh bone is forcefully pushed across the shin bone, such as with a sudden stop while you are running or a sudden transfer of weight while you are skiing.

What are the symptoms of an ACL injury?

There is usually a loud, painful pop when the ACL is first injured. This is often followed by a lot of swelling in the knee within the first several hours after the injury. This swelling is called an effusion and is made up of blood in the knee joint. If your ACL injury occurred months or years ago and you have not had reconstructive surgery, you may have the feeling that your knee is giving way during twisting or pivoting movements.

How is an ACL injury diagnosed?

Your doctor will examine your knee and may find that your knee has become loose. Your doctor will order an x-ray to determine if there is an injury to the bones of your knee. An MRI will be ordered and should clearly show the condition of you ACL.

How is an ACL injury treated?

Initial treatment will include the following:

  • Ice Therapy
  • ACE bandage
  • Use crutches
  • Elevation
  • Wear a knee brace
  • Home exercises

Further treatment may include reconstructive surgery to repair the ACL. Following surgery you will complete a course of intense physical therapy and rehabilitation.

Information obtained from The Sports Medicine Patient Advisor by Pierre Rouzier, MD