Ligament Tears – Anterior Cruciate Ligament (ACL)

The knee is the largest joint in the body and is vital to movement. The stability of the knee mostly depends on the ligaments and muscles around it. Therefore, injuries to knee ligaments are common. In 2006, more than 12 million people visited orthopaedic surgeons because of knee problems.

Two sets of ligaments in the knee give it stability: the cruciate ligaments and the collateral ligaments.

Cruciate Ligaments

The cruciate ligaments are located within the knee joint and connect the thighbone (femur) to the shinbone (tibia). They function like short ropes that hold the bones of the knee joint tightly together when the leg is bent or straight. This is needed for proper knee joint movement.

The cruciate ligaments are so named because they cross each other to form an “X.” The term cruciate comes from the Latin word crux, which means “cross.”

The cruciate ligament located toward the front of the knee is the anterior cruciate ligament (ACL). The cruciate ligament located toward the rear of the knee is the posterior cruciate ligament (PCL).

ACL Injuries

The ACL prevents the shinbone from sliding forward beneath the thighbone.
The ACL can be injured in several ways:

  • Changing direction rapidly
  • Stopping suddenly
  • Slowing down while running
  • Landing from a jump
  • Direct contact or collision, such as in a football tackle


If you injure your ACL, you may not feel any pain immediately. However, you might hear a popping noise, and you may feel your knee give out from under you.

Within 2 to 12 hours, the knee will swell, and you will feel pain when you try to stand. Apply ice to control the swelling, and elevate your knee until you can see an orthopaedic surgeon.

If you walk or run on an injured ACL, you can damage the cushioning cartilage in your knee. For example, if you plant your foot and then turn your body to pivot, your shinbone may stay in place as your thighbone above it moves with the rest of your body.


Diagnosis of an ACL injury is based on a thorough patient history and physical examination of the knee. The examination may include several tests to see if the knee stays in the proper position when pressure is applied from different directions.

Your doctor may order an X-ray and/or a magnetic resonance imaging (MRI) scan of the knee. In some patients, arthroscopic inspection of the knee joint is required.


A partial tear of the ACL may or may not require surgical treatment. A complete tear is a more serious injury. Complete tears, especially in younger athletes, may require reconstruction. Both nonsurgical and surgical treatment options are available for ACL injury.

Nonsurgical Treatment

Nonsurgical treatment may be used because of a patient’s age (very young or elderly) or overall low activity level. It may be recommended if the overall stability of the knee is intact. Nonsurgical treatment involves a program of muscle strengthening, often with the use of a functional brace to provide stability. Activities should be modified to limit cutting or pivoting movements.
Maximum Medical Improvement 6-8 weeks

Surgical Treatment

Surgery involves reconstruction of the damaged ligament using a strip of tendon from the patient’s own knee (patellar tendon) or hamstring muscle (Autograft). Allograft (cadaver tissue) reconstruction is also available. Graft options will be discussed with your doctor prior to the operation. Surgery is followed by an exercise and rehabilitation program to strengthen the muscles and restore full joint mobility. Full recovery and return to sporting activity is estimated at 4-6 months.

Maximum Medical Improvement 4-6 months
Work Status until MMI – Light duty avoid torsional activities