Anterior Cruciate Ligament

Anterior Cruciate LigamentThe ACL is one of the four main ligaments in the knee joint that connect it to the shinbone (tibia) and thighbone (femur). It’s located deep within the joint, behind the kneecap (patella), above the shinbone, and below the thighbone.

The ACL works with the PCL (posterior cruciate ligament), which crosses over it to form an “X.” Together, these two ligaments help keep the knee stable when rotating. The ACL keeps the shinbone in place and prevents it from moving too far forward and away from the knee and thighbone.

Anterior cruciate ligament injury

Anterior cruciate ligament injury occurs when the biomechanical limits of the ligament are over-stretched. It is an important internal stabilizer of the knee joint. The primary function of the anterior cruciate ligament is to prevent hyperextension; its secondary purpose is to restrain tibial rotation and varus stress. ACL injury is most commonly a non-contact injury involving a sudden stop or twisting movement, such as a dismount from a layup in basketball, soccer.

ACL injury occurs more often in athletes than in the general population and is prevalent in alpine skiing, soccer, football, etc. It is about two times more common in women than men. The consequences of the ACL injury depend on how much the stability of the knee is affected, and the extent to which other structures have been involved. If instability is evident, particularly rotatory instability, then the meniscus may get injured; this may lead to degenerative, arthritis of the knee.

An ACL injury can occur:

  • When you hit very hard on the side of your knee, at the time of a football and soccer tackle. Overextend your knee joint.
  • If you Quickly stop moving and change direction while running.
  • You land from a jump or turn.
  • Universal sports linked to ACL tears include Basketball, football, soccer, and skiing.


  • A “popping” sound at the time of injury.
  • Knee swelling within 6 hours of injury.
  • Pain, especially when you try to put weight on the injured leg.
  • Those who have only a mild injury may notice that the knee feels unstable or seems to “give way” when using it.


  • Do NOT move your knee joint if you have had a serious injury.
  • Use a splint to keep the knee joint straight until you see a doctor.
  • Do NOT back to play or other activities.

Nonsurgical Treatment

In nonsurgical treatment, physical therapy and rehabilitation can restore the knee to a condition close to its pre-injury state and educate the patient on how to prevent instability.
This may enclose with the use of a hinged knee brace. However, many people who choose not to have surgery may experience secondary injury to the knee due to repetitive instability episodes.

Surgical treatment is usually advised in dealing with combined injuries. However, deciding against surgery is reasonable for some patients. Nonsurgical management of isolated ACL tears is eventually to be successful or may be indicated in patients:

  • With partial tears and no instability symptoms.
  • With complete tears and no symptoms of knee instability during low-demand sports who are willing to give up high-demand sports.
  • Who do light manual work or live sedentary lifestyles
  • Whose growth plates are still open (children).

Surgical Treatment

Anterior cruciate ligament tears did not usually repair using a suture to sew it back together. Because repaired ACLs have generally shown a failure over time. Hence, the torn ACL needs replacement by a substitute graft made of tendon.

The grafts commonly used to replace the ACL include:

  • Patellar tendon autograft
  • Hamstring tendon autograft
  • Quadriceps tendon autograft
  • Allograft patellar tendon, Achilles tendon, semitendinosus, gracias, or posterior tibialis tendon
  • Patients treated with surgical reconstruction of the ACL have long-term success rates of 82 percent to 95 percent.
  • Recurrent instability and graft failure.

The goal of the ACL reconstruction surgery is to prevent instability and restore the function of the torn ligament, creating a stable knee. This allows the patient to return to sports. There are certain factors that the patient must consider when deciding for or against ACL surgery.