Anterior Cruciate Ligament (ACL) Tear

The anterior cruciate ligament (ACL) is one of the main stabilizing ligaments in the knee. It is a ligament that connects the thigh bone to the leg bone. Your ACL controls abnormal motion during cutting, turning, and pivoting actions required during athletic activity.


ACL injury typically occurs during athletics where jumping, pivoting and rapid change of direction occurs. Football, basketball, lacrosse, soccer, and skiing are some sports known to have high ACL injury rates. Contrary to popular belief, the ACL can tear without contact. In this case the ligament, which is made of dense fibrous tissue, fails with a twisting mechanism. This non-contact injury occurs more commonly in female athletes.


Typical symptoms include:

  • Pain
  • Immediate difficulty with walking
  • Sensation of knee instability
  • Immediate swelling
  • Popping sound at the time of injury


The treatment of ACL tears is highly individualized. After the ACL tears, it has a very poor blood supply and the ability for the ligament to heal is limited. A well-trained orthopedic sports medicine physician can make an accurate diagnosis by doing an exam that tests the competency of this ligament. The physician will usually obtain X-rays to check for any small fractures, but often an MRI is obtained. The MRI will confirm the tear of the ACL but more importantly will check for the presence of other soft tissue injuries to the knee known to occur with an ACL tear.

Some patients will require surgery while others can be treated with non-surgical methods, including bracing and knee rehabilitation. The decision for treatment should be a discussion between you and your surgeon examining all the injuries that have occurred, the demands of the patient, and athletic and work requirements. In a general sense, patients who wish to remain highly athletic, have torn cartilage, or are not willing to change their active lifestyle will be candidates for surgery.

Considering that the ACL has limited ability to heal, simply sewing the torn ends will not be successful. Modern ACL surgery requires the use of another tendon called a “graft” to be used to substitute for the torn ACL. These grafts are inserted into the knee with the use of an arthroscope, which is a very small lens that’s placed into the knee joint and is connected to a camera and monitor so the surgeon can examine and operate on the knee with less invasive techniques.

When patients choose non-operative treatment, the most common complication is recurrent knee instability. This means that the knee is not reliable, may give out with turning sports, and has the small risk of causing increasing damage to the joint surface and cartilage.

Rehabilitation after surgery will focus on restoring range of motion, protecting the surgery, and minimizing muscle atrophy. Typically, a brace and protected weight-bearing crutches are utilized for several weeks. You will then progress to strengthening exercises and more sport-specific training. Most patients are allowed to return to sports between 7 to 9 months, however, the use of a brace when returning to sports is individualized. There is no scientific evidence that braces prevent ACL injury.