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ACL Injuries

There are three bones that make up the knee joint – the femur or thigh bone, the tibia or shin bone, and the patella or kneecap. There are two cruciate ligaments (ACL and PCL) inside the knee joint that cross to form an X. Together, they help control the front-to-back motion of the knee, as well as rotation.

What is the ACL?

The Anterior cruciate ligament (ACL) is one of two cruciate ligaments that cross form the X. The ACL sits in front of the knee joint while the posterior cruciate ligament (PCL) sit in the back.

ACL Anatomy

ACL Anatomy

ACL Hemi Knee LAT

How does the ACL work?

The purpose of the ACL ligament is to prevent the tibia (the shin bone) from sliding in front of the femur (the upper leg bone), and to stabilize the knee during rotation. The ACL ligament also contains important nerve fibers that can tell your brain where your knee is positioned as well as vessels that help with the nutrition of the ACL.

How do injuries to the ACL occur?

Traumatic Injury to the ACL occurs in athletes who participate in high-risk sports such as skiing, soccer, football and basketball. The majority of ACL injuries result from a sharp twisting of the knee, sudden deceleration while cutting, pivoting, and sidestepping movements, sudden stopping when running, and awkward landing from a jump. Other causes include direct contact, a fall or traumatic accident. Women who participate in college sports, such as: soccer, basketball, softball, lacrosse, rugby are four times more likely than men to rupture their ACL.

ACL Tear Illustration

ACL Tear

What are the symptoms of an ACL injury?

When you injure your ACL, you may hear a “pop” at the time of injury coupled with buckling of the knee. There will be immediate and intense knee pain, swelling, inflammation, redness, and bruising. The pain may resolve, but the knee may remain unstable, and there may be a loss of knee range of motion. Continuing regular activities with the unstable knee may cause more damage to other structures such as the meniscus and cartilage. Other symptoms can include tenderness along the knee joint (if there is an associated meniscus tear), buckling of the knee, and difficulty with walking.

Can an ACL injury heal on its own?

Yes, some ACL injuries can heal without surgery, especially incomplete injuries or what may be described as a sprain or partial tear. Even for complete tears of the ACL, conservative treatment (meaning no surgery) can potentially be successful in patients who do not intend to return to pivoting activities, and for some patients that are willing to wear a brace to control instability while playing sports that require pivoting activities. However, patients with goals to return to high-risk sports will need surgical reconstruction.

Severity of ACL tears (rupture)

Grade 1 ACL Sprain:

ACL injuries that stretch the ligament can heal on their own with conservative treatment including rest, ice, compression, elevation, and anti-inflammatory medications.

Grade 2 Partial ACL tears:

ACL injuries that tear some of the ligament fibers are called “partial tears” and may heal with conservative management including physical therapy. When instability persists, bracing can be used to return to low-demand sports and daily activities. The decision to perform surgery to fix a partial tear depends on the severity of instability of the knee, and patient’s desire to return to the sport that resulted in the injury.

Grade 3 Complete ACL tears:

A complete tear of the ACL describes an injury in which the ligament is non-functional and will require surgery to fix it. Professional athletes and the majority of recreational athletes will likely require surgery to return to play.

What is the most accurate way to diagnose an ACL injury?

The combination of a detailed history, comprehensive physical examination, x-rays, and an MRI (magnetic resonance imaging) are the keys to successful diagnosis of injuries to the ACL. Because almost half of all ACL injuries occur in combination with other knee injuries, imaging studies such as MRI are important to evaluate the full extent of your injuries. In addition to MRI imaging, Dr. Jorge Chahla uses stability tests as part of his physical exam, including as the Lachman and Anterior Drawer Tests to properly diagnose an ACL Injury.

What is the best time to fix an ACL injury?

Studies report that patients with an ACL injury may benefit from beginning with physical therapy to strengthen the muscles surrounding the knee (prehabilitation), particularly when their range of motion is limited, followed by surgical reconstruction. Generally, delaying surgery until the pain, swelling and inflammation have decreased, and the range of motion has been restored with physical therapy, results in the best outcome. The timing of ACL surgery is made on a case-by-case basis with each individual patient.

How is an ACL injury fixed?

Knee arthroscopy is a minimally invasive procedure used to view, assess, and treat a torn ACL. ACL reconstruction involves the replacement of the ruptured (torn) ligament with a tendon graft. Graft tissue is either taken from the patient (autograft) or taken from a tissue donor (allograft). A torn meniscus, commonly found with an ACL rupture, can also be repaired during Knee arthroscopy.

ACL Reconstruction

The source of the graft tissue and the technique depend on the severity of the injury, age and activity level of the patient, desired outcome, and Dr. Chahla’s preferred method. Bone-patellar tendon-bone (BTB) autograft ACL reconstruction has the longest proven track record of successful outcomes, and is the technique to which all others are compared. Other options include the hamstring tendons (semitendinosus and gracilis) along the inner part of the thigh and knee. More recently, the quadriceps tendon has gained popularity as a graft source for ACL reconstruction; however, further data is necessary for a more widespread use.

How long is the recovery?

Recovery from an ACL reconstruction takes an average of 6-9 months including full rehabilitation to restore range of motion, strengthen the muscles, and recover balance. Furthermore, injury prevention after completing the rehabilitation remains of utmost importance to prevent subsequent injuries.

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Schedule an orthopedic consultation

When you are in need of an orthopedic knee surgeon in Chicago, schedule a consultation with Dr. Jorge Chahla. You’re in expert hands. Dr. Chahla is a nationally renowned, award-winning, fellowship-trained, and board-certified orthopedic surgery in Chicago. Dr. Chahla has orthopedic clinics in Chicago, Naperville, Oak Brook, and Munster Indiana.

At a Glance

Dr. Jorge Chahla

  • Triple fellowship-trained sports medicine surgeon
  • Performs over 500 surgeries per year
  • Assistant professor of orthopedic surgery at Rush University
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