Anterior Cruciate Ligament (ACL) Tear

What is an Anterior Cruciate Ligament (ACL) Tear?

The knee joint contains Cruciate ligaments. The anterior cruciate ligament (ACL) is in the front of the kneecap and the posterior (PCL) is in the back. These ligaments form an “X” because they run diagonally of each other. They control back-and-forth movements of the knee, stabilize rotational movement and create alignment for the tibia and the femur bone.

ACL tears are common in physical activities or sports that require sudden changes in direction or stopping, such as gymnastics, football, skiing, and tennis. During these injuries, patients often describe a popping sensation, followed by a rapid onset of pain, swelling, and instability.

Knee Ligaments 

  1. Collateral Ligaments

Collateral ligaments control sideways movements of the knee. These two ligaments are located on the inside and outside of the knee. The medial is on the inside and the lateral is outside the knee joint.

  1. Cruciate Ligaments

Cruciate ligaments control the knee’s back-and-forth motions and prevent rotational movements. These ligaments are located on the inside of the knee joint and as mentioned previously, form an “X” with the anterior ligament in the front of the knee and the posterior behind.

Types of ACL Injuries

ACL injuries are sprains or full tears, and there are three phases of these injuries classified in grades 1, 2 and 3. Other knee injuries often accompany ACL injuries, resulting from the same abrupt stopping, rapid direction changes, or trauma. Grade 3 ACL injuries are the most common, and they are the most severe, causing a complete tear of the ligament.

The Three Grades of ACL Injuries

  1. Grade 1 sprain. The ligament fibers are stretched but not torn. This may cause some pain, but it’s not unbearable and the knee joint is still stabilized.
  2. Grade 2 sprain. Some of the fibers are torn but others remain intact. This is a partial tear and will cause pain and instability of the knee joint, but it’s not a complete tear.
  3. Grade 3 sprain. This is the most common ACL injury and with it, all the ligament fibers are torn, resulting in a complete tear and break between the ligaments. The knee will not be supported, the knee joint is unstable, and it’s overall painful.


Anterior Cruciate Ligament (ACL) Tear Symptoms

ACL tear symptoms are generally the same for most individuals. However, additional injuries to the knee are common. For example, a meniscus tear, articular cartilage damage, and other ligament or tendon tears often occur alongside an ACL tear. These additional injuries can amplify the symptoms to varying degrees.

  • Limited range of motion. At the onset of the injury, the pain and instability due to the ligament tear will cause the knee to give out, and limited, if any, pressure can be applied.
  • Popping sensation in the knee. It’s common to feel a popping sensation and to audibly hear it as well with an ACL injury.
  • Swelling and pain. With the injury, it’s not uncommon for the knee to swell, due to the inflammatory response of the body, by sending white blood cells to the area. Fluid may soon begin to accumulate in and around the knee and it is a painful injury.
  • Instability. Due to the instability of the knee joint, it will be extremely difficult to walk and may require assistance.
  • Continual knee instability. After the ACL is healed or healing, it may still prevent the quality of support and stability that the knee once had. They may notice that this is the case when trying to run or pivot the knee. Many patients have persistent knee instability and are susceptible to re-injury.

Anterior Cruciate Ligament (ACL) Tear Causes

There are numerous causes of ACL tears, but it’s common in athletes and those who are physically active.

  • Sudden change in direction. In basketball, when the player dribbles the ball and tries to trick the opponents, they will use a technique known as cutting. This is when they change direction abruptly. This and similar movements are often the cause of many ACL tears. 
  • Pivoting. When individuals pivot direction, especially in sports, these movements often torque the knee and tear the ACL.
  • Jumping to an awkward landing. In gymnastics, we often see athletes try to stick the landing but land awkwardly and tear their ACL. This can happen in any haphazard jumping and tripping incident.
  • Stopping suddenly. If a runner is going along at a certain pace and then slows down or quickly stops, it can cause an ACL tear due to the jarring motion and buckling of the knee.
  • Direct blow to the knee. When an accident or trauma directly hits the knee, it often results in an ACL tear.

Risk Factors for Anterior Cruciate Ligament (ACL) Tear Condition

ACL tears are common, and the onset of the tear is usually the cause of injuries from sudden movements, especially those of pivoting motions or changing direction. Basketball and volleyball players often experience torn ACLs, as do athletes that make quick movements.

Risk factors include:

  • Suddenly and abruptly shifting direction
  • Abruptly stopping running
  • Repeated stress to the knee
  • Hit to the knee
  • Falling or jumping up with a torqued knee can cause the ACL to tear.
  • Being female increases the risk of ACL tears due to differences in anatomy, muscle strength, and control.
  • Participating in certain sports and activities, such as soccer, football, basketball, dance, etc.
  • Poor-fitting footwear can cause falls and instability in the knee

How to Diagnose an Anterior Cruciate Ligament (ACL) Tear

The onset of pain, swelling, and instability signals a problem with the knee, making it crucial to seek medical care promptly. Early diagnosis and treatment of ACL tears lead to better outcomes for patients.

Orthopedic surgeons diagnose ACL tears through a physical examination and utilize diagnostic tests, including X-rays, magnetic resonance imaging (MRI), and ultrasound.


ACL Treatment

Depending on any other coexisting knee injury, the health of the patient and the age of the patient, treatment may vary. ACL full-thickness tears will not heal on their own and require surgery to rebuild it with grafted tissue. However, for the elderly and patients who live inactive lifestyles, conservative treatment may be sufficient. This includes bracing, physical therapy, pain medications, limiting function and weight-bearing.

Doctors typically recommended surgery for ACL tears. Grafts are often taken from the patient’s own tendons, these will help to rebuild the ACL. New tissue will naturally grow over time and cause it to become more stable.

With decades of experience, at Sforzo | Dillingham | Stewart Orthopedics + Sports Medicine all of our surgeons are board-certified, and fellowship-trained. We offer you the best treatment options and care.