ACL Tear

The anterior cruciate ligament (ACL) is one of four primary ligaments stabilizing the knee joint. Situated in the center of the knee, it connects the femur (thighbone) to the tibia (shinbone) and plays a vital role in controlling forward and rotational movements of the knee. An ACL tear occurs when the ligament is stretched or torn, often resulting in instability of the knee joint. Tears can range in severity from partial tears to a complete rupture.

ACL injuries are among the most common knee injuries, particularly in athletes involved in sports requiring pivoting, jumping, or sudden changes in direction. While these injuries are prevalent in high-contact sports like football, they are also common in non-contact sports such as soccer, basketball, and skiing.

The primary mechanisms leading to an ACL tear typically involve rapid, forceful movements that stress the knee joint beyond its capacity. These mechanisms include:

1. Sudden Direction Changes: Sports that involve abrupt cutting or pivoting, such as basketball or soccer, can strain or tear the ACL.
2. Improper Landing Techniques: Jumping and landing with inadequate knee alignment can generate excessive force on the ACL, causing a tear.
3. Direct Impact: Collisions or tackles, as seen in football, can result in an ACL tear, particularly when the knee is hyperextended or forcefully twisted. A common scenario is when the knee strikes the dashboard during a collision, causing a forceful blow to the joint.
4. Overuse and Fatigue: Repetitive strain on the knee joint over time can weaken the ACL, increasing the risk of injury during physical activity.
5. Biomechanical and Anatomical Factors: Certain factors, such as a narrow intercondylar notch (where the ACL is housed), poor neuromuscular control, or muscle imbalances, can predispose an individual to ACL injuries. Women are at a higher risk due to hormonal influences and differences in anatomy and biomechanics.

An ACL tear typically results in immediate symptoms that indicate significant injury to the knee, including:

1. A Popping Sensation: Many individuals report hearing or feeling a “pop” at the moment of injury.
2. Severe Pain: Pain is often sudden and intense, typically preventing the individual from continuing activity.
3. Swelling: Rapid swelling occurs within hours due to bleeding into the joint.
4. Instability: The knee may feel unstable or as if it is “giving out,” or actually giving out with weight bearing.
5. Limited Range of Motion: Stiffness and difficulty bending or straightening the knee are common following an ACL tear.

While some individuals may try to continue activity after the initial injury, symptoms often worsen as swelling and instability progress. Untreated ACL tears can lead to further damage to surrounding structures, including the meniscus (the shock absorber in the knee) and cartilage, increasing the risk of long-term complications like osteoarthritis.

Accurate diagnosis of an ACL tear involves a thorough evaluation by an experienced orthopedic specialist like Dr. Stephanie Boden. She will begin by discussing the circumstances surrounding the injury, such as the type of activity, the mechanism of injury, and the onset of symptoms. This information provides crucial clues for diagnosing an ACL tear.

Dr. Boden will provide a thorough physical exam of the knee assessing for swelling, tenderness, range of motion, and signs of instability. Specific tests are performed to evaluate the integrity of the ACL. She will order imaging studies to diagnosis and assessing the extent of the injury including X-rays to help rule out fractures or other bony injuries that may occur alongside an ACL tear. An MRI is the gold standard for visualizing soft tissue structures in the knee, including the ACL, meniscus, and cartilage. It provides detailed images to confirm the tear and evaluate any associated injuries. She will also perform functional tests to evaluate the knee’s stability and strength.

Prompt diagnosis and treatment of ACL tears are essential to preventing further injury and ensuring optimal recovery. Left untreated, an ACL tear can lead to chronic knee instability, putting the individual at greater risk of additional injuries and long-term joint degeneration.