What is an anterior cruciate ligament (ACL) tear?
The anterior cruciate ligament (ACL) is one of two cruciate ligaments that stabilize the knee joint. It is a strong band made up of connective tissue and collagen fibers that originates from the anteromedial area of the tibial intercondylar region and extends posterolaterally to attach to the medial surface of the lateral femoral condyle, where two important landmarks are located. The ACL is 32mm long and 7 to 12mm wide. It has two bundles — an anteromedial bundle and a posterolateral bundle — with the latter showing more flexible changes in length.
According to research, the anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee, accounting for nearly half of all knee injuries. The reported annual incidence in the United States alone is about 200,000 people, more than half of whom require surgical intervention.
ACL tears can occur at any age or in either sex; however, several statistics indicate that women have a higher risk of secondary ACL injury due to a number of factors.
Causes of ACL tears
The main causes are sudden movements, twisting of the knee, and hyperextension of the knee joint, or sudden, strong, and fast impact to the knee.
Among athletes, the rate of ACL injury in women versus men is 4.5 to 1. Female athletes tend to tear their ACL at a younger age and more often than male athletes. However, in general, men also carry a risk of ACL tears similar to women.
Factors that increase the risk of ACL tears in women:
Women's knee joints have weaker hamstring muscles, so during activity, the body tends to prioritize the quadriceps muscles when decelerating. Engaging the quadriceps while slowing down during running places abnormally increased stress on the ACL, because the quadriceps are less effective than the hamstrings at preventing forward displacement of the tibia.
Landing biomechanics in women may increase the risk of ACL injury due to increased knee valgus angle and knee extension.
Other risk factors that can increase injury risk include higher body mass index, a smaller femoral notch, notch impingement, a smaller ACL, hypermobility, joint laxity, and previous ACL injury.
In addition, the ACL can tear due to various other causes:
High-intensity activity: Sports or work involving high intensity can create large pressure on the ligament, leading to injury.
Sudden trauma: Strong kicks, pushes, or collisions can tear the ligament.
Symptoms of an ACL tear
Recognizing symptoms early can help you respond quickly. Common symptoms include:
Acute pain: intense pain at the injured area.
Swelling and redness: the injured area swells and may appear red or flushed.
Limited movement: reduced mobility of the injured area, an inability to extend or bend the knee joint.
Knee injury – when should you see a doctor?
When you sustain a knee injury, you should stop all activities that put pressure on the injured area. Apply ice wrapped in a towel or a specialized cold pack to the injured area and use light compression bandaging.
If advised by a doctor, you may use pain relievers and anti-inflammatory medication. After a period of rest, perform gentle movements to maintain flexibility if possible.
If symptoms do not improve or worsen, you should see a doctor as soon as possible for proper evaluation and treatment.
Is a torn ACL in the knee dangerous?
Most ACL tears occur in athletes through a non-contact mechanism — a non-contact rotational injury in which the tibia shifts forward while the knee is slightly bent and in a valgus position. Soccer players carry the highest risk of injury; if left untreated for a long time, it can affect the ligaments, meniscus, and knee joint.
A chronic ACL tear can have harmful effects on the knee, leading to the development of cartilage damage and complex meniscal tears that cannot heal, and an increased risk of meniscal tears.
Recovery time varies from person to person. Depending on the injury, doctors may prescribe medical treatment or surgical intervention, combined with physical therapy to help restore knee joint strength.
A torn ACL in the knee can cause significant inconvenience, but with early and proper treatment, you can recover. At the Trauma and Orthopedics Unit – General Surgery Department – HIU Hospital, for knee injuries, specialist doctors will conduct a direct examination, coordinating with the Diagnostic Imaging and Functional Exploration Department to accurately assess the extent of the knee injury. The patient will then be given an appropriate treatment plan to help restore mobility and return to normal life as soon as possible.