The anterior cruciate ligament (ACL) is one of the main ligaments of the knee, which is essential for the stability of this joint. Located inside the knee, it constitutes, together with the posterior cruciate ligament, the central pivot of this joint, controlling the displacements of the tibia over the femur, both anteroposteriorly (avoiding the forward displacement of the femur over the tibia) and rotationally (stabilizing the knee during knee rotations).
The ACL is the most important anatomical structure for rotational stability of the knee. It is common for patients who suffer an ACL injury (isolated, without meniscus or articular cartilage injury), after the acute moment has passed and the inflammation has disappeared, to be able to walk, climb stairs and jog without pain. This is possible because the ACL is not important for walking, but for knee rotation and stability. This answers a question that patients ask very often, after confirming the diagnosis in consultation and with MRI: “How can I have a torn ACL if I can walk without difficulty and without pain?”
How do we know that the anterior cruciate ligament is torn?
In the first hours after traumatic ACL injury, local swelling and pain occur. In some cases, when the joint effusion (fluid inside the joint) is important, it can produce great pain and an evacuating puncture (fluid extraction) would be indicated, in which case we will find that the fluid is blood. A hemarthrosis (blood in the joint) in this context, supposes in more than 80% of the cases a rupture of ACL.
In the diagnosis, clinical examination should prevail over complementary tests, such as X-rays or magnetic resonance imaging. This is because the examination of an expert professional has much more value, especially when more than one month has passed since the accident, since the complementary tests can present false negatives (complementary tests within normality) four weeks after the accident.
Is anterior cruciate ligament rupture frequent?
ACL injury is common in athletes, with a higher incidence in contact sports such as soccer, rugby, basketball or skiing. These practices require abrupt changes of direction or turns, being this ligament responsible for retaining the knee during braking, acting in these changes of direction and in the reception of the jump. In most cases, the injury occurs without direct contact on the knee.
This is a very important injury for this joint and, until recently, it had a very poor prognosis, which has been improving in recent decades due to the introduction of minimally invasive techniques such as arthroscopic reconstruction, which today is the gold standard.
Female athletes have a higher rate of ACL tears, between 2 and 8 times more than men who practice the same sport. This is due to several factors such as:
- Pelvic dimensions
- Different morphology of the knee (Q angle)
- Greater joint laxity
- Less protection of the muscles over the knee
- Hormonal status