Understanding the Knee: ACL Sprain

What is it?  

First of all, we must understand what our ligaments are used for and especially what is the anterior crusader. A ligament is a strong but flexible band that connects two bones in a joint. The ligament plays a role of passive stability by limiting excessive movements in unwanted directions.

However, the role of a ligament is not limited to passively ensuring the stability of a joint. Our ligaments have several nerve endings that are, in fact, receptors that inform us about the position of our joint in space; what is called proprioception. These receptors send signals that travel through our nervous system to our brain. Following analysis of these signals, the brain sends a command to the muscles around the joint to control the joint and avoid excessive movements that could lead to injury.

The anterior cruciate ligament connects the femur to the tibia. Its role is to limit forward shearing of the tibia relative to the femur and, using the posterior cruciate ligament, to limit excessive knee torsion.


Who could have it?  

Knee ligament injuries are common injuries found in athletes of all ages. The anterior cruciate ligament is most often reached by an injury mechanism resulting in excessive torsion of the knee.  Alpine skiing is a sport that requires good strength and control at the knees, and unfortunately it happens quite regularly that a bad fall leads to damage to the anterior cruciate ligament. For example, when the ski does not detach from the boot as it should during a fall.


What does it look like?  

Injuries to the anterior cruciate ligament therefore lead to a decrease in passive stability of the knee and a decrease in proprioception. This type of injury occurs frequently following a torsional fall.

There are different grades of ligament injury (or sprain) that vary depending on the severity of the ligament injury.

  • A grade 1 tear represents an elongation of the ligamentous fibers without frank tear. It is possible to have a little tenderness and swelling. The knee does not necessarily feel unstable or gives a feeling that it wants to “let go”.
    A grade 2 tear corresponds to a partial tear of the ligament. It is possible to have small bleeding, some tenderness and moderate swelling with some loss of function. The knee may appear unstable or loose during activity.
  • A grade 3 tear is a complete tear. There is bleeding, tenderness, and some or much swelling. The ligament cannot control the movements of the knee which seems unstable or loose at times.


How can physiotherapy help?

Grade 1 and 2 cases are almost always managed with conservative (non-surgical) treatments, such as physiotherapy, and surgery is rarely an option if the involvement is limited to the anterior cruciate ligament. For grade 3 cases (complete tear), conservative treatments often allow an excellent recovery of function and even the return to several sports. In these cases, physiotherapy treatments are more than desirable in order to re-educate the strength and active control of the knee.

It happens that in some cases, despite optimal rehabilitation after a complete tear, significant instability persists with unpredictable evasions of the knee. In this case, surgery often becomes the option to consider. It is known, however, that the better the knee has recovered before surgery, the easier it will be for rehabilitation after surgery. It is therefore essential after a tear of the anterior crusader to properly re-educate the mobility, strength and control of the knee, whether surgery is considered or not.

Current scientific evidence shows us that conservative treatments, therefore without surgery, remain the treatments of choice for complete anterior cruciate ligament tears.  Injury prevention, strengthening, balance and proprioception exercises are strongly encouraged both during the pre-season period and during the sports season.


To learn more, do not hesitate to consult your physiotherapist!