The knee is a complex joint at the intersection between the leg and the thigh comprising the ends of the femur and tibia, and the patella. This weight-bearing joint is always under strain as it supports the weight of the body and enables movement. The primary motion of the knee is flexion / extension, but it also has the ability to rotate. To function correctly and absorb the strain it is put under, it has a powerful stabilizing mechanism in which the ligaments play a dominating role.
Ligaments are very resistant, extendable bands of fibrous tissue composed mainly of collagen. Their role is to join the bones together and maintain contact between the joint surfaces during movement. They confer the joint mobility as well as stability by restricting certain movements.
Four ligaments stabilize the knee: the lateral internal and external ligaments, which ensure lateral stability by preventing forced varus or valgus movements (excessive movement inwards or outwards), and the anterior and posterior cruciate ligaments located in the joint cavity, which are part of the central pivot. The posterior cruciate ligament (PCL) prevents “posterior drawer” movements of the tibia, or displacement of the tibia backwards in relation to the femur, and the anterior cruciate ligament (ACL) prevents excessive rotational movements.
Mechanism and causes of anterior cruciate ligament damage
Any abnormal or excessive movement of the knee can result in ligament damage.
Anterior cruciate ligament damage usually occurs following:
- changes in direction inducing excessive rotational movements of the body inwards or outwards in relation to the foot,
- twisting of the knee when landing badly after a jump,
- hyperextension or hyperflexion of the joint.
These situations are likely to stretch the ligament and could result in rupture.
Rupture of the anterior cruciate ligament is generally linked to sports injuries. It is notably characteristic of “pivoting” sports such as team sports (football, rugby, handball, basketball), fighting sports, tennis or skiing, which require brutal changes in direction, deceleration and stopping. Various factors such as the state of the pitch, the level of fitness or wearing shoes that are unsuitable for the activity in question can exacerbate the risk.
Some hormonal, anatomical, genetic, metabolic or neuromuscular factors can also be implicated in the occurrence of this type of trauma.
However, this damage is rarely associated with accidents occurring in daily life.
Symptoms of ACLR
- Pain: it can be sharp and immediate;
- A cracking sound may be heard and a dislocation can be felt at the time of the injury;
- Edema (swelling) on the knee due to effusion, which does not necessarily develop immediately;
- Hemarthrosis (bleeding linked to the rupture of blood vessels in the ligament in the joint cavity);
- Functional problems: instability and sometimes the inability to completely straighten the leg.
The diagnosis is primarily clinical and must be diagnosed by an orthopedic surgeon where possible.
An MRI can also be performed, but cannot replace a clinical examination. Ligaments are not visible on x-rays, so this examination is of no interest for ligament damage alone. However, it can be carried out if there is a suspected concomitant fracture or luxation.
Arthroscopy can be useful when the clinical examination and the MRI do not provide a clear diagnosis and is often carried out just before the surgical procedure.
As the anterior cruciate ligament does not maintain knee stability alone, it is possible to live without it and therefore not undergo surgery.
However, this conservative method is only suitable for relatively sedentary subjects who do not partake in intensive sports activities, or the elderly.
Firstly, the knee is immobilized with a brace to give the damaged ligament time to heal and the bruise to disappear. Cryotherapy (application of extreme cold) is also used, in particular to reduce the edema. Initially, ice can be put on the knee 6 times a day on average then less frequently for as long as the edema and pain persist.
Then, physiotherapy will help offset the instability with exercises to reinforce the muscles that help stabilize the knee (hamstring and quadriceps) and to improve overall proprioception.
Many patients recover satisfactory knee stability, adequate for performing everyday activities and some sports such as swimming, cycling or even running. However, if the instability or pain persists, it is necessary to consult an orthopedic surgeon who will review case by case the advantages of a surgical procedure with the aim of preventing the onset of osteoarthritis and restoring better knee stability.
It is systematic for anyone requiring optimum knee stability (elite athletes, some amateurs who wish to resume a sports activity (football, skiing…), some professionals).
Indeed, some activities are impossible with a history of unoperated anterior cruciate ligament rupture without running the risk of inducing other traumas or the progressive development of osteoarthritis.
The procedure is performed arthroscopically and consists in grafting a tendon to replace the ruptured ligament (knee ligament reconstruction)
Although it carries the classic risks associated with any operation, it is minimally invasive, extremely successful and provides a permanent treatment whilst preventing damage linked to osteoarthritis