The function of the knee is to enable mobility, but also to hold the body's weight and to transfer it to the feet during walking. The joint facets of the femur are convex, while the tibia's are mostly flat.
This way, the mobility of the knee is enhanced, but so is stability reduced. To improve the stability of the knee and make the transferred weight to the tibia as little as possible, it is necessary for the joint facets to be bigger and complement each other. This is why there is a strong emphasis on the function of the stabilizers of the knee joint. We divide the knee stabilizers into active and passive. Active stabilizers are muscles which move the joint. Passive stabilizers are ligaments, joint surface and menisci. The most important ligaments of the knee are the anterior and posterior cruciate ligament, as well as the medial and lateral collateral ligament. The anterior and posterior cruciate ligament sin the knee form a X-shape structure. This is where they get their name form. Cruciate ligament injuries, and especially the interior cruciate ligament, are very common, especially in people who actively train football, basketball or ski (around 30 people per 100 000 yearly). The role of the anterior cruciate ligament is primarily to stop excessive movements of the tibia to the front in comparison to the thigh. It is also very important for stopping excessive rotation of the thigh.
The stability and mobility of the knee is affected because of injury to the anterior cruciate ligament. Acute injuries of the anterior cruciate ligament are commonly a result of excessive rotation or hyperextension of the knee. The injured person usually describes the symptoms as hearing that something broke in the knee and that the knee „escaped“ from position. After that, pain and swelling occur. Usually other structures in the knee are affected along with the anterior cruciate ligament injury. After injury, the knee becomes unstable, hurts and prevents training or physical activity. The diagnosis is made on the basis of understanding the biomechanical elements of the injury and detailed description of symptoms and injury mechanism.
Especially important are the facts about the strength and direction of the force which affected the knee in the moment of injury, hearing that something broke in the knee, not being able to continue activity and fast swelling of the knee. Clinical examination includes test to assess knee stability. To confirm the diagnosis in doubtful cases, magnetic resonance of the knee is done. Magnetic resonance (MR) ia s non-invasive procedure to get quality data about the structures of the knee. After determining the type and size of injury, a decision is made on treatment. It is important to emphasize that the anterior cruciate ligament cannot heal itself. Treatment must be personalized to every patient. The dialogue between the physician and patient is very important. Most important factors that determine the decision are patient age, motivation, degree and type of physical activity that the person is willing to do, degree of knee instability and the state of other knee structures. The treatment can be surgical and conservative.
Conservative, i.e. non-surgical treatment is composed of strengthening the musculature and improving proprioception (sensation of the location in the surroundings) of the knee. This way, we are trying to compensate the absence of an important passive stabilizer such as the anterior cruciate ligament with muscles. It is important to emphasize that by strengthening the musculature that affect the knee joint, we cannot achieve rotational stability of the knee which the cruciate ligaments do.
Patients with the loss of the anterior cruciate ligament can develop degenerative changes of the joint quicker and are more prone to repeated knee injuries. Because of that reason, in younger and motivated patients, and especially professional and recreative athletes, we advise a surgical procedure. The surgery consists of reconstructing the anterior cruciate ligament. Research from the early 90s, pointed that it is important to delay the surgery of the anterior cruciate ligament for a few weeks after injury because of the fear that the mobility of the knee will be lost.
Because of that, first arthroscopy and knee lavage were done, and only a few weeks later reconstruction of the anterior cruciate ligament. With the development of precise diagnostics (MR of the knee), surgical techniques and post operational rehabilitation, it is more common thought that reconstruction of the anterior cruciate ligament does not have to be delayed or made in so-called two phases. This way, two surgeries are avoided, as well as the loss of time in waiting for the second surgery and potential additional injuries because of knee instability during the waiting time. The surgical technique has significantly changed in the past twenty years.
The whole surgery is done arthroscopically where the knee is not opened up, but the surgery can be done via two or three small cuts of a few millimeters. The course of the surgery is visualized on a display and if the patient wants to, he or she can look at the surgery and communicate with the surgeon. A graft from the patient is used for reconstruction. The graft is most commonly a part of the tendon of the muscles of the back part of the thigh or the central part of the patellar ligament from the same knee. Such a graft can be completely fixed with resorptive material which „melts“ in the body after the graft if placed properly. For complete ingrowth of the graft, it takes a few weeks and putting bigger loads on the knee is forbidden. Correct postoperative rehabilitation is complex and extremely important for full recovery and lasts 5 to 6 months after the surgery.