Cruciate ligament rupture - front

The anterior cruciate ligament is often torn in sports accidents, for example when skiing or playing football. It is the most common ligament injury to the knee, closely followed by injury to the medial collateral ligament. The posterior cruciate ligament, on the other hand, is rarely affected by injury.

The cruciate ligaments are arranged in a cross shape and run from the cruciate ligament bumps of the tibia to the femur. The anterior and posterior cruciate ligaments stabilize the knee joint during movement, with the anterior cruciate ligament performing the more important stabilizing function. The following three ligament parts of the anterior cruciate ligament can be distinguished:

• anterior-inner (anteromedial) portion: this part of the ligament is strongly strained during knee flexion and has the highest risk of tearing in case of injury.
• intermediate (intermediary) portion
• Posterior-external (posterolateral) portion: This is the portion that becomes most tense during knee extension.

A tear of the anterior cruciate ligament is usually the result of an abrupt braking movement, during which the tendons are stretched at the same time. This situation occurs, for example, during a fall, as the knee is involuntarily braked, stretched and rotated outwards. So-called complex injuries often occur. This means that not only the cruciate ligament itself, but also the medial meniscus, the medial collateral ligament or both are additionally damaged. If all three structures are affected, this is called an "unhappy triad".

The risk of an anterior cruciate ligament rupture can be significantly reduced by warming up before sports activities, jump training, running training as well as defensive behaviour during sports.

If the anterior cruciate ligament tears, this usually causes severe pain that subsides after a short time. However, the pain can recur with renewed exertion.

In addition to the ligaments, small blood vessels also tear, causing bruising and swelling of the knee joint. These symptoms subside after some time. Due to the torn cruciate ligament, the knee no longer has the full extent of stability, which is why the lower leg shifts slightly forward in relation to the upper leg, especially when walking down stairs. For those affected, it gives the impression that the knee is "wobbling".

In some cases, a rupture of the anterior cruciate ligament cannot be detected immediately because the thigh muscles tighten strongly as a reflex to the pain stimulus, which temporarily strengthens the knee and therefore the instability is not noticed.

By describing the course of the accident and the characteristic strong swelling of the knee joint, the presence of a torn cruciate ligament can often already be concluded before further examinations. In addition, the doctor subjects the knee joint to a stability test (the torn cruciate ligament makes it possible for the upper and lower leg to shift). However, this examination can sometimes only be carried out a few days after the accident due to the severe swelling and the painful knee joint. The doctor also assesses the patient's gait pattern - resting while walking indicates a cruciate ligament tear.

X-rays taken from two directions can clarify whether the accident also resulted in bone fractures or bony avulsion of the ligament. Magnetic resonance imaging (MRI) is used to determine the exact location of the cruciate ligament tear and to clarify injuries to the meniscus. Arthroscopy (joint endoscopy) for the diagnosis of a cruciate ligament tear is no longer common today.

Surgery brings the best long-term results, but this should be weighed against the risks of surgery. Especially for people who are not very active in sports, a good stability of the knee joint can be achieved despite an anterior cruciate ligament rupture through consistent training of the thigh muscles. If the stability gained is sufficient for everyday stress, which is usually the case, an operation is not absolutely necessary for these people.

In active people and especially in athletes, the anterior cruciate ligament is surgically replaced to regain full stability of the knee joint.

The current standard procedure is arthroscopically assisted cruciate ligament reconstruction. In this procedure, the patella tendon, for example, which lies between the kneecap and the tibia, is taken as a replacement for the original anterior cruciate ligament. This tendon is the right length and can be surgically removed so that there is a small piece of bone at both ends of the tendon. During arthroscopy (joint endoscopy), the patella tendon is placed in the same position as the original cruciate ligament tendon. The pieces of bone are fixed in the tibia bone and in the femur bone by screws or press-fitting.

Other tendon grafts are more suitable than patellar tendon replacement, especially for patients who have to perform frequent kneeling activities. For example, tendon parts of the thigh muscles - such as the gracilis tendon or the semitendinosus tendon - can be used.

For new methods, in which the healing of the cruciate ligament is to be supported with the help of the body's own stem cells of the bone marrow, there is currently still a lack of empirical values regarding the benefits and risks of these therapies.

In the period after the operation, the knee must be rested, as the replaced anterior cruciate ligament may not yet be fully loaded. Cooling with ice and physiotherapy support the healing process. Lymphatic drainage can be helpful if the knee is swollen. Initially, a special knee brace should be worn to stabilize the joint. In order to fully restore the function of the knee joint, it is particularly important to train the knee with a careful, restorative load as well as through physiotherapy.

Rarely, complications such as bleeding, thrombosis, joint infections or nerve injuries can occur after anterior cruciate ligament rupture surgery. The autologous tendon graft is usually very well tolerated and the surgical wounds heal quickly. In very rare cases, the graft can also rupture. Special risks of a cruciate ligament rupture operation such as increasing instability, damage to the meniscus or detachment of the graft also occur only very rarely.

The long-term results of the surgical procedure are very good. After several weeks, the ability to do sports is restored - good results can be achieved especially by an early start of physiotherapy and sports that are gentle on the knee, such as backstroke. The knee load should only be increased slowly and gradually after consultation with the treating physician.

After a long period of rehabilitation, sports that put a strain on the knee, such as skiing or football, may be possible again, but it should be noted that the knee often no longer has the original stability, even in spite of a cruciate ligament transplant. Premature arthrosis (wear and tear of the joint) can be delayed by consistent muscle training.