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What is the cruciate ligament?

The cruciate ligament is the central pillar of stability of the knee joint. Technically speaking, it is particularly resistant connective tissue. And while tendons in our body always connect a muscle to a bone, ligaments connect bones directly. We distinguish between an anterior and a posterior cruciate ligament. Inside the knee, the two ligaments cross each other and from this special arrangement against each other they also get their name – precisely the cruciate ligaments.

Mann, der sich an sein schmerzendes Knie fasst

What are the functions of the cruciate ligaments?

The task of the anterior cruciate ligament is to prevent the thigh from shifting forward relative to the lower leg. The rear provides stability in the opposite direction. If one of these ligaments tears, this causes the knee to give way or “let out”. The injured person then has the feeling as if the knee is no longer stable and actively controllable, but as if it were simply tipping away. Small consolation, but still: this is not the case, but it is the displacement of the upper leg against the lower leg – in the language of the medical profession, the “Giving Way Attack”.

In addition to their function as stabilizers in the knee joint, the cruciate ligaments have a second important task. The task is that they guide the movement mechanism of the knee joint – the so-called roll-slide mechanism, which makes it possible for us to bend our knees up to 160 degrees in the first place. When one of the cruciate ligaments is torn, other structures within the knee – the meniscus and cartilage – are subjected to greater stress and thus become more worn over time. This wear is then called secondary damage.

What happens when too much stress is placed on the cruciate ligaments?

Cruciate ligaments are enormously resistant and constantly stressed. However, what is too much is too much: Especially if the cruciate ligament is stretched strongly at the same time – i.e. if the knee is bent too much – and the knee is twisted at the same time, one of the ligaments can tear – in the case of extreme loads, both equally. In individual cases, it is possible to get through everyday life well even with a torn cruciate ligament. This usually depends on the type of loads and the muscle corset in the knee joint. In very many cases, however, surgical intervention is necessary. Should surgery become necessary, there are several options for surgery – depending on the type of cruciate ligament injury.

The most common injury is a tear of the anterior cruciate ligament – the posterior one tears much less frequently. And it’s about a 9:1 ratio. Interestingly, the chance of recovery without surgery is significantly more likely with a rupture of the posterior cruciate ligament than with the anterior. Whether surgical treatment of the cruciate ligament is necessary is influenced by several factors: the absolute age as well as the biological age, the patient’s sporting ability and the type of cruciate ligament tear.

In the case of an avulsion at the bony attachment or a bony avulsion, there is a chance that the patient ‘s own cruciate ligament can be restored. Deciding whether this treatment method is indicated is tricky – an experienced orthopedic surgeon is the right person to contact. If the ligament is not only torn at the base but also destroyed in itself, only a replacement with suitable tendon material has a chance of success.

The range of interventions is now wide:

Restoration of the own cruciate ligament

If the cruciate ligament tears out near its attachment to the bone or together with a piece of bone, and without serious injury to the ligament itself, it can be reconstructed surgically. A full recovery is possible.

Augmentation of the cruciate ligament

It often happens that either the anterior straight or the posterior oblique part of the cruciate ligament tears and the other part holds. In this case, it is possible to strengthen the received part.

Cruciate ligament replacement with endogenous tendon

If the cruciate ligament is completely destroyed, the method of choice is complete replacement with the patient’s owntendons (semitendinosus, quadriceps or patellar tendon).

Singlebundle vs. Doublebundle

Normally, anatomical restoration using the single-bundle technique is effective. Here, not two tapes but one stronger one is used. In exceptional cases, both the anterior straight and posterior oblique cruciate ligaments are replaced – especially in patients with extreme athletic ambitions.

Transplantation of the cruciate ligament

Guidelines for the use of donor tissue have improved in recent years to the benefit of patients. As a result, transplantation is becoming increasingly popular. The advantage of this is that the procedure is much gentler, as there is no need to remove the body’s own vision. Rejection reactions are not to be feared and the stability achieved is as good or better than with autologous tissue.

Operation of the posterior cruciate ligament

Corresponding to the likelihood of tearing the posterior cruciate ligament, repair is a much less common operation. It requires enormous skill and knowledge. Like the anterior cruciate ligament, the posterior cruciate ligament can be replaced and restored with the body’s own vision.

Peripheral instabilities

In addition to the known structures within the knee joint, there are a number of other ligaments that provide additional stability. Injuries to these ligaments are also easily missed by physicians on MRI and then not appropriately incorporated into the overall surgical plan.

Tissue Ingeneering

In the course of biological regeneration, the inserted ligament is fully reintegrated into the joint by the ingrowth of new blood vessels and the sprouting of local connective tissue cells. How can we support our body in this? Essentially, there are two possibilities: First, by injecting blood plasma – autologous conditioned plasma, or second, by introducing stem cells, which can be obtained from bone marrow or adipose tissue.

What are the chances of success of cruciate ligament surgery?

The success of cruciate ligament surgery depends on several factors during the course of treatment. The first thing that counts is a rapid and expert diagnosis. An experienced orthopedic surgeon through imaging diagnostics – So MRI and X-rays accurately, identifies the type and degree of severity of injury to the ligaments and recommends the optimal treatment. The next step is the professionally planned and performed surgical procedure. At this point, the sole responsibility of the treating physician ends and the patient is required to contribute. After all, after a well-done operation, everything depends on the will and consistency of the patient. A professionally operated cruciate ligament can regain full weight-bearing capacity, but only if rehabilitation is neither interrupted nor stopped early. About 80% of patients reach their pre-injury athletic level under these conditions.

What should be considered after cruciate ligament surgery?

Surgery is the first and certainly the most important step in restoring full mobility and resilience. However, consistent follow-up care is equally important to keep the rehabilitation phase as short as possible and to optimize the final result.

What all belongs to this phase of “back to normal”? It starts with postoperative care with a knee brace as well as further relief of the healing joint with crutches. This relief phase accelerates the re-growth of the ligaments. This is supplemented by intensive physiotherapy immediately after the operation. In addition to treatments by the physiotherapist, these include underwater gymnastics and training on the underwater treadmill and, subsequently, appropriate strength and coordination training.

How long does recovery take after cruciate ligament surgery?

Primary wound healing takes about six weeks. Complete biological regeneration is completed after a good year, provided that the procedure is appropriately consistent. In this context, continuous work in rehabilitation is particularly important. It should be mentioned here once again that the consistent work on regaining strength, coordination and thus movement security are the most important. And: Miracle cures within a few weeks are promised here or there, but they do not happen and those who want too much too soon often end up back on field 1 – the operating table.

When is sport possible again after cruciate ligament surgery?

As an approximate timetable, ergometer training – training on the indoor bike – should be possible after six weeks. Here, the load can be optimally adjusted and the additional load caused by the user’s own body weight or even force effects to the side are avoided. After 12 weeks, light running can usually be started. However, this is only ever done in conjunction with all the essential strength and coordination exercises. Ambitious hobby or even competitive sports, especially contact and ball sports, are possible with low risk after 12 months – the training should be designed in close coordination with the treating physician.