Cruciate ligament rupture

Cruciate ligament rupture: what’s that?

In order to enable the knee joint to carry out its natural rolling and sliding movement, it is stabilised and guided by various ligaments in addition to its muscles.
Here, the most important are:

• The anterior cruciate ligament (ACL)
• The posterior cruciate ligament (PCL)
• Collateral ligaments (medial cruciate ligament - MCL and lateral collateral ligament - LCL)

The central knee joint stabiliser is the anterior cruciate ligament, which is why a tear (rupture) may result in impaired performance - depending on the structural status of the knee-guiding musculature. The articular surface in the knee bend is then no longer correctly burdened, which may result in further damages to the knee such as joint cartilage or the menisci injuries. With 90-95% of all cases, the anterior cruciate ligament rupture is also the most common of cruciate ligament injuries.

Here, the cruciate ligaments can be fully ruptured or only torn in-part (partial rupture). Some 35,000 ruptures of the anterior cruciate ligament are registered in Germany per year, most frequently in the age group of the 15 to 30-year-olds. Moreover, females incur an injury rate which is up to 8 times higher than in males.

Causes of a cruciate ligament rupture

Normally, a cruciate ligament rupture results from a sports accident, frequently due to unexpected, abrupt changes in direction with a bent knee, with the effect of high acceleration forces such as when skiing, playing tennis, squash, basketball, handball or soccer.

Here, an outward rotation of the lower leg takes place under heavily acting forces with simultaneous opening of the knee joint on its inner side. The cruciate ligament can then no longer bear this so-called valgus stress.

Symptoms of a cruciate ligament rupture

The most frequent acute symptoms of an injury to the cruciate ligament are pain, restricted movement and the formation of haematoma (haemarthrosis). The latter can also cause severe pain and feelings of tension.

An instability of the knee joint normally only sets in after the acute injury symptoms have abated. This instability may lead to insecurity when going upstairs, walking downhill and running (if still possible).
The further procedure depends on the extent of the injury. Here, it is important not to observe the cruciate ligament injury standalone, but also to take accompanying injuries to cartilage, bones, menisci and further ligaments into account.

Stages of a cruciate ligament rupture

The so-called “drawer test” is most frequently applied for the quantification of the stage of a cruciate ligament rupture. When the anterior cruciate ligament is damaged, it establishes hypermobility of the lower leg vis-à-vis the thigh at the front and, in case of damage of the posterior cruciate ligament, at the rear. The precise stability measurement of the knee joint is made using measurement devices (KT-1000, rolimeter, KLT) which are placed on the joint or the bone contours. These instruments are used to record the hypermobility under stress in millimetres.

An X-ray where the knee joint is clamped under load and the angle of so-called expandability is measured in degrees provides a further option to establish the degree of instability. However, no clear classification of the instability stages exists.

Diagnosis of a cruciate ligament rupture

The diagnosis of a ligament injury in the knee joint is based on clinical case history as well as imaging procedures such as X-ray images and MRI.

Normally, a clinical examination using various standardised examination procedures is only possible after the knee swelling has declined. Here, the hypermobility of the knee joint (refer to the stages of a cruciate ligament rupture) is estimated using tests such as the Lachman test, the pivot shift test or the drawer test. Quantifying measurement procedures have already been described under the section “Stages of a cruciate ligament rupture”.

How can a cruciate ligament rupture be prevented?

Prevention of a cruciate ligament injury is in principle based on the respective form of sports. Therefore, the specific requirements of the sports, e.g. when skiing or playing soccer must be taken into account with reference to the movement patterns and be purposefully trained via strength and coordination training. Moreover, the individual physical abilities should be attuned to the risk profile. Thus, for example, it makes no sense to play soccer with an increased BMI without preventive training because injuries would be pre-programmed here in corresponding risk situations. Certain knee exercises  – as can also be found on the BORT website – can prove to be a sensible preventive measure.

What therapy options are available for a cruciate ligament rupture?

For acute treatment, elevation of the leg, cooling the knee and, if applicable, cannulation with drainage of the haemarthrosis may be suitable. Normally, freshly injured patients cannot be examined more closely due to the complaints described. During this phase, examinations such as the drawer test or a clamped X-ray make no sense because the results would be falsified due to the pain-caused counter-tension. As first care, the patient should be provided with crutches and a knee brace and be subjected to further diagnosis with follow-up therapy after the acute symptoms have abated.

For patients who wish to continue to achieve their full accomplishments during their leisure time and in sports, operative replacement of the ligament is the first-line therapy for a rupture of the anterior cruciate ligament. Standardised transplantation procedures are used successfully for cruciate ligament surgery (ligament replacement: semitendinosus tendon, ligamentum patellae, quadriceps tendon). Within the scope of the operation, it goes without saying that possible accompanying injuries to the menisci or lateral collateral ligament are also taken into account. Following a cruciate ligament operation, it makes sense to support the transition to full burdening with a knee brace . It takes some 6 weeks until the replacement ligament has waxed. During this initial healing phase, remedial gymnastics in the form of movement exercises, soft tissue techniques (massages, lymphatic drainage, etc.) and gait training can be carried out. After the 6-week healing phase, a rehabilitation phase of a further 2-4 months commences. Here, too, the body’s abilities must be trained so appropriately that the sports-specific requirements can be compensated. Because the cruciate ligament replacement has no nerve cells, it does not pass on information regarding joint mobility to the brain ideally. Therefore, every cruciate ligament patient should carry out daily preventive exercise in order to enable adequate functioning of the replacement ligament. Depending on the form of sports, full burdening is usually only possible after 6 months. An undisciplined rehabilitation phase jeopardises the point in time of return to “normality” and the quality of the result of the operation.
The final alteration to the permanent crucial ligament “scar” takes up to one year. During this period, it makes sense to use a corresponding stabilising brace for risk burdens.