Introduction
The posterior cruciate ligament rupture as an injury to the posterior cruciate ligament of the knee is already partially noticeable at the time of the rupture. The affected person feels symptoms, in this case the rupture in the knee joint, possibly a sound (cracking) can also be heard when the rupture occurs. This is followed by swelling and pain in the area of the knee joint.
The swelling in a posterior cruciate ligament rupture is the result of a bloody joint effusion caused by the rupture of blood vessels supplying the knee joint. This leads to bleeding into the joint space, resulting in the effusion. This bloody joint effusion is called haemarthros (arthron = joint, haem = blood).
The symptoms/pains of the knee affected by the torn posterior cruciate ligament are caused by the stretching of the joint capsule, which is the result of the knee joint effusion. The irritation of nearby nerves mediates the sensation of pain in case of a torn posterior cruciate ligament. A further consequence of the posterior cruciate ligament rupture, including effusion, is the restriction of the knee’s mobility.
An additional symptom of a torn posterior cruciate ligament is increased instability of the affected leg. The posterior cruciate ligament acts as a stabilizer of the knee joint, especially in knee flexion. It prevents the rear sliding of the lower leg in relation to the thigh. In the event of a torn posterior cruciate ligament, this stabilization is consequently eliminated, so that instability occurs as a typical symptom in the event of a torn posterior cruciate ligament.
How is the posterior cruciate ligament rupture determined?
During the physical examination typical signs of a posterior cruciate ligament rupture can be triggered. These include positive results in the rear drawer test as well as in the Lachmann test. For these test procedures, the examiner bends the injured leg of the person concerned in the knee by 90 degrees in the drawer test and by 30 degrees in the Lachmann test.
The next step is to move the lower leg back towards the thigh. In the case of a torn posterior cruciate ligament, a positive result with shifting backwards occurs, but if the knee is not injured, no movement backwards can be triggered. Very often a torn posterior cruciate ligament is accompanied by other symptoms and injuries on the knee on the affected side of the body.
There is often a combination with damage to the collateral ligaments (collateral ligaments, medial ligamentum collaterale and lateral ligamentum collaterale) of the knee joint. Bony tearing injuries of the posterior cruciate ligament at its anchorage point on the shin bone (tibia) are also possible concomitant injuries in the event of a posterior cruciate ligament tear. If a posterior cruciate ligament rupture is not treated, for example because the patient does not notice the rupture due to the absence of or very mild symptoms, the symptom of instability comes to the fore and a chronic loss of stability develops.
Patients complain of symptoms such as giving way or slipping of the injured knee, which is known as the “give way” symptom. In addition to the instability described above, wear and tear of the joint, especially of the cartilage and the menisci, develops over time in the event of a posterior cruciate ligament rupture without treatment. A posterior capsular contracture is particularly typical.
Since the torn posterior cruciate ligament regularly causes the lower leg to sink backwards, the joint capsule adapts to this movement by shortening, so that so-called contracture (shortening) occurs. Arthrosis is another typical sign of wear and tear that is typical of a torn posterior cruciate ligament that has not been treated. On the one hand, these occur at the knee joint itself as knee joint arthrosis or gonarthrosis.
On the other hand, after a posterior cruciate ligament rupture, a so-called retro-patellar arthrosis (retro = behind, patella = kneecap) can develop. This refers to wear and tear of the joint space between the rear patella and the thigh bone (humerus). Such arthroses become noticeable as pain. Retropatellar arthrosis as a result of a torn posterior cruciate ligament is characterized by pain, which occurs mainly when walking downhill or down stairs. Even after sitting down and getting up from this position, the patient feels increased pain, which is located retropatellarly, i.e. behind the kneecap.
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