Cruciate ligament rupture - rear

A tear of the posterior cruciate ligament occurs primarily in car accidents. Because the posterior cruciate ligament is one of the strongest ligament structures in the knee joint, a posterior cruciate ligament tear is a very rare injury - tears of the anterior cruciate ligament or the medial collateral ligament are far more common.

The anterior and posterior cruciate ligaments run crosswise from the cruciate ligament bumps of the shinbone (tibia) to the thigh (femur). The ligaments fix the knee joint, with the anterior cruciate ligament performing the more important stabilizing function. The anterior cruciate ligament limits knee extension, while the posterior cruciate ligament prevents straight backward displacement at the tibial plateau.

A tear of the posterior cruciate ligament is usually caused by external force, for example in sports or traffic accidents. In a bent knee position (such as when sitting in a car), the posterior cruciate ligament is strongly stretched. If the ligament is severely overstretched by an external force, the posterior cruciate ligament can tear.

In contrast to the anterior cruciate ligament tear, only the posterior cruciate ligament is rarely injured - in most cases, other ligaments and the joint capsule are also injured.

When the posterior cruciate ligament tears, many sufferers hear or feel a crack in the knee joint. This is followed by swelling of the knee and severe pain. The occurrence of a joint effusion can also be possible.

These symptoms subside after some time, but the knee no longer has the original degree of stability due to the torn cruciate ligament. A tear of the posterior cruciate ligament causes the tibial plateau to shift backwards in relation to the thigh. Affected individuals notice this especially when walking down stairs and compensate for the joint instability by always walking with their knees slightly bent.

Over time, the lack of knee stability can damage other structures such as the articular cartilage or the joint capsule and lead to arthrosis (joint wear).

The description of the accident and the characteristic knee swelling alone can often indicate that a cruciate ligament tear has probably occurred before further examinations. The doctor then subjects the knee joint to a stability test - the torn posterior cruciate ligament makes it possible for the tibia to move backwards in relation to the thigh. However, it may not be possible to perform the stability test until several days after the accident due to the severe swelling and pain.

A tear of the posterior cruciate ligament is diagnosed by magnetic resonance imaging (MRI). This imaging technique makes the cruciate ligaments and the damaged structures clearly visible. With the help of X-rays taken from two different directions, damage to the bony structures can be detected.

Whether or not a surgical restoration of the posterior cruciate ligament should be performed depends on the individual situation as well as the personal demands of the patient. There is no standard whether surgery should be performed or not. However, if the posterior cruciate ligament is torn out together with a piece of bone or if additional injuries are present, surgery should be performed.

Today's standard surgical procedure is arthroscopically assisted cruciate ligament reconstruction. In this procedure, part of the patella tendon, for example, which lies between the kneecap and the tibia, is removed as a replacement for the original posterior 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. However, the surgical and long-term results of a cruciate ligament reconstruction are not as successful with the posterior cruciate ligament as with the replacement of the anterior cruciate ligament.

In many cases, the symptoms of a torn posterior cruciate ligament can be alleviated without surgery by wearing special splints. These splints must also be worn during the period after surgery in order to protect the newly inserted ligament. Physiotherapy (physical therapy) is an important supplement to prevent later knee complaints.

Only in rare cases do complications occur after the operation, such as bleeding, thrombosis, infection of the joint or nerve injury. Since the tendon graft consists of the body's own tissue, it is usually tolerated without problems and the surgical wounds heal well.

Only very rarely does damage to the meniscus, a fracture of the kneecap or detachment of the tendon graft occur. Permanent instability of the knee joint also occurs very rarely.

12 to 16 weeks after the operation, the patient can usually do sports again without any restrictions, but it should be noted that the knee no longer has the original stability due to the cruciate ligament graft. Premature arthrosis (wear and tear of the joint) can be prevented by consistent training and physiotherapy.