A posterior cruciate ligament rupture is caused by exceeding the maximum possible extension of the posterior cruciate ligament, usually by an external force.
This is a complete rupture, a so-called continuity interruption, of the posterior cruciate ligament, whereby a sagittal (= parallel to the central axis) instability and the so-called drawer phenomenon (= large displacement of the lower leg against the thigh) becomes noticeable.
Causes for cruciate ligament ruptures
In most cases, not only the posterior cruciate ligament is affected by a posterior cruciate ligament rupture. The injuries are usually far more complex and usually affect the entire knee joint, sometimes with enormous adverse effects.
Often, accidents are responsible for torn posterior cruciate ligaments, and often also car accidents. This is due to the fact that the lower leg is bent when sitting in a car. If you push it forcibly against it, the rear cruciate ligament tears.
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A tear of the posterior cruciate ligament is usually accompanied by typical symptoms that are characteristic of the injury.
Immediately after the trauma responsible for the rupture of the posterior cruciate ligament, there is usually swelling of the knee and considerable pain in the knee joint. In addition, an instability of the affected knee joint is noticeable, which consists especially in the flexion of the knee joint.
Depending on the extent of the injury and the soft tissue structures affected, bruising and open wounds can occur. Often there are concomitant injuries to other ligaments, bones or cartilage, which is why the resulting pain can only be localized diffusely.
During the physical examination, the so-called drawer phenomenon is conspicuous, as the knee joint lacks an important fixation due to the tear.
A positive drawer test and a Lachmann test are typical signs of a posterior cruciate ligament rupture.
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Drawer test for posterior cruciate ligament rupture
The drawer test is used for the clinical diagnosis of posterior cruciate ligament rupture.
In general, examinations of a knee joint with a fresh ligament injury are difficult due to the severe pain. The pain occurs at the moment of injury, diminishes, but usually returns when the ligament is loaded.
A comparison should always be made with the “healthy” side. The rupture can cause severe swelling and effusions. During the examination, the degree of possible mobility and the meniscus signs must be clarified. As already mentioned, the medial and lateral ligament stability can be checked by means of the so-called Lachmann test. The drawer test, which is also described, cannot be triggered in the case of an acute injury due to the muscular counter-tension in the acute case.
In the case of acute swelling of the knee joint and a knee joint puncture indicated, as a result, it can also provide information as to whether or not there is a ligament injury in the knee joint. If blood from the knee joint is punctured during a puncture, this usually indicates a ligament injury to the knee joint
Cruciate ligament ruptures are not always diagnosed in acute cases. Frequently, the diagnosis is only made after a noticeable instability of the knee joint. This can lead to changes in the cartilage and meniscus due to wear and tear.
The diagnosis is made primarily by testing the stability of the knee joint in the extended and flexed positions, in external and internal rotation and in the normal position of the foot. A close examination of the knee with regard to swelling, effusion and the gait pattern must of course also be carried out.
The adjacent joints should always be examined for clarification and the blood circulation, motor function and sensitivity should be taken into account. In the case of acute injuries, stability tests are generally difficult to carry out due to muscle tension, so that further apparatus measures must be taken to make a diagnosis. These are for example:
- X-ray diagnostics: X-ray images in various variations provide information about possible bony lesions.
- Magnetic resonance tomography (MRT): For final clarification whether and to what extent a cruciate ligament rupture is present. With the help of magnetic resonance imaging (MRI), the damage that has occurred can be accurately assessed and any necessary operations can be planned and initiated precisely.
A puncture can also provide information about a torn cruciate ligament. As soon as blood is punctured during such an operation, a ligament injury in the knee joint can be assumed.
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Anatomy cruciate ligament
The knee joint is the largest joint in the human body. The knee joint includes the femur, tibia, patella, meniscus, various capsule tissues, the ligamentous apparatus and many bursae.
If we now take a closer look at the ligamentous apparatus, we must distinguish between the collateral ligaments, the internal ligaments and the cruciate ligaments, among others. The cruciate ligaments run from the middle of the head of the shinbone to the thigh bone and cross each other in the process. The task of the cruciate ligaments is to stabilize the knee by preventing the lower leg from sliding forward over the thigh or the upper leg over the lower leg during walking, depending on whether the anterior or posterior cruciate ligament is involved.
The rear cruciate ligament in particular prevents the thigh from moving forward, while the front cruciate ligament acts in exactly the opposite way.
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In general, the decision between conservative and surgical treatment of a posterior cruciate ligament rupture must be made.
This must be considered and decided individually. It is also important to take into account the patient and his or her expectations. While older, non-athletically oriented people have different expectations regarding the load possibilities of their cruciate ligaments than, for example, competitive athletes, surgery for a torn posterior cruciate ligament is more likely to be induced in a competitive athlete than in a person who can be free of complaints without surgery.
From a medical point of view, there is no clear standard to date as to whether a torn posterior cruciate ligament should be treated conservatively or surgically. The representatives of both points of view have their own opinions, which are discussed again and again.
For example, there are doctors among them who are convinced that arthrosis tends to occur earlier without surgery than with surgery. The following list, therefore, contains advantages and disadvantages, but nothing seems to be as important for the assessment between conservative and operative therapy as the individual consideration and the individual contact of the patient with the treating doctor. Only the doctor can ultimately make an individual decision regarding the form of therapy.
Conservative therapy form of the posterior cruciate ligament rupture
Important indications for the decision for the conservative therapy a posterior cruciate ligament rupture exists particularly in the case of stretching of the posterior cruciate ligament or partial rupture. If a patient with a total rupture of the posterior cruciate ligament is able to compensate for the instability by means of his muscles, the decision is also made here to opt for conservative therapy. As a rule, surgery is not performed on patients who do not participate in competitive sports and are older than 50 years. Even if ligament injuries are already older than 14 days, conservative therapy is generally used.
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However, it is important to note that conservative therapy for a posterior cruciate ligament rupture can only be successful if the patient carries out the necessary training independently on a daily basis. The motivation of the patient is therefore particularly important and must also be discussed with the patient before the decision regarding the form of therapy is made.
The conservative form of therapy for a torn posterior cruciate ligament usually begins immediately after the acute pain has subsided with full loading, but in conjunction with an individually adapted plastic splint and physiotherapy. The aim of conservative therapy is to improve muscle strength through exercises that are simultaneously designed to improve the stability of the affected knee joint.
It is the muscles that are supposed to take over the function of the torn cruciate ligaments so that the individual assistance and motivation of the patient discussed in the previous paragraph must be made clear here once again with regard to the success of the conservative therapy of the torn posterior cruciate ligament.
In addition to the actual therapy:
- Stimulation current,
- Ultrasonic and/or
- Ice treatment
can be integrated. Combinations of these treatment methods are also conceivable in the case of a posterior cruciate ligament rupture and aim to improve blood circulation and ultimately also to reduce pain.
Surgery for a posterior cruciate ligament rupture
Arthroscopic surgery of the posterior cruciate ligament rupture
Which tendon is ultimately used is multifactorial and can be seen individually. The decisions depend on individual indications:
- Sports activity
- Complex knee ligament injury
- Bony outline
- Overall status
- Additional Violations
- Rupture of the cruciate ligament with additional meniscus lesion close to the base
Even though the description of the surgical techniques seems to be quite complicated, the success rates seem good to satisfactory, especially in cases without significant additional injuries.
The surgical therapy form is usually followed by a consistent follow-up treatment (rehabilitation). These measures can take an average of about 3 months to complete, although full loading is usually only achieved after 6 months.
A posterior cruciate ligament injury usually represents a serious injury. The prognoses for regaining full weight-bearing capacity are to be regarded as rather unfavorable, irrespective of the decision whether conservative or surgical treatment should be applied. Either way, the patient’s help and above all his patience is required.
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The pictures show the procedure for cruciate ligament plastics. While patellar tendon plastic surgery usually involves removal of the middle third of the patellar tendon including adjacent bone blocks (left picture), semitendinosus tendon and/or gracilis tendon are separated from the bone arthroscopically via a small skin opening and separated from the respective muscle belly by means of “strippers” (right picture). The resulting remnants of the tendons scar with their respective surroundings without any significant loss of function.
As a result of serious accidents, partial ruptures of the anterior and posterior cruciate ligaments occur, so that operative both cruciate ligaments have to be replaced. See anterior cruciate ligament rupture. Usually these two operations are then performed as part of a more complex operation.
The reason for this is not only that only one operation has to be scheduled, but also that if the two operations were to be performed at different times, too much scar tissue would be formed in the meantime, which would make it unnecessarily difficult to perform another cruciate ligament operation.
The risk of infection is also not insignificant with such a procedure.
In most cases, both cruciate ligament plastic surgery using the patellar tendon (patellar tendon) and cruciate ligament plastic surgery using the middle semitendinosus or gracillis tendon are used.
As a rule, the anterior cruciate ligament is replaced with the patellar tendon, the posterior cruciate ligament with the quadruple semitendinosus tendon. In order to keep the scarring of an operation to a minimum, the operation should be performed arthroscopically if possible. Such operations use a highly sophisticated procedure.
Since a posterior cruciate ligament injury is usually a severe injury, the prognosis for regaining full resilience under both conservative and surgical therapy is rather unfavorable.
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Summary of the therapy
Conservative therapy consists of immobilizing the leg affected by a torn posterior cruciate ligament with the aid of a special splint in order to achieve a fusion of the parts of the injured cruciate ligament.
This so-called PTS-splint (PTS = posterior tibial support) is a splint for the lower leg with a calf cushion which acts as a cushion to prevent the lower leg from sinking back. This splint for immobilization after a posterior cruciate ligament rupture must be worn for a total of six weeks both during the day and at night.
If there is no pain, a load is possible, but bending movements must not be performed under any circumstances, as otherwise it is not possible for the torn cruciate ligament to grow together.
After these six weeks, movement exercises without a splint should be performed in the prone position after a torn posterior cruciate ligament. The purpose of this training is to strengthen the thigh extensor (Musculus quadriceps). It is also important here to limit flexion in the knee joint:
A maximum of 60 to 70 degrees of flexion may be performed. From the ninth week onwards, wearing the splint at night is sufficient. From this point on, flexion is possible up to 90 degrees. A complete healing of the posterior cruciate ligament usually takes about twelve weeks.
The alternative to conservative therapy of a torn posterior cruciate ligament is surgical treatment.
The indication for surgery is given in the case of bony tears of the posterior cruciate ligament, in the presence of concomitant injuries or in the case of severe instability of the knee.
The surgical procedure consists of an arthroscopic treatment, which means a mirror image of the joint (arthroscopy) with simultaneous surgical manipulation of the joint structures without a complete opening of the joint.
For this purpose, a few small punctures are made and an incision about four cm long. A person affected by a posterior cruciate ligament rupture receives a posterior cruciate ligament plastic or PCL replacement plastic (PCL = posterior cruciate ligament). Such a plastic is usually made from the patient’s own tendons. The tendons of the musculus semitendinosus or the musculus gracilis of the injured leg are preferred as the material for the therapy of a posterior cruciate ligament rupture.
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This tendon is reinforced with sutures and inserted into predrilled channels in the lower leg and thigh at the attachment points of the original posterior cruciate ligament, where it is then fixed. It is fixed with the help of screws and metal plates.
Since these materials are resorbable, i.e. they dissolve by themselves after a certain time, metal removal at a later date is not necessary.
If the body’s own tendons, which are used for cruciate ligament plastic surgery, have too little tensile strength, artificially produced materials are used. If there are other accompanying injuries to the knee joint in the case of a posterior cruciate ligament rupture, these are also treated in the same session. For example, posterior or lateral capsule-ligament structures can also be replaced by the body’s own tendon components.
After the operation, a drainage is inserted into the knee joint, through which wound secretions and blood can drain away. This drainage is usually removed the next day. Overall, the operation for a torn posterior cruciate ligament takes about one to two hours.
After the operation, the further procedure consists of elevating and cooling the affected leg.
Stretching movements must not be performed and physiotherapy exercises to build up the muscles of the leg should be started. In addition, the surgeon must apply an extension splint for about six weeks.
After this period, he or she will receive a movable splint (PCL orthosis) and may begin with slow bending exercises in the prone position up to 60 to 70 degrees. Furthermore, training of coordination is useful. Sport should be avoided for a period of one year after surgery for a torn posterior cruciate ligament.
If a rupture occurs in the cruciate ligament that has been surgically inserted, the therapy consists of a revision cruciate ligament plastic, which is also surgical.
In this case, the material used is the tendon of the semitendinosus muscle of the other leg or the tendon of the quadriceps muscle. In some cases the operation is performed in two stages. This means that in a first operation, the drill channels of the first cruciate ligament plastic are first filled with bone marrow from the iliac crest (spongiosaplasty) and the actual cruciate ligament plastic is only performed in a second session after about three months, as it is then possible to drill again into the bone to anchor the plastic.
If chronic instability is already present after a posterior cruciate ligament rupture, treatment can be either conservative or surgical. The decision depends on the extent of the instability as well as the complaints in everyday life.
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Duration of a torn posterior cruciate ligament
After a posterior cruciate ligament rupture, pain can still occur during sports even after successful therapy.
The healing period of a torn posterior cruciate ligament is usually relatively time-consuming.
In the course of healing, however, the joint can usually be subjected to gradually increased stress. The duration of a complete healing process, which includes stability and functionality of the joint as before the trauma, depends crucially on the extent of the injury, individual factors of the affected person and the chosen treatment method.
For simple injuries in young patients who are treated conservatively, complete healing can be achieved after about 12 weeks. Surgical treatment of a torn posterior cruciate ligament is chosen when the injury is highly unstable. The healing time for surgical treatment of the injury is also influenced by individual factors.
However, a healing period of at least 12 weeks can be assumed.
The duration of a sick note written due to a torn posterior cruciate ligament usually varies depending on the activity performed. For example, a person who performs heavy physical work at work usually has to be written off sick longer than other people affected. Since the beginning of the therapy is aimed at a strict protection of the joint, a sick leave of at least one to two weeks is to be assumed.
In the course of healing, the injury can be examined and the sick leave extended if necessary.
The resumption of sporting activities may be delayed beyond the specified times. This depends on the individual healing progress and the type of sport performed.
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