Cruciate Ligament Injuries
In contrast, tears of the anterior cruciate ligament are very common sports injuries. It can tear, among other things, when the lower leg is fixed and there is a rotation of the upper body with the knee bent and loaded laterally. It does not take outside force to tear the anterior cruciate ligament. The long levers on the knee joint create very high forces on the ligaments of the knee. An intact anterior cruciate ligament endures forces in the range of 1800-2500 Newtons until it tears.
Since the anterior cruciate ligament restricts the forward movement of the lower leg relative to the thigh, instability in this direction can occur after a tear. After the acute symptoms have subsided (after a few days to weeks), many patients therefore develop a certain feeling of insecurity, the knee gives way when walking on uneven terrain, especially in situations where one does not consciously concentrate on walking. In addition, recurrent pain is common, as overuse and minor injuries to the knee joint occur due to the increased joint motion
Examinations
The suspicion of a cruciate ligament injury arises when a corresponding injury event is reported by the patient and the above-mentioned phenomena exist. In the acute situation, it may be impossible to examine the knee and make an appropriate diagnosis due to pain. There is no compelling need for immediate surgical intervention, as is often required for fractures. The latter, however, must be ruled out by radiography, since the same mechanism that leads to tearing of the cruciate ligament can also lead to fracture of the tibial plateau, for example. After the acute symptoms have subsided, the physician can usually determine the instability during clinical examination of the knee.
If the findings are clear, further examinations are not necessary. More often, however, magnetic resonance imaging (MRI) is ordered because of its high sensitivity for diagnosing cruciate ligament injuries and its ability to detect possible concomitant injuries to the menisci and cartilage.
Treatments
Unlike other ligament injuries, for example those of the medial collateral ligament of the knee, the cruciate ligament shows no significant tendency to heal. Nevertheless, surgical reconstruction is not always necessary. The cruciate ligament is supported in its function by the collateral ligaments, the knee joint capsule and, above all, the thigh muscles. The actual resulting instability may therefore be relatively minor and not necessarily accompanied by significant discomfort. Particularly in older patients without a greater demand for activity, a satisfactory situation can certainly be achieved with conservative therapy. In younger age groups, however, another argument comes into play in addition to the generally higher athletic demands: the increased joint play leads to micro-injuries of cartilage and menisci.
Since neither cartilage nor menisci have a good tendency to regenerate, this damage adds up over time, culminating in osteoarthritis. This effect naturally has greater consequences if it occurs earlier in life, although such secondary damage can of course also be found in older patients. In this respect, reconstruction of the cruciate ligament is often appropriate in young, athletically active patients. But even in older people, instability that is perceived as obvious can be a reason for surgery.
Surgical Technology
In the past, attempts were made to suture the torn ligament. In the majority of cases, this did not sufficiently restore the function. Replacement with artificial material, e.g. Kevlar or carbon fibers, has also been disappointing. At present, therefore, the body's own ligaments and tendons are mainly used to replace the torn ligament. So far, part of the patellar tendon has been most commonly used because it has good biomechanical properties and heals well. However, complications are observed due to the removal of the graft itself. The most common is that patients are no longer able to kneel on the affected leg
For this reason, alternatives are increasingly being used, especially tendons that run along the inside of the thigh (so-called semitendinosus and gracilis tendons) and are harvested through a small incision. No significant functional impairment results from the removal of these tendons. At the clinic here, the latter are favored, although other grafts are sometimes used.
The reconstruction of the anterior cruciate ligament is arthroscopically supported, i.e. minimally invasive. It is crucial for later function that the anatomically correct course of the anterior cruciate ligament is restored. The transplant is inserted into tunnels that are drilled into the upper and lower leg bones. There, it is fixed in place using various techniques and materials. We mainly use anchoring materials made of titanium or resorbable plastic-like materials. The latter are made of polylactate or polyglycolic acid and have the advantage that they degrade in the bone over time (months to years). They do not have to be removed and do not pose a technical problem for revision surgery, which is not altogether uncommon.
If necessary, meniscus and cartilage damage are also treated in the same session
The hospital stay is 4-5 days. However, such operations are moving towards as outpatient procedures.
Nachbehandlung
Der Nachbehandlungszeitraum ist recht lang. Dies begründet sich darin, dass das Transplantat in Abhängigkeit von seiner Art 6 Wochen bis 3 Monate zum Einheilen benötigt. Anfangs ist das Transplantat dem natürlichen Kreuzband in seiner Belastbarkeit mindestens ebenbürtig. Es wird allerdings im Kniegelenk umgebaut und durchläuft dabei eine Phase verminderter Belastbarkeit. Dieser Umbau beansprucht Monate und kann durch krankengymnastische Maßnahmen und ähnliches nicht wesentlich beschleunigt werden.
Daher ist es in der Regel erst nach 8-9 Monaten wieder möglich, kniebelastenden Sportarten (Fußball, Tennis, Alpinski u.ä.) nachzugehen. Leichtes Laufen und Fahrradfahren ist nach etwa 3-4 Monaten wieder möglich. In der Frühphase wird meist eine intensive krankengymnastische Behandlung durchlaufen, häufig mit einer ambulanten Rehabilitationsmaßnahme. Entscheidend ist, eine gute muskuläre Stabilisierung des Kniegelenkes zu erreichen, was letztlich auch Kriterium für die Wiederaufnahme entsprechender sportlicher Betätigung ist. Das Wiedererlangen der Arbeitsfähigkeit hängt naturgemäß von der Art der beruflichen Betätigung ab, bei Berufen ohne körperliche Belastung kann dies schon nach 2-3 Wochen der Fall sein, häufig vergehen aber 6 Wochen und mehr.
Ziel der Kreuzbandrekonstruktion ist es, eine ausreichende Stabilität des Kniegelenkes zu erzielen. Idealerweise gelingt es, das frühere Niveau sportlicher Aktivität wieder zu erreichen. Da eine Kreuzbandrekonstruktion nur Ersatzcharakter haben kann und selten die Funktionalität des natürlichen Kreuzbandes erreicht, wird es nicht immer möglich sein, wieder an das ursprüngliche Niveau anzuknüpfen. Auch herrscht eine gewisse Uneinigkeit in der wissenschaftlichen Literatur darüber, wie zuverlässig durch eine Rekonstruktion des Kreuzbandes spätere Schäden am Knorpel und den Menisken verhindert werden können.
Aus diesen Gründen hat die nicht-operative Behandlung weiterhin ihre Bedeutung, sofern sich damit eine zufriedenstellende Stabilisierung erreichen lässt.
Spätkomplikationen
Ein rekonstruiertes Kreuzband kann wieder zerreißen, naturgemäß vor allem dann, wenn der ursprünglich zur Zerreißung führende Sport wieder ausgeübt wird. Insgesamt sind Verletzungen rekonstruierter Kreuzbänder häufiger als die des natürlichen Kreuzbandes, da die Biomechanik nur unvollständig wiederhergestellt werden kann. Auch werden überschießende Narbenbildungen innerhalb des Knies beobachtet, was zu Einschränkungen der Beweglichkeit führen kann.