The meniscus is two crescent-shaped cartilage discs that connect the upper and lower leg. Injuries, as well as joint wear and tear, can cause damage to the meniscus – for example, a meniscus tear or a meniscus contusion. Typical symptoms that indicate an acute meniscus injury are severe pain in the knee. If a meniscus tear is present, it must be treated in any case to avoid long-term damage to the knee. However, surgery is not always necessary.
Meniscus: cartilage disc in the knee.
The two menisci in the knee play an important role in transferring force and pressure from the thigh to the shin. They align the rounded thigh bone with the straight lower leg, increasing the contact area between the two bones. Because the menisci have great elasticity, they are also good at cushioning shocks from the upper leg to the lower leg – so they have a shock-absorber-like function. In addition, the menisci are probably also important for the distribution of synovial fluid. Together with the ligaments, they additionally contribute to the stabilization of the knee joint.
Degenerative changes in the knee
Just like other cartilage surfaces, degenerative changes occur in the meniscus over time. Since the meniscal tissue is not directly supplied with nutrients, but only indirectly nourished by the synovial fluid, the ability of the meniscus to regenerate is limited. With age, the cartilage tissue becomes brittle due to the lack of regenerative capacity and fine cracks can form. These cracks can then result in a meniscus tear even with a small load. The greater the stress on the meniscus, the earlier such signs of wear can occur – sometimes they can even be observed in younger people who put a lot of strain on their knees. About half of all meniscal lesions are caused by degenerative changes.
Causes of meniscus injury
Injuries to the meniscus primarily affect athletes, as well as people whose occupations place heavy stress on their knees. During sports, a meniscus injury can occur either during rapid rotation or rapid bending and stretching of the knee joint. Typically, a meniscus injury occurs after a twisting and falling motion. In this case, it can happen that the meniscus edge gets between the joint bodies and tears. Sports in which meniscus injuries are particularly common include ball sports such as soccer, handball and basketball, as well as tennis, skiing, karate and cycling. In sports, a meniscus injury is often preceded by wear and tear of the meniscus discs – but in rare cases, a violent impact can also cause injuries to a meniscus that is still completely intact. Often, injuries to the meniscus occur together with other knee injuries, such as a torn cruciate ligament.
Meniscus tear: symptoms
Meniscus tears that occur as a result of an accident and are not degenerative are especially experienced as very painful. If the torn meniscus parts get between the joint surfaces, this leads namely to strong pain in the knee. If, on the other hand, the cause is a degenerative change in the meniscus, increasing pain in the knee joint, which occurs primarily during weight-bearing, is a typical symptom. In the case of meniscus damage, the affected knee joint can usually no longer be moved and loaded properly. It is particularly common to observe that the knee can no longer be fully extended. If a piece of the meniscus is torn off, the affected patient has the feeling of having a foreign body in the knee. In addition, a cracking sound in the knee is often another symptom that indicates meniscus damage. The injured meniscus can cause damage to the articular cartilage, as it is now under greater stress. The substances released during the breakdown of the articular cartilage can cause an inflammation in the knee – a so-called joint effusion. This is characterized by severe swelling and by overheating of the knee.
Diagnosis of a meniscus tear
If pain suddenly occurs in the knee, you should immediately cool the injured knee to prevent excessive swelling of the joint. Also, elevate the leg and move it as little as possible.If there is a suspicion of meniscus damage, a doctor should be consulted immediately. Treatment of a meniscus tear is unavoidable, as it cannot heal on its own due to the lack of blood flow to the meniscus. The attending physician can make an initial diagnosis through various manual tests. This is then supported by an X-ray examination or magnetic resonance imaging. In the case of meniscus damage, a distinction is made between an injury to the inner meniscus and the outer meniscus. Injuries to the inner meniscus occur much more frequently because the inner meniscus is firmly fused to the inner ligament and the joint capsule and is therefore not particularly mobile.
Different forms of tears
If a tear develops in the meniscus, a distinction can be made between different types of tears:
- Radial tear
- Lap tear
- Basket handle tear
- Complex crack
MRI can diagnose about 90 percent of all meniscus tears. Nevertheless, there are some cases in which a clear diagnosis can not be made in this way. If symptoms persist, a knee arthroscopy is then performed, where, if damage is present, it can be repaired directly.
