Definition
The inner meniscus is a part of the knee joint. Together with the outer meniscus and the cruciate and collateral ligaments, it plays an important role in the smooth functioning of knee movement. A torn inner meniscus therefore results in pain and a functional restriction of knee movement.
Meniscus lesions in younger people are usually caused by the use of force on the knee, either as a result of trauma (e.g. in an accident) or, for example, by jerky movements during sports, whereby the rotation of the knee with a fixed foot is the most common accident mechanism. For this reason, tears to the inner meniscus are particularly common in sports such as soccer or downhill skiing. Since the medial meniscus is fused to the medial collateral ligament of the knee joint, it has less possibility to “evade” than the lateral meniscus, so that it is much more frequently affected in accidents than the latter.
A typical combination of injuries in the knee joint is the so-called “unhappy triad” consisting of:
- A tear of the inner meniscus,
- An injury of the inner collateral ligament
- And an injury of the anterior cruciate ligament.
In humans over 40 years of age, meniscus damage is often of a degenerative nature, which means that in old age, natural wear and tear leads to the menisci tearing even with little or no external force. There are different types of meniscus tears, each of which describes the form of the tear: Of these, the first two can be observed most frequently. With the flap tear and with the basket handle tear the part of the meniscus loosened by the inner meniscus tear can be pinched.
- Basket handle crack
- Radial crack
- Flap tear
- Horizontal crack
Symptoms
With regard to the traumatic causes based on sporting activity, it is mainly strong shear forces, twisting or dislocation of the knee, falls and an abrupt stop of movement that lead to a meniscus tear, as is particularly common in sports. It can therefore be said that it is precisely the sporting aspect that plays an important role in determining the causes of an inner meniscus tear. The described movements that can lead to a tear occur mainly in sports such as tennis, squash, basketball, soccer and skiing.
Jumps from greater heights also put a knee joint under a lot of stress and can provoke an inner meniscus tear. Apart from acute traumatic causes, meniscus damage can also occur in everyday life. A typical dangerous movement is for example squatting down.
Besides the two main causes, degenerative processes and traumatic events, a genetic, congenital variant of the meniscus also plays a role in the risk of an inner meniscus tear. The so-called “disc meniscus” is a clinical picture in which the menisci have a modified form. Instead of the usual crescent-shaped appearance, the menisci have, as the name already shows, rather the form of a disc. Due to certain pathological processes, the risk of a lesion of the inner meniscus is increased, especially during sports and especially of a torn inner meniscus.
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