The menisci are cartilaginous structures of the knee joint. They are located between the articulating bones, i.e. between the thigh bone (lat. femur) and the lower leg bone (lat.
tibia). The menisci serve to establish better contact between the two bones and compensate for the incongruity due to their different shape and curvature. In addition, they increase the force-absorbing surface in the knee joint and thus ensure a better distribution of joint pressure.
There is an inner and an outer meniscus. Both are anchored to the tibial plateau in a specific region of the bone, the so-called “area intercondylaris anterior and posterior”. The inner meniscus is also connected to the outer ligament (collateral ligament) of the knee joint, making it much less mobile than the outer meniscus. Both have a crescent-like shape; the outer meniscus even represents an almost closed ring.
Torn meniscus
Like any structure, the menisci, an important component of the knee joint, can be damaged. The meniscus tear is the most common injury. This is understood to be an interruption of the continuity of the cartilaginous structure.
It is usually caused by traumatic events or degenerative processes. Strong shear forces, twisting or dislocation of the knee, falls and an abrupt stop of movement can lead to a meniscus tear. Particularly in old age, but possibly also in younger age, signs of wear and tear and overstrain make a meniscus tear more likely.
The inner meniscus is more frequently affected by the knee joint due to its reduced mobility as a result of the additional attachment to the inner ligament. In most cases, the posterior third (inner meniscus horn) ruptures. In addition to the localization of a meniscus tear, different types of tears can be classified (transverse, longitudinal and handle-basket-like meniscus tear).
Diagnostics
If a meniscus tear is suspected, the clinical examination with special tests is the first step. So-called provocation tests enable the detection and differentiation of inner and/or outer meniscus tears by means of compression and rotational loading. Other methods include computer tomography (CT; layered x-ray), ultrasound and, as an invasive method, knee arthroscopy.
In the case of chronic meniscus lesions, arthroscopy may be indicated. Acute/fresh meniscus tears are much more common. Here, MRI (magnetic resonance imaging) is considered the method of choice for imaging procedures.
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