The meniscus is a crescent-shaped cartilage system in the area of our knee joint. In each knee there is a so-called outer and inner meniscus. Due to their position between the thigh and lower leg bones, the menisci act as shock absorbers by cushioning forces acting on the knee joint, for example when jumping from a greater height.
They also ensure even pressure distribution and compensation for unevenness between the joint surfaces within the knee joint. They increase the contact surface of the joints. The menisci thus protect the joint cartilage and participate in the distribution of synovial fluid within the knee.
The synovial fluid enables sliding painless movements. The so-called outer meniscus, which is located laterally in the knee joint, has a greater range of motion than the relatively immobile inner meniscus. Unlike the inner meniscus, it is not connected to the ligaments of the joint capsule.
This circumstance explains the much more frequent injury to the inner meniscus. If an injury of the outer or inner meniscus occurs, it is called meniscus damage. In this case, tears in the fibrous cartilage of the meniscus occur, which lead to an impairment of its functionality within the knee joint. Meniscus damage is a relatively common injury, with men being affected about twice as often as women.
Causes
The main causes of meniscal damage are age-related degeneration of the cartilage tissue, the so-called age-related wear and tear, and acute meniscal injury. The fibrous cartilage system of the meniscus suffers a loss of substance with increasing age and permanent strain, which leads to its weakening. This results in a reduced resistance and elasticity against forces acting on the knee joint.
The risk of meniscus damage increases. Since the meniscus is nourished indirectly via synovial fluid, such damage has only a limited ability to regenerate. The meniscus tissue becomes brittle, gaps form within the cartilage and the risk of tearing increases.
This progressive loss of substance is completely normal after a certain age and occurs approximately from the age of 40. However, some professions, professional sportsmen and women or leisure activities carry an increased risk of premature wear. For example, tilers or skiers are exposed to increased knee stress.
Meniscus damage due to an acute injury is usually caused by so-called “twist-fall accidents”, which are frequently encountered in sports with footballers or skiers. Here, the knee is usually fixed by the body weight and the foot is turned away at the same time. These pressures and forces, which are applied at an angle from the side, cannot be absorbed well by the menisci and cause meniscal damage, especially if the meniscus is already damaged.
Direct violent impacts or jumps from great heights can also cause meniscus damage. A much rarer cause of meniscus damage is the genetically determined disc meniscus. Here the meniscus is designed as a flat disc, in contrast to the normal half-moon to sickle-like form. This pathological deformation reduces the contact surface and the load on the meniscus increases. Due to this, the above mentioned wear and tear symptoms occur prematurely and the meniscus is highly susceptible to damage.
