Meniscus are two fibrocartilaginous structures: an internal (medial) C-shaped and an external (lateral), whose shape can be compared to an O. Both are present in the knee and can be compared to squid rings, almost circular and of very similar consistency, triangular section, with a concave upper and a flat bottom.
What is the function of the meniscus?
Its main function is, according to experts in Traumatology , to reduce the direct contact of the femur with the tibia, in order to facilitate the movements of the joint and to avoid the wear that would involve a direct friction of the surfaces of both bones, as well as to stabilize the articulation and modifying the vectors of force of the load on the knee.
This form in CO and its triangular section are fundamental to act as a kind of pads , resistant but not rigid, providing better congruence to the bones, so that forces and pressures are distributed.
The meniscus explained "in the kitchen"
Previously, they have been compared to "squid rings", and since the femoral condyles of the knee are convex, they are now going to compare with an egg. As the tibial plateau is flat, it will be compared to a plate. Thus, we could imagine the menisci as a squid ring, which is placed on a plate on which is laid an egg. In this culinary example, the fact that the meniscus section is triangular, with a concave surface on its upper face and flat on its lower face, increases the contact surface with both the tibia (flat) as with the femur (convex), increasing the stability of the system and decreasing the contact area of the hyaline cartilage of the femoral condyle on the tibia. Thus, when we apply load on the femoral condyle (by jumping for example), that force of impact falls on the menisci and the force vector is transformed towards the periphery, reducing the load on the femoral condyle and the tibia.
Returning to the "kitchen": the egg maintains the balance better on the squid, there is less contact zone of the egg directly on the plate, reducing the impacts and descaling of the surfaces. By squeezing the egg against the plate, the squid ring would make a protective pad cushioning the impact and preventing the surface of the egg or dish from breaking.
The vascularization of the meniscus
The fact that they are cartilaginous structures makes blood irrigation very scarce and for that reason the scarring capacity of the menisci when they are injured is very reduced.
Why Meniscus Breaks
Although the meniscus are fibrocartilaginous structures, not rigid and with relative elasticity, it is not uncommon to be injured. A violent or non-violent movement of the knee, especially if the joint is semi-flexed, can cause injuries of different types : a detachment, a tear or a rupture thereof. This is especially true in sports. For example, when an athlete spins abruptly while the foot remains fixed to the ground, it causes a rotational movement of the femur over the tibia with the meniscus interposed between them.
However, it can also occur in any situation of everyday life, for example as we walk down the street and we turn for something that catches our attention, or we simply squat to tie our shoes. This is because the menisci are not fixed, but have some ability to move, moving forward and back to maintain a good congruence of the femur with the tibia.
The Importance of Meniscus Surgery
In addition to being a stabilizing complex, the menisci have a protective mission of the articular surfaces, and with it, a protective function of the cartilage that surrounds the bone.
A rupture of a meniscus implies a loss of the functions of the meniscus in the area where the rupture occurred. Thus, the capacity for protection and stabilization in this area disappears, the articular cartilage is unprotected and evolves towards osteoarthritis.
Meniscal rupture surgery
Meniscal rupture surgery is performed by arthroscopy , with 2 millimetric wounds, anesthetizing only the leg. Clinical discharge can occur after 4 or 5 hours after the intervention, and the patient can walk without crutches with two possibilities:
• Meniscal suture : the rupture of the meniscus is cured, and once healed, it regains its full functionality again. Due to its capricious irrigation, only certain types of meniscal breaks can be sewn with sufficient guarantee.
• Partial menisectomy : only the part of broken meniscus is removed, leaving all the rest of the meniscus healthy.
Why to operate the meniscus
There are many factors that influence, including the age of the injured patient, the degree of osteoarthritis of the knee, the pain of rupture, the occurrence of episodes of joint blockage ...
In an older person , rupture of the meniscus should be operated when the discomfort is not alleviated, despite the fact that it takes 3 or 4 months of evolution with conservative measures and symptomatic treatment.
In the case of rupture occurring in a young person , it must always intervene, since in the case that it could be suturable, over time can be transformed into not suturable, in addition the rupture could increase in size and if the fragment broken is unstable, can strike in flexo-extension and rotation against femur cartilage, increasing chondropathy and wear of hyaline cartilage.