Meniscal lesions and rupture of the meniscus
The most common injuries to the knee are those affecting the meniscuses, two small fibrocartilaginous C-shaped structures placed between the femoral condyles and the tibia. The meniscuses allow a better distribution of the loads on the articular cartilage, attenuating them and at the same time guaranteeing the correct mechanics of the movement.
During a trivial movement or following a trauma, the meniscus can remain pinched between the tibia and the femur, tearing like a piece of fabric stuck in a door.
Fortunately our body is much more efficient and resistant than any mechanical gear designed by man even if, unfortunately, the regenerative capacity of the meniscus is very low. These structures, in fact, despite being quite vascularized at the extremities, have a large central portion without capillaries. Without blood the cells of injured menisci cannot heal and heal. If we exclude the cases in which the lesion is limited and extended only to one end, a broken meniscus does not therefore have any regenerative capacity.
Classification and causes of meniscal injuries
Meniscal tears can be classified into two large groups:
Meniscal injuries of traumatic origin: they are more frequent among young people and sportsmen. In these cases one or both menisci undergo injuries following a violent stress that supersedes the maximum resistance of the cartilaginous tissue that composes them
Meniscal lesions of degenerative origin: the meniscus is damaged following an apparently trivial movement such as rising quickly from a squatting position. These lesions arise due to the degeneration of the meniscal tissue which becomes more fragile and less elastic over the years
The lesion can practically affect any point on the meniscus. However, breakages limited to the front horn alone are rather rare. Usually the lesions initially hit the posterior horn and eventually extend to the central body and the front horn. Often these tears are associated with broken ligaments, especially when the medial or internal meniscus is involved. The lesion of this meniscus is about five times more frequent than that of the lateral meniscus due to its greater degree of mobility.
CAUSES: the meniscus is particularly vulnerable when compression forces associated with twisting forces are applied to it. It follows that most of the traumatic events occur when the knee undergoes a torsion trauma. If the trauma is applied when the joint is rotated externally (external rotation) there is a greater risk of damaging the medial meniscus and vice versa.
Other times a meniscal rupture occurs as a result of hyper-flexion or hyperextension movements, for example by giving a vacuum kick.
As we have seen, meniscal fibrocartilages lose some of their elasticity over time and are more subject to wear. For this reason, many elderly meniscal tears are the result of insignificant traumas, such as the act of squatting. A little like what happens with old shirts worn by frequent washing, even the meniscuses can thus be torn off during normal movements.
Symptoms
The main symptoms of meniscal tears include local pain and swelling. These two symptoms are often associated with failure and blockage of the joint caused by meniscus fragments that interfere with normal knee mobility.
The pain increases in the position that generated the meniscal lesion, for example during its rotation or pressure. Following a meniscal injury the subject complains:
- inability to fully extend or flex the joint
- inflammation of the membrane leads to increased production of fluid that collects in the joint cavity (hydrart)
- crunch of the joint associated with pain
SYMPTOMS for clinical diagnosis:
- pain evoked during particular movements: in case of lesion of the medial meniscus the pain is localized above all in the inner part of the knee during hyperflexion, hyperextension or extra-rotation at 90 ° bent knee; for the lateral meniscus the opposite is true (pain externally localized in hyperextension, hyperflexion or internal rotation of the leg and foot with the knee flexed between 70 ° and 90 °)
- loss of strength or hypotrophy of the quadriceps
Diagnosis
The diagnosis of a meniscal injury is basically clinical. The doctor, in his clinic, will seek the presence of the diagnostic symptoms described above. If at least three signs are present at the same time, the diagnosis of meniscal injury, lateral or medial, depending on the case, is considered almost certain.
In any case, the diagnosis must be confirmed by an instrumental investigation.
The X-ray does not provide direct information on the state of health of the meniscus, since this is not a calcified structure, but it can still be useful to exclude other pathologies (arthrosis).
MRI can instead provide clear information on soft tissue status, including menisci. Thanks to these characteristics, the MRI can highlight any degenerative processes before the meniscus breaks.
Also the TAC provides useful information but less precise and detailed with respect to resonance. This technique is less expensive, has shorter waiting lists, shows very well the health of bones but provides little information on the meniscuses.
Lastly, let us remember the arthroscopy, which despite being invasive, represents the safest method to confirm the diagnosis of meniscal injury.
CONTINUE: Treatment of meniscal tears »
