Generality
The medial meniscus is the cushion of fibrous cartilage, belonging to the knee joint, which sits above on the tibia, on the medial portion of the tibial plateau.
Similar to a crescent or a C, the medial meniscus is a poorly mobile structure, maintained in position by the medial and transverse collateral ligaments, and by insertions at the level of the anterior and posterior intercondylar fossa of the tibial plateau.
Thanks to the support of a very similar element - the lateral meniscus located on the lateral surface of the tibial plateau - the medial meniscus covers various functions, including: protecting the knee from the effects of improper movements, absorbing shocks and cushioning the weight of the knee, to prevent the direct collision between the femur and tibia, to favor the correct distribution of the synovial fluid, etc.
The medial meniscus can be a victim of injury; medial meniscus injuries are among the most common knee injuries.
What is the Medical Meniscus?
The medial meniscus, or internal meniscus, is the semi-crescent-shaped layer of fibrous cartilage, which takes place in the medial portion of the knee, between the medial condyle of the femur and the medial condyle of the tibia.
The medial meniscus is a fundamental component of the knee joint and, together with the lateral meniscus (or external meniscus ) and articular cartilage, constitutes the so-called cartilage of the knee .
Brief review of the medial-lateral terms
Recalling that the sagittal plane is the anteroposterior division of the human body from which two equal and symmetrical halves are derived, " medial " means "near" or "closer" to the sagittal plane, while " lateral " means "far" or " farther "from the sagittal plane.
Example to understand:
- The second toe is lateral to the big toe, but is medial to the third toe.
To understand: Anatomy and Function of the Knee
The knee is the important synovial joint of the human body, placed between the femur (superiorly), tibia (inferiorly) and patella (anteriorly).
The knee includes several structural elements, including:
- The synovial membrane, which covers the joint from the inside and produces synovial fluid, a fluid with a lubricating action for all the internal structures of the knee;
- The collateral ligaments, the cruciate ligaments and the patellar tendon, which, all together, guarantee the stability of the joint and the right alignment between the femur and tibia;
- The synovial bags, which are small synovial membrane pockets, filled with a lubricating liquid very similar to the synovial fluid;
- The articular cartilage, which covers the lower surface of the femur, the inner side of the patella and the center of the upper surface of the tibia, protecting all these bones from mutual rubbing;
- The medial meniscus and the lateral meniscus, which are cartilage cushions with shock absorbing and anti-rubbing function, located on the sides of the upper surface of the tibia.
Thanks to its strategic position and its particular anatomy, the knee plays a fundamental role in supporting the weight of the body and in allowing the movements of extension and flexion of the leg, during a walk, a run, a jump etc.
Anatomy
The medial meniscus is comparable to a pad of pure fibrous cartilage, which, in appearance, resembles a half-moon or the letter C.
Of whitish color, the fibrous cartilage is the type of cartilage in the human body that is more resistant to mechanical stress.
Precisely because of this enormous resistance, it is the cartilaginous variant most present at the level of the mobile joints (eg: knee, ankle, shoulder, etc.), where it is necessary to preserve the ends of the bones involved by the consequences of friction, rubbing and loads of weight.
Did you know that ...
All types of cartilage present in the human body are made up of particular cells, called chondrocytes, and are poor, if not completely devoid of blood vessels.
Location of the Medial Meniscus
The medial meniscus extends over the medial portion of the so-called tibial plate ; the latter is the particular structure which constitutes the upper surface of the tibia and which houses, in addition to the medial meniscus, also the lateral meniscus (on the lateral portion) and the insertions of the anterior cruciate and posterior cruciate ligaments .
The medial meniscus then locates on the apical surface of the tibia, which is the bone which, together with the fibula, constitutes the skeleton of the leg .
Imagining to look at a human body from the front and focusing on the knee, the medial meniscus at the base of the patella, on the inner side of the upper limb, facing the medial meniscus of the contralateral knee.
Readers are reminded that the "medial" anatomical term is synonymous with proximity to the sagittal plane, ie the anteroposterior axis that symmetrically separates the human body into two halves, a right half and a left half.
Structure and Aspect: the details
With its anterior extremity - which is thin and pointed - the medial meniscus attaches to the so-called anterior intercondylar fossa of the tibial plateau.
The anterior intercondylar fossa of the tibial plateau is a rough depression, on which the anterior cruciate ligament of the knee and the anterior part of the lateral meniscus are also inserted.
Here, the medial meniscus is located in front of the anterior cruciate ligament.
With its posterior end, however, the medial meniscus joins the so-called posterior intercondylar fossa of the tibial plateau.
The posterior intercondylar fossa of the tibial plateau is a rough burial - exactly like the anterior intercondylar fossa described above - on which the posterior cruciate ligament of the knee and the posterior part of the lateral meniscus are also inserted.
Here, the medial meniscus is located between the lateral meniscus and the posterior cruciate ligament
The medial meniscus is connected to two ligaments:
- The internal collateral ligament of the knee, which is one of the 4 so-called knee ligaments (together with the aforementioned anterior cruciate ligament and posterior cruciate ligament and lateral collateral ligament), and
- The transverse ligament, which is the structure responsible for joining the anterior region of the medial meniscus to the anterior region of the lateral meniscus.
Thanks to the connection with these two ligaments, the medial meniscus turns out to be a stable structure, not very mobile .
Imagining to observe the medial meniscus from above, it is possible to notice that it is a crescent with the posterior portion wider than the anterior and with the convexity oriented medially and the concavity that looks towards the lateral meniscus, situated on the opposite side.
Vascularization of the Medial Meniscus
The medial meniscus is mostly devoid of vascularization; the only part of it where there is a noticeable blood supply is the outer edge .
The lack of vascularization means that the medial meniscus is not able to heal spontaneously, in the event that it suffers a lesion (it is in fact the oxygen and nutrients contained in the blood that allow the healing of the tissues victims of injuries, wounds etc.).
Did you know that ...
The doctors define the portion of the vascularized medial meniscus - that is its outer edge - with the expression " red zone ".
By virtue of the network of blood vessels that provides oxygen and nutrients, the "red zone" is the only part of the medial meniscus that can heal spontaneously from injuries against it.
Comparison between Medial Meniscus and Lateral Meniscus
- The lateral meniscus is made up of pure fibrous cartilage, just like the medial meniscus; compared to the latter, however, it has a circular appearance, so that anatomists have the habit of comparing it to letter O.
- The lateral meniscus extends over the lateral portion of the tibial plateau (so it is on the upper surface of the tibia), in a position opposite to the medial meniscus.
- With its front part, the lateral meniscus is inserted at the level of the anterior intercondylar fossa, laterally and just behind the anterior cruciate ligament; with its back, however, the lateral meniscus is inserted at the level of the posterior intercondylar fossa, exactly in front of the posterior end of the medial meniscus.
- Near its posterior portion, the lateral meniscus emits a thick ligament, called the Wrisberg ligament, which joins it to the lateral epicondyle of the overlying femur.
Function
Together with the lateral meniscus, the medial meniscus has the function of:
- Protect the knee joint from possible damage resulting from hyperextension and lower limb hyperflexion;
- Absorb any impact to the joint in the best possible way;
- Amortize the weight of the body and distribute it uniformly over the entire joint (thus avoiding that the weight of the body is concentrated in a single point);
- Prevent the direct collision between the femur and tibia, a collision that would damage these two bones;
- Help the ligaments to stabilize the joint;
- Favor a distribution of the synovial fluid that guarantees the optimal lubrication of the articular cartilage.
Did you know that ...
Knee experts compare the medial meniscus and lateral meniscus with shock-absorbing pads .
diseases
The medial meniscus - as well as the lateral meniscus - can be the victim of injuries, which compromise its integrity and function.
Lesion of the Medial Meniscus: What it is, Causes, Symptoms, Diagnosis and Therapy
WHAT'S THIS
Also known as a lesion of the meniscal cartilage, the lesion of the medial meniscus is a knee injury, characterized by the structural alteration of the layer of fibrous cartilage that constitutes the internal meniscus.
The lesion of the medial meniscus may be more or less severe, depending on the mode of alteration and the position of the latter.
Together with the lesion of the lateral meniscus, the lesion of the medial meniscus represents the most frequent injury to the cartilaginous component of the knee.
CAUSES
In general, the lesion of the medial meniscus is the result of a knee sprain ; knee sprains are acute events, in which the joint in question suffers, following an unnatural movement or a sudden trauma, a temporary modification in anatomy, which leads to damage to its constituent elements.
The lesion of the medial meniscus, however, can also be the result of repeated harmful stresses on the knee, which produce the gradual degeneration of the cartilage located on the tibial plateau.
RISK FACTORS
The injury of the medial meniscus is a common injury during the practice of sports, such as football, basketball, rugby and volleyball, in which the athlete performs jumps, changes of direction etc.
Furthermore, it is more frequent among the elderly (over 40% of cases involve people over the age of 65), as aging results in gradual degeneration of the meniscal cartilage layer.
SYMPTOMS
The typical symptoms of medial meniscus injury are:
- Knee pain;
- Swollen knee;
- Reduced knee mobility;
- Sense of knee stiffness;
- Emission of strange noises from the knee at the time of its movement and articular instability.
Often, the injury to the medial meniscus resulting from a severe knee sprain is associated with another joint injury, more serious than the aforementioned meniscal injury: rupture of the anterior cruciate ligament .
DIAGNOSIS
In general, the procedure of investigations that allows the diagnosis of lesion of the medial meniscus includes: the physical examination, the anamnesis and the magnetic resonance to the knee .
THERAPY
The treatment of the lesion of the medial meniscus varies in relation to various factors, including the severity, location and extent of the injury.
For lesions less severe, small or affecting the part of the vascularized medial meniscus (the so-called red zone), a conservative treatment may be enough, based on: application of ice, rest, elevation of the painful limb, compression and physiotherapy.
On the other hand, for the most serious, large lesions or those affecting the non-vascularized part of the medial meniscus, surgery is indicated for the removal of only the damaged or repairing part (depending on the extent of the accident), since, in addition to the persistence of pain symptomatology, there is the possibility that the compromised cartilage could cause damage to the other neighboring articular components (eg: ligaments).
If they are near the ligaments (therefore there is the risk of indirect damage to these important structures), even the less severe lesions of the medial meniscus require surgery.
