The meniscus is a crescent-like chondral structure that is found between the femur and the tibia and functions as a “shock absorber” in the continuous movements of the knee. Each knee has two menisci, the medial and the lateral.
The healthy meniscus is, as mentioned above, crescent-shaped and firmly attached to the tibia. In the case of a discoid meniscus the shape changes and its thickness increases. More specifically, the meniscus has an oval (ellipsoid) shape while being much thicker than normal. This type of meniscus is more prone to injuries than normal.
A large number of people with discoid meniscus may not experience any problems during their lifetime. However, some of them will develop during early childhood symptoms associated with discoid meniscus.
The meniscus acts as a “shock absorber” between the femur and the tibia. At the same time it protects the fine articular cartilage that covers the ends of the bones and helps the knee to bend and extend. Each knee has two menisci, the medial and lateral one, held together by strong ligaments; the latter supply blood to a small part of the menisci.
Often, the discoid meniscus is circular or ellipsoidal rather than crescent-shaped. It is more common on the outer side of the knee (lateral meniscus) and can affect both knees.
TYPES OF DISCOID MENISCUS
There are three types of discoid meniscus:
- Incomplete: The meniscus is slightly thicker than normal, but retains its crescent shape
- Complete: The meniscus completely covers the tibia
- Wrisberg ligament: The quasi-normal meniscus exhibits high mobility but has lost its posterior meniscus adhesions. Only the menisco-femoral ligament (Wrisberg) is preserved.
DISCOID MENISCUS INJURIES
The discoid meniscus is more prone to injuries than a regular meniscus. Its thickness and irregular shape increases the likelihood of being crashed between the femur and tibia. In the event of injury to the ligaments that hold the meniscus in place, the risk of rupture becomes even greater.
After injury, meniscus healing is difficult, or even impossible, due to insufficient blood supply. In this way, the necessary nutrients for meniscus reconstruction are not sufficient.
In many cases of discoid meniscus, patients present symptoms without a history of injury.
The causes of discoid meniscus are not known. This is a congenital anatomical variant. Meniscus injuries and ruptures occur due to rotating knee movements during sport activities (quick shifts of direction).
The main symptoms include:
- Stiffness and edema
- Knee blocking
- Instability (sense of knee “out-of-place”)
- Inability to completely extend the knee
After receiving a detailed medical history, the Orthopedist examines the knee. With proper handling, the knee is bent and flexed. In the case of discoid meniscus, a click is felt by the patient and the physician. In severe cases, part of the meniscus protrudes under the skin.
X-rays: They are unable to depict the menisci, but can exclude other accompanying knee injuries. In addition, due to the thickness of the discoid meniscus, the distance between the femur and the tibia on the outer side of the knee is increased.
Magnetic Resonance Imaging: It depicts soft tissues with great precision. It can describe in detail the irregular shape of the discoid meniscus and its possible ruptures. However, type III is difficult to be depicted with MRI, since it can be perceived on the move.
It should be noted that for MRI the patient must remain motionless for 30-45 minutes and many of the young patients require some form of sedation or anesthesia.
Many times, a discoid meniscus is accidentally discovered when examining the knee for other reasons. If it does not cause any of the above symptoms, then you do not need any kind of treatment. Otherwise, the orthopedist may recommend surgery.
Knee arthroscopy is one of the most common orthopedic surgeries. During arthroscopic surgery, the surgeon inserts a camera into the joint through some very small incisions. With the help of a camera and special tools, the doctor can repair meniscus ruptures, cruciate ligament ruptures and several other intraarticular injuries. In most cases the patient is discharged and returns home on the same day.
So that the patient does not feel pain during surgery, the patient is anesthetized. There are several types of anesthesia: The local and peripheral which anesthetize only parts of the body and the patient remains awake. General anesthesia totally sedates the patient. In most cases of arthroscopic surgeries general anesthesia is used.
It mainly depends on the type of discoid meniscus.
The complete & incomplete types, without concomitant lesions, are treated with the saucerization method, in which part of the meniscus is preserved.
If the disc meniscus is accompanied by a rupture, the surgeon remodels the meniscus (meniscoplasty) and then removes the pieces or fixes them with stitches.
In the case of type III discoid meniscus, meniscoplasty is performed and it is stabilized by sutures.
After surgery, the knee is immobilized with a splint or elastic band. Crutches are first used for a short period of time, and a wheelchair is used at very young ages. Finally, the Orthopedist recommends physiotherapy to restore knee strength and mobility.
Most patients recover fully after meniscoplasty. However, if a large part or the entire meniscus is removed, it can lead to osteoarthritis of the knee. Sometimes and depending on the case, the orthopedist may recommend avoiding sports that overload the knee joint, such as football, tennis, basketball and more.