There are two menisci in your knee; each rests between the thigh bone (femur) and shin bone (tibia). The menisci are made of tough cartilage and conform to the surfaces of the bones upon which they rest. One meniscus is on the inner side of your knee; this is the medial meniscus. The other meniscus rests on the outer side of your knee, the lateral meniscus.
What does the meniscus do?
These meniscus functions to distribute your body weight across the knee joint. Without the meniscus present, the weight of your body would be unevenly applied to the bones in your legs (the femur and tibia). This uneven weight distribution would cause excessive forces in specific areas of bone leading to early arthritis of knee joint
How does the meniscus work?
The knee joint is very important in allowing people to go about performing almost any activity. The joint is made up of three bones: the femur (thigh bone), the tibia (shin bone), and the patella (knee cap). The surfaces of these bones within the joint are covered with a layer of cartilage. This important surface allows the bones to smoothly glide against each other without causing damage to the bone. The meniscus sits between the cartilage surfaces of the bone to distribute weight and to improve the stability of the joint.
What happens with a meniscus tear (torn cartilage)?
The two most common causes of a meniscus tear are due to traumatic injury (often seen in athletes) and degenerative processes (seen in older patients who have more brittle cartilage). The most common mechanism of a traumatic meniscus tear occurs when the knee joint is bent and the knee is then twisted.
It is not uncommon for the meniscus tear to occur along with injuries to the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL)-these three problems occurring together are known as the "unhappy triad," which is seen in sports such as football when the player is hit on the outside of the knee.
What are the symptoms of a meniscus tear?
Individuals who experience a meniscus tear usually experience pain and swelling as their primary symptoms. Another common complaint is joint locking, or the inability to completely straighten the joint. This is due to a piece of the torn cartilage physically impinging the joint mechanism of the knee.
The most common symptoms of a meniscus tear are:
- Knee pain
- Swelling of the knee
- Tenderness when pressing on the meniscus
- Popping or clicking within the knee
- Limited motion of the knee joint
How is the diagnosis of a meniscus tear made?
Any patient who has knee pain will be evaluated for a possible meniscus tear. A careful history and physical examination can help differentiate patients who have a meniscus tear from patients with knee pain from other conditions. Specific tests can be performed by your doctor to detect meniscus tears.
X-rays and MRIs are the two tests commonly used in patients who have meniscus tears. An x-ray can be used to determine if there is evidence of degenerative or arthritic changes to the knee joint. The MRI is helpful at actually visualizing the meniscus. However, simply 'seeing' a torn meniscus on MRI does not mean a specific treatment is needed. Treatment of meniscus tears depends on several factors, as not all meniscus tears require surgery
What treatments are available for a meniscus tear (torn cartilage)?
Almost any knee injury can initially be treated acutely with ice packs, rest, and immobilization. These simple measures will help to decrease swelling and pain in the joint.
Your physician can use information about how the injury occurred and physical examination tests to determine the likelihood of a meniscus tear. While x-rays are usually normal with an isolated meniscus tear, the MRI evaluation will often reveal abnormalities within the meniscus.
Is surgery necessary for meniscus tears?
The next step is to determine whether or not surgery is necessary for a meniscus tear. If an individual is not a good surgical candidate or if their meniscus tear symptoms are not significant, surgery can often be delayed or avoided altogether. Many people live normal lives despite having a meniscus tear. It is only when the meniscus tear becomes symptomatic, and interferes with activities, that surgery to treat the meniscus tear should be considered.
There are generally two surgical options for treating a meniscus tear:
- Meniscus Repair
A meniscus repair is a surgical procedure done to repair the damaged meniscus. This procedure can restore the normal anatomy of the knee, and has a better long-term prognosis when successful. However, the meniscus repair is a more significant surgery, the recovery is longer, and, because of limited blood supply to the meniscus, it is not always possible.
- Meniscectomy
A meniscectomy is a procedure to remove the torn portion of the meniscus. This procedure is far more commonly performed than a meniscus repair. Most meniscus tears cannot be treated by a repair for a number of reasons. Often the tear is in an avascular region of the meniscus, and will not heal even if repaired. Some tears are frayed and cannot be sutured together. In these cases, the meniscectomy is done to remove the damaged portion of meniscus. The meniscectomy has a faster recovery, but it can lead to trouble years down the road because of the absence of the normal meniscus.
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