What are Meniscus Injuries?
Meniscus tears are one of the most common knee injuries. They are more common in people over the age of 40. Damage to the meniscus in younger people typically occur with a traumatic injury to the knee like an ACL tear.
Menisci Anatomy and Function
The menisci (plural for meniscus) are two C-shaped pieces of cartilage between the femur (thigh bone) and the tibia (shin bone).
Each knee has two menisci:
- Medial: On the inner side of the knee, this is largest of the two.
- Lateral: On the outer side of the knee.
The menisci serve two important roles. First, they help to improve the fit between the femur and tibia. Second, the menisci act as shock absorbers and distribute the weight bearing evenly across the joint surface.
The meniscus is made of fibrocartilage, which gives it a rubbery texture. Within the meniscus, there are also fibers of collagen that help it to maintain their c-shape. The meniscus has blood supply only at its outer attachments. Therefore, about 4/5 of a meniscus has no blood supply and therefore cannot heal on its own.
Causes of Meniscus Tears
In a young, healthy person, the menisci are very firm with smooth edges. Damage to the menisci in younger people is rare without a specific traumatic injury. Meniscus tears in older people occur as the meniscus tends to slowly break down as people age.
Sports meniscus tears
Meniscus tears in young people can happen during sports, usually during a twisting or pivoting injury.
Meniscus tears are most common when associated with an Anterior Cruciate Ligament (ACL) tear. About half of all people with an ACL tear also have a torn meniscus. Most of these are lateral meniscus tears (on the outer side of the knee).
Wear and tear meniscus tears
As people age, wear and tear on the menisci can cause small tears. This is common in people over the age of 40. The meniscus slowly tears and can get caught with squatting activities or with sitting for long periods. When people talk about torn cartilage in the knee, they usually mean a meniscus tear.
What are The Symptoms of Meniscus Injuries?
Common symptoms of meniscus tears are:
- Pain in one spot on the inner or outer side of the knee.
- Pain when bending and squatting activities.
- Decreased range of motion (ability to bend and straighten the knee).
- Feeling like the knee is clicking or catching.
- Feeling like the knee is locking.
You can have a meniscus tear with no symptoms. Most people with meniscus tears that happened with an ACL tear have no symptoms.
How are Meniscus Injuries Treated?
Treatment for a meniscus tear depends on the type of tear, how big it is, and where it’s located. About 80% of meniscus tears will heal with proper physical therapy.
Most meniscus tears that happen along with an ACL tear don’t require surgery. In someone with an ACL tear, a torn meniscus is usually found when the orthopedic surgeon orders an MRI to confirm the ACL tear. The MRI tends to show tears of the meniscus that are not causing symptoms for the patient. Meniscus repair surgery isn’t necessary and can lead to a longer recovery from ACL reconstruction.
In older patients with meniscus tear symptoms, it is important to obtain plain x-rays of the knees to determine if the knee has any arthritic changes in the knee. When the patient has an arthritic wear of the knee joint, it is difficult to determine whether symptoms are from the arthritic changes in the knee or the meniscus tear. Most older patients with meniscus tears can obtain relief of their symptoms without surgery.
Read more about treatment for meniscus injuries.