What Is A Meniscus Tear?
A meniscus tear is a common injury to an important structure in the knee joint. If you’ve landed on this article, you might have experienced a meniscus tear or know someone who has. Read on to learn more about what a meniscus tear is and how it affects the knee joint.
What is the meniscus?
The menisci are semi-circular pieces of cartilage located at the proximal end, on the articulating surface, of the tibia (tibial plateau). Each meniscus is wedge-shaped, with a thicker area on the outside and tapers to a thinner area on the inside. The meniscus is a small but critical structure in the knee joint. We actually have two menisci, a medial and a lateral meniscus, in each knee.
Functions of the menisci
The menisci function in a few different ways to support optimal movement and the integrity of our knee joints. Remember that the knee joint, or femorotibial joint, is where the femur meets the tibia. Our knee is a complex joint. It’s considered a modified hinge joint because it does more than just hinge. Although its primary actions are flexion and extension, it can also do a certain amount of internal and external rotation when it’s in a flexed position. When we flex, extend, and rotate our knees, the femoral condyles roll over the upper surface of the tibia, called the tibial plateau. The menisci provide additional glide to make that a smooth, coordinated movement.
Other functions
The menisci also contribute to shock absorption in the knee. When we run, for example, we put force through our knee joints that is equivalent to several times our body weight. Our menisci help absorb the shock of impact and distribute that force. They are also part of the transmission system that distributes the load that we put through our knees through the kinetic chain of the leg and into the ground. The position and type of structure of the menisci make them important structures for helping to maintain the right balance between stability and mobility of the knees.
What is a meniscus tear?
When we move in a way that puts force through the meniscus more quickly than the meniscus can adapt or shift position, we can tear fibers in that cartilage structure. That commonly happens when we pivot suddenly while we’re also weight-bearing through our knee. That can happen when playing sports, such as when we plant a foot and then turn in basketball or soccer.
Even if we’re not weight-bearing, combining flexion and rotation can “twist” the meniscus, and adding even a little force or a sudden movement can tear it. The half-lotus position in yoga is one situation where this can happen. Deep flexion, as in a squat, can also put too much pressure on the meniscus, especially with the addition of sudden movement.
Symptoms of a meniscus tear
Often, when we experience a meniscus tear, there is a popping sound at the moment the tear happens, but not always. There might be some pain at the moment of the injury, but more often, soreness comes later, along with some inflammation and swelling. The area might feel stiff, or like you can’t fully flex and extend the knee. Depending on the type of meniscus tear, the knee may also get locked or stuck in position.
Types of meniscus tears
There are several different kinds of meniscus tears. The cartilage can tear either perpendicular to the tibia or horizontally, along the fiber direction. When the tear is perpendicular, it’s called a radial tear. When it’s horizontal, it’s called a horizontal tear.
A bucket handle tear is a vertical tear that occurs toward the center of the meniscus and can sometimes cause issues with knee function because a section of the inner cartilage is torn away from the outer section. The section that is pulled away can sometimes get caught up in the mechanism of the knee and disrupt function. Similarly, a flap meniscus tear is one where a piece of the meniscus tears away from the rest of the structure. It can also get caught up in the mechanism of the knee joint and cause issues. Complex meniscus tears include situations where someone experiences multiple types of tears and/or has less common tear patterns.
Why do so many people experience meniscus tears?
Sports and activities that combine knee flexion, rotation, and weight-bearing can certainly increase our chances of experiencing a meniscus tear. An imbalance in tissue tension between the medial and lateral sides of our knees, like valgus and varus patterns, can contribute to uneven loading through our knee joints. This can contribute to uneven pressure on the two menisci in each knee and make it more likely to put too much pressure on one side, especially during a sudden movement.
Tension around the hip joints can make it more likely that force will go into the knees in a problematic way when we combine flexion and rotation of the knee joint. Age-related degeneration of tissue in our knee joints can also increase the chances of tearing a meniscus.
What treatments are there for meniscus tears?
Each individual’s situation is unique to them. If you have experienced a meniscus tear, get a full assessment from an appropriate medical professional. They can help you understand your options and help you determine which option might best fit your situation. Treatments vary according to the size, location, and type of the meniscus tear, as well as by the specific activity level and types of activities the person does or wants to return to.
Small tears to the most external portion of the meniscus have the potential to heal on their own. There is some blood supply to the fibers closest to the outside, so healing is possible. Larger and/or more internal tears won’t heal on their own because there is insufficient blood supply. Many types of meniscus tears don’t need any treatment other than being cautious when moving the injured knee. In some cases, surgery is recommended, particularly when some piece of the cartilage is loose and interfering with the function of the knee joint in essential movements like walking.
Conclusion
The menisci are important structures in our knee joints that help them function optimally. They contribute to glide between the tibia and fibula, force transmission, shock absorption, stability, and mobility at the knee joints. When we experience a meniscus tear, all of those functions at the knee joint can potentially be compromised, depending on the location, type, and severity of the tear.