The knee is one of the larger hinge-type joints in the human body and the largest joint overall. Nevertheless, the knee is also relatively simple in form and function. Conjoining only the thigh, calf, and shin bones and allowing for as much as roughly 130-degrees of flexion, the knee actually relies on several dense ligaments to function and layers of cartilage for shock absorbency. Right in the middle of the joint where the tibia, fibula, femur, and patella (kneecap) meet, layers of cartilage allow the knee to operate smoothly: the meniscus.
The Anatomy and Function of the Meniscus
The structure of the knee is protected by several points of cartilage. Cartilage is a form of connective tissue with dense makeup, so the tissue is most often found around points of the body that may be susceptible to damage. In the knee, cartilage is found around the structured ends of the bones where they meet at the joint; the added layer helps thwart friction between the bones. However, a thick layer of rubbery cartilage is directly situated between the points where the femur and tibia and femur and fibula meet. The lateral meniscus and medial meniscus are the medical terms used to describe these two layers of rubbery cartilage.
The two menisci may be relatively small in comparison to other structures found at the knee joint, but the roles of these pads of cartilage are quite profound. For one, the meniscus allows the knee joint to withstand incredible loads. Consider what would happen if two bones, carrying the weight of the human body, were positioned directly on each other end to end. Eventually, the direct, blunt force of bone-on-bone would cause the bones to erode and degrade. Secondly, the meniscus distributes the shock when you run or jump. Instead of the shock of such an action reverberating through the bone, the rubbery menisci absorbs the strain. Just removing the lateral meniscus would lead to a contact pressure increase of around 200 percent.
Common Causes of Meniscus Injuries
Even though the meniscus of dense and rubbery, the area can be damaged with enough shock. Most commonly, injuries are caused by the sudden, severe impact of a sudden jolt. For example, if someone were to jump from an extreme height or suddenly make an abrupt stop while running, they could tear the meniscus. However, meniscus tears can also result from forceful twisting or rotation of the knee, lifting something extremely heavy, or kneeling for an extended period of time.
Meniscus tears are actually quite common, especially among those who participate in high-impact sports or are especially active. Further, older adults who may be prone to soft tissue degradation may also be at risk of meniscus injuries.
Signs of Meniscus Injury
Meniscus injury may show up in a number of ways, and the problem is not always easy to point out if you are not familiar with soft tissue injuries in the knee. A few signs of a torn meniscus include:
- Swelling of the knee
- Feeling a popping sensation when you move or bend your knee
- Discomfort when trying to rotate or twist your knee
- Difficulty fully extending the knee joint or feeling like the knee is “locked” in place
- Feeling like your knee is weak or uncomfortable when supporting your weight
Tips to Protecting the Meniscus After an Injury
In the event you have injured your meniscus, the doctor may recommend x-rays and arthroscopic examination to determine the location and severity of the tear. If you do have a meniscus tear, the general recommendation is simply to rest and use cold packs to help with pain and swelling. You may also need to take over-the-counter medications for the discomfort you experience.
In most cases, the injury to the meniscus will gradually get better, you will be able to move your knee more freely, and can resume your usual activities with just rest. Physical therapy may also help rebuild strength in the knee. In especially rare cases, surgery may be done to make direct repairs to the torn meniscus. However, this is usually only an option if the injury is causing ongoing problems with the function of your knee.
Internal Knee Cushions Keep Your Body Moving Freely
With built-in cushions to protect your knees, you are capable of doing some pretty amazing things without discomfort. While the meniscus may be a small part of the full makeup of the knee joint, these layers of cartilage really do take on a lot of stress. Without the menisci for protection, our abilities to move freely, run, play, bounce, and even kneel would be quite limited.