Anyone at risk of twisting the knee also risks a torn meniscus, as tears can occur when the knee rotates while bearing weight. Athletes are especially at risk, particularly anyone participating in contact sports such as football or soccer, or activities involving pivoting such as skiing or tennis. In addition, the possibility of a meniscus injury increases with age due to accumulated wear and tear on the knee. And since much of the meniscus has no blood supply, when damage occurs the meniscus cannot undergo the body's normal healing process.

Since the medial meniscus is connected to multiple structures within the knee, it is more prone to injury than is the lateral meniscus. However, injuries can occur in either meniscus during twisting movements, direct impact to the knee joint or due to general cartilage degeneration.

The meniscus can be torn in two different ways. A traumatic tear happens suddenly, usually resulting from an atypical load being applied to the meniscus tissue. This can take place when the knee twists, or if there is a blow to the side of the knee. Traumatic tears are often associated with sporting activities, and can affect patients of all ages.

The second type of tear is referred to as a degenerate meniscal tear. As the meniscus ages it dries, and becomes less elastic. Therefore, with only minimal trauma the meniscus can tear in an older patient - many times with no memorable event or violent injury precipitating the tear.

In the case of a small tear, the meniscus stays attached to the front and back of the knee. However if the tear is large the meniscus may be left hanging by only a small piece of cartilage. How do you know if you have a meniscus tear? Symptoms will vary based on the severity of the injury.

If it is a minor tear, there will be slight pain and initial swelling that usually dissipates in two to three weeks.

A moderate tear will be more painful, with swelling increasing over two to three days. Although the knee may feel stiff, walking is still possible. There may be more pain felt during twisting or squatting movements. Symptoms may lessen over time but can easily recur with minor impacts, twisting, or overuse of the knee joint.

A severe tear has more noticeable and immediate symptoms. Pieces of the torn meniscus can "float" into the joint space, causing the knee to lock, catch, or pop. The knee may feel unstable or give out suddenly. The knee may swell and become stiff, and not be able to straighten immediately after the injury or within a few days.

Meniscus tears can therefore look very different, and can happen anywhere within either meniscus in all sorts of shapes.

There are generally four surgical options available to treat larger meniscus injuries or tears, all of which are typically done arthroscopically: