A meniscus tear refers to a tear in one of the two shock-absorbing cartilage pads in the knee. It is a common knee injury. Most injuries to the meniscus are caused by trauma involving the compression and twisting of the knee as is often seen in many sports. A meniscus tear can also when lifting something heavy, kneeling, squatting, as well as during less strenuous activities. In older individuals degenerative changes that have weakened the meniscus can cause it to tear more easily.
The knee joint is a complex hinge joint connecting the thighbone (femur), which is the longest bone in the body, to the second longest bone in the body, the shinbone (tibia). It is protected in the front by the patella (kneecap), a small flat triangular bone that also plays a role in knee extension. The knee is the largest joint in the body and acts in coordination with the pelvis, hip, upper leg, lower leg, ankle and foot to facilitate a complete range of lower body movements. It is a strong weight-bearing joint that allows the leg to flex, extend, and twist slightly from side to side.
The menisci in the knee are rubbery, C-shaped discs of cartilage that are located between the thighbone and the shinbone. There are two menisci in each knee. A lateral meniscus is situated toward the outer edge of the knee and a medial meniscus is on the inside portion. The menisci function to cushion the joint and keep the knee steady by balancing body weight and forces across the knee. In addition to providing shock-absorption and stability, the menisci allow the joint to move smoothly.
When a meniscus becomes torn or damaged its ability to cushion the joint is compromised. Traumatic meniscus tears can occur along with other knee injuries, such as anterior cruciate ligament tears.
Symptoms of a torn meniscus may include:
- A popping sensation
- Stiffness and swelling
- Inability to move knee through its full range of motion
- Feeling that the knee is catching or locking
- Feeling that the knee is giving way
Evaluating for a torn meniscus begins with a thorough history of the injury and the performance of a physical exam. During the clinical examination the doctor will check for pain and tenderness along the joint as well as move the knee through a variety of positions. Imaging tests may be ordered to assess the tear in detail, to check for associated damage, and to rule out other disorders.
Treatment depends on the type of tear, its size, as well as location. Initially the RICE formula (rest, ice, compression, and elevation) may be recommended as well as medication to reduce pain and swelling. At the appropriate time physical therapy to may also help to alleviate the symptoms, strengthen the muscles around the joint and increase knee mobility and stability. If the knee fully recovers there may be no need for further treatment. However, if there are still problems and the knee remains painful, stiff, or locked, then surgery to trim or repair the damaged meniscus tissue may be recommended.