Meniscus tears are one of the most common injuries seen in knees. The meniscus is a C-shaped piece of tissue made of fibrocartilage that sits within the knee. There are actually two menisci (plural of meniscus) in each knee. One is located between the femur and tibia on the inside or medial side of the knee, and one is located between the femur and tibia on the outside or lateral side of the knee. Meniscus tears can occur at any age. These tears can occur in athletes or weekend warriors, or in those who aren’t active or are elderly.
The meniscus has several functions within the knee. The fibrocartilage structure functions as a shock absorber and reduces stress across the knee joint. The wedge-shaped nature of the meniscus assists to spread out force distribution across the joint. It acts as a passive stabilizer of knee motion and limits extreme flexion and extension of the knee.
According to studies back in the 1990’s, the annual incidence of meniscus tears is 60-70 per 100,000 people. They more commonly occur in males than females. Often, they are associated with other injuries of the knee but they can occur in isolation. About 1/3 of all meniscus tears are associated with ACL injuries.
Meniscus injuries can occur acutely with twisting, direct contact, hyperflexion, or hyperextension injuries of the knee. However, you can also have meniscus tears that develop more chronically due to arthritis or other degenerative processes of the knee. This second group of meniscus tears is called degenerative.
Older individuals are more likely to have degenerative tears. As we age, the meniscus fibrocartilage weakens and wears thin. Worn tissue is more prone to injury. Sometimes, with weakened meniscus tissue, a simple twist of the knee that doesn’t seem like a big deal is enough to tear the meniscus.
If you have been unlucky enough to tear your meniscus, your symptoms will depend on whether you have torn the medial (inside meniscus) or lateral (outside meniscus). Whichever side was injured will usually be painful. You may have felt or heard a “pop” initially. Most people can still walk on their injured knee.
The most common symptoms include pain along the injured side of the knee, stiffness, pain with hyperflexion/hyperextension, swelling, catching or popping of the knee, the sensation of the knee wanting to give way or feeling unstable. You also may not have full range of motion with flexion or extension.
If you feel any of these symptoms, it is important to see your family doctor or an orthopedic surgeon so your knee can be examined. Physical examination is very helpful to doctors in trying to determine if there is a meniscus tear, but sometimes imaging is also needed. X-rays assess if there are any loose bodies or arthritic changes within the knee.
The meniscus does not show up on X-rays, so they can’t confirm tears, but they still are an important tool in assessing the knee. Often MRI’s are used to actually see the meniscus and whether there is a tear of the meniscus.
If you are found to have a meniscus tear, it is important to see an orthopedic surgeon so they can talk with you about both non-surgical and surgical treatment options. For acute injuries, RICE treatment is often initiated. This includes Rest, Ice, Compression, and Elevation. In addition, non-steroidal anti-inflammatory medications (NSAIDs) can be very effective for relieving pain and decreasing swelling. NSAIDs include ibuprofen and naproxen, in addition to several prescription medications.
Occasionally, steroid injections are also administered to decrease inflammation in a knee with a known or suspected meniscus tear. These injections can also relieve pain and inflammation. However, one should discuss these shots with an orthopedic surgeon, as the shots are not particularly healthy for the cartilage in the knee. Another newer treatment is an injection called PRP (platelet-rich plasma). For this shot, a patient has some blood removed. The growth and healing factors are then concentrated from the blood and re-injected into the knee.
If symptoms are not improving with NSAIDs, rest, and other previously mentioned treatments, your doctor may suggest surgical treatment. Usually surgery can be done through a minimally invasive approach that includes 2 or 3 small incisions, each less than 1 cm in length.
Depending on the tear pattern, the timing of surgery after the injury, and their ability to limit activity, some meniscal tears can be fixed surgically. Surgeons can also still treat tears that cannot be fixed by removing a small portion of the meniscus where the tear occurs, to bring the remaining meniscus tissue back to stable edges. This is called a partial meniscectomy. In other cases, where the tears are very large and patients are younger, meniscal transplantation can be sometimes performed using cadaver tissue. These options should be discussed with a qualified orthopedic surgeon.