The meniscus is a wedge shaped structure that resembles a horseshoe in shape. We have 2 in each knee, and they face each other to act as cushions between the thigh and shin bone. The medial meniscus is located on the inside of the knee, while the lateral meniscus is located toward the outside half of the joint. They are made of a tough cartilage construct, and help nourish parts of the knee. They have an extensive blood supply, but receive nutrients from the joint fluid as well.
In athletes, most tears of the meniscus are the result of trauma. In the average layperson, however, tears are caused by compression and twisting forces together across the knee. Often, they are damaged along with injuries to the large ligaments of the knee (anterior cruciate ligament). As we get older, this meniscus cartilage tends to lose its flexibility, becomes stiffer, and tears can occur through trivial events. Tears can happen by squatting, bending, running, etc. If left untreated, these tears can worsen, and cause early degeneration of the knee. This degeneration can lead to early arthritic changes in the articular cartilage that covers the bones.
We diagnose meniscus tears usually from a good history and physical exam. The presence of sudden onset of pain at the joint line level, catching, popping, or locking of the knee are good indicators. Many patients lose the ability to bend or straighten the knee completely, because a lose tear is blocking complete motion of the joint. Often, you will see pain and swelling for no reason, and this can be attributed to a degenerative tear of the meniscus cartilage. MRI's are very useful, but they are not 100 percent accurate. This is why the history and physical exam is so important.
If a meniscus tear is suspected, then this is usually treated by an outpatient procedure called arthroscopic surgery. You probably know someone who has had their knee "scoped" as it is often called. The decision to repair the tear is based on the location of the tear, age of the patient, and pattern of the injury. Some can be sutured together to allow to heal, where others are often shaved back to a stable pattern to prevent further deterioration. As we age, the meniscus cartilage can be so fragile, that no repair can be done and simple removal of the torn section is done. This is all done as an outpatient procedure, and usually takes about 20-30 minutes to do the surgery.
Rehabilitation involves early range of motion exercises to the knee, and most people can weightbear as soon as possible. Crutches are needed usually for 2-4 days.
Meniscus tears, with the improvements of arthroscopic surgery, have allowed us to treat these injuries in a successful minimally invasive technique that will allow you to return to your normal activities very quickly.