The meniscus is the most frequently injured structure inside the knee. The meniscus is composed of a type of cartilage. It is shaped like a "C", and is attached to the top of the tibia (lower leg bone) and the lining (capsule) of the knee joint.
The meniscus receives its blood supply from small arteries in the capsule. Unfortunately, only the outer portion of the meniscus receives any blood. As with all of the body's structures, blood (oxygen, nutrients) is critical for healing.
Many people ask why their meniscus tore. The most common reason is that cumulative use over a long period of time gradually weakened the meniscus to the point where the last use before the tear triggered the injury. Often the activities of daily life are responsible for the tear. Examples include tears when squatting, walking, or slightly twisting the knee. On the other end of the spectrum, substantial trauma such as falling from a height, running, or being hit can cause a tear.
Regardless of the reason, once the meniscus is torn, its ability to act as a shock absorber decreases. People will typically experience some of the following symptoms: Clicking, popping, instability (a feeling of the knee being loose or giving out), apprehension (a feeling that the knee may give out), pain, swelling, or locking (the knee gets stuck). Since the amount of pressure on the cartilage increases with the size of the tear, there is also a greater likelihood that arthritis will develop.
The meniscus can tear in a number of different patterns. Depending on the location and size of the tear the symptoms will vary. Some people experience only slight discomfort when performing certain activities and the tear has little impact on their lives. Some people have incapacitating pain and can't walk. Others experience episodes of the knee giving out. Many patients will notice that the symptoms come and go. The length of time between symptoms and the length of time those symptoms last will vary. One reason is that the torn tissue moves. A portion of this torn piece of tissue can move into the center of the knee and cause pain. Then, when it moves back the pain decreases and the knee feels better.
The meniscus does have a blood supply and it can sometimes heal on its own. When the meniscus does not heal and continues to cause symptoms arthroscopy is routinely performed. Most tears can't be repaired (stitched) because the tissue is too badly damaged or degenerated. In these situations, only the torn part of the meniscus is removed. Many patients want to know if anything is put back into the knee to take the place of the tissue that is removed. Most of the time nothing is put back into the knee. Science is yet to develop a suitable substitute. The next most common question is, "Don't I need that piece of meniscus?" The answer is that particular piece of meniscus used to have a function. However, since it is torn, it is no longer functioning as a shock absorber. It is now only causing pain, clicking, giving out, etc…Therefore, removing just the damaged piece does not cause any harm.
As stated above, most meniscus tears can't be repaired. In order to be a candidate for a meniscus repair the tissue quality has to be good and the tear has to be in the correct spot. Most of the time this is not the case. However, some patients meet the criteria and are good candidates for repair. As with many things, meniscus repairs heal better in younger patients. We are experienced in all meniscal surgery. That includes both meniscectomy (removal) and repair.
Recent research has demonstrated that one type of meniscal tear has a particularly poor prognosis without surgery. It is called a meniscal root tear. The meniscal root tear can result in a complete detachment of the meniscus. When this occurs the entire meniscus may no longer function. This particular type of tear is more likely to require repair.
Knee arthroscopy for a meniscal tear is done as an outpatient procedure. Patients go home the same day.