By Paul A. Markey, MD
One of the most common causes of knee pain is a torn cartilage, and it usually occurs without any warning or traumatic event. Each knee joint contains two cartilage pads; the medial meniscus and the lateral meniscus, which help to carry our weight. Their job is to distribute weight evenly in the knee and to help stabilize the knee. These two menisci withstand very large forces when we walk, run, jump, squat, pivot and change direction quickly. Most menisci make it through life without a problem, but it is not at all unusual for a meniscus to develop a split or tear.
A tear can happen in a normal meniscus with an unusually stressful activity of the knee, such as a combination of bending and twisting, as may occur in sports, gardening or high-spirited dancing at a wedding. More often it happens in a meniscus which has already been weakened by mild osteoarthritis, which most people get sooner or later to some degree and may or may not know they have. A meniscus weakened by osteoarthritis can tear under the ordinary forces of daily activities which do not bother a normal meniscus. No matter how a meniscus tears, the result is usually unpleasant. The knee often becomes painful and unable to move normally. The pain can be felt in the right or left, back or front of the knee, is often sharp and caused by a specific motion of the knee and sometimes wakes one from sleep when the sore knee rests against the other knee. Interestingly, the meniscus itself cannot feel any pain; the pain is felt by the synovium, which is the sensitive membrane which lines the knee joint and to which the meniscus is attached. The torn part of the meniscus tugs painfully on the synovium like a torn fingernail tugs on its nail bed. There may be popping, clunking, catching, locking or buckling of the knee, or a feeling of something shifting in and out of place in the joint. There is often swelling, which is fluid accumulation in the knee joint which forms in reaction to the tear.
An orthopaedic surgeon can diagnose the cause of knee pain, of which there are many. A history and physical examination and often X- rays and an MRI are done. If a torn meniscus is the problem, there are treatment options. A torn meniscus is not dangerous. It is all right to keep walking on the knee as tolerated. The only harm it causes is pain and aggravation. Sometimes the pain will subside by itself after a while, but the tear in the meniscus will never heal, and therefore the pain can return. Simple treatments can be tried, such as ice and an Ace bandage and over -the-counter pain relievers. A knee brace and an occasional cortisone shot may help. If the pain persists despite such measures, arthroscopy, which a small ambulatory operation, is done under local anesthesia with sedation, with two one-quarter-inch incisions. Usually the surgeon removes the small torn piece of meniscus. The patient goes home within a couple of hours, and may resume walking immediately without crutches. Other activities, including sports, may be resumed gradually as tolerated. In most cases, this operation gets rid of the pain. Occasionally the meniscus can be repaired instead of a piece being removed. In this case, the recovery is much longer, and crutches are usually needed for about six weeks. Although no operation can guarantee success, and all operations have some risk, arthroscopic meniscectomy, which is the arthroscopic removal of a torn piece of meniscus, is one of the smallest, quickest, safest, most common and most successful operations in orthopaedic surgery.