The news reports of sensational recovery after an athletic injury have been increasingly commonplace. What was once a career-ending knee injury twenty or thirty years ago is now often treatable and may allow a full return to one’s level of sports participation. The most dramatic revolution in the treatment of athletic injuries has been the emergence of orthopedic surgeons involved in SPORTS MEDICINE; physicians dedicated to the understanding and treatment of the injuries to athletes. Development of the arthroscope, or “scope,” was the single most important technological breakthrough in the treatment of these injuries. It has enabled orthopedists to evaluate and treat many conditions with much less trauma to the injured joint.
Although one frequently reads about “cartilage tears” in the newspaper, most people have some questions regarding the anatomy of the knee and how the injuries are treated. A joint is where two bones meet to allow motion. The knee joint is essentially made of two bones, several ligaments, and two types of cartilage (see figure). The bones are the end of the femur (the thigh bone) and the top of the tibia (the leg bone). These bones roll upon each other somewhat like a hinge. The shape of the bones is very specific to allow the motion necessary to run, jump, and pivot during activities. The bones are held together by bands of tissue which resemble “ropes”. These are called the ligaments. They help control the motion between the bones. The tendons are simply the extensions of the muscles that attach to the bone to allow the muscle contractions to bend and straighten the knee.
The cartilage is the last area of the knee to be described. There are two distinct types of cartilage. One provides both the smooth surface that covers the bone and the other acts as the “shock absorber” of the knee. This is where news reports can often confuse people. The media often calls both types of tissue simply “cartilage” and goes on from there. Yet, it is important to understand the difference between the two types of cartilage since each is treated very differently. The first type of cartilage is the MENISCUS. It is two crescent or “C” shaped pads that are cupped between the bones and acts very much like a shock absorber for the knee. They are white and rubbery, and there is one on each side of the knee. The one on the inner side of the knee is called the medial meniscus and the one on the outer side of the knee is called the lateral meniscus. The meniscus is generally the part of the knee injured when there are reports that an athlete had a “torn cartilage.”
The articular cartilage
The second type of cartilage is called the articular cartilage. It is the smooth glistening surface that covers the end of the bone. It acts to lubricate the joint and allow motion to occur with almost no friction, similar to ball bearings on an axle. When this cartilage wears away, the joint is stiff and painful; resulting in arthritis. This articular cartilage is injured less frequently than the meniscus in young athletes. The treatment of an injury to articular cartilage is currently somewhat controversial; therefore, the majority of this discussion will focus on meniscus injuries.
Injuries to the meniscus generally occur from a twisting type of motion when the foot is planted on the ground or occasionally from a squatting type of motion. It may occur as a non-contact injury where a player twists the knee without any collision or entanglement with another player. There are no braces or other types of exercises that can realistically prevent the injury from occuring. Often, it is simply the fate of the circumstances. The injury generally results in pain, stiffness, and swelling which may evolve over a period of time. If this occurs, the player should be evaluated by a trainer or referred directly to a physician.
In many instances, the physician can diagnosis a meniscus tear by simple examination of the knee. The doctor locates the area of tenderness and then performs precise maneuvers to help determine the injury. X-rays are almost always necessary to ensure that there are no fractures (broken bones). X-rays can visualize the bone well, but they cannot be used to see the soft-tissues (such as the meniscus). In some cases, further tests may be needed to look closer at the exact nature of the injury. Specifically, there may be a need for a MRI (Magnetic Resonance Imaging). A MRI utilizes a large magnetic and electrical field combined with a computer to form images of the inside of the knee. The MRI is specialized to look at the soft tissues of the knee. It is important to remember that every knee injury does not require a MRI, the doctor will decide if it is necessary.
If it is determined that there is a meniscus tear, the athlete and the orthopedic surgeon need to determine the exact treatment. Although tears come in all shapes and sizes, most meniscus tears generally require surgery. Only a rare few can heal on their own. An untreated meniscus tear can roughen the articular cartilage and cause further pain and injury to the knee if an athlete continues to compete on it. This could result in arthritis.
Surgery is usually an outpatient procedure. This means the patient can go home the same day as the surgery. Orthopedic surgeons use an arthroscope to look inside the knee. The scope is a long, pencil-shaped miniature lens with fiber optic lighting that magnifies the internal view of the knee. It is only 1/4 inch wide and requires only tiny incisions to visualize and probe various parts of the knee and determine the extent of injury. The scope lens is attached to a TV camera that displays the inside of the knee on a screen for the surgeon. Tiny instruments can also be introduced into the knee to work inside the joint. The surgeon looks at the various parts of the knee and can determine if there is indeed a meniscus tear. Once this is confirmed, then the decision needs to be made regarding the types of treatment.
Tears of the meniscus are treated by either trimming away the torn tissue (called a menisectomy) or repairing the tear in hopes of it healing permanently. There are many factors that determine whether a tear can be repaired successfully. If it cannot be repaired, then the torn fragment of meniscus is trimmed away from the rest of the meniscus, leaving as much meniscus as possible. This removes the torn flap of tissue, preventing it from grinding within the knee and causing more damage. The remaining meniscus’ edges are smoothed to prevent any further tearing. Unfortunately, when the media mentions an athlete having their “cartilage repaired”, they are often incorrect and the player actually had the torn portion of the meniscus removed.
After the surgery, a rehabilitation program is designed for the patient. There is a great deal of difference between a repair and a menisectomy. A meniscus repair may require several weeks on crutches and may require several months (the rest of the season) before sports can be played in order to allow the tissue repair to heal. On the other hand, when the torn tissue is removed (menisectomy), crutches may be required for only a few days and sports may begin in several weeks after the motion and strength have been regained.
Fortunately, the vast majority of players with knee injuries can return to full sports participation. The reports of pro players returning in three to four weeks refer to knees that had the torn fragment removed(menisectomy). Sports medicine physicians continue to search for the optimum way to treat players. Despite all of this great progress, there are still some limitations of modern medicine. There is not yet any dependable “artificial meniscus” or meniscus replacement. The human body is quite complex and efforts to duplicate the amazing function of the meniscus are very difficult.