Figure 1: Frontal View of Right Knee with Patella Tendon Removed

Medically speaking, the "cartilage" is actually known as a meniscus. The meniscus is a C-shaped piece of fibrocartilage which is located at the peripheral aspect of the joint. There are two meniscii in each knee, the medial meniscus, and the lateral meniscus. The majority of the meniscus has no blood supply. For that reason, when damaged, the meniscus is usually unable to undergo the normal healing process that occurs in most of rest of the body. In addition, with age, the meniscus begins to deteriorate, often developing degenerative tears. Typically, when the meniscus is damaged, the torn piece begins to move in an abnormal fashion inside the joint. Because the space between the bones of the joint is very small, as the abnormally mobile piece of meniscal tissue moves, it may become caught between the bones of the joint (femur and tibia). When this happens, the knee becomes painful, swollen, and difficult to move.

Usually this situation requires that the torn piece be removed. However, sometimes, the meniscus tear is along the peripheral (outer) aspect of the tissue.

Figure 2: Menisco-capsular Junction (Blue area)

In this area, the menisco-capsular junction, the most peripheral portion of the meniscus does have a blood supply. If the damage is primarily limited to the area of blood vessel ingrowth, then in some patients it is possible to arthroscopically repair the torn meniscus. This type of tear is specifically known as a peripheral menisco-capsular tear.

Figure 3: Peripheral Meniscal Blood Supply


When a physician is evaluating an injured knee, a history is taken to determine the specific problems that a patient is having with the knee. Next a physical examination of the area will be performed to determine the site of the pain, the presence or absence of physical findings that are known to be associated with a torn meniscus, and x-rays are performed to identify other abnormalities that may give similiar problems to those of a torn meniscus. In some instances, additional diagnostic tests such as an MRI may be ordered. If the history and physical findings indicate that a tear is present, arthroscopic surgery may be indicated for treatment. Although MRI scans are valuable in detecting meniscal tears, the peripheral menisco-capsular tear is the most difficult to detect. Often this pattern of tear is only detected at the time of the arthroscopic examination.

To examine the injured joint, it is necessary to insert a small fiberoptic telescope (arthroscope) into the joint. Typically, this is done with minature instruments that are inserted through incisions that are approximately 1/8 inch long. The procedure is performed as an outpatient. After examining the damaged meniscus through the arthroscope, the surgeon must then decide if the tear is repairable, or should be removed.

Prior to attempting a meniscal repair, the operating surgeon and the patient need to take into consideration a number of variables. Only by recognizing these variables and their impact on the probability of the success of the procedure, can the surgeon and patient make an honest assessment of the nature of the injury and the best procedure, removal or repair. Among the factors that must be considered by the surgeon are the patient's age, health, lifestyle, physical demands of the patients, the ability of the patient to undergo a major reconstructive procedure, the location of the tear, the type of the tear, associated intra-articular parthology, the width of the remaining uninjured tissue, the length of the tear, the presence or absence of ligamentous instability, and the patient's ability to remain on crutches and activity restrictions for a significant period of time. Because of all of the factors that must be considered, coupled with the poor blood supply of the meniscus, the majority of tears are not suitable for repair.

The age of the patient becomes significant because as the patient gets older, the likelihood of a degenerative tear increases and the probability of a repairable tear significantly decreases. Also, with increasing age, the quality of the meniscal tissue deteriorates, thereby decreasing the success rate of meniscal repairs.

Figure 4: Meniscal Repair with Sutures in Place

Although the meniscal repair is performed arthroscopically as an outpatient, the recovery is longer because the incisions are often larger then the standard incisions used for arthroscopic removal of a torn meniscus. Since healing must occur, the physical therapy must be slower and more cautious, most patients remain on crutches for several weeks, and complete healing may take several months.

Unfortunately, although it is technically possible to repair a torn meniscus, repair of the tear does not mean the healing will always occur. Your physician has no control over the body's ability to heal a tear. Therefore, if healing does not occur, the arthroscopic procedure will need to be repeated. Patients are usually on significant activity restrictions for a minimum of 3 months after surgery to allow for maturation of the healing process.



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