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Meniscal Injury and Treatment

By T. Kevin O'Malley M.D.  Sports Medicine Specialist,
Drs. Gross, Iwersen, Kratochvil & Klein, P.C.

T. Kevin O'Malley M.D.

When talking about the knee, one often hears of an injury to the cartilage of the knee. It is important to realize that there are two types of cartilage inside the knee, one a gliding cartilage, the other a shock absorber. Today's article will focus on the meniscus (plural menisci) or shock absorber cartilage.

The meniscus or semi-lunar cartilage in the knee is made out of cartilage similar to the cartilage in your nose or in your ear. This cartilage is durable yet flexible and provides a shock absorbing function for the knee. It does not have extensive nerve endings nor does it have an extensive blood supply throughout its body, and because of this, once injured, it provides a challenge for treatment.

The meniscus or semi-lunar cartilage is a C-shaped structure that rests on top of the tibia providing shock absorbing support between the tibia and the femur. In this role, it absorbs the forces of running, jumping and walking. It also has a secondary role in providing stability and facilitating the gliding motion of the knee. The meniscus is wide at its periphery but then tapers down at its center. The limited blood supply available to the meniscus is localized around the periphery. The extent of blood supply diminishes as one ages. Children will have very vascular menisci and more easily heal an injury, while adults have a very limited vascular supply and hence will pose greater problems in healing.

Meniscal injuries can come in various forms. The two most common are: 1) traumatic and 2) degenerative. In a traumatic injury, the damage is a result of either a direct blow or going from a squatting to a standing position or vice versa. At that time, a pop or snap can be heard which often is associated with a tear in the meniscus. Occasionally a tear can be so large as to cause the knee to lock or lose the ability of bend. This is also associated with swelling. Pain is caused by the cartilage wedging between the ends of the two bones. Occasionally a “locked” knee can become unlocked through hyperflexion or hyperextension. This is usually associated with a popping or thunking type sound.

It is important to address meniscus pathology because of the long-term sequela. Repeated episodes of locking and unlocking have been associated with significant articular cartilage damage. Articular cartilage is the second type of cartilage found in the knee. This is the cartilage that coats the ends of the bones. This is also referred to as the gliding cartilage. Damage to this cartilage is difficult to repair and hastens the onset of arthritis.

Degenerative tears are tears that have occurred over a long period of time. These are usually seen in the above 40 to 45 year old age bracket and may be symptomatic. Not all degenerative tears are symptomatic, and hence not all degenerative tears need surgical correction. A degenerative meniscus can be likened to an old shock absorber, one that is still doing something but isn’t providing as much support as it used to.

Treatment options for meniscal tears include repair, using non-absorbable sutures and the arthroscope, or removal, which involves the use of small biters and grinders that remove the meniscus and shape it in such a way that it resembles the previously un-torn meniscus. Both of these procedures are outpatient procedures requiring anesthesia whether it be general or spinal. Some knee procedures can be done under local. However, recent studies have shown that repeat surgeries are more common and less satisfying results are associated with straight local anesthesia for this procedure.

In determining which meniscus tear would require repair versus excision, one must keep in mind the blood supply as well as the orientation of the type of tear that is present. Only 1 in 10 menisci are candidates for repair. Even under ideal conditions, failure rate has been documented at 30 percent. In these patients, repeat arthroscopy and debridement or removal of the meniscus is required.

In conclusion the meniscus is a very important structure inside the knee providing cushioning in activities of daily living. Damage to the meniscus can result in surgery and possibly premature arthritis.

This Page Updated On:   07/09/2002 09:58 AM