The meniscus is a specialized structure situated between the femur (thigh bone) and tibia (shin bone) that distributes force across the knee joint. The meniscus acts as a cushion between the two bones and reduces force and stress on the cartilage of the knee joint. The meniscus has its own blood supply, but only the outer third receives ample blood supply. The middle third receives some blood supply, but it is minimal, and the inner third receives no blood supply, relying on absorption of nutrients from joint fluid. The meniscus blood supply is important as it allows a torn meniscus to heal; therefore, only tears in the outer part of the meniscus are amenable to repair. Tears occurring in the inner portion of the meniscus cannot heal and are therefore excised or trimmed out (meniscectomy). Tears occurring in the outer portion of the meniscus can heal and are therefore amenable to repair.
The meniscus can be repaired using different techniques, all of which use sutures to reattach the torn portion to the intact portion. An all-inside technique uses specialized sutures that are inserted through the torn portion into the intact healthy portion and grasp the tissue just behind the meniscus. The suture is then cinched down tightly. After surgery, intensive and dedicated physical therapy according to specified protocols is essential to obtain a good result and to allow return to full activity.
Tears occurring in the inner portion of the meniscus, or tears that are shredded cannot heal and are therefore excised. Excision of a meniscus is called a meniscectomy. A meniscectomy is performed during a knee arthroscopy. Using special cutting and shaving tools, the torn flaps of the meniscus are excised, and the remaining rim is trimmed and contoured as smooth as possible in an attempt to recreate the circular contour of the native meniscus. The majority of meniscectomies preserve much of the meniscus, but in some instances large portions of meniscus must be removed. Unfortunately, with increasing amounts of meniscus that is removed, the force placed on the cartilage of the knee joint increases, and those who undergo excision of large portions of the meniscus may be at risk of developing arthritis of the knee later in life. Thus, every attempt to preserve the meniscus is made during this surgery.