The meniscus is a fibrocartilaginous structure in the knee that sits on top of the tibia (leg bone). Each knee has two menisci, a medial (inner) and a lateral (outer) meniscus. The meniscus functions like an adapter between the rounded femur (thigh bone)and flatter tibia. It also helps distribute the forces between the two bones over a greater area, helps capture joint fluid that provides lubrication and nutrition for the cartilage surfaces on the bones (articular cartilage), and helps stabilize the knee. A discoid meniscus is a congenital (born with) variant of the normal meniscus. Instead of being shaped like a “C,” the meniscus is more solid and disc shaped. Occasionally, it also has an abnormal, more mobile attachment to the surrounding structures. It tends to occur in the lateral (outer) meniscus. The meniscus may cause symptoms without injury or can cause symptoms when torn or injured.
Indications for Surgery
Surgery is indicated for people who have symptomatic tears of the meniscus. The presence of a discoid meniscus without symptoms does not warrant surgery. Meniscal tears can cause pain in the knee as well as mechanical symptoms including locking, catching, intermittent sharp pains, and sometimes even giving way.
Only the outer 10 to 30 percent of the meniscus has a blood supply that is required to allow tissues to heal. Because of this limited blood supply and limited ability to heal and repair itself, the meniscus tends to develop degenerative tears (from “wear and tear”) over time. The majority of meniscal tears are generally degenerative but sometimes a single injury can suddenly extend a developing tear, causing it to become symptomatic (painful). Unfortunately, because of the instability (movement) of the torn fragment of the meniscus and its limited blood supply, meniscal tears generally do not heal or regenerate themselves. Also, because of this limited blood supply and the fact that a majority of tears are degenerative in nature, most…