The meniscus is a rubbery, C-shaped disc that cushions your knee. The menisci keep your knee steady by balancing your weight across the knee. A torn meniscus can prevent your knee from working right. The meniscus is nourished by small blood vessels, but the meniscus also has a large area in the center that has no direct blood supply (avascular). This presents a problem when there is an injury to the meniscus as the avascular areas tend not to heal. Without the essential nutrients supplied by blood vessels, healing cannot take place. Without treatment, a piece of meniscus may come loose and drift into the joint. This can cause your knee to slip, pop or lock.