There are two menisci, “cartilages”, as they are commonly known. They are semi-circular, in shape and sit on top of the shin bone, tibia, within the knee. Their function is to improve the surface contact area of the upper leg, (femur), on the lower leg, (tibia) and help shock absorption through the knee during activity particularly during twisting and tuning or change of direction.
The lateral meniscus, is on the outside of the knee joint, and the medial meniscus is on the inside.
They can become traumatically damaged by either a twisting injury such as a football tackle or a gradual deterioration over time. Unfortunately, they have very little blood flow so do not heal well of their own accord.
The symptoms you get are deep pains in the joint, catching and locking feelings and at its worse, giving way. An injury often swells up considerably, but often after 24 hours of the injury. A more rapid swelling can mean ligament damage like Anterior Cruciate.
An early assessment for the extent of the injury is essential. Getting the right diagnosis and therefore treatment plan is the best way to get the issue better and to reduce the long term effects and wear and tear on the joint.