The Knee Cartilages
The knee cartilage (minisci) are a crucial part of the knee joint and easy to injure.
The word cartilage is misleading as this normally refers to the smooth friction-free surfaces of our joints.
The knee cartilages are properly called menisci (singular meniscus, a lens), and are C-shaped structures shaped rather like banked tracks. They are made of gristle (fibrocartilage), have flat lower surfaces and lie in a crescent shape in the knee joint.
There are two menisci in each knee, one in the inner compartment of the knee and one in the outer. They fill in some of the gap between the rounded thigh bone knuckle (femoral condyle) and the flat surface of the shin bone (tibial condyle).
The outer meniscus is more mobile as the inner meniscus is attached to the medial ligament. The blood supply penetrates 10-30% into the meniscus, and the nerves supply the outer part of each meniscus. The inner two-thirds of the menisci have no nerves.
Fibrochondrocytes (fibro=fibrous tissues, chondro=cartilage, cytes=cells) form the meniscus mainly from water, collagen and proteoglycan chemicals (which hold 50 times their weight in water).
As the knee bends and straightens, the cartilages glide very slightly forwards and backwards.
What are the cartilages for?
The function of the menisci is not entirely clear, but it is possible they could contribute to the knee in various ways:
Read further for how knee cartilages get injured.