On the joint surface of the thighbone, there are two bony protrusions, which are referred to as condyles. The joint surface of the shinbone is referred to as the tibial plateau. When in a healthy condition, both joint surfaces are covered with a layer of joint cartilage, that acts as a kind of shock absorber. The synovial fluid acts as a lubricant and enables smooth movements of the bones and reduces friction.
The menisci sit between the thighbone and the shinbone. The two menisci, medial and lateral, are crescent-shaped and consist of fibrocartilage. They enable force to be better distributed in the knee, thus protecting the cartilage-covered joint surfaces.
The kneecap is embedded in the tendon structure which extends from the thighbone to the shinbone. When the leg is stretched and flexed, the kneecap slides up or down thus stabilising the knee joint at the front.