KNEE REPLACEMENT TREATMENT The knee joint is the joint between the lower end of the femur (thigh bone) and the upper end of tibia (leg bone). The patella (kneecap) articulates with the femur and is an integral part of the quadriceps (extensor) mechanism. The articulating surfaces are covered by a layer of smooth and shock-absorbent tissue called hyaline cartilage. The joint is enclosed by a covering called the capsule. This is lined on its inner surface by a layer of synovium which secretes synovial fluid into the joint. This fluid lubricates the joint and provides nourishment to the hyaline cartilage. The knee derives its stability from ligaments that connect the bones (collateral and cruciate ligaments). It is controlled by the quadriceps muscle (extensor) and the hamstring muscles (flexors).