What is a Joint
A joint is the connection between two bones. It allows the limbs to bend and move which stiff bones do not permit. All activities such as walking, bending, sitting and climbing require the use of joints.
The Normal Hip Joint
The hip joint is a ball and socket type of joint.
It consists of a round ball (Femoral Head) at the upper end of the thigh bone (Femur) which fits into a cup shaped socket(Acetabulum) of the pelvis.The surfaces in contact are lined by glistening smooth articular cartilage which allows smooth painless movement and cushions weight transmission. The joint is surrounded by the capsule and ligaments which hold it together.
The Normal Knee Joint
The knee is a bicondylar hinge type of joint. The two condyles of the lower end of the thigh bone(Femur) meet the flatter upper end of the shin bone (Tibia). The bone ends are covered by glistening smooth articular cartilage which allows painles movement and weight transmission. In the front of the knee is the knee cap (Patella) the inner surface of which is also covered with cartilage.
Lying inbetween the femur and tibia are two C shaped Meniscii which act as shock absorbers. The whole knee is surrounded by a ligamentous capsule which holds the bones together. There are four important ligaments which add to stability. The Collateral ligaments on the outer sides and the Cruciate ligaments on the inside.