The knee joint is comprised of the femur (thigh bone), patella (knee cap), and the tibia (shin bone), The hip is a ball and socket joint, made up of the femoral head (top of the femur) and the acebebulum, which is the socket in the pelvis. The ends of these bones are covered with articular cartilage. When this cartilage is worn down, the joint has developed arthritis, one of the most common causes hip and knee pain.
Read more: Total Joint Replacement Surgery