The simplest type of joint is the "hinge," as found in the elbows and the joints of the fingers and toes. Hinge joints allow movement in only one direction. The hinge joint of the knee, the body's largest joint, is unusual because it can swivel on its axis, allowing the foot to turn from side to side. Thus, the knee is constantly rolling and gliding during walking.
The knee, the largest joint in the body, is a hinge joint consisting of three parts. The lower end of the thigh bone, called the femur, rotates on the upper end of the shin bone, called the tibia, and the knee cap, or patella, which slides in a groove on the end of the femur.