How does the hip work?
The hip is a ball and socket joint. The ball is the large, round upper end of the thighbone (femur). This fits into a cuplike socket (acetabulum) on the outer side of your pelvis, or hipbone. The bones of the hip joint are covered with a layer of cartilage, a smooth, tough tissue that keeps the bones from rubbing together. (You’ve probably seen cartilage on the end of a chicken drumstick.) Muscles and ligaments (tough bands of tissue) surround the joint and hold the ball in place inside the socket.