Understanding how your hip works
Your hip is a ball-and-socket joint: A ball (femoral head) at the top of the thighbone (femur) fits into a rounded socket or cup-like cavity (acetabulum) in your pelvis. Bands of tissues called ligaments form a capsule connecting the ball to the socket and holding the bones in place. A layer of smooth tissue called cartilage cushions the surface of the bones to help the ball rotate easily in the socket.