Your hip is one of the largest weight-bearing joints in your body. When it’s working properly, it lets you walk, sit, bend, and turn without pain. To keep it moving smoothly, a complex network of bones, cartilage, muscles, ligaments, and tendons must all work in harmony. The hip is a very stable 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.