The hip is one of the largest joints of the human body and is routinely exposed to enormous load. Basically, it is a round (ball-andsocket) joint, which is not perfectly spherical. It consists of a bony socket (acetabulum), covered in cartilage with a ring of cartilage around the edge (the acetabular labrum), a central ligament and the femoral head. The femoral head is also covered with cartilage.
All load-bearing, moving surfaces of the joint are very smooth so that during walking or running, cartilage glides on cartilage.
This seemingly simple structure allows the hip joint a very large range of motion, practically in every direction.