The complex nature of these fractures can be better understood by looking at the anatomy that is involved. The pelvis is made up of several bones (ileum, ischium and pubic bones) which create a bony ring, meeting at the pubic symphysis in the front and the sacrum (a bone situated at the lower end of the spine) in the back. Together with a number of ligaments and muscles, the bones of the pelvis support the weight of the upper body and rest on the hip joints. The pelvis protects abdominal organs including the intestines and the bladder, as well as major nerves and blood vessels. Pelvic fractures may occur at any location on the bones depending on the nature of the accident and the areas of impact.
The acetabulum refers to the part of the pelvis that meets the upper end of the thigh bone (the femoral head to form the hip joint. In a healthy hip, these two bones fit together like a ball and cup, in which the ball rotates freely in the cup. Cartilage lines the bones where they meet at the joint and there is little friction between the surfaces during movement.
