This 3D animation from The Human Atlas explains Hip Replacement.

The skeletal system provides the framework for the body and protects the internal organs. The hip joint supports most of the upper body weight. As a person ages the bones become thinner and more brittle, increasing the risk for injury.

The hip joints are located in the pelvis; they connect the torso to the legs and support the upper body weight. The bones of the pelvis, the pubis, the ischium, and the ilium, form a ball-and-socket joint together with the head of the femur, the long thigh bone. Injury and the wear and tear of aging can damage this joint, increasing the risk for a femoral fracture or hip fracture. A hip fracture is most likely to be repaired with hip replacement surgery.

During hip replacement surgery, the hip socket is cleaned of all cartilage and arthritic bone. A plastic cup is placed in the enlarged hip socket. Then, the top of the femur is removed and a metal ball is inserted into the top of the femur. A metal stem is also inserted into the femur to add stability to the prosthesis.

Elderly patients and patients with osteoporosis are at increased risk for hip fractures requiring hip replacement surgery.

There are several potential complications associated with this procedure that should be discussed with a doctor prior to surgery.