My doctor has advised me to have a total hip replacement. My sister had the same surgery, but only part of the joint was removed and replaced. How does the doctor decide whether to replace the whole joint or just part of the joint?

Total hip replacement (THR) involves removing the ball or head of the femur (thigh bone) and the socket it fits into. A partial joint replacement or hemiarthroplasty only replaces one side of the joint. Either the head of the femur or the socket the head fits into is replaced.

Most often, this decision is made based on the condition of the joint. If the cartilage inside the socket is in good condition, then a hemiarthroplasty is done. Arthritis, fracture, or loss of blood supply to the joint can cause damage to the surface of the joint. In these cases, a total joint replacement is usually needed.