Total hip replacement: Surgery in which the diseased ball and socket of the hip joint are completely removed and replaced with artificial materials. A metal ball with a stem (a prosthesis) is inserted into the femur (thigh bone) and an artificial plastic cup socket is placed in the acetabulum (a "cup-shaped" part of the pelvis.
The prosthesis may be fixed in the central core of the femur with methylmethacrylate cement. Alternatively, a "cementless" prosthesis is used which has microscopic pores that allow bony ingrowth from the normal femur into the prosthesis stem. The "cementless" hip lasts longer and is especially an option for younger patients.
The modern artificial hip was invented by the British orthopedic surgeon John Charnley. What Sir John did was to replace the uncomfortable, noisy stainless steel and screws in the then-available hip prostheses with polyethylene and dental cement. His device was first tested in 1972 and was found successful. Within a few years had been put in thousands of people with arthritis, permitting them to walk normally again.