A hip joint endoprosthesis comprises a shank, a joint ball at the upper end region of the shank, a ball socket, within which the joint ball is mounted to be rotationally movable, and a joint gap present between the joint ball and the joint socket. A liquid-filled or gas-filled rolling-contact bag is...http://www.google.ca/patents/US20040267375?utm_source=gb-gplus-sharePatent US20040267375 - Hip joint endoprosthesis
