An artificial knee has a shock casing and a hinge sheath. Plungers mounted in the shock casing bias the casing and sheath away from each other as a shock absorber mounted in the shock casing controls movement and absorbs shock of the casing and sheath as they move relative to one another. A stem secured...http://www.google.es/patents/US4619660?utm_source=gb-gplus-sharePatente US4619660 - Compressible rotational artificial joint
