title: Friction and lubrication in cushion form bearings for artificial hip joints.
abstract: Two hip joint prostheses were designed and constructed to be elastohydrodynamically equivalent producing approximately equal initial contact areas and theoretical film thicknesses. One was made from conventional UHMWPE (ultra-high molecular weight polyethylene) and the other was a cushion component which had a low modulus layer introduced into the joint space. Friction measurements were carried out on a pendulum simulator apparatus and the two joints were compared. In addition the experimental results were compared with theoretical values of friction predicted from elastohydrodynamic lubrication theory. Values for the friction factor at peak load and peak velocity in the cushion cup (0.003-0.009) were much lower than in the UHMWPE cup (0.017-0.042). The low friction values in the cushion cup are consistent with fluid film lubrication in the contact with the thin lubricating film being preserved by microelastohydrodynamic action.
authors.affiliation: Department of Mechanical Engineering, University of Leeds.
authors.forename: D D
authors.initials: DD
authors.lastname: Auger
authors.forename: D
authors.initials: D
authors.lastname: Dowson
authors.forename: J
authors.initials: J
authors.lastname: Fisher
authors.forename: Z M
authors.initials: ZM
authors.lastname: Jin
mesh_terms: D017276:Friction; D006622:Hip Prosthesis; D008153:Lubrication; D008422:Materials Testing; D008954:Models, Biological; D011140:Polyurethanes; D011474:Prosthesis Design
chemical_list: D011140:Polyurethanes