title: The dominance of cyclic sliding in producing wear in total knee replacements.
abstract: From a literature survey, it was evident that a wide variety of kinematic conditions occur at the femoral-tibial bearing surfaces, including various degrees of rolling and sliding. A test machine was constructed to reproduce these conditions, applied to spherical-ended metal 'femoral' components acting on a flat polyethylene 'tibial' plateau. The load was cyclic at 2.2 kN for 10 million cycles with distilled water lubricant. For cyclic load only, a shiny depression was formed. With oscillating and sliding superimposed, there was severe surface and subsurface cracking resulting in high wear. When rolling motion was applied, a shiny wear track was formed with minimal cracking and wear. Such surface phenomena were observed in retrieved knee specimens, probably reflecting the kinematics associated with the knee. Low-conformity components inserted with high ligamentous laxity are susceptible to anteroposterior sliding and hence high wear. More-conforming components are less susceptible to wear because they limit sliding as well as reduce contact stresses.
authors.affiliation: Institute of Orthopaedics, University College, Stanmore, United Kingdom.
authors.forename: G W
authors.initials: GW
authors.lastname: Blunn
authors.forename: P S
authors.initials: PS
authors.lastname: Walker
authors.forename: A
authors.initials: A
authors.lastname: Joshi
authors.forename: K
authors.initials: K
authors.lastname: Hardinge
mesh_terms: D003343:Corrosion; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007720:Knee Prosthesis; D008855:Microscopy, Electron, Scanning; D009068:Movement; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical