The dominance of cyclic sliding in producing wear in total knee replacements.
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.
Blunn
G W
GW
Institute of Orthopaedics, University College, Stanmore, United Kingdom.
Walker
P S
PS
Joshi
A
A
Hardinge
K
K
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