title: The influence of simulator input conditions on the wear of total knee replacements: An experimental and computational study.
abstract: Advancements in knee replacement design, material and sterilisation processes have provided improved clinical results. However, surface wear of the polyethylene leading to osteolysis is still considered the longer-term risk factor. Experimental wear simulation is an established method for evaluating the wear performance of total joint replacements. The aim of this study was to investigate the influence of simulation input conditions, specifically input kinematic magnitudes, waveforms and directions of motion and position of the femoral centre of rotation, on the wear performance of a fixed-bearing total knee replacement through a combined experimental and computational approach. Studies were completed using conventional and moderately cross-linked polyethylene to determine whether the influence of these simulation input conditions varied with material. The position of the femoral centre of rotation and the input kinematics were shown to have a significant influence on the wear rates. Similar trends were shown for both the conventional and moderately cross-linked polyethylene materials, although lower wear rates were found for the moderately cross-linked polyethylene due to the higher level of cross-linking. The most important factor influencing the wear was the position of the relative contact point at the femoral component and tibial insert interface. This was dependent on the combination of input displacement magnitudes, waveforms, direction of motion and femoral centre of rotation. This study provides further evidence that in order to study variables such as design and material in total knee replacement, it is important to carefully control knee simulation conditions. This can be more effectively achieved through the use of displacement control simulation.
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Brockett
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Abdelgaied
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Tony
authors.initials: T
authors.lastname: Haythornthwaite
authors.affiliation: DePuy Synthes Joint Reconstruction, Leeds, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Hardaker
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: John
authors.initials: J
authors.lastname: Fisher
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK l.m.jennings@leeds.ac.uk.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Jennings
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D019544:Equipment Failure Analysis / Q000379:methods*; D017276:Friction; D006801:Humans; D007720:Knee Prosthesis; D008954:Models, Biological
keywords: Joint simulators; contact kinematics; knee prostheses; orthopaedic tribology; wear analysis/testing (biomechanics)