Abstract
Polyethylene wear is a great concern in total joint replacement. It is now considered a major limiting factor to the long life of such prostheses. Cross-linking has been introduced to reduce the wear of ultra-high-molecular-weight polyethylene (UHMWPE). Computational models have been used extensively for wear prediction and optimization of artificial knee designs. However, in order to be independent and have general applicability and predictability, computational wear models should be based on inputs from independent experimentally determined wear parameters (wear factors or wear coefficients). The objective of this study was to investigate moderately cross-linked UHMWPE, using a multidirectional pin-on-plate wear test machine, under a wide range of applied nominal contact pressure (from 1 to 11 MPa) and under five different kinematic inputs, varying from a purely linear track to a maximum rotation of +/- 55 degrees. A computational model, based on a direct simulation of the multidirectional pin-on-plate wear tester, was developed to quantify the degree of cross-shear (CS) of the polyethylene pins articulating against the metallic plates. The moderately cross-linked UHMWPE showed wear factors less than half of that reported in the literature for, the conventional UHMWPE, under the same loading and kinematic inputs. In addition, under high applied nominal contact stress, the moderately crosslinked UHMWPE wear showed lower dependence on the degree of CS compared to that under low applied nominal contact stress. The calculated wear coefficients were found to be independent of the applied nominal contact stress, in contrast to the wear factors that were shown to be highly pressure dependent. This study provided independent wear data for inputs into computational models for moderately cross-linked polyethylene and supported the application of wear coefficient-based computational wear models.
Highlights
Total joint replacement has become a common surgical intervention for the degeneration of natural joints
The generation of polyethylene wear debris from replacement bearing surfaces is considered to be a major problem for long-term outcome of total joint arthroplasty.[1,2,3,4,5]
The pin-on-plate wear studies were conducted using the six-station pin-on-plate multidirectional wear test machine, Figure 1(a) (University of Leeds), to determine the wear factors and wear coefficients of a moderately cross-linked ultra-high-molecular-weight polyethylene (UHMWPE) pin articulating against cobalt– chrome alloy (CoCr) plate.[26,33]
Summary
Total joint replacement has become a common surgical intervention for the degeneration of natural joints. As these implants have been introduced to younger and more active patient groups, the demands on the joint replacement bearing have increased. To address these additional needs, new designs and materials have been introduced. The generation of polyethylene wear debris from replacement bearing surfaces is considered to be a major problem for long-term outcome of total joint arthroplasty.[1,2,3,4,5] Cross-linking has been introduced to reduce the wear of ultra-high-molecular-weight polyethylene (UHMWPE). Cross-linking may provide significant advantages over conventional UHMWPE, regarding the mechanical and wear properties.[6,7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
