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An Investigation into an All Polymer Knee Joint Replacement

Adesina, Temitope Simon; (2021) An Investigation into an All Polymer Knee Joint Replacement. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

My thesis describes a series of tests aimed at investigating the suitability of polyetheretherketone (PEEK), carbon fibre reinforced polyetheretherketone (CFR-PEEK), polyethylene and acetal in an all polymer, metal free total knee replacement. Central to this study was the investigation of the wear performance of these polymers as bearing materials under two different loading conditions and in comparison, to contemporary metal on polyethylene (MoP) bearings. The concept of an all polymer total knee replacement (TKR) is intended to realise physiological stress distribution within periprosthetic bone, reduce stress shielding and bone loss and eliminate biological activity to particulate metal alloy. The hypothesis was that an all polymer bearing will generate reduced or similar amounts of wear when compared with the traditional metal-on-plastic bearing and may provide an alternate metal-free method of replacement. Following unidirectional pin on plate testing, wear of the different bearing combinations was assessed using gravimetric analysis, digital photography, surface profilometry and scanning electron microscopy (SEM). Characterization of wear particles generated from these bearing combinations was conducted following digestion of the particle containing lubricant fluid using an acid digestion method with isolated particles subjected to SEM analysis and an automated image analysis sequence. Subsequently, the inflammatory response of depyrogenated, endotoxin free wear particles retrieved from the pin-on-plate test was cultured with monocytes and cytokine production (TNF-α, IL-1β and Il-6) quantified as measured using ELISA. The key findings from my thesis were that using a pin on plate test setup designed to simulate a simplified knee couple, PEEK pins articulated against moderately cross-linked polyethylene plate exhibited comparable wear loss, a similar wear quantity, morphology and inflammatory potential to the contemporary metal on polyethylene articulations. CFR-PEEK was found unsuitable as a bearing surface in an all polymer TKR. Based on this, my hypothesis can be accepted as it may be possible to replace CoCr in TKR. However, before translation to clinical use, exhaustive appraisal of new bearing components is necessary to confer confidence in their appropriateness and safety. An all polymeric PEEK-on-a highly crosslinked polyethylene (XLPE) bearing may be a promising alternative to MoP in total knee arthroplasty.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: An Investigation into an All Polymer Knee Joint Replacement
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10120364
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