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The measurement of wear in hip arthroplasties

Bergiers, Timothy Sean Thomas; (2021) The measurement of wear in hip arthroplasties. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Metal-on-metal (MOM) total hip replacement (THR) and resurfacing implants were designed to form a low friction bearing that would improve implant longevity, in response to the ever-aging population. However, the unanticipated release of cobalt chromium wear debris had a detrimental impact on periprosthetic tissue, resulting in many being revised and some designs being recalled. The aim of this thesis was to identify the surgeon, implant and patient factors that contributed to the increased wear of MOM hip arthroplasties and ultimately their failure. A developed software solution was found to provide improved accuracy during the quantification of volumetric wear from the bearing surface of retrieved hip implants, overcoming the limitations of current methods. Through its application, neither diametrical clearance nor manufacture dates were found to influence the wear performance of MOM Pinnacle hips, contrary to previous speculation. A high proportion of Pinnacle and ASR hips had a diametrical clearance below their specifications. Its detrimental impact on ASR bearing wear, further implicated its acetabular design in the increased prevalence of edge loading. The comparably high wear rates and whole blood metal ion levels of the ASR could explain their high revision rates. Nevertheless, the greater toxicity of taper junction debris was identified as the primary contributor to the disproportionately greater revision rates of the ASR XL, compared to its resurfacing form. Bearing wear was successfully located in vivo for the first time and predominantly isolated to the anterosuperior portion of the acetabular component, analogous to cartilage damage mapped in native hips. A potential relationship was also identified between component positioning and the location of this wear. These findings will help inform the management of a million patients worldwide that remain with implanted MOM hips, while influencing future design, quality control and the regulation of all orthopaedic implants.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The measurement of wear in hip arthroplasties
Event: UCL (University College London)
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/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
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci > Department of Ortho and MSK Science
URI: https://discovery.ucl.ac.uk/id/eprint/10122264
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