Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/119083
Type: Thesis
Title: Wear of Highly Cross-Linked Polyethylene in Primary Total Hip Replacement
Author: Callary, Stuart Adam
Issue Date: 2016
School/Discipline: Adelaide Medical School
Abstract: Background: The most common causes for revision of total hip replacement (THR) are periprosthetic osteolysis and loosening, both related to wear of the acetabular component. Acetabular components utilizing highly cross-linked polyethylene (XLPE) have been shown to wear less than earlier conventional polyethylene. Reported in vivo XLPE wear rates vary due to differing radiographic measurement techniques and methods of reporting results. XLPE liners are manufactured using different amounts of cross-linking, which may influence wear, as may articulation size and patient age. Aims: The aims of this thesis were to (1) validate radiostereometric analysis (RSA) as the most accurate radiographic method to measure wear of XLPE acetabular components, (2) undertake a scoping review of RSA studies of XLPE wear, and (3) measure bedding-in and wear rate of XLPE using RSA to investigate the influence of: i) type of XLPE, ii) articulation size, and iii) patient age. Methods: The validation study used a hip phantom to compare known two-dimensional (2D) movements of the femoral head within an acetabular component to movements measured radiographically using RSA, Hip Analysis Suite (HAS), PolyWare, Ein Bild Roentgen Analyse (EBRA) and Roentgen Monographic Analysis Tool (ROMAN). The scoping review incorporated a systematic search of PubMed, Scopus and Cochrane databases to identify studies which used RSA to measure XLPE wear. Patients in six cohorts, differing in XLPE type, articulation size or patient age, underwent regular RSA examinations to calculate XLPE wear rates between one and five years. Results: RSA was significantly more accurate to measure 2D wear and had less variability in error than all other methods. Articulation size influenced accuracy of HAS and ROMAN measurements. Use of different acetabular reference segments did not influence accuracy of RSA. The scoping review identified 14 publications by other authors that in combination reported XLPE wear at 2–10 years follow-up of 10 primary THR cohorts comprising 209 hips. Mean proximal wear rate ranged from 0.00 to 0.06 mm/yr. However, differences in how wear was determined limited comparability between studies. Recommendations were made to enhance standardization of reporting wear. RSA studies undertaken as part of this thesis found that mean proximal bedding-in within the first year and the 2D and 3D wear rates between one and five years were higher in hips with a Marathon XLPE liner, which is manufactured with a lower radiation dose. Mean proximal wear rate was low for each of the six cohorts. Articulation size and age did not influence the wear rate at five years. Conclusion: The superior accuracy of RSA wear measurements allow much smaller cohorts to be used in clinical wear studies. The scoping review and RSA studies confirmed the low early wear rates of XLPE components irrespective of articulation size and patient age. One type of XLPE liner had a higher wear rate at five years compared to other XLPE liners. Longer-term wear rates and the relationship between XLPE and periprosthetic osteolysis are yet to be determined.
Advisor: Howie, Donald
Dissertation Note: Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 2017
Keywords: Total hip replacement
wear
polyethylene
radiostereometric analysis
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
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