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Is a hollow centralizer necessary when using a polished, tapered, cemented femoral stem? : A randomized, controlled RSA study of 60 hips with 10 years of follow-up

Weber, Erik LU ; Olsson, Christer; Kesteris, Uldis LU and Flivik, Gunnar LU (2017) In Acta Orthopaedica 88(4). p.377-382
Abstract

Background and purpose — A tapered, polished and collarless stem is normally equipped with a hollow centralizer to prevent the stem from becoming end-bearing in the cement as the stem subsides. In a randomized clinical trial, we evaluated such a stem (MS-30), which was initially introduced with a solid centralizer but was later recommended to be fitted with a hollow centralizer. We hypothesized that while the stem would sink more, it would become rotationally stable and have less retroversion with a hollow centralizer than with a solid centralizer. Patients and methods — We randomized 60 patients with primary hip arthritis to receive either a hollow centralizer or a solid centralizer with the stem. The effect was evaluated over a... (More)

Background and purpose — A tapered, polished and collarless stem is normally equipped with a hollow centralizer to prevent the stem from becoming end-bearing in the cement as the stem subsides. In a randomized clinical trial, we evaluated such a stem (MS-30), which was initially introduced with a solid centralizer but was later recommended to be fitted with a hollow centralizer. We hypothesized that while the stem would sink more, it would become rotationally stable and have less retroversion with a hollow centralizer than with a solid centralizer. Patients and methods — We randomized 60 patients with primary hip arthritis to receive either a hollow centralizer or a solid centralizer with the stem. The effect was evaluated over a 10-year follow-up period with repeated RSA examinations, conventional radiographs, and clinical follow-ups using the WOMAC and SF-12 questionnaires. Results — At 10-year follow-up, the group with hollow centralizers had subsided more than the group with solid centralizers (1.99 mm (hollow) as opposed to 0.57 mm (solid); p < 0.001). However, rotation was similar at 10-year follow-up (mean retroversion 1.34° (hollow) and 1.30° (solid)). Both groups showed excellent 10-year results, with similar clinical outcome, and none of the stems were radiographically loose or had been revised. Interpretation — As expected, there was more subsidence in the group with hollow centralizers, and with similar magnitude to that reported in earlier RSA studies on conceptually similar prostheses. Interestingly, there was no difference in the rotational behavior of the prostheses. This stem type appears to have a design that, regardless of the type of centralizer and the possibility of subsidence, withstands the rotational forces it is subjected to very well. This study does not support the need for a hollow centralizer for these types of stems.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Acta Orthopaedica
volume
88
issue
4
pages
6 pages
publisher
Taylor & Francis
external identifiers
  • scopus:85017598586
  • wos:000404588400003
ISSN
1745-3674
DOI
10.1080/17453674.2017.1315553
language
English
LU publication?
yes
id
dce27900-b5fa-4daf-8ee6-83445efc73e9
date added to LUP
2017-07-26 08:16:53
date last changed
2018-01-07 12:13:05
@article{dce27900-b5fa-4daf-8ee6-83445efc73e9,
  abstract     = {<p>Background and purpose — A tapered, polished and collarless stem is normally equipped with a hollow centralizer to prevent the stem from becoming end-bearing in the cement as the stem subsides. In a randomized clinical trial, we evaluated such a stem (MS-30), which was initially introduced with a solid centralizer but was later recommended to be fitted with a hollow centralizer. We hypothesized that while the stem would sink more, it would become rotationally stable and have less retroversion with a hollow centralizer than with a solid centralizer. Patients and methods — We randomized 60 patients with primary hip arthritis to receive either a hollow centralizer or a solid centralizer with the stem. The effect was evaluated over a 10-year follow-up period with repeated RSA examinations, conventional radiographs, and clinical follow-ups using the WOMAC and SF-12 questionnaires. Results — At 10-year follow-up, the group with hollow centralizers had subsided more than the group with solid centralizers (1.99 mm (hollow) as opposed to 0.57 mm (solid); p &lt; 0.001). However, rotation was similar at 10-year follow-up (mean retroversion 1.34° (hollow) and 1.30° (solid)). Both groups showed excellent 10-year results, with similar clinical outcome, and none of the stems were radiographically loose or had been revised. Interpretation — As expected, there was more subsidence in the group with hollow centralizers, and with similar magnitude to that reported in earlier RSA studies on conceptually similar prostheses. Interestingly, there was no difference in the rotational behavior of the prostheses. This stem type appears to have a design that, regardless of the type of centralizer and the possibility of subsidence, withstands the rotational forces it is subjected to very well. This study does not support the need for a hollow centralizer for these types of stems.</p>},
  author       = {Weber, Erik and Olsson, Christer and Kesteris, Uldis and Flivik, Gunnar},
  issn         = {1745-3674},
  language     = {eng},
  month        = {07},
  number       = {4},
  pages        = {377--382},
  publisher    = {Taylor & Francis},
  series       = {Acta Orthopaedica},
  title        = {Is a hollow centralizer necessary when using a polished, tapered, cemented femoral stem? : A randomized, controlled RSA study of 60 hips with 10 years of follow-up},
  url          = {http://dx.doi.org/10.1080/17453674.2017.1315553},
  volume       = {88},
  year         = {2017},
}