Development of morphological filtering method for specification and characterisation of hip replacement taper junctions

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The introduction of modular large head metal-on-metal (LHMoM) hip replacements promised lower wear rates and reduced chance of dislocation coupled with an increased range of motion compared to conventional metal-on-metal hips. However, the 2010 National Joint Registry reports a 5 year failure rate of LHMoM hips of 7.8% compared to 6.3% for hip resurfacings and comparisons of well functioning hips have shown the LHMoM have significantly increased metal ion levels compared to resurfacings. This has led to a widely held hypothesis that the modular head/neck taper junction could be a site of secondary wear debris and indeed wear has been indentified in this area on a number of retrieved bearing tapers. It is clear that the correct specification of this junction is vital to the optimum in-vivo performance of these bearings and that this could reduce the number of observed failures. This study will investigate the example of a number of newly manufactured total hip replacement femoral stems and will be the first to develop a method for specifying and measuring the underlying form of the textured surface of the critical neck taper which is characterised by a micro-thread. This was achieved through developing a filtering routine that allows for the extraction and isolation of the profile points that would contact the femoral head female taper counterface when in operation. In this study a series of measurements were taken on each component, axially along the neck taper. The measurements were performed using a Talyrond 365 roundness machine with a 5 m diamond stylus. The subsequently extracted profiles were firstly levelled using a least squares method in a post-process routine and were then processed using a newly developed morphological filtering routine to extract the envelope profile of contact points from the primary texture inherent in each profile.

LanguageEnglish
Title of host publicationProceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012
Publishereuspen
Pages125-128
Number of pages4
Volume1
ISBN (Electronic)978-095667900-0
Publication statusPublished - 1 Jan 2012
Event12th International Conference of the European Society for Precision Engineering and Nanotechnology - Stockholm, Sweden
Duration: 4 Jun 20128 Jun 2012
Conference number: 12
https://conferencealerts.com/show-event?id=93329 (Link to Conference Details)

Conference

Conference12th International Conference of the European Society for Precision Engineering and Nanotechnology
Abbreviated titleEUSPEN 2012
CountrySweden
CityStockholm
Period4/06/128/06/12
Internet address

Fingerprint

tapering
specifications
Metals
Specifications
metals
Bearings (structural)
Wear of materials
profiles
Diamond
threads
Point contacts
least squares method
stems
debris
Debris
Metal ions
Diamonds
isolation
metal ions
envelopes

Cite this

Bills, P. J., Lou, S., & Jiang, X. (2012). Development of morphological filtering method for specification and characterisation of hip replacement taper junctions. In Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012 (Vol. 1, pp. 125-128). euspen.
Bills, P. J. ; Lou, S. ; Jiang, X. / Development of morphological filtering method for specification and characterisation of hip replacement taper junctions. Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012. Vol. 1 euspen, 2012. pp. 125-128
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abstract = "The introduction of modular large head metal-on-metal (LHMoM) hip replacements promised lower wear rates and reduced chance of dislocation coupled with an increased range of motion compared to conventional metal-on-metal hips. However, the 2010 National Joint Registry reports a 5 year failure rate of LHMoM hips of 7.8{\%} compared to 6.3{\%} for hip resurfacings and comparisons of well functioning hips have shown the LHMoM have significantly increased metal ion levels compared to resurfacings. This has led to a widely held hypothesis that the modular head/neck taper junction could be a site of secondary wear debris and indeed wear has been indentified in this area on a number of retrieved bearing tapers. It is clear that the correct specification of this junction is vital to the optimum in-vivo performance of these bearings and that this could reduce the number of observed failures. This study will investigate the example of a number of newly manufactured total hip replacement femoral stems and will be the first to develop a method for specifying and measuring the underlying form of the textured surface of the critical neck taper which is characterised by a micro-thread. This was achieved through developing a filtering routine that allows for the extraction and isolation of the profile points that would contact the femoral head female taper counterface when in operation. In this study a series of measurements were taken on each component, axially along the neck taper. The measurements were performed using a Talyrond 365 roundness machine with a 5 m diamond stylus. The subsequently extracted profiles were firstly levelled using a least squares method in a post-process routine and were then processed using a newly developed morphological filtering routine to extract the envelope profile of contact points from the primary texture inherent in each profile.",
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Bills, PJ, Lou, S & Jiang, X 2012, Development of morphological filtering method for specification and characterisation of hip replacement taper junctions. in Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012. vol. 1, euspen, pp. 125-128, 12th International Conference of the European Society for Precision Engineering and Nanotechnology, Stockholm, Sweden, 4/06/12.

Development of morphological filtering method for specification and characterisation of hip replacement taper junctions. / Bills, P. J.; Lou, S.; Jiang, X.

Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012. Vol. 1 euspen, 2012. p. 125-128.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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T1 - Development of morphological filtering method for specification and characterisation of hip replacement taper junctions

AU - Bills, P. J.

AU - Lou, S.

AU - Jiang, X.

PY - 2012/1/1

Y1 - 2012/1/1

N2 - The introduction of modular large head metal-on-metal (LHMoM) hip replacements promised lower wear rates and reduced chance of dislocation coupled with an increased range of motion compared to conventional metal-on-metal hips. However, the 2010 National Joint Registry reports a 5 year failure rate of LHMoM hips of 7.8% compared to 6.3% for hip resurfacings and comparisons of well functioning hips have shown the LHMoM have significantly increased metal ion levels compared to resurfacings. This has led to a widely held hypothesis that the modular head/neck taper junction could be a site of secondary wear debris and indeed wear has been indentified in this area on a number of retrieved bearing tapers. It is clear that the correct specification of this junction is vital to the optimum in-vivo performance of these bearings and that this could reduce the number of observed failures. This study will investigate the example of a number of newly manufactured total hip replacement femoral stems and will be the first to develop a method for specifying and measuring the underlying form of the textured surface of the critical neck taper which is characterised by a micro-thread. This was achieved through developing a filtering routine that allows for the extraction and isolation of the profile points that would contact the femoral head female taper counterface when in operation. In this study a series of measurements were taken on each component, axially along the neck taper. The measurements were performed using a Talyrond 365 roundness machine with a 5 m diamond stylus. The subsequently extracted profiles were firstly levelled using a least squares method in a post-process routine and were then processed using a newly developed morphological filtering routine to extract the envelope profile of contact points from the primary texture inherent in each profile.

AB - The introduction of modular large head metal-on-metal (LHMoM) hip replacements promised lower wear rates and reduced chance of dislocation coupled with an increased range of motion compared to conventional metal-on-metal hips. However, the 2010 National Joint Registry reports a 5 year failure rate of LHMoM hips of 7.8% compared to 6.3% for hip resurfacings and comparisons of well functioning hips have shown the LHMoM have significantly increased metal ion levels compared to resurfacings. This has led to a widely held hypothesis that the modular head/neck taper junction could be a site of secondary wear debris and indeed wear has been indentified in this area on a number of retrieved bearing tapers. It is clear that the correct specification of this junction is vital to the optimum in-vivo performance of these bearings and that this could reduce the number of observed failures. This study will investigate the example of a number of newly manufactured total hip replacement femoral stems and will be the first to develop a method for specifying and measuring the underlying form of the textured surface of the critical neck taper which is characterised by a micro-thread. This was achieved through developing a filtering routine that allows for the extraction and isolation of the profile points that would contact the femoral head female taper counterface when in operation. In this study a series of measurements were taken on each component, axially along the neck taper. The measurements were performed using a Talyrond 365 roundness machine with a 5 m diamond stylus. The subsequently extracted profiles were firstly levelled using a least squares method in a post-process routine and were then processed using a newly developed morphological filtering routine to extract the envelope profile of contact points from the primary texture inherent in each profile.

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M3 - Conference contribution

VL - 1

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EP - 128

BT - Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012

PB - euspen

ER -

Bills PJ, Lou S, Jiang X. Development of morphological filtering method for specification and characterisation of hip replacement taper junctions. In Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012. Vol. 1. euspen. 2012. p. 125-128