The use of 3D surface analysis techniques to investigate the wear of matt surface finish femoral stems in total hip replacement

Brown, Leigh (2006) The use of 3D surface analysis techniques to investigate the wear of matt surface finish femoral stems in total hip replacement. Doctoral thesis, University of Huddersfield.

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Abstract

Total hip replacement is one of the most common surgical procedures carried out both in
the UK and Worldwide. With an increasing number of younger patients undergoing the
procedure, there is an emphasis on increasing the longevity of prostheses. The following
reports on a number of component studies which, when combined give an insight into the
mechanism of wear behind the loosening and failure of matt surface finish femoral stems.
By examining stems which have been explanted from patients, a method of wear
classification has been developed, and also 3D surface measurement techniques have
been employed to quantify wear through parametric characterisation and also volume
analysis. Initial findings suggested that the wear of matt finish femoral stems differs to
that of smoother polished femoral stems.
Studies also provide information regarding the nature of bone cement, its behaviour and
the interaction between stem and cement following insertion of the stem. It was found
that geometric change in bone cement occurred during polymerisation, and following
curing. This geometric change presented itself in the form of differential shrinkage. This
shrinkage of cement was observed initially through 3D surface topography analysis and
later confirmed with geometric measurement techniques.
The presence of voids between stem and cement give rise to the possibility of debris
creation and transportation, adding to the evidence for a difference in wear mechanism
between polished and matt surface finish femoral stems.
Some progress was made towards replication of wear in vitro which has future
possibilities for wear screening of materials and designs of future prostheses.
The overall conclusion of the study suggests that the dominant wear mechanism which
occurred between the stem and bone cement was abrasive in nature and this is likely to
explain the accelerated wear of matt stems which has been reported by clinicians and
researchers.