Hip and Knee Arthroplasty - Surface Hippy Guide to Hip Resurfacing

eplacement, however this combination has not
been re-identified in this report.
The largest group is the “Re-identified and no
longer used” group which contains three
prostheses combinations, three acetabular
components and one femoral stem (Tables HT47-
HT49). Although the Margron stem was used in
2007 it was included in this group as the
company notified the Registry early in 2008 that
the prosthesis was no longer available.
One prosthesis combination and three individual
components (one stem and two acetabular
components) have been re-identified by the
Registry as having a higher than anticipated
revision rate and are still being used. These are
the F2L Multineck/Delta stem/acetabular
combination, Profemur Z stem and the MBA and
SPH-Blind acetabular components (Tables HT47-
HT49). Over recent years the use of each of
these prostheses has decreased considerably.
Graphs of the cumulative percent revision
comparing these ‘re-identified and still used’
prostheses to all other conventional total hip
procedures are presented in Figures HT34-HT37.
Prostheses and prostheses combinations that are
being identified for the first time include the
Corail/ASR femoral/acetabular combination,
Adapter (cemented), Anca Fit, Hayes Consensus
and Lyderic II (cemented) femoral stems and the
Bionik acetabular component (Tables HT47-HT49
and Figures HT38-43).
The stems identified for the first time this year
have exchangeable necks, as with the reidentified
Margron, Profemur Z and the F2L
Multineck stems. The Registry links a neck
exchange to the stem even if the intraosseous
component of the stem is not revised. The
Registry is able to distinguish these two different
types of stem revision.
It could be argued that revisions involving neck
exchange but not the intraosseous component of
a stem may unfairly identify that particular stem
as having a higher revision rate than a stem
which does not have the capacity to exchange
the neck. This is particularly so if neck exchange
was undertaken simply to alter neck orientation,
increase length or gain access to acetabular
components. It remains Registry policy to
attribute revision to all components rather than a
single component used in the primary procedure.
For example, in the instance of an acetabular
only revision, the revision is linked to both the
original acetabular and femoral components. The
reason for this is to take into account the
potential for adverse outcomes occurring from
the interaction of the individual components.
The Registry has and will continue to identify
single components when the analysis clearly
demonstrates the component has a higher than
anticipated rate of revision no matter what other
components it is combined with. This is true for
each of the individual stems identified.
The Registry has information on over 20 different
femoral stems that have exchangeable necks.
Many have been used in quite large numbers and
the majority of these prostheses have not been
identified as having a higher than anticipated rate
of revision. The identification of this number of
stems with the capacity for neck exchange must
raise the question as to whether this approach to
prosthesis design has the potential to increase
the risk of revision.
The Adapter femoral stem has a cemented and a
cementless version. The Registry has identified
the cemented Adapter stem as having a higher
than anticipated rate of revision (Adj HR=3.60;
95% CI (1.50, 8.66) p=0.0042). The two year
cumulative percent revision is 7.1%. The period
of follow up for this prosthesis is short with only
100 procedures recorded using this stem and
most of these were in 2007.
The Anca Fit stem has had limited use both in
terms of number and location and most
procedures using this prosthesis were undertaken
in 2007. It has however been identified as
having a higher than anticipated rate of revision
(Adj HR=3.00; 95% CI (1.43, 6.30) p=0.0037).
The Hayes Consensus femoral stem has 2.2
revisions per 100 component years (Adj HR=2.3;
95% CI (1.19, 4.38) p=0.0135). There have
been 189 prostheses implanted with nine
revisions, three for dislocation and four for
loosening. The three year cumulative revision is
4.6%.
The Lyderic II femoral stem is an infrequently
used prosthesis. It has a cemented (Lyderic II)
and a cementless (Lyderic II HAP) version. The
cemented version, Lyderic II, has been identified
as having a higher than anticipated revision rate
(Adj HR=2.99; 95% CI (1.23, 7.14) p=0.0151).
Lyderic II has 2.54 revisions per 100 observed
component years and a three year cumulative
percent revision of 8.5%.
The ASR cup is used for total resurfacing and
conventional primary total hip replacement. It
has been re-identified in this report as having a
higher than anticipated rate of revision when
used in total resurfacing procedures. This year
the Registry has also identified the ASR cup as
having a higher than anticipated rate of revision
in conventional total hip replacement when
combined with the Corail stem. The Corail/ASR
58