Hip and Knee Arthroplasty - Surface Hippy Guide to Hip Resurfacing

EXECUTIVE SUMMARY
This executive summary is intended to highlight
some of the major findings of this year’s report.
The information presented in this report has been
reviewed prior to its release by members of the
Australian Orthopaedic Association Arthroplasty
Society at a two day workshop held on 2 nd and
3 rd August 2008. The surgeons were invited to
provide feedback, comment and assist in
determining the information that should be
presented.
The major purpose of the Australian Orthopaedic
Association National Joint Replacement Registry
(AOANJRR) Annual Report is to provide the most
up to date information on the outcome of hip and
knee joint replacement surgery in Australia. The
value of the information presented in the annual
report is enhanced each year as a consequence
of longer follow up time and the increasing
number of procedures available for analysis.
The format of the report is largely unchanged
from previous years with the exception of the
analysis of data provided by State and Territory
Health Departments. This information is
presented as a supplementary report which is
available on the Registry website
www.aoa.org.au/jointregistry_pub.asp. As in
previous years comprehensive demographic
information on hip and knee replacement is also
available on the Registry website.
In November 2007, the Registry formally
commenced data collection on additional
arthroplasty procedures; these include shoulder,
elbow, wrist, ankle and spinal disc replacement.
Demographic data on these additional joint
replacements is presented in a separate report
also available on the Registry website.
The number of hip and knee replacements
undertaken each year continues to increase.
Analysis of state and territory health department
data indicates an overall increase of 2.1% in hip
and knee replacement for the period 1 st July
2006 to 30 th June 2007 (hips 2.9% and knees
1.4%) from the previous financial year. In
addition, most procedures were undertaken in
private hospitals (61%).
There continues to be a changing pattern in the
use of the different partial hip replacement
categories previously reported by the Registry.
The declining use of the Austin Moore type
prostheses and increasing use of unipolar
modular prostheses is again evident in 2007.
Although the Austin Moore type prostheses
remains the most used for arthroplasty
management of fractured neck of femur, its use
has halved in the last five years.
The Registry has previously identified that
revision rates of primary partial hip replacement
are significantly affected by the category of
prosthesis used, age at time of surgery and the
method of fixation. Updated data on these three
factors are again presented in this report. The
use of unipolar modular and bipolar procedures is
associated with fewer revision procedures and
the use of cement fixation for these prostheses
further reduces the risk of revision. Data on the
outcome of using conventional total hip
replacement for the management of fractured
neck of femur are presented for the first time in
the general hip section of this report.
The use of total resurfacing hip replacement has
declined for the second year. Presented again are
the factors affecting the outcome of total
resurfacing procedures, these include primary
diagnosis, type of prosthesis used, gender and
age. Patients having a total resurfacing for
osteoarthritis are revised less frequently than
patients with developmental dysplasia of the hip
and avascular necrosis. Females have a
significantly higher rate of revision and the risk of
revision increases with age. Males also have an
age related risk of revision which becomes
significantly higher after the age of 65 years.
This year the Registry is reporting an additional
factor that significantly affects the outcome of
resurfacing hip replacement, the size of the
femoral head component. There is an inverse
relationship between risk of revision and size of
the femoral head component. This relationship is
true for both males and females, and appears to
be the major cause for the difference in risk of
revision between gender as previously reported.
Increased revision with increasing age and the
relationship to femoral component head size
indicate that both bone volume and quality are
factors that may impact on the outcome of this
procedure. The ASR and the Durom prostheses
continue to be associated with an increased risk
of revision.
The use of primary conventional total hip is
increasing not only in terms of absolute numbers
but also as a proportion of all primary total hip
procedures. In 2007 the number of new femoral
and acetabular prostheses combinations reported
to the Registry also increased, with a further 128
new combinations recorded. For the first time
the Registry is reporting the outcome of
conventional hip replacement related to primary
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