Hip and Knee Arthroplasty - Surface Hippy Guide to Hip Resurfacing

and 79.7% for thrust plate). Over one quarter of
revision procedures are undertaken on individuals
less than 65 years of age (26.5%) (Table HG2).
There has been little change in the proportion of
younger individuals (less than 65 years) receiving
the different categories of primary hip
replacement during the last five years (Figure
HG2).
Diagnosis
The diagnosis for almost all primary partial hips is
fractured neck of femur (94.0%). Osteoarthritis
is the major reason for most primary
conventional total hip replacements (88.3%) and
total resurfacing replacements (94.0%).
The principal cause for revision of hip
replacement is aseptic loosening (45.7%). The
reason for revision of primary procedures
recorded by the Registry is different when
compared to the reason for revision of all revision
procedures. This is because early to mid term
revisions are compared to all revision procedures
recorded by the Registry, many of which have
been undertaken on procedures performed prior
to the Registry collecting data. These differences
are also dependent on the class of prostheses
used for the primary procedure.
Dislocation (31.5%) is the most common reason
for revision of known primary conventional total
hip replacements. Fractured neck of femur
(41.1%) is the most common reason for revision
of total resurfacing hip replacement.
Use of different Categories of Hip
Replacement
The most common hip procedure is a primary
total hip (70.8% of all hip replacement
procedures). Primary partial hip replacement
accounts for 16.7% and revisions 12.4% of all
hip procedures (Table HG1).
During the last five years, the proportion of
primary total hip replacement has increased from
70.1% (2003) to 72.5% (2007). The proportion
of primary partial hips has declined from 17.0%
(2003) to 16.1% (2007). Revision procedures
have also declined as a proportion of all hip
replacements from 13.0% (2003) to 11.4%
(2007). It is important to appreciate that the
change in the proportion of revision procedures is
not necessarily indicative of a reduction in the
rate of revision. It is a measure of the number of
revision procedures as a percentage of all hip
replacement procedures and therefore is affected
by the number of other types of hip replacements
undertaken.
State and Territory Variation in Use
There is variation in the number of hip
replacement by state in most categories. In
2007, South Australia had the highest percentage
of partial hip replacement (18.2%) and ACT/NT
the lowest (12.5%). In 2007 the ACT/NT had
the highest percentage of primary total hip
replacement (75.3%) and Queensland the lowest
(69.8%) (Figure HG3). The percentage of
revision procedures also varies with Queensland
having the highest percentage (12.7%) and
South Australia the lowest (9.1%) in 2007
(Figure HG3). Queensland and WA were the only
states that had an increase in the percentage of
revision procedures from 2006 to 2007 ,however
the percentage of revisions in WA remains low
compared to most other states (11.7%) for 2007
(Figure HG3).
Bilateral Primary Hip Replacement
For the purpose of this report, the definition of a
bilateral primary procedure is when an individual
has undergone hip replacement in both hips
regardless of the type of primary hip replacement
and the timing of the second primary hip
procedure. Bilateral hip replacement is not
uncommon with 12.5% of patients having
bilateral hip replacement within five years.
The Registry has recorded 16,122 individuals
having undergone bilateral primary hip
replacement. The most common type of bilateral
primary hip replacement is bilateral primary
conventional total hip (83.4% of all bilateral
procedures) followed by bilateral primary total
resurfacing hip replacement (7.9%) (Table HG3).
Same day bilateral procedures are much less
common in hip replacement compared to knee
replacement and account for 5.4% of all bilateral
hip procedures recorded by the Registry. Of
those individuals who have had bilateral primary
conventional total hip replacement, 4.6% were
undertaken on the same day. Same day bilateral
total resurfacing accounts for 18.2% of all
bilateral total resurfacings (Table HG3).
General Comparison of Outcomes
The main outcome of the Registry is the time to
first revision of a primary hip replacement. The
outcomes of procedures are measured in two
ways; using the number of revisions per 100
observed component years and using the
cumulative percent revision at specified time
points (see Appendix 1 for the full definition).
Primary conventional total hip replacement has
the lowest revision rate compared to total
resurfacing and partial hip replacement (0.8, 1.0
and 1.5 respectively) (Table HG4). This
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