The use of primary total
resurfacing hip replacement has declined for the
fourth consecutive year. There was a 22.1%
reduction in primary total resurfacing
procedures compared to 2009. Analyses on a
variety of factors affecting outcome have been
presented. These include primary diagnosis,
gender, age, head size and type of prosthesis.
Patients having a total resurfacing for
osteoarthritis are revised less frequently than
patients with developmental dysplasia. Females
have a significantly higher rate of revision
compared to males. Males have an age related
rate of revision, which is significantly higher
for patients 65 years or older.

As reported last year, the difference in outcome
related to gender is largely due to the size of
the femoral component. There is an inverse
relationship between rate of revision and size
of the femoral head component. This year the
Registry has identified that there is also a
small gender specific increase in the rate of
revision in females independent of head size.

Ten year outcomes for individual
joint replacement prostheses are widely regarded
as an important milestone in assessing the
performance of prostheses.

Demographics

There have been 14,298 total
resurfacing procedures reported to the Registry,
an additional 991 procedures compared to the
last report.
The use of resurfacing hip replacement in
Australia continues to decline. The number of
procedures reported in 2010 was 22.1% less than
in 2009 and 48.6% less compared to the peak in
2005.
Osteoarthritis is the principal diagnosis for
total resurfacing hip replacement (94.8%),
followed by developmental dysplasia (2.6%) and
osteonecrosis (1.8%).
Most patients are male and the proportion of
males has increased from 71.2% in 2003 to 91.0%
in 2010

There continues to be a shift in
the use of primary total resurfacing hip
replacement to younger patients. The proportion
of patients under the age of 55 years has
continued to increase. There has been a
corresponding decrease in use for patients older
than 55 years (Figure HT34).

The majority of total
resurfacings use hybrid fixation (94.4% in
2010). There has been an increase in the
proportion of cementless fixation, increasing
from 2.3% in 2003 to 5.5% in 2010. The bearing
surface for resurfacing hip replacement is metal
on metal in almost all cases.

In 2010, the BHR remains the
most used resurfacing hip prosthesis. Although
its use has declined in absolute numbers in
2010, the proportion has increased. All other
resurfacing prostheses have also declined in use
with the exception of the Icon, which has
increased by a few procedures from a very small
base. (Table HT61).

 

Females have an increased rate of revision
compared to males. After three and half years,
females have over three times the rate of
revision compared to males (Tables HT69 and HT70
and Figure HT39). There is no age related
difference in the rate of revision for females
(Tables HT71 and HT72 and Figure HT40). The age
related revision rate is only associated with
males. Males over the age of 65 years have an
increased rate of revision compared to males
between the ages of 55 to 64 years (Tables HT71
and HT72 and Figure HT41).

 

Head Size

 

There is a relationship between femoral
component head size and the rate of revision.
Head sizes of 44mm or less have more than five
times the rate of revision compared to sizes
55mm or greater (Tables HT73 and HT74 and Figure
HT42). The effect of femoral component head size
is evident in both males and females. Previously
the Registry has reported that the head size
effect explained the gender difference in
outcome. This year however for the first time,
females have an increased rate of revision
independent of head size (Tables HT75, HT76 and
Figure HT43).

Revision diagnosis cumulative incidence
varies with head size. Head sizes less than 50mm
have a higher incidence of the five most common
reasons for revision (Figure HT44).

 

Prosthesis Types

 

The revision rates and yearly cumulative
percent revision of total resurfacing hip
prostheses are listed in Tables HT77 and HT78.
There are six prostheses with over 1,000
observed component years, the ASR, Adept, BHR,
Cormet, Durom and Mitch TRH. At seven years, the
BHR has the lowest cumulative percent revision
(5.0%) compared to Cormet (11.1%), Durom (9.6%)
and ASR (13.0%). The BHR is the only resurfacing
prosthesis with a cumulative percent revision at
ten years (6.3%).