Hip and Knee Arthroplasty - Surface Hippy Guide to Hip Resurfacing

PRIMARY PARTIAL HIP REPLACEMENT
The report for 2008 is based on analysis of
32,092 primary partial hip replacements recorded
by the Registry up to and including 31 st
December 2007. This section includes the
analysis of 16,503 unipolar monoblock, 7,404
unipolar modular and 8,177 bipolar procedures.
The eight primary partial resurfacing procedures
are not included in the following analyses.
Usage
The vast majority of all primary partial hip
prostheses are used for treating fractures of the
femoral neck (94%). The proportion of primary
partial hip replacements compared to total and
revision hip procedures has remained constant
over the last five years. In 2007 they accounted
for 16.1% of all hip procedures (Figure HG3).
There continues to be an increase in the use of
unipolar modular prostheses at the expense of
both unipolar monoblock and bipolar prostheses.
Unipolar modular prostheses now account for
23.1% of all partial hip replacements recorded in
the Registry and their use has increased by 9.5%
from last year (Figure HP1)
Unipolar modular prostheses are the most
common partial hip replacements in Western
Australia, South Australia, Tasmania and for the
first time New South Wales. Bipolar prostheses
remain the most common partial hip replacement
used in the ACT/NT (Figure HP1).
Unipolar Monoblock
There are only three different prosthesis types in
the unipolar monoblock category. These are the
Austin Moore type, Thompson type and Exeter
Trauma System (ETS) prostheses. The decline in
the use of unipolar monoblock procedures is
largely the result of the reduction in the use of
the Austin Moore type prostheses. Although this
type of prosthesis still remains the most
commonly used prosthesis in this category, in
terms of absolute numbers the use has declined
from a peak use of 1,988 in 2003 to 1,102 in
2007, a reduction of over 45% in four years.
The absolute numbers of Thompson type
prostheses have also reduced from a high of 636
in 2004 to 445 in 2007. The ETS has gradually
increased its use, 231 were implanted in 2007
which is 13% of all unipolar monoblock
procedures in 2007 (Table HP1 and Figure HP2).
Unipolar Modular
In 2007 there were 21 different types of unipolar
modular heads implanted, which was an increase
of four, compared to 2006. There were 37
different types of femoral stems used in primary
unipolar modular hip replacements. The Registry
has data on 98 head and stem combinations.
The Unitrax remains the most frequently used
unipolar head in 2007 and accounts for 29.6% of
all unipolar heads used. The Unipolar Head
(Smith & Nephew) remains the next most
common and its use has increased from 399 in
2006 to 594 in 2007. The top ten unipolar heads
account for 97.9% of all cases (Table HP2 and
Figure HP3).
The Exeter V40 remains the most frequently used
femoral stem with unipolar modular heads. The
top ten stems account for 91.7% of all stems
used in 2007 and there was no change in the
number of different stems used (Table HP3 and
Figure HP4).
Bipolar
There were 12 bipolar heads used in 2007
compared with 18 used in 2006. In 2007 the
UHR was again the most frequently used bipolar
head (48.7%) and the top ten bipolar heads
were used in 99.7% of all procedures. The
Exeter V40 stem was again the most common
stem used in combination with bipolar heads but
its use has been declining. The Registry now has
information on 175 different combinations of
bipolar head and femoral stem (Tables HP4 and
HP5 and Figures HP5 and HP6).
Six of the 2007 top ten femoral stems used in
combination with bipolar heads were also in the
top ten stems used with unipolar modular heads.
Changes in use with Gender and Age
Females continue to be more likely to undergo
partial hip replacement than males (71.4% in
2007) but there is a small increase in the use of
partial hip replacement in males increasing from
24.6% in 2003 to 28.6% in 2007 (Table HP6).
The proportion of females and males is similar for
unipolar monoblock, unipolar modular and bipolar
partial hip replacement and the small increase in
use in males is evident in all three categories
(Tables HP7, HP8 and HP9).
Most patients undergoing partial hip replacement
are 75 years or older, in 2007 this group
accounted for 83.7% of all partial hip
replacements (Table HP10). Unipolar monoblock
prostheses are used more often in older
individuals compared to unipolar modular and
bipolar prostheses. Of all patients receiving
unipolar monoblock prostheses 91.5% were aged
75 years or older and 54.1% were aged 85 years
and older.
24