Hip and Knee Arthroplasty - Surface Hippy Guide to Hip Resurfacing

PRIMARY TOTAL KNEE REPLACEMENT
This report is based on the analysis of 164,764
primary total knee replacements recorded in the
Registry up to and including 31 st December 2007.
This is an additional 29,965 primary total knee
replacements compared to the 2007 Annual
Report.
Analysis of Knee Replacement Systems
versus Individual Prosthesis Design
As explained in last year’s report the Registry is
able to present data on the different types of
knee prostheses. Different knee prostheses
however are generally available as part of a knee
system. The systems may contain many
alternative prostheses which may vary in design
depending on numerous features including the
method of fixation, stability, mobility, flexion
capacity and the materials used, amongst others.
Although possible, subdividing the prostheses
based on each different design presents
complexities and difficulties in providing a
coherent presentation of the data. The Registry
addresses this issue by providing information on
all knee systems and then subdividing by fixation.
Additionally, it provides analysis related to
different design features which different
individual knee systems have in common.
Finally, analysis of the revision rates of individual
prostheses looks at the catalogue ranges within a
system in an attempt to highlight differences
specific to a particular design within a system.
Usage
Primary total knee replacement is the most
frequently used primary knee procedure. It has
increased from 77.2% in 2003 to 82.0% of all
knee procedures in 2007. There has been an
increase in the proportion of total knee
replacements in all states since 2003 except for
Tasmania where there has been a decrease from
82.0% in 2003 to 79.4% in 2007 (Figure KG3).
This year there is a difference in the way
prostheses have been categorised to determine
the most frequently used prostheses. The major
difference has been an increase in the division of
systems into the different prosthesis types. The
most apparent impact on this table relates to the
reporting of the Genesis II. In previous years the
Genesis II included both cobalt chrome and
oxinium femoral components in the one group.
As a consequence it was reported as the most
frequently used prosthesis in last year’s report.
These two Genesis II prostheses are now
considered separately which has resulted in an
apparent difference in use compared to what was
previously reported. This change has however
been applied to the analysis of use across all
years since the Registry commenced data
collection and the use of both the cobalt chrome
and oxinium femoral components can now be
seen for each of the years reported.
In 2007 the Nexgen total knee was the most
used prosthesis and accounts for 13.5% of all
primary total knee procedures during that year.
The LCS, previously the most used prosthesis
since the Registry commenced data collection, is
used in 12.8% of procedures. The top five
prostheses account for 55.1% of all primary total
knee procedures, and the top ten prostheses
account for 82.7% of all procedures in 2007
(Table KT1 and Figure KT1).
There are 51 different knee systems recorded in
the Registry for 2007, compared to 52 in 2006.
Cemented systems have declined from 48 to 47
prostheses, hybrid systems have increased from
35 to 36 prostheses, and cementless systems
have remained unaltered at 26 systems for 2007
(Tables KT1-KT4 and Figures KT1-KT4).
Changes in use with Gender and Age
Females continue to undergo primary total knee
replacement more commonly (57.5% in 2007)
than males. There has been little change in the
proportion of males and females undergoing
primary total knee replacement in the last five
years (Table KT5).
Almost 90% of primary total knee replacements
are performed on individuals aged between 55
and 84 years (Table KT6). There has been little
change in the proportion of individuals in the
different age groups during the last five years.
In particular, there is no evidence to suggest that
there has been increased use of primary total
knee replacement in younger patients.
Fixation
Cementing of one or both the femoral and tibial
components continues to be the most common
method of fixation (76.3%). Hybrid fixation is
almost always cement fixation of the tibial
component (24.9%) and only occasionally the
femoral component (1.2%) (Table KT7).
Nationally the use of cement fixation for both the
tibial and femoral component has continued to
increase. It now accounts for 54.2% of all
primary total knee procedures. There has been
no change in the use of cementless fixation
during 2007 (23.3% of all primary total knee
procedures). Hybrid fixation continues to
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